Natural Analogue Synthesis Report  

TDR-NBS-GS-000027 REV 01

May 2004

1. INTRODUCTION 
1.1 PURPOSE OF REPORT AND LIMITATIONS 
The purpose of this report is to present analogue studies and literature reviews designed to 
provide qualitative and quantitative information to test and provide added confidence in process 
models abstracted for performance assessment (PA) and model predictions pertinent to PA. This 
report provides updates to studies presented in the Yucca Mountain Site Description (CRWMS 
M&O 2000 [151945], Section 13) and new examples gleaned from the literature along with 
results of quantitative studies conducted specifically for the Yucca Mountain Project (YMP). 
The intent of the natural analogue studies was to collect corroborative evidence from analogues 
to demonstrate additional understanding of processes expected to occur during postclosure at a 
potential Yucca Mountain repository. The report focuses on key processes by providing 
observations and analyses of natural and anthropogenic (human-induced) systems to improve 
understanding and confidence in the operation of these processes under conditions similar to 
those that could occur in a nuclear waste repository. The process models include those that 
represent both engineered and natural barrier processes. A second purpose of this report is to 
document the various applications of natural analogues to geologic repository programs, 
focusing primarily on the way analogues have been used by the YMP. This report is limited to 
providing support for PA in a confirmatory manner and to providing corroborative inputs for 
process modeling activities. Section 1.7 discusses additional limitations of this report. 
Key topics for this report are analogues to emplacement-drift degradation, waste-form 
degradation, waste-package degradation, degradation of other materials proposed for the 
engineered barrier, seepage into drifts, radionuclide flow and transport in the unsaturated zone 
(UZ), analogues to coupled thermal-hydrologic-mechanical-chemical processes, saturated-zone 
(SZ) transport, impact of radionuclide release on the biosphere, and potentially disruptive events. 
Results of these studies will be used to corroborate estimates of the magnitude and limitation of 
operative processes to build realism into conceptual and numerical process models used as a 
foundation for PA in the representative case of postclosure safety. 
The current revision of this report was prepared primarily to provide results of investigations in 
2002-2003 at the Pea Blanca, Mexico natural analogue site. This material is covered in Section 
10.4. Discussions related to repository design, repository materials, and thermal loading retained 
the Site Recommendation (SR) design concepts. With these exceptions, all sections of the report 
were updated to reflect the current state of knowledge of YMP conceptual process models. 
1.2 DEFINITION OF ANALOGUE 
In the present context, natural analogues refer to either natural or anthropogenic systems in 
which processes similar to those expected to occur in a nuclear waste repository are thought to 
have occurred over long time periods (decades to millenia) and large spatial scales (up to tens of 
kilometers). Analogues provide an important temporal and spatial dimension to the 
understanding of processes not accessible to laboratory experiments that may take place in a 
nuclear waste repository and surrounding area. The use of analogy has been endorsed by the 
international nuclear waste community as a means of demonstrating confidence in the operation 

of systems, components, and processes related to nuclear waste disposal (e.g., publications of the 
International Atomic Energy Agency [IAEA] and the European Communitys Natural Analogue 
Working Group). The role of a natural analogue should  be to confirm: (a) that the process is 
in fact something which can or will occur in practice as well as in theory, and in nature as well as 
in the laboratory; (b) where, when, and under what conditions it can occur; (c) that the effects of 
the process are those envisaged in the model; and (d) that the magnitude of the effects in terms of 
scale and time are similar to those predicted for a similar set of conditions (Chapman and 
Smellie 1986 [124323], p. 167). 
1.3 ROLE OF NATURAL ANALOGUES IN PROCESS MODELS AND 
PERFORMANCE ASSESSMENT 
Natural analogues may be applied in a quantitative or a qualitative manner, depending upon the 
purpose to which they are applied and upon the specific analogue. They can provide descriptive 
information about the occurrence of various processes, or they may be able to constrain the 
bounds of those processes. Natural analogues allow testing of the pertinence of individual 
processes over geologic time and space scales, assessing the relative importance of various 
processes, and gauging the effects of process coupling. For some processes (e.g., those that are 
thermally coupled), natural analogues may be the only means of providing the degree of 
understanding of long-term and large-scale behavior needed to provide scientific confidence in 
process models for input to total system performance assessment (TSPA). Analogue 
investigations may determine the conditions under which the processes occur, the effects of the 
processes, and the magnitude and duration of the processes. 
Analogue information may also provide a body of data for testing codes and for validation of 
conceptual and numerical models. Natural analogue information may also be used to build 
confidence in databases themselves. Because natural analogues can be used to evaluate the 
validity of extrapolating from temporally limited field-scale experiments to longer time scales, or 
to add confidence when extrapolating from laboratory and intermediate-scale experiments to 
tests at larger spatial scales, they are uniquely suited to building confidence in process models. 
In this manner, they are used as a means of model validation, or confidence building. 
Less commonly, natural analogues may be used to assist and support the selection of scenarios 
and to establish the probability of occurrence of selected scenarios. Natural analogues do not 
reduce uncertainty per se; that is, the uncertainty bounds on a given parameter value may remain 
unchanged. However, natural analogues can build confidence that the bounds are set 
appropriately. Because some uncertainties are greater in natural analogues than at the site being 
characterized, information from natural analogues should only be used in conjunction with other 
information to evaluate consistency with laboratory and field data. 
Comparison of model predictions with the results of natural analogue investigations will, in 
general, only permit confirmation that the model takes into account the relevant processes in 
appropriate ways. Validation of a predictive model by such comparison provides reasonable 
assurance that the model reflects future behavior. This assurance is the level of confidence 
required by 66 FR ([156671], p. 55804), which states in 63.101(a): Demonstrating compliance 
will involve the use of complex predictive models that are supported by limited data from field 

and laboratory tests, site-specific monitoring, and natural analogue studies that may be 
supplemented by prevalent expert judgment. 
1.4 ROLE OF NATURAL ANALOGUES IN LICENSE APPLICATION 
The National Research Council endorsed the use of natural analogues as natural test cases, 
geological settings in which naturally occurring radioactive materials have been subjected to 
environmental forces for millions of years (National Research Council 1990 [100061], p. 27). 
The Councils report indicates that natural analogues are essential for validating performance 
assessment models of geologic repositories over thousands or millions of years, as well as 
forming the basis for communicating the safety of a deep geologic repository in terms the public 
can understand. The Nuclear Waste Technical Review Board concurred in these 
recommendations (NWTRB 1990 [126162], p. xiii). 
In 66 FR ([156671], p. 55804, Section 63.101(a)(2)), the Nuclear Regulatory Commission 
(NRC) has identified natural analogues as one way of demonstrating compliance with the 
reasonable expectation that postclosure performance objectives will be met. As summarized in 
Section 1.3 of this report, the NRC also specifies natural analogues as one means of supporting 
the technical basis for models in 66 FR ([156671], p. 55804). 
The content requirements for the License Application (66 FR [156671], p. 55798, Section 
63.21(c)(15)) specify natural analogue studies as one of the measures of supporting analyses and 
models that are used to assess performance of a geologic repository. In addition, the technical 
criteria for a License Application (66 FR [156671], p. 55804) specify the use of natural analogue 
information as part of the demonstration of compliance with the performance objectives of the 
disposal regulations. Further, the demonstration of the concept of multiple barriers and the 
performance of complex engineered structures must include information from natural and 
archaeological analogues (66 FR [156671], p. 55805, Section 63.102(h)). The importance of 
natural analogues in supporting performance assessment models is again included in the 
requirements for performance assessment (66 FR [156671], p. 55807, Section 63.114(g)). 
In the Yucca Mountain Review Plan, a plan stating the rules for the review and acceptance of a 
license application from the DOE, it is made clear that natural analogue evidence will be sought 
wherever the NRC staff feels analogues can provide insight. This includes insight into models, 
data ranges, and the use of features, events and processes in creating scenarios of the evolution of 
the repository system (NRC 2003 [163274]). The fact that much analogue work is being 
undertaken by the NRC underscores their stated intent in the Yucca Mountain Review Plan to use 
analogue information where they believe it to be valuable to their review function. 
Ten agreements from the DOE-NRC technical exchanges and management meetings on key 
technical issues (KTIs) include mention of analogues or information from analogue studies as 
necessary to address the agreement item. As shown in Table 1-1, two KTI agreement items are 
at least partially addressed by information in this report. A cross reference to this table is found 
in the sections of this report that could provide information related to these KTIs. 

1.5 CRITERIA FOR SELECTION OF ANALOGUES USED IN MODEL 
VALIDATION 
As pointed out by Pearcy and Murphy (1991 [157563]), the 10,000-year period required for 
high-level waste isolation is a difficult period to approximate with natural analogues. For 
instance, most ore deposits are on the order of a million to a billion years in age, whereas 
anthropogenic sites (i.e., human made) are generally on the order of a few thousand years for 
non-radioactive material analogues to a few decades for radioactive material analogues. To be 
most helpful in terms of long-term processes relevant to a high-level waste repository, it will be 
useful to find analogues with ages on the order of 1,000 to 1 million years. 
Because no single site will be a perfect analogue to all ongoing and anticipated processes at 
Yucca Mountain, focus is placed on identifying sites having analogous processes rather than total 
system analogues. Nevertheless, it is still worthwhile to attempt to match as many features and 
characteristics as possible when identifying suitable analogue sites. An ideal analogue site to 
long-term radionuclide transport at Yucca Mountain would have to satisfy the following 
conditions: (1) have a known source term, (2) have a similar set of radionuclides, (3) be well 
characterized with site data, (4) have similar geologic conditions, (5) have observable long-term 
conditions, (6) have identifiable boundaries of the system, and (7) demonstrate a clear-cut 
process that can be decoupled from other processes. It is most useful if the analogue has been in 
place for at least thousands of years, so that the results of long-term behavior are observable. 
In addition to using natural analogues for long-term predictions, models must be able to explain 
and match the transport times and pathways from contaminated sites that provide anthropogenic 
analogues, such as Hanford, Washington; the Idaho National Engineering and Environmental 
Laboratory (INEEL); and the Nevada Test Site (NTS). Anthropogenic analogue sites are a 
challenge to constrain in models, because they often contain more than one contaminated source, 
(sometimes with poorly identified source terms), have a complex mixture of radionuclides and 
other contaminants, and often occur in highly heterogeneous formations. 
With respect to choosing different geochemical transport analogues, Chapman and Smellie (1986 
[124323], p. 168) state the following: 
The essentials to bear in mind when selecting analogues are as follows: (1) The 
process involved should be clear-cut. Other processes which may have been 
involved in the geochemical system should be identifiable and amenable to 
quantitative assessment as well, so that their effects can be accountable. (2) The 
chemical analogy should be good. It is not always possible to study the behavior 
of a mineral system, chemical element or isotope identical to that whose 
behaviour requires assessing. The limitations of this should be fully understood. 
(3) The magnitude of the various physicochemical parameters involved (P, T, Eh, 
concentration, etc.) should be determinable, preferably by independent means. 
(4) The boundaries of the system should be identifiable (whether it is open or 
closed, and consequently how much material has been involved in the process 
being studied). (5) The time-scale of the process must be measurable because this 
factor is of the greatest significance for a natural analogue. 

Care must be taken in selection of an appropriate analogue to represent correctly the process of 
interest. For example, all uranium deposits are not categorically good analogues for stability of a 
nuclear waste repository. Uranium deposits indicate the long-term stability of some geologic 
environments, but some of the same ore deposits could be used to make arguments for massive 
transport of radioactive materials over large distances by natural processes. Care must also be 
exercised to exclude those analogues for which initial and/or boundary conditions are poorly 
known and where important data, such as the source term, are poorly constrained and may not be 
obtainable. A given site will usually only be analogous to some portion of a repository or to a 
subset of processes that will occur in a repository. Furthermore, additional processes will have 
occurred that are not characteristic of the repository. Therefore, choices must be made to select 
the processes of greatest relevance and the ability to isolate them for study. The long-term 
nature of analogues introduces some limitations and uncertainties, but analogues can still be used 
effectively if appropriate selection criteria are determined and applied. 
In the early 1990s, the U.S. Department of Energy (DOE)/YMP convened a panel of 
international experts in natural analogues to provide guidance in selection and use of natural 
analogues for implementation by the YMP. The Natural Analogue Review Group (NARG) 
report recommended that natural analogues be process-oriented and should address the issues 
resulting from the perturbation of a natural system (the geologic site) by the introduction of a 
technological system (the repository) (DOE 1995 [124789], p. 2). The NARG was explicit in 
stating that one should clearly discriminate such studies from those which, following the 
classical approach of earth sciences, are based on the comparative study of geological sites or 
situations. In particular, all investigations normally part of site characterization, even when 
considering comparisons with similar remote sites, such as (paleo)hydrology, etc., should not be 
considered as natural analogue studies (DOE 1995 [124789], p. 2). As reflected in the 
previously mentioned Yucca Mountain Review Plan (NRC 2003 [163274]), however, the NRC 
feels that the YMP needs to consider all potentially relevant information that could provide 
insight into the scientific merits of its modeling. This means obtaining information from all 
types of potentially analogous natural and anthropogenic analogue processes and sites. This 
broader scope of analogue work is reflected in this document. 
1.6 SCOPE AND ORGANIZATION OF REPORT 
This report considers a broad range of analogues that encompass both the engineered barriers and 
natural system components of a geological repository at Yucca Mountain. In each section, the 
conceptual basis for the process model is provided as a framework for discussion of relevant 
analogue studies and examples. Next, examples of analogue studies relevant to the operative 
processes in the conceptual models are presented. This is followed by an assessment of the 
applicability of the information or conclusions derived from the analogue. The repository design 
approach taken for the Site Recommendation (SR) (Section 2) and configuration of engineered 
barriers (Section 5) are provided as the basis against which to identify relevant analogues for 
those systems. Section 3 presents analogues related to drift stability. Section 4 provides 
qualitative corroboration of waste form degradation processes. Section 6 presents examples of 
analogues for waste package corrosion processes. Section 7 addresses analogues for engineered 
barrier components and processes. Section 8 illustrates seepage into underground openings at 
sites with varying degrees of analogy. Section 9 addresses unsaturated zone (UZ) flow processes, 
but is primarily concerned with Part I of a modeling study using INEEL data. Part I of that study 

describes a flow model that was calibrated using INEEL data and YMP modeling methods. The 
calibration parameter values were then used in Part II of the study, which is described in Section 
10 in a model of radionuclide transport at INEEL. Section 10 also includes results to date of the 
Pea Blanca field study and literature examples of analogues related to UZ transport. Section 10 
contains the main addition of new information to the report. Section 11 presents analogues 
related to coupled processes, includes an extensive literature search for geothermal analogues, 
and summarizes experimental work on drillcore from Yellowstone National Park. In addition, 
Section 11 presents the results of a field and modeling study for the Paiute Ridge coupled 
processes analogue site and a literature study of thermal-hydrologic-mechanical (THM) 
processes. Section 12 presents an analysis of uranium mill tailing data relevant to saturated zone 
(SZ) transport and includes literature examples from selected sites. Section 13 uses parameters 
measured after the Chernobyl nuclear accident to arrive at Biosphere Dose Conversion Factors 
(BDCFs) that can be compared to those applied in the Yucca Mountain Biosphere Process 
Model. Section 14 provides examples of the ways in which analogues have been used to support 
conceptual models for volcanism and seismic hazard assessments and process models. Finally, 
Section 15 discusses how the analogue information is applied, both for illustrative purposes and 
in performance assessments. The ways in which other countries have used analogues in 
performance assessment are summarized. The specific needs for analogue information requested 
by YMP performance assessment are listed, and each of the analogues covered in the report is 
mapped to its use in either conceptual model development, provision of data, or model 
validation. In a few cases, topics are identified that could potentially increase confidence with 
the use of natural analogues. 
1.7 QUALITY ASSURANCE 
This report provides corroborating information for the modeling of natural and engineered 
barrier performance at Yucca Mountain. This report was developed in accordance with AP- 
3.11Q, Technical Reports. Other applicable DOE Administrative Procedures (APs) and YMPLBNL 
Quality Implementing Procedures (QIPs) are identified in the Technical Work Plans 
(TWPs) Natural Analogue Studies for License Application (BSC 2001 [157535]) and Pea 
Blanca Natural Analogue (BSC 2002 [168402]). The Activity Evaluation in the TWP (BSC 
2001 [157535], Attachment I) graded the natural analogue work as non-Q and not subject to 
control under the DOE Office of Civilian Radioactive Waste Management (OCRWM) Quality 
Assurance Requirements and Description (QARD) (DOE 2000 [149540]). All procedures 
followed were current revisions at the time of implementation. 
The data collected under this study is corroborative and will not be used directly by Performance 
Assessment (PA) for licensing. This report will be used to support PA in a confirmatory manner 
only. The TWP stipulates that all data generated by this work will be unqualified. However, 
data that have been collected for this study have been submitted to the YMP Technical Data 
Management System (TDMS) in accordance with AP-SIII.3Q, Submittal and Incorporation of 
Data to the Technical Data Management System. The TWP also exempts the natural analogue 
work from following LP-SI.11Q-BSC, Software Management. Procedures that were followed 
during the course of the work, including AP-SIII.1Q, Scientific Notebooks, and AP-12.1Q, 
Control of Measuring and Test Equipment and Calibration Standards, are listed in the TWPs. 
Scientific notebooks are used to provide traceability to sample collection, data analysis, 
calculations, and modeling studies. 

Input for this report consisted of a combination of existing information from natural analogue 
sites reported in the literature and data collected for the YMP. Literature data not developed by 
the YMP are available for review through the Technical Information Center (TIC). Data 
collected by project personnel are available in the TDMS. Scientific notebooks (with relevant 
page numbers) used in preparation of this report are listed in Table 1-2 and are available from the 
Records Information System (RIS). Software referenced in this report is listed in Table 1-3. 
More detailed discussion of software usage is provided in relevant scientific notebooks. Finally, 
Rev 00 of this document was originally developed to meet the deliverable criteria listed in 
Section 5 of the TWP (BSC 2001 [157535]. Rev 01 was prepared primarily to provide results of 
the Pea Blanca study, as stipulated in the updated TWP (BSC 2002 [168402]). 

Table 1-1. KTI Agreements Partially Addressed in This Report 
Agreement 
Number 
Text of Agreement 
Section of 
This Report 
KIA0204 
Document that the ASHPLUME model, as used in the DOE performance 
assessment, has been compared with an analogue igneous system. (Eruptive 
AC-2). DOE agreed and will deliver calculation CAL-WIS-MD-000011 that will 
document a comparison of the ASHPLUME code results to observed data from 
the 1995 Cerro Negro eruption. This will be available to the NRC in January 2001. 
DOE will consider Cerro Negro as an analogue and document that in Eruptive 
Processes AMR (ANL-MGR-GS-000002). This will be available to the NRC in 
FY2002 (Eruptive AC-2) 
14.3 
KUZ0407 1 
Provide documentation of the results obtained from the Natural Analogues 
modeling study. The study was to apply conceptual models and numerical 
approaches developed from Yucca Mountain to natural analogue sites with 
observations of seepage into drifts, drift stability, radionuclide transport, 
geothermal effects, and preservation of artifacts. DOE will provide documentation 
of the results obtained from the Natural Analogues modeling study. The study 
was to apply conceptual models and numerical approaches developed from 
Yucca Mountain to natural analogue sites with observations of seepage into drifts, 
drift stability, radionuclide transport, geothermal effects, and preservation of 
artifacts. This will be documented in the Natural Analogues for the Unsaturated 
Zone AMR (ANL-NBS-HS-000007) expected to be available to NRC FY 2002. 
3.2, 3.3, 3.4, 
6.2, 8, 9.3, 
10.3, 10.4, 
10.5, 11.2.8- 
11.2.13, 11.3, 
11.4, 11.5 
1The Natural Analogue Synthesis Report replaces the AMR in the provision of documentation stated in KUZ 0407 

Table 1-2. Scientific Notebooks 
LBNL Scientific 
Notebook ID 
YMP M&O Scientific 
Notebook ID 
Responsible 
Individual 
Page Numbers 
Citation 
YMP-LBNL-AMS-NA-1 
SN-LBNL-SCI-108-V1 
Simmons, A. 
8387, 124 
127, 139144 
Simmons 2002 
[157544] 
YMP-LBNL-AMS-NA-2 
SN-LBNL-SCI-108-V2 
Simmons, A. 
623 
Simmons 2002 
[157578] 
YMP-LBNL-AMS-NAAU-
2 
SN-LBNL-SCI-186-V1 
Unger, A. 
5563 
Simmons 2002 
[157578] 
YMP-LBNL-DSM-ELS 
PD-2 
SN-LBNL-SCI-190-V2 
Dobson, P. 
7980 
Simmons 2002 
[157578] 
YMP-LBNL-AMS-NA 
PD-1B 
SN-LBNL-SCI-185-V1 
Dobson, P. 
7-1 
Simmons 2002 
[157578] 
YMP-LBNL-AMS-NA 
PD-photos 
SN-LBNL-SCI-185-V1 
Dobson, P. 
Roll 17, Images 
2 and 4 
Simmons 2002 
[157578] 
YMP-LBNL-AMS-NA 
PD-1 
SN-LBNL-SCI-185-V1 
Dobson, P. 
90-130 
Simmons 2004 
[169270] 
YMP-LBNL-PD-2 
SN-LBNL-SCI-241-V1 
Dobson, P. 
7-23 
Simmons 2004 
[169270] 
N/A 
SN-LANL-SCI-237-V1 
Murrell, M. 
16 
Simmons 2002 
[157578] 
N/A 
SN-LANL-SCI-237-V1 
Murrell, M. 
6, 7, 10, 12-13, 
22-27, 32-55 
Simmons 2004 
[169270] 
N/A 
SN-LANL-SCI-215-V1 
Lichtner, P. 
632, 5659, 
63, 6976, 89 
94, 100104, 
107, 110112, 
117118, 128, 
130131 
Simmons 2002 
[157578] 
N/A 
SN-LANL-SCI-234-V1 
Lichtner, P. 
16, 20, 2224, 
2633, 6168, 
7576, 83, 88 
90 
Simmons 2002 
[157578] 

Table 1-3. Software Codes Referenced in Text 
Software Name 
Version Number 
Software Tracking 
Number 
Software Referenced 
by Section 
ASHPLUME 
V 1.4LV 
10022-1.4LV-00 
14.3 
ASHPLUME 
V 2.0 
10022-2.0-00 
14.3 
CXTFIT 
V 2.1 
N/A 2 
10.3.2.1, 11.4.7.1 
DRKBA 
V 3.3 
10071-3.3-00 
14.4 
EQ3/6 
V 7.2b 
UCRL-MA-110662 
11.2.12.1, 11.3.5 
FEHM 
2.0 
10031-2.00-00 
10.3.1, 10.3.6.1, 
10.3.6.3, 10.3.6.5 
FLOTRAN 
1.0 
N/A 
10.3.1, 10.3.6.1, 
10.3.6.3, 10.3.6.4, 
11.4.7, 11.4.7.1, 
11.4.7.2, 
iTOUGH21 
V 4.0 
N/A 
9.3.3, 9.3.5, 9.3.6, 9.3.7, 
9.5 
Mathematica 
V 4.1 
N/A 
10.3.6.4 
TOUGH2 
V 1.4 
10007-1.4-01 
11.3.5 
TOUGHREACT 
V 2.2 
10154-2.2-00 
11.3.5 
TOUGHREACT 
V 2.3 
10396-2.3-00 
11.3.5 
UDEC 
V 2.0 
B00000000-01717- 
1200-30004 
14.4 
NOTE: 1 iTOUGH2 with EOS9 and EOS7r modules 
2 N/A signifies that the code is unqualified and it is currently not tracked by the Software 
Configuration Management System. 

2. REPOSITORY DESIGN SELECTION FOR SITE RECOMMENDATION 
AND RELATION TO APPLICABLE ANALOGUES 
2.1 INTRODUCTION 
Studies of natural and anthropogenic systems can improve understanding and confidence in the 
variables affecting the evaluation and operation of a selected repository design. The selection of 
appropriate analogues to build confidence in repository design parameters should focus on the 
variables affecting operational parameters rather than on a specific design for a Yucca Mountain 
repository. The Site Recommendation (SR) design approach was flexible in that a wide range of 
thermal operating modes was examined. The flexible design approach is presented in Section 
2.2. The range of potential thermal operating modes is described on the basis of three evaluated 
scenarios in Section 2.3, while Section 2.4 presents design methods by which the thermal goals 
can be achieved. Section 2.5 provides a basis for evaluating analogues to repository materials 
and processes that are discussed in subsequent chapters. This section may be updated after the 
final thermal-operating-mode decisions have been made for the repository. 
2.2 FLEXIBLITY IN DESIGN 
Refining the design and operating mode of the geologic repository at Yucca Mountain has been 
an ongoing process since inception of the YMP. This iterative design process has been focused 
on improving the understanding of how design features contribute to the performance of a 
potential repository and to the uncertainty in that performance. 
A primary design aspect has been the thermal load that will be generated by the repository. 
Previous design concepts have considered higher-temperature operating modes, in which the 
rock surrounding emplacement drifts exceeds the boiling point of water. More recently, to 
maintain flexibility in design, the design process has evolved to examine the effects on the 
repository over a wider range of thermal conditions. A flexible approach to design was 
introduced in the Yucca Mountain Science and Engineering Report (S&ER) (DOE 2001 
[153849], Section 2.1.3). The design has flexible operating modes that can be adapted to 
accommodate a waste stream with potentially evolving thermal characteristics. 
2.3 OBJECTIVES OF THERMAL OPERATING MODES 
The SR design concepts ranged from a lower-temperature operating mode to a highertemperature 
operating mode. For the lower-temperature mode, the objective is to keep the waste 
package surface temperature below 85C (DOE 2001 [153849], Section 2.1.2.3). In the highertemperature 
mode, the wall rock of the drift is above boiling temperature but the temperature is 
controlled to prevent boiling fronts from coalescing in the rock pillars between the emplacement 
drifts. Strategies that have been considered with regard to selecting the operating mode of the 
repository are presented below. 
2.3.1 Manage Boiling Fronts within the Rock Pillars 
The higher end of the thermal operating mode, presented in the Supplemental Science and 
Performance Analyses (SSPA) (BSC 2001 [155950], Table 2-1), assumes an average waste 

package maximum temperature of ~160C. This mode preserves the capability of the rock mass 
to drain percolation flux through the repository horizon by preventing the boiling fronts from 
coalescing in the rock pillars between the emplacement drifts. In this mode, the close spacing of 
waste packages with thermally blended spent fuel inventories achieves a relatively uniform 
distribution of rock temperatures along the drift, limiting potentially complex 
thermal-mechanical effects resulting from a varying thermal gradient along the drift axis. This 
operating mode would also meet a design requirement established to maintain the integrity of the 
waste package cladding by not exceeding a temperature of 350C, the temperature at which the 
cladding loses its integrity. 
2.3.2 Maintain Drift-Wall Temperatures Below Boiling 
One lower-temperature objective is to keep all the rock in the repository below the boiling point 
of water to reduce uncertainties associated with coupled thermal-hydrologic-chemicalmechanical 
processes driven by the boiling of water (BSC 2001 [155950], Section 2.3.2). In the 
higher-temperature operating mode described in the S&ER, the rock temperatures within the first 
several meters outside the emplacement drifts exceed the boiling point of water for about a 
thousand years. 
2.3.3 Reduce Uncertainty in Corrosion Rates 
The lower-temperature end of the range of thermal operating modes was defined by considering 
the potential for reducing uncertainty in the rate of localized corrosion of Alloy 22 waste 
package material. At temperatures below about 85C or relative humidity (RH) below 50 
percent, the susceptibility of Alloy 22 to crevice corrosion is very low (DOE 2001 [153849], 
Section 2.1.5, Figure 2-a). Operating the repository so that the temperature or relative humidity 
is below this window of crevice corrosion susceptibility may increase confidence that corrosion 
will not significantly reduce waste package service life. 
2.4 MANAGING THERMAL OPERATING MODES 
The temperature and relative humidity under which a repository would be operated for any 
specified underground layout can be managed either singularly or through various combinations 
of several operational parameters (DOE 2001 [153849], Section 2.1.4) such as by: 
Varying the thermal load resulting from the repository by managing the thermal output 
of the waste packages 
Managing drift ventilation prior to repository closure 
Varying the distance between waste packages in emplacement drifts. 
Figure 2-1 illustrates the variables affecting the thermal performance of the repository, from 
waste forms to emplacement drifts. 

2.5 APPLICATION TO NATURAL ANALOGUES 
Because of the flexible design approach, analogues must be considered in terms of repository 
design variables rather than attempting to match a specific design. The important variables are 
temperature of drift walls, presence or absence of a boiling front, dimensions and spacing of 
drifts, absence of backfill, and ventilation. These variables affect drift stability (addressed in 
Section 3), waste package and drip shield corrosion (discussed in Sections 5 and 6, respectively), 
processes operative within the engineered barrier system (addressed in Section 7), and thermally 
coupled processes affecting the host rock at the drift and mountain scales (covered in 
Section 11). 

Source: DOE 2001 [153849], Figure 2-8. 
Figure 2-1. Variables Affecting the Thermal Performance of the Repository 

3. REPOSITORY DRIFT STABILITY ANALOGUES 
3.1 INTRODUCTION 
Section 2 provided background information on the current flexible design for a potential 
repository at Yucca Mountain against which to discuss analogues for drift stability. The 
proposed emplacement drift diameter is 5.5 m (18 ft) (DOE 2001 [153849], Section 2.3.1.1). 
The ability of underground openings to remain open and stable depends on a number of 
variables, including: (1) rock strength; (2) the size, shape, and orientation of the opening; (3) 
orientation, length, and frequency of fracturing; (4) effectiveness of ground support, and (5) 
loading conditions. There are no exact analogues to the openings that would be created for a 
potential repository at Yucca Mountain, but numerous examples demonstrate that both natural 
and man-made underground openings can exist for thousands of years in a wide variety of 
geologic settings, even with minimal or no engineering. Analogue information is available for 
natural underground openings (Section 3.2) and man-made excavations (Section 3.3). An 
analogue demonstrating thermal effects on underground openings is presented in Section 3.4. 
Effects of ground shaking on underground openings are mentioned in Section 3.4 and discussed 
in more detail in Section 14. Information found in Section 3.2, 3.3, and 3.4 may help to support 
arguments associated with Key Technical Issue (KTI) KUZ0407 listed in Table 1-1. 
3.2 NATURAL UNDERGROUND OPENINGS 
Caves represent examples of natural underground openings. They are abundant, and in many 
cases, it can be demonstrated that they have remained open for very long spans of time. The 
oldest documented examples noted in this study are from the limestone formations of the 
Guadalupe Mountains in New Mexico. Undisturbed, uncovered alunite (a mineral that forms on 
the floor of caves) collected from cave floors has been dated at 4.03.9 million years (m.y.) for 
the Big Room at Carlsbad Caverns and at 6.0 to 5.7 m.y. for the upper level of the nearby 
Lechuguilla Cave. Alunite from other nearby caves in the Guadalupe Mountains yields ages as 
old as 11.3 m.y. (Polyak et al. 1998 [156159], p. 1919). Sections of the cave floors have blocks 
that appear to have fallen from the ceiling; however, none of the dated caves has been closed by 
rockfall, demonstrating the stability of most of these openings over millions of years. Because 
these settings are common, they demonstrate stability for most of the openings for millions of 
years. Many of these openings are as large or larger than those proposed for Yucca Mountain 
(Figure 3-1). 
The San Antonio Mountain Cave in northern New Mexico is an example of a different geologic 
setting in which an opening has remained open over a long period of time. This cave is a lava 
tube in basalt from 3.43.9 million years ago (Ma) (Rogers et al. 2000 [154320], pp. 8993). 
The cave is more than 170 m long and generally several meters wide. In some places, the ceiling 
is over 12 m high. The large size of the openings combined with abundant cooling fractures has 
resulted in fallen blocks (generally less than  m in length and width) that cover about 30% of 
the caves floor. Several spots preserve a long record (up to 1 m.y.) of sedimentation, more than 
400 cm thick, with no collapse (Rogers et al. 2000 [154320], Figure 5). Davis (1990 [144461], 
p. 338) notes that similar cave sediments in Europe date back 1.5 Ma, which suggests that longterm 
stability of caves is a common feature. 

Most lava tubes are a few thousand to a few hundred thousand years in age. They are commonly 
ellipsoidal to circular in cross section and are several meters in diameter. Some of the most 
extensive lava tubes are in the Undara region of Australia, where 190,000-year-old tubes reach 
100 km in length (Undara Experience 2001 [157515]). Figure 3-2a shows the interior of a lava 
tube in the Undara region (with a person included in the photo for scale). Lava tubes are also 
common in Hawaii (Figure 3-2b), Idaho, northern Arizona, and in the Cascade Range of 
California, Oregon, and Washington, in lava that is modern to a few thousand years in age. Most 
lava tubes exhibit partial collapse in areas where the roof is thin, but large sections of open 
tunnel persist for long periods of time. 
The maximum length of time that caves have stood open is usually not known, but the age dates 
of datable biologic or archeologic materials found in many caves indicate that the caves have 
remained open for extended periods of habitation without collapse. Some packrat middens found 
in caves are thousands to tens of thousands of years old, and Davis (1990 [144461], p. 341) 
reports that over 1,000 middens have been studied in caverns and rock shelters of the western 
United States. Stuckless (2000 [151957], p. 4-6) reports on several caves in limestone that 
contain paintings that have been dated at 11,000 to 32,000 years old. 
Kebara Cave in Mt. Carmel, Israel, is a very large opening (26 m long and 20 m wide, with a 
ceiling up to 18 m high), and sediments accumulated on the floor of the cave yield ages as old as 
50,000 years (Bar-Yosef et al. 1996 [157419], p. 305). Although the main portion of the cave 
shows no sign of collapse, a terrace in front of the cave entrance was formed by collapse 
sometime after 30,000 years ago (Bar-Yosef et al. 1996 [157419], p. 298). However, even this 
collapsed section must have stood open for more than 20,000 years, because this section was the 
entrance from before 50,000 until 30,000 years ago. 
3.3 ANTHROPOGENIC OPENINGS 
Anthropogenic, or man-made, underground openings do not provide as long a history as the 
natural ones, but they may provide a closer analogy to a mined geologic repository. Here too, 
there are abundant examples that exhibit considerable stability for hundreds to thousands of 
years, even with minimal engineering. The oldest examples are the Neolithic flint mines of 
northern Europe and England. These were mined into chalk deposits in 3,000 to 4,000 B.C. At 
one site in England, shafts that are 6 to 14 m deep access galleries that are 4 to 24 m in length 
and are still open today (Crawford 1979 [157420], pp. 832). 
Around 1,500 B.C., Egyptians began excavating tombs on the west bank of the Nile River, 
across from Luxor. Over 100 tombs were excavated in bedded and jointed limestone (Figure 3- 
3). The tombs were generally a few meters in length and width and about 2 m in height. Many 
have pillars that were left for support in the larger rooms. Most of the tombs have incurred some 
water damage to plaster and paintings on the walls and ceilings, but none seems to have suffered 
collapse (Simmons 2002 [157578], SN-LBNL-SCI-108-V2, p. 7). 
Mining of metallic ores has produced subterranean openings in a variety of rock types and often 
in intensely altered or fractured rock. Unfortunately, many of the oldest examples have been 
mined continuously or reopened in more modern times to mine remaining lower-grade ore. The 
Laurion mines, about 40 km south of Athens, Greece (Figure 3-4), were first mined about 2,000 

to 1,500 B.C., but were mined most actively from 600 to 300 B.C. (Shepherd 1993 [157425], p. 
75). These silver and lead mines are in a gently dipping sequence of mica schists and marble, 
with sulfides occurring along the contacts. Shafts 1.251.4 m by 1.51.9 m were sunk up to 111 
m deep (Shepherd 1993 [157425], p. 17). Underground workings were 140 km in length; tunnels 
averaged 1 m in width and 1.75 m in height (Shepherd 1993 [157425], pp. 1718). Ore zones 
were mined out by underhand stoping, which left large cavities a couple of meters high and a few 
meters in diameter. Pillars of inferior ore-grade rock supported these cavities (Shepherd 1993 
[157425], p. 25). 
Bronze-age mining of metal also occurred at the Great Orme Copper Mine in Wales. Charcoal 
recovered from the early workings dates at 1,000 to 2,000 B.C. In 1849, miners broke into a 
cavern nearly 40 m long, which contained stone hammers, most likely from the Bronze Age. 
The cavern, mined into limestone, had stood open for nearly 4,000 years (Llandudno Museum 
1998 [157526]). 
Underground mining was common during the Roman Empire, and the size and state of 
preservation of the mines not destroyed by subsequent mining are fairly similar. Shepherd (1993 
[157425]) and Davies (1935 [157421]) present locations and descriptions for most of these 
mines. In addition to mining for metals, the Romans created large tunnels to transport water. 
For instance, the aqueduct at Tresmines, Portugal, is 60 m wide, 80 m high and 480 m long; at 
Corta das Coras, the tunnel is 100 m wide, 100 m high, and 350 m long (Shepherd 1993 
[157425], p. 17). 
Buddhist monks carved temples into caves in the fractured Deccan basalts of west-central India, 
from approximately the second century B.C. until the tenth century A.D., with most excavated in 
the late fifth or early sixth century A.D. (Behl 1998 [156213], pp. 27, 39). There are 31 caves at 
Ajanta, India, carved along a 550 m long, horseshoe-shaped gorge of the Waghora River. Each 
temple originally had steps carved into the rock leading up to it, but only Cave #16 still has a 
vestige of steps. The monsoonal climate has destroyed the exterior stone structures exposed to 
the elements, but subterranean openings have been well preserved in spite of the climatic effects. 
Similar Buddhist caves, from the sixth through the tenth centuries A.D., are preserved at Ellora 
and from the ninth century A.D. (Jain caves) at Sittanavasal, India (Behl 1998 [156213], p. 39). 
The cross-sectional dimensions of most of the temples at Ajanta are larger than those proposed 
for a mined geologic repository. For example, Cave #10 is 30.5 m  12.2 m. Cave #2 has a 
verandah of 14.10 m  2.36 m, a main hall of 14.73 m  14.5 m, and a shrine of 4.27 m  
3.35 m. Cave #16 has a verandah of 19.8 m  3.25 m and a main hall of 22.25 m on a side with a 
height of 4.6 m. In spite of these large sizes, there is no reported collapse. As in the case of the 
Egyptian tombs, most of the Ajanta paintings appear to have suffered some water damage and 
vandalism (Behl 1998 [156213], pp. 234236). 
During the second through eleventh centuries A.D., the Christians of Cappadocia, Turkey, 
excavated underground cities and churches. One of these cities, Derinkuyu, covered 
approximately 4 km2 and had an estimated 15,000 to 20,000 inhabitants (Toprak et al. 1994 
[157429], p. 54) during much of the first millennium A.D. As of 1994, eight levels of ancient 
habitation had been discovered. Access to the underground cities was by way of narrow 
passageways that could be closed by rolling a 1.5 m diameter millstone across the opening 

(Figure 3-5). The excavated rooms were generally several meters across and more than 10 m 
long. 
The geology of Cappadocia (Toprak et al. 1994 [157429], pp. 811) is similar to that of southern 
Nevada (Sawyer et al. 1994 [100075]), although the Cappadocia region is more seismically 
active. In both regions, the late Tertiary section is composed of a thick sequence of silicic 
volcanic rocks. At Yucca Mountain, the host rock for the repository is a densely welded, quartz 
latite ash-flow tuff that formed about 11.6 Ma, whereas the underground cities of Cappadocia are 
situated in a partially welded, rhyolite ash-flow tuff that formed about 4 to 9 Ma. The difference 
in welding at Yucca Mountain and the underground cities of Cappadocia results in markedly 
different fracture density and engineering properties. Fracture density, which is a major variable 
contributing to underground collapse, is much lower in the underground cities. Ground support, 
which would be carefully engineered at Yucca Mountain, was never used in the underground 
cities. Thus, the fact that there has been no collapse in the underground cities of Cappadocia 
during the past 1,500 to 1,800 years suggests that excavations in tuff should be stable for long 
periods of time if undisturbed. Stability of unsupported openings would be favored in tuffs of a 
low degree of welding and fracturing. 
Churches were excavated into the tuff north of the underground cities at Goreme, in Cappadocia, 
during the ninth to thirteenth centuries A.D. (Toprak et al. 1994 [157429], p. 53). All but one of 
these show no evidence of collapse. The exception is a collapse of a cliff face that exposes part 
of the inside of one church. The interior portions of the church are still in excellent condition, 
and their painted walls and ceilings within are well preserved except for spallation and vandalism 
(Stuckless 2000 [151957], p. 22). 
Some of the underground openings excavated into the tuffs of Cappadocia are still used as 
dwellings. There are at least two other places where underground excavations are still used as 
dwellings. In Tunisia, 20 to 40 km south of the city of Gabes, ten underground villages, some of 
which date back nine centuries, are excavated in limestone (Golany 1983 [157422], pp. 56). 
The limestone is composed of poorly indurated layers approximately 2 m thick, which are easily 
mined out, along with better indurated layers of similar thickness. Room sizes are typically 2 to 
2.5 m on a side, with flat ceilings that may have a supporting column in the center. Similarly, in 
northern China, thick deposits of slightly indurated loess exist, which could be easily excavated. 
However, the internal structure of loess is such that it can form vertical cliffs as much as 30 m in 
height. The underground dwellings accommodate more than 10 million people, who farm the 
land above their houses (Golany 1983 [157422], p. 13). 
Although all the examples given so far either lack ground support or utilize only unmined pillars, 
examples do exist of wooden ground support. Around the beginning of the second century A.D., 
the Roman Emperor Hadrian mandated the use of wooden supports in all mines (Shepherd 1993 
[157425], p. 25). Shepherd (1993 [157425], p. 26) provides a discussion of some examples, but 
does not comment on the stability of openings that were shored up. Tombs in China provide a 
different kind of example. Sixteen emperors from the Ming Dynasty (1368 to 1644 A.D.) were 
buried in tombs excavated in rock near Beijing. The earliest of the tombs has 32 sandalwood 
pillars 1.17 m in diameter; all are still intact and sturdy (Golany 1989 [157423], pp. 2122). 

3.4 UNDERGROUND OPENINGS AFFECTED BY TEMPERATURE 
The foregoing descriptions show that both natural and manmade underground openings maintain 
stability well in an undisturbed setting. In fact, many of the examples given, as well as several 
mines not discussed, have probably been subjected to significant seismic shaking. Further 
discussion of seismic effects on underground openings is provided in Section 14. 
The stability of underground openings can also be affected by temperature. An example of 
thermal stresses causing rockfall around rock bolts in a heated area occurred at Linwood Mining 
Companys limestone excavations (Simmons 2002 [157578], SN-LBNL-SCI-108-V2, pp. 7, 8). 
Linwood has excavated limestone adjacent to the Mississippi River downstream from Moline, 
Illinois, since World War I for processing in a kiln. The mine started as a surface quarrying 
operation, but as excavation progressed, the mine was converted to an underground room and 
pillar operation. The elevation of the underground workings is lower than the Mississippi River. 
The company started venting the kiln exhaust underground in 1971 as part of a solution for 
controlling dust emissions from the kiln (Simmons 2002 [157578], SN-LBNL-SCI-108-V2, pp. 
7, 8). To do this, a 96-acre portion of the mine was nominally mined with 30 ft  30 ft pillars 21 
ft high. This portion was walled off from the active workings. Exhaust from the kiln is vented 
to these workings at 400oF (204C), leaving the dust behind for later collection. 
The mining company adds bolts and mesh when a karstic depression is encountered, but 
otherwise the mine is essentially unsupported. Perhaps for this reason, steel-bar rock bolts were 
placed near the entry of the exhaust. After some period of venting, the rock near the exhaust 
vent broke out, leaving the bolts that had been emplaced in the rock, with the bottom 5 feet or so 
of the bolts, surrounded by air. It was suggested that the surrounding rock had probably fallen 
out because heat was transferred up the rock bolt faster than it was transferred through the rock, 
which resulted in a thermal stress that caused failure for a rock with an unconfined compressive 
strength of 18,000 psi (~125 MPa) (Simmons 2002 [157578], SN-LBNL-SCI-108-V2, pp. 7, 8). 
3.5 SUMMARY 
In Section 3, numerous examples are provided of the stability of natural and man-made 
underground openings for millennia or longer under undisturbed conditions. However, an 
inherent bias is reflected in the studies because of the difficulty of determining the relative 
percent of openings that remain versus those that have collapsed. It is more difficult to evaluate 
the cause of collapse of such openings, whether by human interference or natural causes. The 
ability of underground openings to remain open and stable under ambient conditions depends on 
a number of variables, including: (1) rock strength; (2) the size, shape, and orientation of the 
opening; (3) orientation, length, and frequency of fracturing; and (4) effectiveness of ground 
support. Radiometric dating of cave floor minerals at Carlsbad Caverns and Lechuguilla Cave 
indicates that natural openings larger than those proposed for repository drifts at Yucca 
Mountain have remained open for millions of years. Collapse of the roof of an opening tends to 
occur where the fracture density is high and the overburden is thin, as is the case with some lava 
tubes. Factors that contribute to the size of a block falling are fracture spacing, which, in turn, 
depends on rock type and texture, and the size and shape of the opening. 

The oldest examples of stable man-made openings are Neolithic flint mines dating from 4,000 to 
3,000 B.C. However, numerous Roman mines and some aqueducts remain intact that tended to 
have been constructed of a similar size and now exhibit the same state of preservation. These 
and other examples demonstrate that both natural and man-made underground openings can exist 
for thousands of years in a wide variety of geologic settings, even with minimal or no 
engineering. 

NOTE: Areas such as this have no obvious roof blocks on the floor of the 
cavern or holes in the ceiling from which blocks might have fallen. 
Source: Simmons 2002 [157578], SN-LBNL-SCI-108-V2, p. 6. 
Figure 3-1. Photograph of Fairyland in Carlsbad Caverns, New Mexico 
(a) 
Source: (a) Undara Experience 2001 [157515] and 
(b) USGS 2000 [157517]). 
Figure 3-2. Photographs of (a) Lava Tube in Undara, Australia, and (b) Nahuku Lava Tube in Hawaii 

Source: Simmons 2002 [157578], SN-LBNL-SCI-108-V2, p. 6. 
Figure 3-3. Photographs of the Nubian Limestone That Hosts the Tombs in the Valley of the Kings, Egypt 
NOTE: The roof is formed by mica schist and the floor by marble. Ground support appears 
to be modern because older reports make no mention of either wood or cement. 
Source: Gill 2001 [157516]. 
Figure 3-4. Mined-Out Cavern in the Laurion Mines, Greece 

NOTE: The millstone is about 1.5 m in diameter. 
Source: Stuckless 2000 [151957], Figure 13. 
Figure 3-5. Photograph of a Room in the Underground City of Kaymakli, Turkey 

4. ANALOGUES TO WASTE-FORM DEGRADATION 
4.1 INTRODUCTION 
Many variations of waste form types may be emplaced within a potential repository at Yucca 
Mountain. However, most of the waste will be spent fuel in the form of UO2, with the remaining 
10% or so being encapsulated in borosilicate glass resulting from vitrification of defense highlevel 
nuclear waste. These waste forms are thermodynamically unstable under wet, oxidizing 
conditions (DOE 2001 [153849], 4.2.6.1). For this reason, quantification of the degradation 
modes and dissolution rates that determine the source term for performance assessment is 
extremely important. 
Analogue studies may contribute to understanding long-term waste form degradation processes 
through the record left behind in secondary minerals and groundwater. Many of the published 
analogue studies of waste form degradation focus on dissolution of uranium under reducing 
groundwater conditions. This is because most of the geologic waste disposal configurations of 
other nations involve saturated, reducing conditions. Sketches of the most important and wellstudied 
of these analogue sites were provided in Section 13 of the Yucca Mountain Site 
Description (CRWMS M&O 2000 [151945]). As a whole, the sites with reducing groundwater 
chemistry have limited applicability to conditions that would be expected to occur at a potential 
Yucca Mountain repository, which is located in an unsaturated oxidizing environment. 
However, in some instances, information from such analogue studies as these can still provide 
valuable insights into the processes of waste form degradation. Section 4 relies to the extent 
possible on information derived from oxidizing environments, but relevant information from 
examples in reducing environments is included to illustrate general principles of waste form 
dissolution and potential criticality. 
Section 4.2 provides a conceptual basis for waste form degradation. Section 4.3 discusses 
analogues relevant to spent-fuel dissolution rates. Section 4.4 addresses the formation of 
secondary minerals that may immobilize uranium and fission products. Section 4.5 briefly 
covers radiolysis and Section 4.6 briefly covers nuclear criticality of the waste form. Section 4.7 
summarizes studies of analogues to glass waste forms. Section 4.8 is a summary of the topics 
discussed. 
4.2 WASTE-FORM DEGRADATIONCONCEPTUAL BASIS 
4.2.1 Overview of Conceptual Basis 
Radionuclide release from the waste forms that would be emplaced at Yucca Mountain is a 
three-step process requiring: (1) degradation of the waste forms, (2) mobilization of the 
radionuclides from the degraded waste forms, and (3) transport of the radionuclides away from 
the waste forms (DOE 2001 [153849], Section 4.2.6.1). Water strongly influences all three 
processes. 
As described in the S&ER (DOE 2001 [153849], Section 4.2.6.1) radionuclide release begins 
after breach of the waste package and the ingress of air. If the breach is early in the lifetime of 
the repository, the waste may still be highly radioactive and physically hot. The thermal output 

of hot waste packages, particularly from commercial spent fuel, will limit groundwater access at 
early times. When water enters the package, the rate of water inflow and evaporation will 
determine when and if water accumulates. During this period, gamma radiolysis (radiationinduced 
decomposition) of the humid air within the package may cause production of nitric acid, 
which could condense into any accumulated water. If the breach is late, radiation levels and heat 
will be much lower, and evaporation and radiolytic acid production will be less important. 
During either period, water may enter the package either as water vapor or as liquid. The 
dissolved constituents in the groundwater entering the package may have a significant effect on 
in-package chemistry only if evaporation has concentrated them by orders of magnitude. This is 
unlikely to occur unless the waste package is breached only at the top and large amounts of water 
enter and evaporate within the package. During the late period, there is no water transport of 
groundwater species or radionuclides out of the package. 
If the package overflows, or if holes in the bottom of the waste package allow flow-through, 
fresh water will dilute the groundwater components, and water-based radionuclide releases may 
begin. The release of radionuclides does not begin until after the breach of the cladding (for 
spent fuel). Chemistry within the package is important because it influences the rate of 
degradation of the package and waste forms (including cladding), and it determines the mobility 
of radionuclides as dissolved or colloidal species. Films of stagnant, concentrated, acidified 
groundwater are considered the worst possible scenario for degradation, because they do not 
inhibit oxygen and carbon dioxide transport and may support localized corrosion of the cladding 
and waste. Such films, however, do not support significant mobilization and transport of 
radionuclides and are only possible at times when there is an exact balance of water inflow and 
evaporation. 
As stated previously, most of the many waste form types that may be emplaced within a 
repository are thermodynamically unstable under wet, oxidizing conditions (DOE 2001 
[153849], Section 4.2.6.1). Uranium dioxide fuels will oxidize and hydrate, and glass waste 
forms will react with water to form clays, zeolites, and oxides. The rate of these reactions, 
however, will in most cases be quite slow and may be limited by the rate that reactants such as 
oxygen and water can be transported to the waste form surface. Although a few radionuclides 
such as cesium and iodine may concentrate between the fuel and cladding during reactor 
operation, most of the radionuclides will be incorporated within the various waste forms and 
cannot be released from the waste package until the waste forms degrade. 
Once the waste forms degrade, radionuclides as dissolved species and suspended particles may 
be mobilized by advection or diffusion. Larger particles settle out of solution or are filtered out 
by being trapped in small openings. Only after gross failure of the package will these larger 
particles fall or wash out of the package. Particles in the colloid size range, however, can remain 
suspended and may travel significant distances. The concentration of radionuclides associated 
with colloids is limited by the colloid concentration and radionuclide carrying capacity of the 
colloids (DOE 2001 [153849], Section 4.2.6.1). The concentration of dissolved species is 
limited by the elemental solubility of the radionuclide within the local environment. 

4.2.2 Spent-Fuel Dissolution in an Oxidizing Environment 
Many laboratory studies attempt to measure parameters that can be used to determine the rate of 
spent fuel dissolution under repository disposal conditions. These studies use either spent fuel 
itself, uranium dioxide (as an analogue for spent fuel), or uraninite as a natural analogue. 
Although the uraninite structure can accommodate some degree of oxidation, in highly oxidizing 
aqueous environments uraninite is unstable and decomposes (Finch and Ewing 1992 [113030], p. 
133). Secondary uranyl (U+6)-bearing phases precipitate on the surface of the corroding 
uraninite, and a rind of corrosion products forms. The impurities often contained in uraninite 
affect its thermodynamic properties, the rate of uraninite alteration, and the composition of the 
corrosion products (Finch and Ewing 1991 [105591], p. 392). Studies that have examined the 
dissolution of uraninite under oxidizing conditions have found that the dissolution rate was 
diminished by the presence of thorium, lead, and rare-earth-element impurities in the uraninite 
(Finch and Ewing 1992 [113030], p. 133). Compared to uraninite, spent fuel has a lower content 
of these impurities (Finch and Ewing 1992 [127908], p. 466) and on this basis might be 
considered to dissolve more rapidly. 
Most of the uranium released to solution during the dissolution of UO2 combines with ions in 
water to form secondary alteration phases. Both natural and experimental uranium systems 
display a paragenetic sequence of mineral phase formation that is characterized by the following 
general trend (Stout and Leider 1997 [100419], Section 2.1.3.5): 
UO2 . uranyl oxide hydrates . alkali and alkaline-earth uranyl oxide hydrates . 
uranyl silicates . alkali- and alkaline earth uranyl silicates + palygorskite clay. 
Specifically, mineralization in the experimentally determined paragenetic sequence of alteration 
phases is: 
UO2 . dehydrated schoepite (UO32H2O) . compreignacite K2(UO2)6O4(OH)68H2O 
+ becquerelite (Ca(UO2)6O4(OH)68H2O) . soddyite ((UO2)2SiO42H2O) . 
boltwoodite (K(H3O)(UO2) SiO4) + uranophane (Ca(UO2)2Si2O76H2O) + palygorskite 
clay (Wronkiewicz et al. 1996 [102047], p. 94). 
Thus, the uranyl oxide hydrates are common initial corrosion products of uraninite during 
weathering. In the presence of dissolved silica, these early phases alter to uranyl silicates, most 
commonly soddyite and uranophane. The phases that form depend on the chemical composition 
of the waters with which the uraninite is in contact, which in turn depends on the mineralogy of 
the surrounding host rocks and the oxidation potential of the hydrologic environment. The 
experimentally determined mineral sequence appears to be controlled by precipitation kinetics 
and is nearly identical to secondary uranium phases observed during the weathering of naturally 
occurring uraninite under oxidizing conditions, such as that which occurs at the Nopal I uranium 
deposit, Pea Blanca, Mexico (Wronkiewicz et al. 1996 [102047], Figure 7). In laboratory UO2 
tests and in the natural uranium deposits at Nopal I, the alkali- and alkaline-earth uranyl silicates 
represent the long-term solubility-limiting phases for uranium (Stout and Leider 1997 [100419], 
Section 2.1.3.5). Furthermore, at Nopal I, uranium concentrations in groundwater and seepage 
waters ranged from 170 parts per trillion (ppt) to 6 parts per billion (ppb) (Pickett and Murphy 
1999 [110009], Table 2; Table 10.4-1 of this study includes a few higher values  see Section 

10.4 for discussion). In general, the upper part of this range is similar to concentrations seen in 
filtered samples from spent fuel dissolution experiments (Stout and Leider 1997 [100419], p. 
2.1.3.5-4). This added similarity increases confidence that the experiments and the natural 
analogue reactions may simulate the long-term reaction progress of spent UO2 fuel following 
potential disposal at Yucca Mountain. 
Uraninite usually contains radiogenic lead that has in-grown through time (Finch and Ewing 
1992 [127908], p. 466). As a result, the early-formed Pb-poor uranyl oxide hydrates alter 
incongruently to uranyl silicates plus radiogenic-Pb-enriched uranyl oxide hydrates, such as 
curite (Pb2U5O17 4H2O), that may serve to limit the mobility of uranium in nature (Finch and 
Ewing 1992 [127908], p. 466). Curite may also play an important role in the formation of uranyl 
phosphates, which are significantly less soluble than the uranyl silicates and control uranium 
solubility in many groundwaters associated with altered uranium ore (Finch and Ewing 1992 
[127908], p. 465). In the absence of lead, schoepite and becquerelite are the common initial 
corrosion products. The reaction path for the alteration of lead-free uraninite results in the 
formation of uranyl silicates. Thus, the long-term oxidation behavior for ancient, lead-bearing 
uraninite is different from that of young, lead-free uraninite, which is more similar to spent fuel. 
Because the presence of lead effectively reduces the mobility of uranium in oxidizing waters, the 
concentration of uranium in groundwaters associated with oxidized uranium ore deposits will 
depend in part on the age of the primary uraninite (Finch and Ewing 1992 [113030], p. 133). 
In summary, the paragenesis of uraninite alteration phases depends on the age of the primary 
uraninite, the mineralogy of surrounding host rocks, and on groundwater composition, pH, and 
redox potential. In a general oversimplification, the progression of phases of uraninite alteration, 
in the absence of radiogenic lead in-growth, will be to uranyl silicates, culminating in 
uranophane in an oxidizing environment. Numerous compositional variations are caused by 
trace elements present in the system. The composition of schoepite is often used to represent an 
alteration product in models of spent fuel alteration, but this is an oversimplification, based on 
observations in nature. As shown by Finch and Ewing (1992 [113030], p. 144), the formation of 
intermediate-phase schoepite may be favored early during the corrosion of uraninite. Schoepite is 
not, however, a long-term solubility-limiting phase for oxidized uranium in natural groundwaters 
containing dissolved silica or carbonate (e.g., the type of groundwaters at Yucca 
Mountain). 
Despite the analogy between uraninite and spent fuel, there are important differences between 
the two. For one thing, spent fuel is artificially enriched in 235U and contains nuclear fission 
products that are not present in uraninite; in contrast, uraninite contains a higher proportion of 
nonradiogenic trace element impurities. Also, the thermal history of spent fuel, unlike that of 
natural uraninite, may cause lattice and structural crystallization defects in the spent fuel that are 
not present in the uraninite. In addition, geologically old uraninite contains in-grown radiogenic 
lead, which would not be found in younger uraninite or in spent fuel. Section 4.3 presents the 
general dissolution path of uraninite, and by analogy spent fuel, under oxidizing conditions. 
4.3 ANALOGUE STUDIES RELATED TO WASTE-FORM DISSOLUTION RATES 
The remaining issues of most relevance to the behavior of spent fuel in a repository that could be 
addressed by natural analogues are dissolution and radionuclide release (Section 4.3), 

radionuclide retardation by secondary alteration products (Section 4.4), radiolysis (Section 4.5), 
and criticality (Section 4.6). 
4.3.1 Fission-Product Tracer Method 
Rates of UO2 dissolution can be quantified by measuring the amount of fission product released 
from the uraninite and using this as a tracer. Concentrations of this tracer in the rock or in the 
groundwater in the vicinity of the uraninite are proportional to the dissolution rate, assuming that 
the tracer is released from the uraninite only by dissolution (Curtis 1996 [157497]; Curtis et al. 
1994 [105270]; 1999 [110987]). The tracers used for this method are 99Tc in rock, or its stable 
daughter 99Ru when technetium has decayed to insignificant amounts, and 129I in groundwater. 
There are several uncertainties in the modeling and assumptions made in this approach, but some 
consistency is apparent in the results obtained from different uranium orebodies when using the 
same isotopic system. For example, using the 99Tc tracer at Oklo, Gabon, and at Cigar Lake, 
Canada, provided average release rates of 1.5  106 per year and 1.1  106 per year, 
respectively (Curtis 1996 [157497], p. 145). However, different rates are obtained when using 
129I as a tracer. Applying this tracer at Cigar Lake provided release rates of between 9  109 and 
3  10-10 per year, which are 2 to 4 orders of magnitude less than the values obtained using the 
99Tc tracer. 
Curtis et al. (1994 [105270]) used measurements of 99Tc, 129I, 239Pu, and U concentrations in 
rock from uranium deposits at Cigar Lake and Koongarra to estimate radionuclide release rates 
from uranium minerals. At Koongarra, Australia, release rates appear to have been faster (107 
per year; Curtis et al. 1994 [105270], p. 2234) than at Cigar Lake, where model-dependent 
release constants from the uraninite-bearing rocks were <5  108 per year (Curtis et al. 1994 
[105270], p. 2234), producing small deficiencies of 99Tc and larger ones of 129I. The inferred 
differences in radionuclide release rates are consistent with expected differences in uranium 
mineral degradation rates produced by the differing hydrogeochemical environments at the two 
sites. In the Cigar Lake ore zone, low uraninite solubility in a reducing environment and small 
water flux through impermeable rock would inhibit the rate of uraninite degradation and, thus, 
the rate of radionuclide release. At Koongarra, higher mineral solubilities induced by higher 
oxidation potentials, higher aqueous concentrations of carbonate and phosphate, and greater 
water fluxes would be expected to produce higher rates of uranium mineral degradation. Curtis 
et al. (1999 [110987], p. 284) note that the consistency of 239Pu/U and 99Tc/U ratios in bulk rock 
suggests that the redistribution processes observed at Cigar Lake are highly localized and do not 
result in large-scale losses or gains of these nuclear products from the deposit as a whole. The 
fission-product tracer method could be applied to water samples collected at Pea Blanca 
(Section 10.4). While this method clearly has potential for quantifying UO2 dissolution under 
natural conditions, the method has yet to be refined and differences between results for the two 
tracers explained. Besides this fission-product tracer method, there is no other technique for 
quantifying directly long-term uraninite dissolution rates in natural analogue studies. 
4.3.2 Dissolution of Oklo Uraninite 
Application of the fission-product tracer method has not been reported for Oklo, but Oklo 
provides a unique record of uranium and fission-product retention. Because parts of the Oklo 
orebody achieved nuclear criticality as a result of highly enriched concentrations of 235U, Oklo 

uraninite contains significant quantities of fission products or their stable daughters, directly 
equivalent to those present in spent fuel. In this regard, Oklo is unlike any other known uranium 
deposit. A photograph of one of the reactor zones is shown in Figure 4-1. 
There are, however, some differences between Oklo uraninite and spent fuel. For one thing, 
Oklo contains lower concentrations of fission products than does spent fuel. Also the 
temperature of reaction (400o to 600oC; for a discussion of temperatures, see Zetterstrm 2000 
([157501], p. 13) and power density were somewhat lower than in a reactor, and the duration of 
criticality at Oklo (on the order of 0.1 to 0.8 Ma; Louvat and Davies 1998 [125914], p. 140) was 
much longer than the lifetime of reactor fuel. Recognizing these differences, several large-scale 
analogue investigations have taken place at Oklo, and much relevant information has been 
obtained, including semiquantitative information on the fate of radionuclides contained in the 
orebody. 
These analogue investigations (e.g., Louvat and Davies 1998 [125914]; Gauthier-Lafaye et al. 
2000 [157499]) have revealed that when the Oklo reactor zones were cooling after periods of 
criticality, some dissolution of the uraninite and elemental remobilization occurred. However, 
the limited extent of this remobilization is indicated by the the fact that more than 90% of the 
uranium fuel has remained in the same spatial configuration since criticality (Miller et al. 2000 
[156684], p. 81). This implies that uranium has been almost fully retained within the uraninite 
minerals. The disposition of some performance assessment-relevant elements and other elements 
in the reactor zones at Oklo is provided in Table 4-1. The transuranic elements neptunium, 
plutonium, and americium were all formed in situ within the uraninite during criticality, and their 
stable daughters have also been retained due to their compatibility with the crystal chemical 
structure of their host or in inclusions in the uraninite. Other radiogenic elements, which were 
less compatible with the uraninite host (e.g., Cs, Rb, Sr, Ba) have been partially or totally lost by 
diffusion from the uraninite. Some elements (e.g., Tc, Ru, Rh, Pd), however, migrated only short 
distances and were totally retained within the clay matrix enclosing the reactors. Data for other 
elements indicate clear deficiencies in the noble gases, halides, and lead (possibly resulting from 
volatilization) and suggest that some minor loss from the system has occurred for other elements. 
Because the reactions ended nearly two billion years ago, the short-lived radionuclides have 
decayed to more stable daughter nuclides. Analysis of the behavior of these short-lived 
radionuclides is problematic. According to Brookins (1978 [133930], p. 309), Pu, Np, and Am 
were likely retained within the reactor, while Bi and Pb would have been redistributed locally 
without substantial migration (Brookins 1978 [133930], p. 309). Most geochemical observations 
at Oklo support these predictions to varying degrees. Curtis et al. (1989 [100438], p. 57) 
conclude that the retention of fission products is related to their partitioning into uraninite or 
secondary mineral assemblages. Those fission products that partitioned into the secondary 
mineral assemblages were largely lost over time, pointing to the importance of small uraninite 
grains in controlling the chemical microenvironment. 
It is important to note that most of the observed uraninite alteration at Oklo occurred under 
hydrothermal conditions. Little uraninite-groundwater interaction has taken place at present-day 
ambient temperatures, except at the shallow Bangomb reactor zone (Smellie et al. 1993 
[126645], p. 144). In summary, the Oklo natural analogue investigations indicate that the 
kinetics of UO2 dissolution, either as uraninite or spent fuel, are exceedingly low under reducing 

conditions expected in the near field of some repositories. While dissolution rates cannot be 
quantified readily from natural analogue data, the abundance of naturally occurring uraninite that 
is nearly 2 billion years old at Oklo indicates its stability in the natural environment. 
4.4 ANALOGUE STUDIES RELATED TO IMMOBILIZATION BY SECONDARY 
MINERALS 
Laboratory experiments have shown that UO2 dissolution is accompanied by the formation of 
secondary phases on the fuel surface and that these corrosion products can passivate further 
dissolution (Wronkiewicz et al. 1996 [102047], p. 79). At the temperature and time scales of 
laboratory experiments, these phases are amorphous. However, natural sites where uraninite 
accumulations occur and where dissolution has taken place over long time periods could provide 
insights into the structure and mineralogy of the secondary passivating phases, and indicate 
whether they have been able to prevent further mobilization of radionuclides. 
4.4.1 Shinkolobwe, Zaire 
The 1,800 Ma Shinkolobwe uranium orebody in Zaire (at the time of study) was the subject of a 
comprehensive investigation regarding the corrosion products of uraninite (Finch and Ewing 
1991 [105591]). The Shinkolobwe deposit weathers under oxidizing conditions in a monsoonaltype 
environment where rainfall is above 1 m per year, thus providing more aggressive 
hydrochemical conditions than might be expected at a repository. At Shinkolobwe, the uraninite 
is coarsely crystalline and lacks many of the impurities, such as thorium and rare earth elements, 
found in other uranium deposits. This lack of impurities led Finch and Ewing (1991 [105591], p. 
391) to suggest that the thermodynamic stability of the Shinkolobwe uraninite might closely 
approximate spent fuel. 
The deposit has been exposed at the surface since the Tertiary (< 60 million years), and extensive 
weathering has altered or replaced much of the original uraninite. Uranium (VI) mineralization 
occurs along fracture zones where meteoric waters have penetrated up to 80 m deep or more. 
Uraninite crystals at Shinkolobwe are commonly surrounded by dense rinds of alteration 
minerals, mostly uranyl oxyhydroxides, as well as uranyl silicates and rutherfordine, a uranyl 
carbonate (UO2CO3). Uranyl phosphates are also common within fractures throughout the host 
rocks, but are rare or absent from corrosion rinds. 
Uranyl minerals comprising the corrosion rinds that surround many uraninite crystals undergo 
continuous alteration. This alteration occurs through repeated interaction with carbonate- and Sibearing 
groundwater combined with periodic dehydration of (especially) schoepite and 
metaschoepite (Finch and Ewing 1991 [105591], p. 396). Such alteration occurs along small 
(approx. 0.1 to 1 mm) veins within the corrosion rinds. There is a general decrease in grain size 
as alteration proceeds, most commonly along veins. Schoepite, however, is not observed to reprecipitate 
where in contact with dehydrated schoepite (Finch and Ewing 1991 [105591], p. 396). 
Thus, while the formation of schoepite early during the corrosion of uraninite may be favored, 
schoepite is not a long-term solubility-limiting phase for oxidized uranium in natural 
groundwaters containing dissolved silica or carbonate (e.g., the type of groundwaters at Yucca 
Mountain). 

Over 50 secondary uranyl phases were identified from the alteration of the Shinkolobwe 
uraninite. It was concluded that uraninite transforms to Pb-U oxide hydrates and then to uranyl 
silicates if sufficient silica is present in the system. Alteration of Proterozoic (~2400 to 700 Ma) 
uranium deposits such as Shinkolobwe introduce the important Pb-bearing phases, such as curite, 
which play a role in development of other stable phases in the system. Because of the very 
young age of repository spent fuel, radiogenic lead would not be present at Yucca Mountain for 
helping to immobilize spent-fuel elements. 
4.4.2 Secondary Phases of Uranium Found at Nopal I, Pea Blanca 
See Section 10.4 for a description of the Nopal I site. At Nopal I, uraninite occurs in rhyolite tuff 
in a semi-arid environment, where it has been exposed to oxidizing groundwater conditions with 
nearly neutral pH. Uranium was initially deposited as uraninite at Nopal I approximately 8 Ma 
(Pearcy et al 1994 [100486], p. 729). Geologic, petrographic, and geochemical analyses indicate 
that primary uraninite at Nopal I has been almost entirely altered to hydrated oxides and silicates 
containing uranium in the oxidized (uranyl) form. Because of its young geologic age, the deposit 
is low in radiogenic lead. The sequence of formation of uranyl minerals by alteration of 
uraninite at Nopal I is shown in Figure 4-2 and is similar in many geologically young uranium 
deposits located in oxidizing environments. 
Leslie et al. (1993 [101714]) and Pearcy et al. (1994 [100486]) compared the alteration of 
uraninite at Nopal I to laboratory experiments of degradation of spent nuclear fuel potentially to 
be disposed of at Yucca Mountain, Nevada. They found that uraninite from the Nopal I deposit 
should be a good natural analogue to spent nuclear fuel because long-term experiments on spent 
fuel show alteration parageneses, intergrowths, and morphologies that are very similar to those 
observed at Nopal I (Wronkiewicz et al. 1996 [102047]). Oxidation of the uraninite at Nopal I 
has produced an ordered suite of minerals, first forming schoepite, a uranyl oxyhydroxide, 
followed by hydrated uranyl silicates, such as soddyite (Figure 4-2). A higher calcium 
abundance, relative to other cations in Nopal I groundwater, supports the formation of 
uranophane, a hydrated calcium uranyl silicate as the dominant secondary uranium phase. 
Because of the abundance of calcite at Yucca Mountain, uranophane would be a potential 
secondary phase there as well. In comparison, laboratory experiments find that the general trend 
is to form mixed uranium oxides, followed by uranyl oxhydroxides, and finally uranium silicates, 
mostly uranophane with lesser amounts of soddyite (Wronkiewicz et al. 1996 [102047], p. 92). 
In addition, uraninite at Nopal I has a low trace-element component (average of 3 wt%) that 
compares well with that of spent nuclear fuel (typically < 5 wt% (Pearcy et al. 1994 [100486], p. 
730)). The young age of the Nopal I deposit is another similarity to Yucca Mountain with 
respect to the absence of Pb-bearing secondary phases. 
4.4.3 Secondary Phases at Oklobondo 
In the first detailed study of the Oklobondo natural fission reactor in Gabon, which corresponds 
to the southern extension of the Oklo deposit (Figure 4-3), Jensen and Ewing (2001 [157500]) 
presented a history of uraninite alteration at that site showing complex mineralogical and textural 
relationships. The Oklobondo reactor is the deepest of the 16 natural reactors (Figure 4-3). It is 
situated at the base of a 2.5 m deep synform in the FA sandstone of the (Figure 4-3) 
Francevillian Series. The Oklobondo reactor zone (RZOKE) developed at the interface 

between overlying brecciated high-grade uranium-mineralized FA sandstone and underlying 
bitumen-rich black shale of the FB Formation (Figure 4-3). RZOKE is relatively small (2.7 m 
wide and > 4 m long) and contains a ~ 55 cm thick reactor core (Jensen and Ewing 2001 
[157500], p. 32). 
Criticality in RZOKE was facilitated by fixation and reduction of oxidized uranium by liquid 
bitumen and precipitation of uraninite into a dense microfracture network in the FA sandstone. 
The brecciation of the host rock may have been increased by overpressure created by the 
accumulation of hydrocarbon gases during diagenetic maturation of oil introduced into the FA 
sandstone. Chemical analyses and model estimates suggest that the ore grade at criticality at 
RZOKE was on the order of 20 wt% uranium. Operation of the reactor caused extensive 
dissolution of the FA sandstone and hydrothermal alteration of the black shale of the FB 
Formation. The sandstone dissolution was the major process that led to formation of the 2.5 m 
deep reactor synform and the high uranium concentrations (< 90 vol% uraninite) in the core of 
RZOKE (Jensen and Ewing 2001 [157500], p. 59). 
The mineral assemblage of RZOKE is comparable to that reported in the other Oklo reactor 
zones, in that uraninite and Si-rich illite are the major phases in the reactor core, while chlorite 
and illite are the major phases in the so-called argile de pile (reactor clays forming a halo around 
the reactor zone). Galena (PbS) is also a major phase in the reactor zone. Minor coffinite 
(USiO4) and (U,Zr) silicates were also observed in addition to several accessory phases: e.g., 
titanium oxides, La-bearing monazite, sulfides of Cu, Fe, Co, Ni, and Zn, and ruthenium 
arsenides. The minor and trace elements include Th, Zr, Al, P, Ce, and Nd that seldom exceed 
concentrations of 0.1 oxide wt% (Jensen and Ewing 2001 [157500], p. 59). Figure 4-4 shows 
galena, illite, and zircon embedded in a matrix of (U,Zr)-silicate in the center of the RZOKE 
reactor core. 
The acccessory (U,Zr)-silicate, phosphates, and ruthenium arsenides (+ Pb, Co, Ni, and S) were 
of particular importance in secondary retardation of the fissiogenic isotopes (Jensen and Ewing 
2001 [157500], p. 59). The (U,Zr)-silicate contains elevated concentrations of ZrO2, ThO2, 
Ce2O3, and Nd2O3 as compared with the unaltered uraninite. This result suggests that the 
fissiogenic 90Sr, Zr, Ce, and Nd, as well as the Th precursors, were efficiently retarded by the 
(U,Zr)-silicate during their migration in the reactor zone. Lanthanide element fission products 
may also have been retained in rare La-bearing monazite observed in the argile de pile of 
RZOKE. Ruthenium arsenides incorporated fissiogenic Ru, probably including 99Ru, the 
radiogenic daughter of 99Tc. 
The presence of lead-uranyl sulfate hydroxide hydrate, anglesite, partial dissolution of uraninite 
and galena, and the rapid oxidation of pyrite are evidence of a later shift toward oxidative 
alteration conditions in and around the reactor zone. Hence, the slightly oxidizing deep 
groundwaters at Oklobondo may have already reacted with the Oklobondo reactor zone. 
4.5 RADIOLYSIS 
Radiolysis is hydrolysis caused by radiation and results in production of charged species 
(hydrogen and hydroxide ions) that may react to form more mobile species. Radiolysis can affect 
both the waste form and the waste package. Because the waste canister is thinner than in 

previous designs (CRWMS M&O 1999 [107292], Table 5-4), it is not self-shielded, so radiation 
levels at the outside surface of the canister would be higher. However, it is not certain that 
radiolysis will be a problem. The effects of radiolysis in the Oklo ore deposit were discussed by 
Curtis and Gancarz (1983 [124785]). They calculated the alpha- and beta-particle doses in the 
critical reaction zones during criticality and the energy provided to the fluid phase by these 
particles. This energy caused radiolysis of water and the production of reductants (H2) and 
oxidants (O2). The effect of these reductants and oxidants on the transport of radionuclides 
within and outside the reactors has been difficult to quantify. Iron is most reduced in the samples 
that show the greatest 235U depletion. Curtis and Gancarz (1983 [124785], p. 36) suggested that 
the reduction of iron in the reactor zones and oxidation of U (IV) in uraninite was 
contemporaneous with the nuclear reactions and not a later supergene phenomenon of secondary 
enrichment. Curtis and Gancarz (1983 [124785], p. 36) suggested that radiolysis of water 
resulted in the reduction of Fe (III) in the reactor zones and the oxidation of uranium. 
Furthermore, the authors suggested that the oxidized uranium was transported out of the critical 
reaction zones and precipitated through reduction processes in the host rocks immediately 
outside the zones. The reduction processes likely involved organics or sulfides present in the 
host rocks. However, if the host rocks around the natural reactor cores had not contained species 
capable of reducing the oxidized uranium transported out of the cores, the uranium could have 
been transported much further from the critical reaction zones. The important point is that, even 
with intensive radiolysis, very little (only several percent) of the uranium in the natural reactors 
was mobilized (Naudet 1978 [126123], p. 590). 
Jensen and Ewing (2001 [157500], p. 59) noted a migration of Ce from reactor core to rim at 
Oklobondo and suggested that this resulted from radiolysis taking place during reactor 
operation. Cerium, particularly, showed indication of redistribution in the reactor zone, when 
compared with Nd, in the uraninite rim. Because Ce3+ can be oxidized to Ce4+, the difference in 
the behavior of Ce as compared with Nd, results from oxidative alteration. The different 
concentration of Ce in the uraninite rims, as compared with their cores across the reactor zone, 
was produced during reactor operation, perhaps as a result of radiolysis. 
4.6 CRITICALITY 
The uranium deposit at Oklo, which was the site of naturally occurring neutron-induced fission 
reactions over 2,000 Ma, was used as a basis for reviewing conditions and scenarios that might 
lead to nuclear criticality within and outside waste packages in the Swedish waste disposal 
configuration (Oversby 1996 [100485]). The Swedish concept involves disposal in deep granite 
with chemically reducing groundwaters, so the specific conditions are not relevant to those of 
oxidizing environments. Yet in either oxidizing or reducing conditions, the combination of 
simultaneous factors and probabilities required for criticality to occur seems very unlikely. For 
criticality to occur, sufficient 239Pu and/or 235U would need to accumulate together with enough 
water to allow for moderation of neutron energies. This would achieve a state where neutroninduced 
fission reactions could be sustained at a rate significantly above the natural rate of 
spontaneous fission. The chemical and physical conditions required to achieve nuclear criticality 
at Oklo were used by Oversby (1996 [100485]) to estimate the amounts of spent fuel uranium 
that would need to be assembled in a favorable geometry in order to produce a similar reactive 
situation in a geologic repository. The amounts of uranium that must be transported and 
redeposited to reach a critical configuration are extremely large in relation to those that could be 

transported under any reasonably achievable conditions, even under oxidizing conditions. In 
addition, transport and redeposition scenarios often require opposite chemical characteristics. 
Oversby (1996 [100485], p. vii) concluded that the likelihood of achieving a critical condition 
caused by accumulation of a critical mass of uranium outside the canisters after disposal is nil, 
provided that space in the canisters is filled by low solubility materials that prevent entry of 
sufficient water to mobilize uranium. Criticality caused by plutonium outside the canister could 
be ruled out because it requires a series of processes, each of which has an increasingly small 
probability. Criticality caused by uranium outside the canister would require dissolution and 
transport of uranium under oxidizing conditions and deposition of uranium under reducing 
conditions. There is no credible mechanism to achieve both oxidizing and reducing conditions in 
the near-field repository host rock in the long term, after decay of the majority of alpha-active 
isotopes. Thus, the conditional probabilities required to achieve criticality caused by uranium 
make the likelihood that criticality would occur vanishingly low. 
4.7 NUCLEAR-WASTE GLASS ANALOGUES 
Among the natural volcanic glasses, basalt glasses are compositionally the most similar to 
nuclear waste glasses (Lutze et al. 1987 [125923], p. 142). However, there are still substantial 
compositional differences. Basalt glass and nuclear waste glass are similar in silica content, 
alteration products, alteration layer morphologies, and alteration rates in laboratory experiments 
(Grambow et al. 1986 [119228]; Arai et al. 1989 [123814]; Cowan and Ewing 1989 [124396]). 
Basalt glass alteration has been studied in a number of environments including ocean-floor, 
subglacial, hydrothermal and surface conditions (Grambow et al. 1986 [119228]; Jercinovic et al. 
1986 [125289]; Byers et al. 1987 [121857]; Jercinovic and Ewing 1987 [144605]; Arai et al 1989 
[123814]; Cowan and Ewing 1989 [124396]). Inferred alteration rates, as calculated from 
alteration rinds, range from 0.001 m (micrometers)/1,000 years to 30 m/1,000 years (Arai et 
al. 1989 [123814], p. 73). 
Malow and Ewing (1981 [126058]) compared the thermal and chemical stabilities of two 
borosilicate glasses and one glass ceramic to those of three rhyolitic glasses through a variety of 
laboratory tests and observations of natural weathering. They concluded that natural glasses are 
much more stable than waste-form glasses as a result of higher silica contents in the natural 
glasses (74% versus 28 to 50% in waste-form glasses). Tektites (nonvolcanic glass of 
extraterrestrial or impact origin) range in age from ~105 years to 35 Ma and rarely show signs of 
alteration, dehydration, or devitrification (Lutze et al. 1987 [125923], p. 148). Their great 
durability may be a result of their high silica and alumina (~30%) contents and their low (<4%) 
alkali contents (Lutze et al. 1987 [125923], p. 152). 
The compositions of the glasses used in natural analogue studies differ somewhat from 
borosilicate glasses, and this makes a simple analogy dubious for quantitative purposes. High 
silica and alumina contents, along with low alkali contents and low water contents, are favorable 
for long-term preservation. The dissolution rates measured on natural glasses are variable, but 
always very slow. However, natural analogues cannot be used to provide a quantitative estimate 
for the time at which devitrification will begin, or the rate at which it will proceed in the 
repository environment. Natural glass studies do suggest that the rate of devitrification is too 
slow for the process to be significant in the repository. These studies have not, however, 
considered the effect of radiation. It might be possible to obtain relevant data on the radiation

induced effects on glass durability by examining glasses that contain uranium oxides as 
colorants, such as the vaseline glass produced in Germany and Bohemia in the 1800s (Miller et 
al. 2000 [156684], pp. 7576). In all cases, the differences in chemistry between borosilicate 
glass and natural and archeological glasses need to be considered when interpreting analogue 
data. The qualitative evidence from analogues on natural and archeological glasses has added to 
confidence that the glass degradation processes are well understood and has provided upper 
bounding limits to the degradation rates. 
4.8 SUMMARY AND CONCLUSIONS 
The analogue sites located in chemically oxidizing environments are better analogues to 
conditions expected to occur at Yucca Mountain than the more numerous sites located in 
reducing environments. However, some examples from reducing environments may be 
appropriate analogues for processes that would occur under repository conditions in either type 
of chemical environment. Hence, both types of conditions were considered in studying the 
processes relevant to waste form degradation. From the evidence presented in this section, the 
main points are the following: 
The uranium alteration paragenesis sequence at Pea Blanca is a good analogue to 
alteration of uranium oxide spent fuel. The reaction path of alteration of spent fuel at 
Yucca Mountain will be similar to that of geologically young, Pb-free uraninite, with 
schoepite and becquerelite forming as intermediate products followed by uranyl silicates. 
Measurement of the concentration of fission products as tracers in rock and groundwater 
surrounding uraninite provides a satisfactory approach to estimating natural dissolution 
rates. This approach was tested at Cigar Lake and Koongarra under reducing and 
oxidizing conditions, respectively, and the dissolution rate at Koongarra was found to be 
more rapid. Use of the fission-product tracer method has not been reported for Oklo, but 
other lines of evidence indicate that dissolution has been slight under reducing conditions 
at Oklo over the past approximately 2 billion years. Whether deep oxidizing waters at 
Oklobondo have increased the dissolution of uraninite as well as created an oxidized 
suite of minerals is something that could be tested. 
Secondary mineral formation was responsible for incorporating uranium at Shinkolobwe, 
where 50 secondary uranium-bearing phases could be identified. Because of the great age 
of the Shinkolobwe uranium deposit, radiogenic lead-bearing phases played a role in 
sequestering uranium. Lead would not play a role in secondary mineralization of younger 
deposits, nor would it be present in spent fuel at Yucca Mountain. Other secondary 
phases, particularly (U,Zr) silicates, formed stable phases at Oklobondo. Presumably 
radiogenic lead was also present at Oklobondo, because of its approximately 2-billionyear 
age. 
It is uncertain whether radiolysis will be a potential problem around waste packages in the 
current design scenario (in which waste packages are not self-shielded). Under radiolysis 
conditions occurring at the time of reactor criticality at Oklo, only several percent of 
uranium was estimated to have been mobilized for transport from its original site, under 
far more extreme conditions than those anticipated at Yucca Mountain. Likewise at 

Oklobondo, radiolysis effects at the time of reactor operation appear to have been 
confined to rare earth element migration from mineral core to rim. Because liquid water 
in contact with spent fuel is required for radiolysis to occur, the problem seems unlikely 
under either higher- or lower-temperature operating modes for a repository at Yucca 
Mountain. 
Criticality of spent fuel can be triggered by changes in pH as well as by reducing 
conditions. In the study examined, however, criticality was viewed from the standpoint of 
redox conditions. Criticality of spent fuel, either within waste packages or by 
reconcentration of uranium outside of the package, has a very low likelihood because the 
probability of certain processes required to achieve critical conditions occurring 
simultaneously or sequentially renders certain conditions mutually exclusive. 
Although natural glasses are somewhat different in composition from borosilicate nuclear 
waste glass, studies of natural glass alteration indicate that glass waste forms will be stable 
in a repository environment at Yucca Mountain. Higher stability is favored by higher 
silica and alumina content and by lower alkali and water content of the glass. Analogue 
studies have not considered radiation effects on glass over long time periods to confirm 
experimental results showing that radiation has little effect on glass waste stability. 

Table 4-1. Elemental Distribution within Uraninite, Inclusions, and Clays for Elements in the Reactor 
Zones at Oklo 
Element 
Uraninite 
Inclusions 
Clays 
Migration 
Cs 
X 
Rb 
X 
Sr 
X 
Ba 
X 
Mo 
X 
X 
Tc 
X 
X 
Ru 
X 
X 
? 
Rh 
X 
X 
? 
Pd 
X 
X 
? 
Y 
X 
X 
Nb 
? 
? 
Zr 
X 
X 
X 
Te 
X 
REE 
X 
X 
Ce 
X 
Pb 
X 
X 
X 
Bi 
X 
Th 
X 
X 
U 
X 
X 
Np 
? 
X 
Pu 
X 
X 
NOTE: REE-rare earth elements 
Source: Miller et al. 2000 [156684], Table 4.2 (summarized from Blanc 1996 [157498]). 

NOTE: Vegetable matter in lower center is in foreground. Man standing in lower right-center for scale. 
Source: Blanc 1996 [157498], p. III). 
Figure 4-1. Photo of a Reactor Zone at the Oklo Natural Fission Reactor, Gabon 
Source: Modified from Murphy 2000 [157487], Figure 1. 
Figure 4-2. Sequence of Formation of Uranyl Minerals by Alteration of Uraninite 

Source: Gauthier-Lafaye 1996 [157542], Figure 4. 
Figure 4-3. Schematic Cross Section Showing Depth of Oklobondo Natural Fission Reactor in Relation 
to other Oklo Reactors 
NOTE: The (U,Zr)-Silicate is the medium gray colored matrix mineral in which the other 
minerals are encased. 
Source: Jensen and Ewing 2001 [157500], Figure 11e. 
Figure 4-4. Aggregate of (U,Zr)-Silicate, Zircon, Galena, and Illite in the Center of the Oklobondo 
Reactor Core (RZOKE) 

5. CURRENT ENGINEERED BARRIER SYSTEM DESIGN 
5.1 INTRODUCTION 
Section 5 provides a context for Engineered Barrier System (EBS) analogues that are discussed 
in Sections 6 and 7. This section summarizes the key components of the EBS system and 
describes the materials proposed to be used in the construction of these components. Finally, the 
key processes that are expected to occur during the operational life span of the EBS are 
described. This section will potentially be updated as needed, given the future finalization of the 
currently, purposely flexible design. 
5.2 EBS COMPONENTS 
The EBS currently planned for the potential Yucca Mountain repository (Figure 5-1) consists of 
three main components: (1) drip shield, (2) emplacement drift invert, and (3) waste package 
(DOE 2001 [153849], Section 2.4). Because they will affect the performance of the EBS, 
materials included within the waste forms and materials used in the construction of the 
emplacement drifts also are considered in the evaluation of the EBS. The following summary of 
the components of the EBS system is based upon Sections 2.4 and 3 of the Yucca Mountain 
Science and Engineering Report (S&ER) (DOE 2001 [153849]). 
5.2.1 Drip Shield 
The drip shield is designed to serve as a protective barrier, for the length of emplacement drifts, 
that will divert water dripping from the drift walls, thus minimizing direct dripping onto the 
waste packages. The drip shield has the added function of protecting the waste package from 
rock falls from the drift perimeter. These functions require that the drip shield assembly is both 
highly resistant to corrosion and has the structural strength to withstand rock falls. 
The drip shield consists of three separate elements: the drip shield itself, supporting structural 
members, and stands (or feet) upon which the shield assembly rests (Figure 5-2). Current 
design plans call for the drip shield to be manufactured from 15 mm (0.6 in.) thick Titanium 
Grade 7 plates for long-term corrosion resistance. The structural members will be constructed 
using Titanium Grade 24, which has greater strength than Titanium Grade 7. Alloy 22 (see Table 
5.2) will be used for the feet, preventing direct contact between the titanium structural members 
and the carbon steel beams of the invert. 
5.2.2 Drift Invert 
The drift invert is designed to form a stable, level platform along the base of the emplacement 
drift on which the waste package and drip-shield assemblies will be placed. The invert as 
currently planned (DOE 2001 [153849], Section 2.4.1) consists of two components: a steel invert 
structure and a crushed-tuff invert ballast. 
The steel invert structure needs to provide sufficient support for all expected pre-closure 
activities for up to 300 years and must also keep the waste packages in a horizontal position for 
10,000 years after closure. The steel structure consists of transverse and longitudinal support 

beams, which serve to transfer the weight of the waste package and drip shield (along with any 
needed emplacement and maintenance equipment during the initial phases of operation) to the 
bedrock (Figure 5-3). Gantry rails, needed to transport the waste packages and drip shields into 
the tunnel, will be placed along the margins of the support beam structure. Guide beams will be 
used (if considered necessary to mitigate movement resulting from seismic events) to secure the 
waste package emplacement pallets and the drip shield assembly. The current design calls for 
the invert support and guide beams to be manufactured of ASTM A 572/A 572M steel, which 
was chosen to provide sufficient strength for the emplacement drift environment. The gantry rail 
will be made of ASTM A 759 carbon steel (DOE 2001 [153849], Section 2.4.1.1). 
The invert ballast is designed so that moisture present in the emplacement drift will drain directly 
into the surrounding rock without flowing along the base of the drift. Crushed tuff, produced by 
crushing material obtained during the excavation of the emplacement drifts, would be used as the 
primary ballast material. The ballast will be placed around the steel invert beams, to a level just 
below the top of the support beams, so that the waste package pallets and drip shields rest on the 
support beams and not on the ballast. The ballast material will be compacted so that no 
significant settling will occur over time. The crushed tuff should not be affected by heating 
related to emplacement of the waste packages. Transport of radionuclides within the crushed 
tuff is expected to be dominated by diffusive transport, thus serving to retard any potential 
release of radionuclides into the surrounding host rocks (DOE 2001 [153849], Section 2.4.1.2). 
5.2.3 Waste Package 
The waste package assembly is designed to securely contain high-level radioactive wastes and 
serve as the primary element to the EBS. The waste package system consists of two main 
components: a waste package emplacement pallet and a sealed, corrosion-resistant waste 
package canister (Figure 5-4). 
The waste package emplacement pallets are designed to support the waste package canisters in a 
horizontal position and facilitate line-loading of the waste packages. Current plans call for the 
pallets to be manufactured from plates of Alloy 22 (a material highly resistant to corrosion) with 
support tubes fabricated from Stainless Steel Type 316L (DOE 2001 [153849], Section 2.4.3.1). 
The V-shaped design will allow the pallets to be used for all waste package canisters. 
A number of distinct waste package designs have been developed to accommodate the different 
waste forms generated from boiling water and pressurized water reactors, excess weapons 
material, high-level waste, and DOE and naval spent nuclear fuel (Figure 5-5). All of these waste 
package designs contain a number of important components that are needed to meet performance 
criteria. The performance criteria (DOE 2001 [153849], Section 3.4.1) are as follows: 
Strength 
Resistance to corrosion and microbial attack 
Predictable materials behavior 
Compatibility with waste package and waste form materials 
Ease of fabrication 
Proven performance record 
Favorable heat transfer properties 

Utility in shielding and preventing criticality. 
Table 5-1 lists the major waste package components for commercial spent nuclear fuel waste 
packages, the composition of each component, and the component function(s). 
The different materials chosen for the construction of the waste package system are based on the 
functional requirements for each component. Key properties include resistance to corrosion and 
cracking caused by thermal, mechanical, and chemical processes; preservation of the structural 
integrity of the waste package system; conduction of heat away from the waste forms; and the 
ability to prevent criticality from occurring. A brief description of each of the main types of 
materials incorporated in the current design (DOE 2001 [153849], Section 3) is given below. 
5.2.3.1 Corrosion-Resistant and Structural Materials 
Alloy 22 was selected for the outer barrier of the waste package because of its resistance to 
corrosion under conditions of high temperatures and low humidity and under all low-temperature 
conditions, its similar thermal expansion coefficient to stainless steel, and because it can be 
welded more easily than can titanium. The chemical composition of Alloy 22 is given in Table 
5-2. Stainless Steel Type 316NG was chosen for the inner cylinder of the waste package because 
of its relative strength, compatibility with Alloy 22, and its affordability. The chemical 
composition of Stainless Steel Type 316NG is given in Table 5-3. 
5.2.3.2 Other Waste-Package Materials 
A variety of other materials will be used in the fabrication of the waste package assembly (DOE 
2001 [153849], Section 3.2.2.1). These include Neutronit A 978 (borated 316 stainless steel) or 
SA 516 Grade 70 carbon steel plates, boron carbide rods with Zircaloy cladding used for control 
of criticality within the waste package container, and aluminum shunts (SB-209 6061 T4) to 
assist in heat transport away from the waste form. The waste package will encompass the waste 
form materials described in Section 5.2.4. 
5.2.4 Waste-Form Components 
The waste forms designated for disposal at the Yucca Mountain repository include spent fuel 
from commercial power reactors and that owned by the U.S. Department of Energy, solidified 
high-level radioactive waste, and plutonium waste from excess nuclear weapons. All waste must 
be in solid form and must not contain flammable or chemically reactive materials. The waste 
forms will contain fuel rods constructed out of Zircaloy and stainless steel as well as a variety of 
radioactive waste types, including uranium metal, uranium oxide, uranium dioxide, radioactive 
borosilicate glass, and plutonium encased in ceramic pellets (DOE 2001 [153849], Section 3). 
Analogues to waste form materials and their degradation are discussed in Section 4. 
5.2.5 Emplacement Drifts 
While the emplacement drifts are not considered a component of the engineered barrier system, 
the materials used in their construction could significantly affect the EBS performance. The 
emplacement drifts contain a variety of materials that are used to help maintain the integrity of 
the drift after excavation. The ground support system, designed to stabilize the emplacement 

drift, includes W6X20 rolled steel ring beams (steel sets), tie rods, welded wire fabric, rock bolts, 
and cementitious grout used to secure the rock bolts in place (DOE 2001 [153849], Section 
2.3.4.1.2.1). Analogues relevant to emplacement drift components are discussed in Section 7. 
5.3 PROCESSES AFFECTING EBS PERFORMANCE 
Numerous processes and event scenarios have been identified and considered in designing the 
EBS (DOE 2001 [153849], Sections 2.4 and 3.1). These can be grouped into four major 
categories: structural, thermal, chemical, and nuclear criticality. The structural events evaluated 
involve scenarios (such as mishandling of the packages, seismic events, or rock falls) that would 
result in the waste package being physically disturbed by an impact that could potentially result 
in breaching the sealed waste packages. Thermal processes include changes in physical and 
chemical properties associated with heating caused by radioactive decay of the waste forms, such 
as thermal expansion and cracking, as well as the effects of heat transfer properties. Chemical 
processes such as corrosion and chemical reaction of the different materials could also result in 
breaching of the sealed waste packages and subsequent release of radionuclides into the 
surrounding environment. Special attention has been placed on the design of the waste packages 
and composition of the waste forms to prevent the radioactive waste from achieving criticality. 
The selection of the different materials used in construction of the EBS components has been 
made to ensure the long-term structural, thermal, and chemical integrity of the waste packages 
and to prevent the waste forms from going critical. 
While the properties of all of the materials selected for the EBS design have been extensively 
tested and determined in the laboratory, the long-term performance of these materials under the 
predicted temperature, humidity and chemical environment for the Yucca Mountain repository 
has not been experimentally confirmed. Natural analogues for similar materials found in the 
natural environment can be used to validate long-term performance models for the EBS. The 
following sections (6 and 7) provide descriptions of natural analogues for waste package 
materials and for processes that might take place within the EBS. 

Table 5-1. Commercial Spent-Nuclear-Fuel Waste Package 
Component 
Composition 
Function 
Outer barrier and lids 
Alloy 22 
Protect against corrosion 
Support ring 
Alloy 22 
Hold inner cylinder in place 
Inner structural shell and lid 
Stainless Steel Type 316NG 
Provide structural integrity 
Waste package fill gas 
Helium 
Heat conductor, with need to be 
compatible with spent fuel 
Fuel tubes for internal basket 
Carbon steel (SA 516 Grade 70) 
Hold fuel assemblies in place and 
provide structural strength and 
conduct heat away from cladding 
Interlocking plates for internal 
basket 
Carbon steel (SA 516 Grade 70) 
Provide structural strength to 
maintain fuel geometry and 
prevent criticality 
Neutron absorber materials for 
internal basket 
Neutronic A 978 (borated 316 
stainless steel) 
Prevent criticality, provides 
structural strength and conduct 
heat away from waste form to 
walls of waste package 
Thermal shunts for internal 
basket 
Aluminum alloy (SB-209 6061 T4) 
Transfer heat from waste form to 
walls of waste package 
Structural guides for internal 
basket 
Carbon steel (SA 516 Grade 70) 
Provide structural strength to hold 
basket structure in place and 
prevent criticality, conduct heat to 
walls of waste package 
Control rods 
Boron carbide with Zircaloy 
cladding 
Provide long-term criticality 
control 
Source: DOE 2001 [153849], modified from Table 3-9, Sections 3.1 and 3.2.2. 
Table 5-2. Chemical Composition of Alloy 22 
Element 
Composition (wt %) 
Nickel 
50 to 63 
Chromium 
20.0 to 22.5 
Molybdenum 
12.5 to 14.5 
Iron 
2.0 to 6.0 
Tungsten 
2.5 to 3.5 
Cobalt 
2.50 (max) 
Manganese 
0.50 (max) 
Vanadium 
0.35 (max) 
Silicon 
0.08 (max) 
Phosphorus 
0.02 (max) 
Sulfur 
0.02 (max) 
Carbon 
0.015 (max) 
Source: DOE 2001 [153849], modified from Table 3-12. 

Table 5-3. Chemical Composition of Stainless Steel Type 316NG 
Element 
Composition (wt %) 
Iron 
61 to 71 
Chromium 
16.00 to 18.00 
Nickel 
11.00 to 14.00 
Molybdenum 
2.00 to 3.00 
Manganese 
2.00 (max) 
Silicon 
0.75 (max) 
Copper 
0.50 (max) 
Cobalt 
0.10 (max) 
Vanadium 
0.1 (max) 
Nitrogen 
0.06 to 0.10 
Titanium 
0.05 (max) 
Tantalum and Niobium 
0.05 (max) 
Aluminum 
0.04 (max) 
Phosphorus 
0.030 (max) 
Carbon 
0.020 (max) 
Bismuth + Tin + Arsenic + Lead + 
Antimony + Selenium 
0.02 (max) 
Sulfur 
0.005 (max) 
Boron 
0.002 (max) 
Source: DOE 2001 [153849], modified from Table 3-13. 

Source: DOE 2001 ([153849], Figure 2-71). 
Figure 5-1. Cross Section of Emplacement Drift with EBS Components 

Source: DOE 2001 ([153849], Figure 2-73). 
Figure 5-2. Schematic View of Drip Shield Assembly with Drip Shield, Support Members, and Feet 
Source: DOE 2001 ([153849], Figure 2-72). 
Figure 5-3. Perspective View of Steel Invert Structure in Emplacement Drift 

Source: DOE 2001 ([153849], modified from Figure 3-1). 
Figure 5-4. Cross Section of Waste Package, Emplacement Pallet, and Drip Shield 
NOTE: PWR = Pressurized Water Reactor; DHLW = Defense High-Level Radioactive Waste; BWR = Boiling 
Water Reactor; and SNF = Spent Nuclear Fuel. Source: DOE 2001 ([153849], Figure 2-77). 
Figure 5-5. Schematic View of Different Waste Packages in Emplacement Drift 

6. WASTE-PACKAGE DEGRADATION ANALOGUES 
6.1 INTRODUCTION 
This section describes the use of natural analogues to evaluate the long-term performance of 
metals used in the fabrication of waste packages for storage of high-level radioactive waste. Key 
concerns for the waste package materials (described in Section 5) include the possible 
degradation and corrosion of metals caused by mechanical stress, aggressive physical and 
chemical environments, and metallurgical factors. The primary degradation and corrosion issues 
expected for Yucca Mountain include elevated temperature and humidity, and contact with 
seepage water that could have corrosive chemistry. A number of different analogues were 
previously discussed in Chapter 13 of the Yucca Mountain Site Description (CRWMS M&O 
2000 [151945], Section 13.3.5); those analogues applicable to the waste materials described in 
Section 5 are briefly summarized below. Additional analogue examples are discussed in more 
detail in the following subsections. 
The long-term stability of the waste package materials is directly related to repository 
environmental conditions. Preservation of delicate archaeological materials, including metals, 
appears to be enhanced by their location in an arid or semi-arid unsaturated environment 
(CRWMS M&O 2000 [151945], Section 13.3.4). Mummified remains 4,000 to 8,000 years in 
age were discovered in shallow burial pits in the high Andes Mountains of Chile. The Dead Sea 
scrolls were preserved in caves along the shores of the Dead Sea for over 2,000 years. All of 
these artifacts have survived millennia, and their preservation is attributed in part to being in arid 
to semiarid unsaturated environments (Winograd 1986 [127015], p. 8). 
Metal analogues, involving both naturally occurring and archaeological objects, were also 
described in the Yucca Mountain Site Description (CRWMS M&O 2000 [151945], Section 
13.3.5). A cache of Roman iron nails was recovered after almost 1,900 years of burial in 
Scotland (Miller et al. 1994 [126089], pp. 114119). Corrosion of the outermost nails formed a 
protective rust rind, serving to create a more reducing (and thus more stable) environment for the 
innermost nails. Using a variety of iron archaeological artifacts, Johnson and Francis (1980 
[125291], Figure 3-1) calculated general corrosion rates of 0.1 to 10 m/yr for most of the 
artifacts under a range of environmental conditions. Iron meteorites often have poorly 
constrained exposure histories, but differential corrosion of different mineral phases can be used 
to estimate relative resistance to corrosion, suggesting that Ni-rich phases (taenite and 
schreibersite) are more stable than Fe-rich phases (Johnson and Francis 1980 [125291], p. 4.23). 
Copper-bearing archaeological artifacts, such as sunken and buried bronze cannons, can also be 
used to estimate general corrosion rates over extended (hundreds to thousands of years) periods 
of time. These metal analogues, while differing in chemical composition from the waste package 
films, provide important insights into the way different metals survive corrosion over long time 
periods, and illustrate the importance of passive films. 
Most of the metals being considered for use in the waste packages at the Yucca Mountain 
repository consist of alloys that do not occur naturally and are not present in the archaeological 
record (see Tables 5-1 to 5-3). However, the long-term behavior of metals with similar 
compositions that are present either as minerals or as man-made objects can be used to build 

confidence in long-term performance models of the waste package materials. Analogues to longterm 
behavior of metals related to waste package materials are described in Section 6.2.3. 
Information found in Section 6.2 may help to support arguments associated with Key Technical 
Issue (KTI) KUZ0407 listed in Table 1-1. 
6.2 NATURAL ANALOGUE STUDIES OF CORROSION 
This section discusses new work on some of the natural analogues previously summarized in 
Chapter 13 of the Yucca Mountain Site Description (CRWMS M&O 2000 [151945]), as well as 
information on examples not previously discussed in the Site Description. 
6.2.1 Environmental Factors Related to Corrosion 
Knowledge of the in-drift physical and chemical environment at Yucca Mountain is critical in 
predicting the long-term performance of waste packages and the EBS. Processes such as the 
evaporation and condensation of water, precipitation and dissolution of salts, seepage and mass 
transport of materials into the drift environment, and the abundance, compositions, and reactions 
between solid, liquid, and gas phases will affect the physical and chemical integrity of waste 
packages and other EBS components. 
One of the key attributes of the Yucca Mountain repository is its location within the unsaturated 
zone (UZ), thus reducing the amount of water that can come into contact with waste packages. 
Previous reviews of natural analogues of caves within the UZ have demonstrated that very old 
archaeological artifacts can be preserved in such environments (CRWMS M&O 2000 [151945], 
Section 13.3.4). Hundreds of wooden and reed fragments of dart and arrow shafts (dated 
between 3,300 to 9,300 years B.P.) have been recovered from Pintwater Cave in southern 
Nevada (Buck and DuBarton 1994 [157438], pp. 228, 239). These delicate items were collected 
from the limestone cave floor and in a test pit excavated within eolian sediments lining the floor 
of Pintwater Cave (Buck and DuBarton 1994 [157438], p. 226), and their preservation suggests 
that they were not subjected to prolonged exposure to water. However, as shown in the 
following example, the maintenance of a stable microclimate is a critical feature in making caves 
suitable for long-term preservation. 
The Altamira cave, located in northern Spain, is the site of Paleolithic cave paintings (Sanchez- 
Moral et al. 1999 [157382]). Since the discovery of the prehistoric cave art in 1879, significant 
degradation of the cave paintings has occurred, leading to the cave being closed to the public in 
1977. The cave was reopened in 1982 with fixed limits on the number of visitors. Continuous 
monitoring of the Altamira cave microclimate within Polychromes Hall (a cave chamber with 
famous polychromatic paintings) during 19971998 determined that increases in temperature (. 
= +0.25C) and CO2 concentrations (. = +500 ppmv) resulted directly from the presence of 
visitors in the cave (Sanchez-Moral et al. 1999 [157382], p. 78). 
Sanchez-Moral et al. (1999 [157382]) used these data to estimate effective calcite corrosion rates 
for both the baseline and modified (visitor-related case) cave conditions. They predicted that the 
visitor-induced temperature increase (resulting from radiation of body heat) will greatly increase 
the amount of water condensation occurring on the cave walls and ceiling. The elevated PCO2 
(partial pressure of carbon dioxide) conditions caused by human respiration, combined with the 

higher amounts of condensation, were predicted to result in visitor-induced corrosion rates (314 
mm3/yr) in Polychromes Hall that are 78 times higher than the baseline (no visitor) case 
(Sanchez-Moral et al. 1999 [157382], p. 78). As noted by visual observation and modeling, the 
relatively minor changes in temperature and PCO2 at Altamira had a significant impact on 
deterioration of the cave art. Thus, the corrosion-resistance properties of waste package 
materials at Yucca Mountain need to be evaluated for all possible variations in environmental 
conditions during the postclosure period. 
One critical factor affecting the chemical integrity of the waste packages is the potential 
development of hypersaline fluids within emplacement drifts at Yucca Mountain. Such fluids 
could be generated by evaporative concentration of dissolved salts in pore waters in the near-drift 
environment caused by heating, or by dissolution of previously formed salts in the dryout zone 
around the drift by downward percolating condensate waters and/or surface infiltration. The 
amount and salinity of water in contact with waste packages depend on a number of factors, 
including evaporation, condensation, temperature, and fluid flux rates into the emplacement 
drifts (Figure 6-1). Conceptual and numerical models of these processes suggest that fluid 
compositions within the emplacement drifts may be highly variable over time (Walton 1994 
[127454], pp. 34833486). 
To constrain models involving the generation of hypersaline fluids at Yucca Mountain, 
Rosenberg et al. (2001 [154862]) conducted a series of experiments at sub-boiling temperatures 
(7585C) to evaluate the evaporative chemical evolution of pore water from the UZ and of well 
water from the saturated zone (SZ) at Yucca Mountain. Synthetic solutions of these two fluid 
types were evaporated, with samples collected and analyzed after approximately 100 and 1,000  
evaporative concentration and evaporation to dryness (Table 6-1). A number of different 
minerals formed from complete evaporation of these waters, including amorphous silica, 
aragonite, calcite, halite, niter, smectite, thermonatrite, tachyhydrite, and gypsum. The 
groundwater (obtained from the J-13 well at Yucca Mountain) composition evolved into a high 
pH, sodium carbonate-bicarbonate brine resulting from the precipitation of calcium-magnesium 
carbonate, while the UZ pore-water composition evolved into a near-neutral pH, sodiumpotassium-
calcium-magnesium-chloride-nitrate brine resulting from the precipitation of gypsum. 
Different fluid chemistry may develop under higher temperature (boiling) conditions as a result 
of CO2 degassing, which could have an important impact on the pH of the evolved fluids. These 
experimental results provide a data set against which to compare brines from analogue sites that 
have interacted with metals in a natural environment. 
Hypersaline fluids, such as those encountered at the Salton Sea geothermal field (Table 6-2), 
have been observed to corrode many steel compositions aggressively (McCright et al. 1980 
[157384], pp. 646648). Carbon steel drill casings initially used in geothermal production wells 
at the Salton Sea field experienced general corrosion rates as high as 25.4 mm/yr, with even 
higher localized corrosion rates observed (Pye et al. 1989 [157385], p. 260). These rates are 
much higher than the rates of 1040 m/yr obtained by Ahn and Soo (1995 [104751], p. 475) for 
corrosion tests of A216-Grade WCA low-carbon steel in concentrated synthetic groundwater 
solutions. The differences in corrosion rates likely result from: (1) differences in steel 
compositions; (2) higher temperatures for the Salton Sea fluids (232315C) than that those used 
for the corrosion experiments (80150C); and (3) much higher salinities for the Salton Sea 
brines (150,000300,000 ppm total dissolved solids (TDS)) relative to the synthetic experimental 

brines (7,455 ppm TDS). Corrosion problems at the Salton Sea were successfully mitigated 
through the use of a corrosion-resistant titanium alloy (see Section 7.2.1). The current drip 
shield design for Yucca Mountain (see Section 5.2.1) calls for the use of titanium because of its 
corrosion-resistant properties. 
Another concern for waste package materials is the possible evaporative concentration of minor 
dissolved constituents, such as arsenic, lead, and mercury, that could enhance corrosion (BSC 
2001 [155950], Section 7.3.1.3.4; [157151], Appendix E, Section 3.1.2). The hypersaline Salton 
Sea brines have significant concentrations of arsenic (8 ppm) and lead (66 ppm). However, 
groundwaters in the vicinity of Yucca Mountain have only trace amounts of lead, with a median 
concentration of 9 ppb (Lee 2001 [155241]; Perfect et al. 1995 [101053]). Two samples of J-13 
well water from Yucca Mountain were analyzed for lead, with one sample yielding a value of 3 
ppb, while the other was below detection (BSC 2001 [155950], Section 7.3.1.3.4; Perfect et al. 
1995 [101053]). Lead concentrations in groundwater at Yucca Mountain may be limited by 
precipitation of lead in the form of carbonate, oxide, or sulfide minerals, or by sorption onto 
mineral surfaces (BSC 2001 [155950], Section 7.3.1.3.4, [157151], Appendix E, Section 3.1.2). 
Evaporative concentration of water in the near-drift environment at Yucca Mountain could result 
in higher lead concentrations. However, even a 1,000-fold increase in lead concentration in J-13 
water would still only result in a brine with ~3 ppm lead, over 20 times lower than the 
concentrations observed in Salton Sea brines. Thus, the very low concentrations of lead in 
groundwater at Yucca Mountain greatly reduce the risk that lead (and other trace metals) could 
pose to the chemical integrity of the waste packages. 
6.2.2 Passive Film Formation 
The formation of passive films has a significant impact on the corrosion-resistant properties of 
metals and metal alloys (BSC 2001 [155950], Section 7.3.4). Passive films are stratified 
coatings consisting of an inner oxide layer and an outer layer of hydroxide or oxyhydroxide 
(Macdonald 1992 [154720], pp. 34343437; Marcus and Maurice 2000 [154738], pp. 145152]. 
The inner layer forms a corrosion barrier, while exchange occurs within the outer layer of the 
passive film. These films act as semiconductors or insulators, thus reducing the rate of metal 
dissolution triggered by an electrochemical potential between a metal and its surrounding 
electrolyte solution. 
The Delhi iron pillar is a 1,600-year old metal artifact (Figure 6-2) that has withstood exposure 
to the atmosphere with only relatively small amounts of corrosion. Study of the rust layer 
coating the pillar reveals the presence of crystalline iron hydrogen phosphate hydrate and 
amorphous iron oxyhydroxides and magnetite (Balasubramaniam 2000 [157383], pp. 2115 
2116). The low-porosity crystalline phosphate phase forms a passive film around the pillar, 
serving to protect it from further corrosion (Figure 6-3). Balasubramaniam (2000 [157383], pp. 
21122115) interpreted the presence of ~0.25 wt% phosphorous and fine slag particles in the 
iron to be critical to the development of the corrosion-resistant layer. 
6.2.3 Naturally Occurring Metals as Natural Analogues 
JosephiniteJosephinite, a naturally occurring Ni-Fe-Co metal-bearing rock consisting of the 
minerals Ni3Fe (awaruite), andradite garnet, FeCo (wairuite), and minor to trace amounts of 

Ni6Fe4 and CaO2FeO (calciowstite), is a possible natural analogue for Ni-Fe alloys (similar to 
Alloy 22, which is a Ni-Cr-Mo-W alloy) planned for the Yucca Mountain waste packages. The 
type locality of josephinite is the Josephine Ophiolite, a ~150 million-year-old serpentinized 
ultramafic body in Oregon, where it occurs within serpentine veins and as coarse metallic 
nuggets in nearby placer deposits (Dick 1974 [154749]). Josephinite was interpreted by Dick 
(1974 [154749], p. 297) to be a product of hydrothermal alteration and serpentinization of 
peridotite. Josephinite and awaruite are very stable rock and mineral phases, as evidenced by 
their survival for millions of years with only minor amounts of oxidation. Because of this longlived 
stability, these ordered Ni-Fe-Co metals (Bassett et al. 1980 [157531]) have been proposed 
as alloys in constructing containers for the storage of high-level radioactive waste (Bird and 
Ringwood 1980 [157397]; 1982 [157398]; 1984 [157396]). 
Relatively unaltered masses of metal that are predominantly Ni3Fe (with small inclusions of 
Ni3As) were discovered in 1999 within harzburgite in the Josephine Ophiolite and as eroded 
blocks weighing up to ~3 kg (Bird 2001 [157514]). Preliminary Pb and Os isotopic analyses of 
these new samples suggest that the josephinite metal did not form as an alteration product of the 
Josephine Ophiolite but, instead, may represent xenoliths within the serpentinite body that have a 
deep-mantle origin (Bird 2001 [157514]). 
The josephinite nuggets have alteration rims comprised of Fe3O4 (magnetite, with maghemite) 
and NiFe2O4 (trevorite). Some samples of josephinite contain the high-temperature phase taenite 
(a disordered Ni-Fe metal) in addition to awaruite (BSC 2001 [155950], Section 7.3.2.4.2). 
Phase relation studies of the Fe-Ni system suggest that taenite is not stable below ~350C, and 
that a-Fe, pure Ni, and awaruite are the stable phases for this system at ambient temperatures 
(Botto and Morrison 1976 [154716], p. 264). The persistence of taenite for millions of years 
suggests that low-temperature phase change rates for taenite are exceedingly slow (BSC 2001 
[155950], Section 7.3.2.4.2). X-ray photoelectron spectroscopic analysis of a josephinite placer 
sample from the Josephine Ophiolite (Figure 6-4) revealed that while both iron and nickel are 
oxidized on the surface, nickel remains in reduced (metallic) form at depths of 2 nm and greater 
(analyzed to a depth of 120 nm), indicating that the bulk sample has not undergone significant 
amounts of oxidation (BSC 2001 [157151], Appendix E, Section 3.3.2, Table 1). Because of its 
high nickel concentrations, the longevity of josephinite indicates that nickel alloys will have 
long-term phase stability. While josephinite does not contain the molybdenum and tungsten that 
serve as stabilizing elements in Alloy 22 passive films, its ability to resist corrosion provides 
confidence that Alloy 22 will remain passive under repository conditions (BSC 2001 [157151], 
Section 3.3.2, Appendix E). 
ChromiteAnalogues for chromium are considered because of the chromium content of Alloy 
22 (Table 5-2). Chromium occurs in minerals in the form of chromite (FeCr2O4) and chromium 
spinel (Mg(Cr,Al)2O4). These Cr-bearing minerals are typically found in mafic and ultramafic 
rocks. Elevated concentrations of chromium in groundwaters in the Leon-Guanajuato valley of 
central Mexico have been attributed to weathering and alteration of chromite from ultramafic 
rocks of the Sierra de Guanajuato that have been interpreted to be Jurassic in age (Robles- 
Camacho and Armienta 2000 [157386], pp. 172173, 178181). The San Juan de Otates 
pyroxenite unit consists of pyroxenite and serpentinized peridotite, harzburgite, and wehrlite. 
Discrete concentrations of ilmenite and chromite occur within these rocks, and form subrounded 

masses in outcrop. Chromite is typically found as subrounded crystals, often with exsolution 
borders of magnetite. 
A variety of ultramafic rock samples from the Sierra de Guanajuato, with total chromium 
contents ranging from 55 to 4115 ppm, were leached with acid to evaluate the susceptibility of 
the rocks to weathering and subsequent release of chromium (Robles-Camacho and Armienta 
2000 [157386], pp. 173181). The laboratory acid treatment was designed to examine (over a 
much shorter time scale and under much more acidic conditions that found in the field) the 
effects of weathering resulting from interaction of oxygenated, CO2-rich groundwater with 
chromium-bearing minerals (Robles-Camacho and Armienta 2000 [157386], pp. 174177). The 
leachate from Cr-rich serpentinite samples yielded the highest concentrations (up to 274 mg 
Cr/kg rock), suggesting that they have the greatest potential to release chromium. SEM analysis 
of samples examined after leaching suggests that dissolution occurred along magnetite 
exsolution borders of chromite grains (Figure 6-5). Total chromium contents of groundwater 
samples collected from wells, streams, and reservoirs near the ultramafic rocks range up to 
0.0149 mg/L. Concentrations at this level may be analogous to the very long-term chromium 
concentrations that may be expected to leave the engineered barrier system at Yucca Mountain; 
the Environmental Impact Assessment estimated a value of 0.015 mg/L for chromium (DOE 
2002 [155970], Appendix I, Table I-31). The Ca-Mg-HCO3 composition of these waters is 
consistent with interaction with serpentinized ultramafic rocks. The study does not provide 
information on the rates of chromite weathering, but it does indicate that chromite exsolution 
borders are susceptible to chemical attack. This observation is analogous to localized corrosion 
and pitting observed in metals along structural defects. 
6.3 SUMMARY 
The survival of metal archaeological artifacts over prolonged periods of time is related 
to the corrosion-resistant properties of metals and metal alloys, the development of 
protective passive film coatings with the onset of corrosion, and the location of artifacts 
in arid- to semi-arid environments. Such features can be used in the selection of 
materials and design configuration to enhance the durability of waste packages at 
Yucca Mountain. 
Archaeological examples, such as the Altamira cave, illustrate how environmental 
changes can significantly affect corrosion behavior. A wide variety of environmental 
conditions is expected to occur in the near-drift environment at Yucca Mountain during 
the lifespan of the repository. The introduction of heat-generating waste packages and 
EBS materials into drifts will perturb the existing physical and chemical system at 
Yucca Mountain. The materials used for the waste packages (and the rest of the EBS) 
need to withstand the predicted adverse changes in environmental conditions. 
Small volumes of concentrated brines could develop in the near-drift environment as a 
result of evaporation and later dissolution of precipitated salts in the dryout zone with 
rewetting. High-salinity fluids pose a significant corrosion hazard to carbon steel, as 
seen at the Salton Sea geothermal field, but the use of titanium alloys can effectively 
minimize this hazard. 

The survival for millions of years of the naturally occurring ordered Ni-Fe alloy found 
in josephinite (with only relatively minor amounts of surface oxidation) indicates that 
this material is highly resistant to oxidation and other forms of corrosion that occur in 
its geologic environment. While the composition of this metal differs from Alloy 22 
(in that it does not contain Cr, Mo, and W), it does provide evidence that a similar alloy 
can remain passive over prolonged periods of time. 
The potential instability of chromium-bearing materials is illustrated by the observed 
natural release (under ambient conditions) of chromium from chromite in the Sierra de 
Guanajuato ultramafic rocks. Corrosion appears to be concentrated along exsolution 
rims, analagous to structural defects on metal surfaces. While the chromite has 
undergone some alteration, it has survived for over 140 m.y. (since Jurassic time). The 
corrosion behavior of this chromium oxide mineral may differ from that of the 
chromium-bearing metal alloys (Section 5) that are currently slated for use in the 
construction of the waste package. 

Table 6-1. Composition of Synthetic Yucca Mountain Waters (mg/L) from Unsaturated and Saturated 
Zones and Their Evaporated Compositions 
Synthetic 
J-13 water 
157 ה 
J-13 water 
956 ה 
J-13 water 
Synthetic 
UZ water 
62 ה 
UZ water 
1243 ה 
UZ water 
Na 
45.2 
5,288 
43,302 
8.56 
477 
6,223 
K 
5.2 
593 
4,701 
4.00 
268 
2,644 
Mg 
2.1 
1.2 
0.13 
11.8 
550 
5,546 
Ca 
5.8 
0.06 
27.3 
57.3 
1,713 
15,643 
SiO2 
10.4 
1,040 
---- 
10.4 
503 
541 
HCO3 
105 
4,410 
24,255 
20.3 
9.9 
<45 
SO4 
18.5 
2,109 
13,209 
83.9 
1,544 
2,098 
Cl 
7.2 
814 
5,047 
76.6 
4,259 
52,165 
NO3 
7.9 
1,035 
5,483 
10.7 
592 
---- 
F 
2.3 
237 
1,622 
2.16 
38 
<542 
TDS 
209.6 
15,527 
97,646 
285.7 
9,954 
~85,000 
pH 
8.07 
10.18 
---- 
7.55 
7.65 
66.5 
NOTE: TDS calculated as sum of dissolved solids. 
Source: Rosenberg et al. 2001 [154862], Tables 2 and 4. 
Table 6-2. Typical Salton Sea Geothermal Well Brine Composition 
Component 
Concentration 
ppm 
Component 
Concentration 
ppm 
Na 
49,800 
Ba 
100 
K 
12,840 
B 
301 
Mg 
80 
Cu 
7 
Ca 
24,000 
Fe 
708 
SiO2 
658 
Pb 
66 
CO2 
125 
Li 
177 
SO4 
22 
Mn 
785 
Cl 
126,700 
Rb 
62 
NH3 
339 
Sn 
402 
As 
8 
Zn 
287 
I 
5 
Br 
68 
pH 
5.8 
H2S 
90 
TDS 
261,800 
Source: Pye et al. 1989 [157385], Table 1. 

Source: Walton 1994 [127454], Figure 3. 
Figure 6-1. Processes Affecting Formation of High-Salinity Fluids on Waste Package Surface 
Source: Balasubramaniam 2000 [157383], Figure 1. 
Figure 6-2. The Corrosion-Resistant Iron Pillar at Delhi 

NOTE: Iron hydrogen phosphate hydrate layer on Delhi iron pillar forms a 
protective, impermeable coating that retards further corrosion. 
Source: Balasubramaniam 2000 [157383], Figure 7. 
Figure 6-3. Schematic Showing Development of Rust Coating 
on Mild Steel, Weathering Steel, and Delhi Iron Pillar 
NOTE: Metallic-looking areas were analyzed 
using X-ray photoelectron spectroscopy. 
Source: BSC 2001 [157151], Appendix E, Figure 3. 
Figure 6-4. Josephinite Sample Used for Surface Analysis Study 

NOTE: White rim around chromite in (b) reflects dissolution of exsolution border around chromite. 
Source: Robles-Camacho and Armienta 2000 [157386], Figures 5 and 8. 
Figure 6-5. Chromite Grains in Serpentinite Before (a) and After (b) Acid Leaching 

7. ENGINEERED BARRIER SYSTEM ANALOGUES 
7.1 INTRODUCTION 
This section describes the use of natural analogues to evaluate the long-term performance of 
materials used in the construction of the Engineered Barrier System (EBS) and how these 
materials may affect radionuclide transport. The primary functions of the EBS components are 
to: (1) protect the waste package from physical and chemical degradation resulting from 
processes such as seepage, corrosive fluids, and rock fall; and (2) retard any potential transport 
of radionuclides from the emplacement drift in the event of waste package failure. Key concerns 
for the EBS materials (described in Section 5) include the possible degradation and corrosion of 
metals resulting from mechanical stress, aggressive physical and chemical environments, and 
metallurgical factors. Another important performance parameter is the effect of EBS materials 
on flow and transport of fluids and dissolved solids into and out of the emplacement drifts. 
Important issues relating to EBS performance include the degradation of materials caused by 
corrosive fluids, radiation, thermal and physical stresses, and microbial attack, as well as the 
effects of sorption and colloids on radionuclide transport. A number of analogues relating to 
EBS processes were previously discussed in Section 13 of the Yucca Mountain Site Description 
(CRWMS M&O 2000 [151945]); these analogues are briefly summarized below. Additional 
analogue examples are discussed in more detail in the following subsections. 
Three main issues relating to the EBS were discussed in detail in the natural analogues chapter of 
the Yucca Mountain Site Description (CRWMS M&O 2000 [151945], Section 13.3): (1) metal 
analogues (native metals and archaeological artifacts) in the evaluation of corrosion resistance; 
(2) cements and alkaline plumes to determine the impact of high pH fluids on EBS materials, 
surrounding host rock, and radionuclide transport; and (3) the effects of radiolysis on the 
integrity of waste package materials. A brief summary of earlier work on metal analogues is 
presented in Section 6 and thus will not be repeated here. 
Under the current EBS design, cementitious material is expected to be present in only minor 
amounts (as grout for rock bolts) in the near-drift environment. The durability of cements over 
time has been documented by Gallo-Roman cements that are over 1,500 years old (Thomassin 
and Rassineux 1992 [157439], p. 137). Cementitious mortar from Hadrians Wall (~1,700 years 
old) in England (Figure 7-1) has the same calcium silicate hydrate phases found in modern 
Portland cement, and still possesses excellent strength and stability (Miller et al. 2000 [156684], 
p. 131). The potential development of hyperalkaline fluids resulting from interaction of water 
with cementitious material could affect radionuclide transport and reduce the stability of EBS 
materials. Two areas with hyperalkaline fluids were described in the earlier review of natural 
analogues (CRWMS M&O 2000 [151945], Section 13.3.6): the Semail ophiolite in Oman, and 
the Maqarin area in Jordan. Serpentinization reactions in the Semail ultramafic rocks have 
resulted in the generation of reducing, hyperalkaline (pH = 1012) Na-Cl-Ca-OH fluids, with 
associated minerals brucite (Mg(OH)2) and portlandite (Ca(OH)2). The Maqarin analogue site 
(also discussed in Section 7.3.1) contains a suite of naturally formed cement minerals, including 
portlandite. High pH (1213) fluids emanate from these rocks as a result of reaction of 
groundwater with the cement phases. These analogue sites have been used in the development of 

numerical models to predict water-rock reactions and resulting fluid compositions under similar 
conditions (McKinley et al. 1988 [126077]; Chambers et al. 1998 [157549]). 
Chemical decomposition resulting from radiation (radiolysis) was also examined in the Yucca 
Mountain Site Description (CRWMS M&O 2000 [151945], Section 13.3.7). This process was 
studied at the natural reactor site at Oklo (in Gabon), where high radiation doses were interpreted 
to have led to radiolysis of water and redox reactions involving the surrounding rocks (Curtis and 
Gancarz 1983 [124785]). Similar reactions within the waste package assembly could lead to 
decomposition of the waste packages and release of radionuclides. However, since the waste 
loads are configured so that they will not approach criticality and the waste package design 
excludes free water, the amount of radiolysis that might occur at the Yucca Mountain repository 
should be much less than occurred at Oklo (see also Section 4 of this report). Section 7.2 
describes analogues for EBS materials and Section 7.3 describes analogues for EBS processes. 
7.2 ANALOGUES FOR EBS MATERIALS 
7.2.1 Analogues for the Titanium Drip Shield 
Corrosion caused by saline fluids has been identified as a potential hazard to the integrity of 
waste packages (see Section 6.2.1 for discussion). The drip shield assembly is designed to 
protect the waste packages from physical and chemical degradation resulting from events such as 
rock falls, seepage, and saline fluids. The current drip shield design calls for corrosion-resistant 
titanium. Titanium metal does not occur in nature, nor in the archaeological record, so other 
proxies are needed to assess its long-term resistance to corrosion. 
The Salton Sea geothermal field in California is characterized by hypersaline (15-30 wt% TDS) 
brines that have caused significant corrosion and scaling problems (Pye et al. 1989 [157385], 
p. 259). A series of corrosion tests led field operators to select Beta-C titanium (Ti-3Al-8V-6Cr- 
4Mo-4Zr) for the fabrication of corrosion-resistant production casing (Pye et al. 1989 [157385]). 
Four tests were conducted over a period from 256 to 833 days, involving installation of full-size 
Beta-C titanium tubulars in geothermal production wells, resulting in no visible pitting corrosion 
in two of the tests, little or no change in hydrogen content, and no significant degradation in 
mechanical properties (Pye et al. 1989 [157385], pp. 262263). In the 833-day test, localized 
corrosion was observed, occurring at a rate of 7 mils/yr (178 m/yr); this was interpreted to have 
occurred in an area where surface contamination had not been completely removed at the start of 
the test. Local corrosion was observed along 2 of the 48 casing joints in the fourth test; this 
corrosion was also interpreted to be the result of pre-existing surface contamination. 
A longer-term evaluation of the corrosion behavior of titanium-bearing materials can be obtained 
by examining the stability of naturally occurring titanium minerals. Titanium is present as a 
major constituent in a number of refractory accessory minerals commonly found as a minor 
phase in igneous rocks and in heavy mineral concentrates in sediments. These minerals include 
sphene (titanite) (CaTiSiO4(O,OH,F)), rutile (TiO2), ulvspinel (Fe2TiO4) and ilmenite (FeTiO3). 
The Canadian nuclear waste disposal concept includes a metallic titanium container surrounding 
spent fuel. The corrosion resistance of titanium arises from its passivation in aqueous solutions 
by the formation of a protective layer containing rutile (Cramer 1994 [157537], pp. 810). At the 
Cigar Lake uranium deposit in Saskatchewan, Canada, rutile is present within the uranium ore 

and has persisted unchanged for over a billion years in reducing groundwaters, under 
hydrothermal conditions, and in a radiation field. While rutile and other titanium-bearing 
minerals are oxides, and thus do not share the same physical properties as metals, their general 
resistance to alteration reflects the stable nature of titanium-bearing materials. 
7.2.2 Analogues for the Invert Ballast 
The nonwelded Calico Hills Formation and portions of the Paintbrush Tuff at Yucca Mountain 
are possible analogues for processes, such as sorption and ion exchange, which would affect the 
transport of radionuclides within the crushed tuff invert ballast. The relative lack of fractures in 
these tuffs results in fluid flow occurring in the tuff matrix, resulting in overall slower fluid flow 
and transport in these units caused by the lack of fast flow pathways, similar to what is predicted 
for the crushed tuff invert. Because of the presence of zeolites and/or smectite in the nonwelded 
tuffs, extensive ion exchange occurs between pore waters and the tuffs (Vaniman et al. 2001 
[157427]). The zeolitic tuffs are significantly enriched in cations such as Ca2+, Mg2+, and Sr2+, 
and depleted in Na+ and K+ (Figure 7-2); thus, waters are interpreted to have complementary 
(opposite) enrichments and depletions (Vaniman et al. 2001 [157427], pp. 34203423). This ionexchange 
process would have a major impact on radionuclide transport, with species such as 90Sr 
being effectively immobilized by this process. However, the current design for the invert ballast 
(DOE 2001 [153849], Section 2.4.1.2) uses crushed tuff derived from the repository interval 
(welded, devitrified Topopah Spring Tuff), which has only minor amounts of zeolites and clays 
(Vaniman et al. 2001 [157427], Figure 2). As a result, the ion exchange and sorption capacity of 
the crushed tuff invert ballast should be significantly lower than that observed in the nonwelded 
tuffs at Yucca Mountain. The crushed tuff invert would have high effective grain surface areas, 
which would favor sorption of species onto mineral surfaces, thus serving to retard radionuclide 
transport. 
The effects of fluid flow on radionuclide retardation in ash flow tuff can also be evaluated 
through an anthropogenic analogue. At Los Alamos National Laboratory, radionuclide-bearing 
liquid wastes were discharged from 1945 to 1967 into gravel and cobble-filled absorption beds 
(approximately 6 m  37 m) built on outcrops of moderately welded rhyolite ash flow tuff 
(Figure 7-3) (Nyhan et al. 1985 [157447], p. 502). Large amounts (corresponding to a depth of 
20.5 m) of tap water and radioactive effluent were added to one of the absorption beds (Bed 1) in 
1961 to evaluate radionuclide mobility. The site was revisited in 1978, when profiles of Pu and 
241Am were measured in a series of 30.5 m deep boreholes drilled through two of the absorption 
beds (Bed 1 and Bed 2) and into the underlying ash flow tuff (Nyhan et al. 1985 [157447], p. 
502). This study revealed that the bed where water and effluent had been added in 1961 (Bed 1) 
exhibited higher water saturations, along with significantly more radionuclide migration out of 
the absorption bed and into the underlying tuff (Figure 7-4), than the bed where no additional 
fluid had been added during this test (Bed 2). Plutonium and 241Am were not detected beyond 
11.28 m below the bottom of Bed 2, whereas 0.3 to 5.1% of the plutonium and 3.0 to 49% of the 
americium inventory were present within the depth interval of 11.2827.13 m for Bed 1 (Nyhan 
et al. 1985 [157447]), p. 506). Elevated concentrations of radionuclides were observed to occur 
within lower permeability intervals of the tuff. The radionuclide concentrations of fracture 
fillings were similar to those of adjacent tuff samples, suggesting that fractures did not enhance 
radionuclide transport under unsaturated conditions and generally acted as barriers to unsaturated 
zone (UZ) flow (Nyhan et al. 1985 [157447], pp. 504505, 508). These results suggest that 

radionuclide mobility was triggered by flushing of the absorption beds with large volumes of 
fluids. The volume of the column of fluid used in the Los Alamos test is equivalent to the 
amount of percolating surface water expected to flow through Yucca Mountain over a timespan 
of 2,000 to 4,000 years (assuming an infiltration rate of 5 to 10 mm/yr (Flint et al. 2001 
[156351], p. 26), and thus represents an illustration of the effects of flushing on radionuclide 
mobility. However, this example does suggest that the ability of the invert ballast at Yucca 
Mountain (as well as the underlying welded tuffs) to retard radionuclide migration will depend in 
part on the amount of water flowing through this interval. Both of the analogue examples 
described are also relevant to processes controlling radionuclide transport in the UZ at Yucca 
Mountain (see Section 10). 
7.3 NATURAL ANALOGUES FOR EBS PROCESSES 
The physical and chemical conditions for the near-field area around the emplacement drifts at 
Yucca Mountain are predicted to undergo changes over time. These changes would result from 
coupled thermal-hydrologic-chemical (THC) processes, such as boiling, condensation, fluid flow 
and transport, and mineral dissolution, alteration, and precipitation (BSC 2001 [154677]). THC 
processes are also expected to occur within the EBS, and could lead to degradation of the EBS 
components, resulting in the release and transport of radionuclides away from the EBS. Natural 
analogue studies for some of the processes expected to impact the EBS system, such as the 
generation of alkaline plumes resulting from interaction of water with cementitious material and 
the effects of colloids on radionuclide transport, are described below. 
7.3.1 Natural Analogues for Development of Alkaline Plumes from Cement 
The presence of naturally occurring cement minerals and associated hyperalkaline groundwaters 
at Maqarin, Jordan, has been used as a natural analogue for examining the effects of 
hyperalkaline waters (e.g., Khoury et al. 1992 [125677]; Smellie 1998 [126633]). The Maqarin 
site consists of interbedded bituminous limestones and marls that have been locally thermally 
metamorphosed from spontaneous combustion of the bitumen, resulting in the calcination of 
limestone and formation of cement minerals, including portlandite. Water interacting with 
portlandite has resulted in the formation of highly alkaline (pH  12.5) groundwaters and the 
precipitation of minerals such as ettringite and thaumasite at ambient temperatures (Figure 7-5). 
Initial geochemical modeling efforts resulted in model predictions of dissolved selenium and 
uranium concentrations that were several orders of magnitude higher than those observed in the 
field (Linklater et al. 1996 [108896], p. 67). A multicomponent reactive transport model that 
incorporated mixed equilibrium and kinetic reactions was applied to simulate rock alteration 
mineralogy and fluid chemistry changes for discrete fractures in the Maqarin system (Steefel and 
Lichtner 1998 [156714]). These simulations predict the formation of hydrated calcium sulfate 
and silicate minerals, such as ettringite and tobermorite, which were observed in the field 
(Khoury et al. 1992 [125677], p. 122), and also reproduced measured fluid pH values. The 
simulations suggest that mineralization caused by interaction of the hyperalkaline plume with 
surrounding rocks may result in both reduction of matrix porosity and fracture sealing. Fractures 
at the Maqarin site have complex mineralogy and textures that suggest that they have undergone 
repeated sealing and reopening over time. The relative rates of matrix and fracture mineralization 
(and associated reduction in permeability) will significantly affect the mobility of the alkaline 
plume, and thus the transport of associated radionuclides. 

The development of large hyperalkaline plumes and associated alteration and transport are not 
expected to occur at Yucca Mountain. The amount of cementitious material expected to be 
present in the repository (in the form of grout around rock bolts in the emplacement drifts) is 
much less than what is observed at Maqarin. The fluid pH of the near-field environment thus will 
be buffered by tuff rather than by portlandite, resulting in less alkaline pH conditions (DOE 2001 
[153849], Section 4.2.3.3.3). The Maqarin natural analogue is important to consider in 
illustrating the effects of alkaline fluids on water-rock processes, and thus constraining EBS 
design parameters (through minimization of the use of cement) and coupled process models. The 
ability of the multicomponent reactive transport simulations to reproduce observed water-rock 
interactions for the alkaline plumes at Maqarin provides confidence that similar THC modeling 
efforts at Yucca Mountain predict reactive chemistry and transport processes that are expected to 
occur over time. 
7.3.2 Natural Analogues for Colloidal Transport of Radionuclides 
Colloids can facilitate radionuclide transport (Figure 7-6) if they are: (1) present in sufficient 
quantities, (2) mobile, and (3) can bind radionuclides (Wieland and Spieler 2001 [157442], 
p. 511). Naturally occurring colloids are ubiquitous in groundwaters; those sampled by Kingston 
and Whitbeck (1991 [113930], pp. 26, 57) (mainly from central and southern Nevada) have 
dilute colloid concentrations ranging from 0.281.35 mg/L. Ferric oxide and oxyhydroxide 
colloids can also be generated through degradation of structural steel present in EBS materials. 
Filtration of Fe-bearing colloids has been documented in some environments. For instance, 
groundwaters in the Poos de Caldas area, Brazil, typically have low concentrations (<1 mg/L) 
of colloids (Miekeley et al. 1989 [126083], pp. 838, 840841; 1991 [127199], pp. 35, 49). Most 
of the colloids there are composed of iron and organic species. Only minor amounts of uranium 
are associated with colloids, but greater amounts of thorium and rare earth elements are 
transported in the colloidal fraction. The results of the colloid studies at Poos de Caldas 
(Miekeley et al. 1989 [126083], p. 841; 1991 [127199], p. 58) suggest that radionuclide and other 
trace-element transport by colloids does not play a significant role in the geochemical processes 
of weathering, dissolution, and erosion of these ore deposits. One reason for this could be 
filtration of material which traps colloids in pore throats and narrow fractures (Smellie et al. 
1989 [126636], p. 868). The colloidal material acts as an efficient and largely irreversible sink or 
trap for many elements (especially if they are immobile), but needs to be taken into account in 
equilibrium thermodynamic modeling of radionuclide speciation. The point of this example is 
that the iron-bearing colloids that may form in the Exploratory Studies Facility could be 
beneficial in complexing with uranium and could be retained effectively in the EBS by filtration. 
7.4 SUMMARY 
The highly corrosive-resistant nature of titanium has been demonstrated by long-term 
experiments conducted on a range of metal alloys in wells at the Salton Sea geothermal field. 
The commercial use of titanium alloys in production casings over the past decade at the Salton 
Sea has greatly alleviated severe corrosion problems that were previously experienced resulting 
from exposure of conventional steel casing to the hot, hypersaline geothermal brines. This 
anthropogenic example supports the selection of titanium alloys for the construction of a 
corrosion-resistant drip shield for the EBS. 

Mineralogic and geochemical analysis of tuffs in the UZ at Yucca Mountain indicates that the 
presence of zeolite and clay minerals greatly enhance cation exchange, thus serving to retard the 
transport of some radionuclides. While the proposed material (devitrified welded tuff) for the 
invert ballast in the current design does not have high concentrations of these minerals, the high 
surface area of crushed tuff will retard radionuclide transport through absorption. The Los 
Alamos example of actinide absorption in a gravel bed provides qualitative evidence of 
retardation at the contact between an invert-like material and underlying bedrock. 
The presence of cementitious materials can potentially lead to the development of alkaline 
plumes, resulting in corrosion of waste package materials, alteration of surrounding host rocks, 
and possible enhancement of radionuclide transport. Because the use of cementitious material in 
the EBS and its environs is restricted to grout for securing rock bolts in the emplacement drifts, 
hyperalkaline conditions are not expected to develop at Yucca Mountain. However, through 
reactive transport modeling of the Maqarin site, it has been demonstrated that a model can 
reproduce the same suite of cement minerals, hyperalkaline water compositions, and pH that 
were found in the field, thus building confidence in use of such a model for analogous conditions 
at other sites. 
The Poos de Caldas analogue illustrated that iron-bearing colloids may retard the transport of 
uranium and other spent-fuel components by forming colloids that are then filtered from 
suspension at short distances. Degradation of steel structural elements in the EBS could 
conceivably contribute to this process. 

Source: Miller et al. 2000 [156684], Figure B10.2. 
Figure 7-1. Portion of Hadrians Wall in England, Showing Strength and Stability of Roman Mortar after 
1,700 Years 

NOTE: Shaded bars represent corresponding compositions of unzeolitized precursor tuffs. Symbols (Q = quartz, T 
= tridymite, C = cristobalite, F = feldspar) indicate devitrification minerals in welded tuff intervals. UZ-SZ line 
marks location of water table. Chemical abundances are normalized to anhydrous (anh) compositions. 
Source: Vaniman et al. 2000 [157427], Figure 4. 
Figure 7-2. Stratigraphic Section of Drill Hole UE-25 UZ#16, with Abundance of Zeolites Plotted versus 
(a) Alkaline Earth and (b) Alkali Constituents 
Source: Nyhan et al. 1985 [157447], Figure 1. 
Figure 7-3. Cross Section of Absorption Bed for Disposal of Radioactive Liquid Wastes, Area T, DP West 
Site, Los Alamos National Laboratory 

(b) 
Source: Nyhan et al. 1985 [157447], Figures 2 and 3. 
Figure 7-4. Concentrations of Plutonium (a) and Americium-241 (b) within and beneath Absorption Beds 
1 and 2, Area T, DP West Site, Los Alamos National Laboratory (1978) 

Source: Steefel and Lichtner 1998 [156714], Figure 6. 
Figure 7-5. Fracture Mineralization and Wall Rock Alteration at C353 Site, Maqarin, Showing the 
Presence of Hydrated Calcium Silicate and Sulfate Phases Thaumasite and Ettringite 
NOTE: N = dissolved radionuclides in fracture, 
sN = radionuclides on fracture surface, 
Nm = radionuclides bound to mobile colloids, 
sim = radionuclides sorbed on immobile colloids, 
NP = dissolved radionuclides in pores of rock matrix, 
sp = radionuclides sorbed on rock matrix. 
Source: Modified from Jen and Li 2001 [157463], Figure 1. 
Figure 7-6. Schematic Illustration of Radionuclide Transport in a Fractured Rock 

8. NATURAL ANALOGUES FOR SEEPAGE 
8.1 INTRODUCTION 
This section examines several different types of qualitative and quantitative natural analogues for 
seepage, taken from caves, lava tubes, tombs, rock shelters, and buildings that were investigated 
since publication of the FY 01 Supplemental Science and Performance Analyses [SSPA], Volume 
1: Scientific Bases and Analyses (BSC 2001 [155950]). It considers the role of the 
hydrogeologic setting of underground openings on seepage and the effect of relative humidity. It 
evaluates a number of candidate settings that have been suggested as analogues and demonstrates 
why they are or are not considered appropriate as seepage analogues. It also examines the 
question of the preponderance of evidence of preservation of seepage analogues. In this section, 
the term infiltration is used for precipitation that is not lost by runoff, evaporation, or 
transpiration, and seepage is used for that portion of the infiltration within the unsaturated zone 
(UZ) that enters tunnels or other underground openings. For reference, current precipitation at 
Yucca Mountain is about 190 mm/yr (DOE 2001 [153849], Section 4.2.1.2.1), with future rates 
predicted to be 269 to 529 mm/yr (BSC 2001 [155950], Table 3.3.1-5). Information found in 
Sections 8.2, 8.3, and 8.4 may help to support arguments associated with Key Technical Issue 
(KTI) KUZ0407 found in Table 1-1. 
8.2 GEOLOGIC EXAMPLES 
Seepage is mainly governed by the capability of individual fractures to hold water by capillary 
forces, and by the permeability and connectivity of the fracture network, which enables water to 
be diverted around a drift or underground opening. Both properties determine the effectiveness 
of the capillary barrier in diverting flow and thus reducing seepage rates below the prevailing 
percolation flux. Percolation is the downward or lateral flow of water that becomes net 
infiltration in the UZ. The physical properties of water, together with the hydrologic properties of 
rock, lead to the prediction that much of the infiltrating water in the UZ will be preferentially 
diverted around openings, such as tunnels, at the Yucca Mountain repository. The percentage of 
infiltration that can become seepage decreases as infiltration decreases, and at low infiltration 
rates (<5 mm/yr) and most permeabilities, no seepage occurs (DOE 2001 [153849], Section 
4.2.1.4.2). Two natural analogue studies confirm the prediction that most infiltration does not 
become seepage. 
In a two-year study at Kartchner Caverns, Arizona, yearly precipitation ranged from 288 mm to 
607 mm, and averaged 448 mm/yr (Buecher 1999 [154295], pp. 108109). This average was 
similar to the long-term average at two nearby stations. Estimates of seepage into the cave by 
three methods based on infiltration and precipitation measurements ranged from 4.3 mm/yr to 
12.4 mm/yr, with an average of 7.9 mm/yr (Buecher 1999 [154295], p. 110). Thus, less than 2% 
of the available moisture became seepage. This low seepage occurs even though the cave, which 
covers an area of approximately 350 m (N-S) by 550 m (E-W), is cut by more than 60 mapped 
faults (Jagnow 1999 [154296], p. 49 and Figure 3). 
The cave at Altamira, Spain, was monitored for 22 months by Villar et al. (1985 [145806]). The 
volume of water flowing from 9 of 14 significant drips was measured, and an average total 

seepage of 7 liters/mo was reported. This volume is estimated to represent about 80% of the total 
seepage (Stuckless 2000 [151957], p. 6), which would bring the total seepage rate up to almost 9 
liters/mo. Villar et al. (1985 [145806], Figure 4) also measured the average rainfall. Based on the 
data from Villar et al. (1985 [145806], Figure 4), the average annual rainfall was calculated to be 
approximately 1152 mm/yr or 1152 liters/yr/m2 (Simmons 2002 [157544], p. 144). The average 
evapotranspiration was calculated as approximately 660 mm/yr (660 liters/yr/m2), which results 
in an average net infiltration of about 480 mm/yr (480 liters/yr/m2). The area of the painted cave 
studied was reported as 150 m2, which would result in a monthly volume of infiltration water of 
about 6,000 liters/mo above the footprint of the area studied in the cave (Simmons 2002 
[157544], pp. 143144). As was the case at Kartchner Caverns, the rock is obviously fractured 
(Figure 8-1). Nonetheless, less than 1% of the infiltrating water seeped into the cave. The fact 
that the paintings have not been bleached or dissolved near the fractures suggests that little water 
has seeped in along fractures during the last 14,000 yrs, which is the age of the paintings 
(Stuckless 2000 [151957], p. 8). 
Both of these examples are from limestone caves in fractured karst terrain. It follows from these 
examples that UZ flow would be dominated by fracture flow, just as it is at Yucca Mountain. 
Both caves are much closer to the surface than the Yucca Mountain repository horizon, and 
therefore, there is a much greater probability for fractures to communicate directly between the 
underground opening and the surface, thereby facilitating seepage. At the caves, a pulse of water 
enters at peak saturation, whereas at the potential repository horizon the amplitude of the water 
pulse is attenuated because of the damping effect of the PTn (BSC 2001 [155950], Section 
3.3.3.1). This damping effect yields lower average saturations that are less conducive to seepage. 
At both Altamira and Kartchner Caverns, precipitation exceeds current rates at Yucca Mountain 
and those predicted for future climates as well. Thus, the observational data from these natural 
analogues support the conclusion that seepage into the repository at Yucca Mountain would be a 
very small percentage of the percolation flux, which will therefore result in a very small volume 
of water entering drifts. 
8.3 ARCHEOLOGICAL EXAMPLES 
The long-term quantitative hydrologic studies such as those cited above are not common, but 
there is abundant qualitative evidence that openings in the UZ divert much infiltration, thereby 
protecting fragile and easily destroyed items. The examples that follow are from both natural and 
man-made underground openings and include preservation of both anthropogenic and biological 
materials. The examples chosen are representative and are not meant to constitute an exhaustive 
listing. 
The oldest and perhaps the best known examples of preservation of anthropogenic items within 
the UZ are the Paleolithic cave paintings of southwestern Europe. The Paleolithic cultural period 
lasted from 750,000 to 15,000 years ago. There are dozens of caves with paintings (Stuckless 
2000 [151957], Figure 1); the oldest of those authenticated is the cave of Chauvet, France 
(Figure 8-2). The cave is located in a subhumid region, with reported precipitation totals within 
the region ranging from 580 to 780 mm/yr (Stuckless 2000 [151957], p. 3). The Chauvet cave 
paintings depict animals that are now extinct, such as mammoths, and other species that no 
longer live in Europe, such as rhinoceroses (Chauvet et al. 1996 [152249]), which attest to a 
much different paleoclimate from the climate at present. The paintings in the French caves were 

made largely with oxides of iron and other minor constituents (Leroi-Gourhan 1982 [156454] p. 
105; Ruspoli 1987 [156223], pp. 192193). Charcoal or manganese oxide was commonly used 
for black. Neither the iron and manganese oxide nor charcoal would be expected to survive long 
in the presence of abundant oxidizing water. This is evidenced by a painted block that fell from a 
painting of a bull at Lascaux, France, and lay painted side down on the damp floor. Although the 
block fit back into the painting, it had lost all evidence of paint (Breisch 1987 [156456], p. 286). 
Well-preserved Paleolithic art is common only in the caves of southern Europe, but examples of 
late Paleolithic and, more commonly, Neolithic art from the Neolithic cultural period that began 
about 10,000 B.C. are known throughout the world. Stuckless (2000 [151957]) provides a 
summary and references for paintings in Africa, South America, North America, and Asia. In 
most of the world, painted rock shelters are more common than painted caves, which 
demonstrates that even a few meters of overhang can protect fragile art from infiltration water 
(Stuckless 2000 [151957], p. 9). 
In addition to paintings, caves have preserved fragile artifacts such as the 14,000-year-old clay 
bison in a cave near Tuc dAudoubert, France (Stuckless 2000 [151957], Figure 3). Some caves 
are located in zones of such low percolation flux that they have little, if any, measurable seepage 
flux. This supports another part of the UZ flow model in which seepage is predicted to decrease 
with a decrease in infiltration. Caves in Israel provide an example of this, where cloth, ivory, 
reed mats, and many bronze items have been preserved in a nearly perfect state (Schick 1998 
[156641], Color Plates 3.73.9; Ozment 1999 [155058], pp. 7475). These date from about 3,800 
B.C., and although the climate is currently drier than that at Yucca Mountain, the preservation 
demonstrates that the lack of water allows even easily destroyed items to endure for long periods 
of time and suggests that the predicted zero seepage at low infiltration rates is likely correct. 
Relatively dry caves are common throughout the southwestern United States. Because of the 
dryness, pollen and other delicate plant and animal materials have been preserved for tens of 
thousands to hundreds of thousands of years (Davis 1990 [144461]; Rogers et al. 2000 [154320]) 
in caves and lava tubes, respectively. In fact, Davis (1990 [144461], p. 338) notes that dryness in 
caves is critical to preservation of biotic remains. For example, at Spirit Cave, Nevada, a 9,000- 
year-old mummy was discovered (Dansie 1997 [152137]. The body was well-preserved, with 
body and hair remaining. That such preservation is common is supported by the fact that over 
1,000 packrat middens have been studied throughout semi-arid to arid North America, and some 
of these are older than 40,000 yrs (Davis 1990 [144461], p. 341). The middens are cemented 
with dried urine, which would dissolve readily in water. Nonetheless, the middens older than 
about 20,000 yrs (some of these were found near Yucca Mountain) have survived much wetter 
past climates, similar to those predicted for the future climate at Yucca Mountain, indicating that 
over a long period of time, little seepage has entered the openings where middens were found. 
Underground openings in the UZ have been excavated by early civilizations, but these examples 
are generally much younger than those from natural systems. Nevertheless, they also provide 
evidence of the robust protection provided against the effects of water. In addition, these 
anthropogenic examples broaden the range of geologic settings that can be examined as 
analogues for a potential repository at Yucca Mountain. 

Man-made underground openings include the Egyptian tombs across the Nile River from Luxor. 
These were excavated in limestone approximately 3,500 to 3,000 years ago. As noted in Section 
8.2, limestone is hydrologically similar in fracturing and low matrix porosity to the welded tuffs 
of Yucca Mountain. Although the climate is somewhat drier than that at Yucca Mountain, 
precipitation events have been strong enough to cause mud flows within the Valley of the Kings 
(Weeks 1998 [154297], pp. 10, 11). Seepage into the tombs is indicated by small areas of 
spallation of plaster, which can be seen in many tombs for both areas of wall and ceilings (Figure 
8-3), but evidence of dripping, such as efflorescence or stalactitic formations, seems to be 
lacking. 
Buddhist monks carved several temples into basalt flows at Ajanta, India, between the second 
century B.C. and the tenth century A.D. (Behl 1998 [156213], p. 27, 39). Water flow within the 
basalts would, as at Yucca Mountain, be dominated by fracture flow. The interiors of the temples 
are painted. The paintings were done on a plaster that consisted of mud, rock dust, and vegetable 
fiber. The climate at Ajanta is monsoonal, such that the precipitation (800 mm/yr), which is more 
than four times that at Yucca Mountain (Section 8.1), falls in four months (Stuckless 2000 
[151957], p. 19). Nonetheless, many of the paintings are well preserved, except for small areas of 
spallation (Figure 8-4). 
The Christians of Cappadocia, Turkey, excavated underground cities and churches during the 
second through eleventh centuries A.D. The geology here is similar to that of southern Nevada in 
that the bedrock is a thick sequence of silicic volcanic rocks. Visits to the underground cities and 
churches produced no evidence of dripping from the ceiling, but evidence for flow down a wall 
was found where a fracture intersected the wall (Stuckless 2000 [151957], p. 22). As with the 
Egyptian tombs and Buddhist temples, some of the church paintings showed evidence of 
spallation (Figure 8-5). 
The caves at Carlsbad Caverns, New Mexico have stood open for as much as 11 m.y. (Polyak et 
al. 1998 [156159], p. 1919). During that time, seepage occurred as evidenced by stalactites, 
stalagmites, and flowstone. Today, only a small percentage of the seeps are active in spite of an 
average precipitation of approximately 500 mm/yr. This is more than twice the amount currently 
observed at Yucca Mountain and larger than that predicted for likely future climates. 
In addition to showing that most infiltration does not become seepage, natural analogues 
demonstrate that much of the seepage that does occur stays on the walls rather than dripping into 
the openings. Figures 8-2 and 8-3 show evidence of water flow down walls. Figure 8-6 shows the 
soot-covered wall and ceiling of a kitchen excavated in the tuffs of Goreme (Cappadocia region), 
Turkey. The soot deposited along the fracture in the ceiling has been bleached out, presumably 
because of infiltrating oxygenated water. Stalagtitic deposits that might indicate dripping water 
do not exist, but the removal of soot below the fracture on the wall would have to be caused by 
some flow of water down the wall. 
Perhaps the best analogue for water that might seep into the tunnels at Yucca Mountain can be 
seen at Building 810 in the Denver Federal Center, Colorado (Figure 8-7a). The roof of this 
building is constructed of a series of arches called barrels. Each represents a segment of a 
cylinder with a diameter of 25 ft, the same diameter as the Exploratory Studies Facility (ESF) at 
Yucca Mountain. As shown by the white efflorescent salt deposits, water has seeped through the 

roof over the loading dock along fractures in the concrete and then flowed on the underside of 
the roof, until it either evaporates or reaches the vertical sections along the sides of the barrels, 
where it can drip. The undersurface shown in Figure 8-7b is smoother than much of the ESF 
tunnel, and thus it may be more effective in diverting seepage to the walls. In contrast, the 
roughness of the ESF walls may cause asperities that could focus drips. Nonetheless, it 
demonstrates how seepage could be directed in the tunnels. 
8.4 EVALUATING THE ANALOGUES 
Although there are many examples of Paleolithic and Neolithic art preserved in caves, questions 
persist about whether an equal or perhaps even larger number of paintings have been completely 
destroyed. Null evidence is difficult to evaluate, but a few lines of evidence suggest that 
paintings have not been totally destroyed in caves where they may have once existed. 
First, if paintings had been completely destroyed in some caves, or even parts of caves, one 
would expect most, if not all, localities to exhibit either a spectrum of preservation from largely 
destroyed to fully preserved paintings. Alternatively, there should be an explanation for the 
binary distribution. A variety in the degrees of preservation of cave art was not found in the 
current literature search, either within individual caves or in the body of literature as a whole. A 
cave at Palomera in Burgos, Spain, like the cave at Cosquer, has had some paintings removed by 
water while others are in good condition. This cave, which has paintings dated at 10,950 +/- 100 
to 11,540 +/- 100 B.P. (Corchon et al. 1996 [156636], pp. 4144), has at times had a stream 
flowing in it that has left organic debris plastered to heights of several meters on the walls. The 
flooding is younger than the paintings and has apparently destroyed the paintings to the height of 
the flooding. Lascaux provides another example where one gallery has had over 90% of the 
paintings removed by wind abrasion (Breisch 1987 [156456], p. 286). 
Second, areas where paintings would be least likely to survive, such as drip sites in the ceiling or 
flow channels on the walls of caves, have probably been the loci of flow for thousands of years. 
Early man would likely have avoided these areas, because they were too wet to paint. Exceptions 
to this hypothesis are known. For example, one painting on the ceiling at Chauvet is partly 
covered by stalactitic calcite (Chauvet et al. 1996 [152249], p. 47). Some paintings have thin 
coatings of calcite caused by evaporation of thin films of water. 
Finally, the shear number of painted caves and the number of paintings in some of the caves 
argues for a high degree of preservation. In France and Spain alone, there are more than 150 
painted caves (Ruspoli 1987 [156223], p. 18). Grand (1967 [156218], p. 28) reports over 2,188 
paintings of animals in 110 caves. 
In the case of rock shelters, some observational data correlate with preservation or destruction. In 
sandstone shelters in India, the roots of banyan trees have been noted to provide a preferential 
path for water across a painting. The part of the painting exposed to water has been encrusted 
with calcium deposits, while leaving another part of the same figureuntouched by water 
unscathed (Neumayer 1983 [156221], p. 6). 
Not all underground openings provide appropriate analogues. The previous examples of caves 
and underground openings were all less than 100 m from the surface. The Mission Tunnel 

through the Santa Ynez Mountains near Santa Barbara, California, is closer in depth (200 to 670 
m from the surface) to the potential mined geologic repository (300 m depth), as compared to the 
previous examples. The Mission Tunnel exhibits rapid response to precipitation events and large 
amounts of seepage flux (1.23 million m3/yr; Boles 1999 [156635]). Unfortunately, quantitative 
measurements have not been made, so the percentage of infiltration that becomes seepage is 
unknown. However, the apparently large amounts of seepage into the Mission Tunnel are caused 
by flow paths that are within nearly vertical, highly transmissive, fractured sandstone units 
(Boles 1999 [156635]). Furthermore, at least some part of the flow could be from groundwater 
seeps below the water table (Boles 1999 [156635]). Thus, the hydrogeology for this potential 
analogue is drastically different from that for the potential repository at Yucca Mountain, where 
the hydrologic units are gently dipping and few through-going fractures have a hydrologic 
connection with the surface. 
Mitchell Caverns, located on the eastern slope of the Providence Mountains in the East Mojave 
National Preserve, California, may also be a potential location for study of seepage. The caverns 
are found at an elevation of 1,341 m (4,400 ft; Pinto 1989 [156638], p. 6) in a wedge of Permian 
limestone (approximately 300 Ma; Norris 1999 [156637], p. 10). The limestone layers are 
upended, folded, and highly fractured by intrusion of younger Jurassic quartz monzonite 
(approximately 160 Ma; Miller et al. 1991 [156458], Plate 1). 
The larger of the caves accessible to the public, Tecopa, exhibits soda straw features, which are 
hollow stalactites in early stages of development. Tecopa, however, is a drier cave than the other 
publicly accessible cave, El Pakiva, and is said to be aging. Because Tecopa has two entrances, it 
is more influenced by the surface environment than is El Pakiva cave, which tends to dry out 
more quickly after a rainfall. Approximately 10 drip locations were observed to begin a few days 
after a rainfall. All but one of these are in El Pakiva Cave, which is less than 30 m (100 ft) from 
the surface (Simmons 2002 [157544], pp. 124125). 
The speleothems at Mitchell Caverns are nearly inactive under present climate conditions; there 
are no continuous seeps. The caves respond rapidly after a rainfall. Dripping can be observed to 
last from a variety of locations up to 28 days after a heavy rainfall (Simmons 2002 [157544], p. 
126). Mean annual precipitation measured at the caverns is 18.6 cm (Stein and Warrick 1979 
[156642], p. 12). 
Because the fractured limestone in which Mitchell Caverns are situated has rapid communication 
with the ground surface along fracture flow paths after a rainfall, and because there is a 
considerable bedrock catchment basin above the caves that would induce seepage, they are not 
an ideal analogue to the conditions expected at Yucca Mountain. Instead, Mitchell Caverns may 
provide an intermediate analogue between the cave at Altamira, Spain, where very little water 
has seeped along fractures, and the Mission Tunnel, California, which experiences heavy flow 
along numerous surface-intersecting pathways. 
8.5 SUMMARY OF SEEPAGE ANALOGUES 
One important variable for preservation in underground openings is relative humidity. It is 
obvious that if relative humidity in the drift is kept below 100% by ventilation, then seepage of 
liquid water would be reduced or completely suppressed. Most caves are close to but below 

100% humidity (e.g., Kartchner RH=99.4 % (Buecher 1999 [154295], p. 111); Altimira RH=98 
+/- 2% (Breisch 1987 [156456], p. 290; Quindos 1987 [156640], p. 555)). These caves are 
naturally ventilated; thus, the amount of seepage in these caves would be expected to be low. 
This would also be true at Yucca Mountain while ventilation is maintained. 
This section has examined several different types of qualitative and quantitative natural 
analogues. The findings support the hypothesis that most of the infiltrating water in the UZ is 
diverted around underground openings and does not become seepage. The analogues show that 
this is true even for areas with much greater precipitation rates than that at Yucca Mountain. 
Although examples exist where large amounts of seepage can be observed (e.g., the Mission 
Tunnel and Mitchell Caverns), the hydrogeologic setting is significantly different from that at 
Yucca Mountain, and thus, these are not appropriate analogues. However, for all of the 
analogues that show some seepage, at least some of the seepage that enters underground 
openings does not drip, but rather flows down the walls. In the few instances where dripping has 
been noted in settings that are analogous to Yucca Mountain, the drips can be attributed to 
asperities in the surface of the roof and ceiling of the opening. Whether water flows on walls or 
drips depends on conditions affecting drop formation and drop detachment (e.g., surface tension, 
roughness angle, saturation). Thus, by analogy at Yucca Mountain, although most water would 
flow around emplacement drifts, the small amount of seepage that would occur would primarily 
flow down tunnel walls. In the few instances where dripping may occur, it would be expected to 
be attributable to asperities in the tunnel ceilings. 

NOTE: There is no apparent water damage near fractures through both the iron oxide 
and charcoal portions of the 14,000-year-old painting. 
Source: Stuckless 2000 [151957], p. 8. 
Figure 8-1. Painted Bison from the Ceiling of the Cave at Altamira, Spain 

NOTE: Although there is evidence of water flow down the wall, in general, there is still 
good preservation. 
Source: Chauvet et al. 1996 [152249], Figure 49 (used with permission of the French 
Ministry of Antiquity). 
Figure 8-2. 32,000-year-old Painted Auroches and Horses from Chauvet Cave 

NOTE: The tomb shows no evidence of dripping from the ceiling, but plaster on the wall 
has been damaged by moisture, and some of the paint shows evidence of water 
running down the wall. The tomb was excavated in limestone about 1,400 B.C. 
Source: Simmons 2002 [157544], p. 141. 
Figure 8-3. The Painted Interior of the Tomb of Sennefer 

NOTE: The hexagonal column is from the second century B.C. 
Source: Behl 1998 [156213], p. 42. 
Figure 8-4. Painting from the Underground Ajanta Temple in India Is Fairly Well Preserved in Spite of 
Its Age and the Wet Climate 

NOTE: The perfectly preserved painting on the left was painted in the eleventh century A.D. The painting 
on the right shows damage from vandals and from spallation of the plaster. 
Source: Stuckless 2000 [151957], p. 23. 
Figure 8-5. Frescoes on the Ceiling and Walls of the Karanlik Church at Goreme, Turkey, Show 
Varying Degrees of Preservation But No Evidence of Dripping from the Ceiling 

NOTE: The kitchen was excavated into ash flow tuff and was probably in use until the 
twelfth century A.D. The soot has been removed adjacent to the fracture in the 
ceiling, possibly by oxidation. Flow has occurred down the wall, as evidenced by 
removal of some of the soot below the fracture. 
Source: Stuckless 2000 [151957], p. 24. 
Figure 8-6. Photograph and Drawing of a Fracture in the Blackened Wall and Ceiling of a Kitchen in a 
Subterranean Monastery at Goreme, Turkey 

a) 
b) 
NOTE: Water has seeped along joints in the concrete, but rather than dripping, it has 
flowed along the curvature of the roof. 
Source: Simmons 2002 [157544], p. 142. 
Figure 8-7. Photograph of Building 810 in the Denver Federal Center, Colorado (a), and Close-up of the 
Underside of the Roof over the Loading Dock (b) 

9. ANALOGUES FOR UNSATURATED ZONE FLOW 
9.1 INTRODUCTION 
The conceptual and numerical modeling methodologies for the unsaturated zone (UZ) at Yucca 
Mountain are applicable to other sites, including Apache Leap (Arizona), Box Canyon (Idaho), 
Rainier Mesa (Nevada), and other semi-arid sites in fractured rock. These and other examples are 
presented in Natural Analogs for the Unsaturated Zone (CRWMS M&O 2000 [141407]) and in 
the Yucca Mountain Site Description (CRWMS M&O 2000 [151945], Sec. 13). Analogues for 
climate and infiltration processes are presented in the Yucca Mountain Science and Engineering 
Report (S&ER) (DOE 2001 [153849], Table 4-5). Analogues for UZ flow and seepage processes 
are listed in the S&ER (DOE 2001 [153849], Table 4-6). In general, these analogues contribute 
to providing confidence in the understanding of paleoclimatic conditions, the bounds on various 
climate models, the efficacy of a UZ in isolating nuclear waste, the occurrence of very limited 
seepage in the UZ, and limited fracture-matrix interactions. 
Section 9 presents results of a quantitative analogue investigation that had the objective of 
utilizing related data sets gathered at the Idaho National Engineering and Environmental 
Laboratory (INEEL) to test the dual-permeability approach of the Yucca Mountain UZ flow 
model at another site in an attempt to match results of field tests, thus building confidence in the 
UZ modeling approach. This section also presents a number of possible locations and 
configurations for testing the drift shadow zone concept in analogous settings and conditions. 
9.2 UZ FLOW MODEL 
The Yucca Mountain UZ flow model is described in Unsaturated Zone Flow and Transport 
Model Process Model Report (UZ PMR) (CRWMS M&O 2000 [151940]) and in the S&ER 
(DOE 2001 [153849], Section 4.2.1). Available site data are used to provide infiltration and 
percolation flux distributions and hydrologic properties. The UZ flow model accounts for the 
occurrence of perched water and the effects of the PTn unit and fault zones on flow in the UZ. 
Upper bound limits on infiltration rates and percolation fluxes at Yucca Mountain are estimated 
based on multiple approaches, including analyses of chloride and chlorine-36 isotopic ratios, 
calcite deposition, and the occurrence of perched water. The analysis of chloride data indicates 
that the average percolation rate over the model domain at Yucca Mountain is about 4.6 mm/yr. 
Analysis of calcite deposition gives infiltration rates of 2 to 20 mm/yr in the vicinity of borehole 
USW WT-24. To match perched water occurrences, three-dimensional model calibrations 
require that the present-day infiltration rate be greater than 1 mm/yr, with an upper limit of about 
15 mm/yr (DOE 2001 [153849], Section 4.2.1.3.2). Infiltration and flow patterns at Yucca 
Mountain are summarized below. 
Rainfall for the modern mean climate is about 190 mm/yr (7.5 in/yr) resulting in average steadystate 
net infiltration of 4.6 mm/yr (0.18 in/yr, DOE 2001 [153849], Table 4-11). The net 
infiltration is episodic, with a significant amount infiltrating only every few years. There is large 
spatial variability of infiltration, with most water infiltrating on ridge-tops and in the upper 
reaches of washes where there is little alluvial cover. Fracture flow dominates in the Tiva 
Canyon welded hydrogeologic unit (TCw), transmitting water rapidly through the TCw to the 

underlying Paintbrush tuff nonwelded hydrogeologic unit (PTn). Flow through the PTn is 
primarily matrix flow with most of the fast flow occurring via faults, although this represents 
only a very small fraction of the total flow. Some lateral flow occurs in the PTn. 
Episodic flow into the Topopah Spring welded hydrogeologic unit (TSw) is damped by the PTn 
to the extent that flow can be considered steady-state at the boundary with the TSw. However, at 
or near major faults, episodic flow may still persist through the PTn. Fracture flow dominates in 
the TSw because this unit is densely welded and highly fractured; additionally, within some 
subunits of the TSw, the low-permeability matrix is incapable of transmitting the percolation flux 
estimated to be moving through the unit. Fracture flow in the potential repository horizon, which 
intersects the Topopah Spring middle nonlithophysal, lower lithophysal and lower 
nonlithophysal stratigraphic units, is estimated to range from 84 to 94 percent of the total water 
flow. 
Water drainage in the potential repository units is expected to be good, owing to the generally 
high fracture permeability (~10-11 to 10-10 m2 [10-10 to 10-9 ft2]) (DOE 2001 [153849], Section 
4.2.1.2.5). Evidence for fast or preferential flow is seen at the potential repository horizon, 
primarily near major faults. It is estimated that the fast component of flow is less than a few 
percent of the total flow. 
9.3 THE SUBSURFACE DISPOSAL AREA AT THE IDAHO NATIONAL 
ENGINEERING AND ENVIRONMENTAL LABORATORY AS AN ANALOGUE 
FOR TESTING YUCCA MOUNTAIN MODELING APPROACHES 
This section discusses modeling of UZ flow and tracer tests at INEEL. Modeling of UZ transport 
at this site is discussed in Section 10. Section 9.3.1 provides information on the geologic and 
hydrologic setting of the Radioactive Waste Management Complex (RWMC) at INEEL as 
background for a flow modeling study in Section 9.3.2 and a radioactive transport model in 
Section 10.3. Further discussion comparing similarities and differences between INEEL and 
Yucca Mountain is found in Section 10.3.5. 
9.3.1 Background 
Between 1952 and 1986, approximately 180,000 m3 of transuranic and low-level radioactive 
mixed wastes, containing about 9.5 million curies of radioactivity, were buried in unlined 
trenches and pits in shallow sediment above basalt flows at the INEEL in the 144,100 m2 
Subsurface Disposal Area (SDA) of the Radioactive Waste Management Complex (RWMC) 
(Cecil et al. 1992 [156256], p. 709). Included with these buried wastes were approximately 
334,000 liters of transuranic-contaminated mixed-waste sludges that were absorbed on calcium 
silicate and placed in 55-gallon steel drums (Rawson et al. 1991 [156439]). Since 1970, 
transuranic wastes have been stored in containers placed above ground on asphalt pads in a part 
of the RWMC known as the transuranic disposal area. Subsurface disposal of radioactive waste 
at the SDA is planned to continue until at least 2003 (INEL 1995 [156430]). Environmental 
monitoring beneath the SDA in both the UZ and saturated zones (SZ) has resulted in positive 
detections of americium, plutonium, and other waste products that have migrated from the SDA 
(Dames and Moore 1992 [157409], pp. 7374; Becker et al. 1998 [157407], pp. 4-36 to 4-37), 
thereby raising concerns about the long-term water quality of the Snake River Plain Aquifer 

(SRPA), the principal source of potable groundwater in the area. Effort is underway to evaluate 
the long-term risk posed to the aquifer by past waste-disposal practices (Magnuson and Sondrup 
1998 [156431]; Becker et al. 1998 [157407]) and to determine the necessity of potentially costly 
remedial strategies, including exhumation and redisposal of the buried waste. 
9.3.1.1 Geologic and Hydrologic Setting 
The geologic and hydrologic setting of the RWMC has been described in a series of reports by 
the U.S. Geological Survey (USGS) and the U.S. Department of Energy (DOE) and its 
contractors (e.g., Rightmire and Lewis 1987 [156440]; [156441]; Magnuson and Sondrup 1998 
[156431]). The top of the surficial sediment in which the wastes are buried is approximately 175 
to 180 m above the regional water table. The thick UZ beneath the SDA contains 13 individual 
basalt flows ranging in thickness from less than 1 m to 17 m and averaging about 5 m in 
thickness (Knutson et al. 1990 [107839], p. 21). The individual basalt flows can be subdivided 
into four zones, with varying amounts of rubble, vesicles, and fractures, and grouped on the basis 
of the presence of three major sedimentary interbeds. Three sedimentary interbeds at 9 m, 34 m, 
and 73 m have been used to subdivide the basalts into A-, B-, C-, and D-group basalts; 
correspondingly, the 9 m, 34 m, and 73 m interbeds are alternatively known as the A-B, B-C, and 
C-D sediment layers (Figure 9.3-1). 
Annual precipitation at INEEL ranges from 13 to 36 cm/yr, with an average of 20 cm/yr. About 
30 percent of the annual precipitation typically occurs as snow (Barraclough et al. 1976 
[156426], p. 45). Chlorine-36, tritium, and neutron-logging data from a series of shallow 
boreholes drilled just outside the northern boundary of the SDA provided estimates of 
background infiltration rates for undisturbed soils of 0.36 to 1.1 cm/yr (Cecil et al. 1992 
[156256], p. 709). Infiltration rates within the SDA have been estimated to be higher than the 
background infiltration rates because of the drifting and accumulation of snow within the SDA. 
Based on neutron-probe measurements of soil moisture changes for the years 1994 to 1995 and 
weather data extending back to 1952, Martian (1995 [156432], pp. 3236) estimated that the 
spatially and temporally variable infiltration rates within the SDA have averaged between 6 and 
10 cm/yr since 1952. Only two of the seventeen neutron-probe boreholes were located in the 
soils within the trenches; therefore, moisture content changes and infiltration rates through the 
trench fill are not as well characterized as the areas between the trenches. In addition, the SDA 
has been flooded three times (1962, 1969, and 1982) as a result of the local accumulation of 
overland flow associated with rapid snowmelt (Vigil 1988 [157416], p. 1, 8). Estimates have 
been made of the amounts of water that infiltrated (Vigil 1988 [157416]) and which areas of the 
SDA were flooded (Magnuson and Sondrup 1998 [156431], Figures 217). The average depths 
of the infiltrated water in the flooded areas in the SDA were estimated by Magnuson and 
Sondrup (1998 [156431], Tables 23) to be 0.17 m in 1962, 0.12 m in 1969, and 0.08 m in 1982. 
Perched water has been encountered by boreholes within the SDA at depths that correspond 
roughly to the tops of the sedimentary interbeds (Rightmire and Lewis 1987 [156441], pp. 43 
45, Figure 10). Rightmire and Lewis (1987 [156441], p. 45) proposed a hypothesis that the 
source of at least some of the perched water was actually infiltration from spreading areas, 
located about 1.7 km to the southwest of the SDA. This infiltration migrated laterally in the UZ 
along and across the interbeds. Water is diverted from the Big Lost River into these spreading 
areas during periods of high flow (>14 m3/s) to minimize flooding to downstream areas. Support 

for the hypothesis that the deeper perched water beneath the SDA originated from the spreading 
areas seemed to Rightmire and Lewis (1987 [156441], p. 65) to be provided by delta-deuterium 
(dD) and delta oxygen-18 (d18O) data. The dD and d18O values of the deep perched water 
indicated little evidence for evaporation compared to shallow perched water or to groundwater 
from the regional aquifer, a relation that Rightmire and Lewis (1987 [156441]) considered to be 
consistent with their hypothesis that the deep perched water originated from the rapid infiltration 
(and minimal evaporation) of large amounts of water through the spreading areas. For a 
comparison of the hydrologic settings of INEEL and Yucca Mountain, see Section 10.3.5.1. 
9.3.1.2 Surficial Sediments and Sedimentary Interbeds 
The surficial sediments consist of the undisturbed areas between the waste trenches and the 
trench backfill, which is a mixture of excavated material. In some cases, the trenches and pits 
were originally excavated down to the top of the uppermost basalt layer; however, in these cases 
a sediment buffer ranging in thickness from 0.67 to 1.0 m was placed in the trench between the 
waste and the underlying basalt (Rawson et al. 1991 [156439]). 
9.3.1.2.1 Mineralogy 
The predominant minerals in surficial sediments and sedimentary interbeds are quartz, 
plagioclase with the composition of labradorite, pyroxene (probably augite), potassium feldspar, 
clay, and calcite (Rightmire and Lewis 1987 [156441], p. 11). The percentage of clay is higher 
and the percentages of plagioclase, potassium feldspar, and pyroxene are lower in the surficial 
sediments compared to the sedimentary interbeds. Calcite is often 10% or more by weight of the 
surficial material and sedimentary interbeds (Rightmire and Lewis 1987 [156441], p. 26), with 
much higher percentages of calcite present locally. 
The 9 m interbed (A-B Sediment Layer) contains some organic-rich paleosols, with the organic 
material possibly introduced by infiltrating water, as well as a red color (due to the oxidation of 
ferrous iron derived from minerals in the nearby basalts). The 34 m interbed (B-C Sediment 
Layer) also contains a dark-brown organic-rich soil horizon and caliche, amorphous silica, and 
Ca-smectite. The 73 m interbed (C-D Sediment Layer) has a red color resulting from iron 
oxyhydroxides throughout its entire thickness (Rightmire and Lewis 1987 [156441], pp. 2428). 
A study of the clay mineralogy of the surficial sediment, the sedimentary interbeds, and fill 
material of fractures in the basalt indicated that the dominant clay species are illite, followed by 
mixed illite/smectite, and finally, kaolinite plus chlorite (Rightmire and Lewis 1987 [156441], 
Table 8). The smectite that is present is mainly a calcium smectite (Rightmire and Lewis 1987 
[156441], p. 40). 
9.3.1.2.2 Geochemical Properties 
Four measurements of the cation exchange capacity (CEC) of the surficial sediments ranged 
from 11 to 27 meq/100 g, with an average of 19 meq/100 g (Rightmire and Lewis 1987 
[156441], Table 5). There was no apparent correlation between the CEC and the clay content of 
the sediments. The CEC of the interbed sediments is highly variable (0.9 to 36 meq/100 g) and 

appears to be related to the percentage of the expandable layer clays present as either pure 
smectite or mixed illite/smectite (Rightmire and Lewis 1987 [156441], pp. 3334). 
The distribution coefficient (Kd) values of various radionuclides are given for the surficial 
sediments, sedimentary interbeds, and basalts in Table 9.3-1 (Dicke 1997 [157410], Table 1). 
The Kd values were measured using composite samples from the interbed sediments and crushed 
basalts with the fines removed. The reported values for Am, Cs, Co, Hg, Pu, Sr, Tc, and U were 
based on site-specific data, with values for other elements estimated from the literature or by 
analogy with chemically similar elements (Dicke 1997 [157410], pp. 1011). In cases where 
literature values were used, the data were screened to remove those values obtained using water 
compositions very dissimilar to that of water that is present in the UZ beneath the SDA. Data 
from the literature were also adjusted to reflect differences in the amount and type of clays 
present in the test material and in the surficial and interbed sediments (Dicke 1997 [157410], p. 
5). The data indicate higher Kd values for the sediments, possibly because of a greater amount of 
reactive minerals, such as smectite, in the sediments. Because the interbed sediments were 
combined in a single sample, there is no basis for estimating how the sorptive properties vary 
among the interbeds. 
9.3.1.2.3 Unsaturated-Zone Matric Potentials 
A summary of the matric potentials measured beneath the SDA in the surficial sediments and 
sedimentary interbeds using tensiometers, heat-dissipation probes, and gypsum blocks was 
presented by McElroy and Hubbell (1990 [156433]). In the surficial sediments, the shallowest 
measurements ranged between about -0.2 and -1.3 bars, reflecting seasonal wetting and drying 
cycles. The deepest measurements taken from near the sediment/basalt interface were near 0 
bars, indicating near-saturated conditions. Hydraulic gradients varied over time, ranging between 
upward and downward flow within the upper 1.2 to 3.3 m of the sediment profile, depending on 
the location of the borehole, but were consistently downward beneath this range of depths. 
The equilibrium matric potentials within the 9 m, 34 m, and 73 m interbeds were between -1.4 
and -0.3 bars. In general, wetter conditions existed at the tops of the interbeds compared to the 
bottoms, and hydraulic gradients across the interbeds were greater than unity. 
9.3.1.2.4 Unsaturated-Zone Gas Chemistry 
Soil gas samples taken from a 0.3 to 0.76 m depth in the surficial sediment at a site 
approximately 11 miles from the SDA were reported by Rightmire and Lewis (1987 [156441], 
Table 12). The data from this site may be representative of conditions at the SDA prior to its 
development as a waste disposal area. The chemistry of the soil gas samples closely resembled 
the chemistry of air, except for CO2(g), whose concentration in the soil gas was several times 
higher than in the atmosphere. The logarithm of carbon dioxide partial pressure (log PCO2) and 
the delta carbon-13 value (d13C) of the CO2(g) were observed to vary seasonally and with depth 
in the soil zone. Rightmire and Lewis (1987 [156441], p. 59) concluded that log PCO2 values 
(expressed as bar) of -2.84 to -3.04, and d13C values of -15.5 to -19.6 per mil were characteristic 
of shallow soil zone gas in late spring, summer, and early autumn, and that log PCO2 values of 
-2.97 to -3.09, and d13C values of -16.4 to -17.2 per mil were characteristic of shallow soil zone 
gas in early spring. Snow melt in early spring has been hypothesized to be the principal source of 

recharge at the SDA (Rightmire and Lewis 1987 [156441], p. 59). A comparison of the 
geochemical settings of INEEL and Yucca Mountain is presented in Section 10.3.5.2. 
9.3.2 Modeling the Large-Scale Aquifer Pumping and Infiltration Test at INEEL 
Regional and local-scale Large-Scale Aquifer Pumping and Infiltration Test (LPIT) models were 
developed as a goal of this work to address issues related to the fate and transport of 
radionuclides from the RWMC. Modeling activities related to this work were documented in 
Simmons (2002 [157578], SN-LBNL-SCI-186-V1, pp. 1721). A companion study that used 
some of the same data sets to investigate radionuclide retardation is presented in Section 10.3. A 
location map of the RWMC and SDA sites within INEEL is provided in Figure 9.3-2. 
Statistically significant radionuclide concentrations have been measured as deep as 43 m (140 ft) 
and possibly deeper (Becker et al. 1998 [157407], pp. 4-23 to 4-39) beneath the SDA in core 
samples from a sedimentary interbed. This is thought to be a consequence of the SDA having 
been flooded in 1962, 1969, and 1982 (Section 9.3.1.1), when infiltrating water may have 
initiated subsurface migration of the plutonium-contaminated waste. The migration pathway is 
suspected to be vertically downward through the unsaturated basaltic lava flows and then 
laterally on the low permeability (silt, clay) interbeds as ponded-water conditions develop. 
Lateral transport of the radionuclides is suspected to have been enhanced by water infiltrating 
from the spreading area (Figure 9.3-2), causing ponded-water conditions at a scale significantly 
larger than the SDA. The fate and transport of radionuclides at the regional scale involves the 
RWMC, the spreading area, and the inferred SZ pathway potential that radionuclides would take 
from beneath the RWMC to the INEEL boundary (Magnuson and Sondrup 1998 [156431]). 
Migration of radionuclides from the RWMC is dependent upon the mechanisms controlling 
unsaturated flow of infiltrating water. It is also dependent upon the fate and transport of 
radionuclides within the infiltrating water as it flows through the undulating fractured basaltic 
lava flows and sedimetary interbeds beneath the SDA. To address these issues, the LPIT was 
conducted in the summer of 1994 to mimic the intermittent flood events observed at the SDA. 
The test was located approximately 1.43 km south of the RWMC within the same geological 
units (Figure 9.3-2). Details concerning the location, design, implementation, and data sets 
collected during the LPIT are summarized in Dunnivant et al. (1998 [156402]). Magnuson (1995 
[156404]) developed a numerical model to simulate the highly transient water infiltration and 
ponding conditions that existed during the LPIT, as well as transport of the conservative 
selenium (75Se) tracer introduced in the infiltrating water. The modeling approach involved 
determining parameters controlling unsaturated and saturated flow and transport in the fractured 
basalt and sedimentary interbeds. The model was calibrated to ponded water hydrographs and 
75Se breakthrough curves within the ponded water measured during the LPIT. 
The goal of the modeling presented in Section 9.3.2 was to build confidence in the modeling 
approach used for UZ process modeling at Yucca Mountain by comparing simulations to results 
of the LPIT. To achieve the goals of this work, both regional and local-scale LPIT models were 
developed. These models were based upon the work of Magnuson (1995 [156404]) and 
Magnuson and Sondrup (1998 [156431]). The sequence of model development was first to use a 
local-scale LPIT model (Figure 9.3-2) to determine a set of hydrological parameters by 
simultaneous calibration to multiple hydrographs, while using a dual-permeability representation 
of the basalt fracture and matrix continua. These parameters would represent the large-scale 

properties of the lithological units affected by the field-scale LPIT test as used in the dualpermeability 
approach rather than local-scale heterogeneities influencing individual hydrographs. 
Calibration of the model to the LPIT hydrographs and 75Se breakthrough curves is important 
from the perspective of the work conducted in support of the Yucca Mountain repository. This is 
because it tests confidence in the dual-permeability approach, which is also used to represent 
flow and transport processes that are anticipated to occur in the tuff fracture and matrix continua 
at Yucca Mountain. The next step in the sequence of model development was to use hydrological 
parameters obtained from the LPIT calibration to simulate the fate and transport of radionuclides 
from the SDA in the regional model. The dimensions of the regional model are shown in Figure 
9.3-2. Results presented here are limited to the LPIT analysis. 
9.3.3 Conceptual and Numerical Model 
The LPIT consists of a 183 m diameter infiltration pond that was constructed by removing 
surficial soil to build a 1.5 m high earthen berm. The floor of the infiltration pond was highly 
uneven, with approximately 80% of the basin floor consisting of a thin layer of soil overlying the 
basalt, while the remaining 20% consisted of exposed and elevated basalt. The water depth in the 
infiltration pond ranged from 0.3 m to 2 m (Dunnivant et al. 1998 [156402], p. 950). The area 
beneath the infiltration pond that was instrumented and influenced by the LPIT test consists of 
three separate basalt flows (the A, B, and C basalts) with a laterally continuous dense clay 
sedimentary interbed between the B and C basalts. No sedimentary interbed was found between 
the A and B basalt flows at the LPIT site. 
The three-dimensional model (3D) made to represent the region influenced by the LPIT used a 
radial coordinate approach consisting of 20 spokes evenly spaced at 18 degree intervals. The 
centroids of the elements are shown in plan view in Figure 9.3-3a, which shows contours of the 
elevation of the top of the B-C interbed. A radial coordinate approach was used because during 
the LPIT, the infiltrating water was observed to pond on the B-C interbed. It was expected to 
flow radially away from the perimeter of the infiltration pond, with flow controlled by the 
topography of the B-C interbed. Lateral flow caused by ponding on the B-C interbed was 
detected in wells located on the B, C and E rings (Figure 9.3-3a) at several locations (Burgess 
1995 [156401]). The perimeter of the LPIT model was located sufficiently far from the E ring to 
remove any influence of boundary conditions. The surface of the B-C interbed is irregular and is 
crudely approximated by the plan-view discretization shown in Figure 9.3-3a. Note that this 
discretization does not place the centroid of a node at the exact position of a well where a 
specific hydrograph was measured and therefore at the exact elevation of the B-C interbed. This 
approximation was adopted because of constraints in model size required to achieve reasonable 
calibration times. 
Figure 9.3-3b shows a vertical E-W cross-sectional cut through the center of the model. This 
figure shows the undulating thickness of the A and B basalts and the B-C interbed. The centroids 
of the elements are shown in cross section in Figure 9.3-3b, indicating significant mesh 
refinement at the interface between the B basalt and B-C interbed. Grid refinement exercises 
necessitated 0.02 m thick elements at this interface to obtain a convergent solution to the physics 
of water ponding on top of the B-C interbed, while simultaneously imbibing and infiltrating 
through it. In total, 28 elements were used to discretize the domain in the vertical direction. 
Figure 9.3-3b also shows the steady-state water saturations in the fracture continuum calculated 

using a background infiltration rate of 0.01 m/yr (Cecil et al. 1992 [156256], p. 713). Simulation 
results indicate that the silt/clay-like nature of the surficial sediments and B-C interbed retain a 
higher water saturation than the basalt fracture continuum. 
Unsaturated flow was simulated using iTOUGH2 with the EOS9 module, which solves 
Richards equation, while 75Se transport was simulated using the EOS7r module, which handles 
flow less rigorously. The mesh was constructed using a dual-permeability representation for the 
basalt fracture and matrix continua, while the surficial sediments and B-C interbed were 
simulated as a single matrix continuum. The dual-permeability grid is used in an analogous 
manner to that used in simulating site-scale unsaturated flow at Yucca Mountain (Barenblatt et 
al. 1960 [156255]; Pruess and Narasimhan 1985 [101707]; Bandurraga and Bodvarsson 1999 
[103949]). Within the context of the dual-permeability approach, various methods are proposed 
to reduce the interfacial area between the fracture and matrix continua, and hence the degree to 
which they interact. They range in complexity from a constant scaling factor (Bandurraga and 
Bodvarsson 1999 [103949]) to the active fracture model of Liu et al. (1998 [105729]). The 
constant scaling factor approach was adopted for this study to reduce the interfacial area between 
the basalt fracture and matrix continua. This simplification was adopted given the transient 
nature of the LPIT test and because the active fracture model has only been validated for 
steady-state flow within the site-scale Yucca Mountain model. 
The background infiltration rate prescribed to all surface nodes inside the infiltration pond is 
shown on Figure 9.3-4. The rate was calculated as part of a water management system and water 
balance analysis by Starr and Rohe (1995 [156400]). Additional boundary conditions for 
simulating unsaturated flow within the LPIT model include the sides of the model, which were 
assigned to be impermeable boundaries, while the bottom of the model is prescribed as a 
constant-water-pressure condition. For the LPIT transport model, 2 Ci of 75Se was added to the 
infiltration pond water (approximately 31,650 m3) and allowed to infiltrate into the fractured 
basalt from Day 6 to Day 17. The mass fraction of 75Se in the infiltrating water was normalized 
to 1  10-3, given the linear nature of the advection-dispersion equation describing transport of 
the conservative 75Se tracer and the lower limits on the convergence tolerance of the Newton and 
iterative sparse matrix solver schemes (approximately 1  10-6). This scaling is evident in Figure 
9.3-8. 
9.3.4 Hydrological Parameter and Perched-Water Hydrograph Data 
Perched water hydrograph data were collected at 17 locations as presented in Burgess (1995 
[156401]). These were collected in wells located primarily on the A, B, and C rings (see labeled 
symbols in Figure 9.3-3a) and with the screen located at the B basaltB-C interbed interface. 
Hydrographs were not observed at all locations because of difficulties in completing the well at 
this interface. Of the 17 hydrographs, six were selected for the calibration effort. Results of 
numerical tests indicated that inversion using the full 3-D LPIT model containing all 17 
hydrographs was too computationally intensive; therefore, a wedge of nodes on radial spokes of 
34201836 was extracted to calibrate simultaneously to hydrographs in wells B04N11, 
C04C11, B06N11, and C06C11. This set of hydrographs was chosen for calibration because it 
contained two of the three Cring hydrographs and matched B and Cring wells on the same 
radial angle. Although well B05O11 contained an observed hydrograph and was within this 
wedge, it was not used during the inversion in order to act as a control to test the predictive 

capability of the calibrated parameter set. The hydrograph at well B08N11 was also 
independently used as part of a separate calibration to yield a parameter set to test for significant 
differences between calibrated parameters across the region influenced by the LPIT. The six 
hydrographs introduced here are presented in Section 9.3.6, along with calibration results. 
Selenium-75 breakthrough curves within the ponded water were collected at nine locations, as 
presented in Burgess (1995 [156401]). Of the nine breakthrough curves, the B04N11 and 
C04C11 data were selected for calibration because they were within the 34201836 
submodel described above. Furthermore, they have matching B and C ring wells on the same 
radial angle. 
Hydrological parameters relevant to the fractured basalt and sedimentary interbed stratigraphy at 
the LPIT site were identified in a literature survey to constrain the calibration procedure. These 
parameters are listed in Table 9.3-2. Because none of the laboratory analysis was done on cores 
obtained specifically from the LPIT site, only the mean, maximum, and minimum values were 
used to cover the range over which they may be expected to vary for lithological units in the 
LPIT area. The relevant parameters include the basalt matrix continuum permeability, kBM; and 
porosity, fBM (Knutson et al. 1990 [107839], p. 3-93); the B-C interbed matrix continuum 
permeability, kBCM; porosity, fBCM; residual water saturation, SwrBCM; and van Genuchten 
capillary pressure parameters aBCM and mBCM (McElroy and Hubbell 1990 [156433]). The 
properties of the B-C interbed vary significantly because this unit was observed to vary in 
lithology from fine silt to clay (McElroy and Hubbell 1990 [156433]). Fracture spacing for the 
basalt was set to 2.6 m for the entire thickness of the basalt units (Grossenbacher and 
Faybishenko 1997 [107832]). 
All relevant unsaturated flow parameters in the hydrological model are listed in Table 9.3-3. 
Flow parameters shown in Table 9.3-3 but not discussed in this section were not measured from 
cores taken at INEEL in the fractured basaltsedimentary interbed stratigraphy, they were 
instead based on previous INEEL modeling work conducted by Unger et al. (2000 [156398]). 
Selenium-75 transport parameters such as the dispersivity and tortuosity of the basalt and B-C 
interbed were not measured as part of prior laboratory or field investigations. Therefore, it is 
assumed that 75Se does not undergo either molecular or hydrodynamic dispersion over the 60 
day time frame of the LPIT. Hydrodynamic dispersion of the 75Se breakthrough curves will 
occur instead because of imbibition between the basalt fracture and matrix continua. 
9.3.5 Hydrograph Calibration Results 
Initial manual calibration indicated that the six most sensitive parameters controlling the 
calibration of the LPIT model to the hydrographs were the basalt fracturematrix continua 
interfacial area constant-scaling factor ABFM, the basalt fracture continuum permability kBF, the 
basalt matrix continuum permeability kBM, the B-C interbed matrix continuum permeability kBCM, 
and the B-C interbed van Genuchten capillary pressure parameters aBCM and mBCM. The basalt 
fracture and matrix continua porosities were not sensitive parameters controlling calibration. 
This is because imbibition of the infiltration front from the basalt fracture continuum to the 
matrix continuum controlled its downward advection rate rather than the porosity, because of the 
initial dry conditions present at the site. This is shown on Figure 9.3-5, which depicts the water 
saturation in the fracture and matrix continua at 35.5 days. At this point, ponding of water is well 

developed on the B-C interbed and significant quantities of water have been imbibed into the 
matrix continua within the migration path of the infiltration front. 
Parameter estimation during calibration was performed by iTOUGH2 using a Levenberg- 
Marquardt algorithm. Five parameters were included for estimation: kBF, kBM, kBCM, aBCM and 
mBCM. Parameter ABFM was manually adjusted because changes to this parameter required 
rebuilding the mesh. Initial manual adjustment indicated that a value of ABFM = 0.01 provided the 
best fit to the data when using a Brooks-Corey relative permeability curve, which was also 
observed by Unger et al. (2000 [156398], p. 14). A van Genuchten relative permeability curve 
was not used in this study because it caused excessive numerical difficulties when simulating 
ponding because of its steep gradient at water saturations approaching unity. 
Figure 9.3-6 shows simultaneous calibration results to hydrographs B04N11, C04C11, B06N11, 
and C06C11 using the 34201836 submodel extracted from the full 3D LPIT model. This 
model will be referred to hereafter as the 2D model, while the entire LPIT model will be 
referred to as the 3D model. The symbols in Figure 9.3-6 represent water pressure and 
indicate ponded-water elevation within the fracture continuum of the B basalt on top of the B-C 
interbed, where reference atmospheric gasphase pressure is 85 kPa. Calibration was performed 
to a subset of the data points shown in Figure 9.3-5 that were chosen to be more evenly spaced in 
time to prevent biasing the calibration to regions where the data were collected more frequently. 
Calibration parameters were obtained by setting ABFM = 0.01, while the sensitivity of the other 
five calibration parameters to ABFM was determined by doubling it to ABFM = 0.02 and then by 
halving it to ABFM = 0.005. Parameters obtained from the iTOUGH2 calibration are provided in 
Table 9.3-3. 
Comparison of calibrated parameters obtained with ABFM = 0.01 indicates that the estimated 
basalt matrix permeability is almost equal to the mean shown in Table 9.3-2, the B-C interbed 
permeability is just above the minimum observed value, and the B-C interbed van Genuchten 
parameters are also near the mean of the values in Table 9.3-2. Although the data in Table 9.3-2 
were not obtained from the LPIT site, their close correspondence to the estimated parameters 
does build confidence in the ability of the LPIT model to yield a spatially averaged set of 
hydrological parameters to fit the hydrographs. Comparison of calibrated parameters for the 
three different values of ABFM indicates that the basalt fracture continuum permeability remains 
constant at kBF = 3  10-10 m2 and is insensitive to ABFM over the range tested. The basalt matrix 
continuum permeability increases by a factor of 2.51 as ABFM is halved, and decreases by a factor 
of 2.51 as ABFM is doubled. This indicates that basalt fracturematrix imbibition is an important 
process controlling calibration, with ABFM and kBM adjusting proportionately to maintain the same 
amount of flow into the matrix continuum. Interpreting the response of the B-C interbed 
parameters to variations in ABFM is considerably more difficult, except that mBCM reaches (and 
was constrained during calibration by) the maximum observed value for ABFM = 0.005, thereby 
reducing confidence in the physical relevance of the calibration values. In general, given the 
standard deviation of the estimated parameters, no significant difference exists within two 
standard deviations between the three parameter sets listed in Table 9.3-4. 
The full 3D LPIT model was used to determine the effect of having reduced the mesh size to 
the four radial angles of 34201836 to calibrate to the four hydrographs shown in Figure 
9.3-6. The greatest deviation occurs for hydrographs B06N11 and C06C11 because the former is 

situated in a local depression, while the latter is situated on a local mound in the elevation of the 
B-C interbed, as shown on Figure 9.3-3a. Therefore, plan-view grid refinement is necessary to 
obtain increased numerical convergence for parameters listed in Table 9.3-4. The physical 
relevance of the converged parameters would still be limited by the sparse distribution of points 
providing information on the elevation of the B-C interbed. 
The full 3D LPIT model was also used to determine how well the calibrated parameters 
matched the control hydrograph B05O11 that was located within the 2D submodel, as well as 
hydrograph B08N11 that was located outside of the 2D submodel. Figure 9.3-7a shows that the 
3D model successfully modeled the control hydrograph, thus building confidence in the 
physical relevance of the estimated parameters. Figure 9.3-7b shows that when the 3D model is 
used to simulate the B08N11 hydrograph using parameters from Table 9.3-4, the predictive 
capacity of the estimated parameters diminishes. B08N11 is the only hydrograph shown because 
it exhibited the worst fit of the hydrographs located outside of the 2D submodel. An additional 
2D submodel at a radial angle of 288 was extracted from the 3D LPIT model to calibrate to 
the B08N11 data. Calibration was performed with ABFM = 0.01 only; the results are shown on 
Figure 10.3-7b, with the final calibrated parameters listed in Table 9.3-5. Analysis of the 
parameters in Tables 9.3-4 and 9.3-5 indicates that for ABFM = 0.01, the mean estimated values 
for kBF and kBM are significantly different at two standard deviations, while values for kBCM, aBCM 
and mBCM are not. This implies that at the field scale of the LPIT experiment there is greater 
heterogeneity in the hydrological properties of the basalt than of the B-C interbed. 
9.3.6 Selenium (75Se) Calibration Results 
The six parameters identified for the hydrograph calibration were also used to perform a joint 
calibration on the hydrograph and 75Se data for wells B04N11 and C04C11. The objective of this 
calibration effort was to determine whether parameters estimated using both flow and transport 
data are significantly different than those estimated using flow data alone. 
Figure 9.3-8 shows joint hydrograph and 75Se results for observation wells B04N11 and C04C11 
using parameters estimated from the flow calibration (see Table 4, ABFM = 0.01). Two numerical 
difficulties were identified during calibration that prevented completion of the iTOUGH2 
calibration. First, iTOUGH2 with the EOS7r module did not provide a sufficiently robust flow 
simulation in comparison with the EOS9 module while simulating water ponding on the B-C 
interbed. Repeated failure of the Newton iteration caused an excessive number of timesteps, 
ultimately resulting in an accumulation of numerical mass-balance errors within the 75Se mass 
conservation equation. This resulted in nonmonotonic behavior of the 75Se mass-fraction curves 
(as shown on Figure 9.3-8a), making parameter estimation with iTOUGH2 impossible. These 
mass-accumulation errors are not evident in the water mass-conservation equation, as shown by 
Figure 9.3-8b. 
Transport simulation results show that 75Se mass fractions reached source values of 1  10-3, 
which are 15 times greater than peak values observed in the field for B04N11. The tail of the 
simulated 75Se breakthrough declines much more rapidly than observed in the field. This 
discrepancy does not result from the omission of molecular diffusion between and within the 
fracture and matrix continua of the dual-permeability mesh, because upstream-weighting of the 
advective mass-fraction terms in the discretized mass-balance equations in iTOUGH2 will 

introduce significantly more numerical dispersion than would be observed by molecular 
diffusion alone. Any numerical dispersion would be a product of the coarse grid discretization of 
the dual-permeability mesh, as well as the highly advective flow fields simulated during the 
infiltration tests. Given that the general shapes of the simulated breakthrough curves are 
incorrect, it is suggested that while the dual-permeability conceptual model can be used to 
simulate unsaturated flow, it may not adequately capture the physics of conservative transport in 
fractured basalt. Wu et al. (2001 [156399]) suggest that a triple-continuum conceptual model 
involving an interconnected matrix continuum, large-scale fracture continuum, and a small-scale 
fracture continuum may provide a better representation of transport. In this case, it is assumed 
that the small-scale fractures would retain sufficient 75Se to retard its advection, decrease peak 
breakthrough values, and cause significant tailing of the breakthrough curves. Mass transfer of 
75Se from the large-scale fracture continuum into the small-scale fracture continuum would be 
primarily driven by molecular diffusion, which depends upon the concentration gradient of 75Se 
(Liu et al. 2000 [154579]). Resolving the concentration gradient would require multiple 
interconnected nodes to represent the small-scale fracture continuum over a very fine 
(millimeter) scale. Although testing of the triple-continuum conceptual model would only require 
rebuilding a new mesh, successful calibration of this conceptual model in iTOUGH2 is 
contingent upon a more robust flow simulation and removal of the mass-accumulation errors 
seen in the radionuclide conservation equations. 
9.3.7 Conclusions of LPIT Analogue Study 
The study of UZ flow at the RWMC was chosen because INEEL is somewhat analogous to 
Yucca Mountain in hydrogeology. Average precipitation is similar at both sites, although 
infiltration is higher at INEEL. Perched water occurs in the UZ at both sites. Rock at both sites 
consists of a fractured porous media  basalt at INEEL and rhyolitic ash-flow tuff at Yucca 
Mountain. At both sites lateral flow plays a role in diverting flow, whereas the dominant flow 
paths are along fracture pathways. Fracture-filling minerals consist of clays and calcite at both 
sites. Although the two sites differ in significant ways (see Section 10.3.5), their similarities 
made it worthwhile to test modeling approaches of UZ flow (and also radionuclide transport in 
the UZ, as presented in Section 10) at Yucca Mountain with INEEL data. 
Hydrographs of ponded water and 75Se breakthrough curves measured during the LPIT test 
conducted at INEEL were analyzed to determine parameters controlling unsaturated flow and 
transport. Analysis of this data involved building a numerical model using iTOUGH2. The 
numerical model was constructed to conform to the lithological units at the LPIT site, which 
consisted of surficial clay-like sediments underlain by fractured basalt flows (the A, B, and C 
basalts) with a clay-like sedimentary interbed (B-C sediment layer) situated between the B and C 
basalts. The numerical model involved determining parameters controlling unsaturated and 
saturated flow and transport in fractured basalt, using a dual-permeability modeling approach 
that has been extensively employed to simulate flow and transport at Yucca Mountain. 
Six parameters were identified to be most sensitive in controlling the calibration of the LPIT 
model to the observed hydrographs. These included the basalt fracturematrix interfacial area, 
the basalt fracture and matrix continua permeabilities, the B-C interbed permeability, and van 
Genuchten capillary pressure a and m values. Simultaneous calibration to hydrographs B04N11, 
C04C11, B06N11, and C06C11 using iTOUGH2 yielded parameters that were consistent with 

the range in values seen in data obtained from cores drilled near the LPIT site. Joint calibration 
to hydrograph and 75Se data in wells B04N11 and C04C11 was unsuccessful because of 
numerical difficulties. Preliminary results indicated that while the dual-permeability conceptual 
model can be used to simulate unsaturated flow, it did not adequately simulate conservative 
transport in fractured basalt. This is because the matrix continuum needs to be significantly 
refined relative to the dual-permeability approach to resolve molecular diffusion caused by the 
concentration gradient between the fracture and matrix continua. This conclusion is especially 
significant to the site-scale Yucca Mountain model, in which, the dual-permeability approach is 
used extensively to simulate both unsaturated flow and transport in fractured tuff. The dualpermeability 
approach provides conservative estimates of peak concentrations and arrival times 
by underpredicting the mass transfer of conservative (i.e., nonsorbing) tracers from the fracture 
to the matrix continua. 
Parameters estimated by the calibration are inherently spatially averaged over the region sampled 
by the downward-advecting infiltration front and laterally migrating ponded water. This region 
starts from directly beneath the infiltration pond and covers the radial area of the four 
hydrographs. These parameters were able to predict the control hydrograph that was located 
within the spatially averaged region, but were unable to predict hydrograph B08N11, located 
outside of this region. Independent calibration to hydrograph B08N11 indicated that the basalt 
properties showed significantly greater variability than the B-C interbed properties. This implies 
that the field-scale heterogeneity limits the volume to which the spatially averaged basalt 
parameters can be assigned relative to the B-C interbed parameters. This may in part result from 
the fracturedporous dualcontinuum nature of the basalt in comparison to the porous single 
continuum nature of the B-C interbed. 
DRIFT SHADOW ANALOGUES 
The phenomenon of flow diversion around a cavity was investigated for a general homogeneous 
porous medium by Philip et al. (1989 [105743]). The key feature of this phenomenon with 
respect to the transport of dissolved or colloidal material from the drift is that flow velocities in a 
zone beneath the drift are slower than unaffected flow velocities away from the drift (Figure 9.4- 
1). In particular, the flow velocity at the base of the drift is exactly zero. According to this 
conceptual model, the zone beneath the drift was also found to have lower water saturation than 
the undisturbed zone. This region of reduced flow velocity and water saturation beneath the drift 
is known as the drift shadow. 
For a quasi-linear representation of the hydrogeologic properties, Philip et al. (1989 [105743], p. 
18) found that the extent of the drift shadow is a function of a characteristic sorptive length scale 
and the drift radius. The shape of the drift shadow is governed by the ratio of the drift radius to 
the sorptive length scale. The ratio of the drift radius to the sorptive length scale is a measure of 
the relative importance of gravitational forces compared with the capillary forces that define 
flow patterns around the drift. 

9.4.1 Caves 
The drift shadow phenomenon cannot be accurately tested in the underground facility at Yucca 
Mountain because the natural system has been greatly perturbed by the heavy use of construction 
water for dust control and by the large volumes of air exhausted every day. Furthermore, the 
underground facility probably has not yet come to equilibrium with the undisturbed host rock. 
Complicating matters is the fact that detection of a drift shadow zone has never been documented 
for either natural or anthropogenic openingsconceivably, ancient underground tombs and 
features could exist above a drift shadow zone. However, naturally occurring caves provide an 
opportunity to test for a drift shadow zone beneath an opening in the UZ. Limestone caves are 
hydrologically similar to the welded tuffs at Yucca Mountain because, in both cases, flow occurs 
primarily along fractures. Furthermore, caves have had sufficient time to establish hydrologic 
equilibrium. The Carlsbad, New Mexico, region is ideally suited for such a study because the 
large number of caves in the region allows for selection of a cave that closely matches the 
physical characteristics of a potential mined geologic repository. Caves that are known to receive 
direct surficial runoff should be eliminated from consideration. The cave chosen for study should 
be as large as or larger than proposed repository emplacement drift cross sections, currently 
approximately 5 m in diameter. The roof of the cave should be below the zone of surface 
influence, currently estimated as 6 m. Ideally, the cave should be readily accessible to light 
drilling equipment and should be sited so as to accommodate a small meteorological data station. 
The small cave approximately 800 m southeast of Boyds Waterhole and northwest of Carlsbad, 
New Mexico (on the Azotea Peak 7-minute topographic quadrangle map) appears to meet the 
necessary criteria. 
The site should be amenable to standard tracer or infiltration tests. The infiltration tests would 
push the system out of hydrologic equilibrium by applying enough water to the surface above the 
cave to establish dripping into the cave. The tracers would be dyes or biodegradable tracers that 
would be used in an attempt to define flow paths. 
9.4.2 Tunnels or Mines 
Conceivably, an environmental tracer analysis could be used to demonstrate the presence of a 
drift shadow. An old mine in an arid region would be an ideal location, especially if its history 
dated back 100 years or so. Another possibility would be an old railroad tunnel or other tunnel, 
such as the Never-Sweat Tunnel (for ore haulage) at Apache Leap, Arizona, and the nearby 
mine. Chlorine-36 could be used as one possible example of an environmental tracer with a pulse 
input occurring ~50 years ago. If the mine drift is older than 50 years, it is possible that cores 
collected at present adjacent to the drift would contain the bomb-pulse signal, while cores 
collected below the drift would not. In a nearby, much younger drift, it would be expected that 
there would be essentially no difference in 36Cl signal above and below the drift. Chlorine-36 is 
not the only possible tracer that could be used; the ideal tracer would be without background 
from the rock, such as an artificial environmental tracer. 
9.5 CONCLUSIONS 
Hydrographs of ponded water and 75Se breakthrough curves measured during the LPIT test 
conducted at INEEL were analyzed to determine parameters controlling unsaturated flow and 

transport. Analysis of this data involved building a numerical model using iTOUGH2 in a dualpermeability 
modeling approach, an approach that has been extensively used to simulate flow 
and transport at Yucca Mountain. 
Six parameters were identified to be most sensitive in controlling the calibration of the LPIT 
model of unsaturated flow in fractured basalt. These included the basalt fracturematrix 
interfacial area, the basalt fracture and matrix continua permeabilities, the B-C interbed 
permeability, and van Genuchten capillary pressure a and m values. Simultaneous calibration to 
hydrographs using iTOUGH2 yielded parameters that were consistent with the range in values 
seen in data obtained from cores drilled near the LPIT site. Preliminary results indicated that 
while the dual-permeability conceptual model can be used to simulate unsaturated flow, it may 
not adequately capture the physics of conservative transport in fractured basalt. This conclusion 
is relevant to the site-scale Yucca Mountain model, in which the dual-permeability approach is 
used extensively to simulate both unsaturated flow and transport in fractured tuff. 
Parameters estimated by the calibration are inherently spatially averaged over the region sampled 
by the downward-advecting infiltration front and laterally migrating ponded water. The region 
starts from directly beneath the infiltration pond and covers the radial area of the four 
hydrographs. The basalt properties showed significantly greater variability than the B-C interbed 
properties. This implies that the field-scale heterogeneity limits the volume to which the spatially 
averaged basalt parameters can be attributed relative to the B-C interbed parameters. This may in 
part be due to the fractured-porous dual-continuum nature of the basalt in comparison to the 
porous singlecontinuum nature of the B-C interbed. 
Finally, natural caves and man-made openings such as mines and tunnels may be suitable 
locations for testing the drift shadow concept, particularly if those sites have existed long enough 
to establish hydrologic equilibrium. 

Table 9.3-1. Distribution Coefficient (Kd) Values for Sorption of Contaminants on INEEL Sediments 
Kd Values (mL/g) and Range 
Element 
Surficial Sediments 
Interbeds 
Basalt 
Am 
No data 
450 (450 to 1,100) 
70 (70 to 280) 
Co 
No data 
1,148 (1,148 to 3,912) 
11 (11 to 54) 
Cs* 
950 (589 to 1,253) 
(75 to 225) 
2,228 (2,228 to 3,255) 
39 (39 to 44) 
Pu 
7,800 (7,800 to 22,000) 
5,100 (5,100 to 7,900) 
70 (70 to 130) 
Sr* 
24 (23 to 26) 
(8.3 to 16.6) 
50 (35 to 52) 
42 (42 to 63) 
155 (110 to 186) 
6 (6 to 13) 
(1.1 to 2.7) 
Tc 
0 
0 
0 
U 
No data 
3.4 (3.4 to 9) 
0.2 (0.2 to 5.2) 
Hg 
972 (236 to 1,912) 
176 (72 to 673) 
(9.2 to 87) 
NOTE: *Different Kd values for Cs and Sr are from different authors cited by Dicke (1997 [157410], Table 1). 
Source: Dicke 1997 [157410], Table 1. 
Table 9.3-2. Basalt and B-C Interbed Parameters Collected by Laboratory Analysis of Core Samples 
Property 
Samples 
Mean 
Maximum 
Minimum 
kBM [m2] 
43 
2.2410-15 
9.4810-14 
110-16 
fBM [] 
50 
19.2 
43.2 
5.2 
kBCM [m2] 
15 
4.2110-14 
6.8610-12 
1.1510-17 
fBM [] 
15 
0.530 
0.629 
0.424 
SwrBCM [] 
15 
0.183 
0.376 
0.038 
aBCM [Pa-1] 
15 
7.9510-5 
5.02510-4 
1.93810-6 
mBCM [] 
15 
0.4 
0.86 
0.23 
geometric mean 
arithmetic mean 
Source: Simmons 2002 [157578], SN-LBNL-SCI-186-V1, p. 55. 

Table 9.3-3. Basalt and B-C Interbed Parameters Used in the LPIT Model 
Value 
Parameter 
basalt fracture 
basalt matrix 
B-C interbed 
kx = ky = kz [m2] 
From calibration 
From calibration 
From calibration 
f [] 
0.01 
19.2 
0.53 
Swr [] 
0.01 
0.1 
0.183 
a [Pa-1] 
510-3 
510-4 
From calibration 
m [] 
0.5 
0.25 
From calibration 
Source: Simmons 2002 [157578], SN-LBNL-SCI-186-V1, p. 55. 
Table 9.3-4. Parameters Estimated during Calibration to Hydrographs B04N11, C04C11, B06N11 and 
C06C11 
ABFM = 0.01 
ABFM = 0.005 
ABFM = 0.02 
Param. 
Mean 
std. dev. 
Mean 
std. dev. 
Mean 
Std. dev. 
kBF 
3.2710-10 
0.0701 
3.1310-10 
0.0553 
3.4410-10 
0.0759 
kBM 
2.5110-15 
0.395 
6.3110-15 
0.197 
110-15 
0.381 
kBCM 
5.0110-17 
1.51 
6.3110-17 
0.538 
1.2610-16 
0.848 
aBCM 
110-4 
1.23 
4.0710-6 
0.465 
110-4 
0.852 
mBCM 
0.28 
0.341 
0.86 
0.718 
0.67 
1.08 
mean permeability values are in [m2] while standard deviation is in [log10 m2] 
mean aBCM values are in [Pa-1] while standard deviation is in [log10 Pa-1] 
Source: Simmons 2002 [157578], SN-LBNL-SCI-186-V1, p. 56. 
Table 9.3-5. Parameters Estimated during Calibration to Hydrograph B08N11 
Parameter 
Mean 
std. dev. 
kBF 
7.0510-10 [m2] 
0.0553 [log10 m2] 
kBM 
7.9410-14 [m2] 
0.162 [log10 m2] 
kBCM 
2.5110-16 [m2] 
0.342 [log10 m2] 
aBCM 
6.3110-5 [Pa-1] 
0.690 [log10 Pa-1] 
mBCM 
0.48 
0.527 
Source: Simmons 2002 [157578], SN-LBNL-SCI-186-V1, p. 56. 

Source: Simmons 2002 [157578], SN-LBNL-SCI-108-V2, p. 8 
Figure 9.3-1. Schematic Stratigraphic Sequence Illustrating 
the Relationship between Basalt Flows and Sediment Layers 
75000 76000 77000 78000 79000 80000 81000 82000 83000 84000 85000 
196000 
197000 
198000 
199000 
200000 
201000 
202000 
203000 
204000 
205000 
206000 
207000 
1580 
1576 
1572 
1568 
1564 
1560 
1556 
1552 
1548 
1544 
1540 
1536 
1532 
1528 
1524 
1520 
Elevation 
(m) 
Easting (m) 
Northing (m) 
RWMC (and SDA) 
perimeter of 
LPIT model 
Big Lost River 
Spreading 
Areas 
INEEL boundary 
Source: Simmons 2002 [157578], SN-LBNL-SCI-186-V1, p. 58. 
Figure 9.3-2. Plan View of Regional Model with Contours of the Ground Surface Elevation 

Northing (m) 
81400 81600 81800 82000 82200 82400 82600 
201400 
201600 
201800 
202000 
202200 
202400 
202600 
1496 
1495.5 
1495 
1494.5 
1494 
1493.5 
1493 
1492.5 
1492 
1491.5 
1491 
1490.5 
1490 
1489.5 
1489 
1488.5 
BC Interbed 
Elevation 
(m) 
Easting (m) 
perimeter of 
LPIT model 
E-ring 
C-ring 
B-ring 
perimeter of 
infiltration pond 
B08N11 
B06N11 
C06C11 
B04N11 
C04C11 
B05O11 
(b) 
-500 -400 -300 -200 -100 0 100 200 300 400 500 
1470 
1480 
1490 
1500 
1510 
1520 
1530 
1540 
1550 
1
0.95 
0.9 
0.85 
0.8 
0.75 
0.7 
0.65 
0.6 
0.55 
0.5 
0.45 
0.4 
0.35 
0.3 
0.25 
0.2 
0.15 
0.1 
0.05 
0 
Radius (m) 
Elevation (m) 
Swf 
B basalt 
A basalt 
surficial 
sediments 
BC interbed 
C basalt 
infiltration 
pond 
NOTE: In (a), the centroids of the elements are indicated as black dots and the 
wells by red dots 
Source: Simmons 2002 [157578], SN-LBNL-SCI-186-V1, p. 59 
Figure 9.3-3. (a) Top of B-C Interbed Elevation with Centroids of Elements in Plan View As Well As the 
Location of All Hydrographs Used in this Analysis. (b) East-West Cross-Sectional View Showing the 
Steady-State Water Saturation in the Fracture Continuum 

0 10 20 30 40 50 60 
0 
0.01 
0.02 
0.03 
0.04 
0.05 
0.06 
0.07 
0.08 
0.09 
0.1 
0.11 
0.12 
0.13 
0.14 
Time (days) 
Infiltration Rate (m/day) 
Source: Simmons 2002 [157578], SN-LBNL-SCI-186-V1, p. 60. 
Figure 9.3-4. Infiltration Rate Observed by Starr and Rohe (1995 [156400]) 
during the LPIT Using a Water Balance Analysis 

(a) 
-500 -400 -300 -200 -100 0 100 200 300 400 500 
1470 
1480 
1490 
1500 
1510 
1520 
1530 
1540 
1550 
1
0.95 
0.9 
0.85 
0.8 
0.75 
0.7 
0.65 
0.6 
0.55 
0.5 
0.45 
0.4 
0.35 
0.3 
0.25 
0.2 
0.15 
0.1 
0.05 
0 
Radius (m) 
Elevation (m) 
Swf 
B basalt 
A basalt 
surficial 
sediments 
BC interbed 
C basalt 
B04N11 
C04C11 
(b) 
-500 -400 -300 -200 -100 0 100 200 300 400 500 
1470 
1480 
1490 
1500 
1510 
1520 
1530 
1540 
1550 
1
0.95 
0.9 
0.85 
0.8 
0.75 
0.7 
0.65 
0.6 
0.55 
0.5 
0.45 
0.4 
0.35 
0.3 
Radius (m) Elevation (m) 
Swm 
B basalt 
A basalt 
surficial 
sediments 
BC interbed 
C basalt 
B04N11 
C04C11 
Source: Simmons 2002 [157578], SN-LBNL-SCI-186-V1, p. 61. 
Figure 9.3-5. Water Saturation in the (a) Fracture and 
(b) Matrix Continua at 35.5 Days after the Start of the LPIT 

0 10 20 30 40 50 60 
85000 
86000 
87000 
88000 
89000 
90000 
91000 
92000 
93000 
94000 
95000 
96000 
97000 
98000 
99000 
100000 
101000 
field 
model 0.01 3D 
model 0.005 3D 
model 0.02 3D 
model 0.01 2D 
model 0.005 2D 
model 0.02 2D 
Water Pressure (Pa) 
B04N11 
(a) 
0 10 20 30 40 50 60 
85000 
86000 
87000 
88000 
89000 
90000 
91000 
92000 
93000 
C04C11 
(b) 
0 10 20 30 40 50 60 
85000 
86000 
87000 
88000 
89000 
90000 
Water Pressure (Pa) 
Time (days) 
B06N11 
(c) 
0 10 20 30 40 50 60 
85000 
86000 
87000 
88000 
89000 
90000 
91000 
92000 
93000 
Time (days) 
C06C11 
(d) 
NOTE: Symbols represent field data with reference atmospheric gas phase pressure equal to 85 kPa. 
Lines represent calibration results using the 2D submodel and the full 3D LPIT model with 
varying ABFM values (0.01, 0.005, 0.02). 
Source: Simmons 2002 [157578], SN-LBNL-SCI-186-V1, p. 62. 
Figure 9.3-6. Ponded Water Hydrographs in Wells B04N11, C04C11, B06N11 and C06C11 

0 10 20 30 40 50 60 
85000 
86000 
87000 
88000 
89000 
90000 
91000 
92000 
93000 
94000 
95000 
96000 
97000 
98000 
99000 
100000 
101000 
field 
model 0.01 3D 
model 0.005 3D 
model 0.02 3D 
Water Pressure (Pa) 
B05O11 
(a) 
Time (days) 
0 10 20 30 40 50 60 
85000 
86000 
87000 
88000 
89000 
90000 
91000 
92000 
93000 
94000 
95000 
96000 
97000 
98000 
99000 
100000 
101000 
102000 
103000 
field 
model 0.01 3D 
model 0.005 3D 
model 0.02 3D 
model 0.01 2D 
B08N11 
(b) 
Time (days) 
NOTE: Symbols represent hydrograph data while lines represent model results. 
Source: Simmons 2002 [157578], SN-LBNL-SCI-186-V1, p. 63. 
Figure 9.3-7. (a) Predictive Model Results for Control Hydrograph B05O11 and (b) Calibration Model 
Results for Hydrograph B08N11 
0 10 20 30 40 50 60 
85000 
86000 
87000 
88000 
89000 
90000 
91000 
92000 
93000 
94000 
95000 
96000 
97000 
98000 
99000 
100000 
101000 
model B04N11 
model C04C11 
field B04N11 
field C04C11 
Time (days) 
(b) 
0 10 20 30 40 50 60 
10-8 
10-7 
10-6 
10-5 
10-4 
10-3 
model B04N11 
model C04C11 
field B04C11 
field C04C11 
Time (days) 
75Se Mass Fraction 
Water Pressure (Pa) 
(a) 
Source: Simmons 2002 [157578], SN-LBNL-SCI-186-V1, p. 63. 
Figure 9.3-8. Joint (a) 75Se Breakthrough and (b) Hydrograph Calibration Results for Wells B04N11 
and C04C11 

Source: DOE 2001 [153849], Figure 4-116. 
Figure 9.4-1. Schematic Diagram of Diffusion Barriers in Invert and Drift Shadow Zone 

11. ANALOGUES TO THERMALLY COUPLED PROCESSES 
11.1 INTRODUCTION 
Numerous igneous-intrusion contact zones have been examined with the objective of 
understanding chemical reactions and migration of elements away from the heated contact zone, 
as well as understanding thermal-hydrologic-chemical (THC) effects. A number of these studies 
are described in CRWMS M&O (2000 [141407]; 2000 [151945], Section 13) and BSC (2004 
[168845], Section 4.2.3.5), as summarized by the following. 
The effects of shallow (<500 m) magmatic intrusions into unsaturated host rocks can be quite 
different from effects associated with deeper hydrothermal systems. Deeper, saturated 
hydrothermal systems may display evidence of formation of a large-scale hydrothermal cell 
(Brookins 1986 [109877], p. 337). In contrast, both the Banco Bonito study (Stockman et al. 
1994 [117820], p. 88) and the Grants Ridge basalt intrusion study (WoldeGabriel et al. 1999 
[110071], p. 409) indicate that the effects of high-temperature (~850oC; Stockman et al. 1994 
[117820], p. 88) intrusions into these unsaturated environments appear to have been slight, to 
have been limited to within 10 m or so of the contacts, and to show no evidence of fluid-driven 
convective heat transfer or pervasive hydrothermal alteration of the country rock. These field 
studies, along with the Paiute Ridge field studies (Section 11.4), provide limiting hightemperature-
case natural analogues for evaluating THC processes resulting from the heat 
released by the decay of radioactive waste in an unsaturated environment. 
A good analogy for understanding future water-rock interactions at the mountain scale is the 
fossil hydrothermal system at Yucca Mountain itself. Most zeolitic alteration occurred 13 to 
11.6 Ma, at about the same time as tuff emplacement (Bish and Aronson 1993 [100006], p. 148). 
After formation of the major zeolitic horizons, deep-seated hydrothermal activity persisted until 
about 10 Ma. This activity was evidently limited to temperatures of 90100oC because at 
prolonged exposure to temperatures greater than 90oC, the sorptive zeolites clinoptilolite and 
mordenite are altered to the nonsorptive minerals analcime plus quartz and/or calcite, and this 
transformation did not occur. 
Section 11 reports analyses conducted since CRWMS M&O 2000 [141407] of THC and 
thermal-hydrologic-mechanical (THM) natural analogue studies. Section 11.2 presents the 
results of an extensive survey of geothermal literature for the purpose of obtaining insights from 
coupled processes operating in geothermal fields. Section 11.3 then provides a detailed 
examination of THC processes relevant to the Yucca Mountain drift-scale system, observed at 
the Yellowstone, Wyoming geothermal field. Section 11.4 presents results of a field 
investigation and modeling study of evidence left in a fossil hydrothermal system at Paiute 
Ridge, Nevada. Next, examples are given in Section 11.5 of evidence for THC effects on 
transport. Section 11.6 reports THM effects to a potential repository from a number of settings 
with analogous conditions. Finally, Section 11.7 summarizes what can be learned about THC 
and THM coupled processes relevant to a potential high-level waste repository at Yucca 
Mountain. Information found in Sections 11.2 through 11.5 may help to support arguments 
associated with KTI KUZ0407 listed in Table 1-1. 

11.2 GEOTHERMAL ANALOGUES TO YUCCA MOUNTAIN THERMALHYDROLOGIC-
CHEMICAL PROCESSES 
11.2.1 Objectives 
The goal of Section 11.2 is to demonstrate the utility of geothermal systems as natural analogues 
for processes that are expected to occur in the Yucca Mountain repository. The primary 
objective of Section 11.2 is to use geothermal systems as natural analogues for illustrating 
coupled processes that impact permeability, fluid flow, and chemical transport. The introduction 
to this section notes some of the key THC processes observed in geothermal systems and how 
these processes might impact the Yucca Mountain repository. A summary of key components of 
geothermal systems is then presented, followed by a description of the Yucca Mountain 
repository and a discussion of limitations of geothermal analogues for the Yucca Mountain 
system. The main body of this report consists of descriptions of geothermal analogues for each 
of the key THC processes identified. This is followed by a discussion of how these processes 
could impact the total site performance. Finally, suggestions are made for additional work that 
would further extend the use of geothermal systems in the validation and confirmation of Yucca 
Mountain models. The initial stages of a literature survey identified the Yellowstone geothermal 
system as particularly relevant for the Yucca Mountain system. Detailed analysis of core 
samples from Yellowstone was conducted to supplement previous studies of the Yellowstone 
geothermal system. The results of this work are described in detail in Section 11.3 of this report. 
11.2.2 Introduction 
Geothermal systems can be used as a natural laboratory for examining many of the coupled THC 
processes expected for the nuclear waste repository at Yucca Mountain (Simmons and 
Bodvarsson 1997 [126511]; CRWMS M&O 2000 [141407]). Key processes that are expected to 
occur in the high-level nuclear waste repository at Yucca Mountain, such as boiling and 
condensation and mineral dissolution and precipitation, and their effects on permeability, fluid 
flow, and radionuclide transport, can be observed in many geothermal systems. Prior use of 
geothermal systems as natural analogues has focused on the verification of geochemical models 
(e.g., Meijer 1987 [101345]; Apps 1995 [154615]; Bruton et al. 1995 [117033]). However, 
active and fossil geothermal systems can also yield important insights into the consequences of 
processes such as boiling, condensation, fluid mixing, and water-rock interaction associated with 
fluid flow in matrix and fractures (Figure 11.2-1). These systems allow observation of the 
effects of processes over much longer time scales than are possible in laboratory or field testing, 
and provide a benchmark for coupled process modeling. Characterization of the effects of waterrock 
interaction (such as mineral precipitation and dissolution) on matrix and fracture 
permeability in geothermal systems can then be used to estimate potential changes in fluid flow 
resulting from the thermal impact of storing high-level nuclear wastes in fractured ash flow tuffs. 
This study builds upon an earlier review of geothermal systems as natural analogues (Simmons 
and Bodvarsson 1997 [126511]; CRWMS M&O 2000 [141407]). This study expands the scope 
of the earlier review by including additional THC processes that are observed in geothermal 
systems and incorporates the results of new geothermal studies as part of a literature review. 
Because no single geothermal analogue is suitable for all elements of Yucca Mountain, the 

geothermal analogues are used to evaluate the effects of individual THC processes, with multiple 
geothermal examples examined for each process of interest. 
11.2.3 Similarities between Geothermal Systems and Yucca Mountain 
There are many similarities between geothermal systems and an anthropogenic hydrothermal 
system that would be created by the emplacement of high-level nuclear waste. For most 
geothermal systems, intrusion of magma at shallow crustal levels results in high heat flow and 
the formation of a convective hydrothermal system with associated water-rock interaction. In the 
anthropogenic system, heat-generating nuclear waste would induce changes in the ambient 
system. Both types of systems are subjected to coupled THC processes (Table 11.2-1) such as 
conductive and advective heating, fluid flow and chemical transport through matrix and 
fractures, boiling and condensation, and mineral dissolution and precipitation. These processes 
can result in important changes in the fluid flow properties of the rocks surrounding the heat 
source over time. 
The use of geothermal systems as natural analogues for THC processes is most applicable for the 
higher temperature (above boiling) operating mode, because many of the processes mentioned in 
Table 11.2-1 would have little effect on a cooler, sub-boiling repository. These processes will 
have a greater impact in the near-field area, where the effects of heating (and associated THC 
processes) are expected to be most pronounced. For all cases, the magnitude of the effects of 
many THC processes (such as boiling, condensation, mineral dissolution, and precipitation) is 
envisioned to be significantly reduced at Yucca Mountain as a result of the much lower 
anticipated fluid and thermal flux rates than those observed in active geothermal systems. Key 
differences between geothermal systems and Yucca Mountain are described in Section 11.2.7. 
However, geothermal systems provide well-constrained examples of how THC processes can 
modify important hydrogeologic properties (such as porosity, permeability, and sorptive 
capacity) that would affect the total system performance of a geologic high-level radioactive 
waste repository. 
11.2.4 Key Physical Components of Geothermal Systems 
Prior to providing detailed evaluation of geothermal systems of natural analogues, it is 
worthwhile to examine the key components of these systems. While geothermal systems are 
found in a variety of geologic and tectonic environments and have many different characteristics, 
they all share a number of common traits. These include: (1) heat source, (2) fluids, (3), 
permeable flow paths, and (4) impermeable boundaries. Another important feature present in 
many vapor-dominated geothermal systems is a heat pipe, consisting of a boiling zone and 
condensation zone. Each of these features is discussed below. 
11.2.4.1 Heat Source 
Most active geothermal systems have magmatic heat sources, consisting of shallow intrusions 
that provide a high-level heat source for periods ranging from 100,000 to over 1,000,000 years. 
These intrusive bodies also supply magmatic components (such as water, CO2, SO2, and HCl) 
that often control the chemistry of the reservoir fluids. For example, the granitic pluton 
underlying The Geysers geothermal field in California was emplaced around 1.2 Ma (Dalrymple 

et al. 1999 [156374], pp. 293297), serving as a long-lived heat source for the still-active 
geothermal field. The Krafla and Nmafjall geothermal fields, located along the Mid-Atlantic 
Rift Zone in Iceland, are much younger systems, where recent ongoing volcanic activity (1975 
1984) led to the injection of magma into an existing geothermal well bore (Larsen et al. 1979 
[155885]). 
11.2.4.2 Fluids 
Geothermal energy is extracted from local thermal anomalies in the earths crust through the 
withdrawal of heated fluids. These fluids have a number of origins: connate (formation) waters, 
surface (meteoric) waters, juvenile (magmatic) waters, and seawater. The relative amounts of 
these fluids depend greatly on the geology and tectonic environment, the groundwater hydrology, 
the local climate, and the size and composition of the cooling and degassing intrusive heat 
source. The origin and abundance of these fluid types in geothermal systems can be determined 
through isotopic and geochemical study of fluid compositions (e.g., Giggenbach 1997 [156338]; 
Kennedy and Truesdell 1996 [156339]; Arnrsson 1995 [156321]). 
11.2.4.3 Permeable Flow Paths 
The development of a convecting geothermal reservoir (and the successful exploitation of such a 
resource) depends on the presence of high-permeability pathways. Many geothermal reservoirs 
are hosted by rocks with low matrix permeabilities, resulting from either intrinsically low 
permeabilities (i.e., intrusive igneous rocks and welded ash flow tuffs) or from hydrothermal 
alteration. The presence of a high-permeability fracture network in many geothermal systems 
allows for the heated fluids to flow convectively within the reservoir. Such permeable fracture 
networks may be generated by faulting occurring within tectonically active areas (Moore et al. 
2001 [156320]; Forster et al. 1997 [156355]). 
11.2.4.4. Impermeable Seals 
The longevity of a geothermal resource depends on the presence of an impermeable cap above 
the reservoir. Without such a cap, heated fluids would buoyantly rise to the surface, rapidly 
dissipating the heat of the source. This impermeable barrier may result from a pre-existing lowpermeability 
formation, but often develops as a result of extensive argillic alteration occurring at 
temperatures of 100200C. Lateral permeability barriers along the margins of geothermal 
systems can form by precipitation of retrograde solubility minerals, such as anhydrite and calcite, 
from descending (and heating) fluids along the margins of a geothermal system (Allis and Moore 
2000 [156316], p. 215). 
11.2.4.5 Heat Pipes 
Geothermal heat pipes have been described for a number of vapor-dominated geothermal 
systems (Ingebritsen and Sorey 1988 [137537]; Allis and Moore 2000 [156316]). In a 
geothermal heat pipe (Figure 11.2-1), water boils at the heated (lower) end, and water vapor 
migrates to the cooler region where it condenses and the heat of vaporization is released. The 
condensed water then flows back to the heated end by gravity or capillary forces. The region 
within the heat pipe will be at a nearly uniform temperature near the boiling point of water. The 
condensate water will be undersaturated with respect to the host rock minerals and will begin to 

dissolve constituents from the rock and gases locally present. Some of the water containing the 
dissolved constituents will flow through the fractures back down towards the heat source. Water 
flowing back towards the heat source will boil again, precipitating the formerly dissolved solids. 
The repeated dissolution and precipitation will affect fracture permeability by locally widening 
apertures where dissolution takes place, or narrowing apertures where precipitation occurs. 
The heat-pipe features observed in geothermal systems have also been demonstrated in smallerscale 
laboratory experiments. A heat-pipe reactor was built using tuff chips from Yucca 
Mountain and operated for 30 days (Rimstidt et al. 1989 [142190]). In the top region 
(condensation zone), etching and dissolution were observed. In the center region, few 
indications of dissolution or precipitation were observed. In the bottom region, extensive 
precipitation was observed with silica, iron oxyhydroxides, stilbite, and possibly clays forming. 
A layer of rock grains tightly cemented with amorphous silica formed at the face of the heater; 
this mineralization would result in reduced permeability. Similar heat-pipe features were also 
observed in the column tests reported in Lowry (2001 [157900]). 
11.2.5 Characteristics of the Yucca Mountain Repository 
The Yucca Mountain nuclear waste repository is planned to be sited within a section of crystalpoor, 
devitrified, moderately to densely welded Topopah Spring tuff that forms part of a 1,000-m 
(3,300-ft) thick section of 1114 Ma ash flow tuffs at Yucca Mountain (CRWMS M&O 1997 
[100223], Figure 35). The repository horizon is overlain by 300 m (980 ft) of nonwelded to 
densely welded tuff, and underlain by a sequence of nonwelded to densely welded Miocene ash 
flow tuffs, older Tertiary volcanic and sedimentary rocks, and Paleozoic dolomites. The 
repository would be located within the unsaturated zone (UZ), 350 m (1,150 ft) above the 
regional water table (Figure 11.2- 2). The repository is located in fractured unsaturated host rock 
with very low matrix permeability. The combination of low matrix permeability and unsaturated 
rock helps keep water from waste packages, thus retarding unwanted processes such as corrosion 
of the waste packages, dissolution of the waste materials, and transport of radionuclides to local 
aquifers. Fluid flow along high-permeability fractures may, however, result in seepage. 
The higher-temperature operating mode (BSC 2001 [155950], Section 2.3) consists of a drift 
spacing of 81 m (266 ft), with drip shields, line load waste packaging, and 50 years of drift 
ventilation after the waste has been emplaced. These design attributes (see also Section 2 of this 
report) are used to minimize seepage onto the waste containers, limit peak temperatures in the 
drifts, and reduce the likelihood of the development of coalescing boiling zones, thus permitting 
drainage to occur in the pillar regions between the drifts. For the higher-temperature operating 
mode, maximum temperatures of around 120C are predicted for the drift wall (BSC 2001 
[155950], Section 4.3.5.3.3), with temperatures greater than 100C predicted to persist in the 
waste package and near-field for 1,0002,000 years. Other design possibilities also under 
consideration include a lower-temperature operating mode in which the maximum temperature at 
the drift wall will never exceed 85C (BSC 2001 [155950], Section 3.2.5). 
The near-field repository environment is predicted to undergo two distinct phases resulting from 
the thermal loading: dryout and rewetting. Dryout is predicted to occur as the waste packages 
transfer their heat to the surrounding environment. The size of the dryout zone will vary with 
time and may extend up to 13 m (43 ft) away from the drift walls (BSC 2004 [167974], Sections 

6.5.5.1 and 6.8.5.2). During the dryout phase, liquid water will be converted to water vapor, 
which will effectively displace air from this zone. This is important because the oxygen 
necessary for many corrosion reactions will be present only in low concentrations. As the heat 
output from the waste package diminishes with time, dryout zones are predicted to gradually 
undergo rewetting from reflux of CO2-replenished condensate and ambient percolation. The 
rewetting will be accompanied by an influx of air back into the near-drift environment as 
temperatures drop below the local boiling point and slowly approach ambient (pre-repository) 
thermal conditions (BSC 2004 [167974], Section 6.8.5). 
Subsurface fluid flow for the Yucca Mountain area is controlled by the permeability and 
unsaturated hydraulic properties of the Miocene ash flow tuff sequence. Densely welded 
sections of the tuff have very low matrix permeabilities, and fluid flow through these sections is 
controlled by faults and fractures. Nonwelded tuffs have significantly higher matrix 
permeabilities and fewer fractures, and thus matrix flow appears to be the dominant process in 
these sections. These differences in matrix and fracture permeability as a function of welding 
(Figure 11.2-3) are characteristic of ash flow tuff deposits (Winograd 1971 [156254]). The 
potential repository is located within a densely welded devitrified tuff (Figure 11.2-2), and thus 
bulk permeability for this horizon is controlled by fractures. 
Fracture permeability depends on a variety of fracture characteristics, including fracture 
orientations relative to the regional stress field, fracture density and spacing, fracture apertures, 
and the presence or absence of mineralization within the fractures. Field permeability 
measurements have been made at the Yucca Mountain Exploratory Studies Facility (ESF) to 
evaluate the variability of permeability and identify controlling factors. The matrix permeability 
of the welded Topopah Spring tuff (TSw) is 3 to 6 orders of magnitude lower than the fracture 
permeability (LeCain 1997 [100153], pp. 2829), so fluid flow within this formation should be 
highly focused along fractures. 
11.2.6 Time Scales of Geothermal Processes 
Time scales of processes expected to occur in a geologic nuclear waste repository are compared 
with processes that occur in geothermal systems shown in Table 11.2-2. Because of these very 
long and variable time scales, it is not possible to create a scale model of a nuclear waste 
repository, study all of these processes for a short while, and then extend this knowledge to real 
repository future behavior. Laboratory and field-scale studies have been conducted and others 
are currently underway to study some of these processes for the purpose of model validation. 
Computer-based numerical modeling is being used to interpret and extend these results within a 
framework of well-understood physical laws and data. The same processes expected to occur at 
a geologic high-level nuclear waste repository at Yucca Mountain have been occurring over the 
long-term in geothermal systems, making the study of geothermal systems highly relevant to the 
long-term understanding of possible repository behavior. 
11.2.7 Limitations of Geothermal Analogues 
It is important to note several important differences between most geothermal analogues and the 
proposed Yucca Mountain repository: 

The Yucca Mountain repository is located within unsaturated rocks, while most 
geothermal systems have saturated conditions. While the repository may develop locally 
saturated areas (such as the condensation zone), this difference should result in reduced 
water-rock interaction for the thermally loaded repository system. Convective liquid 
flow will not develop under unsaturated conditions, and thus thermal and fluid fluxes for 
the Yucca Mountain system will be significantly lower than those found in hightemperature 
geothermal systems. Advective transport will still occur within the fracture 
network, and thus chemical transport rates could be fairly rapid along the fast flow paths 
within the UZ at Yucca Mountain. Several natural analogues that have experienced 
elevated temperatures under unsaturated conditions (Banco Bonito, New Mexico, and 
Paiute Ridge intrusive complex, Nevada) exhibit very little hydrothermal alteration 
resulting from the heat pulse event (Stockman et al. 1994 [117820]; Lichtner et al. 1999 
[121006]; and Section 11.4 of this report). 
Liquid-dominated geothermal systems have increasing hydrostatic pressures with depth, 
reflecting the presence of a hydrostatic column. Boiling within a geothermal system at 
depth thus occurs at progressively higher temperatures (following the boiling point-depth 
curve). Because Yucca Mountain is an unsaturated system, fluid pressures will typically 
not exceed atmospheric pressure, and thus boiling should occur at temperatures around 
96C throughout the system. 
The higher-temperature operating mode for the Yucca Mountain repository is predicted 
to have an areally restricted and short-lived (1,0002,000 yrs) higher temperature 
(>100C) pulse, thus limiting the time when boiling and condensation processes could 
occur. In addition, because of the unsaturated nature of the Yucca Mountain system, 
dryout zones should develop around the high-temperature repository drift areas, also 
serving to reduce the potential impact of water-rock interaction. 
For the lower-temperature operating mode, drift-wall temperatures will never exceed 
boiling point values, and thus precipitation of dissolved species resulting from boiling 
will not occur. Some increase in the concentration of dissolved species may result from 
evaporation in this case. The lower predicted temperatures in this operating mode will 
also result in less extensive water-rock interaction, with reduced amounts of mineral 
alteration, dissolution, and precipitation. 
Speciation and transport of dissolved species may be affected by the redox state of the 
system. Geothermal systems are typically somewhat reducing in nature (as evidenced by 
the presence of H2S rather than SO2 in most geothermal fumarolic gases), whereas the 
Yucca Mountain system is expected to be more oxidizing (owing to the presence of 
atmospheric oxygen in the gas phase). This difference in oxidation state could affect the 
transport and precipitation of chemical components with multiple oxidation states (such 
as Fe2+/Fe3+ and U4+/U6+), but should not significantly impact the behavior of important 
sealing species such as silica. 
Gas compositions of geothermal systems differ significantly from that predicted for 
Yucca Mountain, which lacks a magmatic fluid component. While both systems will 
contain CO2 and air, most geothermal systems also contain significant amounts of sulfur

bearing gases (typically H2S) that can lead to the development of acidic fluid 
compositions when oxidized. 
11.2.8 Geothermal Examples of Heat and Fluid Flow 
Many geothermal systems worldwide have been the subject of heat and fluid flow studies. Fluid 
flow in geothermal systems is controlled in part by thermal buoyancy effects, chemically 
controlled density contrasts, and channelized flow resulting from permeability barriers. Drilling 
of exploration and production wells in developed geothermal fields facilitates the collection of 
downhole temperature and pressure data. Production flow and tracer tests also permit the 
determination of formation permeability and fluid flow paths and rates. Reservoir simulation 
models have been widely used along with such data to predict future heat and fluid flow behavior 
in commercial geothermal reservoirs under production (e.g., Bodvarsson et al. 1993 [138618]; 
Steingrimsson et al. 2000 [156686]; also see Section 11.2.8.2). The ability of these models to 
accurately forecast changes in reservoir behavior provides confidence that similar models 
developed for Yucca Mountain will reasonably simulate future repository performance. Two 
aspects of heat and fluid flow in geothermal systems are discussed in detail below. The first 
topic is the role of faults and fractures in providing high-permeability pathways for fluid flow 
within the convecting geothermal reservoir. The second topic is the use of numerical models to 
create natural-state models and to simulate the effects of production and reinjection on 
geothermal reservoirs. 
11.2.8.1 Fracture-Dominated Fluid Flow 
Many geothermal systems have reservoir rocks with relatively low matrix permeabilities, but 
high overall formation permeability caused by the presence of a high-permeability fracture 
network (Bodvarsson and Witherspoon 1989 [156337], p. 3). For some systems, this network is 
dominated by a few large-scale faults that control both the location of surface thermal features as 
well as fluid flow in the subsurface. Several examples of these geothermal systems are described 
below. 
Dixie Valley, Nevada 
The Dixie Valley geothermal field is located along the active Stillwater normal fault, in an area 
of high regional heat flow in the Basin and Range province of Nevada. The production wells are 
targeted to intersect strands of this fault at depth. Interference and tracer tests conducted in this 
field demonstrate that the high-permeability wells are well connected by a high-permeability 
fracture network. In a tracer test at Dixie Valley, three tracer combinations were introduced into 
three wells (Adams et al. 1989 [156348], pp. 215217). Pre-test modeling based on the porous 
medium approximation identified seven well pairs that were expected to show tracer 
breakthrough. Only one well produced tracer, identifying a connected fracture network between 
the injection site and the producing well. The minimum velocity (based on a straight line 
between injection and the producing well) for the tracer front was 5 m/hr, and the minimum 
velocity for the tracer peak was 1.4 m/hr. As part of another investigation at Dixie Valley, a 
series of four tracer tests was performed (Rose et al. 1998 [156341]). Tracers were introduced in 
pulses in target injection wells located in the southern and central portions of the field. The 
tracers were detected only in a cluster of seven wells located between the injection wells. The 

amount of short-circuiting between the wells differed for each injection well, with one of the 
wells having a much shorter residence time than the others, indicating heterogeneity in the 
fracture network. Breakthrough curves presented by Rose et al. (1998 [156341], Figure 2) can 
be used to calculate tracer-front minimum velocities ranging from about 0.7 to 3 m/hr (average = 
1.6 m/hr) and peak minimum velocities ranging from about 0.4 to 0.8 m/hr (average = 0.6 m/hr). 
Silangkitang, Indonesia 
The Silangkitang geothermal field is one of several geothermal systems located along the Great 
Sumatran fault zone. The main thermal features are located along surface traces of this major 
strike-slip fault (Gunderson et al. 1995 [156361], p. 691). Exploration wells drilled directionally 
to penetrate the main trace of the fault encountered extremely high fluid flow rates within the 
fault zone (Gunderson et al. 2000 [156310], Figure 4, pp. 11841185). In contrast, nearby 
vertical wells that do not intersect the fault have very low formational permeabilities, thus 
underscoring the importance of the fault in providing high-permeability flow paths. Higher 
temperatures and increased alteration were encountered near the fault, which serves as an upflow 
zone for this geothermal system (Moore et al. 2001 [156320], pp. 11901191). 
Wairakei, New Zealand 
The Wairakei geothermal field is located in the Taupo Volcanic Zone, a tectonically active area 
that has been the site of voluminous Quaternary volcanism. Normal faults cutting the area appear 
to be the primary conduits for high-volume fluid flow. Grindley (1965 [154663]) identified three 
groups of wells based on their relative deliverabilities. Wells intersecting faults have very high 
permeabilities (>1 darcy) that cannot be precisely quantified because of a lack of pressure 
drawdown during production tests. Wells drawing on reservoir storage have pronounced 
drawdown, with calculated permeabilities ranging from 530 millidarcies. Nonproductive wells 
typically intersect hydrothermally cemented rocks with intrinsically low (<1 millidarcy) 
permeabilities. The intensely altered, impermable rocks serve to protect the producing reservoir 
from cold water encroachment. Tracer tests conducted at Wairakei (Jensen and Horne 1983 
[156643], Table 1) suggest minimum flow velocities along fractures that are as high as 38 m/hr. 
These flow velocities result from high-pressure gradients within the system; similar gradients are 
not expected for Yucca Mountain. 
Relevance to Yucca Mountain 
These geothermal examples show the importance of high-permeability fractures in the 
circulation of geothermal fluids. Numerous normal faults (i.e., Solitario Canyon, Bow Ridge, 
Dune Wash, Drill Hole Wash, Pagany Wash, Sever Wash, Sundance, Ghost Dance) have been 
identified at Yucca Mountain, but little is currently known about their permeability (BSC 2001 
[155950], Section 3.3.4.5.1). If these faults are permeable, then they could serve as fast fluid 
flow paths for infiltrating surface waters reaching the repository level, as well as pathways for 
dissolved radionuclide transport from the waste packages down to the water table. 
The presence of bomb-pulse tritium and 36Cl in water samples collected from core samples from 
the potential repository horizon within Yucca Mountain suggests that fault and fracture pathways 
have experienced relatively fast rates of fluid flow (Fabryka-Martin et al. 1997 [100145]). Based 

on these results, minimum fluid-flow velocities calculated using a distance of 300 m (distance 
from the surface to the sampled areas) and a maximum time of 50 years (first generation of 
bomb-pulse tritium and 36Cl) are on the order of 0.0007 m/hr; these rates are much slower than 
those observed in geothermal fields. Because the bomb-pulse tracer flow rate estimate is poorly 
constrained, a number of fluid flow experiments have been conducted along faults within the 
ESF at Yucca Mountain with the goal of obtaining better estimates of flow velocities. A series 
of in-situ flow tests was conducted in Alcove 4 between two boreholes 1.07 m apart that 
intersected a minor normal fault (Salve and Oldenburg 2001 [157316], Figure 8, p. 3049). 
Measured flow velocities along the fault ranged from 0.080.58 m/hr. In another test between 
Alcove 8 and Niche 3, the time (~840 hr) between water release and the onset of seepage along a 
fault that intersects both the main drift and cross-drift tunnels (Figure 11.2-4) and the distance 
between these two areas (~25 m) can be used to calculate a flow velocity of about 0.03 m/h 
(Salve et al. 2001 [156848]). The measured fluid velocities from these field experiments are 
significantly higher than those obtained from the bomb-pulse data and may reflect the need for 
surface infiltration rates to be high enough to initiate and sustain fracture flow (Flint et al. 2001 
[156351], pp. 1921, 24, 25). 
The percolation flux at Yucca Mountain is much lower than the fracture flow rates described 
above. The percolation flux depends on the magnitude and spatial distribution of surface 
infiltration rates, as well as other factors, such as the presence of fast flow paths and lateral 
diversion within low-permeability intervals. Present-day infiltration rates are estimated to vary 
from 080 mm/yr, with an average value of about 510 mm/yr, for the potential Yucca Mountain 
repository block area (Flint et al. 2001 [156351], pp. 2223). Thus, it is critical to understand the 
role of faults and fractures at Yucca Mountain and how these features could serve to accelerate 
and/or focus fluid flow within the potential repository. 
11.2.8.2 Heat and Fluid Flow Simulations for Geothermal Systems 
Numerical simulation of geothermal fields has been performed successfully for more than three 
decades. The Code Comparison Study (Molloy 1981 [156407]) evaluated several geothermal 
simulators with six test problems. The codes tested all performed reasonably well, indicating 
that the physics of the test problems were correctly represented. Numerical simulation of 
geothermal fields has proved to be of great economic importance in aiding geothermal 
companies to understand where to drill and to predict production capacity (Simmons and 
Bodvarsson 1997 [126511]). In a recent examination of geothermal simulations, more than 100 
field simulations have been carried out worldwide since 1990 using a variety of simulators 
(OSullivan et al. 2001 [156353]). 
Over the decades of geothermal reservoir simulation, a robust modeling process has been 
developed. The process includes data collection and evaluation, conceptual model development, 
numerical model design, natural-state modeling, history matching, prediction, and post-auditing. 
Each step is dependent on the preceding steps, and thus changes in any preceding step require 
modifications in all subsequent steps. 
In the first step, all available data are evaluated. The data may be from several sources, 
including flow tests, well logs (temperature, lithology, electrical resistivity), fluid chemistry, 
self-potential surveys, measurements on core samples, topography, location and flow rates from 

hot springs and fumaroles, seismic data, precision gravity surveys, and other techniques. The 
data evaluation may be performed by individuals from many disciplines, yielding a conceptual 
model that is typically distilled into a few plan- and cross-sectional schematics providing an 
understanding of how the reservoir works. 
The numerical model is constructed to resemble the conceptual model. Region size, gridblock 
sizes, boundary conditions, fluid chemistry, and equations of state are selected and parameters 
are assigned for each gridblock. The first step in model calibration is natural-state modeling. In 
natural-state modeling, the numerical model is tested by placing a heat source into the system at 
some time in the past (usually thousands to millions of years ago) and running the model forward 
to obtain a match with current measurements. If an adequate match is not obtained, parameters 
are altered within reason and the process is repeated. Many iterations are often required, and this 
procedure may be partially automated (White et al. 1997 [156340]; Bullivant and OSullivan 
1998 [144410]; Finsterle 1999 [104367]). The importance of field features may be identified in 
this step, often leading to inferences of fluid inflows and faults. 
The second step in model calibration is history matching, which can be performed when fluids 
have been produced from the geothermal system. In history matching, the field perturbation 
(caused by fluid extraction) is modeled, with the results compared to field measurements 
(temperature, pressure, enthalpy, brine composition). Again, parameters are adjusted until a 
reasonable match is obtained. Since natural-state modeling is performed for long time frames 
and history matching over significantly shorter time frames (years to decades), different types of 
parameters can be inferred. In natural-state modeling, parameters such as permeability are 
inferred. In history matching, storage-type parameters like porosity are inferred. Changes in 
parameters at any stage require verification in earlier stages. Calibration of a model using both 
natural-state modeling and history matching is a significant milestone in the creation of a viable 
reservoir model and becomes increasingly difficult as the amount of data increases. 
Upon completion of successful natural-state modeling and history matching, the model is used 
for predictive purposes. Geothermal fields are modeled for a variety of reasons, but generally to 
devise a strategy for energy extraction. These models are generally evaluated and updated when 
development is planned. Few post-audits of geothermal field models have been published (post 
audits of two fields were found in the literature), although model performance is often monitored 
and demonstrated. The post-audit of Olkaria East Geothermal Field, Kenya (Bodvarsson et al. 
1990 [136384], pp. 399407) showed that the field-wide decline in steam rate agreed very well 
with predictions. A well-by-well comparison identified adequate predictions for 75% of the 
wells. Many of the wells for which prediction was inadequate had limited production when the 
initial model was constructed, and thus there was insufficient history on which to base the 
predictions for these wells. In a post-audit of the Nesjavellir Field, Iceland, Bodvarsson et al. 
(1993 [138618]) evaluated predictions made with a 1986 model for pressure decline and 
enthalpy changes. Acceptable agreement was reported between modeled and measured data 
(Figure 11.2-5), particularly considering that the prediction time (6 years) was longer that the 1 
3 yr calibration period. A second audit was performed of the Nesjavellir geothermal system 
(Steingrimsson et al. 2000 [156686]) because the model underestimated enthalpy decline in some 
wells. Recalibration led to slight changes in the conceptual model within the producing region of 
the reservoir. The new model matched well data better, but the larger-scale reservoir 
performance predictions remained unchanged. 

The geothermal industry relies heavily on the use of models, and at many fields several 
generations of models have been used. Beginning in the early 1980s, UNOCAL developed and 
maintained 3-D models of U.S., Philippine, and Indonesian geothermal fields (e.g., Williamson 
1992 [156613]; Strobel 1993 [156614]; Murray et al. 1995 [156612]). The Wairakei geothermal 
field (New Zealand) has been modeled since the late 1960s, including many types of models and 
levels of complexity (O'Sullivan et al. 1998 [154567]). The Kawerau geothermal field (New 
Zealand) has also been extensively modeled for more than a decade (White et al. 1997 
[156340]). These models have been upgraded over time as new information, codes, and 
techniques became available. The accumulated longevity of the models at a particular field 
indicates a significant degree of confidence in geothermal reservoir modeling. 
Application to Yucca Mountain 
There are a number of similarities and differences between modeling geothermal reservoirs and 
modeling the potential high-level nuclear waste repository at Yucca Mountain. The volume and 
number of dimensions modeled at Yucca Mountain are similar to those employed for geothermal 
reservoir modeling. The number of gridblocks in Yucca Mountain models ranges from hundreds 
to millions. The time scale for Yucca Mountain THC coupled process models is similar to the 
time scales of natural-state geothermal modeling, but significantly exceeds the time scale of 
history-matching reservoir models used to predict future reservoir behavior. The temperature 
and pressure conditions expected at Yucca Mountain are well within the range observed and 
modeled for geothermal reservoirs. 
The aims of modeling geothermal fields and modeling Yucca Mountain are different. 
Geothermal reservoirs are generally modeled to optimize energy extraction for economic gain. 
To that end, fluid extraction and injection rates, enthalpy, and the number and location of 
replacement wells are needed. Modeling for the potential Yucca Mountain repository is 
performed to describe the environment within the repository drifts and to assess the potential for 
release of the emplaced radionuclides and their fate. Data collection at Yucca Mountain to 
constrain these models has been extensive; however, much of it is related to small-scale 
measurement and requires scaling to be adequately represented in the numerical models. 
Repository performance depends on: (1) the amount of water that may seep into the repository, 
(2) the temperature and humidity near the waste packages, and (3) the ability of the natural 
system to sorb and retain radionuclides possibly escaping the repository (Bodvarsson et al. 1999 
[120055], pp. 3, 5). As understanding geothermal systems requires modeling at various scales 
(i.e., well scale, zone scale, and field scale), so modeling for Yucca Mountain requires modeling 
at multiple scales (drift scale, mountain scale), but in addition requires an understanding at 
smaller scales, because flow on smaller scales may impact repository performance. 
Prediction time frames for geothermal fields range from 1050 years. It is generally accepted in 
the geothermal-modeling community that predictions for a well-studied geothermal field are 
valid only for a time scale on the order of magnitude of the history-matching data (Bodvarsson et 
al. 1993 [138618]), because of uncertainties in assigning parameters to the model. It is not 
realistic to collect history-matching data for a 10,000-year period of model confidence for the 
thermal system at Yucca Mountain. Tests applying thermal perturbations to Yucca Mountain are 
planned for as long as eight years. Because of this, the modeling efforts for the repository have 
investigated potential behavior for a large range of possible conditions, including higher and 

lower percolation fluxes resulting from climate changes, different heat loads, and different waste 
package arrangements. Sensitivity analyses have been performed for a variety of model 
parameters (Bandurraga and Bodvarsson 1999 [103949]). 
Modeling for the Yucca Mountain repository has benefited greatly from the foundation produced 
from the robust modeling techniques developed in geothermal modeling. Wu et al. (1999 
([117161], pp. 186188) reviewed many of the earlier thermal-hydrologic (TH) modeling efforts. 
These coupled, multiphase, multicomponent models simulate the flow and distribution of 
moisture, gas and heat at Yucca Mountain for use in predicting current and future conditions in 
the UZ. For example, Tsang and Birkholzer (1999 [137577]) used a 3-D coupled TH numerical 
model to predict the results of the Single Heater Test at Yucca Mountain. They obtained good 
agreement between measured temperatures and model results, and the simulated dryout and 
condensation zones were consistent with radar tomography and air-permeability data. 
More recent Yucca Mountain modeling efforts (e.g., BSC 2004 [167974]) have used the 
TOUGHREACT code (Xu and Pruess 2001 [156280]), which couples reactive chemistry and 
transport to the TOUGH2 code used to create many of the TH models. The coupled THC 
models incorporate heat and fluid flow, chemical transport, kinetic and equilibrium mineralwater 
reactions, and coupling between mineral dissolution and precipitation, porosity, and 
permeability for a fracture-matrix system. Three heater tests have been performed (the Large 
Block Test, the Single Heater Test, and the still-cooling Drift-Scale Test [DST]) to allow 
assessment of the numerical models. These tests provide data (for validation of Yucca Mountain 
numerical models) that are analogous to production data used for history-matching exercises 
performed on geothermal reservoir models. The duration of these thermal-perturbation tests is 
short relative to the time scale of the repository, with the DST having a four-year heating phase 
followed by a four-year cooling phase. These thermal tests have been used to validate the THC 
model by comparing measured gas and water chemistry from the DST to the results of 
simulations obtained using the DST THC model (BSC 2004 [167974]). The THC model 
captures the observed changes in pH and the concentrations of dissolved aqueous and gas species 
such as Na, K, Ca, Cl, HCO3, SiO2, and CO2 over time for areas that have different thermal 
histories, and is consistent with the results of TH modeling (BSC 2004 [167974], Sections 7.1.8 
7.1.11). 
Simulations of the anticipated system at Yucca Mountain have been performed using coupledprocess 
modeling to assess THC effects on seepage and fluid flow within the near-field 
environment (BSC 2004 [167974]). Fracture porosity reductions in the near-field environment 
resulting from the precipitation of calcite and amorphous silica are predicted to be approximately 
47%, resulting in predicted localized reductions in permeability and fluid flow caused by THC 
processes (BSC 2004 [167974], Section 6.8.5.4, Figures 6.8.406.8.42). Similar to post-audit 
reviews of geothermal reservoir models, Yucca Mountain models should be regularly updated, as 
new data become available, to maximize their effectiveness as a repository management tool. 
11.2.9 Chemical Transport in Geothermal Systems 
The transport of chemical species in geothermal systems is intimately linked to advective fluid 
flow. Chemical constituents of geothermal fluids are commonly used to infer deep reservoir 
temperatures, identify sources of fluids (such as magmatic, meteoric, connate, and condensate 

waters), and monitor important processes such as injectate breakthrough and influx of ground 
waters into producing portions of geothermal reservoirs. Because fluid velocities are rapid (and 
often faster than chemical reequilibration rates) within most geothermal systems, the chemistry 
of reservoir fluids sampled at surface thermal features can be used to estimate reservoir 
conditions. For example, chloride springs found at many geothermal systems are typically 
derived in large part from deep reservoir fluids. The chemical compositions of geothermal 
waters are commonly used to determine reservoir temperatures using a variety of silica and alkali 
geothermometers (Fournier 1992 [105419]). Natural and introduced chemical tracers are used to 
monitor fluid velocities, estimate flow paths, examine fracture-matrix interaction, and identify 
the sources of fluids within geothermal systems. The presence of hydrothermal minerals along 
veins and fractures in fossil geothermal systems is evidence for chemical transport (and 
subsequent mineralization) in these systems. 
11.2.9.1 Geothermal Tracer Tests 
For conservative tracers (such as iodine and chloride), tracer travel time represents the flow rate 
of advecting fluid within the geothermal reservoir. Tracer tests at Dixie Valley and Wairakei 
(previously summarized in Section 11.2.8.1) indicate minimum tracer velocities ranging from 0.7 
to 38 m/hr. In some Japanese fields, tracer returns have been observed at rates of up to 100 m/hr, 
indicating high-conductivity fractures. Observed tracer speeds in the Hatchobaru field are as 
high as 80 m/hr (Horne 1982 [156362], p. 501). 
Naturally occurring tracers are commonly used in geothermal fields to evaluate important 
processes such as heat flow, groundwater influx, and reinjectate breakthrough. Measurements of 
the total amounts of chloride and boron (nonreactive components that are often magmatic in 
origin) associated with surface feature discharges have been used to estimate heat flow values of 
geothermal systems (e.g., Fournier et al. 1976 [156817]; Sorey and Lewis 1976 [156809]). 
Because reinjected fluids have higher chloride contents than produced fluids (due to the 
concentration of chloride in the liquid phase resulting from the removal of steam), the arrival of 
reinjected waters in production zones can be detected and monitored by tracking chloride 
contents of production well brines. Chloride generally behaves in a conservative fashion (it is 
nonsorbing and is not involved in mineral precipitation, except in very saline water), and thus 
generally reflects the effects of mixing and boiling only. 
Bulalo, The Philippines 
Tracer tests conducted at the Bulalo geothermal field have been used to monitor the dispersal of 
injected fluids within the reservoir, track the influx of groundwater influx, and identify highpermeability 
flow paths (Villadolid 1991 [156656]). Changes in chloride contents and fluid 
enthalpies were used in production wells to identify the contribution of reinjected fluids in 
production wells. Elevated concentrations of tritium were interpreted to indicate zones where 
downflux of groundwater along permeable flow paths occurred. Rapid increases in magnesium 
concentrations following acid stimulation in neighboring wells were used to identify fast flow 
paths between wells. 

11.2.9.2 Application to Yucca Mountain 
Gravity-driven fracture flow is predominant through the fractured units with low matrix 
permeability at Yucca Mountain. Chemical transport accompanying percolation flux and 
associated seepage into cavities over time is evidenced by the precipitation of calcite and opal 
along fracture and cavity surfaces. Textural observations and fluid inclusion, isotopic, and 
geochronologic data on the coatings suggest that these secondary minerals were deposited from 
infiltrating meteoric water under unsaturated conditions (Whelan et al. 2001 [154773], p. 6). 
Using an equilibrium evaporation model to predict calcite and opal precipitation associated with 
seepage into lithophysal cavities, Marshall et al. (2000 [151018], p. 4) calculated that the total 
seepage volume over the past 10 million years (m.y.) is approximately 5  104 times greater than 
the volume of secondary calcite precipitated over the same time period at Yucca Mountain. This 
model assumes that all water is calcite-saturated, and no significant dissolution of calcite has 
occurred. The seepage flux estimated from this model (4  10-6 mm/yr (Marshall et al. 2000 
[151018], p. 5)) may be used to calibrate predicted rates of seepage into drifts for numerical 
models (e.g., Birkholzer et al. 1999 [105170]) as well as provide insights relating to chemical 
transport rates and mechanisms at Yucca Mountain. 
A key factor affecting chemical transport at Yucca Mountain involves possible interaction 
between minerals and dissolved constituents. The effects of ion exchange are demonstrated by 
the marked difference in strontium concentrations of perched waters in the Topopah Spring and 
Calico Hills tuffs. The strontium contents of perched waters in the UZ-14 and WT-24 boreholes 
(that sample the stratigraphically higher Topopah Spring tuff) range from 169240 ppm 
(Sonnenthal and Bodvarsson 1999 [117127], Table 3). Much lower strontium concentrations (3 
11 ppm) were measured for perched waters from the SD-7, SD-9, and NRG-7A boreholes in the 
Calico Hills tuff. The lower strontium values from these samples were interpreted by Sonnenthal 
and Bodvarsson (1999 [117127], pp. 119120) to result from ion exchange between the perched 
waters and Ca-rich zeolites, which are abundant in the Calico Hills tuff (see Figure 7-2). These 
zeolite-rich tuffs form an important part of the geologic barrier inhibiting radionuclide transport 
from the repository down to the water table at Yucca Mountain. 
11.2.10 Geothermal Examples of Boiling and Dryout 
Many geothermal systems have localized boiling zones resulting from upward flow of highenthalpy 
fluids, or from depressurization induced by geothermal production. Dryout zones 
(areas where fluids have boiled to dryness) are much less common, and typically are associated 
with the transition between liquid-dominated to steam-dominated geothermal systems. The 
effects of boiling on fluid chemistry, mineral precipitation, and reservoir permeability have been 
documented for a number of natural-state and producing geothermal systems. Dryout zones are 
more transient features, and thus are more difficult to characterize. However, as discussed in 
Section 11.2.10.2, detailed study of cores from the Karaha-Telaga Bodas geothermal field 
provides some insights as to how these zones develop and their significance. Summaries of 
some relevant geothermal examples of boiling and dryout are presented below. 

11.2.10.1 Boiling in Geothermal Systems 
Boiling is a common phenomenon in high-enthalpy geothermal systems. Many of these systems 
have high-temperature (=100C) thermal features (boiling hotsprings and superheated fumaroles) 
resulting from the depressurization of high-enthalpy fluids ascending to the surface. Localized 
boiling within the reservoir can also occur as a result of production of geothermal fluids, which 
decreases reservoir pressure. The process of boiling results in increased concentrations of 
dissolved constituents in the residual liquid phase, as well as the partitioning of volatile species 
(such as CO2) into the gas phase. These changes often lead to the precipitation of phases such as 
amorphous silica and calcite. Several examples of the observed effects of boiling in geothermal 
systems are given below. 
Waiotapu, New Zealand 
The Waiotapu geothermal system is the largest of the 20 major geothermal systems located in the 
Taupo Volcanic Zone on the North Island of New Zealand (Hedenquist 1991 [156315]). Surface 
thermal features include fumaroles and associated acid sulfate springs along the flanks of dacite 
cones, and numerous chloride, acid-sulfate and mixed composition hot springs located in 
Waiotapu Valley. The chloride springs represent the liquid component of the hot (=230C) 
reservoir fluid that feeds these surface features. 
Champagne Pool, one of the largest of the chloride springs at Waiotapu, has a surface 
temperature of 75C (Hedenquist 1991 [156315], Table 1, pp. 2756, 27582764). It derives its 
name from the outgassing of CO2 near the surface, thus giving it the appearance of champagne. 
The elevated chloride contents of this feature (1,898 ppm) suggest that it has experienced 
minimal dilution from meteoric fluids. The effects of boiling and evaporation on the waters from 
this feature can be seen by the isotopic enrichment in deuterium and 18O resulting from the loss 
of vapor. The dissolved silica concentration of 445 ppm is much higher than the equilibrium 
solubility concentrations of both quartz and amorphous silica at the pool temperature, and results 
from the processes of boiling and cooling of a hot (=230C) reservoir fluid as it ascends to the 
surface. An extensive silica sinter deposit surrounds this thermal feature, and similar deposits 
are common for many of the other chloride springs at Waiotapu. 
Cerro Prieto, Mexico 
Localized aquifer boiling occurs in the shallow two-phase reservoir at Cerro Prieto (Truesdell et 
al. 1984 [156350]). Boiling increases the total dissolved solids (TDS) concentrations in the 
residual liquid through steam production, but also causes a decrease in fluid temperatures, thus 
reducing the solubility of most mineral phases. The increase in dissolved silica concentrations 
and decrease in silica solubility often results in the precipitation of silica polymorphs. Boiling 
also results in the partitioning of CO2 into the gas phase, thus causing pH to increase and calcite 
to precipitate. 
Large decreases (up to 70%) in discharge rates from wells located in the boiling zone at Cerro 
Prieto (Figure 11.2-6) have been interpreted to result from the precipitation of quartz and calcite, 
which decreased permeability for these zones (Truesdell et al. 1984 [156350], Table 2, p. 226). 

This interpretation is supported by the observed decrease in silica and bicarbonate contents of the 
produced fluids of these wells with time. 
Relevance to Yucca Mountain 
For the higher-temperature operating mode at Yucca Mountain, a heat pipe may form above the 
repository when temperatures reach boiling. Water originally stored in the rock matrix, 
combined with water infiltrating from the surface, would boil near the margins of the heated 
drifts and migrate (as vapor) to cooler surrounding areas, where condensation would occur. 
Similar to the cases mentioned above, boiling will lead to increases in the concentration of 
dissolved species in the residual liquid phase, resulting in supersaturation and subsequent 
precipitation of phases such as amorphous silica. 
The impact of boiling on mineral precipitation at Yucca Mountain should be significantly less 
than that observed in most geothermal systems because of the restricted area where boiling 
would occur, the much smaller quantities of fluid involved, and the lower initial concentrations 
of dissolved silica. A simple calculation using the matrix porosity, saturation, and pore-water 
silica concentrations and fracture volume can be made to estimate the maximum amount of silica 
that could potentially precipitate in adjoining fractures (Simmons 2002 [157578], SN-LBNLSCI-
190-V2, p. 79). Assumptions for this model include a matrix porosity of 10%, a matrix fluid 
saturation of 90%, a silica pore-water concentration of 70 mg/L, and a fracture volume of the 
rock of 0.5%. Also assumed is that with boiling, the water and associated dissolved silica are 
completely transferred from the matrix pore space into the fractures, where the water is 
subsequently boiled to dryness so that all of the dissolved silica precipitates as amorphous silica. 
For a 1 m3 block of rock undergoing this process, that would correspond to a matrix water 
volume of 90 L and a dissolved silica amount of 6.3 g. The fracture volume for this block would 
be 5 L, and using a density of 2100 g/L for amorphous silica, the volume of amorphous silica 
available for precipitation is thus equivalent to 0.003 L. This corresponds to 0.06% of the 
available fracture volume. This very minor reduction in fracture porosity would result in a 
negligible reduction in fracture permeability. 
Another bounding calculation can be made by estimating the amount of silica precipitation 
resulting from transport of additional dissolved silica to the boiling zone resulting from 
continued influx of infiltrating water from the surface (Simmons 2002 [157578], SN-LBNL-SCI- 
190-V2, p. 80). This calculation uses the same 1 m3 block as a starting point, with a fracture 
volume of 0.5%, a fluid infiltration rate of 5 mm/yr, a fluid composition of 70 mg SiO2/L, and 
assumes that: (1) all infiltrating water is focused into the fractures and (2) all of the water 
entering this zone from above undergoes complete boiling, resulting in the precipitation of 
dissolved silica as amorphous silica. For a boiling zone duration of 1,200 years, this translates 
into an infiltration fluid volume of 6000 L with a corresponding silica amount of 420 g. Using 
the density and fracture volumes given above, this corresponds to 4% of the available fracture 
volume. This simplistic bounding calculation is meant to illustrate the potential for fracture 
sealing at Yucca Mountain. Migration of the boiling front with time at Yucca Mountain would 
result in a larger area with reduced porosity and permeability, but with smaller average 
reductions. Variability in fracture apertures could lead to sealing of small aperture fractures and 
focussing of flow into larger aperture fractures. A fracture sealing experiment conducted in a 
block of ash flow tuff and accompanying numerical simulations demonstrate that similar 

amounts of total fracture sealing could result in large (up to two orders of magnitude) reductions 
in permeability in the case where mineralization is highly focused (Dobson et al. 2003 [165949]). 
One factor that could significantly increase the amount of silica precipitation in the fracture zone 
is the transport of additional dissolved silica to the boiling zone through reflux of fluids 
associated with a heat pipe. The return of condensed vapor that has dissolved silicate minerals 
back into the boiling zone could effectively transport significant amounts of silica into the 
fractures of the boiling zone. However, it is difficult to quantify the impact of this process. THC 
coupled-process modeling of the near-field environment, using a homogeneous fracturepermeability 
model, predicts that porosity reduction caused by precipitation of silica and calcite 
will be approximately 47% over the initial 2,400 years of the simulation (BSC 2004 [167974], 
Section 6.8.5.4). This fairly small change relative to geothermal systems is in part due to the 
much lower fluid fluxes and lower temperatures expected at Yucca Mountain. 
Boiling would not occur for the lower-temperature operating mode at Yucca Mountain. 
Moderately elevated temperatures (~80C) around the drift area for this case would lead to 
higher amounts of evaporation, and thus result in higher concentrations of dissolved constituents 
in the remaining fluids in the area around the heated drifts. However, the amount of silica 
precipitation calculated above for the higher-temperature operating mode would be much 
reduced for the lower-temperature operating mode. THC simulations performed for the nearfield 
environment for the lower-temperature operating mode predict that less than 1% porosity 
reduction will occur, because amorphous silica will remain undersaturated except in areas 
adjacent to the drift wall, where substantial evaporation will take place (BSC 2001 [155950], 
Section 4.3.6.5). 
11.2.10.2 Dryout Zones in Geothermal Systems 
Dryout is less common than boiling in geothermal systems because most systems are liquidsaturated 
and, thus, always contain some water. However, dryout zones do occur in steamdominated 
geothermal systems, and evidence of these zones in such a system is presented in the 
summary below. 
Karaha-Telaga Bodas, Indonesia 
The Karaha-Telaga Bodas geothermal system, located on the island of Java in Indonesia, consists 
of a horizontally zoned reservoir with an upper condensate layer, an intermediate vapordominated 
zone, and an underlying deep liquid-dominated zone (Allis et al. 2000 [156317], 
Figures 4 and 5, pp. 220221). Mineralogic and fluid inclusion studies of core samples from the 
T-8 corehole reveal a complex history, with calcite and quartz (after chalcedony) veins present at 
shallower depths, and veins containing epidote, actinolite, albite and quartz (after chalcedony) 
present in deeper samples (Moore et al. 2000 [156319], pp. 260262). The precipitation of 
chalcedony (revealed by botryoidal textures) at elevated temperatures is unusual (Figure 11.2-7) 
and is interpreted to result from extreme silica supersaturation resulting from decompressional 
boiling (Moore et al. 2000 [156319]). The abundance of vapor-rich inclusions in the vein 
minerals is consistent with this model. Many of the hydrothermal minerals are coated with scale 
(consisting of Ti- and K-bearing phases along with iron chloride, and halite) with desiccation 
cracks (Figure 11.2-8). These minerals are thought to have formed as a result of dryout (Moore 

et al. 2000 [156319], pp. 260-261). The youngest fluid inclusions, associated with scale-coated 
anhydrite, have extremely high salinities (31% NaCl equivalent), and Moore et al. (2000 
[156319], pp. 262263) interpreted that the inclusions and scale formed as a result of condensate 
boiling to dryness. The high solubility of the chloride minerals suggests that the rocks 
containing the scale have not been subjected to rewetting after they were formed. 
Relevance to Yucca Mountain 
Dryout is predicted to occur in the rock mass around the repository drifts at Yucca Mountain (for 
the higher-temperature operating mode) as the waste packages transfer their heat to the 
surrounding environment. The size of the dryout zone will vary with time and may extend up to 
13 m away from the drift walls (as previously mentioned in Section 11.2.5) (BSC 2004 [167974], 
Sections 6.5.5.1 and 6.8.5.2). During the dryout phase, liquid water will be converted to water 
vapor, which will effectively displace air from this zone. This is important because the oxygen 
necessary for many corrosion reactions will only be present in low concentrations. As the heat 
output from the waste package diminishes with time, dryout zones will gradually undergo 
rewetting from influx of condensate and precipitation infiltration as temperatures drop below the 
local boiling point. The rewetting process will be accompanied by an influx of air (BSC 2004 
[167974], Section 6.8.5). 
In the dryout zone near repository drifts, water will be driven from the pore space in the rocks. 
The rock has a matrix porosity of about 1015% (BSC 2004 [167974], Table 6.4-1), which is 
about 90% filled with water in the natural condition (90% water saturation). This water is 
expected to be an important source of circulating water near the repository. Heating of the 
matrix rock, even to temperatures below boiling, may cause dryout in fractures. As the rock 
mass heats following waste emplacement, the volume of the dryout zone may increase to include 
regions formerly altered in the heat pipe. Mineralogic changes expected in this region will 
include precipitation of minerals in fractures (see discussion above), dehydration of naturally 
present sorbing clay minerals, carbonate mineral decomposition, and deposition of minerals on 
fracture faces from liquid driven from the rock. 
With rewetting of the dryout zone, some of the more soluble mineral salts are likely to be 
redissolved. This could initially result in the formation of fairly saline fluids that could cause 
corrosion problems with the waste package in the drift. However, with continued seepage into 
the former dryout area, the resulting fluids will become increasingly more dilute. Dryout will be 
much less pronounced for the lower-temperature (sub-boiling) operating mode. 
11.2.11 Geothermal Examples of Condensation and Mineral Dissolution 
The processes of condensation and mineral dissolution and their effects can also be detected in 
many geothermal systems. Condensation of upflowing steam, when it comes into contact with 
cooler meteoric waters in the shallow portions of geothermal systems, results in the production 
of steam-heated waters (e.g., Hedenquist 1991 [156315], pp. 27562757). These dilute fluids 
often have fairly distinct chemical compositions and often reflect the effects of the gas phase 
accompanying the steam. Waters that receive an influx of CO2 are typically bicarbonate fluids, 
whereas those interacting with H2S become acid-sulfate waters. The acid-sulfate waters are 
often associated with acid-sulfate alteration, where feldspars readily alter to kaolinite. 

Mineral dissolution is not as readily evident in geothermal systems, but can be detected in core 
samples. At The Geysers geothermal field, corroded faces of quartz crystals found in 
hydrothermal veins indicate that these crystals underwent partial dissolution prior to being coated 
in later chalcedony (Moore et al. 2000 [156318], Figure 9, pp. 17221723). Similar dissolution 
features are also observed for calcite. These textural features (Figure 11.2-9) are interpreted to 
represent dissolution resulting from the downward percolation of condensate near the site of 
condensation in the upper portion of a vapor-dominated heat pipe (Moore et al. 2000 [156318], 
Figure 11, pp. 17311732). 
11.2.11.1 Relevance to Yucca Mountain 
Condensation and dissolution are processes that are likely to occur at Yucca Mountain. A tuff 
dissolution experiment was conducted to simulate mineral dissolution by condensate water in 
fractured tuff (Kneafsey et al. 2001 [154460]; Dobson et al. 2003 [165949]). Deionized water 
containing dissolved CO2 was flowed through a column containing crushed Topopah Spring tuff 
at a temperature of 94C. The reacted water exiting the column was regularly collected and 
analyzed. The experiment achieved a pseudo-steady-state flow composition after 11 days. Silica 
(92 ppm) was the dominant dissolved consituent. A similar plug-flow reactor experiment (using 
higher temperature conditions) was conducted by Johnson et al. (1998 [101630]), and a series of 
unsaturated nonisothermal vertical column tests were conducted by Lowry (2001 [157900]). 
These experiments demonstrate the ability of condensate waters to dissolve (and subsequently 
transport) significant quantities of dissolved constituents. As mentioned in the discussion on 
boiling, reflux of condensate fluids containing dissolved silica could serve as an important source 
for the generation of fracture-plugging minerals precipitated at the boiling front. 
11.2.12 Geothermal Examples of Mineral Alteration and Precipitation 
Mineral alteration and precipitation are ubiquitous in geothermal fields. The nature and extent of 
alteration depends on a variety of factors, including temperature, initial rock mineralogy, initial 
water and gas chemistry, fluid/rock ratios, and the rock surface area exposed to fluids. Many 
geothermal systems show a series of mineral assemblages that corresponds to different 
temperature and fluid chemistry regimes (e.g., Muffler and White 1969 [156650]; Arnrsson 
1995 [156321]). Mineral alteration and precipitation can significantly affect porosity, 
permeability and sorptive properties (at least locally) of both matrix and fractures, resulting in 
the sealing of former fluid flow pathways. 
Precipitation of new minerals in vugs, pore spaces, and fractures can occur when fluids reach 
supersaturation with respect to dissolved constituents. The rate of precipitation is often 
controlled by kinetic processes and, thus, is highly dependent on factors such as nucleation sites 
and temperature. Supersaturation can be caused by processes such as boiling, cooling, heating 
(in the case of minerals with retrograde solubility, such as anhydrite and calcite), degassing, and 
mixing of two distinct fluids. The effects of boiling have previously been discussed, so this 
section will focus on the other processes mentioned. 

11.2.12.1 Hydrothermal Alteration and Seal Formation in Geothermal Systems 
Imperial Valley 
The effects of water-rock interaction have been studied at a number of geothermal fields (Salton 
Sea, East Mesa, Heber, Brawley, Cerro Prieto, and the Dunes) within the Imperial Valley (e.g., 
Muffler and White 1969 [156650]; Schiffman et al. 1985 [154644]; Cho et al. 1988 [154599]). 
Elders (1987 [154632]) examined the Salton Sea geothermal field as a potential natural analogue 
for evaluating processes related to radioactive waste storage. One of the features examined was 
the impact of water-rock interaction and mineralization on fluid flow and solute transport. While 
primary lithology plays a major role in the distribution of permeability and porosity within the 
field, processes such as compaction and hydrothermal alteration have significantly modified 
these rock properties. Carbonate-cemented sandstones form the primary caprock for the Salton 
Sea geothermal system, and represent the first of four distinct mineralogic zones related to 
hydrothermal alteration. Within this sealed zone, calcite cement fills up to 50% of the pore 
space, resulting in very low matrix permeabilities for this interval (Elders and Cohen 1983 
[157502], p. 100). Matrix permeability appears to favor horizontal fluid flow, as low 
permeability shale interbeds serve as barriers to vertical fluid flow. Fractures provide fluid flow 
pathways that can cut across these lithologic barriers. Complex sequences of fracture 
mineralization observed at the Salton Sea indicate that fractures have been episodically opened 
and sealed throughout the life of the geothermal system (Elders 1982 [154602] pp. 6364). 
Silica sealing has been documented at the Dunes geothermal system (Bird and Elders 1976 
[154601], Figure 3, p. 289). An exploration well drilled at this prospect (DWR No. 1) has a 
depth of 612 m, with a maximum temperature of 104C. Fluids sampled from this well are NaCl 
brines with up to 4,000 ppm TDS. Seven distinct zones of sandstones and conglomerates have 
undergone intensive silicification, which significantly reduced porosity and permeability. These 
silicified zones (Figure 11.2-10) are located in what originally were the most permeable strata 
within the sedimentary section. Silicification appears to be most intense near the upper portions 
of these units, immediately below low-permeability shale interbeds. The silicified zones have 
mineral assemblages of quartz + adularia + hematite and quartz + adularia + pyrite, reflecting 
enrichments of silica and potassium to these zones caused by mass transfer accompanying 
hydrothermal alteration. Brittle fractures developed in the silicified zones. The precipitation of 
silica is thought to be caused by the lateral migration of hot brine to a cooler environment. 
Smectite and kaolinite have reacted with potassium-rich brines to form adularia. 
Wairakei Geothermal Field, New Zealand 
Fluid chemistry and mineralogy data from the Wairakei field were used to test the EQ3/6 
geochemical modeling codes and the GEMBOCHS thermodynamic databases (Bruton 1995 
[100105]). Water and gas compositions obtained from well samples were used to reconstruct 
reservoir fluid compositions, and these fluid compositions were used as input for the EQ3/6 code 
to calculate equilibrium mineral assemblages. These calculated assemblages were then 
compared to the observed downhole mineralogy for these wells to help identify which 
thermodynamic datasets produced the best match between the observed and calculated 
mineralogy. Lower temperature portions of the reservoir exhibit similar mineralogy (including 
zeolites such as mordenite, clinoptilolite, stilbite, and dachiardite) to that observed in the Yucca 

Mountain tuffs. Vein mineral assemblages contain fewer phases than those found associated 
with the matrix. Bruton (1995 [100105], p. 18) inferred that the fracture, vein, and vug minerals 
are the product of a fluid-dominated system, whereas the more complex matrix alteration 
mineralogy results from high rock-water ratios. A discussion of these and other studies 
involving mineral equilibria and fluid chemistry at the Wairakei geothermal system is presented 
in BSC (2004 [168845], Section 5.4.4.4.3). 
Medicine Lake Geothermal Field, California 
The Quaternary Medicine Lake volcano in northern California is host to a high-temperature 
geothermal system. Exploratory drilling has revealed that the geothermal reservoir is capped by 
hydrothermally altered rock rich in smectite-group swelling clays that form a barrier to fluid flow 
(Hulen and Lutz 1999 [154600], pp. 217, 219). Glassy dacitic to rhyolitic tuffs and pumiceous 
lavas have been strongly altered to smectites, calcite, zeolites, quartz, potassium feldspar, 
hematite, and pyrite. This argillic alteration mineral assemblage also fills fractures and vugs, and 
forms a hydrologic barrier between a shallow, cool groundwater zone and a deeper, hot 
geothermal reservoir. 
Fossil Systems 
Fossil hydrothermal systems also demonstrate the impact that water-rock interaction has on 
permeability. Figures 11.2-11 and 11.2-12 illustrate variations in permeability for interbedded 
siliceous diatomite and pumiceous tuff from northern Japan (Chigira and Nakata 1996 [156349], 
Figure 2, Table 1; Chigira et al. 1995 [156364], pp. 7576). An andesite dike intruded these 
bedded rocks, inducing a hydrothermal system that resulted in the alteration of the tuffs and 
diatomite, thereby reducing permeability up to four orders of magnitude. While the initial 
temperatures immediately adjacent to the dike probably approached those of the andesite magma 
(~1000C), conductive and convective heat transfer resulted in a significantly lower temperature 
(<150C) alteration assemblage (opal-CT, quartz, and several zeolite minerals) near the heat 
source (Nakata et al. 1998 [156365], p. 334). 
11.2.12.2 Scale Formation in Geothermal Reinjection 
Reinjection of geothermal water is necessary in many fields because of the need to dispose of 
produced water and maintain reservoir pressure. The precipitation of minerals can pose a serious 
problem in the reinjection of geothermal fluids. Reinjection occurs following energy extraction, 
thus the resulting geothermal fluid has been cooled and concentrated (owing to steam extraction) 
from its original, in-reservoir condition. This often results in silica concentrations exceeding 
saturation values, causing scale formation in reinjection pipelines, wells, and the receiving 
formation (Corsi 1986 [156344], pp. 839840). 
Silica behavior in geothermal environments has been studied in great detail (Bohlmann et al. 
1980 [156363]; Weres and Apps 1982 [156644]; Rimstidt and Barnes 1980 [101708]), but the 
scaling behavior of a particular geothermal fluid is still difficult to predict. This is because traces 
of contaminants can significantly affect the rate of silica polymerization and deposition 
(Mroczek and McDowell 1990 [156342], p. 1619). Additionally, quantitative data on other 
factors such as pH, temperature, and supersaturation may not be known for the conditions for 

which one desires to predict. Reduction in the ability to inject these fluids has been noticed at 
several geothermal fields (for example, Hatchobaru and Otake, Japan) (Horne 1982 [156362]; 
Itoi et al. 1984 [156347]) and is considered to be a delicate problem with reinjection (Stefnsson 
1997 [156343]). 
Otake Geothermal Field, Japan 
In an effort to understand silica precipitation in the Otake geothermal field, Japan, an extensive 
research effort was undertaken including field-scale reinjection, laboratory experiments, and 
numerical modeling. In the field, Itoi and colleagues (Itoi et al. 1987 [156346], pp. 541542; 
1989 [156345], pp. 153155) injected geothermal waters into two wells over 656 days. The 
120162C waters were extracted and cooled to temperatures between 50 and 80C to cause 
silica supersaturation ratios between 2 to 3.2, and were reinjected. Over the course of the 
experiments, the permeability of the two wells declined unsteadily to 4% and 0.35% of their 
initial values, respectively (Figure 11.2-13). Under the conditions of the injection, the volume of 
silica, if all precipitated, would have been about 170 and 196 m3 for the two wells. Borehole 
televiewer and caliper logs indicated that little of the total mass of injected silica was deposited 
in the well bores; however, the well screens were strongly fouled by silica scale. 
Of interest in the Otake geothermal field is the likely occurrence of formation sealing, over both 
gradual and punctuated temporal intervals, probably resulting from the plugging of narrow 
fracture and pore apertures. Yet, there are significant differences between this reinjection study 
and the predicted anthropogenic system at Yucca Mountain. First, supersaturation ratios at 
Yucca Mountain will only be high near the boiling front. In the field experiments at Otake, the 
supersaturation ratios were controlled by cooling the water, resulting in the entire reinjected 
volume being supersaturated with respect to silica. Supersaturation in the Yucca Mountain 
system will be controlled either by boiling off water as water approaches the drifts, or by cooling 
as water flows away from the repository below the drifts. Second, water flow rates will be much 
lower at Yucca Mountain. Flow at Otake is hydraulically saturated, and large volumes of water 
were reinjected into the wells over the test duration. Flow at Yucca Mountain will be 
hydraulically unsaturated with a flow rate many orders of magnitude less than at Otake, 
considering the spatial scale of the experiment at Otake. Permeability at Otake was dramatically 
reduced as a result of silica precipitation from injection of large (5  105 m3) volumes of water 
into each well over the test duration (Itoi et al. 1989 [156345], pp. 153155). If we assume that 
this water affects a spherical shell 50 m in diameter within the reservoir, this provides a fluid flux 
of several m/yr, which is three orders of magnitude larger than expected fluxes at Yucca 
Mountain (order of 10 mm/yr) (Flint et al. 2001 [156351], pp. 2223). 
Laboratory experiments were run to evaluate permeability changes caused by silica precipitation 
using water from the Otake geothermal field. In these experiments, geothermal water at about 
92C was run through a column (50 cm  5 cm diameter) of 2 mm aluminum beads or rock 
particles (Itoi et al. 1984 [156347] pp. 301302; 1986 [156352], p. 229). Silica was deposited 
primarily in the top 10 cm of the column. Specific deposits of silica (defined as the ratio of silica 
weight to bead weight) of less than 0.02 caused a two-orders-of-magnitude permeability 
decrease. These results were compared to the drilling of a replacement injection well next to a 
fouled well at the Hatchobaru Geothermal Field, Japan. The new well had the same injectability 
as the original old well, indicating that silica precipitation is occurring near the source. 

Reinjection at New Zealand Geothermal Fields 
A variety of studies of silica precipitation from geothermal waters from the Taupo Volcanic 
Zone has been performed (Mroczek and Reeves 1994 [156360]; Mroczek and McDowell 1990 
[156342]; Mroczek 1994 [154621]; Carroll et al. 1998 [124275]). Field experiments conducted 
at several of the geothermal fields in this area measured scale deposition rates under different 
process conditions in pipes, open channels, and gravel beds to determine the conditions under 
which the scaling could be tolerated in piping, wells, and reinjection aquifers. Data were 
collected at the Rotokawa well RK4, Ohaaki wells BR20, BR22, BR11, and Wairakei well 61. 
Geothermal fluid, being pretreated to the proper initial condition by cooling, aeration, and 
flashing, was then flowed through packed beds or pipes, and the amount of silica deposited was 
measured, generally by weighing. 
The main conclusions drawn from the field studies are: (1) silica deposition occurs prior to the 
beginning of polymerization when all the silica is present as monomers; (2) only a small fraction 
of total silica deposits as scale, such that the total silica concentration is relatively unchanged; (3) 
deposition remains constant or increases with increasing fluid residence time; (4) deposition rates 
from lower-temperature, low-silica and poorly buffered Wairakei water exposed to the 
atmosphere were up to more than an order of magnitude higher than unaerated water; however, 
aeration had little effect on Ohaaki BR22 water; (5) nucleation appears slow in nonhomogeneous 
nucleation systems, but once started, scale will continue to grow rapidly; (6) scale appeared to be 
denser and deposition rates lower at higher velocities; (7) deposition onto clean iron pipes 
decreases after some time, presumed to be after the surface is uniformly coated with silica, and 
deposits formed at higher temperature were tougher and more adherent than those formed at 
lower temperatures. 
11.2.12.3 Application to Yucca Mountain 
The potential effects of fracture mineralization on fluid flow have already been discussed in the 
section on boiling. Other potential impacts to consider include alteration and precipitation of 
hydrothermal minerals that would impact the sorptive properties of the Yucca Mountain 
unsaturated zone and affect transport of fluids below the drift areas. 
Below the repository, regions containing zeolites are present. Zeolites are hydrous secondary 
minerals that are well known for having sorptive properties. Heating of the zeolites may cause 
dehydration or transformation to phases (such as the less-sorptive zeolite analcime) that will 
reduce the sorptive capacity of the subrepository horizons. The zeolites at Yucca Mountain were 
formed by diagenetic alteration of vitric tuff in response to a magmatically induced thermal pulse 
(Broxton et al. 1987 [102004], pp. 107108). The increase in temperature caused by waste 
emplacement could result in the formation of additional zeolites in the vitric tuffs below the 
repository horizon. Because of heat conduction, the temperatures will decrease with distance 
from the repository. Many dissolved components, such as silica, decrease in solubility as the 
temperature decreases. However, the precipitation of amorphous silica below the repository is 
expected to be limited in extent (BSC 2004 [167974], Sections 6.6.2.3.2, 6.7.5.2, and 6.8.5.4). 

11.2.13 General Observations and Conclusions 
Geothermal systems illustrate a variety of THC processes that are relevant to Yucca Mountain. 
They include advective and conductive heating, fracture-dominated fluid flow, chemical 
transport, boiling and dryout, condensation, and mineral alteration, dissolution, and precipitation. 
Some of the more pertinent observations made regarding these processes are listed below: 
Fluid flow in low-permeability rocks (such as the welded ash flow tuffs found at Yucca 
Mountain) is controlled by interconnected fractures. Alteration in low-permeability rocks 
is typically focused along fracture flow pathways. Only a small portion of the fracture 
volume needs to be sealed in order to retard fluid flow effectively. At Yucca Mountain, 
fluid flow and low-temperature water-rock interaction over the past 10 m.y. have resulted 
in the precipitation of minor amounts of opal and calcite on fracture and lithophysal 
cavity surfaces. More extensive water-rock interaction may occur in fractures in the near 
field if a heat pipe is generated after waste emplacement occurs. 
The main sealing minerals in geothermal systems are silica polymorphs (amorphous 
silica, chalcedony, cristobalite, and quartz), swelling clays (smectite and saponite), 
zeolites, anhydrite, and calcite. These minerals typically form an impermeable cap above 
the high-temperature geothermal reservoir where convective fluid flow occurs. The main 
minerals predicted to precipitate in the near field of the potential Yucca Mountain 
repository are amorphous silica and calcite. 
Sealing can occur in geothermal systems over a relatively short time frame (days to 
years). Precipitation of minerals can be triggered by a variety of processes, including 
boiling, water-rock interaction, heating and cooling of fluids, and fluid mixing. Mineral 
solubilities, reaction rate kinetics, and the flux and chemistry of circulating fluids control 
the rates and volumes of mineralization. The unsaturated conditions, lower temperatures, 
and much lower fluid flow rates predicted for the Yucca Mountain system in comparison 
to geothermal systems, should result in less extensive water-rock interaction than is 
observed in geothermal systems. Current THC models for Yucca Mountain (BSC 2004 
[167974], Section 6.8.5.4, Figures 6.8.406.8.42) predict that near-field reductions (4- 
7%) in fracture porosity resulting from precipitation of amorphous silica and calcite can 
lead to significant (one to three orders of magnitude) localized reductions in fracture 
permeability, resulting in lower predicted fluid flux into the emplacement drifts. 
Fracturing and sealing occur episodically in geothermal systems. Different generations 
of fracture mineralization indicate that there are multiple pulses of fluid flow, recording 
distinct temperature conditions and fluid compositions, throughout the lifespan of a 
geothermal system. Most mineralization at Yucca Mountain is predicted to occur soon 
after waste emplacement (1,000 to 2,000 years), when temperatures would reach boiling 
(for the higher-temperature operating mode) above the emplacement drifts. The absence 
of boiling for the lower-temperature operating mode would result in reduced amounts of 
fracture mineralization. 
The effects of processes such as boiling, condensation, dissolution, and precipitation for 
the higher-temperature operating mode for Yucca Mountain will be most significant in 

the near-field environment. Changes in permeability and porosity are expected to be 
relatively minor at the mountain scale, where thermal perturbations will be reduced; this 
also applies to the lower-temperature (sub-boiling) design. Relatively small changes in 
zeolite concentrations (<1% volume) were predicted within the nonwelded zeolitebearing 
Paintbrush and Calico Hills tuffs resulting from precipitation and dissolution 
reactions (BSC 2001 [155950], Section 3.3.6.3.2), and, thus, the sorptive properties of the 
potential repository would not be greatly modified. 
TH reservoir models have been effectively used for many producing geothermal systems 
to model initial state conditions and to predict changes in field performance resulting 
from production and injection activities. The successful use of these models provides 
confidence that they can be applied to predict fluid and heat flow at Yucca Mountain. 
Incorporation of chemical reactions and transport processes into these models has not 
been done extensively for geothermal systems. 
THC coupled-process modeling approaches used at Yucca Mountain can be validated by 
applying the technique to a number of well-constrained geothermal systems. A 
simplified model of a portion of the Yellowstone geothermal system was constructed to 
test the ability of the TOUGHREACT code to predict the alteration mineral assemblage 
given the initial rock mineralogy and observed fluid chemistry and temperatures (Dobson 
et al. 2003 [168273]). Preliminary simulations involving the Biscuit Basin perlitic 
rhyolite unit were consistent with the observed alteration of rhyolitic glass to form 
celadonite. 
Detailed reviews of selected geothermal systems improve understanding of fluid flow in 
fractured rocks, the timing and episodicity of alteration, and the effects of alteration on 
permeability. A number of geothermal systems hosted by rhyolitic ash flow tuffs such as Long 
Valley, California (Mariner and Willey 1976 [156811]; Flexser 1991 [156815]; Sorey et al. 1991 
[156816]), and Baca, New Mexico (Hulen and Nielson 1986 [156813]; White 1986 [156814]; 
Goff et al. 1992 [156808]; Goff and Gardner (1994 [156812]) have been the subject of earlier 
studies of core and fluid samples. Further examination of the zonation, distribution, and ages of 
alteration minerals, and porosity and permeability variations as a function of degree of welding, 
alteration, and fracture intensity, can serve as additional validation of THC models. To construct 
an integrated time/temperature/fluid composition/alteration history of these systems, it may be 
necessary to supplement existing information with new fluid inclusion data, permeability and 
porosity measurements, and radiometric age determinations. In the next section, a detailed 
review of the Yellowstone geothermal system is presented, with attention focused on silica 
mineralization and sealing, geochemical modeling, and their relevance to the Yucca Mountain 
system. 
11.3 YELLOWSTONE AS A NATURAL ANALOGUE FOR THC PROCESSES 
11.3.1 Introduction and Objectives 
The Yellowstone geothermal system has previously been utilized as a natural analogue for Yucca 
Mountain (CRWMS M&O 2000 [141407]). During the course of the current review of 
geothermal natural analogues (Section 11.2), Yellowstone was identified as a particularly useful 

example of a number of important THC processes of interest. The Yellowstone geothermal 
system has reservoir rocks very similar in mineralogy and chemistry to rhyolitic tuffs found at 
Yucca Mountain. Important processes such as boiling, mineral dissolution and precipitation, and 
changes in permeability caused by self-sealing have been documented at Yellowstone. An added 
benefit is the availability of rock and fluid samples collected from surface and subsurface 
locations (see Section 11.3.5). In addition to reviewing the existing body of literature on 
Yellowstone, permeability and porosity variations were also studied in two Yellowstone 
coreholes (Dobson et al. 2001 [154503]; [154547]; Dobson et al. 2003 [168270]). These 
observations were then used to constrain preliminary simulations of water-rock interaction at the 
Yellowstone geothermal system (Dobson et al. 2003 [168273]). 
In this section, several aspects of the Yellowstone geothermal system are reviewed in the context 
of coupled THC processes. These include: (1) observed changes in surface thermal feature 
chemistry and associated mineralization; (2) a study of the role of lithology and alteration on 
porosity and permeability in the reservoir rocks of the Yellowstone geothermal system; and (3) 
the validation of water-rock geochemical modeling through study of fluid chemistry and 
alteration mineral assemblages. The objective of this review is to illustrate how such processes 
can affect fluid flow behavior, and ultimately, apply these observations to the potential Yucca 
Mountain repository. 
11.3.2 Introduction to the Yellowstone Geothermal System 
Yellowstone National Park is the site of one of the largest active geothermal systems in the world 
(Figure 11.3-1), with hundreds of thermal features located both within and outside of the 0.6 Ma 
Yellowstone caldera (Fournier 1989 [156245], p. 16). The Yellowstone volcanic center has had 
three major caldera-forming ash flow tuff eruptions (at 2.0, 1.3, and 0.6 Ma); these eruptions 
have been interspersed with lesser eruptions of lavas and tuffs that are predominantly rhyolitic in 
composition (Hildreth et al. 1984 [156248], pp. 83398350; Christiansen 2001 [156739], pp. 
G11G68). While the most recent eruptive activity at Yellowstone occurred at about 70 ka, the 
high heat flow at Yellowstone suggests that magma currently underlies much of the Yellowstone 
caldera. 
Studies of the active hydrothermal features at Yellowstone suggest that the geothermal system 
consists of two distinct reservoirs: a liquid-dominated reservoir in the western portion of the 
caldera and a steam-dominated system in the eastern portion (Fournier 1989 [156245], p. 17). 
The chemistry of chloride-rich waters sampled from the Upper, Midway, Lower, West Thumb, 
Shoshone, and Norris Geyser Basins indicates that the reservoirs feeding these features have 
temperatures ranging from 180 to 325C, with a fairly dilute (<2,000 ppm TDS) neutral chloride 
brine (Fournier 1989 [156245], pp. 1820; Fournier et al. 1992 [156247], p. 1289). 
The U. S. Geological Survey drilled 13 research core holes in Yellowstone National Park in 
19671968, with the objectives of determining the temperature and pressure gradients and 
describing the nature of water-rock interaction at the Yellowstone geothermal system (White et 
al. 1975 [154530], Table 3, pp. 12). These holes range in depth from 66332 m, with most 
holes having depths of 150 m. Pressure and temperature measurements were made as the drilling 
progressed, with additional pressure and temperature surveys conducted in most wells after 
completion. The highest measured temperature (237.5C) was obtained at the bottom of the 

deepest hole; most of the wells have maximum temperatures of 165200C. Continuous core 
samples collected from each well were subsequently subjected to detailed mineralogic study to 
characterize the primary lithologies and the alteration phases formed by water-rock interaction. 
11.3.3 Silica Mineralization at Porkchop Geyser 
Numerous studies at Yellowstone have focused on hydrothermal silica sealing and its effect on 
permeability (Keith et al. 1978 [106316]; Sturchio et al. 1986 [156253]; Fournier et al. 1991 
[156246]). Mechanisms for silica precipitation include: (1) cooling of silica-saturated waters; (2) 
mixing of fluids with different chemistries and temperatures; and (3) boiling. Silica sinter is a 
commonly observed trait of many of the thermal features at Yellowstone National Park. 
Porkchop Geyser, located in the Norris Geyser Basin, provides a natural laboratory to evaluate 
rapid changes in permeability due to amorphous silica sealing caused by boiling (Fournier et al. 
1991 [156246] pp. 11181119). 
Porkchop Geyser has been the subject of chemical monitoring for over 50 years. Early changes 
in flow characteristics were attributed to the 1959 magnitude 7.5 Hebgen Lake earthquake, 
which caused many observed changes in thermal activity throughout Yellowstone (Marler 1964 
[156249]). Since the earthquake, flow properties of this thermal feature have evolved from a 
quiescent hot spring (19601971) to an infrequently geysering pool (19711985) to a perpetually 
spouting geyser (19851989). The geyser eruption height increased significantly (from 69 m to 
2030 m) immediately preceding a small hydrothermal eruption that occurred on September 5, 
1989. This eruption consisted of a single blast that formed a crater measuring 13.9 by 11.7 m 
(Figure 11.3-2), surrounded by ejecta blocks of siliceous sinter (Fournier et al. 1991 [156246], 
p. 1115). Some of the ejected sinter blocks (Figure 11.3-3) had coatings (up to 1 cm thick) of 
clear to translucent botryoidal masses of silica; a few of these masses were still pliable shortly 
after the eruption, suggesting that the amorphous silica formed as a colloidal coating on 
subsurface cavity walls just prior to eruption. 
The observed temporal changes in flow properties were accompanied by systematic changes in 
the chemistry of the Porkchop Geyser fluids (Figure 11.3-4). Sodium-potassium-calcium (NKC) 
geothermometry temperatures increase with time from 214C in 1961 up to 273C a few months 
prior to the hydrothermal eruption (Fournier et al. 1991 [156246], Figure 4, Table 1, pp. 1116 
1118). These increases in calculated reservoir temperatures are accompanied by increasing silica 
concentrations (from 420 ppm in 1961 to 741 ppm in 1989). No colloidal silica was either 
detected by observation (via the presence of an opalescent color to the water) or by analysis 
(comparison of colorimetric and total silica measurements) prior to the time that the thermal 
feature became a perpetual geyser. While the lack of standing water precluded such 
measurements during the time when Porkchop Geyser was a perpetually spouting feature (1985 
to 1989), the presence of colloidal silica during this time can be inferred from posteruption 
conditions. The boiling water partially filling the eruption crater has an opalescent color, and 
18% of the total silica measured on January, 1990, consisted of colloidal silica. 
The above observations were interpreted by Fournier et al. (1991 [156246], p. 11181120) to 
reflect changes in the upflow water chemistry and in the amount of boiling occurring during 
upflow. The increasing NKC geothermometry temperatures since 1961 suggest that the waters 
for this feature were derived from an increasingly hotter source with time. The higher silica 

contents are probably caused by both the higher fluid source temperatures and the increased 
amounts of boiling occurring during upflow. Deposition of amorphous silica triggered by the 
increased silica concentrations would result in decreased permeability within the flow channels 
and contribute to increased pressures below constrictions present in the fluid pathways. Fluid 
overpressures probably led to the rupturing of the sinter throttle at the mouth of the geyser, 
resulting in a rapid depressurization of the shallow part of the geyser plumbing, causing 
immediate boiling that triggered the hydrothermal explosion. 
11.3.3.1 Comparison with Yucca Mountain 
While the amounts of heat and fluid flow at Yellowstone are orders of magnitude greater than 
those expected for Yucca Mountain, the link between boiling, increased silica concentrations, 
and resulting precipitation of amorphous silica can still be applied to the Yucca Mountain 
system. Under the higher-temperature operating mode, where boiling temperatures are predicted 
to persist in the near-drift environment for 1,000 to 2,000 years, dissolved solids will precipitate 
as dryout occurs (BSC 2004 [167974], Sections 6.8.5.3 and 6.8.5.4, Figures 6.8-11, 6.8.44- 
6.8.46). The amount and composition of minerals precipitated by dryout depends in part on the 
flux of fluids into the dryout front and the composition of these fluids. Development of a heat 
pipe above the emplacement drifts at Yucca Mountain could lead to increased fluid flow and 
chemical transport into the dryout area. Measured concentrations of dissolved silica in heated 
waters collected from hydrology boreholes around the Yucca Mountain DST are up to four times 
those of unheated porewater compositions (BSC 2004 [167974], Table 7.1-3). While the DST 
fluid concentrations (up to 285 ppm SiO2) are still significantly lower than those observed for 
Porkchop Geyser (741 ppm), they demonstrate how heating can lead to increased silica 
concentration that ultimately results in the precipitation of amorphous silica. Sustained reflux of 
silica-bearing fluids into fractures within the dryout zone at Yucca Mountain could ultimately 
lead to plugging of high-permeability flow channels, thus changing fluid flow paths in the neardrift 
area. These changes could persist with time, so that when the near-drift area cools below 
boiling temperatures, seepage into the drifts is restricted to flow along unsealed fractures with 
larger apertures. Because of the unsaturated nature of the Yucca Mountain system, fluid 
overpressures will not develop, and, thus, hydrothermal explosions such as the one observed at 
Porkchop Geyser do not need to be considered for Yucca Mountain. 
11.3.4 Silica Sealing at Yellowstone 
Mineral dissolution and precipitation and associated changes in permeability resulting from 
water-rock interaction have been observed in a number of geothermal systems (Grindley and 
Browne 1976 [154531]; Fournier 1985 [154614]). One of the best examples of self-sealing is 
recorded in the subsurface hydrothermal mineralogy observed in Yellowstone drill cores (White 
et al. 1975 [154530], pp. 2022). Keith et al. (1978 [106316], pp. A24A25) present a summary 
of hydrothermal alteration studies conducted on cores from two scientific drilling locations in the 
northern part of the Upper Geyser Basin, located about 3 km northwest of Old Faithful Geyser. 
These drill holes are separated by only 130 m and have similar stratigraphies, but have 
significantly different temperature and pressure profiles. Keith et al. (1978 [106316], pp. A24 
A25) interpret the contrasts in wellhead pressures at equivalent depths to indicate horizontal selfsealing 
resulting from hydrothermal alteration. Vertical pressure gradients found in the wells 
also suggest the presence of low-permeability flow barriers. 

To determine the nature and extent of self-sealing at Yellowstone, lithologic and alteration 
descriptions, matrix permeability measurements, and fracture and vein characterization were 
conducted on core samples from the Y-5 and Y-8 boreholes (Dobson et al. 2001 [154547], pp. 
283287; [154503]). The Y-5 well, located in the Midway Geyser Basin, penetrates a thick 
section of Lava Creek rhyolite ash flow tuff that varies in texture from nonwelded to densely 
welded, with vapor-phase cavities present in some sections (Figure 11.3-5). The Y-8 core hole, 
located in the Upper Geyser Basin, has a more complex stratigraphy, consisting of volcaniclastic 
sediments, perlitic rhyolitic lava, and nonwelded pumiceous ash flow tuff (Figure 11.3-6). Both 
of these wells have an upper conductive gradient that changes into a nearly isothermal (~170C) 
section at depths of 5580 m (Figure 11.3-7). Detailed descriptions of the alteration mineralogy 
of both of these cores are presented in Keith et al. (1978 [106316], Figure 4, pp. A13A24) and 
Keith and Muffler (1978 [152663], Figure 2, pp. 392398). 
Variations in porosity and permeability (Figures 11.3-8 and 11.3-9) correlate with lithology, 
degree of welding, and alteration (Dobson et al. 2001 [154547], pp. 285286; [154503]). Perlitic 
rhyolitic lava samples have low porosities (mean of 10%) and very low matrix permeability 
values, as most samples were below the 0.1 millidarcy (md) detection limit of the 
minipermeameter. Volcaniclastic sediments typically have intermediate porosities (mean of 
27%) and high permeabilities (>100 md), but silicified sediments have much lower 
permeabilities and a 50% reduction in porosity. Nonwelded pumiceous tuff samples from the Y- 
8 well have very high porosities (mean of 53%) and intermediate permeability values that range 
from 0.5478.1 md (median value of 5.4 md). Nonwelded to weakly welded ash flow tuffs from 
the Y-5 well have intermediate porosities (mean of 34%) and permeabilities ranging from 5.57 
1190 md (median value of 177 md). Moderately to densely welded tuffs have greatly reduced 
porosities (mean of 15%) and very low matrix permeabilities (0.00218.5 md, with a median 
value of <0.1 md). The large difference in matrix permeability between nonwelded and densely 
welded tuffs is similar to that reported by Winograd (1971 [156254], Figure 5, p. 999). 
Fractures observed in the Yellowstone core samples have a number of different origins, relating 
to the cooling of volcanic units, regional volcanic and tectonic processes, and hydrothermal 
activity. The distribution of veins and fractures in the Yellowstone cores (Figures 11.3-10 and 
11.3-11) is correlated with texture and lithology (Dobson et al. 2001 [154547], pp. 286287; 
[154503]). Veins and fractures are most abundant in the more densely welded tuffs, which have 
an average of about 5 fracture/vein features per meter of core over the studied interval (17.7 
84.7 m for the Y-5 core). These fractures range from planar to irregular to hackly in form and 
have dips ranging from subhorizontal to near-vertical, and many of the fractures probably 
originated as joints formed during cooling of the tuff after emplacement (Winograd 1971 
[156254], Figure 4, p. 997). The above correlation between fracture frequency and degree of 
welding is consistent with the observed fracture distribution at Yucca Mountain, where fractures 
are more abundant in welded Topopah Spring tuff (0.814.36 fractures/m) than in the nonwelded 
Paintbrush tuff (0.460.97 fractures/m) (BSC 2003 [161773], Table 7). 
In the Y-8 core, the perlitic rhyolitic lava has abundant, randomly oriented veinlets and 
microveinlets that form a stockwork configuration. In contrast, the volcaniclastic sediments and 
nonwelded to weakly welded tuffs have very few veins and fractures. Fracture and vein 
apertures range from <0.5 mm up to 20 mm. While most of the fractures observed in the core 
samples appear to be effectively sealed by mineralization, the presence of euhedral secondary 

mineral phases such as mordenite, analcime, and bladed calcite indicates that some fractures, 
veins, and vugs were open to fluid flow and may still serve as open pathways. 
Several zones of hydrothermal breccia (Figure 11.3-12) were observed in the cores (Dobson et 
al. 2001 [154547]; [154503]). The breccia zones typically consist of a discrete, near-vertical 
vein that broadens upward and contains angular clasts of wall rock up to 5 cm in diameter that 
form a jigsaw texture in a brownish-red silica, montmorillonite, and Fe-oxide/hydroxide matrix. 
These breccias, found within the densely welded tuff, represent transient conduits of high fluid 
flow that are formed by the explosive release of overpressure in the underlying geothermal 
reservoir, and are subsequently sealed by supersaturated geothermal fluids (Grindley and Browne 
1976 [154531], pp. 379381). Numerous hydrothermal explosion craters have been identified at 
Yellowstone (Muffler et al. 1971 [156250], pp. 723724), and a small hydrothermal eruption 
was observed in 1989 at Porkchop Geyser (Fournier et al. 1991 [156246], pp. 11141116). This 
type of eruption will not occur at Yucca Mountain, because the prevailing unsaturated conditions 
will preclude the pressure buildup required for this to occur. 
Most fluid flow in the Yellowstone geothermal system is associated with high-permeability 
features, namely the matrix of high-permeability lithologies and open veins and fractures. While 
the initial permeability distribution is controlled by lithology, subsequent hydrothermal alteration 
has clearly modified both matrix and fracture permeability (Figure 11.3-13). Hydrothermal 
alteration resulted in the reduction of matrix permeability and focusing of flow along fractures, 
where multiple pulses of fluid flow and self-sealing have occurred. 
Hydrothermal self-sealing appears to have generated the existing permeability barrier that 
delineates the top of the convecting geothermal system at Yellowstone. A steep increase in 
wellhead pressure observed during drilling between 49.7 (0.55 barg [bar gauge]) and 55.2 m (2.0 
barg) in the Y-8 well suggests that a major low-permeability zone is located between these 
depths within the lower part of the volcaniclastic section (White et al. 1975 [154530], Table 5, 
pp. 1822). The fluid responsible for this pressure increase probably entered the borehole 
immediately below the low-permeability silicified interval at 51.754.0 m and above the contact 
with the perlitic rhyolitic lava at 55.2 m. This depth also marks the transition between a steep 
conductive thermal gradient observed above and a near-isothermal section that extends to the 
well bottom. The presence of bladed calcite near this interval and elevated d18O values of 
hydrothermal quartz suggest that the silica seal may have formed in response to transient boiling 
events associated with depressurization (Sturchio et al. 1990 [154524], Table 1, pp. 3034). 
Silicification is not the only type of hydrothermal alteration that has affected fluid flow in the 
Yellowstone geothermal system. The presence of abundant clay minerals (montmorillonite and 
celadonite) and zeolites (clinoptilolite, mordenite, and analcime) as replacement minerals and in 
void spaces also probably reduced the matrix permeability for all of the rock units studied. 
Dissolution and replacement of obsidian likely led to localized increases in porosity and 
permeability, especially within the volcaniclastic sediments. 
Hydrothermal sealing can occur fairly rapidly. Most of the USGS core holes at Yellowstone 
were partially or completely plugged by mineral precipitation within 25 years of having been 
drilled (Fournier et al. 1993 [154527], p. 33). However, the timing and duration of the 
mineralization observed in the Y-5 and Y-8 cores are not well constrained. Uranium-thorium 

disequilibrium dating of Biscuit Basin rhyolite samples from the Y-8 core (Sturchio et al. 1987 
[154525], pp. 20292030) suggests that uranium was mobilized and added to the rock around 19 
ka. Subsequent hydrothermal alteration that decreased permeability (and, thus, ended uranium 
mobility) in this unit is more recent. A radium disequilibrium study of hot spring waters at 
Yellowstone (Clark and Turekian 1990 [156780], p. 179) suggests that the mean water-rock 
reaction time (involving congruent rock dissolution and release of radium) in the hightemperature 
reservoir is 540 years, with a maximum calculated reaction time of 1,150 years. 
The presence of multiphase veining in the Yellowstone cores suggests that there have been 
multiple episodes of fluid flow and self-sealing. A commonly observed vein assemblage for the 
perlitic rhyolitic lava is an outer band of celadonite, followed by chalcedony, and with most 
recent precipitation of mordenite. The sequential deposition of these phases indicates that there 
were progressive changes in fluid chemistry and/or temperature with time that resulted in this 
paragenetic sequence. 
11.3.4.1 Comparison with Yucca Mountain 
These observations from the Yellowstone geothermal system can be used to evaluate the coupled 
THC models developed for Yucca Mountain to predict whether, and in what time scale, 
permeability changes resulting from water-rock interaction could cause self-sealing at Yucca 
Mountain. While the Yellowstone system and the Yucca Mountain repository share many of the 
same THC processes, the effects of the processes are expected to differ significantly because of 
large differences in scale between the two systems, with much less extensive water-rock 
interaction predicted for the Yucca Mountain repository (Table 11.3-1). 
Sturchio et al. (1987 [154525], p. 2029) estimate a conservative formational velocity of 1,500 
m/yr (4.8  10-5 m/s) for the liquid-dominated, convecting Yellowstone geothermal system, 
about four to five orders of magnitude higher than those predicted for Yucca Mountain. 
Significantly higher fluid flow velocities occur along fractures, as evidenced by the high fluid 
discharge rates observed at many of the hot springs and geysers at Yellowstone. The initial heat 
flux value (67.7 kW/acre or 16.7 W/m2) estimated for the higher-temperature operating mode at 
Yucca Mountain (BSC 2001 [155950], Section 3.3.5.4) is about one-third the calculated value 
(46 W/m2) for the Firehole River drainage basin, where the Y-5 and Y-8 coreholes are located 
(Christiansen 2001 [156739], p. G52). However, the heat flux for Yucca Mountain will decline 
steadily with time as radioactive decay progresses, so that elevated temperatures at Yucca 
Mountain will not be sustained in the near-field environment beyond several thousand years. 
The dissolution, transport, and precipitation of silica are highly dependent on system 
temperature, mineralogy, and liquid flux rate, as well as on whether boiling occurs. Rates of 
silica dissolution and equilibrium silica concentrations in geothermal fluids at Yellowstone are 
significantly higher than those predicted for Yucca Mountain because of the higher temperatures 
(170 to 240C) encountered in the Yellowstone system (White et al. 1975 [154530], Table 3). 
Downhole water samples from the Y-7 and Y-8 wells have silica concentrations of 364 and 290 
mg/L, respectively (Sturchio et al. 1989 [154529], p. 1028), more than three times greater than 
those predicted for the Yucca Mountain system (Kneafsey et al. 2001 [154460], Table 1) and 
slightly higher than the maximum measured value (285 ppm) of waters collected from highertemperature 
intervals in the Drift-Scale Test (BSC 2004 [167974], Table 7.1-3). The rate of 

silica precipitation and concomitant permeability reduction depends not only on the rate of fluid 
flow, but also on processes such as boiling, cooling, and fluid mixing that result in silica 
supersaturation and subsequent mineralization. The presence of discrete zones of silicification at 
Yellowstone suggests that the processes controlling mineralization are restricted both spatially 
and temporally. 
11.3.5 Geochemical Modeling at Yellowstone 
Meijer (1987 [101345]) reviewed four active hydrothermal systems (Newberry, Long Valley, 
Valles, and Yellowstone) hosted in tuffaceous rocks within the U.S. to select the system that best 
reflects the predicted geochemical and hydrologic behavior of the Yucca Mountain repository. 
Meijer (1987 [101345], p. 7) developed the following screening criteria: 
Host rocks are tuffaceous with zeolitic alteration 
Presence of an active hydrothermal system 
Availability of core samples with characterized subsurface alteration mineralogy. 
Availability of chemical analyses of thermal waters 
Availability of geologic and hydrologic data. 
Based on these criteria, Meijer (1987 [101345], p. 10) selected the Yellowstone geothermal 
system as the best analogue case for Yucca Mountain. 
Detailed studies of the downhole mineralogy at Yellowstone (e.g., Honda and Muffler 1970 
[106045]; Keith et al. 1978 [106316]; Keith and Muffler 1978 [152663]; Bargar et al. 1981 
[156244]; Bargar and Beeson 1984 [156241]; 1985 [156243]) show that a variety of secondary 
minerals are present. The observed hydrothermal mineralization includes the following phases: 
silica polymorphs (quartz, opal-CT, chalcedony, a-cristobalite), zeolites (clinoptilolite, 
mordenite, analcime, laumontite, heulandite, dachiardite), sheet silicates (montmorillonite, illite, 
chlorite, celadonite, kaolinite, lepidolite), carbonates (calcite, siderite, rhodochrosite), Fe-Mn 
oxides/hydroxides, pyrite, fluorite, adularia, albite, and minor accessory phases. The distribution 
and abundance of these minerals appears to be controlled by fluid and rock compositions and 
temperature. 
Several thermal water compositions have been identified for the Yellowstone system on the basis 
of fluid samples collected from surface features and wells (Fournier 1989 [156245], pp. 1820). 
Deep thermal waters have low sulfate and high chloride contents, and are near-neutral to slightly 
alkaline. Steam condensate waters have low chloride and high sulfate contents, and are acidic. 
Meteoric waters have low TDS contents and are similar to the waters currently found at Yucca 
Mountain. 
Meijer (1987 [101345]) used reported fluid compositions and the EQ3/6 geochemical codes 
(Wolery 1979 [156741]) to calculate mineral assemblages for a fixed temperature. EQ3 speciates 
the dissolved constituents and calculates saturation indices for minerals, and EQ6 selects and 
precipitates phases to bring the fluids back to equilibrium conditions. A number of water 
samples were used for the geochemical modeling, including a sample with the highest silica 
content collected from Biscuit Basin that was chosen to represent the deep thermal water 
composition. Predicted mineral assemblages include silica polymorphs (chalcedony or 

cristobalite), zeolites (leonhardite or K-clinoptilolite), clays (Ca-nontronite, Ca-saponite)  
calcite and talc. These assemblages are similar to those found in the Yellowstone cores. Meijer 
attributed discrepancies between the predicted and observed mineralogies to: (1) some of the 
early-formed mineral phases not being in equilibrium with the current fluids; and (2) the use of 
inappropriate thermodynamic data for some of the mineral phases, such as zeolites. 
One important observation made from the core samples from Yellowstone is that the effects of 
hydrothermal alteration on welded devitrified tuffs for temperatures less than 170C (and where 
the geothermal fluids are not acidic) appear to be relatively minor. From this observation, Meijer 
(1987 [101345], p. 48) concluded that the thermal pulse at Yucca Mountain would have only 
minor effects on the host rocks, limited to transport and redeposition of silica and precipitation of 
clays and zeolites in fractures, cavities, and the groundmass. 
However, the key factor affecting fluid flow through the welded tuff repository horizon at Yucca 
Mountain is not the degree of alteration, but whether or not fluid flow through fractures is 
enhanced or restricted by mineral dissolution or precipitation. Meijers study (1987 [101345]) 
validates the use of geochemical modeling to predict changes in fluid and rock chemistry 
resulting from water-rock interaction, but it does not address how alteration of the Yellowstone 
cores might impact the overall permeability structure of the host rocks. 
Using the new observations of the Yellowstone geothermal system discussed in Section 11.3.4, 
Dobson et al. (2003 [168273]) utilized the TOUGHREACT reactive transport code to simulate 
the chemical effects of water-rock interaction. This study used fluid chemistry, initial rock 
mineralogy, permeability, porosity, and temperature data from the Y-8 drill hole at Yellowstone 
to predict the alteration mineralogy of the Biscuit Basin perlitic rhyolitic lava. The results of 
these simulations were in agreement with the observed alteration of rhyolitic glass to form 
celadonite. 
Comparison with Yucca Mountain 
Recent geochemical modeling for the Yucca Mountain system (BSC 2004 [167974]) employs a 
more dynamic approach that couples heat and fluid flow with geochemical transport and 
reactions and resulting changes in porosity and permeability. The TOUGHREACT simulator 
(Version 3.0) incorporates reactive chemistry and transport into the framework of the TOUGH2 
code, which simulates multiphase flow of gas and fluids together with tracer and heat transport 
through porous and fractured geologic media (Pruess 1991 [100413]). The TOUGHREACT 
code allows for the selection of kinetic or equilibrium thermodynamics to be used for mineral 
dissolution and precipitation, and it has several permeability law options available to relate 
porosity changes to changes in permeability. Simulations of fluid and heat flow and changes in 
permeability and porosity resulting from water-rock interaction were conducted for the near-drift 
region of the Yucca Mountain repository (BSC 2004 [167974]). The results of these simulations 
(conducted for thermal loads where boiling conditions persist for 1,0002,000 years) suggest that 
only small changes in permeability and porosity will occur in the near-drift area (resulting from 
the precipitation of amorphous silica and calcite), and that these changes will not have a 
significant effect on repository performance. 

The approach used for these simulations was validated through the modeling of the Yucca 
Mountain DST results (BSC 2004 [167974]) and by simulating a series of dissolution and 
precipitation experiments conducted using Topopah Spring tuff samples (Dobson et al. 2003 
[165949]). These simulations were able to successfully predict observed changes in fluid and 
gas chemistry, mineral precipitation, and associated changes in porosity and permeability over 
the duration of these experiments. 
11.3.6 Discussion and Conclusions 
The Yellowstone geothermal system serves as a natural laboratory for studying a variety of 
important THC processes. The presence of abundant thermal features, such as Porkchop Geyser, 
affords the unique opportunity to track changes in fluid chemistry and temperature over time and 
observe associated changes in mineral precipitation and reservoir permeability. Detailed studies 
of alteration mineralogy using continuous core samples from research holes drilled at 
Yellowstone reveal a detailed history of water-rock interaction. Observed variations in rock 
lithology, texture, and degree and nature of hydrothermal alteration can be used to identify 
correlations with variations in porosity and permeability. Densely welded tuffs have very low 
matrix permeabilities, but have more abundant fractures than nonwelded tuffs. A permeability 
seal encountered in the Y-8 core results from the precipitation of abundant secondary silica, 
which has greatly reduced the porosity and permeability of several intervals of volcaniclastic 
sandstones. Silica precipitation at Yellowstone results from both cooling and boiling processes, 
which serve to raise silica concentrations to above saturation levels. Geochemical modeling of 
fluid compositions has been used to successfully predict observed alteration mineral assemblages 
at Yellowstone. 
THC processes are expected to have a much smaller effect on hydrogeological properties at 
Yucca Mountain than what is observed at Yellowstone, because of unsaturated conditions, lower 
temperatures, and much lower fluid fluxes that will result in less extensive water-rock 
interaction. Development of a heat pipe above emplacement drifts at Yucca Mountain under the 
higher-temperature operating mode could lead to increased chemical reaction and transport in the 
near field. Dissolved silica concentrations in waters from boreholes around the Yucca Mountain 
DST (with water boiling under heat-pipe conditions near 95C) are up to two times those of 
ambient pore waters. Reflux and boiling of silica-bearing fluids within the near field at Yucca 
Mountain could cause fracture plugging, thus changing fluid flow paths. THC simulations 
conducted to date for the Yucca Mountain repository suggest that relatively small reductions in 
fracture porosity (4-7%) with locally larger reductions in permeability (up to 3 orders of 
magnitude) are predicted to occur in the near field as a result of amorphous silica and calcite 
precipitation (BSC 2004 [167974], Section 6.8.5.4). These predicted changes in hydrogeological 
properties should not significantly affect repository performance. 
11.4 PAIUTE RIDGEA NATURAL ANALOGUE FOR THC COUPLED 
PROCESSES 
11.4.1 Introduction 
In addition to active geothermal fields described in Sections 11.2 and 11.3, sites of fossil 
hydrothermal alteration can be useful analogues to illustrate THC processes at Yucca Mountain. 

An example of this type of natural analogue is the Paiute Ridge intrusive complex, located on the 
northeastern boundary of the Nevada Test Site (NTS), Nye County, Nevada. The complex 
consists of late Miocene basaltic dikes and sills intruded into a partially saturated Rainier Mesa 
tuff and pre-Calico Hills Formation tuffaceous host rocks. The intrusions were emplaced at an 
estimated paleodepth of about 200 m, similar to the depth planned for the Yucca Mountain 
repository. The tuffaceous host rock surrounding the intrusions was hydrothermally altered to 
varying extent, depending on the distance from the intrusions (Matyskiela 1997 [100058], pp. 
1115, 1117; Lichtner et al. 1999 [121006], p. 8). 
Natural analogues provide a means of investigating the geologic processes characteristic of the 
repository (which take place over long time spans) and validating coupled-process models used 
to predict multicomponent flow, transport, and chemical reactions. The Paiute Ridge intrusive 
complex provides useful physical and chemical data for understanding the influence of heat 
released from the repository on the tuff host rock and for THC modeling studies of the 
repository. Many other such intrusive complexes exist at the NTS and elsewhere that could 
provide an extensive data set for understanding and predicting the behavior of the Yucca 
Mountain repository. 
To model mineral alteration processes properly in the highly fractured tuff host rock, mineral 
concentrations and associated surface areas in fractures and rock matrix must be distinguished, 
and kinetic rate constantsincluding nucleation kinetics associated with the transformation of 
metastable phasesmust be known. In addition, mineral alteration may result in significant 
changes to hydrologic and transport properties such as permeability, porosity, and tortuosity of 
the repository host rock. Formation of mineral alteration zones on the scale of millimeters to 
centimeters could strongly affect the hydrologic properties of the repository host rock. As shown 
in Sections 11.2.12 and 11.3.4, fractures could become filled with silica minerals, forming a lowpermeability 
zone, or cap rock, above the repository. Alternatively, the rock matrix bordering 
fractures could become sealed, thus reducing or preventing matrix imbibition and creating fast 
pathways for infiltrating water to reach the repository. Regardless of whether mineral alteration 
in the repository host rock is considered beneficial or detrimental to the integrity of the 
repository, potential changes in physical and chemical properties of the host rock create 
significant uncertainty in performance assessment models. 
11.4.2 THC Coupled Processes Associated with a Yucca Mountain Repository 
The tuffaceous host rocks at Yucca Mountain are composed primarily of volcanic glass (absent 
in the devitrified repository host units), silica polymorphs (cristobalite, tridymite, and opal-CT), 
feldspars, zeolites, clays, and calcite (Broxton et al. 1987 [102004], Table 2). An important 
question is to ascertain whether and at what rate this metastable assemblage will revert to a 
thermodynamically stable configuration as a result of heat introduced by the repository. This 
transformation can be accelerated with the addition of heat in the presence of liquid water in an 
otherwise closed system. Uncertainty exists in estimating the impact that heat produced by the 
decaying nuclear waste will have on the repositorys performance over time (Lichtner et al. 1999 
[121006], Section 6). 
It is important to distinguish between changes in the near-field environment that take place in a 
closed system and changes resulting from fluid fluxes as a consequence of the heat generated 

from radioactive decay. For the higher-temperature operating mode, heat pipes may form above 
the repository drifts. Heat pipes (Section 11.2.4.5) are characterized by counterflow of liquid 
and vapor, with evaporation taking place at one end of the heat pipe and condensation of water 
vapor at the other, resulting in degassing of CO2 and a consequent increase in pH and purging of 
oxygen (Lichtner and Seth 1996 [100771], pp. 3-140 to 3-141). Liquid water in the condensate 
zone is relatively dilute with reduced pH and chloride concentrations compared to the ambient 
groundwater composition. Within the heat-pipe zone, temperature is near boiling at atmospheric 
pressure. Salts are expected to form in the dryout zone where complete evaporation takes place. 
High salinities could result during the rewetting phase of the dryout zone, depending on the rate 
at which liquid water comes in contact with the deposited salts. This thermal period is expected 
to last for, at most, several thousand years with relatively low liquid fluxes (Lichtner and Seth 
1996 [100771]; Hardin 1998 [100350], Figures 5-20 to 5-23; BSC 2004 [167974], Figures 6.8-11 
and 6.8-42). 
Scenarios based on THC simulations range from little or no alteration to extensive alteration with 
the formation of a silica cap above the repository and alteration of feldspars, silica polymorphs, 
and glass to zeolites and clay minerals (Hardin 1998 [100350]; Whitbeck and Glassley 1998 
[156452]; Nitao 1998 [117880]; BSC 2004 [167974]). The strong-alteration scenario could 
result in significant changes in porosity and permeability of the repository host rock that would 
affect its performance. The strong-alteration scenario represents a less probable case, because it 
assumes extremely small fracture porosity, and must occur over relatively short time spans 
(1,0002,000 years) and at relatively low temperatures (~95100C). At such low temperatures, 
nucleation kinetics can inhibit certain reactions, such as precipitation of quartz, zeolites, or clays. 
As a consequence, there exists significant uncertainty as to which reactions will actually take 
place, and if so, at what rate. Generally, silicate minerals react relatively slowly at low 
temperatures, requiring geologic time spans (>10,000 yr) before significant alteration can take 
place. 
Typically, THC calculations are performed using various forms of the dual-continuum model 
(DCM) to distinguish between fracture and matrix flow systems. The different DCMs are 
distinguished by the number of matrix nodes and their connectivity (Lichtner 2000 [156428]). 
Although fracture apertures used in DCMs can be on the order of millimeters or less, matrix 
block sizes are generally quite largeon the order of a meter to half a meter or largergoverned 
by the fracture spacing. Employing a DCM with a single matrix node of this size associated with 
each fracture node, it would be virtually impossible to describe processes taking place in the rock 
matrix at the millimeter to centimeter scale. DCMs that discretize the rock matrix are 
computationally intensive, and for this reason have not been used extensively in THC models 
applied to the Yucca Mountain repository. 
11.4.3 Criteria for Selecting an Intrusive Body as a Natural Analogue for THC Processes 
Several criteria should be satisfied for an intrusive body to serve as a natural analogue for THC 
processes at a potential Yucca Mountain repository. These criteria should include the following: 
The intrusive should be of sufficient size to produce enough heat to sustain boiling 
conditions for time spans of several thousand years. Typically, dikes and sills with 
widths greater than approximately 30 m (98 ft) will be required. 

The intrusive should be emplaced above the water table. 
Ideally, the host rock in which the intrusive is emplaced should be a volcanic tuff with 
compositional and physical properties similar to the Topopah Spring tuff at Yucca 
Mountain. 
For the Paiute Ridge intrusive complex to serve as a natural analogue for the Yucca Mountain 
repository, it is beneficial to demonstrate that the time-temperature-saturation history 
surrounding an intrusive sill is similar to that predicted for the repository. The amount of heat 
stored in the intrusion is directly proportional to its width. Typical widths in the Paiute Ridge 
intrusive complex vary from tens to hundreds of meters. The typical emplacement temperature 
of a basaltic intrusion is approximately 1,0001,200C. This temperature is considerably higher 
than the maximum temperature of about 120C estimated for the repository (BSC 2001 
[155950], Section 4.3.5.3.3), and, thus, the region very near to the intrusion cannot be expected 
to correspond to repository conditions. However, farther away from the intrusion, the 
temperature is expected to be buffered at the boiling temperature of water at atmospheric 
pressure. In this region, evaporation and condensation processes should be very similar to those 
encountered in a Yucca Mountain repository. Very likely, heat-pipe effects could have occurred 
with counter flow of liquid and vapor that were similar to those predicted to occur above and 
below the repository. 
The Paiute Ridge intrusive complex satisfies the first two criteria; however, the tuff host rock in 
which it has intruded corresponds to the Rainier Mesa tuff and not the Topopah Spring tuff (see 
below). The Rainier Mesa tuff has different chemical and physical properties compared to the 
Topopah Spring tuff. The Rainier Mesa tuff at Paiute Ridge consists of nonwelded vitric 
rhyolitic tuff (Simmons 2002 [157578], SN-LANL-SCI-215-V1, pp. 9094), whereas the 
Topopah Spring unit proposed for the repository horizon is a densely welded devitrified rhyolitic 
tuff. Because of this difference in welding, important physical properties, including fracture and 
matrix porosity and permeability and capillary properties, are different. The mineralogy is also 
differentthe Rainier Mesa tuff contains abundant glass, compared to the devitrified, 
microcrystalline matrix of the welded Topopah Spring tuff. As a consequence, chemical 
alteration, as well as wetting and drying characteristics, can be expected to be different. Even so, 
given the difficulty in finding an exact analogue to the repository host rock, the Paiute Ridge 
complex can provide answers to many questions associated with THC processes at a potential 
repository. 
11.4.4 Paiute Ridge Intrusive Complex as a Natural Analogue 
11.4.4.1 Paiute Ridge Geologic Background 
The study site is located about 40 km northeast of Yucca Mountain along the northeastern part of 
the Nevada Test Site (NTS), Nevada (Figure 11.4-1). The shallow (~200 m depth) Paiute Ridge 
complex consists of late Miocene (8.7 Ma) alkali basalt that was intruded into massive and 
bedded middle Miocene Calico Hills Formation, Paintbrush, and Timber Mountain Group tuffs 
(Byers and Barnes 1967 [101859], p. 2; Perry et al. 1998 [144335], p. 5-42). According to 
Crowe et al. (1983 [100972], p. 265), the basaltic intrusions are confined to a series of gently 
tilted fault blocks that are within a north-northwest-trending graben system of 1520 km length 

(9.312.4 mi) and 48 km (2.55 mi) wide. Most of the faulting predates the basaltic intrusion 
in this area. For further details, the reader is referred to Lichtner et al. (1999 [121006]). 
Fieldwork was conducted at Paiute Ridge for this study to characterize changes in tuff 
mineralogy, texture, and chemistry resulting from emplacement of the basaltic intrusions. While 
some variability in these properties may be attributed to pre-existing compositional, mineralogic, 
and textural zonation of the tuff (Broxton et al. 1989 [100024]; Mills et al. 1997 [157570]) and to 
low-temperature alteration associated with cooling of the ash-flow sheet and water-rock 
interaction since the tuff was deposited at 11.6 Ma, many of the changes in texture, degree of 
alteration, and whole-rock chemistry observed in the Rainier Mesa tuff samples described in 
Section 11.4 can be directly related to the proximity of these samples to the basaltic sill contact 
(Lichtner et al. 1999 [121006]; Matyskiela 1997 [100058]). Similar types of field relations were 
also observed at the Grants Ridge basalt intrusion (WoldeGabriel et al. 1999 [110071]). The 
goal of the studies described in Section 11.4 was to identify and characterize the changes in 
rhyolitic tuff host rock caused by a thermal pulse analogous to the emplacement of waste 
packages within the repository at Yucca Mountain. The field observations were then used to 
constrain numerical simulations of the Paiute Ridge system (Section 11.4.7). 
11.4.4.2 Field Studies 
A reconnaissance field study focused on examining contact relations between basaltic sills, 
dikes, and plugs, as well as the volcanic tuff country rock. The field area consists of shallowlevel 
intrusions exposed at Slanted Buttes and the valley to the east toward Carbonate Ridge 
(Lichtner et al. 1999 [121006], Section 3.1, pp. 47). Seventeen individual contact regions were 
investigated. Seven of these regions were within and around the Papoose Lake Sill, a region also 
studied by Matyskiela (1997 [100058]). Two of these regions were sites of detailed sampling. 
The field studies focused on evaluating the possible effect of basaltic intrusions on the physical, 
mineralogical, and chemical characteristics of the volcanic tuff. The volcanic tuff was examined 
in the field for changes clearly related to contact metamorphic effects. The contact relations 
were found to vary with the type and thickness of the basaltic intrusion. As a result, the 
hydrothermal alteration is more extensive adjacent to thicker sills as compared with thinner 
dikes. 
The most significant chemical and mineralogical alteration was associated with basaltic sills. 
Contact relations above, beneath, and adjacent to sills were observed on the southern flanks of 
the Slanted Buttes and at the Papoose Lake Sill. In the latter case, it was possible to observe 
volcanic tuff above the sill. Alteration was less evident adjacent to dikes compared with sills. 
This result may have been a consequence of the subvertical contact geometry, but was probably 
also affected by the relatively narrower aspect of the dikes compared with the sills, resulting in 
shorter-lived thermal events. Dikes were observed in two locations, on the southern and eastern 
flanks of Slanted Buttes, and at the Papoose Lake Sill (Figure 11.4-1, Locations B and O). A 
volcanic plug along the southern part of Slanted Buttes, which is probably the source for the 
dikes and offshoot sills at Paiute Ridge, was also examined (Figure 11.4-1, Location C). This 
plug showed the most significant physical interaction with the host tuff. The outcrop around the 
plug allowed direct observations of the contact, demonstrating plastic deformation of the tuff, 
brecciation along the contact zone, and stoping of the host tuff into the basalt flow. 

Unfortunately, the determination of the occurrence of alteration at a distance from the plug was 
not possible because of poor exposure and talus cover. 
A variety of alteration features is readily observable adjacent to contacts. These features include 
the following: 
Fusion of tuff adjacent to contact with basalt. The tuff is transformed to a dense, glassy 
erosion-resistant mass adjacent to contact with larger intrusions. 
Formation of altered anastomosing opal vein zones (Figure 11.4-2). The tuff engulfed by 
these veins is altered in color, texture, and degree of induration. The veins are found both 
as isolated features and as complex structures that completely infiltrate the rock. In 
places, the center of the veins retains open fractures that may be lined with late-stage opal 
deposits. 
Development of silica-rich veins that penetrate the tuff with relatively little obvious 
alteration of the matrix. These veins may be traceable for many meters. 
Development of pipe-like alteration features. Silica-cored pipes (circular features) cross 
the tuff, producing concentric alteration halos. These features occur on the scale of a 
meter or two. 
Milky-white opal deposits along fractures. These appear to be late-stage deposits along 
open surfaces. 
Calcite-filled fractures widespread in the basaltic sill and adjacent altered tuff (Figures 
11.4-3 and 11.4-4). 
These alteration features are common and are particularly well developed adjacent to the sills 
observed in the area. In regions lacking outcrop, altered tuff can still be identified in weathered 
rock fragments scattered as float. 
Two sites were selected for detailed sampling and assessment of the alteration geometry of the 
host tuff and the intrusive body (Table 11.4-1). These were the western limb of the Papoose 
Lake Sill (Figure 11.4-1 (Location H), Figure 11.4-5, and transect 7 of Matyskiela (1997 
[100058])) and an exposure beneath a sill exposed on the southern part of Slanted Buttes (Figure 
11.4-1, Location B). Most of the analytical work was conducted on samples collected from the 
Papoose Lake Sill and the adjacent host tuff. Hydrothermal alteration features are highlighted in 
the following sections, demonstrating significant changes above, adjacent to, and beneath the 
intrusive bodies. In all cases, the alteration effects diminish with distance from the contact. 
11.4.4.3 Contact Metamorphic and Hydrothermal Features at Paiute Ridge Intrusive 
Complex 
11.4.4.3.1 Alteration Adjacent to Papoose Lake Sill 
The Papoose Lake Sill is approximately 27 m (90 ft) wide and trends N17E at the site of detailed 
investigation (Figure 11.4-5 and Location H in Figure 11.4-1). The exposure represents a 

vertical contact with the adjacent fused (vitrophyre) Rainier Mesa tuff along the western edge of 
the sill. The base of the sill is not exposed here and the host rock above the sill is partially 
eroded. The basalt along the contact is characterized by vertically jointed plates that are about an 
inch wide and oriented parallel to it. In contrast, the basal contact between the sill and the host 
rock as observed in other locations is mainly represented by horizontally jointed narrow plates 
(e.g., the southern part of Slanted Buttes, Figure 11.4-1, Locations B and E). A few feet from the 
contact, the Papoose Lake Sill is massive. Detailed descriptions of the samples mentioned in 
Section 11.4.4.3 are found in Table 11.4-1 (Simmons 2002 [157578], SN-LANL-SCI-215-V1, 
pp. 732, 9094). 
The basalt is generally sparsely vesicular with amygdules and veinlets of calcite. A sample 
(LANL# 3547) collected along the contact is purplish gray, fine grained, and sparsely porphyritic 
with partially altered pyroxene phenocrysts. The vitrophyre zone (i.e., fused volcanic tuff) 
adjacent to the contact varies in thickness from 0.5 to 2.1 m (1.5 to 7 ft) along strike of the 
contact. It is generally black, glassy, and foliated with rare opal nodules, silica and calcite veins, 
and veinlets of reddish opaline tuff. Alteration of the tuff was investigated adjacent to the sill. 
Two vitrophyre samples (LANL# 3548 and 3549) separated by 8.2 m (27 ft) were collected 
along strike, 0.9 and 1.4 m (3 and 4.5 ft) west of the contact zone. The vitrophyre sharply 
transitions to a reddish, strongly indurated baked tuff several feet in width. A sample (LANL# 
3550) was collected about 0.5 m (1.5 ft) west of the vitrophyre. It is porphyritic with quartz and 
plagioclase phenocrysts in a partially devitrified glassy matrix. The baked tuff grades to a 
nonwelded, pinkish, and weathered tuff (LANL# 3551) that crops out about 1.7 m (5.5 ft) west 
of the vitrophyre. The pink, weathered tuff sample occurs along the eastern edge of a narrow 
anastomosing opal vein zone. The 8-cm (3-in.) wide pinkish orange opal veins (LANL# 3552 
and 3554) trend north to south parallel to the sill contact. The host tuff (LANL# 3552 and 3553) 
engulfed by the opaline vein zone is pinkish and forms resistant knobs protected by the 
surrounding veins (Figure 11.4-2). 
These anastomosing veins are found as close as 2.4 m (8 ft) from the contact. In places, the vein 
centers are open and contain white opal. The veins pinch and swell and wind around remnant 
knobs of tuff. They occur singly and as infiltrating masses. The veins are less common with 
distance from the contact and were not observed beyond about 14 m (45 ft). At 6.7 m (22 ft) west 
of the vitrophyre, the tuff (LANL# 3555) is altered. In the altered tuff, pumice clasts and the 
matrix appear to be totally silicified. In contrast, a sample collected about 0.12 m (0.4 ft) from 
LANL# 3555 is partially altered, and the pumice clasts are glassy. At 14 m (45 ft) from the 
contact, opal veins and veinlets are sparse. However, the moderately welded host tuff (LANL# 
3557) is partially altered and contains glassy pumice clasts. Silica and calcite replacements 
occur side by side in the matrix (Figure 11.4-4). 
Between 15 and 61 m (50 and 200 ft) from the contact, the nonwelded and unaltered tuff is 
friable and vitric and contains large pumice fragments. Narrow fractures contain calcite in some 
places, but no other alteration features were evident in cavities and/or vesicles (Figure 11.4-6). 
These contact relations represent the most complete record of alteration at close proximity to the 
intrusive bodies in the study area. 

11.4.4.3.2 Alteration Patterns above the Papoose Lake Sill 
Although well-preserved sections were not found above the sill, abundant evidence of pervasive 
alteration was observed in the overlying Rainier Mesa tuff. In some places, the alteration 
appeared more intense in terms of density of veining or discoloration and silicification of the 
host tuff. Several samples (LANL# 35603565) were collected above the sill between the 
western and eastern limbs, directly east of the detailed sampling section at Papoose Lake (Figure 
11.4-1, Locations I, J, K, N, O, and P; Table 11.4-1). Because of poor exposure in the western 
half of the overlying tuff, most of the samples were collected closer to the eastern limb. More 
samples (LANL# 35383545) were also collected above the Papoose Lake sill at location K, 
about 490 m (1,600 ft) northeast of the main sampling location (Location H) along the western 
limb of the sill (Figure 11.4-1). At Location K, the exposed sill is about 15 m (50 ft) wide. The 
degree of alteration is similar to Location H, represented by dense anastomosing opal veining 
that is about 7.6 m (25 ft) wide. However, unlike the sill contact with the tuff at Location H, no 
vitrophyre or fused tuff was noted near the opal veins above the sill at Location K. The Location 
K area is not completely exposed, and thus a vitrophyre zone that is obscured by talus may exist 
in this area. Although the thickness of the veined zone is unknown, it is located about 45 m (150 
ft) to the east of the exposed sill margin. The opal veins above the sill are generally oriented 
N20W, slightly different from the N-S trend noted adjacent to the sill at Location H. 
11.4.4.3.3 Alteration Patterns Beneath a Sill 
The contact zone of a sill was examined in a gully located on the SW flanks of Slanted Butte 
(Figure 11.4-1, Locations A and B). The contact relations below the sill are generally well 
exposed and alteration patterns can be observed. The basaltic sill dips about 55 to the south. 
The sill is about 7.6 m (25 ft) thick at the point of investigation. The basalt is purplish gray, 
coarsely vesicular, and includes trains of fine vesicles. Amygdules filled with calcite and opal 
are common. Large altered mafic phenocrysts are also present. The basalt along the contact 
exhibits a thin chilled margin, consisting of horizontally jointed (with respect to the sill) and 
narrowly spaced plates along the contact with the underlying tuff. In contrast, at the Papoose 
Lake Sill in the northern part of Paiute Ridge, vertically jointed plates characterize the sill 
margin. These features clearly delineate the nature of the contact between the basaltic intrusions 
and the tuff host rocks. The country rock tuff units are pre-Rainier Mesa tuff and belong to the 
Wahmonie Formation and Crater Flat Group (Table 11.4-2). Two samples (LANL# 3570 and 
3571) were collected from the contact and the top part of the sill (Figure 11.4-1, Location B). 
The pinkish tuff along the contact with the basalt does not form a foliated vitrophyre (as was 
noted at the Papoose Lake Sill in the northern part of the Paiute Ridge area), but exhibits a dense, 
coarse-grained granite-like texture, possibly as a result of slow cooling. Incipient mineral 
layering is noted within the fused tuff directly beneath the sill. About a foot beneath the contact, 
the tuff (LANL# 3572) grades from coarser to fine-grained crystalline material. This resistant 
contact zone extends for 1.21.5 m (45 ft) below the basalt. Unlike the sections sampled in the 
northern part of the Paiute Ridge area, there are at least five tuff units beneath the sill that are cut 
by a dike finger that is vertically wedged along a fault into the underlying tuff sequence. The 
fault zone is extensively altered to clay. Two tuff samples (LANL# 3573 and 3574), collected 
about 1.3 m (4.4 ft) beneath the contact, are generally nonwelded. A moderately welded, light 
gray tuff (LANL# 35753578) that contains brown and dark lithic fragments occurs about 4.6 m 
(15 ft) beneath the sill. At 6.4 m (21 ft) beneath the sill, the same unit (LANL# 3576 and 3577) 

contains multiple layers of white to reddish orange opal veins and veinlets mostly parallel to 
bedding and to lithologic contacts. 
These opal veins are of different character than those observed at the Papoose Lake Sill section. 
They consist of white siliceous cores surrounded by a discoloration halo in some places and no 
observable halo in other places. They occur parallel to the sill-tuff contact and are about an inch 
in thickness. 
These fractured veins pinch and swell along strike and mostly occur in a 0.6 m (2 ft) wide zone. 
About 1 m (3.4 ft) below the vein zone, the tuff (LANL# 3578) is nonwelded and contains no 
opal veins. A white crystal-rich tuff crops out about 11 m (35 ft) beneath the sill. It is coarse 
grained with pumice clasts and abundant feldspar, quartz, and biotite phenocrysts. On the south 
side of the dike that wedges down into the underlying tuff, the crystal-rich tuff is intruded by a 
0.120.46 m (0.41.5 ft) wide opal vein that is 4.9 m (16 ft) beneath the sill. The vein trends 
obliquely to the tuff-sill contact and is traceable for more than 30 m (100 ft). This vein strikes 
N-S and dips 65 to the east. In addition, siliceous pipes occur about 4.6 m (15 ft) below contact. 
They are well-indurated and characterized by a white core and circular reddish halo. 
11.4.5 Original Depth of Intrusions 
Paleozoic limestone, quartzite, and shale unconformably underlie middle Miocene tephra of the 
Timber Mountain and Paintbrush tuffs and older undivided tuff units at the Paiute Ridge study 
area (Byers and Barnes 1967 [101859]; Perry et al. 1998 [144335]). The Tertiary tuffs at the 
northern and southern study areas were extensively intruded by shallow late Miocene basaltic 
dikes, sills, and plugs. Based on reconstructed topography above the sills and dikes, it was 
suggested that the intrusive bodies were emplaced a few hundreds of meters from the 
paleosurface (Valentine et al. 1998 [119132], p. 5-29, Figure 5.16; Ratcliff et al. 1994 [106634], 
p. 413). This assumption is consistent with the presence of abundant vesicles along the edges of 
the sills and dikes, the localized nature of the contact metamorphic effects adjacent to the sill, 
and minimal amounts of hydrothermal alteration along the contacts (Valentine et al. 1998 
[119132], pp. 5-41 to 5-44, 5-51). 
However, based on detailed field observations of contacts between the intrusive bodies and host 
tuffs throughout the study area, it appears that the sills and dikes started at deeper levels close to 
the plugs and eroded centers and migrated up section into shallow levels away from the central 
part of the intrusive complex. For example, the sills generally branch out from major dikes and 
intruded into pre-Rainier Mesa tuff units in the southern part, whereas the Papoose Lake Sill in 
the north intruded into the Rainier Mesa tuff. This observation is corroborated by subsurface 
stratigraphic data from several drill holes (Figure 11.4-1) along the eastern part of Yucca Flats, 
which provide information about the type and thicknesses of the major tuff units deposited in the 
basin adjacent to Paiute Ridge during the Miocene (Drellack and Thompson 1990 [156446], pp. 
111). The thicknesses of the tuff units encountered in these drillholes can be used to estimate 
the original thicknesses of the corresponding units that crop out in the adjacent Paiute Ridge area 
(Figure 11.4-1; Table 11.4-2). 
According to the subsurface stratigraphic information, the major tuff units intersected in the 
upper part of the Yucca Flats drill holes consist of the Timber Mountain Group (i.e., Rainier 

Mesa tuff and Rainier Mesa tuff vitrophyre), the Lower Wahmonie Formation, and the Crater 
Flat Group in descending stratigraphic order. The Ammonia Tanks tuff at the top of the Timber 
Mountain Group, the Paintbrush Group, and the Calico Hills Formation units were not defined in 
the drill holes (Drellack and Thompson 1990 [156446]). Using the thicknesses of the different 
tuffs in the drill holes (from the surface to the top of the Rainier Mesa vitrophere unit), it is 
estimated that the late Miocene basaltic magma was intruded into a shallow environment of 
about 200 m depth. 
Information on the degree of alteration of the tuffs encountered in the drill holes can be used to 
help differentiate between alteration caused by the basaltic sills from more regional alteration 
events. According to the Yucca Flats drill hole data (Table 11.4-2), pervasive zeolitization 
(interpreted to predate the intrusion of the basaltic sills) occurs in the lower half of the subsurface 
sequences, typically below the Rainier Mesa tuff unit. The presence of zeolites (such as 
clinoptilolite and chabazite; see Table 11.4-3) in Rainier Mesa tuff samples adjacent to the sill 
contact (and above the regional zone of pervasive zeolitization) was thus attributed to 
hydrothermal alteration resulting from the sill intrusion. 
11.4.6 Laboratory Methods and Results 
Thin sections were prepared of almost all of the samples for petrographic descriptions, using 
optical and scanning electron microscopic techniques. Selected samples from the host tuff and 
basaltic sill in the Papoose Lake area were processed for bulk chemical and mineralogical 
analyses. Additional major-element glass chemistry was obtained for most of the tuffs selected 
for bulk analysis, using an electron microprobe. Most of the tuff samples selected for analysis 
were collected adjacent to the sill at Location H. 
11.4.6.1 Petrographic Results 
The mineralogical and chemical characteristics of the alteration are keys to understanding the 
conditions of hydrothermal processes. Petrographic observations identify opal and calcite 
veining associated with some of the alteration features (Simmons 2002 [157578], SN-LANLSCI-
215-V1, pp. 8994). Calcite appears rather abundant in some sections. The vitrophyre 
found adjacent to the basalt contact contains significant volcanic glass and is largely free of 
hydrous mineral alteration. Some interesting observations were made of the anastomosing veins 
from the Papoose Lake Sill locality. 
Preliminary petrographic examination of samples of Rainier Mesa tuff systematically collected at 
intervals from the contact zone to about 61 m (200 ft) west of the sill indicate variable physical 
and mineralogical alterations (Figure 11.4-1, Location H). Comparison of two tuff samples from 
above the sill collected at different distances from the sill outcrop (Figure 11.4-1, Locations K 
and N) indicated that the intensity of alteration above the sill decreases away from the sill 
margin. A light pinkish-brown tuff (LANL# 3539) collected from a 7.6 m (25 ft) wide, densely 
veined zone about 46 m (150 ft) from the western edge of a sill northeast of the Papoose Lake 
Sill is sparsely porphyritic with plagioclase, albitic sanidine, quartz, biotite, and minor amounts 
of hornblende and clinopyroxene. Secondary minerals of silica, calcite, and minor clay replaced 
the matrix. These secondary minerals also occur in cavities and along fractures as veinlets, 
aggregate crystals, and radiating spherules, ranging in width from 25105 m. At Papoose Lake 

Sill (Location H), east of the main outcrop, a number of Rainier Mesa tuff samples collected 
above the sill are strongly indurated, moderately altered, and contain similar phenocryst 
assemblages. Secondary minerals of opal, calcite, and zeolite replaced the matrix and also occur 
in cavities and fractures. Shard fragments and pumice clasts are totally replaced by secondary 
silica. 
Similar physical (e.g., color, hardness, welding, veining) and mineralogical (silica, zeolite, 
calcite) alteration patterns are noted in the basalt and host tuff samples collected from the main 
section adjacent to the Papoose Lake Sill. The basalt along the contact is fine grained, vertically 
jointed with uniformly spaced plates, purplish gray, and sparsely vesicular with minor calcite 
and/or opal amygdules. The altered basalt is porphyritic with plagioclase and sparse mafic 
minerals that are altered to reddish brown spots. The matrix is dominated with microlites and 
microcrystalline aggregates of pyroxene. Secondary calcite, silica, clays, and perhaps zeolites 
occur as veinlets and crystal aggregates in cavities and along fractures. The veinlets pinch and 
swell and range in width from 90 to 135 m. Some cavities or mineral pseudomorphs are 
partially filled with abundant microcrystalline aggregates of epidote and calcite (Figure 11.4-3). 
Three main alteration zones were identified in the tuff near the basaltic intrusion: (1) a vitrophyre 
zone immediately adjacent to the sill contact, (2) a baked zone, and (3) an altered zone 
characterized by opal veining. The host tuff adjacent to the basaltic sill contact was fused and 
transformed to a foliated, perlitic vitrophyre with opal amygdules and silica veinlets. The 
phenocryst assemblage in the vitrophyre is similar to the overlying tuff. Secondary silica 
deposits, represented by overgrowth around phenocrysts up to 27 m wide and veinlets that are 
27 m to 0.28 mm wide, are commonly noted parallel and transverse to welding fabric. Away 
from the contact, the intensity of alteration transitions from the 2.1 m (7 ft) wide vitrophyre at 
the contact to a baked interval and then to a 7.6 m (25 ft) wide zone that is characterized by 
dense, anastomosing opal veining (Figure 11.4-2). The tuff samples are sparsely porphyritic 
with variable degrees of welding. In one of the samples (LANL# 3554), the phenocrysts are 
segregated and form bands of crystals represented by quartz, plagioclase, sanidine, and minor 
biotite and hornblende. The sample is devoid of matrix, thereby creating a crystal-rich zone due 
to winnowing. The intensity of alteration and replacement of the matrix, pumice clasts, and 
phenocrysts by calcite, silica, zeolite, and clays decrease with distance from the vitrophyre 
interval. Within the altered zone, the secondary minerals generally occur as veinlets, cavity 
filling, or as aggregates within the matrix. For example, at about 13 m (43 ft) from the contact, 
the tuff is moderately welded, and the matrix replaced by calcite and silica in separate zones 
(Figure 11.4-4). In some cases, silica spherules crystallized in fractures, causing these fractures 
to be widened later by fluid flow and also narrowed by silica and calcite recrystallization along 
the walls. The sample (LANL# 3558) collected outside the altered zone contains similar 
phenocryst assemblages, but the amount of secondary silica and calcite significantly diminished. 
The cavities and vesicle walls are devoid of secondary minerals, suggesting no effect on these 
outer units furthest from the basaltic intrusion. 
Examination of selected samples from the sill and the host tuff using a scanning electron 
microscope (SEM) shows the size and textural relations of the secondary minerals. For example, 
calcite occurs in the basalt along the contact in cavities and as 100 m wide and severalmillimeter-
long veinlets in the matrix (Figure 11.4-3). Calcite and silica intergrowth is also 
noted in the matrix. Moreover, potassium-rich euhedral crystals (possibly zeolites) are also 

present in the altered basalt. Fractures in the vitrophyre adjacent to the sill are filled totally by 
zeolites that are rich in potassium and calcium. Some of these zeolite crystals are more than 10 
m long. Calcite and silica commonly occur in cavities, and in most cases, calcite postdates 
silica. Almost all of the tuffs proximal to the contact contain silica, calcite, and abundant 
zeolites in partially filled cavities and within the matrix (Table 11.4-3). However, two of the 
samples collected from 23 and 61 m (75 and 200 ft) from the sill show no alteration effects. The 
cavities and vesicles are clean and the shards show no visible signs of alteration (Figure 11.4-6). 
11.4.6.2 Mineralogical Results 
The mineralogy of selected basalt and tuff samples was identified using quantitative X-ray 
diffraction (XRD) analysis (Simmons 2002 [157578], SN-LANL-SCI-215-V1, pp. 5659). The 
samples were ground for approximately 10 minutes using acetone in a Brinkmann automated 
grinder to reduce the particle size and homogenize the sample and internal standard. The samples 
were analyzed using calibrated Siemens D-500 powder diffractometers. 
Results of the XRD analysis are given in Table 11.4-3. Consistent with the petrographic results, 
the basalt from the contact and those tuffs collected within 14 m (45 ft) from the sill contain 
abundant secondary minerals dominated by clinoptilolite (Table 11.4-3). Although petrographic 
analysis reveals calcite and silica in the basalt, smectite was the only secondary mineral 
identified by XRD analysis. Despite clay-like alteration noted petrographically in most of the 
altered tuffs, the XRD results show only variable amounts of opal, tridymite, cristobalite, 
clinoptilolite, and chabazite in the various tuff samples. 
11.4.6.3 Geochemical Results 
Aliquots of powdered samples were used for major and trace element analyses using a Rigaku 
3064 wavelength dispersive X-ray fluorescence (XRF) (Simmons 2002 [157578], SN-LANLSCI-
215-V1, pp. 63, 6976). Analysis and statistics of the unknown samples are based on a 
model that uses intensities for 21 standard rocks. To assess whether the major and trace element 
variations of the tuff samples are genetic or a result of hydrothermal alteration related to the 
basaltic intrusion, major and trace element concentrations of bulk-rock samples were plotted 
against distance from the sill (Figures 11.4-7 and 11.4-8). An average Rainier Mesa rhyolitic 
tuff composition reported by Broxton et al. (1989 [100024]) is plotted with these data for 
comparison. A discussion of the major and trace element variability and its origin is presented in 
Section 11.4.6.4. 
11.4.6.4 Discussion 
Field and analytical results suggest that the Paiute Ridge basaltic dikes and sills intruded into at 
least two different tuff units, the Rainier Mesa tuff of the Timber Mountain Group and older 
bedded tuffs from the Lower Wahmonie Formation and Crater Flat Group that mostly crop out in 
the southern part of the study area. Generally, the host tuffs in the southern part of the study area 
are thin, mostly bedded, and crop out along gullies. Those outcrops in the northern part are 
massive, nonwelded, and occur mostly along ridge tops. Most of the analytical results were 
obtained on samples collected from the Papoose Lake Sill area at Locations H, N, and K (Figure 
11.4-1). These tuffs are pinkish, sparsely porphyritic, variably welded, massive, and generally 

contain abundant pumice clasts. For example, a light pinkish-brown tuff from above a sill at 
Location K contains plagioclase (30%), quartz (32%), sanidine (38%), and minor amounts of 
biotite, hornblende, and clinopyroxene. According to Byers et al. (1976 [104639]), mafic 
phenocrysts such as hornblende, clinopyroxene, biotite, plagioclase, and Fe-Ti oxides are 
common in the upper part of the Rainier Mesa tuff, and sanidine generally contains 
cryptoperthite rims. A vitrophyre (fused tuff) and a nonwelded tuff collected at Location H 
adjacent and at 61 m (200 ft) from the Papoose Lake sill, respectively, also have similar 
phenocryst assemblages with diagnostic albitic rims on sanidine, which is a characteristic feature 
of alkali feldspars in the Rainier Mesa tuff (Byers et al. 1976 [104639], p. 42). 
Depending on proximity to the sill, variable degrees of alteration related to the intrusion are 
recorded in the tuff units. For example, the transformation of the nonwelded Rainier Mesa tuff 
to vitrophyre, hardening and discoloration resulting from baking, and the prevalence of 
anastomosing opal veins within 12 m (40 ft) of the sill are macroscopic physical modifications 
related to the sill. However, such features are not uniformly apparent at all the contacts studied 
during the field investigation. At Location H of the Papoose Lake Sill area, the 12 m (40 ft) wide 
alteration aureole adjacent to the sill progressively changes from a 2.1 m (7 ft) wide vitrophyre at 
the contact to a comparable size of baked interval, and to a 7.6 m (25 ft) wide opal veining zone. 
However, such systematic alteration is not fully developed at Location K above the sill. There, 
hardening of the tuff and a 7.6 m (25 ft) wide opal vein zone are developed 46 m (150 ft) east of 
the western edge of the sill. At Location B in the southern part of the study area, the pre-Rainier 
Mesa tuff units are exposed beneath the sill and the alteration features are different from those 
noted at Locations H and K. The tuff directly beneath the sill was transformed into a graniticlike 
granular-to-fine-grained rock, suggesting slow cooling, following the fusion of the tuff. In 
contrast, the vitrophyre observed at location H represents a fused Rainier Mesa tuff that chilled 
rapidly adjacent to the sill. The type of the stratigraphic units and the nature of the fused tuff 
along the contact (e.g., vitrophyre or granular) suggest that the level of intrusion was deeper in 
the southern part compared with those sills and dikes along the northern boundary of the basaltic 
intrusive complex. In the southern part, multiple opal veins, ranging in thickness from a few 
inches to about a foot thick are present within 6 m (20 ft) below the contact. The opal vein zone 
(=7.5 m or 25 ft wide) noted adjacent and beneath the sills at Locations B and H (Figure 11.4-1) 
represents mass silica mobilization from altered tuff within the hydrothermal aureole. Although 
other low-temperature secondary minerals are closely associated with opal, no systematic 
zonation is apparent from the effect of the basaltic intrusion. The anastomosing opal veins 
engulfed variable sizes of tuff clasts that are partially affected by these veins. Although there 
was voluminous mobilization of silica along fractures created during the basaltic intrusion, 
subsequent fluid flow was probably significantly reduced because of the impermeable opal veins. 
The alteration zone occurred at close proximity and parallel to the basaltic sill (=14 m or 45 ft), 
likely creating a barrier between the intrusion and the outer tuff units. 
Petrographic examination of samples from hydrothermal alteration zones at Locations H and K 
revealed other secondary features related to the intrusions. Silica, calcite, zeolite, and clay 
materials are present as veinlets along fractures, as clusters in cavities and matrix, and as 
overgrowths around feldspar and quartz phenocrysts. These features appear to contain abundant 
zeolite (clinoptilolite) and show precipitation layering within the veins (Figures 11.4-6a and 
11.4-9b). The figures show a tabular crystal of zeolite overgrowing a second layer of zeolite 
having a scalloped or rounded morphology. 

The presence of zeolite as multiple generations within fractures and cavities of the altered tuffs 
suggests that zeolites in addition to silica were deposited by hydrothermal alteration associated 
with the basaltic intrusion. However, older zeolitized tuffs are present in the southern part of 
Paiute Ridge and in the lower half of the subsurface units intersected in the drill holes along the 
eastern part of Yucca Flats (Table 11.4-2; Drellack and Thompson 1990 [156446], pp. 60, 64, 
66, 6869; Valentine et al. 1998 [119132], pp. 5-46, 5-55, Table 5.3). The silica and calcite 
veinlets that range in width from microns to millimeters and in length to several millimeters also 
formed during this process. The pumice clasts and the glassy matrix of the tuffs from the 
alteration zone are mostly devitrified and/or totally replaced by calcite and silica. A basalt 
sample from the contact at Location H is also moderately altered. The rock is purplish gray and 
contains clay, calcite, epidote, and silica along fractures and in cavities. 
Published Rainier Mesa tuff chemical data from the lower part of the unit (Quinlivan and Byers 
1977 [156450], Table 6; Broxton et al. 1989 [100024], Table 3) are correlative to the major and 
trace element concentrations of the tuff samples from Locations H, K, and N in the northern part 
of Paiute Ridge. This observation is also consistent with the petrographic results. Physical, 
mineralogical, and chemical variations noted in some of the Paiute Ridge samples collected from 
the hydrothermal aureole beneath, adjacent, and above the basaltic sills are attributed to the 
intrusions. 
Localized chemical variations are noted in the host tuffs adjacent to the basaltic sills. Variations 
in major and trace element contents are more pronounced in samples collected near the contact 
(Figures 11.4-7 to 11.4-8). For less mobile components such as TiO2, Al2O3, total iron, Nb, and 
Zr, little variation is observed throughout the suite of samples, with most variability occurring 
within a zone that extends 3040 feet from the sill contact. While silica appears to be mobile (as 
observed by the presence of opal veins), the actual range of observed silica concentrations for all 
of the analyzed tuff samples is fairly small (7481% SiO2, normalized to anhydrous 
compositions). Significantly more variability is observed for the more mobile alkali and alkaline 
earth elements (Na, K, Rb, Ca, Sr). Most of the variability for Na, K, and Rb occurs within 30 ft 
of the sill contact, suggesting that the original tuff compositions were modified by hydrothermal 
alteration resulting from the sill intrusion. However, the distribution of Ca (and Sr to a lesser 
degree) is much more scattered. The measured CaO concentrations of the tuff samples (ranging 
from 0.5 to 5.6% CaO, normalized to anhydrous compositions) are generally higher than the 
average Rainier Mesa rhyolitic tuff composition (0.52 wt.%) of Broxton et al. (1989 [100024], 
Table 3). The observed increase in CaO contents is in part caused by the presence of variable 
amounts of secondary calcite in the tuff samples. The calcite may originate from two separate 
events, one being the intrusion of the sill, and the other by low-temperature precipitation of 
calcite from infiltrating groundwater over millions of years. One of the samples collected about 
122 m (400 ft) above the sill at Location O (LANL# 3560) has higher Fe2O3, MgO, CaO, Sr, Zr, 
and Ba concentrations. This may reflect a difference in the bulk rock composition resulting from 
the presence of lithic fragments within the tuff (Simmons 2002 [157578], SN-LANL-SCI-215- 
V1, p. 25). 
As shown in Table 11.4-3, abundant clinoptilolite with minor chabazite formed from the 
alteration of glass within the contact aureole of the basaltic sill at Papoose Lake Sill. Hydrolysis 
of volcanic glass, resulting in higher alkalinity and increased silica and alkali ion to hydrogen 
activity ratio in pore fluids, provided the necessary environment for the formation of zeolites 

(Hay 1978 [105967], pp. 135136; Broxton et al. 1987 [102004], pp. 91, 93). Published field 
and experimental data suggest that clinoptilolite formation is favored over other zeolites, 
including chabazite in low alkalinity (pH = 79) environments (Mariner and Surdam 1970 
[156449], p. 977; Barth-Wirsching and Hller 1989 [156445], Table 5, p. 493; Sheppard 1993 
[156451], pp. 1012). The close spatial association of clinoptilolite and opal within the 
alteration aureole suggests that the anastomosing opal veins are the result of hydrothermal 
alteration of glassy matrix and pumice clasts. For example, the most altered tuffs (LANL# 3552, 
3554, and 3555) from the contact aureole contain higher silica and lower alkali contents 
(Simmons 2002 [157578], SN-LANL-SCI-215-V1, pp. 2223, 71, 9293). Smectite is absent 
from the altered tuffs. This may be related to relatively high alkali ion to hydrogen ion activity 
ratios and relatively high silica activities, which favor the crystallization of clinoptilolite over 
smectite (Barth-Wirsching and Hller 1989 [156445], Table 5, pp. 496497; Sheppard 1993 
[156451], p. 12). Moreover, the lack of smectite in the altered tuff may be attributed to the low 
Fe, Mg, and Ca contents in the altered tuff. These cations are important components for smectite 
formation. 
In summary, the field study indicates zones of hydrothermal alteration generally occurred within 
1015 m (3050 ft) of some of the larger basaltic intrusions, especially sills. In some parts of the 
contact zone, rather pervasive alteration with a zone of silica veins is observed. In other parts, 
veining is rather limited or absent. The confinement of these features to areas adjacent to 
contacts appears to demonstrate that the veining and alteration features were caused by the 
basaltic intrusions. 
11.4.7 Thermal-Hydrologic-Chemical Modeling of Hydrothermal Systems 
As mentioned in Section 11.4.3, the Paiute Ridge system meets most of the criteria established 
for serving as an appropriate analogue for THC processes that are expected to occur at the 
potential Yucca Mountain repository. The effect of a basaltic intrusion on alteration of the host 
rock in which it is emplaced and alteration of the intrusion itself was modeled using the 
computer code FLOTRAN (Lichtner 2001 [156429]). A one-dimensional geometry 
perpendicular to the intrusion was used for the simulations (Figure 11.4-10). Effects of gravity 
were not included in the simulations, although gravity could have important effects, depending 
on the geometrical relation between the intrusion and the host rock. Both equivalent and 
dual-continuum models were considered. 
11.4.7.1 The Computer Code FLOTRAN 
To estimate the thermal evolution of host rocks surrounding an intrusion emplaced above the 
water table, it is essential to take into account the two-phase behavior of the system. Latent heat 
of solidification of the intrusion is neglected, because this process is relatively fast compared to 
the time required for the intrusion to reach ambient conditions. Preliminary calculations were 
performed using the computer code FLOTRAN (Lichtner 2001 [156429]). FEHM (Zyvoloski et 
al. 1997 [100615]) is limited to temperatures less than approximately 300C and could not be 
used. Both FEHM and FLOTRAN are capable of describing two-phase nonisothermal fluid flow 
in variably saturated media for dual and single continua. A documentation of the mass- and 
heat-conservation equations in the dual-continuum model used in FLOTRAN, and their relation 

to the equivalent-continuum formulation, is presented in Simmons (2002 [157578], SN-LBNLSCI-
108-V2, pp. 1721). 
Equation-of-state properties used in FLOTRAN for pure water were derived from the IFC 
(International Formulation Committee) (1967 [156448]). Constitutive relations must be 
provided as functions of pressure and/or temperature for the density, viscosity, saturated vapor 
pressure curve, internal energy, and enthalpy of pure water. The reported validity of the equation 
of state properties lies in the range of pressure p and temperature T: 0 < p < 165.4  105 Pa 
(165.4 Bars), and 0 < T < 800C (IFC 1967 [156448], p. 1, Figure 2). Although this is satisfied 
for pressure, it is not satisfied for the temperature range needed to describe the intrusion. 
However, as demonstrated in Table 11.4-4, the calculated properties are quite close to the 
measured values reported by Haar et al. (1984 [105175], Table 3) at the maximum temperature 
of interest. 
In the scoping calculations that follow, a one-dimensional (1-D) model was considered of a 
semi-infinite medium representing the host rock in contact with the intrusion (Figure 11.4-10). 
This approach is a simplified model in which the effects of gravity and surface infiltration are 
neglected. By symmetry, only half of the dike width need be modeled. A 30 m (100 ft) wide 
completely dry intrusion with an initial temperature of 1,200C is assumed to be emplaced 
instantaneously into unsaturated tuff at ambient temperature and pressure. 
Rock properties and initial and boundary conditions used in the calculations for the equivalent 
continuum model are listed in Table 11.4-5. The values used for density, specific heat, and 
thermal conductivity for basalt are typical for basalts as listed in Drury (1987 [156447], p. 107). 
Very small values for porosity and permeability of basalt were chosen to simulate an essentially 
impermeable intrusion. The tuff values are representative of the nonwelded Paintbrush tuff 
(PTn) at Yucca Mountain (approximately analogous to the nonwelded tuffs at Paiute Ridge). (It 
should be noted that the host rock at Papoose Lake Sill is now believed to be composed of 
Rainier Mesa tuff, which had not been established at the time these calculations were 
performed.) Values for van Genuchten parameters (fracture/matrix equivalent continuum) are 
means for PTn values in Wu et al. (1997 [156453], Table A-1). Thermal properties of tuff are 
from Francis (1997 [127326], Table B-1). Values for density and porosity are from Peters et al. 
(1984 [121957], Table A-2). Saturation values ranging from 0.4 to 0.6 are observed for the PTn 
at Yucca Mountain, and corresponding calibrated model values were taken from Robinson et al. 
(1997 [100416], Table 5.2). Because of the extreme dryout conditions produced by the high 
temperature of the intrusion, the results are sensitive to the cutoff used to evaluate the 
characteristic curves near the residual saturation. 
11.4.7.2 Dual-Continuum-Model Calculations 
Several cases are considered with varying coupling strength between fracture and matrix 
continua. Values for the fracture-matrix area factor of sfm = 10-6, 10-4, 10-2, and 102 are 
compared and contrasted. Results are shown in Figures 11.4-11 to 11.4-18 for fracture and 
matrix temperature and saturation as functions of distance for various times indicated in the 
figures. Boiling and condensation fronts propagate into the country rock as indicated by the 
100C isotherm and changes in saturation. Liquid water is stable only for temperatures below 
the boiling point, corresponding to approximately 100C at atmospheric pressure. In the figures, 

boiling occurs at the leading edge where saturation increases from zero. The boiling front is 
followed by condensation further away from the intrusion, where both saturation and 
temperature return to ambient conditions. In the intervening region, the temperature is buffered 
at the boiling temperature of 100C. In this region, a heat pipe is present with counterflow of 
liquid and gas. High flow rates of liquid towards the contact are a consequence of capillary 
suction, as the country rock is dried out from heat released from the intrusion. At early times, 
liquid flow rates are on the order of 1,000 m/yr, with gas flow rates several orders of magnitude 
higher. 
As can be seen from the figures, fracture and matrix saturations are very different, even for 
strong coupling between fractures and matrix, in order to preserve equality of the capillary 
pressure between the two continua. For sfm = 100 (shown in Figures 11.4-11 and 11.4-12), the 
dual-continuum results agree with the equivalent-continuum model. Fracture and matrix 
temperatures are identical, and saturations obey Equations II-19 and II-26 in Lichtner (2001 
[156429]). With the fracture volume fraction ef = 0.01, fracture porosity ff 
= 1, and matrix 
porosity fm = 0.47, it follows that the equivalent continuum porosity fe 
. fm and the equivalent 
continuum saturation se . sm, the matrix saturation. The fracture saturation follows from 
Equation II-26 (Lichtner 2001 [156429]). As can be seen from the figures, fracture and matrix 
temperatures become significantly different from one another only in the extreme case of very 
weak coupling strength with sfm = 10-6. For weaker coupling, the fracture network cools 
sufficiently to sustain liquid water at the intrusion-host rock interface for times up to one year, as 
shown in Figure 11.4-19. As heat is conducted from the matrix to the fracture, the water 
vaporizes and the fracture network remains dry until the rewetting phase begins. The matrix 
remains completely dry until rewetting commences. 
The effect of fracture-matrix coupling on fracture saturation is shown in Figure 11.4-19, where 
the fracture saturation at the interface between the basalt intrusion and the tuff host rock is 
plotted as a function of time. Temporary rewetting of the fracture occurs near the basalt-host 
rock contact for times up to one year as the intrusion cools. During this time, the matrix remains 
completely dry and at elevated temperatures well above boiling conditions. The transient 
rewetting of the fracture, however, does not extend very deep into the intrusion. The fracture 
becomes dry as more heat is transferred from the matrix. As the intrusion cools, final rewetting 
requires longer times, ranging from several hundred to over 1,000 years as the coupling strength 
decreases. 
Finally, the role of chemical reactions was investigated briefly by considering the redistribution 
of silica as the intrusion cools and heats up the surrounding host rock. The incorporation of 
chemical processes is complicated by the initial high temperature of the intrusion (~1,200C). 
This condition leads to phase changes as moisture is redistributed throughout the host rock 
(initially two-phase) and the intrusion (initially single-phase gas). In the computer code 
FLOTRAN, all chemical reactions are expressed in terms of a set of primary species that must be 
chosen from the set of aqueous species linked by homogeneous reactions in local chemical 
equilibrium. Thus, an aqueous phase must be present at all times to treat chemical processes. 
Fortunately, it is not necessary to obtain thermodynamic constants at these high temperatures 
because liquid water is never present, on account of the low pressures involved (on the order of 
one bar). 

To accommodate conditions of phase changes from two-phase to single-phase gas and vice 
versa, the approach used in FLOTRAN is to freeze the solution composition at some saturation 
cutoff value, specified by the user, as the system becomes a single-phase gas. For the reverse 
process, involving the transition from single-phase gas to two-phase, this frozen composition is 
released back to solution. Solid that precipitates from solution at a boiling front remains as is 
until that part of the system cools sufficiently for liquid water to once again become stable, after 
which the solid is allowed to react. It is necessary to make certain that the results obtained are 
not sensitive to the value of the saturation cutoff used. 
For the simplified scoping calculation presented here, the matrix of both the host rock and the 
intrusion is considered to be composed of pure amorphous silica representing glass, and the 
fracture continuum is considered to be completely devoid of solid. As the glass matrix dissolves, 
reprecipitation of amorphous silica takes place in the fracture continuum. It should be noted that 
a more detailed description of the chemical system is required to distinguish between the 
different chemical compositions of the basaltic intrusion and the tuff host rock; however, this 
level of detail was not attempted in this preliminary study. Fast kinetics were assumed with 
reaction rates close to local equilibrium. The value for the saturation cutoff used in the 
calculation was 0.001. Figure 11.4-20 shows the volume fraction of amorphous silica in the 
fracture at different times for the case of sfm = 10-2. As the boiling front propagates into the host 
rock, silica precipitates from solution in the fractures. The source of silica is derived from the 
matrix upstream where dissolution of amorphous silica occurs (not shown). This result appears 
to be consistent with field observations at the Papoose Lake Sill. 
11.4.7.3 Discussion 
Although the field observations for mineral alteration are not inconsistent with the 
dual-continuum model predictions, there still remain a number of puzzling features. First, the 
close confinement of the alteration of the tuff host rock to zones adjacent to the intrusion is 
difficult to understand. This is the region that would be expected to be dry over the long term 
until the system cooled and rewetting took place. Whether the alteration could have occurred 
during the relatively rapid and transient passage of the boiling front as it swept through the host 
rock is still unresolved. It would appear difficult, however, to explain the extent of alteration of 
the matrix as caused by such a short-duration, transient event. Unfortunately, alteration of the 
matrix is not properly described by the dual-continuum connected-matrix model used here. A 
better approach would appear to be the dual-continuum disconnected-matrix formulation, which 
was beyond the scope of the present study. 
A second puzzling feature is the sporadic appearance of alteration along the contact rather than a 
more uniform appearance, as modeling would predict. This feature could have several 
explanations. One is that nucleation kinetics were involved, and in most places, the reactions 
simply did not take place, although they were thermodynamically favored. This could be a result 
of low permeability and porosity values present in portions of the tuff (especially those that were 
fused) which would thus restrict the amount of water that could interact with the rock. Another 
possibility is that dehydration reactions of the basaltic dike released volatiles that reacted with 
the tuff host rock. Additionally, the host tuff may have had variable physical and chemical 
properties prior to the intrusion of the sill that might have resulted in non-uniform alteration. 

Sensitivity analyses would help improve future models of the Paiute Ridge system. A number of 
the model input parameters are uncertain, and a sensitivity analysis would be useful to determine 
which parameters have the most impact on model results. In this regard, it should be emphasized 
that, for example, the van Genuchten parameters used for the intrusion and tuff country rock 
were not based on field measurement but were generic values that are approximate at best. The 
initial saturation condition of the tuff host rock plays an important role in moisture and heat 
redistribution, but is difficult, if not impossible, to know saturation values at the time the 
intrusion was emplaced. 
11.4.8 Conclusions of Paiute Ridge Study 
Magmatic intrusions in tuffaceous rock above the water table offer a unique opportunity to study 
conditions analogous to the potential Yucca Mountain high-level nuclear waste repository 
following emplacement of waste. The Paiute Ridge intrusive complex in partially saturated tuff 
appears to offer a possible natural analogue site. A new result of this study is that the Papoose 
Lake Sill apparently intruded into Rainier Mesa tuff, and the resulting hydrothermal process was 
characterized by low-temperature alteration of glass to clinoptilolite and opal. The key 
observations of this study suggest that: 
The intrusion generally occurred at shallow levels and decreased in depth away from the 
central intrusive complex. 
The basalt along the contact is sheeted into narrow vertically or horizontally jointed 
plates, depending on whether the host tuff is exposed adjacent to or beneath the sill. 
Variable cooling patterns (e.g., glassy or crystallized fused tuff) occurred as noted along 
the intrusive contact. 
Alteration of nonwelded tuff to clinoptilolite and opal is similar to that observed in 
diagenetic processes at Yucca Mountain. 
Fractured zones in the tuff created by the basaltic intrusion were sealed by extensive 
silica remobilization during hydrothermal processes, resulting in low-porosity, highly 
indurated tuffs adjacent to the intrusive body. 
Hydrothermal alteration was confined to a narrow zone close to the contact zone, as 
indicated by major and trace element chemical data. 
Field observations at the Paiute Ridge intrusive complex and results from laboratory analysis of 
altered and unaltered tuffs illustrate the intensity of hydrothermal alteration and extent of THC 
processes associated with thermal perturbation of rhyolitic ash flow tuffs. The secondary 
mineral assemblages are similar to those present at Yucca Mountain, and the presence of these 
minerals in the tuff at Paiute Ridge indicates the extent of the alteration. The pervasive 
anastomosing opal veins and associated secondary minerals (e.g., clinoptilolite, calcite, 
cristobalite) appear to have reduced matrix or fracture permeability in the immediate vicinity of 
the basaltic intrusion. The observed mineral zonations can be used to evaluate coupled process 
models. The widespread opal veins along fracture-matrix margins provide a means for 

evaluating porosity/permeability relationships and descriptions of fracture-matrix interaction 
employed in THC codes. 
Preliminary results were presented for a one-dimensional THC dual-continuum model of the 
interaction of country rock with heat released from an intrusive complex emplaced above the 
water table. A simplified chemical system was considered involving precipitation and 
dissolution of amorphous silica. Results demonstrated the possibility of forming opal-filled 
veins with the source of silica derived from the matrix of the host rock. However, because of the 
irregularities caused by kinetic barrier effects associated with reaction of glass, it is important to 
compare and contrast a number of different natural analogue sites to be able to derive general 
conclusions regarding mineral alteration and, specifically, the effect of heat generated by a 
potential repository in tuff at Yucca Mountain. 
Finally, an unexplained observation of this study is the proximal confinement of alteration of the 
tuff host rock to the intrusion. Additional modeling studies, and analytical data such as isotopes, 
would elucidate the mechanisms responsible for the observed alteration patterns. A more 
extensive treatment of chemical processes, combined with the dual-continuum disconnected 
matrix formulation of the dual-continuum model, would allow for discretization of the rock 
matrix, thus resulting in more representative simulation results. 
11.5 ANALOGUES TO THC EFFECTS ON TRANSPORT 
The Marysvale hydrothermal uranium-molybdenum ore deposit in Utah has been evaluated as a 
natural analogue for evaluating the effects of water-rock interaction and radionuclide transport. 
Depletions in igneous rock d18O values were interpreted to result from exchange with circulating 
meteoric waters (Shea and Foland 1986 [156672], p. 281). The largest 18O depletions were 
observed along an intrusive contact, where enhanced fluid flow was thought to have occurred. 
Uranium mineralization related to the hydrothermal event associated with the intrusion appears 
to be concentrated along faults and fractures (Shea 1984 [156673], p. 327). Uranium is primarily 
concentrated in uranium-bearing mineral phases, such as uraninite and coffinite, but is also found 
associated with sericite and chlorite along zones of microfracturing. The observed distribution of 
uranium was interpreted to be due to both bulk-flow and diffusion-transport processes, with most 
transport (and subsequent deposition) occurring within the fracture network. 
Wollenberg et al. (1995 [157467]) used gamma-ray spectrometry and fission-track radiography 
to examine the location and abundance of uranium and thorium in tuffaceous rocks 
encompassing hydrothermal systems at the Long Valley caldera, California, and the Valles 
caldera, New Mexico. In the lateral flowing hydrothermal system at the Long Valley caldera, 
where temperatures range from 140200oC, uranium is concentrated to 50 ppm with Fe-rich 
mineral phases in brecciated tuff fragments. In the vapor zone of the Valles calderas 
hydrothermal system (temperature ~100oC), the concordance of high uranium, low Th/U, and 
decreasing whole-rock oxygen-isotope ratios suggests that uranium was concentrated in response 
to hydrothermal circulation when the system was formerly liquid-dominated. In the underlying 
present-day liquid-dominated zone (temperature to 210oC), up to several tens of parts per million 
uranium occurs with pyrite and Fe-oxide minerals, and in concentrations to several percent with 
a Ti-Nb-Y rare-earth mineral. 

In the Valles calderas outflow zone, uranium is also concentrated in Fe-rich zones, as well as in 
carbonaceous-rich zones in the Paleozoic bedrock that underlies the Quaternary tuff. Thorium, 
associated with accessory minerals, predominates in breccia zones and in a mineralized fault 
zone near the base of the Paleozoic sedimentary sequence. Relatively high concentrations of 
uranium occur in springs representative of water recharging the Valles calderas hydrothermal 
system. By contrast, considerably lower uranium concentrations occur in hot waters (>220oC) 
and in the systems outflow plume, suggesting that uranium is being concentrated in the hotter 
part of the system. The Long Valley and Valles observations indicate that uranium and radium 
are locally mobile under hydrothermal conditions, and that the reducing conditions associated 
with Fe-rich minerals and carbonaceous material are important factors in the adsorption of 
uranium and its attenuation in water at elevated temperature. The Valles and Long Valley 
studies provide evidence for at least localized mobility of uranium and its daughters in tuff and 
underlying sedimentary rocks at temperatures comparable to those expected in a nuclear waste 
repository environment. 
11.6 ANALOGUES TO THM EFFECTS 
11.6.1 Insights from Field Tests 
Results of heater tests conducted at the NTS in granite and tuff and at the Stripa Swedish 
underground laboratory in granite showed a decrease in fracture permeability as a result of 
thermal expansion. The Climax spent fuel test at the NTS was conducted in a 426 m deep shaft 
in granite. During the three-year test, temperatures in the monitored region of the rock mass 
reached 80oC (Hardin and Chesnut 1998 [150043], pp. 4-1 to 4-3). No significant changes in 
mineralogy or microfracturing occurred as a result of heat or irradiation. Monitored permanent 
displacements were on the order of 0.11 mm (Hardin and Chesnut 1998 [150043], p. 4-3). The 
sense of displacement was consistent with the regional extensional tectonic regime. 
Four heater experiments were conducted in G-tunnel, within Rainier Mesa, NTS. In the heatedblock 
test, rock-mass mechanical and thermomechanical properties were measured in tuff under 
controlled thermal and stress-loading conditions. The block was subjected to maximum 
temperatures ranging from 76145oC, and equal biaxial stresses with magnitudes up to 10.6 MPa 
(Zimmerman et al. 1986 [138273], pp. viiix). The permeability of a single, near-vertical 
fracture was measured. The largest changes in permeability were associated with excavation of 
the block, when the apparent permeability increased from 76 to 758 microdarcies. Subsequent 
compressive loading decreased the permeability but did not completely reverse the unloading 
conditions, and the apparent permeability ranged from 252332 microdarcies over a stress range 
of 3.110.6 MPa (Hardin and Chesnut 1998 [150043], p. 4-6). Increased temperature under 
biaxial confinement decreased the fracture aperture, lowering the apparent permeability from 234 
to 89 microdarcies during heating. 
In addition to full-scale heater tests that investigated short-term near-field effects from thermal 
loading, a time-scaled heater test was also performed at the Stripa underground laboratory to 
investigate the long-term thermomechanical response to thermal loading (Robinson 1985 
[157445]). In the full-scale and time-scale heater tests, heat flow was not affected by fractures or 
other discontinuities in the granitic rock mass. Thermoelastic deformation of the rock mass was 
nonlinear and less than predicted. Fracture closure in response to thermal expansion was 

confirmed by observation of diminished water inflow to the heater and instrument boreholes 
(Nelson et al. 1981 [150092], pp. 7880) and by increased compressional wave velocity during 
heating (King and Paulsson 1981 [157444], p. 699). 
11.6.2 THM Insights from Geothermal Fields 
During the 1970s and 1980s, The Geysers geothermal region was rapidly developed as a site of 
geothermal power production. The likelihood that this could cause significant strain within the 
reservoir, with corresponding surface displacements, led to a series of deformation monitoring 
surveys from 1973 to 1996. For the period 1980-1994, peak volume strains occurred in excess of 
5  104. Changes in reservoir steam pressures were well correlated with volume strain and 
contraction of the reservoir (Mossop and Segall 1999 [157466], p. 29,113). 
Seismicity has been induced by oil and gas production in areas where pore pressures have 
decreased, in some cases by several tens of MPa (Segall and Fitzgerald 1998 [157464], p. 117). 
Induced earthquakes are also common in geothermal fields, such as The Geysers, where strong 
correlations between earthquake activity and both steam production and condensate injection, 
have been observed. Stress measurements within hydrocarbon reservoirs show that the least 
horizontal stress decreases with declining reservoir pressure, as predicted by poroelasticity. 
Production-induced stressing may promote frictional sliding on pre-existing faults. However, it 
is not expected that this magnitude of stress will occur at Yucca Mountain. 
Studies of hydraulic fracturing experiments in hot dry rock suggest that under thermal 
conditions, mechanical stresses in the rock at Yucca Mountain will occur along preexisting 
fracture zones and will develop in the direction of maximum principal stress. The Hijori hot dry 
rock site in Yamagata, Japan, was the site of hydraulic fracturing experiments in 1988 that were 
accompanied by microseismic events (Sasaki 1998 [157465], p. 171). The microseismic events 
were thought to have been caused by shear failures induced by high pore-fluid pressures 
occurring on planes of weakness in the rock surrounding the main hydraulic fracture. The 
experiment indicated a migration of the induced microseismic events that eventually distributed 
along a vertical plane, with the strike of seismicity nearly parallel to the direction of the 
maximum principal stress. The vertical orientation and east-west strike of the seismic events are 
essentially coplanar with the caldera ring-fault structure in the southern portion of the Hijiori 
Caldera. This indicates that a preexisting fracture zone was being reopened and developed in the 
direction of maximum principal stress. 
11.7 SUMMARY AND CONCLUSIONS 
Geothermal systems illustrate a variety of THC processes that are relevant to Yucca Mountain. 
They include advective and conductive heating, fracture-dominated fluid flow, chemical 
transport, boiling and dryout, condensation, and mineral alteration, dissolution, and precipitation. 
Yellowstone and other geothermal systems in welded ash flow tuffs or other low-permeability 
rocks indicate that fluid flow is controlled by interconnected fractures. Alteration in lowpermeability 
rocks is typically focused along fracture-flow pathways. Only a small portion of 
the fracture volume needs to be sealed in order to retard fluid flow effectively. At Yucca 
Mountain, fluid flow and low-temperature water-rock interaction over the past 10 m.y. have 

resulted in the precipitation of minor amounts of opal and calcite on fracture and lithophysal 
cavity surfaces. 
The main minerals predicted to precipitate in the near field of the Yucca Mountain repository are 
amorphous silica and calcite, which are also commonly found as sealing minerals in geothermal 
systems. 
Sealing in geothermal fields can occur over a relatively short time frame (days to years). 
Precipitation of minerals can be triggered by a variety of processes, including boiling, water-rock 
interaction, heating and cooling of fluids, and fluid mixing. The unsaturated conditions, lower 
temperatures, and much lower fluid-flow rates predicted for the Yucca Mountain system in 
comparison to geothermal systems, should result in less extensive water-rock interaction than is 
observed in geothermal systems. 
Fracturing and sealing occur episodically in geothermal systems. Different generations of 
fracture mineralization indicate that there are multiple pulses of fluid flow, recording distinct 
temperature conditions and fluid compositions, throughout the lifespan of a geothermal system. 
Most mineralization at Yucca Mountain is predicted to occur soon after waste emplacement 
(1,0002,000 yr), when temperatures would reach boiling (for the higher-temperature operating 
mode) above the emplacement drifts. 
The effects of processes such as boiling, condensation, dissolution, and precipitation on the 
higher-temperature operating mode for Yucca Mountain will be restricted to the near-field 
environment. Silica precipitation at Yellowstone results from both cooling and boiling 
processes, which serve to raise silica concentrations to above saturation levels. Geochemical 
modeling of fluid compositions has been used to successfully predict observed alteration of 
mineral assemblages at Yellowstone. 
As shown in Section 11.3, THC processes are expected to have a much smaller effect on 
hydrogeological properties at Yucca Mountain than on those observed at Yellowstone. 
However, development of a heat pipe above emplacement drifts at Yucca Mountain under a 
higher-temperature operating mode could lead to increased chemical reaction and transport in the 
near field. Reflux and boiling of silica-bearing fluids within the near field at Yucca Mountain 
could cause fracture plugging, thus changing fluid-flow paths. THC simulations conducted to 
date for the potential Yucca Mountain repository suggest that only small reductions in fracture 
porosity (13%) and permeability (<1 order of magnitude) will occur in the near field as a result 
of amorphous silica and calcite precipitation (BSC 2001 [155950], Section 4.3.6.4.2). Changes 
in permeability, porosity, and sorptive capacity are expected to be relatively minor at the 
mountain scale, where thermal perturbations will be minimal; this also applies to the lowertemperature 
(sub-boiling) design. These predicted changes in hydrogeological properties should 
not significantly affect repository performance. 
Magmatic intrusions in tuffaceous rock above the water table, such as the Paiute Ridge intrusive 
complex studied in Section 11.4, offer a unique opportunity to study conditions analogous to the 
predicted postclosure repository conditions at Yucca Mountain. The Papoose Lake Sill intruded 
into Rainier Mesa tuff, and the resulting hydrothermal effects were characterized by lowtemperature 
alteration of glass to clinoptilolite and opal, similar to those currently present at 

Yucca Mountain. Hydrothermal alteration was confined to a narrow zone close to the contact 
zone. The pervasive anastomosing opal veins and associated secondary minerals (e.g., 
clinoptilolite, calcite, cristobalite, etc.) appear to have reduced matrix or fracture permeability in 
the immediate vicinity of the basaltic intrusion. 
The widespread opal veins along fracture-matrix margins provide a means for testing and 
validating porosity/permeability relationships and descriptions of fracture-matrix interaction 
employed in THC codes. Preliminary results of a one-dimensional THC dual-continuum model 
of the interaction of country rock with heat released from an intrusive complex emplaced above 
the water table demonstrate the possibility of forming opal-filled veins with the source of silica 
derived from the matrix of the host rock. However, because of the irregularities caused by 
kinetic barrier effects associated with the reaction of glass, it is important to compare and 
contrast a number of different sites to be able to derive general conclusions regarding mineral 
alteration and, specifically, the effect of heat generated by a potential repository in tuff at Yucca 
Mountain. 
Examples provided in Section 11.5 indicate that the observed distribution of uranium resulting 
from hydrothermal conditions at Marysvale was a result of advective transport and diffusion, 
with most transport-subsequent precipitation of uranium occurring within the fracture network. 
This observation was also borne out at portions of the Long Valley and Valles calderas. The 
latter two studies also provided evidence for at least localized mobility of uranium-series 
radioisotopes at temperatures more comparable to those expected under higher-temperature 
thermal-loading conditions in a nuclear waste repository environment. 
THM effects at Yucca Mountain (Section 11.6) are expected to be less extreme than those 
operating in geothermal fields where microseismicity is detected. 

Table 11.2-1. THC Processes in Geothermal Systems and Their Applicability to Yucca Mountain 
THC Process 
Geothermal System 
Component 
Geothermal 
Examples 
Applicability to 
Yucca Mountain 
Potential Impact to 
Repository 
Performance 
Advective 
heating 
Heat transfer within 
convecting geothermal 
reservoir: develop 
near-isothermal 
vertical thermal profiles 
Nearly ubiquitous: 
examples include 
Yellowstone 
(Wyoming), Salton Sea 
(California), Wairakei 
(New Zealand) 
Would only occur very 
locally in hightemperature 
(>100C) 
design (within heat 
pipe) 
Could result in 
localized zone of 
enhanced water-rock 
interaction and 
chemical transport 
Conductive 
heating 
Heat transfer within 
low-permeability and 
unsaturated portions of 
geothermal systems 
Nearly ubiquitous: 
examples include hot 
dry rock resources, 
upper portions of San 
Vicente (El Salvador), 
Amatitlan (Guatemala) 
Main mechanism of 
heat transfer at Yucca 
Mountain (unsaturated 
conditions) 
Heating leads to more 
rapid chemical 
reactions. Thermal 
expansion of rocks 
could alter fracture 
permeability 
Fracturedominated 
fluid 
flow 
Fluid flow in fractured 
reservoir rocks with 
low matrix permeability 
Silangkitang 
(Indonesia), Dixie 
Valley (Nevada), Los 
Azufres (Mexico) 
Main mechanism for 
fluid flow within welded 
ash flow tuffs at Yucca 
Mountain 
Could permit rapid 
movement of fluids 
along fast flow paths 
(evidenced by bombpulse 
tritium) 
Chemical 
transport 
Advective and diffusive 
transport of dissolved 
constituents in fluids. 
Tracer tests used to 
determine fluid flow 
paths and rates. 
Ubiquitous. Welldocumented 
tracer 
tests for many 
geothermal systems, 
including The Geysers 
(California), Dixie 
Valley (Nevada), Coso 
(California), 
Awibengkok 
(Indonesia) 
Advective transport 
within fractures, and 
advective and diffusive 
transport between 
fractures and matrix 
Potential mechanism 
for movement of 
radioactive waste 
materials from 
repository 
Boiling 
Development of twophase 
and steam 
zones in geothermal 
systems due to 
depressurization and 
heating 
Occurs in most hightemperature 
liquiddominated 
geothermal 
systems with 
production, e.g., 
Awibengkok 
(Indonesia), Coso 
(California), and 
occurs naturally in 
steam-dominated 
systems, e.g., The 
Geysers (California), 
Karaha-Telaga-Bodas 
(Indonesia). 
Would only occur in 
high-temperature 
design near drift walls 
for limited time 
Would create dryout 
zone around drift for 
high-temperature 
design, and could lead 
to development of heat 
pipe. Fracture 
permeability could be 
modified by 
precipitation caused by 
boiling. 
Dryout 
Occurs during 
transformation from 
liquid-dominated to 
steam-dominated 
geothermal system 
Documented for The 
Geysers (California), 
Karaha-Telaga-Bodas 
(Indonesia) 
Would only occur in 
high-temperature 
operating mode near 
drift walls for limited 
time 
Dryout zone would 
prohibit seepage into 
drift for early stages of 
high-temperature 
operating mode. Would 
lead to precipitation of 
dissolved solids in area 
that could be 
redissolved as cooling 
and rewetting 
occurred. 

Table 11.2-1 (Continued). THC Processes in Geothermal Systems and Their Applicability to Yucca 
Mountain 
THC Process 
Geothermal System 
Component 
Geothermal 
Examples 
Applicability to 
Yucca Mountain 
Potential Impact to 
Repository 
Performance 
Condensation 
Occurs during 
transformation from 
liquid-dominated to 
steam-dominated 
geothermal system, 
and in upper levels of 
geothermal systems 
where rising vapor 
contacts cooler 
meteoric waters 
Observed in many 
geothermal systems 
where rising gas and 
steam is cooled and 
mixes with nearsurface 
meteoric fluids, 
resulting in 
development of 
bicarbonate and acidsulfate 
springs. 
Documented for 
Yellowstone 
(Wyoming), Wairakei 
(New Zealand), 
Waiotapu (New 
Zealand) 
Would mainly occur in 
high-temperature 
design above drift 
areas for limited time; 
can also occur in lowtemperature 
design, 
but at a reduced level 
Condensation above 
drift could lead to 
recycling of fluids, thus 
resulting in a higher 
volume of fluids 
passing through nearfield 
area. This could 
also result in localized 
zones of nearsaturation 
conditions 
and increase waterrock 
interaction. 
Condensation could 
also take place in the 
drift, resulting in 
dripping on waste 
packages. 
Mineral 
dissolution 
Occurs typically in 
condensation zones, or 
where acid fluids are 
present 
Difficult to document, 
but observed at The 
Geysers (California) 
and Karaha-Telaga- 
Bodas (Indonesia) 
Would occur primarily 
where condensation 
occurs 
Mineral dissolution 
associated with 
condensation zone 
could lead to local 
increases in porosity 
and permeability. 
Mineral 
alteration and 
precipitation 
Occurs in numerous 
portions of geothermal 
systems, especially in 
zones with abundant 
fluid flow that have 
undergone heating 
Ubiquitous. Degree 
and type of 
mineralization depends 
on rock and fluid 
compositions, waterrock 
ratios, and 
temperature. Boiling 
can result in significant 
mineralization. 
Alteration mineralogy 
well-characterized at 
Wairakei (New 
Zealand), Salton Sea 
(California), 
Silangkitang 
(Indonesia), Krafla 
(Iceland) 
Alteration and 
precipitation likely to 
be confined to nearfield 
environment, 
where boiling and 
increased fluid flux 
occur. These effects 
may be negligible for 
low-temperature 
design. 
Alteration could lead to 
changed sorption 
properties (zeolite and 
clay formation). 
Precipitation of silica 
minerals and calcite in 
fractures could locally 
reduce permeability, or 
lead to focussed flow 
within a few larger 
fractures. 
Source: Simmons 2002 [157578], SN-LBNL-SCI-108-V2, pp. 1415. 

Table 11.2-2. Estimated Process Time Scales for YM Repository and Geothermal Reservoirs 
Process 
Repository 
Time Scale (yr) 
Geothermal Reservoir 
Time Scale (yr) 
Duration of heating (magma or nuclear 
waste) 
1000s 
10,000s 
Dryout 
100s to 2,000 
10,000s 
Fast-path flow from ground surface to 
repository or geothermal system 
10s 
10s 
Water recycling in "heat pipe" (cyclic 
liquid-vapor counterflow) 
<<1 
1s to 10s 
Intermittent flow events 
<<<1 
<<<1 
Physical changes due to dissolution and 
precipitation 
<1 to 1,000s 
<1 to 10,000s 
Mineralogic changes 
<1 to 1,000s 
<1 to 10,000s 
Climate change 
10,000s 
10,000s 
Source: Simmons 2002 [157578], SN-LBNL-SCI-108-V2, p. 15. 
Table 11.3-1. Comparison of Yellowstone and Yucca Mountain Systems 
Yucca Mountain 
Repository 
Yellowstone Geothermal System 
Boiling zone temperatures 
~95C 
92270C 
SiO2 in fluids 
<200 ppm 
200700 ppm 
Duration of boiling conditions 
<1,200 yr (high T) 
0 years (low T) 
=15,000 yr 
Fluid-flow conditions 
Unsaturated 
Saturated 
Estimated fluid flux 
10-9 to 10-10 m/s 
4.8  10-5 m/s 
Estimated heat flux 
16.7 W/m2 (in near-field area 
around waste packages) 
46 W/m2 (Firehole River Drainage Basin) 
1.7 W/m2 (Yellowstone Caldera) 
Source: Simmons 2002 [157578], SN-LBNL-SCI-108-V2, p. 15. 

Table 11.4-1. Samples, Lithologic Types and Descriptions, and Measured 
and Estimated Distances of Tuff Samples from a Basaltic Intrusion 
Sample Number 
Distance to 
Contact (ft) 
[m] 
Lithology 
Sample Description 
Adjacent and west of Papoose Lake Sill 
PR00-3-15-1 (LANL# 3547) 
Contact 
Basalt 
Purplish gray, fine grained, platy, and altered 
PR00-3-15-2 (LANL# 3548) 
4.5 [1.4] 
Vitrophyre 
Fused tuff, glassy, foliated, and 7 ft (2.1 m) wide 
PR00-3-15-3 (LANL# 3549) 
3.0 [0.9] 
Vitrophyre 
Fused tuff, glassy, foliated, and contains silica 
veinlets 
PR00-3-15-4 (LANL# 3550) 
8.5 [2.6] 
Baked tuff 
Hardened, pinkish orange, and devitrified 
PR00-3-15-5 (LANL# 3551) 
12.5 [3.8] 
Tuff 
Partially welded, cavernous, and pinkish orange 
PR00-3-15-6 (LANL# 3552) 
15.5 [4.7] 
Opal vein 
3 wide, NS trend parallel to contact, and reddish 
PR00-3-15-7 (LANL# 3553) 
15.5 [4.7] 
Tuff 
Within opal vein zone, pinkish, contains few opal 
nodules 
PR00-3-15-8 (LANL# 3554) 
12.5 [3.8] 
Opal vein 
N20E trend, crystalline, variable thickness, cuts 
nonwelded tuff 
PR00-3-15-9 (LANL# 3555) 
29 [8.8] 
Tuff 
Altered, silicified, pinkish and fine grained 
PR00-3-15-10 (LANL# 3556) 
29.4 [9.0] 
Tuff 
Nonwelded, collected within silicified zone, pinkish 
PR00-3-15-11 (LANL# 3557) 
43 [13.1] 
Tuff 
Nonwelded, cut by few opal veins, pinkish 
PR00-3-15-12 (LANL# 3558) 
82 [25] 
Tuff 
Nonwelded, pinkish, pumice-rich 
PR00-3-15-13 (LANL# 3559) 
200 [61] 
Tuff 
Nonwelded, pinkish, friable, pumice-rich, and 
cavernous 
Above and East of Papoose Lake Sill 
PR00-3-14-2 (LANL# 3538) 
~150 [46] 
Tuff 
Pale pink tuff cut by opal veins, dark red halo, 
pumice clasts 
PR00-3-14-3 (LANL# 3539) 
~150 [46] 
Tuff 
Same as LANL# 3538 with thicker veins and 
alteration 
PR00-3-14-4 (LANL# 3540) 
~150 [46] 
Tuff 
Same tuff with pumice clasts and nodule 
PR00-3-14-5 (LANL# 3541) 
~150 [46] 
Tuff 
Same tuff with corroded pumice clasts and devitrified 
PR00-3-14-6 (LANL# 3542) 
~150 [46] 
Opal vein 
1 cm wide in a similar tuff, contains fresh pumice 
clasts 
PR00-3-14-7 (LANL# 3543) 
~150 [46] 
Tuff 
Same tuff with dense pumice 
PR00-3-14-8 (LANL# 3544) 
~150 [46] 
Tuff 
Same tuff with thick opal veins 
PR00-3-14-9 (LANL#3545) 
>150 [46] 
Tuff 
Tuff east of opal vein zone, gray, no veins, pumice 
less distinct 
PR00-3-15-14 (LANL# 3560) 
~400 [122] 
Tuff 
Nonwelded, matrix silicified, few opal veins, reddish 
brown 
PR00-3-15-15 (LANL# 3561) 
~400 [122] 
Tuff 
Nonwelded with nodules, pumice-rich, grayish, 
cavernous 
PR00-3-15-16 (LANL# 3562) 
~500 [152] 
Tuff 
Dark reddish orange, nonwelded, friable, massive 

Table 11.4-1 (Continued). Samples, Lithologic Types and Descriptions, and Measured 
and Estimated Distances of Tuff Samples from a Basaltic Intrusion 
Above and East of Papoose Lake Sill (Continued) 
PR00-3-15-17 (LANL# 3563) 
720 [220], 
60.0 [183] 
west of 
dike 
Tuff 
Moderately welded with opal nodules, grayish 
PR00-3-15-18 (LANL# 3564) 
695 [212], 
38.5 [11.7] 
west of dike 
Tuff 
Moderately welded with opal nodules, orangish 
PR00-3-15-19 (LANL# 3565) 
660 [201], 
3.0 [0.9] 
west of dike 
Fused tuff 
Fused with fiamme and nodules, pinkish brown 
Beneath Sill (Figure 11.4-1, Section B) 
PR00-3-16-1 (LANL# 3570) 
Top part of 
sill 
Basalt 
25 ft (7.6 m) thick, sparsely porphyritic, amygdules 
PR00-3-16-2 (LANL# 3571) 
Contact 
Basalt-tuff 
Platy basalt, fused granular tuff, no vitrophyre 
PR00-3-16-3 (LANL# 3572) 
1 [0.3] 
Tuff 
Pinkish gray, medium grained, partially fused 
PR00-3-16-4 (LANL# 3573) 
4.4 [1.3] 
Tuff 
Nonwelded, bedded, coarse, and crystal-rich 
PR00-3-16-5 (LANL# 3574) 
4.4 [1.3] 
Tuff 
Fine grained, pinkish gray, tilted 20S 
PR00-3-16-6 (LANL# 3575) 
15 [4.6] 
Tuff 
Moderately welded, light gray, contains lithics 
PR00-3-16-7 (LANL# 3576) 
21 [6.4] 
Opal vein 
2 ft (0.6 m) wide, fractured, orange and white veins 
PR00-3-16-8 (LANL# 3577) 
30.8 [9.4] 
Opal vein 
Host tuff fractured, same as LANL# 3576 
PR00-3-16-9 (LANL# 3578) 
34.2 [10.4] 
Tuff 
Nonwelded, light gray, and contains lithics 
PR00-3-16-10 (LANL# 3579) 
35 [10.7] 
Tuff 
Crystal-rich, coarse, pumice-rich, matrix-free 
PR00-3-16-11 (LANL# 3580) 
16 [4.9] 
Opal 
0.4-1.5 ft (0.1 to 0.5 m) thick, N-S trend, dips 65E, 
(98 ft) (30 m) long 
PR00-3-16-12 (LANL#3581) 
8 [2.4] 
Tuff 
Host tuff for the (98 ft) (30 m) long opal vein 
Source: Simmons 2002 [157578], SN-LANL-SCI-215-V1, pp. 1327, 9094. 

Table 11.4-2. Subsurface Stratigraphic Information from Drill Holes along the Eastern Part of Yucca Flats Adjacent to Paiute Ridge 
Drill Holes: Interval Thickness, I (m), and Depth to the Tops of Formations, D (m) 
U 3mk 
U 7at 
U 7bg 
U 7bh 
U 7bk 
U 7bm 
U 7bo 
UE7h 
UE 7m 
U 7x 
Stratigraphic Units 
(upper one third of 
section) 
I 
D 
I 
D 
I 
D 
I 
D 
I 
D 
I 
D 
I 
D 
I 
D 
I 
D 
I 
D 
Qal 
(Qta) 
65.5 
82.3 
48.8 
54.9 
41.1 
92.4 
138.7 
51.8 
61 
67.1 
Tma 
Ammonia Tanks 
none 
None 
none 
none 
29 
48.8 
21.3 
54.9 
none 
none 
none 
none 
none 
none 
18.3 
51.8 
none 
none 
none 
none 
Tmab 
Bedded Ammonia 
Tanks 
none 
None 
none 
none 
70.1 
68.6 
none 
none 
none 
none 
none 
none 
62.5 
none 
none 
none 
none 
Tmr 
Rainier Mesa 
56.4 
65.5 
21.3 
82.3 
67.1 
77.7 
48.8 
76.2 
54.9 
41.4 
95.1 
92.4 
47.2 
138.7 
82.3 
70.1 
94.5 
61 
73.2 
67.1 
Tx 
(Tmrl/T 
a) 
Rainier Mesa/ 
Vitrophyre 
24.4 
121.9 
35.1 
103.6 
32 
144.8 
39.6 
125 
38.1 
96 
59.4 
187.5 
39.6 
185.9 
4.6 
152.4 
39.6 
155.4 
=73.1 
140.2 
Tpc 
Tiva Canyon 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
Tpt 
Topopah Spring 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
Tac 
Calico Hills 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
Tw 
Lower Wahmonie 
24.4 
146.3 
21.3 
138.7 
18.3 
176.8 
19.8 
164.6 
21.3 
134.1 
18.3 
246.9 
15.2 
225.6 
18.3 
157 
21.9 
195.1 
nd 
nd 
Tc 
Crater Flat 
56.4 
170.7 
51.8 
160 
43.3 
195.1 
82.3 
184.4 
44.2 
155.4 
80.8 
265.2 
51.8 
240.8 
59.4 
175.3 
51.2 
217 
nd 
nd 
Tcb 
Bull Frog 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
nd 
Surface elevation 
(m) 
1297.8 
1336.6 
1337.5 
1338.7 
1333.5 
1291.7 
1319.2 
1338.7 
1315.2 
1328.9 
Drill hole depth (m) 
381 
460.4 
396.2 
396.2 
376.4 
472.4 
609.6 
780.6 
587 
533.4 
Depth to pervasive 
zeolitization (m) 
281.9 
182.9 
167.6 
157 
198.1 
243.8 
262.1 
152.4 
240.8 
222.5 
NOTE: nd means not defined. Values in bold-type indicate depth to Rainier Mesa Vitrophyre Unit. 
Source: Drellack and Thompson 1990 [156446], pp. 60, 64, 66, 6869, 118, 122, 124, 126127. 

Table 11.4-3. Quantitative Mineral Abundances by XRD for Selected Tuff Samples 
Adjacent to Papoose Lake Sill in the Northern Part of Paiute Ridge 
Sample 
Smectite 
Clinoptilote 
Chabazite 
Tridymite 
Cristobalite 
Opal- 
CT 
2ndary 
Quartz 
K-Spar 
Plagioclase 
Glass 
Hematite 
Biotite 
Hornblende 
Augite 
Calcite 
Total 
PR00-3-15-01, LANL# 3547 
18.5 
 
 
 
 
 
 
8.1 
52.8 
 
3.0 
2.1 
 
16.5 
 
101.0 
PR00-3-15-02, LANL# 3548 
 
 
0.8 
0.9 
0.4 
 
5.7 
1.0 
8.2 
79.8 
 
0.2 
 
 
 
97.1 
PR00-3-15-03, LANL# 3549 
 
 
1.0 
3.4 
0.9 
 
3.7 
3.5 
13.9 
75.2 
 
0.5 
 
 
 
102.0 
PR00-3-15-04, LANL# 3550 
 
 
 
1.4 
1.9 
 
3.6 
3.2 
11.4 
75.4 
 
0.2 
 
 
 
97.1 
PR00-3-15-05, LANL# 3551 
 
 
 
 
 
 
5.3 
4.7 
7.5 
82.8 
0.3 
1.5 
 
 
 
102.2 
PR00-3-15-06, LANL# 3552 
 
55.9 
 
 
1.0 
27.7 
2.4 
7.0 
5.6 
 
 
0.1 
 
 
 
99.6 
PR00-3-15-07, LANL# 3553 
 
2.8 
 
 
 
 
2.9 
8.3 
8.0 
71.8 
0.2 
2.7 
 
 
4.5 
101.3 
PR00-3-15-08, LANL# 3554 
 
26.5 
 
 
 
18.7 
22.7 
13.5 
16.9 
 
 
0.4 
0.1 
 
 
98.8 
PR00-3-15-09, LANL# 3555 
 
64.6 
 
 
0.9 
23.5 
2.3 
4.6 
8.3 
 
 
0.1 
 
 
 
104.3 
PR00-3-15-10, LANL# 3556 
 
6.8 
4.6 
 
 
 
4.5 
6.4 
6.4 
65.5 
0.1 
0.9 
 
 
2.9 
98.2 
PR00-3-15-11, LANL# 3557 
 
3.8 
 
 
 
 
7.3 
5.1 
8.4 
74.5 
 
1.5 
 
 
1.3 
102.0 
PR00-3-15-12, LANL# 3558 
 
 
 
 
 
 
3.6 
2.9 
6.5 
84.7 
0.1 
0.4 
 
 
 
98.1 
PR00-3-15-13, LANL# 3559 
0.1 
 
 
 
 
 
3.8 
3.9 
7.1 
85.2 
0.2 
1.4 
 
 
 
101.6 
NOTE: Mineral abundances are in weight percent;    means not detected. 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 59. 

Table 11.4-4. Comparison of Equation of State Properties of Pure Water at 1,200C 
p 
(bars) 
Density 
(kg/m3) 
Enthalpy 
(kJ/kg) 
Energy 
(kJ/kg) 
Viscosity 
(Pa s) 
FLOTRAN 
HGK 
FLOTRAN 
HGK 
FLOTRAN 
HGK 
FLOTRAN 
HGK 
1 
0.14709 
0.14708 
5,131.03 
5,150.0 
4,451.18 
4,470.1 
40.66 
40.38 
5 
0.7356 
0.7354 
5,130.4 
5,149.2 
4,450.7 
4,469.4 
40.89 
40.39 
10 
1.4714 
1.4710 
5,129.7 
5,148.2 
4,450.1 
4,468.4 
41.18 
40.42 
NOTES: The comparison is between Haar et al. (1984 [105175]) (the HGK columns) and the equation of state used 
by FLOTRAN based on the International Formulation Committee of the Sixth International Conference on 
Properties of Steam (IFC 1967 [156448]) with the reported range of validity of 0 < p < 165.4  105 Pa (165.4 
Bars) and 0 < T < 800C. 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, pp. 102103. 

Table 11.4-5. Basalt and Tuff Hydrothermal-Model Parameters for Fracture (f) and Matrix (m) 
and Dual-Continuum Parameters Used in the THC Simulations 
Property 
Symbol 
Units 
Mafic Intrusion 
Tuff Host Rock 
Fracture Permeability 
kf 
m2 
2.74  10-9 
2.74  10-9 
Matrix Permeability 
km 
m2 
1.0  10-20 
4.66  10-14 
Fracture Porosity 
ff 
 
1.0 
1.0 
Matrix Porosity 
fm 
 
0.05 
0.47 
Rock Density 
.r 
kg m-3 
2,830 
2,410 
Specific Heat 
Cp 
J kg-1 K-1 
1,010 
1,100 
Thermal Conductivity 
Cwet 
J m-1 s-1 K-1 
1.93 
0.61 
Thermal Conductivity 
Cdry 
J m-1 s-1 K-1 
1.93 
0.61 
Gaseous Diffusivity 
D 
m2 s-1 
2.13  10-5 
2.13  10-5 
Temperature Exponent 
. 
 
1.8 
1.8 
Tortuosity 
t 
 
1.0 
1.0 
Residual Saturation 
sr 
 
0.04 
0.04 
van Genuchten Parameter 
af 
Pa-1 
8.92  10-4 
8.92 x 10-4 
van Genuchten Parameter 
am 
Pa-1 
4.15  10-5 
4.15  10-5 
van Genuchten Parameter 
.f 
 
0.449 
0.449 
van Genuchten Parameter 
.m 
 
0.327 
0.327 
Initial Temperature 
T0 
C 
1,200 
30 
Initial Saturation 
sl
0 
 
0.0 
0.4 
Dual Continuum Parameters 
Fracture Volume Fraction 
ef 
 
0.01 
0.01 
Matrix Block Size 
lm 
m 
0.5 
0.5 
Frature-Matrix Area Factor 
sfm 
 
100 
0.1 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 104. 

NOTE: Similar processes include boiling and condensation, advective liquid flow, mineral 
dissolution and precipitation, mixing, recharge (percolation), and heat conduction. 
A heat pipe is depicted on the right side of the geothermal system, showing 
countercurrent liquid and vapor flow resulting from boiling and condensation. 
Source: Left figure adapted from Bodvarsson and Witherspoon (1989 [156337]), right adapted 
from CRWMS M&O (2000 [151940]). 
Figure 11.2-1. Comparison of Processes in Geothermal (Left) and Anthropogenic (Right) Thermal 
Systems Created by Emplacing Heat-Generating Nuclear Waste in an Unsaturated Fractured Rock Mass 

NOTE: In both (a) and (b), the water table is indicated by a blue downward-pointing 
triangle. 
Source: CRWMS M&O 2000 [151940], Figure 3.2-1. 
Figure 11.2-2. Schematic Diagram (a) and Cross Section (b) of the Yucca Mountain Lithology and 
Topography, Including Surface Features and Major Geologic Strata 

fracture permeability = 
5  10-12  5  10-9 m2 
MATRIX 
PERMEABILITY 
(m2) 
10-15  10-13 
10-15  10-13 
10-17  10-15 
10-18  10-17 
10-17  10-15 
NOTE: While zones of dense welding have intrinsically low matrix permeabilities, these 
zones also have much more abundant fractures, resulting in higher overall 
permeability than nonwelded (and unfractured) tuff. 
Source: Generic profile modified from Winograd (1971 [156254], Figure 5). 
Figure 11.2-3. Typical Variations in Permeability and Porosity in Welded and Unwelded Ash Flow Tuff 

NOTE: Water is introduced into the fault in Alcove 8 and collected in and near Niche 3. 
Source: Modified from BSC 2002 [157606], Figure 2. 
Figure 11.2-4. Schematic Diagram of Flow Test at Yucca Mountain 

NOTE: Flow rates are slightly greater and enthalpy is slightly less than predicted by the 
1986 model from 1988 to 1992. 
Source: Steingrimsson et al. 2000 [156686], p. 2904. 
Figure 11.2-5. Comparison between Predicted and Observed Flow Rates and Enthalpies for Well 6 of 
the Nesjavellir Geothermal Field (Iceland) 
NOTE: Well M-31 experienced near-well boiling with abundant mineral deposition. 
Cleaning well M-31 in 1981 yielded a short-lived increase in production. WHP = 
well head pressure. 
Source: Truesdell et al. 1984 [156350], p. 227. 
Figure 11.2-6. Comparison of Production between Wells M-5 
and M-31 at the Cerro Prieto Geothermal Field 

NOTE: The botryoidal texture of the quartz indicates that it was deposited as chalcedony 
or amorphous silica, and that this deposition occurred at >300oC due to rapid 
decompression. qtz = quartz, qtz(chal) = chalcedony, py = pyrite, act = actinolite, 
and ep = epidote 
Source: Moore et al. 2000 [156319], p. 261. 
Figure 11.2-7. Photomicrograph of Fracture Minerals in the Karaha-Telaga Bodas System, Indonesia 
NOTE: Titanium-rich scale coats anhydrite and fine needles of actinolite. The scale is 
peeling off the top of the crystal. 
Source: Moore et al. 2000 [156319], p. 260. 
Figure 11.2-8. Scanning Electron Microscope Backscattered Image 
of Fracture Minerals in the Karaha-Telaga Bodas System, Indonesia 

NOTE: In A, quartz and calcite are deposited as the result of boiling possibly due to 
depressurization in the system. Initially, the rock is too hot for condensation to 
occur. In B, the top portion of the vein has cooled sufficiently so that 
condensation occurs. Steam from below migrates through the vein until it 
reaches the cooler rock where condensation occurs. Corrosion of quartz and 
calcite occurs near the site of condensation. In C, subsequent lowering of the 
water table (indicated by the arrow) due to venting results in quartz and calcite 
deposition due to condensate boiling. Mineral deposition may also occur as 
condensate reaches the lower, superheated region, and in the liquid-dominated 
portion of the vein. 
Source: Moore et al 2000 [156318], p. 1731. 
Figure 11.2-9. Schematic Illustration Showing the Transition from a Liquid-Dominated 
System to a Vapor-Dominated System, Showing only a Portion of the Vein 

NOTE: The silicified regions are identified in the right column by cross hatching. 
Source: Bird and Elders 1976 [154601], p. 286. 
Figure 11.2-10. Temperature Profile and Lithology of Borehole 
DWR No. 1 at the Dunes Geothermal System, California 

NOTE: The diatomite was altered to porcelanite and chert as a result of a hydrothermal 
system induced by the intrusion of an andesite dike. The thicknesses of the 
porcelanite and chert layers range from 20 cm to 20 m (porcelanite) and 5 cm to 
20 cm (chert). 
Source: Chigira and Nakata 1996 [156349], p. 15. 
Figure 11.2-11. Schematic of Lithology near Borehole A in the Miocene Iwaya Formation, Japan 

0 
20 
40 
60 
80 
100 
120
1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 
Permeability (cm/s) 
diatomite 
pumice tuff 
porcelanite 
chert 
chert 
porcelanite 
chert 
diatomite 
porcelanite 
NOTE: Alteration mineral porcelanite has a similar permeability to the original diatomite, 
but the chert is far less permeable. 
Source: Data from Chigira and Nakata 1996 [156349], p. 11. 
Figure 11.2-12. Permeability Profile of Samples along Borehole A in the Miocene Iwaya Formation, 
Japan 

NOTE: The temperatures indicate the temperature of the injected water. The 
permeability-thickness product (kh) in Well R-1 decreased from 224 darcy-m to 
0.79 darcy-m over 624 days. In Well R-2, the permeability-thickness product 
decreased from 91 darcy-m to 5 darcy-m over 637 days. 
kh = permeability-thickness product 
koh = initial permeability-thickness product 
Source: Itoi et al. 1987 [156346], pp. 543544. 
Figure 11.2-13. Reduction in Permeability in Wells R-1 and R-2 
over the Duration of a Reinjection Experiment 

NOTE: Areas abbreviated as follows: BC = Black Creek, CH = Crater Hills, GC = Grand 
Canyon, HLB = Hart Lake Basin, HSB = Hot Springs Basin, JC = Josephs Coat 
Hot Spring, MH = Mammoth Hot Springs, NB = Norris Geyser Basin, LB = Lower 
Geyser Basin, MB = Midway Geyser Basin, UB = Upper Geyser Basin, SB = 
Shoshone Geyser Basin, MV = Mud Volcano, WT = West Thumb, WS = 
Washburn Hot Springs, YL = Yellowstone Lake. 
Source: Fournier 1989 [156245], Figure 2. 
Figure 11.3-1. Map of Yellowstone National Park, with Outline of 0.6 Ma Caldera Rim 

DTN: LB0201YSANALOG.001 [157569] 
NOTE: Large sinter blocks had been ejected by 1989 explosion. The pool has an 
opalescent color, indicating presence of colloidal silica (photo by R. Fournier, 
USGS). 
Source: Simmons 2002 [157578], SN-LBNL-SCI-185-V1, p. 7-1. 
Figure 11.3-2. Porkchop Geyser (July 1991) 

DTN: LB0201YSANALOG.001 [157569] 
Source: Simmons 2002 [157578], SN-LBNL-SCI-185-V1, p. 7-1. 
Figure 11.3-3. Block from 1989 Porkchop Geyser Eruption, with Gelatinous, Botryoidal Silica Coating 
Outer Margins and Cavities (photo from T.E.C. Keith, USGS) 

200 
210 
220 
230 
240 
250 
260 
270 
280 
1960 
1963 
1966 
1969 
1972 
1975 
1978 
1981 
1984 
1987 
1990 
Year 
NKC temperature (oC) 
400 
450 
500 
550 
600 
650 
700 
750 
800 
SiO2 (ppm) 
NKC (C) 
SiO2 (ppm) 
Initial geysering 
Continual geysering 
Hydrothermal eruption 
NOTE: Change in flow behavior interpreted to be linked to precipitation of amorphous silica, 
resulting in the clogging of flow channels. 
Source: Fournier et al. 1991 [156246], p. 1116. 
Figure 11.3-4. Changes in Calculated Sodium-Potassium-Calcium (NKC) Reservoir 
Temperatures and Silica Concentrations for Waters Sampled from Porkchop Geyser 

DTN: LB0201YSANALOG.001 [157569] 
Source: Dobson et al. 2001 [154547], Figure 2. 
Figure 11.3-5. Simplified Geologic Log of the Y-5 Core 

DTN: LB0201YSANALOG.001 [157569] 
Source: Dobson et al. 2001 [154547], Figure 3. 
Figure 11.3-6. Simplified Geologic Log of the Y-8 Core 

0 
20 
40 
60 
80 
100 
120 
140 
160 
180 
20 60 100 140 180 
Temperature (C) 
Depth (m) 
0 1 2 3 
Wellhead Pressure (barg) 
Y-8 temp 
Y-5 temp 
Y-8 WHP 
Y-5 WHP 
Y-5 
Y-8 
DTN: LB0201YSANALOG.001 [157569] 
NOTE: Vertical bars at left indicate studied core-depth intervals. Temperature and 
pressure data from White et al. 1975 [154530]. 
Source: Dobson et al. 2001 [154547], Figure 1. 
Figure 11.3-7. Downhole Temperature (Solid Lines) and Wellhead Pressure Variations (Dotted Lines) in 
the Y-5 and Y-8 Wells 
15 
25 
35 
45 
55 
65 
75 
85
0 10 20 30 40 50 
Y-5 Porosity (%) 
Depth (m) 
0.001 0.1 10 1000 
Permeability (md) 
Porosity 
Permeability 
Pumice 
cavity 
Altered & 
brecciated
Clastic 
dikes 
W 
W 
W 
NW
NW 
NW
NW 
Pumice 
W
W 
DTN: LB0201YSANALOG.001 [157569] 
NOTE: W= moderately to densely welded tuff, NW = nonwelded to weakly welded tuff. 
The 0.1 md values represent the lower detection limit for minipermeability 
measurements; actual values are lower. 
Source: Dobson et al. 2001 [154547], Figure 4. 
Figure 11.3-8. Porosity and Permeability Variations in the Y-5 core 

40 
45 
50 
55 
60 
65 
70 
75
0 20 40 60 
Y-8 Porosity (%) 
Depth (m) 
0.001 0.1 10 1000 
Permeability (md)
Porosity 
Permeability 
Pumiceous 
tuff 
Perlitic 
rhyolite lava 
Volcaniclastic 
sediments 
Silica 
sealing 
Fracture 
DTN: LB0201YSANALOG.001 [157569] 
Source: Dobson et al. 2001 [154547], Figure 5. 
Figure 11.3-9. Porosity and Permeability Variations in the Y-8 Core 

0 10 20 30 
20 
25 
30 
35 
40 
45 
50 
55 
60 
65 
70 
75 
80 
85 
Depth (m) 
Veins & Fractures / 2.5 m interval 
Breccia 
zone 
Densely welded 
tuff 
NW 
NW 
NW 
W 
W 
DTN: LB0201YSANALOG.001 [157569] 
NOTE: W= moderately to densely welded tuff, NW = nonwelded to weakly welded 
tuff 
Source: Dobson et al. 2001 [154547], Figure 6. 
Figure 11.3-10. Veins and Fractures in the Y-5 Core 

Natural Analogue Synthesis Report 
TDR-NBS-GS-000027 REV 01 11-88 May 2004 
0 10 20 30 
45 
50 
55 
60 
65 
70 
Depth (m) 
Veins & Fractures / 2.5 m interval 
Nonwelded tuff 
Silicified 
sediments 
Volcaniclastic 
sediments 
Perlitic 
rhyolite 
lava 
DTN: LB0201YSANALOG.001 [157569] 
Source: Dobson et al. 2001 [154547], Figure 8. 
Figure 11.3-11. Veins and Fractures in the Y-8 Core 
DTN: LB0201YSANALOG.001 [157569] 
NOTE: Core width is 4.4 cm. Permeability values of welded tuff clast (A) and matrix (B) 
are both below the minipermeameter detection limit (0.1 md). 
Source: Dobson et al. 2001 [154547], Figure 7. 
Figure 11.3-12. Hydrothermal Breccia from the Y-5 Core at 47.7 m (156.5 feet) 

Y-8, 155.9 
Permeability = 1030 md 
Porosity = 29.2% 
Y-8, 159.2 
Permeability = 16.9 md 
Porosity = 15.0% 
1 mm 1 mm 
DTN: LB0201YSANALOG.001 [157569] 
NOTE: Silicification of the sample from 159.2 has resulted in a 50% reduction in porosity 
(change in abundance of blue epoxy denoting porosity) and decrease in 
permeability of nearly two orders of magnitude. 
Source: Simmons 2002 [157578], SN-LBNL-SCI-185-V1, Roll 17, Photos 2 and 4. 
Figure 11.3-13. Photomicrographs of Volcaniclastic Sandstone Unit from Y-8 Core 

NOTE: Sampling sections, labeled with single letters, and drill holes, which all start with U, are indicated on the 
right and left sides of the figure, respectively. The stratigraphic units of the drill holes are given in Table 
11.4-2. 
Source: Simmons 2002 [157578] SN-LANL-SCI-215-V1, p. 6. 
Figure 11.4-1. Location Map of the Paiute Ridge Basaltic Intrusion Complex, Nevada Test Site 

NOTE: These veins are within 8 ft (2.4 m) from the basaltic intrusion contact adjacent to 
the Papoose Lake Sill in the northern part of Paiute Ridge. The vein zone is 
about 25 ft (7.6 m) wide. 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p.44, Figure 16B. 
Figure 11.4-2. Anastomosing Opal Veins Adjacent to the Papoose Lake Sill 

NOTE: Calcite veins along fractures and cavities and epidote grains in cavities are present in 
the photomicrograph of basalt (LANL# 3547) (view is 170 x 255 m). 
Source: Simmons 2002 [157578], SN-LANL-SCI-215-V1, p. 130. 
Figure 11.4-3. Photomicrograph of Basalt from the Contact Zone 
of the Papoose Lake Sill in the Northern Part of Paiute Ridge 

NOTE: This sample (LANL# 3557) was collected 43 ft (13.1 m) from the Papoose 
Lake Sill contact. Brighter patches of silica (left) and calcite (right) separated 
by opaque material replace the vitric matrix (view is 70 x 110 m). 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 131. 
Figure 11.4-4. Photomicrograph of Altered Rainier Mesa Tuff 

NOTE: Map not to scale; compiled from field notes; see Table 11.4-1 for sample 
descriptions and measured distances from sill margin. 
Source: Simmons 2002 [157578], SN-LBNL-SCI-108-V2, p. 23. 
Figure 11.4-5. Schematic Map of Location H, Papoose Lake Basaltic Sill, Paiute Ridge, Nevada Test Site 

NOTE: This sample of nonwelded Rainier Mesa Tuff (LANL# 3559) was collected 200 ft (61 m) from the 
basaltic sill contact. It is apparent that the vesicles are devoid of secondary minerals from 
devitrification after deposition or from the hydrothermal process related to the basaltic intrusion. 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 101. 
Figure 11.4-6. Scanning Electron Microscope Image of Vesicles in Nonwelded Rainier Mesa Tuff 

45 
50 
55 
60 
65 
70 
75 
80 
85 
0 100 200 300 400 500 
Distance (ft) 
SiO2 (%) 
0 
0.02 
0.04 
0.06 
0.08 
0.1 
0.12 
0.14 
0.16 
0.18 
0.2 
0 100 200 300 400 500 
Distance (ft) 
TiO2 (%) 
0
2
4
6
8 
10 
12 
14 
0 100 200 300 400 500 
Distance (ft) 
Al2O3 (%) 
0 
0.2 
0.4 
0.6 
0.8
1 
1.2 
1.4 
0 100 200 300 400 500 
Distance (ft) 
Fe2O3 (%) 
0
1
2
3
4
5
6 
0 100 200 300 400 500 
Distance (ft) 
CaO (%) 
0 
0.5
1 
1.5
2 
2.5
3 
3.5
4 
0 100 200 300 400 500 
Distance (ft) 
Na2O (%) 
0
1
2
3
4
5
6
7 
0 100 200 300 400 500 
Distance (ft) 
K2O (%) 
NOTE: These variation diagrams use data in feet for distance and wt% for Na2O, K2O, 
Al2O3, CaO, SiO2, TiO2, and Fe2O3 of tuff samples from the northern part of 
Paiute Ridge. Major-element contents are calculated to 100% volatile free. Total 
iron reported as Fe2O3. Line indicates average composition of Rainier Mesa 
rhyolitic tuff reported by Broxton et al. (1989 [100024], Table 3). 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, pp. 63, 6976. 
Figure 11.4-7. Variation Diagrams of Distance Versus Na2O, K2O, Al2O3, CaO, SiO2, TiO2, and Fe2O3 

0 
40 
80 
120 
160 
200 
240 
280 
0 100 200 300 400 500 
Distance (ft) 
Rb (ppm) 
0 
100 
200 
300 
400 
500 
600 
700 
0 100 200 300 400 500 
Distance (ft) Sr (ppm) 
0 
40 
80 
120 
160 
200 
240 
280 
0 100 200 300 400 500 
Distance (ft) 
Zr (ppm) 
0 
10 
20 
30 
40 
50 
60 
0 100 200 300 400 500 
Distance (ft) 
Nb (ppm) 
NOTE: These variation diagrams use data in feet for distance versus ppm for Zr, Rb, Nb, 
and Sr of tuff samples from the northern part of Paiute Ridge. Line indicates 
average composition of Rainier Mesa rhyolitic tuff reported by Broxton et al. 
(1989 [100024], Table 3). 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, pp. 63, 6976. 
Figure 11.4-8. Variation Diagrams of Distance Versus Zr, Rb, Nb, and Sr 

NOTE: 500 m scale 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 128. 
Figure 11.4-9a. Tabular Crystal of Clinoptilolite Overgrowth on a Second 
Layer of Clinoptilolite with Scalloped or Serrated Edges (LANL# 3552) 

NOTE: This sample of Rainier Mesa Tuff (LANL# 3550) was collected 8.5 ft (2.6 m) from the Papoose 
Lake Sill contact in the northern part of Paiute Ridge. It is apparent that the cavity is partially filled 
by clinoptilolite. 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 100. 
Figure 11.4-9b. Scanning Electron Microscope Image of 
Clinoptilolite Crystal Aggregates in a Cavity of Rainier Mesa Tuff 

NOTE: This diagram of the half-space computational domain indicates the 
initial temperature of the intrusion of thickness L and tuff country rock 
for a one-dimensional simulation perpendicular to the intrusion. 
Source: Simmons 2002 [157578], SN-LBNL-SCI-108-V2, p. 22. 
Figure 11.4-10. Schematic Diagram of the Half-space Computational Domain 
0 
200 
400 
600 
800 
1000 
1200 
1 10 100 
TEMPERATURE [C] 
DISTANCE [m] 
Initial Temperature 
Fracture 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
0 
200 
400 
600 
800 
1000 
1200 
1 10 100 
TEMPERATURE [C] 
DISTANCE [m] 
Initial Temperature 
Matrix 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
NOTE: sfm = 102 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 112. 
Figure 11.4-11. Matrix (a) and Fracture (b) Temperature Profiles as a Function of Distance at the 
Indicated Times for the Dual-Continuum Model with Strong Fracture-Matrix Coupling 

0 
0.05 
0.1 
0.15 
0.2 
0.25 
0.3 
0.35 
1 10 100 
SATURATION 
DISTANCE [m] 
Initial Saturation 
Fracture 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
0 
0.2 
0.4 
0.6 
0.8
1 
1 10 100 
SATURATION 
DISTANCE [m] 
Initial Saturation 
Matrix 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
NOTE: sfm = 102 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 112. 
Figure 11.4-12. Matrix (a) and Fracture (b) Saturation Profiles as a Function of Distance at the 
Indicated Times for the Dual-Continuum Model with Strong Fracture-Matrix Coupling 

0 
200 
400 
600 
800 
1000 
1200 
1 10 100 
TEMPERATURE [C] 
DISTANCE [m] 
Initial Temperature 
Fracture 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
0 
200 
400 
600 
800 
1000 
1200 
1 10 100 
TEMPERATURE [C] 
DISTANCE [m] 
Initial Temperature 
Matrix 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
NOTE: sfm = 10-2 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 111. 
Figure 11.4-13. Matrix (a) and Fracture (b) Temperature Profiles as a Function of Distance at the 
Indicated Times for the Dual-Continuum Model with Moderate Fracture-Matrix Coupling 

0 
0.05 
0.1 
0.15 
0.2 
0.25 
0.3 
0.35 
1 10 100 
SATURATION 
DISTANCE [m] 
Initial Saturation 
Fracture 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
0 
0.2 
0.4 
0.6 
0.8
1 
1 10 100 
SATURATION 
DISTANCE [m] 
Initial Saturation 
Matrix 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
NOTE: sfm = 10-2 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 111. 
Figure 11.4-14. Matrix (a) and Fracture (b) Saturation Profiles as a Function of Distance at 
the Indicated Times for the Dual-Continuum Model with Moderate Fracture-Matrix Coupling 

0 
200 
400 
600 
800 
1000 
1200 
1 10 100 
TEMPERATURE [C] 
DISTANCE [m] 
Initial Temperature 
Fracture 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
0 
200 
400 
600 
800 
1000 
1200 
1 10 100 
TEMPERATURE [C] 
DISTANCE [m] 
Initial Temperature 
Matrix 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
NOTE: sfm = 10-4 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 110. 
Figure 11.4-15. Matrix (a) and Fracture (b) Temperature Profiles as a Function of Distance at 
the Indicated Times for the Dual-Continuum Model with Weak Fracture-Matrix Coupling 

0 
0.05 
0.1 
0.15 
0.2 
0.25 
0.3 
0.35 
1 10 100 
SATURATION 
DISTANCE [m] 
Initial Saturation 
Fracture 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
0 
0.2 
0.4 
0.6 
0.8
1 
1 10 100 
SATURATION 
DISTANCE [m] 
Initial Saturation 
Matrix 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
NOTE: sfm = 10-4 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 110. 
Figure 11.4-16. Matrix (a) and Fracture (b) Saturation Profiles as a Function of Distance at 
the Indicated Times for the Dual-Continuum Model with Weak Fracture-Matrix Coupling 

0 
200 
400 
600 
800 
1000 
1200 
1 10 100 
TEMPERATURE [C] 
DISTANCE [m] 
Initial Temperature 
Fracture 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
0 
200 
400 
600 
800 
1000 
1200 
1 10 100 
TEMPERATURE [C] 
DISTANCE [m] 
Initial Temperature 
Matrix 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
NOTE: sfm = 10-6 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 107. 
Figure 11.4-17. Matrix (a) and Fracture (b) Temperature Profiles as a Function of Distance at the 
Indicated Times for the Dual-Continuum Model with Very Weak Fracture-Matrix Coupling 

0 
0.05 
0.1 
0.15 
0.2 
0.25 
0.3 
0.35 
1 10 100 
SATURATION 
DISTANCE [m] 
Initial Saturation 
Fracture 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
0 
0.2 
0.4 
0.6 
0.8
1 
1 10 100 
SATURATION 
DISTANCE [m] 
Initial Saturation 
Matrix 0.5 y 
1 y 
10 y 
100 y 
500 y 
1000 y 
NOTE: sfm = 10-6 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 107. 
Figure 11.4-18. Matrix (a) and Fracture (b) Saturation Profiles as a Function of Distance at the 
Indicated Times for the Dual-Continuum Model with Very Weak Fracture-Matrix Coupling 

0 
0.02 
0.04 
0.06 
0.08 
0.1 
0.12 
0.14 
0.16 
0.18 
0.2
1e-12 1e-10 1e-08 1e-06 0.0001 0.01 1 100 
SATURATION 
TIME [y] 
-6 
-4 
-2
2 
Log sfm 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 118. 
Figure 11.4-19. Fracture Saturation as a Function of Time at the Boundary between 
the Intrusion and Country Rock for Different Fracture-Matrix Coupling Strengths 
DISTANCE [m] 
FRACTURE VOLUME FRACTION 
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 
0 
0.02 
0.04 
0.06 
0.08 
0.10 
0.01 
0.1 
0.5 
1
10 
TIME [y] efm=0.01 
NOTE: sfm = 10-2 
Source: Simmons 2002 [157578]; SN-LANL-SCI-215-V1, p. 117. 
Figure 11.4-20. Fracture Volume Fraction of Amorphous Silica Precipitation as a Function 
of Distance for Various Times with Moderate Fracture-Matrix Coupling 

12. ANALOGUES TO SATURATED ZONE TRANSPORT 
12.1 INTRODUCTION 
This section discusses analogues to transport in a saturated environment under oxidizing 
conditions, such as those at Yucca Mountain. Most of the analogue sites studied to date in 
saturated environments occur in rock types dissimilar to the saturated zone (SZ) at Yucca 
Mountain, e.g., fractured crystalline granite or gneiss, or sandstone. However, some aspects of 
these systems have attributes or demonstrate processes that warrant attention with respect to 
Yucca Mountain and are included in this section. Section 12.1 briefly summarizes the main 
conclusions of past Yucca Mountain Site Characterization Project (YMP) analogue studies with 
respect to SZ transport. Section 12.2 provides a background by describing the SZ flow system at 
Yucca Mountain. Section 12.3 is a study of transport plumes formed from uranium mill tailings 
at selected sites in the western United States and the relevance of this information to saturated 
transport in alluvium at Yucca Mountain. Section 12.4 provides examples from analogues of 
matrix diffusion and colloid transport in the SZ. The main ideas and conclusions are presented in 
Section 12.5. 
12.1.1 Insights into SZ Transport from Previous Analogue Studies 
Some of the processes relevant to radionuclide transport at saturated sites were discussed in 
Yucca Mountain Site Description (CRWMS M&O 2000 [151945], Section 13.4.3). The main 
points of those discussions are summarized here. 
Filtration of particulate matter is an efficient process at Poos de Caldas, Brazil 
(CRWMS M&O 2000 [151945], Section 13.4.3.3). The colloidal material acts as 
largely irreversible sinks for many immobile elements, such as thorium and rare-earth 
elements. 
The redox front at Poos de Caldas provided direct evidence of the operation of flow 
channeling in fractures and solute transport in the rock matrix as the key controls on the 
shape and movement of the redox front. The very slow, diffusion-dominated movement 
of the redox front plays a significant role in retarding many trace elements (CRWMS 
M&O 2000 [151945], Section 13.4.3.3; Romero et al. 1992 [157573], pp. 471472). 
Poos de Caldas also highlighted the importance of amorphous phases in suspension or 
as coatings on rock as the principal sorptive surfaces for many trace elements in 
solution (CRWMS M&O 2000 [151945], Section 13.4.3.3). Some of the fixing 
processes appeared to be irreversible over long time scales, compared to reversible 
sorption used in Performance Assessment (PA) models. Sorption onto fracture coatings, 
particularly calcite, also efficiently retards uranium transport in fractures at Palmottu, 
Finland (CRWMS M&O 2000) [151945], Section 13.4.3.3). 
The Chernobyl study (CRWMS M&O 2000 [151945], Section 13.4.3.3) showed that 
pathways of rapid groundwater contamination around Chernobyl may not be directly 
connected to the pathways of near-surface zones of preferential flow. 

Other analogues were mentioned as multiple lines of evidence in FY 01 Supplemental Science 
and Performance Analyses, Volume 1: Scientific Bases and Analyses (BSC 2001 [155950], 
Section 12.4). Using Yucca Mountain as a self-analogue, it was possible to interpret groundwater 
hydrochemical data to estimate flow paths in the vicinity of Yucca Mountain (BSC 2001 
[155950], Section 12.4.1). These estimated flow paths were shown to be consistent with flow 
paths predicted by the site-scale SZ flow model. 
The initial phase of investigation of the Uranium Mill Tailing Remedial Action (UMTRA) sites 
discovered that some fraction of the total inventory of uranium mill tailings appears to be 
transported as a nonsorbing to weakly sorbing species under oxidizing conditions (BSC 2001 
[155950], Section 12.4.2). This supported the TSPA-SR treatment of uranium as weakly sorbing 
(BSC 2001 [155950], Section 12.4.2). 
12.2 HYDROGEOLOGY AND FRACTURE MINERALOGY OF THE SATURATED 
ZONE 
The water table near the Yucca Mountain repository block is currently at an elevation of 
approximately 730 m, more than 300 m below the proposed repository horizon (DOE 1998 
[100548], Section 2.2.4). Water infiltrating the unsaturated zone (UZ) becomes recharge to the 
regional flow system. Water moves generally southeast beneath the (UZ) site before flowing 
south out of the volcanic rocks and into the thick valley fill of the Amargosa Valley. The 
hydraulic gradient is very low (~0.0001; Fridrich et al. 1994 [100575], p. 138) downgradient 
from Yucca Mountain, so that travel time of groundwater may be long. This is supported by 
isotopic data that indicates a Pleistocene age for Yucca Mountain groundwaters (Benson and 
McKinley 1985 [101036], p. 10). Near Yucca Mountain, volcanic rocks up to several thousand 
meters thick overlie the Paleozoic and older rocks of the region (DOE 1998 [100548], Section 
2.2.4.1). Their hydrologic properties change substantially over short distances, producing a 
complex hydrogeology. The volcanic-rock section becomes thinner to the south and is a lesser 
component of the saturated zone flow system in Amargosa Valley, where the major aquifer 
consists of Quaternary-Tertiary heterogeneous valley-fill deposits. 
The dominant regional aquifer is the Paleozoic carbonate aquifer, consisting of marine 
limestones, dolomites, and minor clastic sediments thousands of meters thick. In the vicinity of 
Yucca Mountain, the carbonate aquifer is not tapped as a source of groundwater because of its 
great depth (DOE 1998 [100548], Section 2.2.4.1). There is also overpressure; hence, upwelling, 
from the carbonate aquifer (Luckey et al. 1996 [100465], pp. 40-41). 
Luckey et al. (1996 [100465], pp. 1820) divided the volcanic rocks below the water table into 
four hydrogeologic units. From top to bottom, these are the upper volcanic aquifer, the upper 
volcanic confining unit, the lower volcanic aquifer, and the lower volcanic confining unit. The 
upper volcanic aquifer is composed of the Topopah Spring Tuff, which occurs in the UZ near the 
repository, but is present beneath the water table to the east and south of the potential repository 
and in Crater Flat. The upper volcanic confining unit includes the Calico Hills Formation and the 
uppermost, unfractured part of the Prow Pass Tuff in areas where they are saturated. The lower 
volcanic aquifer includes most of the Crater Flat Group (Luckey et al. 1996 [100465] pp. 1820), 
and the lower volcanic confining unit includes the lowermost Crater Flat Group and deeper tuffs, 
lavas, and flow breccias. The upper volcanic aquifer underlying Yucca Mountain is generally 

productive and provides groundwater for the site. The main distinction between SZ volcanic 
aquifers and confining units is that the aquifers tend to be more welded and contain more 
permeable fractures than the aquitards. However, alteration of the nonwelded tuffs to zeolites 
and clays, which reduces permeability, is more pronounced at depth. The increase of pressure 
with depth also reduces fracture permeability, such that the overall tendency is toward decreased 
permeability with depth, even in aquifers. 
The chemistry of SZ waters beneath Yucca Mountain (Oliver and Root 1997 [100069]) reflects 
processes that affected these waters as they flowed to the Yucca Mountain area from recharge 
areas to the north (McKinley et al. 1991 [116222]). In general, they are dilute sodium 
bicarbonate waters that are neutral to mildly alkaline and mildly oxidizing. Similarities between 
the composition of SZ waters in the recharge areas north of Yucca Mountain and those beneath 
Yucca Mountain suggest that water compositions primarily reflect water-rock interactions in the 
recharge areas (DOE 1998 [100548], Section 2.2.4.3). 
After reaching the water table, flow continues generally to the southeast away from the 
repository area. The majority of saturated flow occurs in zones with enhanced permeabilities 
caused by fractures. Retardation processes such as sorption, matrix diffusion, and dispersion also 
function in the SZ. Water may contact sorbing zeolites in the Calico Hills Formation and Prow 
Pass Tuff, and, as in the UZ, fracture minerals may have a significant effect on both flow and 
transport. 
Fracture-filling minerals in the SZ include smectite, manganese oxide minerals, hematite, quartz, 
opal-CT, calcite, and clinoptilolite and mordenite, the same zeolites that characterize the altered 
rock matrix below the water table (Carlos et al. 1995 [101326], pp. 812). Laboratory 
experiments have shown that fractures containing smectite, manganese oxides, and calcite have 
particular affinity for plutonium retention (DOE 1998 [100548], Section 2.2.5.2). Thus, 
analogues related to transport through saturated, oxidizing environments need to consider the 
role of fracture-filling minerals such as these in retarding the migration of radionuclides. 
12.3 URANIUM MILL TAILINGS 
12.3.1 Purpose and Approach 
This section summarizes pertinent information on the transport of uranium and other constituents 
of interest in alluvial aquifers at UMTRA sites. The YMP is particularly interested in the 
dispersion characteristics of the contaminant plumes and in the retardation behavior of 
constituents, such as uranium, that are found in nuclear waste to be emplaced in a repository. 
The scope of Section 12.3 is limited to a review of the subsurface transport behavior of uranium 
and other constituents of interest at UMTRA sites. All UMTRA sites have been evaluated to 
identify those sites appropriate for more detailed analysis. The emphasis here is on the transport 
behavior of uranium and other constituents in alluvial deposits. This is because the potential 
transport pathways from Yucca Mountain to the accessible environment pass through alluvium 
and because there are no UMTRA sites with bedrock similar to the volcanic rocks at Yucca 
Mountain. 

The approach is to evaluate the UMTRA sites in terms of aquifer materials, hydrologic 
characteristics, and groundwater chemistry. Those sites that are closest in hydrologic and 
chemical characteristics to the alluvium down gradient from Yucca Mountain and for which 
sufficient data are available for detailed transport analysis are considered in more detail. 
12.3.2 Background 
The UMTRA Project was authorized by Congress in 1978 to clean up 24 inactive uranium ore 
processing sites (DOE 1996 [154693]). Currently, there are 20 UMTRA Project sites in the 
continental United States, located mostly in the western states (Figure 12-1). Many of the sites 
are located in the Rocky Mountain states of Colorado (seven sites), Utah (three sites), Wyoming 
(two sites), New Mexico (two sites), and Idaho (one site). Sites are also located in Arizona (two 
sites), Oregon (one site), and Texas (one site) (DOE 2000 [157603]). 
Most of the sites consisted of a uranium processing mill with associated waste streams and ore 
and tailings piles. The ore and tailings piles were situated directly on surface soils. Rain and 
snow melt percolated through the piles, leaching uranium and other constituents before entering 
the underlying shallow groundwater systems. The UMTRA Project has monitored the 
concentrations of radionuclides and other contaminants in shallow groundwaters beneath and 
down gradient from these sites for 15 to 20 years. The information obtained provides useful 
insight on the fate and transport of uranium and related ore constituents in shallow aquifers. The 
information obtained on transport in alluvial aquifers could be particularly useful in the 
development of models and calculations for radionuclide transport in shallow alluvial aquifers 
down gradient from Yucca Mountain. 
12.3.3 Selection of Analogue Sites 
The magnitude of operations at the various UMTRA sites was quite variable. Sites such as Grand 
Junction, Rifle, and Naturita in Colorado had large operations that resulted in large tailings piles. 
Operations at Cannonsburg in Pennsylvania and Spook in Wyoming were much smaller, with 
correspondingly smaller tailings piles. Other sites were in between these two groups in terms of 
magnitude of operations and size of the tailings piles. The magnitude of the operation is 
important in this discussion, because the magnitude of the site-characterization activities 
undertaken by the UMTRA Project was generally proportional to the magnitude of the operation 
at a given site. To be useful to the Yucca Mountain Project, detailed site-characterization data are 
required on the flow and transport systems at these sites. Only a limited number of UMTRA sites 
have been investigated in sufficient detail to be of use as analogues to the transport of uranium 
and other constituents of interest in the alluvial part of the Yucca Mountain flow system. 
The history of operations at the various sites was also quite variable. Operations at the Old Rifle 
site started as early as 1924. Most of the sites started operation in the mid to late 1950s and 
ended operations in the early 1960s to early 1970s. During the 1980s and 1990s, the tailings piles 
located at the 24 sites were either capped in place or removed to another location and 
encapsulated. Therefore, the tailings piles were sources of contaminants for subsurface transport 
for, at most, 30 to 70 years. 

The ores processed at the various locations contained other chemical elements besides uranium 
and its daughter products. These elements included vanadium, arsenic, selenium, manganese, 
molybdenum, barium, and other trace metals. Most of these ore byproducts ended up in the 
tailings piles. In addition, chemicals used in processing the ore were also dumped on the tailings 
piles. Important among the latter were sulfuric acid, nitric acid, ammonium hydroxide, and 
organic complexing agents. While the mills were in operation, rain and melted snow infiltrated 
into the uncovered tailings piles and leached constituents from the tailings. Liquid spills or leaks 
from site operations also infiltrated into the subsurface. These spill, leak, and leach solutions 
have since percolated downward through the subsoils and sediments beneath the sites and 
reached groundwater, forming plumes of contaminants in shallow aquifers. Low-pH 
groundwaters resulting from addition of contaminants could have facilitated transport of 
uranium. In contrast, acidic groundwaters are not expected to be found at Yucca Mountain. 
Those UMTRA sites where the most extensive subsurface characterization and groundwater 
monitoring activities were performed are of the most interest to the YMP. The transport of 
contaminants in groundwater is controlled by numerous site-specific factors. Part of the value of 
UMTRA sites as analogues, therefore, is the site-specific information they can provide on the 
factors that control the transport behavior of important constituents such as uranium. Other 
parameters used to screen sites for more detailed discussion include the hydrogeology and 
hydrology of the shallow aquifers, and groundwater chemistry. The intent was to select sites with 
alluvial aquifers and low-ionic-strength groundwaters. The sites chosen for detailed discussion in 
this report are the Gunnison and New Rifle sites in Colorado. 
12.3.3.1 Gunnison, Colorado, UMTRA Site 
The following discussion is based primarily on information presented in the Final Site 
Observational Work Plan for the Gunnison, Colorado, UMTRA Project Site (DOE 2001 
[156666]) and Groundwater Hydrology Report, Attachment 3 of Remedial Action Plan and 
Site Design for Stabilization of the Inactive Uranium Mill Tailings Site at Gunnison, Colorado, 
Final (DOE 1992 [154692]). The Gunnison processing site is located adjacent to the city of 
Gunnison in Gunnison County, Colorado, on a drainage divide between the Gunnison River and 
Tomichi Creek in the Gunnison River valley (Figure 12-2). Uranium was processed at the site 
from 1958 to 1962. Approximately 719,000 yd3 (550,000 m3) of contaminated material including 
tailings were originally present on 68 acres (28 hectares). Between 1992 and 1995, the 
contaminated material was moved to the Gunnison disposal site, approximately 6 mi (10 km) 
from the processing site. 
The processing site was located on floodplain alluvium between the Gunnison River and 
Tomichi Creek. The site is about 0.4 mi (0.6 km) east of the Gunnison River and 0.4 mi (0.6 km) 
west of Tomichi Creek (Figure 12-2). It is bounded on the west by small storm drainage ditches 
and on the south and west by irrigation ditches. The climate at the site is semi-arid, with an 
average annual precipitation of 10.5 in. (27 cm), of which approximately half is contributed by 
snowfall (DOE 2001 [156666], Section 3.1). The average depth to groundwater beneath the site 
is 5 ft (1.5 m). The uppermost (unconfined) aquifer at the site is in the floodplain alluvium of the 
Gunnison River and Tomichi Creek. These alluvial deposits extend to at least 110 ft (34 m) 
beneath the processing site. The aquifer is recharged from rain, snowmelt, the Gunnison River, 
Tomichi Creek, and seasonal irrigation ditches around the site. The groundwater flows southwest 

at an average velocity of 270 ft (82 m) per year. Groundwater from beneath the site discharges 
into the Gunnison River and Tomichi Creek (DOE 1992 [154692], pp. 18-20). 
Tailings seepage has contaminated the alluvial groundwater beneath and downgradient from the 
processing site. Sulfuric acid was used extensively in ore processing at the site (DOE 1992 
[154692], p. 23). Because sulfate is a conservative constituent (i.e., is not retarded) in oxidizing 
groundwaters, it can be used to delineate the maximum extent of movement of site-related 
contaminants in groundwater. A sulfate plume has been delineated that originates at the site and 
extends approximately 7,000 ft (2,000 m) in a southwesterly direction (Figure 12-3). Even 
though the plume intersects, and possibly flows beneath, the Gunnison River, sulfate is 
conservative relative to uranium at this site. The inferred areal shape of the plume suggests only 
limited lateral dispersion over most of the length of the plume. A lateral pinching of the plume is 
also inferred by its shape. Borehole lithology logs show a local variation in unit thicknesses close 
to the narrowing of the plume. Here, the uppermost sand and gravel unit is about twice its 
thickness in adjacent boreholes and appears to fill a paleochannel cut into the underlying clayey 
sand and gravel unit (DOE 1992 [154692], p. 16). The highest concentration contours of both the 
sulfate and uranium plumes (DOE 1992 [154692], pp. 31, 35; Figures 12-3, 12-4) are tied to a 
water analysis from this location. Therefore, the widths of the plumes may be locally constrained 
by geohydrologic variations in the subsurface alluvial deposits. Interpretations of plume shape 
must be tempered by the fact that the number of sampling points available to construct the plume 
map was limited. The maximum concentrations of sulfate in groundwaters along the length of 
the plume show only limited variation (715378 mg/L). This suggests that downgradient dilution 
of contaminants originating at the processing site is limited. 
A uranium plume has also been delineated in association with the Gunnison site (Figure 12-4). 
The inferred plume has a shape and lateral extent very similar to the inferred sulfate plume 
(Figure 12-3). The similar shapes of the two inferred plume maps suggest that the narrow shape 
of the uranium plume is locally controlled by geohydrologic variations in the alluvium, described 
above, and not directly related to chemical conditions in the alluvial aquifer. For example, the 
possibility that lower uranium concentrations outside the inferred plume could simply reflect 
more reducing conditions that lead to the removal of uranium from groundwater is not supported 
by the data. The similarity in the lengths of the inferred uranium and sulfate plumes suggests that 
at least some of the uranium originating from the site may have been transported with little or no 
retardation. However, the groundwater concentrations of uranium decrease more rapidly with 
distance from the site than the sulfate concentrations. One possible explanation for the different 
concentration gradients is that the source terms increased with time. Another possible 
explanation is that the travel time for uranium was longer than the travel time for sulfate (i.e., 
that uranium was retarded to some degree). Laboratory data on sorption coefficients for uranium 
on alluvium from this area support the latter interpretation. The sorption coefficient values 
obtained for two alluvium samples were 1.70 and 5.24 mL/g (DOE 2000 [156666], Table 4-7). 
Note that dilution alone is not a likely explanation for the decreasing uranium concentrations 
downgradient, because sulfate concentrations do not decrease proportionately downgradient. 
In summary, the groundwater data for the Gunnison site yield several conclusions that may be 
significant with regard to radionuclide transport in alluvium at the Yucca Mountain site. To the 
extent that the hydrology of the alluvial aquifers at the Gunnison site and Yucca Mountain are 
comparable, the Gunnison data suggest that: (1) lateral dispersion may be very limited 

downgradient, (2) dilution may not be a significant process over the transport distance in 
alluvium, and (3) uranium may be only slightly retarded by interaction with aquifer materials. 
12.3.3.2 New Rifle Site, Rifle, Colorado 
The Rifle UMTRA site is located along the Colorado River approximately 90 miles (144 km) 
east of Grand Junction, Colorado. The Rifle site actually consists of two separate sites, known as 
Old Rifle and New Rifle. The Old Rifle site is located approximately 2.3 mi (3.7 km) 
northeast of the New Rifle site (Figure 12-5). The New Rifle site has been studied in greater 
detail and is for this reason the subject of this summary. The discussion in this section is based 
primarily on the Final Site Observational Work Plan for the UMTRA Project New Rifle Site, 
Volumes 1 and 2 (DOE 1999 [154687]). 
The New Rifle site processed uranium and vanadium ores from 1958 to 1984. The site is located 
within the broad alluvial floodplain of the Colorado River (Figure 12-6). The New Rifle site 
occupied much of the width of the Colorado River floodplain in a north-south direction 
(approximately 3,000 ft) (500 m), with the river located on the southern portion of the floodplain. 
The ore storage areas were located in the easternmost (upgradient) portion of the site, whereas 
the tailings pile was located in the western portion of the site. The mill and other buildings were 
located between the tailings pile and the ore storage areas. Approximately 3.5 million yd3 (2.7 
million m3) of contaminated material were present on 238 acres (96 hectares) at the site. The 
transfer of this contaminated material to a disposal cell was completed in 1996. 
The climate in the Rifle region is semi-arid, with an average total annual precipitation of 11 in. 
(28 cm) of which approximately one third is contributed by snowfall (DOE 1999 [154687], 
Section 3.2). The New Rifle site is underlain by 2030 ft (69 m) of alluvium deposited by the 
Colorado River (DOE 1999 [154687], Section 5.1.2.2). Unconfined groundwater is present at the 
base of the alluvium at a depth of 510 ft (1.53 m) below the ground surface. In general, 
groundwater flows west-southwest in the alluvium and in the underlying bedrock (DOE 1999 
[154687], Section 5.2.2). The alluvial deposits north of the river pinch out approximately 4 mi 
(6.4 km) to the southwest of the site (Figure 12-5). The alluvium is underlain by the Tertiary 
Wasatch Formation. The weathered upper few feet of the underlying Wasatch Formation also 
contain unconfined groundwater. Semiconfined and confined groundwater occurs in interlayered 
sandstone, siltstone, and claystone beds deeper in the Wasatch Formation. The hydraulic gradient 
in the deeper Wasatch Formation is upward (DOE 1999 [154687], Section 5.2.3). The major ion 
composition of waters in the unconfined aquifer is quite variable, largely because of seepage of 
contaminants from site operations. The downgradient groundwaters in the alluvial aquifer are 
primarily sodium-calcium sulfate waters. Upgradient (background) groundwaters tend to be of 
the sodium-calcium bicarbonate-sulfate-chloride type, similar to river waters and of much lower 
ionic strength than downgradient groundwaters (DOE 1999 [154687], Section 5.3.3). 
Processing operations at various locations on the site have resulted in the seepage of 
contaminants into the alluvial aquifer and the upper Wasatch Formation. The major sources of 
contaminated seepage were the mill and other processing buildings and vats, vanadium and 
gypsum ponds, evaporation ponds, and the tailings pile (Figure 12-6). The degree to which 
contaminants have migrated from various source areas on the site has been investigated with an 
extensive monitoring program that has been in place since 1985. Monitoring wells have been 

used to obtain water levels and water samples from the alluvial aquifer and from the Wasatch 
Formation. Monitoring wells that intersect the Wasatch Formation are located within ~0.25 mi of 
the operations area. The proximity of the uranium source term to the underlying bedrock aquifer 
with the upward hydraulic gradient and the disturbed nature of the UMTRA sites are two 
conditions that would not be analogous to transport at Yucca Mountain. 
The locations of the monitoring wells are shown in Figure 12-7. The site-related inorganic 
constituents most prevalent in the alluvial aquifer include ammonia, calcium, nitrate, 
molybdenum, selenium, sulfate, and uranium. Of these constituents, the transport behavior of 
uranium and selenium are of interest to the Yucca Mountain Project. Nitrate and sulfate are 
potentially of interest as conservative constituents, to trace the maximum extent of movement of 
contaminants from the site. However, the existence of reducing conditions in various wells 
downgradient from the site calls into question the use of nitrate as a conservative constituent. 
Organic constituents such as kerosene were also released to the alluvial aquifer, particularly in 
and around the processing buildings and vats. 
An estimate of the average extent of movement of contaminants from the site, without 
accounting for dispersion, can be obtained by calculating the distance groundwater could have 
traveled from the site since operations were initiated in 1958. The estimate is obtained using the 
following equation for the average linear groundwater velocity, Vx (Fetter 2001 [156668], 
p. 125): 
Vx = - K/ne(dh/dl), (Eq. 12-1) 
where K is the hydraulic conductivity, ne is the effective porosity, and dh/dl is the head gradient. 
The average hydraulic conductivity for the New Rifle site is reported as 114 ft/day (0.040 cm/s) 
(DOE 1999 [154687], Section 5.2.2), and was derived for the alluvial aquifer based on pump 
tests. The effective porosity was specified as 0.27. Based on water-level measurements taken in 
1998, the average gradient was found to be 0.0030. Substituting these values into the equation 
yields the following linear groundwater velocity: 
Vx = (-114 ft/day)/0.27(0.0030) = 1.27 ft/day 
A linear groundwater velocity of 1.27 ft/day (0.4 m/day) over a period of 40 years (19581998) 
leads to an estimated travel distance of 18,506 ft (5.64 km). 
Because the site operations covered most of the alluvial terrace in a north-south direction and 
because most of the contamination is in the alluvial aquifer, significant lateral dispersion of 
contaminated groundwater is precluded by the decreasing width of the alluvial deposits in the 
downgradient direction. However, the magnitude of the source term for different contaminants 
may have varied over the site. For example, uranium processing facilities were located in the 
northern portion of the site. Therefore, uranium concentrations might be expected to be highest 
in groundwater beneath this portion of the site. In fact, well 655, located near the northern end of 
the site fence shown in Figure 12-7, has the highest uranium concentrations in any of the wells 
sampled in the 1998 and 1999 sampling rounds (DOE 1999 [154687], p. 5-56). The absence of 
similarly high concentrations in downgradient wells suggests the operation of some dispersive 
process. In addition to lateral dispersion, vertical advective dispersion of contaminants in the 

alluvial aquifer may also occur. However, the saturated thickness of the alluvial deposits is only 
1020 ft (36 m) (DOE 1999 [154687], p. 5-19). Furthermore, the hydraulic gradient in the 
underlying Wasatch Formation is upward. These observations suggest that vertical advective 
dispersion of contaminants in the alluvial aquifer would be limited, but dilution may be an active 
process. 
The use of sulfuric acid in processing ores at the site [inferred to be common practice (Merritt 
1971 [156670], p. 29)] would have resulted in seepage to the vadose zone with high 
concentrations of sulfate and may have resulted in low-pH waters that would have facilitated 
uranium transport. The highest measured concentrations were observed in samples taken in the 
first two years of the monitoring program. The available data suggest that sulfate concentrations 
in groundwater beneath and downgradient of the site have generally been decreasing since 
approximately 1986, consistent with the fact that processing operations at the site ended in 1984. 
Analyses of groundwater samples from (background) wells in the Wasatch Formation located 
across the Colorado River and upgradient from the site indicate that these waters have lower 
sulfate concentrations than waters from the alluvial aquifer but substantially higher chloride 
concentrations. This suggests the SO4
2-/Cl- ratio may be useful in identifying groundwaters 
contaminated by site operations. Groundwaters from wells at background locations (DOE 1999 
[154687], Appendix C) show that SO4
2-/Cl- ratios in the Wasatch Formation are less than 2.0, 
with most less than 0.5. Water samples from the Colorado River have SO4
2-/Cl- ratios in the 
range of 0.75 to 0.85. As shown in Figure 12-8, most water samples from wells located on the 
site have SO4
2-/Cl- ratios in the range of 10 to 20. This ratio decreases with distance 
downgradient. The SO4
2-/Cl- ratio returns to near-background values at wells 220 and 172, the 
wells farthest downgradient. Thus, the maximum distance contaminants appear to have traveled 
from the site, based on the SO4
2-/Cl- ratio of alluvial groundwater samples, is approximately 
19,000 ft (5.8 km). This is similar to the maximum travel distance of 18,506 feet (5.64 km) 
calculated for groundwater based on hydraulic parameters. 
The observed decreases in the SO4
2-/Cl- ratios (Figure 12-8) and SO4
2- concentrations (6,000 to 
2,000 mg/L) in alluvial groundwater with increasing distance downgradient suggests that these 
waters are progressively diluted with waters that have low SO4
2-/Cl- ratios and low SO4
2- 
concentrations. Because there is an upward hydraulic gradient in the Wasatch Formation (DOE 
1999 [154687], p. 5-27) and because Wasatch Formation groundwaters from upgradient wells 
have low SO4
2-/Cl- ratios (< 0.5) and low sulfate concentrations (< 500 mg/L), the diluting waters 
most likely come from the Wasatch Formation. 
Measured uranium concentrations show a pattern similar to that observed in the SO4
2-/Cl- ratio 
data. Upgradient alluvial wells located on the eastern portion of the site have uranium 
concentrations between zero and 0.05 mg/L (Figure 12-9). Wells located near the former 
uranium processing buildings on site have the highest uranium concentrations of all water 
samples (0.4-0.5 mg/L). Note that waters with these uranium concentrations are undersaturated 
with respect to solid uranyl phases, as calculated by Jove Colon et al. (2001 [157472], p. 13, 14), 
for groundwater compositions typical of the New Rifle site. Uranium concentrations in alluvial 
groundwaters decrease downgradient and reach the 0.05 mg/L (background) level between 
10,000 and 15,000 ft (3-4.6 km) downgradient (Figure 12-9). Thus, it appears uranium has not 
traveled downgradient as far as sulfate, although the exact travel distance is difficult to quantify 
because background values show such a large range (0-0.05 mg/L). The uranium plume length 

based on the 1998 sampling data (34.6 km) is considerably greater than the 1 km length 
proposed by Jove Colon et al. (2001 [157472], p. 24) as the steady-state length for uranium 
plumes in groundwater systems (i.e., the length at which uranium concentration in monitoring 
wells remains fairly constant). In fact, there is no evidence in the New Rifle data that the 
uranium migration rate has decreased significantly with time, contrary to the conclusions reached 
by Jove Colon et al. (2001 [157472], p. 24). 
Taking the maximum distance traveled by uranium as 13,000 ft (Figure 12-9) and the maximum 
distance traveled by sulfate as 18,000 ft (Figure 12-8), an estimated retardation factor (Rt) for 
uranium of 1.38 (i.e., 18,000/13,000) is obtained. Using the retardation equation (Freeze and 
Cherry 1979 [101173], Equation 9.14) 
) 1 ( d b 
f 
.K Rt + = , (Eq. 12-2) 
where .b is the dry bulk density in g/cm3 and f is the porosity, we can solve for the sorption 
coefficient (Kd), 
( ) 
b 
t 
d 
R K 
. 
f 1 - 
= . (Eq. 12-3) 
Using values for the dry bulk density (.b) and porosity given for the alluvial aquifer in DOE 
(1999 [154687]), we obtain the following result for the uranium sorption coefficient (Kd): 
Kd = (1.38  1)0.25/1.52 = 0.06 mL/g. 
Batch-sorption coefficient measurements for uranium using alluvial materials from the New 
Rifle site and a synthetic groundwater show a range of coefficients from -0.31.4 mL/g, with an 
average value of 1.0 mL/g (DOE 1999 [154687], Table 4-6). The Kd calculated here falls within 
that range, but is lower than the mean average value. This difference may be partly accounted for 
by the fact that the calculated Rt is based on what may be closer to the maximum, rather than the 
average, distance traveled by uranium; therefore, the calculation yields a lower Kd. 
It is possible also that some uranium could have been transported downgradient as part of a 
colloidal phase (including microbes). Such colloidal transport could carry the uranium at 
essentially the velocity of groundwater. As part of the Nye County Early Warning Drilling 
Program, several monitoring wells have been installed down gradient of the potential repository 
at Yucca Mountain. Colloid transport is being studied through analyses of groundwater samples 
collected from these wells (Kung et al. 2001 [157604]). 
Selenium has been detected only in groundwaters from wells located within the boundaries of the 
original New Rifle site. There is no evidence of significant downgradient transport. This is 
probably a result of the combined effects of a smaller source term and higher sorption 
coefficients measured for selenium in contact with sediments from the alluvial aquifer (DOE 
1999 [154687], pp. 5-41, 5-42). 

In summary, the data available on uranium transport at the New Rifle UMTRA site suggest that 
dilution in the alluvial aquifer is a significant process downgradient from the site and that the 
sorption of uranium on alluvial sediments also occurs. 
12.3.3.3 Summary and Conclusions of UMTRA Study 
An evaluation of data available for 24 UMTRA sites determined that only a few of these sites are 
potentially useful in the evaluation of transport of radionuclides in the alluvial portion of the 
Yucca Mountain flow system. Most of the sites are of limited use either because they are situated 
in a hydrogeologic setting different from Yucca Mountain or because there is insufficient 
information available to perform an adequate evaluation of transport behavior. There are enough 
data available for the Gunnison and New Rifle sites to perform a useful analysis. The 
conclusions derived from an analysis of the Gunnison site are (1) that a fraction of the uranium 
originating at the site is transported in the alluvial aquifer at a rate similar to the rate at which a 
conservative constituent is transported, and (2) there is little evidence for dispersion of 
contaminants in the downgradient direction. For the New Rifle site, the main conclusions are (1) 
that dilution is a significant process in the downgradient direction and (2) that uranium is 
transported at a slower rate than conservative constituents, although a fraction of the uranium 
traveled almost as far. The conclusions regarding uranium transport distances relative to 
conservative constituents must be tempered somewhat by uncertainties regarding the potential 
presence of unidentified complexing agents, such as organic materials, that could form colloids 
and enhance uranium transport. An additional note of caution attaches to the use of laboratory 
batch-derived Kd values for the prediction of large-scale field transport, because the two 
parameters are conceptually and numerically different. 
12.4 OTHER SATURATED ZONE ANALOGUES 
12.4.1 Uranium Retardation under Oxidizing Conditions 
Studies of the weathered zone overlying the Coles Hill, Virginia, uranium deposit indicate that 
the natural attenuation of uranium in oxidizing environments may occur in groundwaters with 
low dissolved carbonate/phosphate ratios (Jerden and Sinha 2001 [157474]). At the Coles Hill 
site, uranium concentrations are buffered to values <20 ppb due to the precipitation of lowsolubility 
U(VI) phases. The attenuation mechanism involves the transformation of U(IV) 
coffinite, the primary ore, to U(VI) phosphate minerals. Above the water table in the soil zone, 
where phosphate minerals are rare, uranium is primarily associated with an aluminum phosphate 
of the crandallite mineral group and with phosphorous sorbed to ferric hydroxide mineral 
coatings. Experiments demonstrated that the transformation of U(IV) to U(VI) assemblages 
could occur in less than two months, given high enough phosphate levels. Model predictions 
agreed with the field observations: for oxidizing systems with relatively low dissolved 
carbonate/phosphate ratios, uranium may be immobilized by secondary uranium phosphate 
precipitation and sorption processes. It is unlikely that low dissolved carbonate/phosphate ratios 
would occur in bedrock aquifers at Yucca Mountain, but if use of phosphate-containing fertilizer 
contaminates the alluvial aquifer in Amargosa Valley, the carbonate/phosphate ratio could be 
lowered, making this a more analogous situation for Yucca Mountain. 

12.4.2 Matrix Diffusion 
12.4.2.1 El Berrocal 
El Berrocal is an area approximately 100 km southwest of Madrid, Spain. The El Berrocal 
granite forms a large hill and contains a number of small, vein-hosted uranium ore bodies, one of 
which was the focus of analogue investigations (Figure 12-10). The El Berrocal granite has a 
uranium content that averages 16 mg/kg, with primary uranium occurring as accessory uraninite 
dispersed in the granite matrix (De la Cruz et al. 1997 [157473], pp. 8283). Post-emplacement 
hydrothermal alteration mobilized some of the uranium, thorium, and rare-earth elements from 
the granite and redeposited them in a 2-m-wide, steeply dipping quartz vein more than 1 Ma 
(Rivas et al. 1998 [126287], pp. 1516). Erosion and weathering exposed the vein-hosted 
mineralization, causing further elemental mobilization and transport. The groundwaters contain 
moderate to low concentrations of uranium (4  10-9 to 8  10-6 M) (De la Cruz et al. 1997 
[157473], p. 81; this converts to 9.52  10-4 to 1.9 mg/L). Uranium carbonate complexes are the 
dominant species in oxidized zones, whereas U(IV) hydroxides dominate in reduced zones. 
The multinational El Berrocal project had the objective of investigating these present-day, lowtemperature 
processes, as well as the processes responsible for elemental retardation in the 
granite. The results of the project indicated that mobilized uranium and thorium tended to be 
associated by sorption and coprecipitation with certain fracture-coating minerals, notably iron 
oxyhydroxides and calcite. Enrichment of uranium by a factor of up to 6 was observed, and up to 
3 for thorium, relative to the unaltered granite (Miller et al. 2000 [156684], p. 201). Considerable 
effort was made to understand these coprecipitation processes in order to improve 
thermodynamic models and databases for performance assessment (Section 15). 
12.4.2.2 Matrix Diffusion Comparison Studies 
The Palmottu, Finland, site in saturated, fractured gneisses and migmatites was the location of a 
matrix diffusion study. Radionuclide concentration profiles from a fracture in the rock matrix 
were examined in several different drillcores (Blomqvuist et al. 1995 [124640]). Alphaautoradiography 
showed the distribution of radionuclides decreasing from the fracture surface 
into the rock matrix. Based on the findings of three drillcore samples, the profile of decreasing 
radioactive content could be traced >100 mm into the rock (Blomqvist et al. 1995 [124640], 
pp. 6465). The radionuclides were associated with clay particles and iron oxyhydroxides that 
had formed from alteration of feldspar and biotite grains. Selective leaching experiments showed 
that most of the radionuclides that had diffused into the rock matrix were only loosely bound to 
the iron-rich phases. In some samples, activity correlated to microfractures indicated that fluid 
flow was channeled even at the microscopic level, whereas in another sample diffusion was 
predominantly along grain boundaries. This supports the hypothesis that physical disruption 
around a fracture may enhance transport into the rock matrix (Blomqvist et al. 1995 [124640], 
pp. 27, 60, 63, 64). 
A comprehensive investigation of matrix diffusion processes compared granite samples from a 
number of locations: the El Berrocal natural analogue site, Spain; the Stripa test mine, Sweden; 
the Whiteshell Underground Research Laboratory (URL), Canada; and the Grimsel Test Site, 
Switzerland (Heath 1995 [157478]). Each sample was taken from close to a hydraulically active 

fracture, cut to provide a series of slices parallel to the fracture, and characterized in detail. For 
all samples, the region of enhanced uranium mobility correlated with the zone of microstructural 
alteration in the rock adjacent to the fractures. The actual depth of enhanced uranium mobility 
varied from site to site; for instance, enhanced uranium mobility extended 35 mm in the shallow 
El Berrocal granite, but 50 mm in both the altered and unaltered URL granite. 
Interpretation of the El Berrocal core sample data indicated the following: not only was matrix 
diffusion limited to the first few tens of millimeters of rock adjacent to the fracture surface, but 
also within the rock matrix the mobilized uranium was associated with secondary phases and 
located in microfissures along grain boundaries (Heath 1995 [157478], p. 51). There was a very 
good correlation between the distribution of the mobilized uranium, the redox conditions, and the 
isotopic disequilibrium. Heath (1995 [157478], p. 51) concluded from a combination of all of the 
data that a complex combination of matrix diffusion and chemical interaction had occurred 
between the rock and the mobile phases, rather than matrix diffusion alone. From this 
conclusion, Heath suggested the possibility that retardation processes that rely on matrix 
diffusion mechanisms may make little overall contribution to performance in a crystalline rock 
mass. However, the data from El Berrocal provide good evidence that, once radionuclides 
migrate into the rock matrix from the flowing fracture, they are effectively immobilized 
irrespective of the process involved. 
12.4.3 Colloidal Transport in the SZ 
Colloids are ubiquitous in all groundwaters (McCarthy 1996 [157479], p. 197). However, in 
deep crystalline rocks with a stable geochemical system, the colloid concentrations are low, ~25 
g/L. In contrast, shallow aquifer systems generally appear to have the largest colloid 
concentrations, even in the presence of geochemical stability. Enhanced colloid concentrations 
occur in all rock types where there is some hydrogeochemical perturbation to the system. For 
example, in fractured granitic systems, colloid concentrations are 20 to 1,000 times higher in 
groundwaters affected by inputs of surface water or in hydrothermal zones with large 
temperature and pressure gradients, compared to stable hydrogeochemical systems (Degueldre 
1994 [101128]). 
The uptake and transport of radionuclides by colloids has been investigated in several analogue 
studies of natural systems with enhanced radionuclide content: Cigar Lake, Canada (Vilks et al. 
1993 [108261]); Alligator Rivers, Australia (Seo et al. 1994 [157480], p. 75); El Berrocal, Spain 
(Rivas et al. 1998 [126287]); and Poos de Caldas, Brazil (Miekeley et al. 1992 [106762]). In 
most of these studies, it was found that some proportion of the total uranium, thorium, and rareearth 
elements in the groundwater was associated with the colloids. This proportion was higher 
for thorium than for uranium because of thoriums lower solubility in most groundwaters. The 
rare earths generally show an affinity for colloids intermediate between uranium and thorium 
(Miekeley et al. 1992 [106762], pp. 429, 434). 
Unambiguous evidence from natural systems indicating colloid transport over long distances is 
rare. The only known example suggesting transport on the kilometer scale is at Menzenschwand, 
Germany, where the Ti:Mg ratio and rare-earth-element composition of the natural colloids 
differed from that of the host granite but were similar to that of a neighboring gneiss several 
kilometers away and upgradient (Hofmann 1989 [125081], pp. 925926). However, the flow 

system at Menzenschwand is not representative of a natural system, because it is perturbed by 
the presence of a uranium mine with associated fast flow. 
Many analogue studies suggest that colloid transport in natural systems is significantly restricted. 
For instance, at Cigar Lake, the uranium and radium contents of colloids in the ore and the 
surrounding clay zones are significantly higher than in colloids from the sandstone host rock, 
indicating that the clay is an effective barrier to colloid migration (Vilks et al. 1993 [108261]). 
Similar results at Alligator Rivers and Morro de Ferro also suggest that colloids have a limited 
capacity for migration, because the concentrations of colloid-bound radionuclides outside the 
orebodies are relatively low (Miekeley et al. 1992 [106762], pp. 420, 432433). 
Colloid concentrations of 0.86.9 mg/L for particles greater than 30 nm were observed in two 
wells on Pahute Mesa at the Nevada Test Site (NTS) (Buddemeier and Hunt 1988 [100712], p. 
537). One well was inside the Cheshire experimental site, and the second, a water well, was 300 
m away. Tritium, krypton, strontium, cesium, antimony, cobalt, cerium, and europium were 
detected in pumped water from the water well. All of the cobalt, cesium, and europium were 
associated with colloids in samples from both wells. Buddemeier and Hunt (1988 [100712], p. 
537) maintained that the presence of colloidal radionuclides outside the test cavity indicates 
radionuclide transport as colloids. 
In another study at the NTS (Kersting et al. 1999 [103282], p. 56), isotopic ratios of plutonium 
were used to fingerprint the source of plutonium detected in monitoring wells with a specific 
underground nuclear test, suggesting that the plutonium migrated a distance of 1.3 km. 
Plutonium has a tendency to strongly sorb to tuff minerals, which would retard its transport. 
Thus the observed presence of colloids in waters at the NTS and the observed association of 
plutonium with colloids were interpreted to indicate that radionuclide transport was expedited by 
colloids. However, the plutonium colloid concentration in the monitoring wells was very low. 
A similar conclusion was reported by Triay et al. (1997 [100422], p. 172) to explain the transport 
of plutonium and americium away from a low-level waste site in alluvial sediments at Mortandad 
Canyon at Los Alamos, New Mexico. These radionuclides were detected at depths of 30 m in 
monitoring wells in unsaturated tuff up to 3.4 km downgradient from the waste disposal site 
(Buddemeier and Hunt 1988 [100712], p. 536). The migration reportedly took place over a 
period of 30 years (Buddemeier and Hunt 1988 [100712], p. 536). Because sorption studies 
involving the alluvial sediments suggested that plutonium and americium should be relatively 
immobile, the observed movement of radionuclides was reported by Triay et al. (1997 [100422], 
p. 172) to suggest that the transport of plutonium and americium through alluvium resulted from 
association with highly mobile colloids. 
These observations lend support to the concept that radionuclide transport in the far field can be 
facilitated by colloids, but so far no natural analogue studies have been able to quantify the 
importance of this process over large distances. The analogue evidence suggests that colloids 
have a limited capacity for migration because the concentrations of colloid-bound radionuclides 
away from the source term are relatively low. 

12.5 CONCLUSIONS 
Insights from Yucca Mountain: Using Yucca Mountain as a self-analogue, it was possible to 
interpret groundwater hydrochemical data to estimate flow paths in the vicinity of Yucca 
Mountain. In addition, the Pleistocene age of groundwater provides a natural insight to check 
against calculations of groundwater travel times. 
UMTRA Study: Only a few of the UMTRA sites are potentially useful in the evaluation of 
radionuclide transport in the alluvial portion of the Yucca Mountain flow system. Most of the 
sites are of limited use either because they are situated in a hydrogeologic setting different from 
Yucca Mountain or because there is insufficient information available to perform an adequate 
evaluation of transport behavior. Enough data were available for the Gunnison and New Rifle 
sites to perform a useful analysis. The conclusions derived from an analysis of the Gunnison site 
are: (1) a fraction of the uranium originating at the site is transported in the alluvial aquifer at a 
rate similar to the rate at which a conservative constituent is transported, and (2) there is little 
evidence for lateral dispersion of contaminants in the downgradient direction. For the New Rifle 
site, the main conclusions are: (1) dilution is a significant process in the downgradient direction, 
and (2) uranium is transported more slowly than conservative constituents. The conclusions 
regarding uranium transport rates relative to conservative constituents must be tempered by 
uncertainties regarding the potential presence of unidentified complexing agents. 
Diffusion: Matrix diffusion in crystalline rock is generally limited to only a small volume of rock 
close to fractures, but even a small volume can make a significant difference in radionuclide 
retardation. 
Sorption onto fractures: Comparison of the results from a number of analogue study sites shows 
that similar sorption behavior is seen at many locations in crystalline rocks. For example, 
uranium and rare earth elements are frequently associated with calcite and iron oxyhydroxides. 
However, because it is often impossible to define in detail the paleohydrological history of a site, 
it is difficult to identify the unique effects of recent low-temperature retardation events. This is 
possibly the reason for the anomalous observations at El Berrocal related to limited observed 
uranium sorption on iron oxyhydroxides. 
Although several natural analogue studies have demonstrated the effect of sorption and 
precipitation processes on fracture surfaces, none has been able to distinguish clearly between 
these processes or to provide quantitative data on retardation with respect to transport of trace 
elements in natural waters. However, these studies do highlight which phases are most active, 
and they provide useful information on the effect of interaction between solutes and the rock 
surface. 
Colloid transport: In most studies of natural systems, it was found that some portion of the total 
uranium, thorium, and rare-earth elements in the groundwater was associated with colloids. 
Unambiguous evidence from natural systems indicating colloidal transport over kilometer-scale 
distances is limited to a few reports. Observations from such places as Los Alamos and the NTS 
lend support to the concept that radionuclide transport in the SZ can be facilitated by colloids, 
but so far no natural analogue studies have been able to quantify the importance of this process. 

Source: Modified from DOE 2000 [157603]. 
Figure 12-1. Locations of the UMTRA Groundwater Project Sites 
COLORADO 
DENVER 
10 0 
MILES 
20 
N 
GRAND JCT. 
DELTA
MONTROSE 
GUNNISON 
CRESTED BUTTE HOTCHKISS 
50 
50 
50 
133 
92 
141 
135 
550 
MESA CO. 
DELTA CO. 
GUNNISON CO. 
PITKIN CO. 
MONTROSE CO. 
BLUE MESA RESV. 
70 
COLORADO RIVER 
GUNNISON RIVER 
GUNNISON 
RIVER 
SITE 
Source: DOE 2001 [156666], Figure 1-1. 
Figure 12-2. Location Map for the Gunnison UMTRA Site 

Source: DOE 1992 [154692], Figure 3.10. 
Figure 12-3. Plume Map of Sulfate Concentrations (mg/L) in Alluvial Groundwater at the Gunnison 
UMTRA Site 

Source: DOE 1992 [154692], Figure 3.12. 
Figure 12-4. Plume Map of Uranium Concentrations (mg/L) in Alluvial Groundwater at the Gunnison 
UMTRA Site 

Junction 
Grand 
N 
70 
Denver 
Colorado 
6 
65 
Miles
20 10 0 
133 
30 
Site 
New Rifle 
Processing 
Rifle 
Colorado 
River 
13 
789 
Rifle 
Creek 
Glenwood 
Springs 
New 
Castle 
M:\UGW\511\0017\08\U00599\U0059900.DWG 06/4/99 8:59am ReynoldM 
Former 
Source: DOE 1999 [154687], Figure 1-1. 
Figure 12-5. Location Map for the New Rifle UMTRA Site 

Colorado R iver 
Evaporation Ponds 
Ore Storage 
Area 
I-70 Under 
Construction 
Northwest 
Tailings Pile 
Southwest 
Tailings Pile 
U.S. 
Highway 6 
Gypsum and 
Vanadium 
Ponds
U0047100-01 m:\u gw\5 11\0 01 7\08 \u 00 471 \u0 047 10 0.ap r reyn oldm 5/20 /199 9, 15 :2 2 
Source: DOE 1999 [154687], Figure 3-1. 
Figure 12-6. Aerial Photo of the New Rifle UMTRA Site, Showing Location of Tailings Piles (August 
1974) 
U 
U 
U 
U 
U 
S 
S 
S 
S 
S 
S 
S 
S 
S 
S 
S
S
S 
S
S 
S 
SS 
S 
S 
S 
S 
S 
S 
T 
T 
T
T 
T 
T T 
T 
T 
T 
T T 
T 
T 
T 
T 
T 
T 
T 
 
Mitigation wetland 
Roaring Fork holding pond 
 
Roaring Fork dewatering pit 
 
Colo 
rado River 
 
Site fence 
 
Extent of alluvium 
 
177 
214 
191 
190 
180 
175 
192 
183 
187 
182 
189 168 
185 
184 
174 
188 
186 
181 
178 
442 
217 
179 
170 
195 
197 
220 
213 
212 
171 
216 
215 
176 
219 
218 
210 
196 
201 
173 
172 
169 
200 
202 
211 
226 
225 
205 
208 
207 
206 
U0060200-01 
0 0.25 0.5 0.75 1 Miles 
N 
U 1998 Wasatch Well 
S 1998 Alluvial Well 
T Temporary 1998 Alluvial Well 
m:\ugw\511\0017\08\u00602\u0060200.apr reynoldm 7/1/1999, 16:14 
Source: DOE 1999 [154687], Figure 4-1. 
Figure 12-7. Map Showing Locations of Wells Screened in the Alluvial Aquifer at the New Rifle UMTRA 
Site 

0.0 
5.0 
10.0 
15.0 
20.0 
25.0 
0 5000 10000 15000 20000 
Distance in Feet 
SO4/Cl 
Source: DOE 1999 [154687], Appendix C. 
Figure 12-8. Sulfate/Chloride Ratios in Downgradient Alluvial Groundwater Versus Distance in Feet from 
the Colorado River Bank on the Eastern Edge of the New Rifle UMTRA Site 
0 
0.05 
0.1 
0.15 
0.2 
0.25 
0 5000 10000 15000 20000 
Distance in Feet 
Uranium (mg/L) 
Source: DOE 1999 [154687], Appendix C. 
Figure 12-9. Uranium Concentration in Downgradient Alluvial Groundwater Versus Distance in Feet from 
the Colorado River Bank on the Eastern Edge of the New Rifle UMTRA Site 

Source: Rivas et al. 1998 [126287], Figure 2-1. 
Figure 12-10. N-S Cross Section of the El Berrocal Granite-Uranium-Quartz Vein System and Location 
of Selected Boreholes 

13. ANALOGUE INFORMATION FOR BIOSPHERE PROCESS MODELS 
13.1 INTRODUCTION 
Section 13 presents information from the Chernobyl Nuclear Power Plant (ChNPP) accident in 
Ukraine that relates to parameters of interest in the Yucca Mountain Biosphere Process Model. 
Unlike the analogues presented in previous sections that dealt primarily with demonstrating 
confidence in processes and conceptual models, analogues relevant to biosphere models tend to 
focus on parameter input values. In Section 13.2, the Biosphere Process Model is briefly 
described to provide background against which to assess its information needs. Section 13.3 
focuses on studies of the Chernobyl nuclear accident and its consequences to the biosphere and 
their pertinence to the Yucca Mountain Biosphere Process Model. 
Although there are many contaminated sites that might have been suitable candidates for 
providing analogue information for the Biosphere Process Model, Chernobyl was selected for an 
in-depth survey. Chernobyl provides several advantages over other contaminated sites. First, the 
Chernobyl site was studied extensively after the 1986 accident, and a wealth of data has been 
published. Second, because the Chernobyl accident involved an explosion, data regarding the 
settling of contaminants following atmospheric transport resulting from the explosion provide a 
rather unique opportunity for use in adding confidence to the disruptive-event-pathway 
component of the Yucca Mountain Biosphere Process Model and Disruptive Event Biosphere 
Dose Conversion Factor Analysis (BSC 2003 [163958]). 
13.2 BACKGROUND 
13.2.1 Reference Environmental Conditions for the Yucca Mountain Biosphere Process 
Model 
The Yucca Mountain reference biosphere conceptual model is based on the biosphere 
environmental setting, including geography, climate, hydrogeology, geology, and soil conditions, 
as well as ecosystems (including human communities) (CRWMS M&O 2000 [151615], Section 
3.1.1). Yucca Mountain is located in a sparsely populated, semi-arid region in the transition 
zone between the Great Basin and the Mojave deserts. Yucca Mountain and surrounding areas 
are in the southern part of the Great Basin, the northern-most subprovince of the Basin and 
Range Physiographic Province. The topography, which is typical for the Great Basin, is 
characterized by relatively regularly-spaced mountain ranges and intervening alluvial basins, 
trending from the north to the south. The mountain ranges are formed by fault blocks that are 
tilted eastward, so that the fault-bounded west-facing slopes are generally high, steep, and 
straight, in contrast to the gentler and deeply dissected east-facing slopes. 
Yucca Mountain has low annual precipitation (from 100 to 200 mm) that decreases from the 
higher to lower elevations. About 50% of the annual precipitation falls from November through 
April, caused by large frontal storms. Summers are hot and winters are cool. The Sierra Nevada 
Mountains that lie to the west create a major barrier to moist air masses moving from the Pacific 
Ocean. Some thunderstorms in summer are able to create localized land surface flooding and 
runoff. The average maximum daytime temperature varies from 11C (52F) in January to 35C 

(95F) in July. Average nighttime temperatures are above freezing in January (2C [36F]), but 
winter freezing may occur. Average annual atmospheric humidity is less than 20%. Such 
conditions cause high evapotranspiration. Vegetation covers 20 to 30% of the ground, with 
shrubs dominating the native vegetation. 
The nearest settlement to Yucca Mountain is situated in the direction of groundwater flow in 
Amargosa Valley (Nye County). Amargosa Valley is an area of approximately 1,300 km2. The 
closest inhabitants to Yucca Mountain are approximately 20 km south at the intersection of U.S. 
95 and Nevada State Route 373. The Amargosa Valley population is about 1,270, with 
approximately 450 households. The Amargosa Valley region is primarily rural agrarian in 
nature, with agriculture mainly directed toward growing livestock feed (e.g., alfalfa), gardening, 
and animal husbandry. Both the agriculture and the population are concentrated in the Amargosa 
Farms area, approximately 30 km south of Yucca Mountain. Agricultural crops and gardens 
depend entirely on irrigation. Because there is no natural discharge of groundwater into the 
Amargosa Valley, the source of water for household uses, agriculture, horticulture, and animal 
husbandry is from local wells. Thus, the pathway for introduction into the biosphere is the use of 
wells for residential and agricultural purposes. 
The direction of groundwater flow is from north to south, with a discharge into the Amargosa 
Valley region located immediately to the south of Yucca Mountain. If radionuclides were to be 
released into groundwater or air at Yucca Mountain, groundwater flow and wind patterns could 
spread some contaminants into this region over time. 
Sandy-textured soils are found in Amargosa Valley. The active soil depth is 15 cm (with the 
tillage depth from 5 to 30 cm (BSC 2003 [163958], p. 13, Table 4.1-1), in which deposition of 
radionuclides from the atmosphere, irrigation, and resuspension may occur. The soil bulk 
densities in farming areas of Amargosa Valley range from 1.351.70 g/cm3, with a mean value of 
1.5 g/cm3 used in the Yucca Mountain Biosphere Process Model (CRWMS M&O 2000 
[151615], Section 3.2.4.1.3). 
13.2.2 Biosphere Process Model Pathways 
The Biosphere Process Model describes exposure pathways in the biosphere by which 
radionuclides released from a potential Yucca Mountain repository could reach a human receptor 
(Figure 13.2-1). The Yucca Mountain biosphere conceptual model considers two scenarios of 
possible radionuclide releases (CRWMS M&O 2000 [151615], Section 3.1.5). The first scenario 
assumes pumping of contaminated groundwater and use of this water in a hypothetical farming 
community (a) under undisturbed repository performance and (b) for some disruptive processes 
and events, such as volcanic activity, or through human activities such as drilling a borehole 
through a degraded waste container. Under the contaminated-groundwater scenario, infiltration 
through the unsaturated zone (UZ) or along a borehole would enable radionuclides to reach the 
saturated zone (SZ) followed by lateral spreading of radionuclides and pumping of contaminated 
groundwater. In this case, radionuclide-contaminated groundwater is used as the source of 
drinking water, irrigation, animal watering, and domestic uses (including gardening), thus 
increasing the likelihood of uptake by humans. The second scenario assumes that the release is 
caused by a volcanic discharge through the repository, leading to atmospheric dispersal of the 
contaminants into the accessible environment through ash fall, which accumulates on the land 

surface (BSC 2003 [163958], Section 1). These contaminants may then be absorbed by plants 
and digested and inhaled by animals and people at contaminated areas, thus entering the food 
chain and being made available for human consumption. Groundwater is assumed to be 
uncontaminated in the disruptive volcanic-event scenario. 
The Yucca Mountain Biosphere Process Model develops biosphere dose conversion factors 
(BDCFs), which are multipliers used in Total System Performance Assessment (TSPA) to 
convert the radionuclide concentration at the source of contamination into an annual dose, as 
defined by the regulator. 
13.3 USING CHERNOBYL DATA FOR EVALUATING BIOSPHERE PATHWAYS OF 
RADIONUCLIDES 
13.3.1 Relevance of Chernobyl Information 
Information about the distribution of radionuclides in the biosphere following the ChNPP reactor 
explosion in April 1986 is a valuable source of data for testing environmental transport models 
(Hoffman et al. 1996 [156616]; Konoplev et al. 1999 [156624]). The 1986 Chernobyl accident 
resulted from an explosion of the Fourth Reactor Unit of the ChNPP. Figure 13.3-1 shows the 
location of the ChNPP in the territory of Ukraine. The ChNPP accident resulted in 
contamination by a variety of radionuclides (89Sr, 90Sr, 95Zr, 99Mo, 103Ru, 106Ru, 134Cs, 137Cs, 
141Ce, 144Ce, 154Eu, 155Eu, 238Pu, 239 Pu, 240Pu, 241Pu, etc.) of large areas of the former USSR and 
the globe (Bar'yakhtar 1997 [156953], p. 35). Research into many environmental and health 
effects of the Chernobyl accident has become a major international enterprise aimed at 
understanding long-term transport processes and effects of exposure to radioactivity. A 
significant amount of data has been collected for the past 18 years about the distribution and 
accumulation of radioactive materials in different parts of the biosphere after the Chernobyl 
accident, including the main exposure pathways and mechanisms of radioactive contamination of 
the environment and the population. These data represent a valuable source of information to 
improve confidence in conceptual models of exposure pathways and processes. 
13.3.2 Objective and Approach 
Because direct observation of the actual outcome of the Biosphere Process Model scenarios will 
not be possible for many years, if ever (CRWMS M&O 2000 [151615], Section 3.2.3), one of 
the approaches to building confidence in biosphere models is to use information obtained from 
natural and anthropogenic analogue sites. As part of the model validation activities to improve 
biosphere models for both the groundwater-release and the volcanic-release scenarios, the Yucca 
Mountain Project is interested in measurements at specific locations to aid in selection of input 
data for models of specific environmental processes. 
The objective of Section 13.3 is to review information from the Chernobyl accident regarding the 
exposure pathways, inputs to risk assessment, and distribution of radioactive contaminants in the 
biosphere, to determine its potential relevance for the Yucca Mountain Biosphere Process Model. 
In particular, information was collected on the specific environmental processes of radionuclide 
transfer and resuspension, which could be used to improve confidence in the modeling of Yucca 
Mountain environmental processes. Major monographs and numerous articles were reviewed in 

English, Russian, and Ukrainian scientific and professional journals, magazines, and proceedings 
of international conferences and symposia. 
Taking into account the difference in climatologic and environmental conditions of Chernobyl 
and Yucca Mountain, this survey presents a broad picture of the environmental pathways of 
radionuclides in the biosphere. Radiation doses resulting from Chernobyl are presented as a 
means of illustrating the types of data available related to stated needs of the Yucca Mountain 
Biosphere Department, including the following: 
Radionuclide transfer from soil to plants via root uptake, soil to plants via atmospheric 
resuspension, and animal fodder to animal food products. 
Removal of contaminants via erosion and leaching. 
Inhalation of resuspended contaminants deposited on the ground. 
Radionuclide accumulation in soils and plants under irrigation using contaminated 
water. 
The ecological half-life of radionuclides in soils and plants. 
To be consistent with the Yucca Mountain analysis, Chernobyl data were analyzed using the 
same approach as that for Yucca Mountain: for the groundwater-contamination scenario, annual 
doses were estimated by multiplying radionuclide concentrations in groundwater by the 
corresponding BDCFs; and for the disruptive event scenario (which results in a surfacecontaminated 
source term), the doses are obtained by multiplying surface-activity concentration 
of a radionuclide by the corresponding BDCF (CRWMS 2000 [151615], Section 3.1.4). 
13.3.3 Chernobyl Accident and Main Exposure Pathways 
This section provides background for later discussion by describing the Chernobyl location, 
climate, and soil conditions; and the accident in terms of its explosion characteristics, radiation 
release, principal pathways, and types of particles released. 
13.3.3.1 Location, Climate, and Soil Conditions 
The ChNPP exclusion zone is located in the central part of the Ukrainian Polessye physiographic 
province. The term exclusion zone refers to an area surrounding the site that was sealed off as 
an institutional control to prevent further access after the accident. Immediately after the 
accident, the exclusion zone was established within the radius of 30 km from the ChNPP. 
However, as more measurements of the level of contamination over a larger territory were made, 
the boundary of the exclusion zone was adjusted to prevent access to highly contaminated areas. 
Its total area within the Ukrainian borders, except for part of the Kiev reservoir, is 2,044 km2 
(Shestopalov 1996 [107844], p. 3). 
The Chernobyl region has a humid climate, with mild, short winters and a warm summer. 
Average annual precipitation ranges from 550 to 750 mm/yr. The relief consists of slightly 
undulating plains and ridges, and irregularly located bogs. The relatively dense network of 
Pripyat and Dnieper River tributaries forms boggy valleys of moderate relief. Approximately 
50% of the land in the exclusion zone is covered by forest, 30% by arable farm land, and the 
remaining 20% by urban areas, marshlands, and water bodies (Shestopalov 1996 [107844], p. 

22). The soils are relatively homogeneous, with mostly podsols and peaty podsols (soils of 
forested, temperate climates) as the topsoil layer in the exclusion zone. 
13.3.3.2 Type of Explosion and Amount of the Radionuclide Release 
The initial explosion at Chernobyl was a steam explosion (Bar'yakhtar et al. 2000 [157504], 
pp. 1213; Tarapon 2001 [156920], p. 95). The total amount of radionuclides released by the 
accident into the environment expressed in becquerels (Bq) was approximately 11  1018 Bq 
(expressed in curies [Ci] this would equal 3  108 Ci), while approximately 6  1017 Bq (1.6  
107 Ci) of long-lived radionuclides remained in the destroyed reactor. (Note that 1 Ci = 3.7  
1010 Bq). The kinetic energy released from the accident has been estimated to be equivalent to 
3040 tons of trinitrotoluene (TNT) (Bar'yakhtar et al. 2000 [157504], p. 13). This was the 
highest single release ever of radionuclides into the global environment, with contamination 
calculated to be equivalent to that of a 12 Mt (megaton) nuclear explosion (Bar'yakhtar et al. 
1997 [156953], p. 224). No other nuclear accident approaches the dimensions of the Chernobyl 
disaster in terms of radiological release, acute radiation health effects, and socioeconomic and 
psychological impact (Bar'yakhtar et al. 2000 [157504], p. 9). 
The Chernobyl accident released approximately 2,000 Ci of isotopes of 239,240Pu into the 
atmosphere (Bar'yakhtar et al. 2000 [157504], Table 2.5.1). This amount of radiation is 
comparable to about 0.5% of the total global fallout of these isotopes from nuclear weapons 
testing from 1945 to 1963 (Bondarenko et al. 2000 [156593], p. 473). 
13.3.3.3 Principal Pathways 
The initial explosion and heat plume at Chernobyl carried volatile radioactive materials up to 1.5 
km (0.93 miles) in height, from where these materials were transported over large distances by 
prevailing winds (Figure 13.3-2). About a quarter of the total released radioactivity entered the 
atmosphere during the first day after the accident. By the fifth day, the release had decreased 
approximately six-fold, because of mitigation efforts at the ChNPP. The radionuclides that 
escaped into the atmosphere then migrated and settled in different areas, causing radioactive 
contamination of living things. Crops, vegetables, grasses, fruits, milk, dairy products, meat, and 
eggs were contaminated with radionuclides. The most severe radioactive contamination of 
fields, rivers, tributaries, canals, drainage ditches, and agricultural lands occurred in the Pripyat 
and Dnieper river basins that surround the ChNPP. 
As part of the cleanup effort after the Chernobyl accident, approximately 8  1015 Bq of high-, 
medium-, and low-level radioactive waste (mostly in solid form, such as construction parts, 
concrete, and soils) were accumulated and stored at more than 800 interim storage and disposal 
places in the region (Poyarkov 2000 [157503], pp. 12; Kukhar' et al. 2000 [157506]). 
Infiltration through unlined waste storage and disposal sites has caused leaching of contaminants, 
so these sites provide the current localized source term for soil and groundwater contamination 
(Shestopalov and Poyarkov 2000 [157507], pp. 146147). 
Figure 13.3-3 illustrates the principal pathways for radionuclides entering the biosphere through 
terrestrial and aquatic ecosystems after the Chernobyl accident. 

13.3.3.4 Types of Particles Released 
Two main types of radioactive particles were released from the damaged reactor: (1) a fuel 
component of finely dispersed fuel particles, containing elements of low volatility, such as 
cerium, zirconium, barium, lanthanum, strontium, and the actinides; and (2) a condensed 
component that formed when gases of nuclides (such as iodine, tellurium, cesium, and a lesser 
amount of strontium and ruthenium) that were ejected during the nuclear fuel fire, condensed on 
different surfaces (e.g., ground, buildings, and trees). 
Hot particles formed from both fuel and condensed components, including particles of uranium 
dioxide (a few tens of m in diameter or smaller) made of fuel fused with the metal cladding of 
the fuel rods and fuel mixed with sand or concrete (Loshchilov et al. 1991 [125894]; NEA 1995 
[156632], p. 53). Hot particles have an activity concentration exceeding 105 Bq/g (Bar'yakhtar 
1997 [156953], p. 235). Chernobyl hot particles behaved differently from nuclear bomb particles 
and Chernobyl gaseous and aerosol forms (Zheltonozhsky et al. 2001 [156630], p. 151). For 
example, Chernobyl hot particles (1) did not contain activation products such as 60Co; (2) 
contained 125Sb and 144Ce, which are absent in atomic bomb hot particles; (3) contained a larger 
fraction of 137Cs than that in nuclear bombs; (4) had a ratio of 154Eu/155Eu about 10 times greater 
than that in atomic bomb particles and about 200 times than that in fusion bomb particles; (5) 
have a lower radiation of uranium and neptunium than that from fusion bombs; and (6) had a 
lower plutonium content than that in fusion bombs (Zheltonozhsky et al. 2001 [156630], pp. 
156159). 
90Sr, 106Ru, 134Cs, 137Cs, 144Ce, and 147Pm contributed to the total -activity of hot particles (Papp 
et al. 1997 [124806], p. 951). Isotopes of actinide elements 238Pu, 239Pu, 240Pu, and 242Cm 
contributed mostly to the total a-activity of hot particles. The surface density of hot particles 
was about 1,600 per m2 in downtown Kiev (Papp et al. 1997 [124806], p. 951). Hot particles 
were detected not only on the surface, but they also migrated in soils to depths of about 0.5 m 
(Gudzenko 1992 [107835], p. 2), as detected in the fall of 1987 (Gudzenko et al. 1990 [125020], 
p. 122). 
The released fuel particles that entered the atmosphere are categorized by relative size into large 
(tens to several hundred m) and small particles (median radius of 1.53.5 m). The large fuel 
particles were formed from the fragmentation of the fuel at high temperatures during the initial 
phase of the accident. The large particles were primarily deposited within a 5 km zone around 
the damaged reactor. Small fuel particles consisted of unoxidized uranium dioxide (Bar'yakhtar 
et al. 2000 [157504], pp. 2122). Note that hot particles <10 m in size can be inhaled into the 
lungs (Loshchilov et al. 1991 [125894], p. 47). 
13.3.4 Soil Contamination 
This section provides an overview of the distribution of soil contamination resulting from the 
Chernobyl accident and characteristics of actinide element migration in soils. 

13.3.4.1 Lateral Distribution of Soil Contamination 
The prevailing wind directions and velocities that occurred immediately after the Chernobyl 
accident established the contaminant fallout trajectories (see Figure 13.3-2). The surface 
deposition of contaminants is affected mainly by local wind patterns and rain conditions existing 
at the time of the accident. Therefore, the surface contamination resulting from the Chernobyl 
accident is extremely irregular over very large areas. The contaminated spots range in size from 
a few square meters to more than a thousand square kilometers (Shestopalov 1996 [107844], p. 
14). The data on air transport of contaminants demonstrate the important role of the local spatial 
and temporal patterns in the wind direction and the need for estimating both the source strength 
and the lateral distribution of contaminants in numerical models (Goldman et al. 1987 [156820]). 
The area of highest concentration of 137Cs is the Western finger, which extends almost in a 
straight line westward from the ChNPP. The plume is 1.5 to 5 km wide; for a distance of <70 
km the concentration of 137Cs along its axis decreases from >10,000 Ci/km2 (3.7  105 kBq/m2) 
to 10 Ci/km2 (3.7  102 kBq/m2). Because of the local wind pattern, the Southern finger splits 
into five separate tracks and has the highest concentrations of 90Sr and actinides. The pattern of 
the widespread Northern finger was likely formed by deposition with rain. The South-West 
finger has the most complex, vortex-like shape (Shestopalov 1996 [107844], pp. 1314). 
The results of large-scale soil sampling on a regular grid of about 1 km (radius of 36 km) are 
shown on two maps of 90Sr and 137Cs contamination in Figure 13.3-4. The difference in 
distribution patterns for 90Sr and 137Cs is caused by different processes of precipitation for these 
radionuclides: 90Sr was ejected with fuel particles and precipitated mainly in the near ChNPP 
zone, while 137Cs was contained in the condensed component, which moved and precipitated 
further away from the ChNPP. These maps were used to estimate the total contents of 
radionuclides on the ground surface of the 30 km exclusion zone (without the reactor site and the 
radioactive waste disposal sites), which showed that initial estimates of the contamination were 
overestimated. For example, the content of 90Sr is estimated to be approximately 810 TBq (8.1  
1014 Bq) for the Ukrainian territory, which is 3 to 4 times lower than previous estimates 
(Kashparov et al. 2001 [157400], p. 295). 
13.3.4.2 Vertical Distribution of Radionuclides in Soils 
Silant'ev et al. (1989 [126508], p. 224), Isaksson and Erlandsson (1998 [156617], p. 150), and 
Likar et al. (2001 [156627], Figure 2) determined that, overall, the concentration of radionuclides 
in the soil profile decreases exponentially with depth to a depth of approximately 3 cm. In the 
exclusion zone, the downward velocity of migration of 137Cs ranged from 0.4 to 0.7 cm/yr in the 
first years after the accident, and then dropped to 0.2 cm/yr (Bar'yakhtar 1997 [156953], p. 247). 
Vertical migration of uranium and plutonium in soils is limited to the topsoil layer because these 
radionuclides were released as hot particles that are more or less stable in the near-surface 
weathered zone. Table 13.3-1 shows that about 99% of plutonium accumulated within the top 2- 
cm soil layer. This table also shows that the 238U/235U ratio remained unchanged below a depth 
of 3 cm. Figure 13.3-5 shows measurable quantities of actinides (plutonium, americium and 
curium) in soil to a depth of 4.5 cm, in Spring 1994, in the Kopachi village, located a few 
kilometers from the ChNPP (Mboulou et al. 1998 [156628]). Figure 13.3-6 shows the actual and 

predicted distribution of activities with depth for 90Sr, 137Cs, and 239Pu. The total activity of all 
these radionuclides is mostly in the upper 3-cm layer. 
Radionuclide releases from hot particles present an additional source of soil contamination, 
causing the concentration of mobile 137Cs in soils to reach a maximum 1.5 to 2.5 years after the 
accident and concentration of 90Sr to reach a maximum 6 to 15 years after the accident 
(Bar'yakhtar 1997 [156953], p. 243). The decrease in 137Cs concentration in soils in the 
exclusion zone by about 25%50%, as observed 10 years after the accident, was caused by 
several factors (Shestopalov 1996 [107844], p. 14): (1) natural radioactive decay of 137Cs (about 
20%); (2) partial washout of the soil surface layer from elevated areas and slopes; (3) soil 
decontamination; and (4) migration deeper than 20 cm from the soil surface along the zones of 
preferential flow. A secondary contamination by 137Cs affected many areas, such as local soil 
depressions, edges of marshes, and reservoir banks, where 137Cs concentration increased by a 
factor of 2 to 10 and locally up to 50 to 250 times. Concentration of 137Cs in the exclusion zone 
reached 50,000 to 150,000 Ci/km2, which is 5 to 15 times greater than that in soils in the socalled 
Red Forest around the ChNPP, where intense radioactivity caused leaves to lose 
chlorophyll and turn red. 
13.3.4.3 Characteristics of Migration of Actinides in Soils 
Within the European part of the former Soviet Union, the plutonium content in soils after the 
Chernobyl accident varies from 10 to 3,700 Bq/m2 (Lebedev et al. 1992 [125854], p. 516). The 
typical content of 239, 240Pu in Ukraine soils is 70 Bq/m2 (Bondarenko et al. 2000 [156593], p. 
473). The determination of the isotopic composition of plutonium, and especially the ratio 238Pu/ 
239, 240Pu, is important to assess the source of soil contamination. For example, for the global 
fallout, this ratio is typically from 0.03 to 0.05. However, in Chernobyl soil samples, this ratio 
varies from 0.25 to 0.35, which corresponds to the ratio of about 0.3 in spent fuel (Lebedev et al. 
1992 [125854], p. 517). In contrast to the radioactive gases and relatively mobile radionuclides 
such as iodine and cesium, isotopes of plutonium, americium, and other actinides are associated 
with fuel particles. 
Bondarenko et al. (2000 [156593]) presented the results of an 13-year investigation (198698) of 
the migration of long-lived a-emitting transuranic (TRU) elements in ecologic chains and the 
human body. The accumulation of TRU elements in plants showed significant variability, 
depending on the type of soil, vegetation, and presence of microbial activity. The ratio of 
concentrations of TRU elements in plants varies within several orders of magnitude among the 
isotopes of each element. The main pathways for the entrance of TRU elements in the human 
body are ingestion of food and water, and inhalation (Bondarenko et al. 2000 [156593], pp. 473 
474). Migration of TRU elements that accumulated in hot particles begins as hot particles are 
broken down. 
Thus, near-surface soil contamination by 90Sr, 137C, and TRU elements is widespread within a 
large area around Chernobyl, but vertical distribution of contaminants is mostly limited to depths 
of several centimeters. This creates favorable conditions for the atmospheric resuspension and 
secondary deposition, as described in Section 13.3.5, of hot particles and radionuclides attached 
to soil particles as a result of wind erosion. 

13.3.4.4 Technetium in Soils 
At present, there are only limited data on concentration of 99Tc in the environment caused by the 
ChNPP accident. Uchida et al. (1999 [156945]; 1999 [156925]) presented results of 99Tc 
measurements in soil samples collected within three forest sites around Chernobyl in 1994 and 
1995. Two sites were located 28.5 km and 26 km to the south, and one site is 6 km to the 
southeast of the ChNPP. The 99Tc concentration was determined by inductively coupled plasma 
mass spectrometry after its chemical separation from the soil sample. Concentrations of 99Tc in 
these soil samples ranged from 1.1 to 14.1 Bq/kg at a depth of 69 cm, which is one to two 
orders of magnitude higher than those under background conditions. The regression function 
describing the change of the 99Tc concentration with distance is 99Tc concentration = 
4.88  R-1.771, where 99Tc concentration on the ground is in GBq/km2 (Note: 1 GBq = 109 Bq) 
and the distance R is in kilometers from the ChNPP (Uchida et al. 1999 [156925], p. 2,764). 
The most stable form of technetium under aerobic conditions is Tc(VII), TcO4
-, which is 
characterized by high mobility in soils and availability to plants. Under anaerobic conditions and 
increased soil-water saturation (for example, under irrigation), TcO4
- could be transformed to a 
lower oxidation state of Tc(IV), to Tc sulfide forms, or to organic bound forms, which are 
insoluble and will adsorb and accumulate in soils with time (Tagami and Uchida 1999 [156923], 
pp. 963-964). 
13.3.5 Erosion and Atmospheric Resuspension of Radionuclides 
After the Chernobyl release ended, atmospheric resuspension of radionuclides became a 
secondary source of contamination, which affected people in areas that were not exposed to the 
original release (Garger et al. 1996 [156602], p. 18). The main cause for the resuspension of 
radionuclides is wind erosion of soil. 
Resuspension of radionuclides with dust driven by wind is especially hazardous in agricultural 
areas. The resuspension of particles with 137Cs increases after the tillage of agricultural lands 
from background conditions. 
One of the main parameters characterizing the atmospheric resuspension of radionuclides is the 
resuspension factor. The resuspension factor is defined as the ratio between the airborne (Bq/m3) 
and surface (i.e., <1 cm depth) concentration (Bq/m2) of a radionuclide in question. According to 
Bondarenko et al. (2000 [156593], pp. 474475), the resuspension factor in 1998 ranged from 
0.34  10-1017  10-10/m. This value is in agreement with the range of resuspension factors 
(from 1.4  10-10/m for 137Cs and 1  10-11/m for 239,240Pu) determined in 1998 by Rosner and 
Winkler (2001 [156629], pp. 11, 17). The resuspension factor was higher at the earlier stage 
after the accident. For comparison, in the Yucca Mountain Biosphere Process Model, the 
resuspension-factor mean value is 8.3  10-11/m (CRWMS M&O 2000 [151615], Section 
3.2.4.1.3). 
Kashparov et al. (2000 [156622]) investigated the resuspension and redistribution of 
radionuclides at various distances from fires occurring in areas previously contaminated by the 
Chernobyl accident and outside the 30 km ChNPP exclusion zone. They determined that the 
resuspension factor for the active phase of a fire was as high as 10-710-8/m (Kashparov et al. 

2000 [156622], p. 288). The dose coefficient from the radioactive aerosol inhalation was 
estimated to be 1.5  10-8 Sv (1 Sv = 100 rem), which provides less than 1% of the total dose 
resulting from inhalation and external radiation (Kashparov et al. 2000 [156622], p. 296). This 
value for the dose coefficient was obtained for a one-year period following a single intake of 
radionuclides due to a fire (Kashparov et al. 2000 [156622], p. 297). Equivalent dose is the 
quantity obtained by multiplying the absorbed dose (the quantity of energy imparted by radiation 
to a unit mass of matter such as tissue, measured in SI (International System of Units) units in 
grays, Gy, or rad) in a body organ or tissue by a factor representing the effectiveness of the type 
of radiation causing harm to the organ or tissue (NEA 1995 [156632], p. 60). Effective dose is 
the weighted sum of the equivalent doses to the various organs and tissues, multiplied by 
weighting factors reflecting the differing sensitivities of organs and tissues to radiation (NEA 
1995 [156632], p. 59). In SI units, equivalent dose is measured in sieverts (Sv). The whole-body 
(internal and external) dose (i.e., total effective dose equivalent [TEDE]) limit for a radiological 
worker is 5 rem/year (DOE 1994 [104736], p. 2-6, Table 2-1). The presence of a-emitting 
radionuclides (in the 30 km zone) causes a considerable increase in inhalation dose during forest 
fires, which can exceed external exposure doses (Kashparov et al. 2000 [156622], p. 297). 
Thus, measurements and modeling investigations indicated that radionuclide resuspension could 
become a source of both external and inhalation radiation doses for people, depending on the 
distance from the release. The size distribution of resuspended particles is important in 
determining inhalation (i.e., lung) dose. 
13.3.6 Groundwater Contamination 
This section examines the extent of groundwater contamination resulting from the Chernobyl 
accident and the type of radionuclides involved. 
The largest source of radionuclide contamination of groundwater is from about 800 radioactive 
waste disposal sites within the Chernobyl exclusion zone. Another large, local source of 
contamination is the Chernobyl cooling pond (Shestopalov and Poyarkov 2000 [157507], 
p. 146). Radionuclides dispersed over large areas can migrate to the water table through and 
around casings of boreholes and in colloidal and dissolved states in percolating water from the 
vadose zone. Field investigations showed a lack of correlation between 137Cs soil concentration 
and its travel time to the water table (Gudzenko et al. 1991 [107834], p. 3), indicating that soil 
contamination is not a major source of groundwater contamination. 
Before the Chernobyl accident, the depth to the water table around the ChNPP was 
approximately 6 to 8 m and was controlled by several drainage systems. Since 1986, some 
drainage systems have been abandoned, so that the water table has risen, creating a potential 
instability for the remaining structure of the ChNPP. Subsequently, several countermeasures, 
such as the construction of a vertical drainage system and an impermeable underground vertical 
wall, allowed the water table to decline to previous depths. 
The highest 90Sr concentrations of groundwaters (102104 Bq/L) were measured in water samples 
taken at interim radioactive storage sites near the ChNPP (Table 13.3-2). By 19951996, an 
increase in the 90Sr and 137Cs concentrations by 23 orders of magnitude, in comparison with 
pre-accident conditions, occurred in the upper section of groundwater within the inner part (510 

km) of the exclusion zone. At the same time, radionuclide concentration in the groundwater and 
the artesian aquifer are below the maximum permissible concentration. Despite a low level of 
current contamination of the artesian aquifer in the Eocene deposits, which is the source of 
potable water within the exclusion zone, it is predicted that groundwater contamination will 
increase over the next few decades (Shestopalov and Poyarkov 2000 [157507], p. 141). 
The presence of 134Cs in groundwater and the increase of 90Sr concentration by two orders of 
magnitude (from 4400 mBq/L) confirm that radionuclides from Chernobyl reached 
groundwater at 50 to 70 m depths over five years (1987-1992) (Bar'yakhtar 1997 [156953], p. 
254). Cs-137 and 90Sr contamination was detected in the Cretaceous aquifer at depths of 80 to 
120 m within the 30 km zone 22 months after the accident (Gudzenko 1992 [107835], p. 5). 
Elevated concentrations of 90Sr and 137Cs occurred at substantial distances from the ChNPP plant 
in all aquifers down to 200300 m (Table 13.3-3). 
Given these findings, groundwater contamination by 90Sr and 137Cs, caused by leakage from 
radioactive waste disposal sites within the Chernobyl exclusion zone, cooling pond, and 
migration through casings of boreholes to depths below 120 m, is expected to influence all 
nearby aquifers. However, the risk associated with the use of contaminated groundwater water 
for water supply is marginal, as compared to external radiation and inhalation doses (see 
Sections 13.3.7 and 13.3.9). 
13.3.7 Using Contaminated Water for Irrigation and Water Supply 
The Dnieper River water is used for irrigation of more than 1.8 million hectares in Ukraine, 
involving the territories from Kiev in the north to Crimea in the south (Berkovski et al. 1996 
[156592], p. 39). Figure 13.3-8 shows the concentration of radionuclides in water from six 
reservoirs along the Dnieper River used for irrigation. In the southern Ukraine, which has a semiarid 
climate and a depth to the water table of 5070 m, irrigation water is taken mostly from 
canals extending from the Dnieper River reservoirs. About 50% of the land is used to plant 
fodder crops, eventually leading to the contamination of meat and milk products, and about 10% 
is used to plant vegetables (Berkovski et al. 1996 [156592], p. 39). The water loss into the 
subsurface on irrigated lands and from irrigation canals accelerates migration of the radioactive 
elements from crops, soil surface, and surface water sources into the vadose zone and 
groundwater. The amount of radionuclides migrating into the subsurface depends on the quality 
(pH and chemical composition) of the irrigation water and soils, soil structure, depth to water 
table, and evapotranspiration, as well as the type of irrigation. 
Table 13.3-4 illustrates that the concentrations of 137Cs in grains, grass, and vegetables grown on 
lands that were irrigated with contaminated Dnieper River water exceeded by a factor of 26 
those in crops irrigated using uncontaminated water, while the concentrations in irrigation water 
increased by a factor of 24 (Perepelyatnikov et al. 1991 [156822], p. 112, Table 5). The 
increase in the concentration observed during irrigation confirms the concept of a buildup factor 
in soils. 
Table 13.3-5 indicates that the accumulation of radionuclides on irrigated lands occurred to 
depths of at least 1020 cm. An example is data on the distribution of 137Cs and 90Sr in soils 
irrigated using contaminated water in the southern Ukraine (Perepelyatnikov et al. 1991 

[156822]). After the rice harvest in 1988, irrigation caused an increase in the 137Cs concentration 
in the 00.5 cm topsoil layer by 58% compared to that on unirrigated (bare) lands. In the 0.52 
cm layer, its concentration increased by 1419%. For the same time period, the 90Sr 
contamination increased by a factor of ~2 (from 1835 mCi/km2) in comparison with that of bare 
soil (i.e., without vegetation and irrigation). The accumulation of 137Cs and 90Sr in soils caused 
the concentration of these radionuclides in rice to increase. For example, in the first harvest after 
the accident in 1986, the 137Cs concentration increased by a factor of 1.6 compared to 1985 
concentrations. The 90Sr concentration began to increase in 1987, and it increased by a factor of 
1.3 compared with 1985 values. However, in the southern Ukraine, concentrations had not 
reached levels detected in 1972 from global fallout generated by nuclear testing (Perepelyatnikov 
et al. 1991 [156822], pp. 110, 112, Table 4). 
Using the average concentrations of 137Cs and 90Sr in the 20 cm soil layer obtained after three 
years of rice irrigation (last column of Table 13.3-5) and concentrations in bare soils (third 
column of Table 13.3-5) assuming that the pre-accident concentration is equal to that of bare 
soils, the following buildup factors are obtained: for 137Cs, 0.48/0.37 = 1.3 (for three years), or 
approximately 10% per year; and for 90Sr, 116/60 = 1.97 (for three years), or approximately 32% 
per year. It is expected that the radionuclide buildup factor in soils under irrigation will change 
with time, depending on the processes of leaching and ecological decay of radionuclides. 
Thus, irrigation with contaminated water in the southern Ukraine leads to the accumulation of 
radionuclides in both the topsoil layer and in crops. The data obtained in Ukraine qualitatively 
confirm the concept of a radionuclide buildup factor in irrigated soils; this concept is employed 
in the Yucca Mountain Biosphere Process Model. 
13.3.8 Leaching and Transfer Coefficients 
This section discusses the dissolution rate, leaching parameters, soil-plant transfer of 
radionuclides, and radionuclide accumulation in fish and livestock. 
13.3.8.1 Dissolution Rate and Leaching Parameters 
Hot particles exposed at the surface were oxidized, which caused superficial cracking of the 
particles and increased their surface area, which in turn led to higher dissolution rates. The 
dissolution rates for nonoxidized and oxidized fuel particles (UO2+x) differ with acidity of the 
solution (Kashparov et al. 2000 [156623], p. 232). The dissolution rate V for fuel particles 
depends on the soil pH according to the formula (Baryakhtar et al. 2000 [157504], p. 32): 
V = a  10b pH m/yr (Eq. 13-1) 
where coefficients a = 14.45 and b = 0.431 for weakly oxidized particles, and a = 4.59 and b = 
-0.234 for strongly oxidized fuel particles. This formula was used to describe radionuclide 
leaching from fuel particles for pH from 4 to 6. Kashparov et al. (2000 [156623], p. 232, Figure 
4), who studied dissolution kinetics of Chernobyl fuel particles over a pH range from 3 to 9, 
determined that the dissolution rate is minimal in a neutral medium while it increases in both 
acidic and alkaline media. 

A study of concentrations of Chernobyl radionuclides in Neuherberg, Germany, was carried out 
by Rosner and Winkler (2001 [156629]). They determined that the annual mean concentrations 
in air and annual deposition to ground decreased for 90Sr, 137Cs, 238Pu, and 239,240Pu from July 
1986 to 1998. Figure 13.3-9 shows annual mean values of radionuclide concentrations in air 
(Bq/m3), specific activities in air dust (Bq/g), and radionuclide ratios in air (Bq/Bq) at Munich- 
Neuherberg since 1985. The air-dust concentration (g/m3) is shown in this figure for 
comparison. 
The leaching coefficient is defined as a parameter characterizing the downward movement of 
radionuclides dissolved in percolating waters (CRWMS M&O 2001 [152517], p. 6) and is 
calculated as part of the total mass of the radionuclide leached from a soil layer per unit of time 
(CRWMS M&O 2001 [152517], Section 5.1, Equation 1). 
The leaching coefficient for 90Sr determined using Chernobyl data varies significantly from 
3  10-23.1 L/yr (Bar'yakhtar 1997 [156953], p. 240). For comparison, the leaching coefficient 
for 90Sr used in the Yucca Mountain biosphere process model is 4.47  10-2 L/yr (CRWMS 
M&O 2000 [151615], Table 3-7), which is near the lower limit of the Chernobyl range. The 
dissolution rate of uranium reached 2.2  10-2 L/yr using Chernobyl data (Bar'yakhtar 1997 
[156953], p. 241). 
The release of radionuclides from solid particles into the soil is governed by the diffusion 
process (Sobotovich and Dolin 1994 [156821], p. 57). Given the diffusion coefficients for 90Sr 
(1.32.1  10-16 cm2/s) and 137Cs (2.54.8  10-17cm2/s), about 6580% of 90Sr will become 
mobile in 10 years, and only 2030% of 137Cs will become mobile over the same time 
(Sobotovich and Dolin 1994 [156821], pp. 59, 60). 
Smith et al. (2000 [156906], p. 141) hypothesized that the fixation process of radionuclides 
controls the amount of cesium in soil water and, therefore, its availability to terrestrial biota. The 
decline in 137Cs mobility and bioavailability over the first few years after fallout is most likely 
controlled by slow diffusion of 137Cs into the soils illitic clay mineral lattice. However, the 
sorption-desorption process may be reversible for 137Cs, in which case the ecological half-life 
increases towards its physical half-life decay rate of 30.2 years. Smith et al. (2000 [156906], 
p. 141) showed a two-component exponential decline model for the 137Cs decline in vegetation, 
water, and fish. 
13.3.8.2 Soil-Plant-Food Transfer of Radionuclides and Food Contamination 
Two main mechanisms control radionuclide transfer to plants: (1) direct deposition on plant 
surfaces from atmospheric resuspension of contaminated soil and from irrigation with 
contaminated water, and (2) the root uptake of radionuclides. For example, immediately after 
the Chernobyl accident, when aerosol particles accumulated only on the outer bark of trees, the 
radioactivity of leaves of some trees in the streets of Central Kiev in 1986 varied from 70,000 
400,000 Bq/kg (Baryakhtar 1997 [156953], pp. 260, 261). At that time, inner tissues of trees 
and roots did not pick up contamination. Radioactivity of the outer bark of trees decreased in 56 
years after the accident, while the activity in wood and inner bark increased because 
contaminants migrated through the root systems. Root uptake became significant the second 
year after the accident. 

The soil-to-plant transfer factor (or concentration ratio) is defined as the ratio of radioactivity 
concentration in the edible part of the plant (Bq/kg) to the radioactivity concentration in soil 
(Bq/kg). This factor is also termed the accumulation factor by Bar'yakhtar (1997 [156953], p. 
270). Table 13.3-6 compares the soil-to-plant-transfer factors for different radionuclides in the 
Yucca Mountain Biosphere Process Model with those in Chernobyl. The range of these factors 
for each element depends on many processes affected by the type of elements and soil properties, 
plant species, concentration of nutrients and carrier elements in soils, moisture content, acidity of 
soils, and meteorological and climatic conditions. 
The soil-plant transfer processes are not important for short-lived radionuclides, such as 131I, 
because they essentially decay before being taken up by plant roots. The transfer of 
radionuclides from soils to plants is limited to long-lived radionuclides. However, the soil-plant 
transfer is a predominant pathway for cesium and strontium to appear in pasture and/or fodder, 
and subsequently in meat and milk, thus becoming part of the exposure pathway. Table 13.3-7 
summarizes the values of the cesium soil-to-fodder transfer coefficients, depending on the soil 
pH and types of agricultural products. This table shows that transfer factors for 137Cs vary 
significantly (several orders of magnitude), depending on types of soils and plants, presumably 
because of the effects of microbiological activity in soils (metabolism and decay of 
microorganisms) and in the presence of different complex-forming ligands. 
A plausible explanation for the observation in Table 13.3-7 that transfer coefficients are higher in 
natural grasses than in other fodder types could be the following. The transfer coefficients 
depend on the diffusion of radionuclides into the root system. Natural grasses grow on 
undisturbed soils with better contact between the soils and roots, which increases the diffusion of 
radionuclides into grasses. In contrast to undisturbed soils, cultivated soils do not have as good 
contact with the roots, which reduces diffusion of radionuclides into the plants. At the same 
time, cultivated soils experience more significant weathering and resuspension of radionuclides 
by wind. Furthermore, application of fertilizers to cultivated soils and soil-plant microbiological 
activity may immobilize radionuclides. 
The effective meadow-vegetation transfer coefficient for 90Sr is of the same order of magnitude 
as in alfalfa, and is shown in Figure 13.3-10. Accumulation of 137Cs in vegetables (cucumber 
and tomato) is higher than in wheat and corn (see Table 13.3-4). Accumulation of 137Cs in some 
meadow grasses depends on the type of soils and increases in wet soils (Shestopalov and 
Poyarkov 2000 [157507], Table 5.6.3). The data given in this figure can be used to estimate that 
the transfer coefficient for 90Sr increased from 1  10-31  10-2 m2/kg from 1988 to 1994. This 
increase can be explained by the fact that 90Sr, which settled on soils, is gradually transformed 
into a soluble form and thus absorbed by plants. 
Bruk et al. (1998 [156600], p. 178) determined that during the first five to six years after 
deposition, the 137Cs concentration in vegetables and animal agricultural products decreased with 
an environmental half-life period of 0.71.5 years (i.e., the length of time required for  of the 
radioactivity to decay in situ). Thereafter, beginning from 19901991, no significant variation of 
the 137Cs content in food products was found, and the values of the transfer factors for this 
radionuclide in the main types of food (milk, potatoes) for rural inhabitants were close to those 
obtained in the pre-accident period (19801985), based on the global origin. Reduction of the 
137Cs content in produce was most rapid during the early years after the accident, as intensive 

countermeasures were applied at that time. Half-life periods for 137Cs content in milk (the basic 
dose-forming product) and other products for the most contaminated areas in Russia amounted to 
1.64.8 years, depending on the type of countermeasures used. Half-life periods of the decrease 
in the 137Cs content in other types of agricultural products (grain, potato) were within the range 
of 27 years. Ivanov (2001 [156818], pp. 6566) approximated the dynamics of the transfer 
coefficient for 137Cs in the chain soil-plant by a function 
y = a exp(-bt) + (1-a) exp(-ct) (Eq. 13-2) 
where y is the transfer coefficient normalized to the maximum transfer coefficient, t is the time 
(in years), and a, b, and c are parameters that depend on the type of soil and plants: a = 0.76 
0.94, b = 0.441.38, and c = 0.0380.17 (Ivanov 2001 [156818], p. 67, Table 5). According to 
Ivanov (2001 [156818], Table 6), the ecological half-life of 137Cs in agricultural plants varied in 
terms of averaged values from 0.42 (first period) to 22.1 (second period) years, depending on the 
type of soils. Figure 13.3-11 presents the dynamics of the transfer coefficient for 137Cs in 
meadow grass. 
Zhdanaova et al. (2000 [156951], p. 64) determined that interaction between biota and 
micromycetes fungi destroyed hot particles after the Chernobyl accident. They determined two 
mechanisms responsible for these processes: (1) microbial metabolic activity; and (2) mechanical 
destruction by mycelial overgrowth of radioactive particles. From this, it follows that these 
processes may also decrease the half-life of radionuclides in the environment, compared with 
physical half-life values. Therefore, the use of physical values of the half-life of radionuclides 
gives conservative estimates of radionuclide migration in the Yucca Mountain Biosphere Process 
Model. 
Based on an extensive experimental and modeling study of transfer factors for mushrooms, wild 
animals, berries, meat, and milk in different regions of Ukraine, Belarus, and Russia, Jacob and 
Likhtarev (1996 [156864], p. 110) determined that a peroral (oral) dose is higher than that from 
the external radiation. They applied several models in calculating transfer coefficients in the 
chain soil.plants.food.human body. The soil-milk transfer coefficient ranges from less than 
1 to 20 Bq/L per kBq/m2. 
Table 13.3-8 presents concentrations of 137Cs in the pasture, milk and meat, and their daily 
uptake (Richards and Hance 1996 [157613]). These concentrations are used to calculate transfer 
coefficients using the following formula (CRWMS M&O 2000 [152435], Table 1) 
Transfer coefficient = Concentration in meat or milk / Intake 
For Chernobyl, the meat and milk transfer coefficients are 1.6-2.0  10-2 day/kg and 6.4-8.0  
10-3 day/L, respectively. For the Yucca Mountain Biosphere Process Model, the beef and milk 
transfer coefficients are 5  10-2 day/kg and 8  10-3 day/L, respectively (CRWMS M&O 2000 
[151615], Table 3-14). For the disruptive event Yucca Mountain scenario, the mean meat 
transfer coefficient is 2.4  10-2 day/kg (BSC 2003 [163958], p. 21, Table 4.1-1) and the mean 
milk transfer coefficient is 7.7  10-3 day/L (BSC 2003 [163958], p. 22, Table 4.1-1), which are 
practically the same as those from the Chernobyl data. 

13.3.8.3 Radionuclide Accumulation in Fish 
Smith et al. (2000 [156906]) measured 137Cs activity concentrations in terrestrial vegetation at 
seven sites, in lake water, and in mature fish in Cumbria, UK. They determined that 137Cs from 
the 1986 Chernobyl accident has persisted in freshwater fish for much longer than was initially 
expected because of the so-called fixation process of cesium in soil. They concluded that the 
effective ecological half-life in young fish, water, and terrestrial vegetation has increased from 
values of 14 years measured during the first five years after Chernobyl to 630 years 
determined since 1990. Jonsson et al. (1999 [156620]) measured cesium in nearly 4,000 fish, 
taking samples 24 times every year in a Scandinavian lake contaminated by Chernobyl fallout. 
The estimated half-life of cesium concentration in fish was 0.34.6 years. Jonsson et al. (1999 
[156620]) found that the decline in cesium was initially rapid for three to four years and then 
became much slower. About 10% of the initial peak radioactivity declined with a half-life of 8 
22 years. Smith et al. (2000 [157433]) determined the bioaccumulation factor of different fish in 
ten lakes of Belarus, Russia, and Ukraine from 1232 km from Chernobyl from 611 years after 
the accident. They determined that the bioaccumulation factor for 137Cs ranged from 8214,424 
L/kg for different lakes and types of fish (Smith et al. 2000 [157433], Table 2). The 137Cs 
bioaccumulation factor used in the Yucca Mountain Biosphere Process Model for freshwater fish 
is 2,000 L/kg (CRWMS M&O 2000 [151615], Table 3-15), which is within this range. The 
Yucca Mountain recommendation for the bounding value of the bioaccumulation factor is 15,000 
L/kg (CRWMS M&O 2000 [152435], Table 14), which agrees with the maximum value 
determined by Smith et al. (2000 [157433], Table 2). Smith et al. (2000 [157433], p. 360) used 
the term concentration factor, which is the same as the bioaccumulation factor for the Yucca 
Mountain Biosphere Process Model. 
13.3.8.4 Livestock Uptake 
Livestock uptake represents radionuclide transfer to animal food products. The 137Cs transfer 
coefficients to cattle, milk, and meat in the Ukraine from 19871993 are different for soils with 
different soil pH values (Bar'yakhtar 1997 [156953], Table I.5.4). In 1993, radionuclide 
concentration in beef from collective farms, where fodder was produced on arable soils, ranged 
from 2071 Bq/kg. At the same time, the radionuclide concentration in meat from private farms 
ranged from 75520 Bq/kg, and in wild animal meat, it ranged from 5041,540 Bq/kg 
(Bar'yakhtar 1997 [156953], pp. 370371). In the Rivne region of Ukraine, the transfer factor 
for beef ranged from 0.160.59 m2/kg for collective farms, and ranged from 11.7 m2/kg for 
private farms. The difference between the collective and private farms can be explained by the 
fact that countermeasures were undertaken on collective farms. 
Empirical data from the leaching and transfer coefficients summarized in Section 13.2.8 show 
that the initial dissolution of hot particles exposed to the atmosphere increases the concentration 
of radionuclides, which then decreases with time. The ecological half-life of radionuclides in 
soils, plants, and foodstuff is less than physical values for radionuclides. Diffusion and 
absorption processes are limiting factors for radionuclide transfer in soils. Radionuclide transfer 
to a plant depends on two main mechanisms: (1) direct deposition on the plant surfaces from 
resuspension of contaminated soil particles or from irrigation with contaminated water, and (2) 
the root uptake of radionuclides, which is limited by diffusion and convective transport from the 
soil to the root. 

13.3.9 Human Receptor Exposure 
This section defines the Chernobyl human receptors and critical groups, gives examples of 
human exposure pathways and BDCF calculations, and presents the radiation doses from 
plutonium. 
13.3.9.1 Chernobyl Human Receptors and Critical Groups 
For risk-assessment purposes, the critical group for Chernobyl was selected to be individuals 
who were born in the year of the accident and who will live in the same contaminated location 
for 70 years (IAEA 1991 [156750], p. 207). Exposure of the population was from two main 
pathways: (1) the radiation dose to the thyroid as a result of the concentration of radioiodine and 
similar radionuclides in the gland, and (2) the whole-body dose caused largely by external 
irradiation mainly from radiocesium (NEA 1995 [156632], p. 30). About 80% of the lifetime 
dose was accumulated in the first ten years after the accident (Los' and Poyarkov 2000 [157508], 
p. 194). A group of people that can be considered to include the reasonably maximally exposed 
individual includes pregnant women, fetuses, and school children (Lazjuk et al. 1995 [156626], 
p. 71). The risk of radiation for these people is correlated with the level of 137Cs contamination, 
because 137Cs is the most significant contributor to internal and external doses (see Section 
13.3.9.2). 
Doses received by the public are different for rural populations, including agricultural workers 
and come-backers living within the highly contaminated exclusion zone, and urban 
populations. Doses have varied with time since the Chernobyl accident. 
13.3.9.2 Human Exposure Pathways 
Exposure pathways to the populace resulting from the Chernobyl accident occurred through (1) 
external irradiation from radioactive materials deposited on the ground from the radionuclide 
fallout or accumulation from irrigation water, and (2) internal irradiation caused by inhalation of 
airborne materials and ingestion of contaminated foodstuff. Table 13.3-9 presents an example of 
the typical types of data for the city of Bragin, Belarus, and includes the following categories of 
data: 
Population (number of children and total inhabitants) 
Deposition density of 137Cs and 90Sr 
Exposure rate 
Concentration in foods 
Consumption rate of foods 
Internal dose. 
This table also illustrates changes in the radionuclide concentration with time in different types 
of foods and actual internal doses in different population groups. 
The dose received by the rural population makes up the bulk of the collective dose. Collective 
dose is the total dose over a population group exposed to a given source and is represented by the 
product of the average dose to the individuals in the group, multiplied by the number of persons 
comprising the groupfor example, person-sievert (Sv) (NEA 1995 [156632], p. 59). Between 

1986 and 1996, the rural population received 77% of the collective total effective dose. From 
1986 to 1996, the mean annual collective effective internal dose was 65% versus 35% for the 
external dose for the rural areas (Los and Poyarkov 2000 [157508], p. 186). In the urban areas, 
the main source of the internal dose was inhalation, while in the rural, agricultural areas, the 
internal dose consisted of both inhalation and ingestion of radionuclide particles. 
About 95% of the contribution to external and internal doses to the rural population was by 137Cs 
(Los and Poyarkov 2000 [157508], p. 185). Based on Chernobyl investigations, the dose 
received by the public from TRU elements would be several dozen to several hundred times 
smaller than that from strontium and cesium over the 70-year period following the accident. 
Table 13.3-10a shows that the effective dose for the rural population is higher than that for the 
urban population, because people in rural areas spent more time outdoors. The effective dose 
decreased rapidly for the first year after the accident and then slowly until 1996. Table 13.3-10a 
presents changes in the effective dose of external radiation from 137Cs with time. (The same 
temporal trend can be expected for Yucca MountainFigure 6.2-1 of BSC (2003 [163958])- 
indicates the decrease in the BDCF for 90Sr for about 10 years). These values were used to 
calculate the dose coefficients expressed in mrem/yr per pCi/m2, which are given in Table 13.3- 
10b. The 137Cs dose coefficient exposure from the ground surface for the Yucca Mountain 
Disruptive Event Scenario is 2.85  10-19 Sv/s per Bq/m2 (BSC 2003 [163958], Table 4.1-4), 
which corresponds to 2.43  10-5 (mrem/yr)/(pCi/m2). This value reasonably matches the 
Chernobyl dose calculated for the first year after the accident (see Table 3-10b). (The annual 
value of 1 Sv/(kBq/m2) corresponds to 3.7  10-6 mrem/yr per pCi/m2). 
Table 13.3-10c presents the BDCFs from the Yucca Mountain disruptive event scenario (BSC 
2003 [163958], Table 6.2-1), showing that the dose from inhalation of 137Cs is a small portion of 
the total dose, which corresponds to Chernobyl findings. Figure 13.3-12 shows that the 
calculated Yucca Mountain and observed Chernobyl BDCFs for 137Cs are within the same order 
of magnitude for both minimum and maximum values. (To relate BDCF values using the 
method presented above to potential contamination at Yucca Mountain, the BDCF units reported 
in Table 5-17 of CRWMS M&O (2000 [151615]) have to be converted from mrem/yr per pCi/L 
to mrem/yr per pCi/m2. Assuming that the wetted zone due to potential irrigation is 1 cm thick 
and the volumetric moisture content is 10%, 1 mrem/yr per pCi/L is equivalent to 1 mrem/yr per 
pCi/m2.) 
Table 13.3-11 shows maximum 137Cs concentrations (kBq/m2) in soils producing an internal 
radiation dose of 1 mSv/yr (100 mrem/year). The total radiation dose of 100 mrem/year is the 
annual permissible limit for the general public (DOE 1994 [104736], p. 2-6). The corresponding 
BDCFs for the internal radiation were calculated from the formula 
BDCF = Internal radiation dose / Radionuclide concentration activity of soil 
which is based on the BDCF definition given in CRWMS M&O (2000 [151615], Section 
3.1.4.1). Because the Yucca Mountain model uses BDCFs in mrem/year per pCi/m2, the 
concentrations in pCi/m2 (Columns 4 and 5 of Table 13.3-11) were first calculated using the 
conversion factors 1 kBq = 27,027 pCi, and then the corresponding BDCFs (Columns 6 and 7 of 
Table 13.3-11) were calculated from the formula 

BDCFs = 100 mrem/year / Concentration in soil (pCi/m2) 
Because Table 13.3-11 presents maximum 137Cs concentrations to obtain the annual dose of 1 
mSv (1 mSv = 100 mrem), BDCFs calculated are minimal. These can be compared to BDCFs 
derived for both disruptive and nondisruptive (groundwater) contamination event pathways at 
Yucca Mountain as shown in Figure 13.3-12. 
For Chernobyl loamy soils, which have properties closer to Yucca Mountain soils than other 
types of soils, the BDCF is 1.25  10-5 mrem/yr per pCi/m2 for tilled soils. This value is within 
the same order of magnitude as the minimal BDCFs for the Yucca Mountain disruptive 
contamination scenario. Note that contaminated groundwater is not taken into account when 
calculating BDCFs for the disruptive event scenario for Yucca Mountain (CRWMS M&O 2000 
[151615], Section 3.3.2), while the use of contaminated groundwater contributed to the internal 
dose obtained after the Chernobyl accident. (Contaminated groundwater for the Yucca Mountain 
biosphere is included in dose calculations performed in the TSPA model once the radionuclide 
concentrations are estimated.) 
The critical group pathway analyses and sensitivity studies conducted for Yucca Mountain 
showed that the BDCF values for most radionuclides were dominated by only two consumption 
rates: water and leafy vegetables (CRWMS M&O 2000 [151615], Section 3.1.2.3). In contrast, 
Chernobyl data showed that drinking groundwater was an insignificant contributor to the human 
dose (Bugai et al. 1996 [156596]). However, milk and milk products contributed significantly to 
the human dose (Table 13.3-12), more so than would be true for the Yucca Mountain critical 
population because the consumption of milk products in the Ukraine [the average is 0.181.5 
L/day in different regions (Bar'yakhtar 1997 [156953], Table I.3.9I.3.11)] is much higher than 
that in the United States. (The average used in the Yucca Mountain Biosphere Process Model is 
0.011 L/day (CRWMS M&O 2000 [151615], Table 3-16)). More importantly, the short-lived 
radionuclides associated with the Chernobyl accident are far more significant contributors to 
human dose. 
The IAEA (1991 [156750], Part E, pp. 222237) estimated external and internal doses based on 
(1) direct measurements and (2) dose calculations in settlements located within the area with 
137Cs concentrations exceeding 550 kBq/m2 (>15 Ci/km2). Figures 13.3-13a indicates that a 137Cs 
body concentration has a log-normal distribution across the population. Different dietary 
restrictions or habits (such as eating large quantities of forest mushrooms, an example relevant to 
Yucca Mountain in principle only) could cause variable body concentration distributions 
between different settlements. Figures 13.3-13b shows a significant scatter of data for the agedependent 
distribution of 137Cs. 
Commercial fishermen on the Kiev reservoir, who consumed 360 kg/yr of fish in 1986, received 
4.7  10-4 and 5  10-3 Sv from 90Sr and 137Cs, respectively (Berkovski et al. 1996 [156592], p. 
41), i.e., the dose ratio of cesium to strontium was 10.6. The predicted contributions to the 
collective effective dose resulting from irrigation, municipal tap water, and fish for members of 
the general public for over 70 years following the ChNPP accident are shown in Table 13.3-13. 
The predicted contribution of 90Sr to the collective dose resulting from the use of Dnieper water 
is 80% (Berkovski et al. 1996 [156592], p. 42). Figure 13.3-14 presents the contribution of 90Sr 

and 137Cs in different components of food-chain pathways to averaged effective internal dose for 
Kiev in 1993. The contribution of radionuclides through the drinking-water pathway is different 
in different areas. For example, the drinking-water pathway contribution for the people of Kiev 
was about 6% of the total radiation dose; for the people of the southern Ukraine, it was 14% to 
34% (Voitsekhovich et al. 1996 [156921], Figure 7). 
Bugai et al. (1996 [156596]) estimated health risks caused by radionuclide migration to 
groundwater and compared these risks with risks from exposure to radioactive contamination on 
the ground surface. They determined that the estimated health risk to hypothetical, selfsufficient 
residents in the 30 km exclusion zone is dominated by external and internal irradiation 
from 137Cs, caused mainly by ingestion of agricultural products. The estimated risk caused by 
drinking contaminated groundwater is approximately an order of magnitude lower. Strontium-90 
migration via groundwater to surface water used in downriver population centers shows that 
groundwater can potentially only marginally contribute to the offsite radiological risk. Bugai et 
al. (1996 [156596], pp. 1314) calculated the annual committed effective doses caused by 
consumption of 90Sr-contaminated water using an ingestion dose conversion factor of 3.9  10-5 
mSv/Bq, determined by the Eckerman et al. (1988 [101069], Section II) formula. Committed 
effective dose equivalent is the resulting dose committed to the whole body from radionuclides 
absorbed internally over a 50-year period (DOE 1994 [104736], p. 2-3). Berkovski et al. (1996 
[156592], p. 42) determined that consumption of drinking water in 1986 by the populace in the 
Kiev region led to the maximum individual annual committed effective doses of 1.7  10-5 and 
2.7  10-5 Sv from 90Sr and 137Cs, respectively. 
13.3.9.3 Radiation Doses from Plutonium 
The most hazardous particles are those containing plutonium, which can contribute significantly 
to radioactivity in dust. In the Yucca Mountain disruptive event scenario, the sum of fractions of 
plutonium isotopes could significantly contribute to the inhalation exposure pathway (CRWMS 
M&O 2003 [163958], Table 6.2-7) as was observed at Chernobyl. 
The main pathways for plutonium intake resulting from the Chernobyl accident are inhalation 
(which has been treated as an acute intake since 1986), uniform oral intake from food products, 
and inhalation of resuspended dust particles. Bondarenko et al. (2000 [156593], p. 475) 
calculated that the transfer factor of plutonium into grass is 0.3  10-3 (Bq/kg)/(Bq/m2), and it 
could be as low as 0.15  10-6 (Bq/kg)/(Bq/m2) due to the superficial contamination of grass. 
They also determined that the soil-diet transfer coefficient normalized to unit contamination 
density is 1.2  10-7 (Bq/kg)/(Bq/m2). In this calculation, Bondarenko et al. (2000 [156593], p. 
475), assumed that the soil-diet transfer coefficient is 2.4  10-5 (Bq/kg)/(Bq/m2); the soil 
density is 2 g/cm3; radioactivity is uniformly distributed within the top 10 cm soil profile; 
plutonium concentration in soils is 3,700 Bq/m2, which is typical for the southeastern periphery 
of the exclusion zone; initial fallout particles of 1 m in diameter, precipitating on inert soil 
particles, form agglomerates 5 m in diameter; rural inhabitants spend one-third of the day 
outdoors; and the averaged resuspension coefficient is 10-9/m. 
Bondarenko et al. (2000 [156593], pp. 476477) also presented data on the content of a-emitting 
isotopes of plutonium in the human skeleton. They found that the average plutonium content in 
25 samples was 4.9  10-2 Bq for regions contaminated at the level of 20 mCi/km2 (740 Bq/m2). 

Table 13.3-14 presents the calculated content of a-emitting plutonium isotopes in the human 
skeleton in 1998 and compares these data with global fallout. This table indicates that the 
Chernobyl data exceeded that resulting from global fallout by 2.59.2 times. 
13.4 SUMMARY AND CONCLUSIONS 
Section 13.3 reviewed information from the Chernobyl accident regarding the exposure 
pathways, distribution of radioactive contaminants in the biosphere, and inputs to risk assessment 
that may be relevant to future revisions of the Yucca Mountain Biosphere Process Model. 
Despite the difference in climatic conditions and the accident/potential-exposure scenarios for 
Chernobyl and Yucca Mountain, respectively, the Chernobyl data serve as a source of 
information to improve the confidence in a conceptual model of exposure pathways and process 
models. As part of the biosphere-model validation for both groundwater release and volcanic 
release scenarios, the YMP is interested in measurements that could represent input data in 
validating models for specific environmental processes, as listed in Section 13.2. The main 
conclusions that can be drawn from Chernobyl with respect to these processes and parameters 
are described below. 
Radionuclide transfer from soil to plants via atmospheric resuspension, including deposition of 
resuspended material on plant surfaces (see Section 13.3.5). Resuspension of radionuclides by 
wind-driven dust is an important factor after the tillage of agricultural lands, increasing the 
resuspension by more than an order of magnitude. Resuspended material is likely to settle on 
plant surfaces, thereby increasing their contamination. The Chernobyl data on hot-particle 
dispersal and dust transport showed that radionuclides attach to dust particles and move as 
combined particles. Aspects of models of atmospheric contaminant dispersal, radionuclide 
fallout, radionuclide resuspension, and particle-size distributions developed by Garger et al. 
(1999 [151483]), Goldman et al. (1987 [156820]), and Kashparov et al. (2000 [156622]) may be 
relevant to building confidence in a model for radionuclide resuspension resulting from a 
volcanic eruption through the Yucca Mountain repository. 
Radionuclide transfer from animal food to animal products (see Sections 13.3.8.2 and 13.3.8.4). 
These data could be used in assessing the Yucca Mountain models for meat and milk 
contamination. Environmental half-life periods of decay of 137Cs content in milk and agricultural 
products were shorter than those initially expected. 
Inhalation of resuspended contamination material originally deposited on the ground (see 
Sections 13.3.5 and 13.3.9.3). The most hazardous particles associated with the Chernobyl 
accident are those containing plutonium, which can contribute significantly to radioactivity in the 
dust. The inhalation doses for agricultural laborers are greater than the external doses, with the 
plutonium concentration exceeding the acceptable limit by an order of magnitude. 
Radionuclide accumulation in soils and plants under irrigation using contaminated water (see 
Section 13.3.7). Irrigation using contaminated water creates radioactive contamination of both 
irrigated soils and agricultural products (Perepelyatnikov et al. 1991 [156822]). The increase in 
the concentration of radionuclides in soils during irrigation in the southern Ukraine, where 
environmental conditions are more similar to those at Yucca Mountain than are those in the 

Chernobyl vicinity, confirms the concept of a radionuclide-buildup factor used in the Yucca 
Mountain Biosphere Process Model. 
In summary, results of the Chernobyl literature survey suggest that soil type influences the 
ecological half-life of radionuclides in the biosphere, both in regard to soil bioaccumulation 
factors and advective and diffusive transport properties that limit radionuclide transfer to plant 
roots. With respect to rural populations, agricultural methodsincluding irrigation and tillage 
and crop types play an important role in resuspension of radionuclides. Resuspended material is 
likely to increase the contamination of plant surfaces. Resuspended radionuclides would 
increase the inhalation dose for agricultural workers, which would be particularly significant for 
plutonium associated with the Chernobyl accident. 
Chernobyl data include both the relatively short-lived isotopes of iodine, cesium, and strontium, 
and long-lived transuranic elements such as plutonium and americium. Among the long-lived 
radionuclides of interest to Yucca Mountain, and not present at Chernobyl, are 129I, 227Ac, 232U, 
233U, 237Np, 243Am, 210Pb, 231Pa, 226Ra, 230Th, and 242Pu (CRWMS M&O 2000 [151615], Sections 
3.3.1 and 3.3.2). 
Numerous data collected for the past 15 years about the distribution and accumulation of 
radioactive materials in different parts of the biosphere after the Chernobyl accident, including 
the main exposure pathways and mechanisms of radioactive contamination of the environment 
and the population, can be used to build confidence in Yucca Mountain conceptual and 
numerical models. They can also be used to enhance models for long-term transport processes 
and radiation doses associated with possible exposure to radioactive material in the vicinity of 
the potential nuclear waste disposal site at Yucca Mountain. For the potential groundwatercontamination 
scenario at Yucca Mountain, radionuclide-contaminated water, which is to be 
used as the source of drinking water, irrigation, animal watering, and domestic uses, is expected 
to increase the likelihood of ingestion uptake of radionuclides by humans. Chernobyl data on the 
atmospheric distribution of contaminants, their fallout, and redistribution in soils and plants may 
be considered an anthropogenic analogue for the potential release of radionuclides caused by a 
volcanic eruption at Yucca Mountain, accompanied by atmospheric dispersal of contaminants 
into the environment through ash fallout on the land surface. Analogues related to volcanic 
processes are discussed in Section 14. 

Table 13.3-1. Vertical Distribution of Plutonium and Uranium in Soils in the Vicinity of the ChNPP 
Depth (cm) 
239(240)Pu (%) 
Ratio 238U/235U 
0-1 
91-97 
79.9-103.5 
1-2 
2.9-7.9 
126.7-135.8 
2-3 
0.3-0.6 
129.6-137.3 
3-4 
0-0.2 
137.1-137.8 
4-5 
0-0.1 
137.6-137.8 
Source: Sobotovich 1992 [134218], Table 3.6. 
Table 13.3-2. Typical Radioactive Contamination Levels (Bq/L) 
for Groundwater in the Inner Exclusion Zone 
Source of water 
90Sr 
137Cs 
239+240Pu 
241Am 
MPC (maximum permissible 
concentration) 
14.8 
555.5 
81.5 
70.3 
Regional groundwater 
contamination 
0.1-10 
0.1-1 
=0.01 
=0.01 
Shelter 
10-103 
0-100 
-- 
-- 
Interim radioactive waste 
storage sites 
102-104 
0.1-10 
=0.01-1 
=0.01 
Cooling pond 
1-102 
0.1-1 
-- 
-- 
Artesian aquifer in Eocene 
deposits 
=0.01 
=0.01 
-- 
-- 
Source: Shestopalov and Poyarkov 2000 [157507], Table 5.4.1. 
Table 13.3-3. Percentages of Measured Concentrations of Radionuclides 
in Kiev Metropolitan Area Groundwater, 19921996 
137Cs Concentration, mBq/L 
90Sr Concentration, mBq/L 
Aquifer 
<10 
1050 
51150 
>150 
<10 
1050 
>50 
Quaternary 
24% 
56% 
14% 
6% 
53% 
40% 
7% 
Eocene 
45% 
41% 
9% 
5% 
71% 
21% 
8% 
Late Cretaceous 
(Cenomanian) 
Early Jurassic 
(Callovian) 
46% 
31% 
13% 
10% 
80% 
20% 
-- 
Middle Jurassic 
(Bajocian) 
47% 
28% 
15% 
10% 
62% 
35% 
3% 
Source: Shestopalov and Poyarkov 2000 [157507], p. 150, Table 5.4.2. 
NOTE: The depths tested are: Quaternary aquifer: 218 m; Eocene aquifer: 4565 m; Late 
Cretaceous (Cenomanian)Early Jurassic (Callovian) aquifer: 80150 m; Middle 
Jurassic (Bajocian) aquifer: 200300 m. 

Table 13.3-4. Cesium-137 Concentrations in Agricultural Products Grown on Lands Irrigated Using Water 
from the Dnieper River Reservoirs, Compared with Lands Irrigated by Water from Other Sources 
Irrigation using Contaminated Water from Dnieper River 
Reservoirs (see Figure 13.3-8) 
Irrigation Using 
Uncontaminated Water 
Type of Plant 
Year 
Kanev 
Kremenchuh 
Dneprodzerzhinsk 
Kakhovka 
Kharkov 
Region 
Donetsk 
Region 
Winter wheat 
(seeds) 
1987 
1988 
50 
30 
50 
40 
25 
10 
30 
30 
8 
10 
10 
10 
Corn (seeds) 
1987 
1988 
10 
10 
10 
5 
5 
6 
6 
3 
2 
1 
2 
2 
Alfalfa 
1987 
1988 
600 
400 
600 
400 
370 
300 
320 
200 
80 
90 
100 
90 
Cabbage 
1987 
1988 
6 
6 
7 
4 
3 
2 
3 
3 
1 
1 
1 
1 
Tomato 
1987 
1988 
20 
20 
20 
10 
10 
10 
10 
20 
4 
6 
5 
5 
Tomato 
(vegetative 
mass) 
1987 
1988 
700 
400 
800 
500 
500 
200 
400 
200 
160 
200 
250 
200 
Cucumber 
1987 
1988 
40 
30 
40 
40 
20 
20 
20 
10 
10 
10 
10 
20 
Cucumber 
(vegetative 
mass) 
1987 
1988 
1,200 
800 
1,600 
1,100 
800 
400 
600 
300 
350 
300 
300 
200 
Source: Perepelyatnikov et al. 1991 [156822], p. 111, Table 5. 
NOTE: 137Cs reported as pCi/kg of air-dry mass 

Table 13.3-5. Distribution of (a) 137Cs and (b) 90Sr in the Soil Profile beneath 
Rice Paddies in 1988 after Three Years of Irrigation, Southern Ukraine 
a) 137Cs (in pCi/kg of air-dry soil) 
Year 
Type of Agriculture 
Soil layer (cm) 
1986 
1987 
1988 
Bare 
Bare 
Bare 
Rice 
Alfalfa 
Fallow 
Fallow 
Rice 
Alfalfa 
Alfalfa 
Fallow 
Rice 
Rice 
Fallow 
Rice 
Rice 
Rice 
Rice 
00.5 
0.45 
0.41 
0.52 
0.6 
0.62 
0.71 
0.52 0.43 0.39 0.39 0.51 0.5 0.49 
24 0.4 0.4 0.37 0.41 0.38 0.37 
46 0.38 0.36 0.4 0.38 0.42 0.41 
68 0.43 0.45 0.42 0.37 0.39 0.42 
810 0.37 0.37 0.38 0.38 0.37 0.32 
1020 0.19 0.4 0.39 0.41 0.4 0.41 
Average in a 
layer 020 cm 
0.37 0.4 0.42 0.44 0.45 0.48 
Contamination 
(Ci/km2) 
0.43 
0.39 
0.39 
0.51 
0.5 
0.49 
24 0.4 0.4 0.37 0.41 0.38 0.37 
46 0.38 0.36 0.4 0.38 0.42 0.41 
68 0.43 0.45 0.42 0.37 0.39 0.42 
810 0.37 0.37 0.38 0.38 0.37 0.32 
1020 0.19 0.4 0.39 0.41 0.4 0.41 
Average in a 
layer 020 cm 
0.37 0.4 0.42 0.44 0.45 0.48 
Contamination 
(Ci/km2) 
0.4 
0.4 
0.37 
0.41 
0.38 
0.37 
46 0.38 0.36 0.4 0.38 0.42 0.41 
68 0.43 0.45 0.42 0.37 0.39 0.42 
810 0.37 0.37 0.38 0.38 0.37 0.32 
1020 0.19 0.4 0.39 0.41 0.4 0.41 
Average in a 
layer 020 cm 
0.37 0.4 0.42 0.44 0.45 0.48 
Contamination 
(Ci/km2) 
0.38 
0.36 
0.4 
0.38 
0.42 
0.41 
68 0.43 0.45 0.42 0.37 0.39 0.42 
810 0.37 0.37 0.38 0.38 0.37 0.32 
1020 0.19 0.4 0.39 0.41 0.4 0.41 
Average in a 
layer 020 cm 
0.37 0.4 0.42 0.44 0.45 0.48 
Contamination 
(Ci/km2) 
0.43 
0.45 
0.42 
0.37 
0.39 
0.42 
810 0.37 0.37 0.38 0.38 0.37 0.32 
1020 0.19 0.4 0.39 0.41 0.4 0.41 
Average in a 
layer 020 cm 
0.37 0.4 0.42 0.44 0.45 0.48 
Contamination 
(Ci/km2) 
0.37 
0.37 
0.38 
0.38 
0.37 
0.32 
1020 0.19 0.4 0.39 0.41 0.4 0.41 
Average in a 
layer 020 cm 
0.37 0.4 0.42 0.44 0.45 0.48 
Contamination 
(Ci/km2) 
0.19 
0.4 
0.39 
0.41 
0.4 
0.41 
Average in a 
layer 020 cm 
0.37 0.4 0.42 0.44 0.45 0.48 
Contamination 
(Ci/km2) 
0.37 
0.4 
0.42 
0.44 
0.45 
0.48 
Contamination 
(Ci/km2) 
0.11 
0.12 
0.12 
0.13 
0.14 
0.14 
b) 90Sr (in pCi/kg of air-dry soil) 
Year 
Type of Agriculture 
Soil Layer (cm) 
1986 
1987 
1988 
Bare 
Bare 
Bare 
Rice 
Alfalfa 
Fallow 
Fallow 
Rice 
Alfalfa 
Alfalfa 
Fallow 
Rice 
Rice 
Fallow 
Rice 
Rice 
Rice 
Rice 
00.5 
70 
-- 
-- 
-- 
110 
120 
0.52 65 -- -- -- 110 110 
24 60 -- -- -- 100 122 
420 58 -- -- -- 100 115 
Average in a 
layer 020 cm 
60 -- -- -- 102 116 
Contamination 
(Ci/km2) 
65 
-- 
-- 
-- 
110 
110 
24 60 -- -- -- 100 122 
420 58 -- -- -- 100 115 
Average in a 
layer 020 cm 
60 -- -- -- 102 116 
Contamination 
(Ci/km2) 
60 
-- 
-- 
-- 
100 
122 
420 58 -- -- -- 100 115 
Average in a 
layer 020 cm 
60 -- -- -- 102 116 
Contamination 
(Ci/km2) 
58 
-- 
-- 
-- 
100 
115 
Average in a 
layer 020 cm 
60 -- -- -- 102 116 
Contamination 
(Ci/km2) 
60 
-- 
-- 
-- 
102 
116 
Contamination 
(Ci/km2) 
0.018 
-- 
-- 
-- 
0.031 
0.035 
Source: Perepelyatnikov et al. 1991 [156822], pp. 109110, Tables 2 and 3. 

Table 13.3-6. Estimated Soil-to-Plant Transfer Factors for Yucca Mountain Compared 
with Those Determined from Observations After the Chernobyl Accident 
Soil-to-Plant Transfer Factors (Dimensionless) 
Yucca Mountain 
Radionuclide 
Leafy 
Root 
Fruit 
Grain 
Chernobyl data Chernobyl data 
Strontium 
2.0E+00 
1.2E+00 
2.0E-01 
2.0E-01 
2.0E-021.2E+01 
Yttrium 
1.5E-02 
6.0E-03 
6.0E-03 
6.0E-03 
(3-70) x E-03 
Cesium 
1.3E-01 
4.9E-02 
2.2E-01 
2.6E-02 
2.0E-021.1E+00 
Radium 
8.0E-02 
1.3E-02 
6.1E-03 
1.2E-03 
(1-40) x E-03 
Thorium 
4.0E-03 
3.0E-04 
2.1E-04 
3.4E-05 
(1-700) x E-03 
Uranium 
8.5E-03 
1.4E-02 
4.0E-03 
1.3E-03 
1.6E-031.0E-01* 
Neptunium 
3.7E-02 
1.7E-02 
1.7E-02 
2.7E-03 
nE-02nE-01** 
Plutonium 
3.9E-04 
2.0E-04 
1.9E-04 
2.6E-05 
nE-081.0E+00 
Americium 
2.0E-03 
4.7E-04 
4.1E-04 
9.0E-05 
nE-061.0E-01 
Source: Bar'yakhtar 1997 [156953], p. 271 for Chernobyl; CRWMS M&O 2000 [151615], Table 3-10 for 
Yucca Mountain. 
NOTE: * Data are for 238U; **n = any number from 1 to 10. 
Table 13.3-7. Soil-to-Fodder Transfer Coefficients Determined after the Chernobyl Accident for 137Cs 
Soil Type and pH 
Crop 
Derno-podsol 
pH=4.5-5.5 
Gray Forest 
pH=5.6-6.5 
Chernozem 
pH=6.6-7.2 
Hay from natural grass 
10 
4 
1.8 
Hay from planted grasses 
4 
3 
1.6 
Vetch 
2.7 
0.45 
0.2 
Clover 
1.8 
0.3 
0.3 
Lupine 
1.5 
0.4 
0.15 
Alfalfa 
0.8 
0.4 
0.2 
Silage 
0.4 
0.2 
0.08 
Fodder beet 
0.5 
0.35 
0.2 
Potato 
0.25 
0.13 
0.045 
Winter grain 
0.5 
0.2 
0.05 
Rye 
0.4 
0.1 
0.04 
Barley 
0.3 
0.1 
0.06 
Source: Shestopalov and Poyarkov 2000 [157507], p. 174, Table 5.6.2 
NOTE: 137Cs reported as (Bq/kg) / (kBq/m2) (mean for 19871990). 

Table 13.3-8. Concentrations of 137Cs in Pasture, Meat and Milk, and Calculated Transfer Coefficients 
Transfer coefficients 
Pasture 
Contamination 
(Bq/kg) 
Intake* 
(kBq/day) 
Meat 
(Bq/kg) 
Milk 
(Bq/kg) 
Meat 
(day/kg) 
Milk 
(day/L) 
250 
17.5 
280 
112 
1.6E-02 
6.4E-03 
500 
36 
700 
280 
1.9E-02 
7.8E-03 
1,000 
70 
1,400 
550 
2.0E-02 
7.9E-03 
1,500 
105 
2,100 
840 
2.0E-02 
8.0E-03 
2,000 
140 
2,800 
1,120 
2.0E-02 
8.0E-03 
3,000 
210 
4,200 
1,680 
2.0E-02 
8.0E-03 
5,000 
350 
7,000 
2,800 
2.0E-02 
8.0E-03 
10,000 
700 
14,000 
5,600 
2.0E-02 
8.0E-03 
Source: Richards and Hance 1996 [157613]. Only equilibrium concentrations are included in the 
table. 
NOTE: *Assumes daily intake of 70 kg fresh herbage/animal. For comparison, in the 
Yucca Mountain biosphere model, the dairy and beef cow feed consumption 
rates are 55 and 68 kg/day, respectively (CRWMS M&O [151615], Table 3-13). 

Table 13.3-9. Example of the Database to Assess Radiation Dose for the City of Bragin, Belarus 
Population 
Population Group 
1986 
1987 
1988 
1989 
1990 
Children 
1,667 
-- 
-- 
2,065 
-- 
Total inhabitants 
5,600 
4,900 
-- 
5,888 
-- 
Deposition Density (kBq/m2) 
Radionuclide 
1986 
1987 
1988 
1989 
1990 
Cesium-137 
1,700 
1,000 
270 (51,000) 1) 
(n = 8) 2) 
1,000 (n = 18) 
830 (n = 50) 
-- 
Strontium-90 
-- 
-- 
-- 
78 (n = 9) 
-- 
Exposure Rate (R/h) 
1986 
1987 
1988 
1989 
1990 
Measurement 
8,000 (10 May) 
680 (10 May) 
-- 
-- 
-- 
Concentration in Foods (Bq/kg) (approximate median values) 
(Data from Institute of Agricultural Radiology, Gomel) 
1986 
1987 
1988 
1989 
1990 
Milk 
1,600 
1,500 
220 
300 
260 
Root vegetables 
740 
630 
330 
370 
370 
Green vegetables 
3,700 
740 
370 
300 
220 
Vegetables/fruit 
1,100 
590 
300 
220 
330 
Berries, mushrooms 
2,200 
1,100 
1,300 
2,600 
1,100 
Honey 
1,300 
1,900 
1,500 
300 
300 
Eggs 
1,300 
190 
190 
190 
300 
Meat 
1,700 
1,100 
740 
260 
300 
Fish 
-- 
1,800 
740 
1,500 
220 
Consumption Rate (g/day) 
Food Item 
Rural settlement 
All Belarus 
Milk 
735 
690710 
Bread, white 
220 
240 
Bread, dark 
350 
350 
Potatoes 
540 
680 
Vegetables 
190 
240 
Fruit, berries 
160 
150 
Berries 
-- 
1.5 
Mushrooms 
6 
7 
Meat 
150 
180 
Fish 
46 
60 
Internal Dose (mSv) 
(Data for 1986, 1987: Institute of Biophysics, Moscow; data for 
1988, 1989: Institute of Radiation Medicine, Minsk) 
134 + 137Cs 
1986 
1987 
1988 
1989 
1990 
Average Children 
Teenagers 
Adults 
2 (n = 292) 
5 (n = 87) 
4 (n = 683) 
1 (n = 94) 
3 (n = 131) 
3 (n = 111) 
0.2 (n = 203) 
0.2 (n = 731) 
0.3 (n = 641) 
0.1 (n = 3) 
0.1 (n = 3) 
0.2 (n = 131) 
-- 
-- 
-- 
Maximum Children 
Teenagers 
Adults 
15 
22 
12 
7 
17 
8 
-- 
-- 
-- 
-- 
-- 
-- 
-- 
-- 
-- 
90th percentile Children 
Teenagers 
Adults 
10 
13 
8 
575 
-- 
-- 
-- 
-- 
-- 
-- 
-- 
-- 
-- 
Source: IAEA 1991 [156750], Part E, Table 2-1. 
NOTE: 1) Range 
2) Number of measurements 

Table 13.3-10a. Dynamics of the Effective Dose of External Radiation 
to Ukrainians from 137Cs Contamination after the Chernobyl Accident 
Year 
Population 
group 
1986* 
1987 
1988 
1989 
1990 
1991 
1992 
1993 
1994 
1995 
1996 
Urban 
6.0 
1.5 
1.4 
1.4 
1.3 
1.3 
1.2 
1.2 
1.1 
1.0 
1.0 
Rural 
14.3 
3.5 
3.4 
3.3 
3.2 
3.1 
3.0 
2.7 
2.5 
2.4 
2.2 
Source: Los' and Poyarkov 2000 [157508], Table 6.2.1, p. 187. 
NOTE:* 1986 data were estimated after the accident. 137Cs reported for 19861996, Sv/(kBq/m2) 
Table 13.3-10b. Calculated BDCFs for 137Cs after the Chernobyl Accident 
Year 
Population 
group 
1986 
1987 
1988 
1989 
1990 
1991 
1992 
1993 
1994 
1995 
1996 
Urban 
2.2E-05 
5.6E-06 
5.2E-06 
5.2E-06 
4.8E-06 
4.8E-06 
4.4E-06 
4.4E-06 
4.1E-06 
3.7E-06 
3.7E-06 
Rural 
5.3E-05 
1.3E-05 
1.3E-05 
1.2E-05 
1.2E-05 
1.1E-05 
1.1E-05 
1.0E-05 
9.3E-06 
8.9E-06 
8.1E-06 
NOTE: See Section 13.3.9.2. Units in mrem/yr per pCi/m2 
Source: Table 13.3-10a. 
Table 13.3-10c. Yucca Mountain BDCFs for 137Cs for the Disruptive Event Scenario for the 
Transition Phase, 1 cm and 15 cm Ash Layers and Annual Average Mass Loading 
1cm ash layer 
15cm ash layer 
BDCFs 
mrem/yr 
per pCi/m2 
mrem/yr 
per pCi/m2 
Mean 
1.86E-06 
5.81E-06 
Min 
1.01E-06 
4.33E-06 
Max 
2.79E-05 
3.17E-05 
Source: Modified from CRWMS M&O 2001 [152536], Tables 11 and 13. 

Table 13.3-11. Maximum 137Cs Concentrations in Soils Producing 
Internal Dose of 1 mSv/yr and Calculated BDCFs 
1 
2 
3 
4 
5 
6 
7 
Concentration 
kBq/m2 
Concentration 
pCi/m2 
BDCF 
mrem/yr per pCi/m2 
Soil Type 
Meadow 
Tilled 
Meadow 
Tilled 
Meadow 
Tilled 
Peat-bog 
22 
93 
594,594 
2,513,511 
1.68E-04 
3.98E-05 
Sandy podzolic 
74 
130 
1,999,998 
3,513,510 
5.00E-05 
2.85E-05 
Light-gray 
podzolic 
148 
185 
3,999,996 
4,999,995 
2.50E-05 
2.00E-05 
Loamy 
chernozem 
222 
295 
5,999,994 
7,972,965 
1.67E-05 
1.25E-05 
Source: Shestopalov and Poyarkov 2000 [157507], Table 5.6.4. 
Table 13.3-12. Comparison of the Pathway Contribution (%) of Radionuclides 
Determined from Observations after the Chernobyl Accident in 1993 
90Sr 
137Cs 
Meat 
Leafy 
vegetables 
Milk and 
milk 
products 
Meat 
Leafy 
vegetables 
Milk and 
milk 
products 
Yucca Mountain 
5 (10) 
34 (42) 
0 (2) 
12 (4) 
16 (3) 
2 (0) 
Chernobyl 
4 
19 
54 
8 
2 
74 
Source: Yucca MountainCRWMS M&O 2000 [151615], Table 3-21; CRWMS M&O 2000 [151615], Table 
3-24 (in parentheses) 
Chernobyl Berkovski et al. 1996 [156592], p. 41. 

Table 13.3-13. Relative Contributions to the Collective Effective Dose 
from 137Cs and 90Sr, Resulting from the Chernobyl Accident 
Region/Source (%) 
Irrigation 
Municipal Tap 
Water 
Fish 
Kiev Region 
18 
43 
39 
Poltava Region 
8 
25 
67 
Crimean Republic * 
50 
50 
0 
Source: Berkovski et al. 1996 [156592], p. 42. 
NOTE: * No Dnieper River fish consumed in Crimean Republic 
Table 13.3-14. Calculated Content (Bq) of a-emitting Pu Isotopes in the Human Skeleton 
in 1998for the Ukraine-Belarus Territory with Contamination Density of 20 mCi/km2 
(740 Bq/m2)and Comparison of These Data with Global Fallout 
Type of Intake 
From Global Fallout 
From Chernobyl 
Fallout 
Primary inhalation 
1.310-3 
1.210-2 
Peroral due to superficial 
contamination 
1.610-3 
0.5610-2 
Peroral, biologically accessible forms 
3.210-5 
1.110-4 
Inhalation due to resuspension 
1.4210-6 
3.610-6 
Total 
2.910-3 
1.810-2 
Source: Bondarenko et al. 2000 [156593], Table 2. 

Source: CRWMS M&O 2000 [151615], Figure 3-1. 
Figure 13.2-1. Illustration of the Biosphere in Relationship to the Repository System 

Source: Modified from Shestopalov 1996 [107844], p. 1. 
Figure 13.3-1. Location of the ChNPP in (a) Europe, (b) Ukraine, and (c) the Kiev Region 

Source: Baryakhtar et al. 2000 [157504], Figure 2.5.2). 
NOTE: Dashed lines indicate country boundaries, and Dates/Times 
indicate date and time (in hours) in 1986. 
Figure 13.3-2. Fallout Trajectories of the ChNPP Accident 
Source: Bar'yakhtar 1997 [156953], Figure I.3.19, p. 263. 
Figure 13.3-3. Schematic Illustrating the Principal Pathways for the Radionuclides 
Entering the Biosphere through Terrestrial and Aquatic Ecosystems That Were 
Considered in Evaluating the Consequences of the Chernobyl Accident 

a) 
b) 
Source: Data of the Ukrainian Institute of Agricultural Radioecology (Kashparov et al. 
2001 [157400], Figure 3, Figure 2). 
NOTE: Concentrations are kBq/m2. 
Figure 13.3-4. Maps of the Terrestrial Contamination of the 30-km 
Chernobyl Exclusion Zone in Ukraine: (a) 90Sr; (b) 137Cs 

Source: Mboulou et al. 1998 [156628], Figure 1. 
Figure 13.3-5. Vertical Distribution of Actinides in Soil to 4.5 cm 

Source: Ivanov 2001 [156818], p. 57. 
NOTE: 1 - total content, 2 - radionuclides in fuel particles, 3 - mobile forms, and 4 - 
absorbed forms. 
Figure 13.3-6. Dynamics of Redistribution of 90Sr (a), 137Cs (b), and 239Pu (c) 
as a Function of Depth and Time in Derno-podzolic Silt Soils 

Source: Bar'yakhtar et al. 2000 [157505], Figure 3.5.2. 
NOTE: For Pasquill weather Category C with no wind and speed of 4.2 m/s at 100 m 
altitude, which corresponds to a wind speed of 2.53 m/s at the surface. 
Figure 13.3-7. Predicted Inhalation Doses as a Function of the Distance from the Hypothetical Collapsed 
Shelter 

Source: Modified from Bar'yakhtar 1997 [156953], Figure I.3.16, p. 250. 
NOTE: 1: mouth of Pripyat; 2: Kiev Reservoir; 3: Kanev Reservoir; 4: Kremenchug Reservoir; 5: Dneprodzerzhinsk 
Reservoir; 6: Zaporozh'e Reservoir 7: Kakhovka Reservoir. 
Figure 13.3-8. Concentration of 90Sr and 137Cs in Water from Seven Sites along the Dnieper River 

a) 
b) 
c) 
Source: Rosner and Winkler 2001 [156629], Figure 1. 
NOTE: All values are corrected for radioactive decay to 1 May 1986. Values for 1986 relate to the second half of the 
year only, i.e., the Chernobyl deposition phase is not included. The air-dust concentration (g/m3) is shown 
for comparison. 
Figure 13.3-9. Mean Values of (a) Radionuclide Concentrations in Air (Bq/m3), (b) Specific Activities in 
Air Dust (Bq/g), and (c) Radionuclide Ratios in Air (Bq/Bq) at Munich-Neuherberg Since 1985. 

Source: Bar'yakhtar et al. 2000 [157504], Figure 2-5.9. 
NOTE: Data points are experimental values; the line is the theoretical curve for pH=6. 
Figure 13.3-10. Effective Meadow-Vegetation Transfer Coefficients for 90Sr (Tf), 
Neglecting Redistribution in the Root Layer 
Bq/kg per kBq/m2 
Years after the accident 
Source: Ivanov 2001 [156818], p. 63, Figure 10 (summarized the results of several authors). 
NOTE: 1, 2: derno-podzolic sandy soils; 3: derno-podzolic silty and sandy soils; 4: mineral soils with fuel traces; 5: 
derno-podzolic sandy soils with fuel traces; 6: loamy and clayey soils. 
Figure 13.3-11. Dynamics of the Soil-Plant Transfer Coefficient for 137Cs, Which Is 
Approximated by a Function y = a exp(-bt) + (1-a) exp(-ct), for Meadow Grass Areas 

Source: CRWMS M&O 2000, [151615], Table 3-17 (for Yucca Mountain Groundwater 
Contamination Scenario). BSC 2003 [163958], Table 6.2-1 (for Yucca 
Mountain Disruptive Event Contamination Scenario). 
NOTE: For groundwater BDCF, refer to Section 13.3.9.2. 
Chernobyl External Dose (Table 13.3-10b); Yucca Mountain (YM) 
Disruptive Event Contamination Scenario (Table 13.3-10c); and Internal 
Radiation for Soil Types for Chernobyl (Table 13.3-11). 
Figure 13.3-12. Comparison of Minimum and Maximum Values of 137Cs BDCFs for Chernobyl (Ch) and 
Yucca Mountain 

b) 
a) 
Source: (a) IAEA (International Atomic Energy Agency) 1991 [156750], p. 265; 
(b) IAEA 1991 [156750], p. 263. 
Figure 13.3-13. (a) Frequency Distributions of the Logarithm of 137Cs Concentration in the Body at Two 
Selected Settlements (Bragin, Belarus, and Novozybkov, Russia); (b) Scatter Diagram of 137Cs 
Concentration in the Body as a Function of Age 
Source: Voitsekhovitch et al. 1996 [156921], Figure 8. 
Figure 13.3-14. Contribution of 90Sr and 137Cs in Different Components of Food Chain Pathways to 
Averaged Effective Internal Dose for the Population of the City of Kiev (1993 scenario) 

14. ANALOGUES FOR DISRUPTIVE EVENT SCENARIOS 
14.1 INTRODUCTION 
This section addresses disruptive event scenarios and the ways analogues have been used to 
define realistic scenarios, to bound parameters in models, and to build confidence that the right 
processes are included in models and represented by appropriate bounding conditions. 
Specifically, this section addresses the disruptive event categories for volcanism and seismicity, 
which are considered in total system performance assessment (TSPA). The scenario for nuclear 
criticality has been screened out from further consideration in the TSPA (DOE 2001 [153849], 
Section 4.3.3). However, aspects of criticality pertinent to the discussion on waste form 
degradation are presented in Section 4. The screened-in human-intrusion disruptive event 
scenario (e.g., drillhole penetrating a waste package) is not conducive to evaluation using natural 
analogues. Information found in Section 14.3 may help to support arguments associated with 
Key Technical Issues (KTI) KIA0204 listed in Table 1-1. 
14.2 BACKGROUND 
14.2.1 Volcanism 
The Yucca Mountain stratigraphy is composed of ashfall and ash flow tuffs that were deposited 
approximately 13 million years ago (Ma) as a result of eruption of the Timber Mountain caldera. 
This large-volume, explosive, silicic volcanism ended about 7.5 Ma. Basaltic volcanism began 
during the latter part of the caldera-forming phase and continued into the Quaternary (the last 2 
m.y.). Approximately 99% of the southwestern Nevada volcanic field, of which Yucca Mountain 
is a part, erupted between 15 and 7.5 Ma, with only 0.1% occurring during the basaltic phase of 
the last 7.5 m.y. In the Yucca Mountain region there are more than 30 basaltic volcanoes that 
formed between 9 Ma and 80,000 Ma. These volcanoes can be temporally and spatially separated 
into two distinct periods of volcanism, with the location of eruption of the younger, post-5 Ma 
volcanism shifted to the southwest (DOE 2001 [153849], Section 4.3.2.1.3). 
To assess the probability of volcanic activity disrupting a repository, a panel of experts was 
assembled to conduct a volcanic hazard assessment (CRWMS M&O 1996 [100116]). The hazard 
analysis models are based on data from Yucca Mountain studies, along with observations from 
analogue studies of modern and ancient volcanic eruptions. The results of the hazard analysis 
estimate that 1.7  10-8 igneous events per year could be expected to disrupt the repository (BSC 
2003 [163769], Table 22). This is the probability of a future basaltic dike intersecting the 
subsurface area of the repository. Furthermore, if a dike does intersect the repository, there is a 
77% chance that one or more volcanoes would form along the dike within the repository 
footprint, with magma erupting through the repository. Both the intrusive and volcanic eruptive 
scenarios are considered in performance assessment (PA) because of the potential consequences 
of radionuclide release that could affect the critical group. The role of analogues in assessing the 
eruptive style of potential future volcanoes and their expected consequences is addressed in 
Section 14.3. 

14.2.2 Seismicity 
Yucca Mountain is located in the Basin and Range tectonic province where earthquakes occur 
with some frequency. Geologic features of the site provide information on the regions past 
seismic activity, which is important in estimating the characteristics of future earthquakes. Based 
on these studies, the Yucca Mountain region has been rated as having low to moderate seismicity 
(CRWMS M&O 2000 [142321], Section 6.3.1). Seismic hazards are important to quantify as 
they could potentially affect the performance of a repository at Yucca Mountain. The seismic 
hazard at the site was assessed by a probabilistic seismic hazard analysis which produced results 
that allow assessment of the potential for ground shaking and fault rupture related to earthquakes 
(CRWMS M&O 1998 [103731]). 
Extensive design experience gained through operating critical facilities, such as nuclear power 
plants, will be relied upon to ensure performance of the repository and its supporting facilities 
during and after an earthquake. During the postclosure period, the risks related to seismic activity 
will decrease because the waste will be deep underground where seismic waves are more 
attenuated. A surface seismometer and another seismometer at 245-m depth in the Exploratory 
Studies Facility (ESF) measured seismic waves from a 4.7 magnitude earthquake at Frenchman 
Flat, about 45 km (28 mi) east of Yucca Mountain (DOE 2001 [153849], Section 4.3.2.2). 
Recordings from this earthquake, shown in Figure 14-1, clearly indicate the decrease in 
amplitude of ground motions deep within the mountain. However, a strong earthquake could 
cause rockfalls in the emplacement drifts or alter the pathways followed by groundwater. 
Investigations of these potential consequences have concluded that it is highly unlikely that the 
consequences would be significant to repository performance (DOE 2001 [153849], Section 
4.3.2.2). The role of analogues in building confidence in this conclusion is addressed in Section 
14.4. 
14.3 USE OF ANALOGUES IN VOLCANISM INVESTIGATIONS 
Reasoning by analogy was used to debate the conceptual model for the probability of an igneous 
dike or dike system reaching the near surface without any portion of the system erupting. This is 
an important issue for volcanic hazard assessment of a repository at Yucca Mountain. The San 
Rafael volcanic field has been used as an analogue to argue that the probability of a separate 
intrusive event that does not erupt is 2 to 5 times higher than the probability of an eruptive event 
(NRC 1999 [151592]). However, the scientific analysis report Characterize Framework for 
Igneous Activity at Yucca Mountain, Nevada (BSC 2003 [163769], Section 6.3.2.1) uses the 
Paiute Ridge igneous complex at the northeastern edge of the Nevada Test Site as an appropriate 
analogue to argue for a significantly lower rate for intrusions that do not result in eruption. Field 
observations at Paiute Ridge show that while some portions of individual dikes stagnated within 
approximately 100 m of the surface, other portions of the same dike did erupt. During the time 
period considered most significant by the panel of experts assembled for evaluating the volcanic 
hazard (the past 5 m.y., CRWMS M&O 1996 [100116], Figure 3-62), there is no known episode 
of dike intrusion to within a few hundred meters of the surface in the Yucca Mountain region 
that has not been accompanied by an extrusive event. Thus, there is no evidence in the Yucca 
Mountain regional geologic record to suggest that dike intrusions without accompanying 
eruptions occur 2 to 5 times more frequently than eruptions (BSC 2003 [163769], Section 
6.3.2.1). An alternative interpretation of the San Rafael volcanic field is also presented in 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada (BSC 2003 [163769], 
Section 6.3.2.1), which supports an intrusion/extrusion ratio as being closer to 1. This 
interpretation assumes that it is likely that many individual intrusive/extrusive events are 
represented at San Rafael, where some portion of a dike system erupted during an event while 
other portions of the same dike did not erupt. This interpretation is more consistent with the 
geologic record of the Yucca Mountain region, as demonstrated at the Paiute Ridge analogue 
complex. 
Analyses in the report Characterize Eruptive Processes at Yucca Mountain, Nevada (BSC 2003 
[166407]) assume that a plausible eruption during the postclosure performance period would be 
of the same character as Quaternary basaltic eruptions in the Yucca Mountain region. Eruptive 
styles and magmatic composition of the Lathrop Wells volcano, the most recent in the region, are 
emphasized as being the most characteristic. A new volcano would, therefore, contain some 
combination of scoria cones, spatter cones, and lava cones on the surface and one or more dikes 
in the subsurface. Additional assumptions regarding the character of a future eruption focus on 
the use of data from a variety of analogue volcanoes and simplifications for a stylized plausible 
eruption. These include conduit diameter, dike width, the number of dikes associated with 
formation of a new volcano, magma chemistry, water content of magmas, gas composition, 
magma physical properties, ascent rate, fragmentation depth, mean particle size, and eruption 
duration, among others. This is an example of analogue information being used as direct 
parameter input into models, where the input consists of assumptions based on analogues. 
The ASHPLUME computer code (Versions 1.4LV and 2.0) is used in estimation of the aerial 
density of an ash deposit. Ash-thickness data collected after the 1995 eruption of Cerro Negro, in 
Nicaragua, provided an opportunity to use the ASHPLUME code in simulating the eruption 
(CRWMS M&O 2000 [152998], Figure 6). The application of this analogue information is 
discussed further in Section 15. 
14.4 USE OF ANALOGUES IN BOUNDING EFFECTS OF SEISMICITY ON A 
GEOLOGIC REPOSITORY 
Damage from ground shaking caused by an earthquake results largely from shear waves. Density 
contrasts along the path the shear waves follow from the earthquake source to the surface affect 
the amplitude of the waves. As the wave moves from dense rock at depth to less dense, more 
porous, and unconsolidated compressible material near the surface, the speed of the wave is 
reduced. With decreasing speed the kinetic energy of the wave is maintained by increasing 
amplitude, thus giving rise to increased shaking and intensity of damage. At the surface the 
amplitude of a shear wave will be about twice as large as at depth (Stevens 1977 [154501], p. 
20). It follows that if the dimensions of an underground opening are considerably less than the 
wavelength of a shear wave, the shaking effects generated by the amplitude of motion will 
likewise be considerably less. The decrease in the effects of shear waves with increasing depth is 
comparable to the similar effect observed in ocean waves, which decrease in intensity and 
amplitude with the depth of water. A consequence of this is that the damage reported in shallow, 
near-surface tunnels is greater than that reported in deep mines (Pratt et al. 1978 [151817], p. 
26). 

There are numerous examples in the literature of underground structures withstanding damage 
from earthquakes that caused relatively greater damage at the ground surface (Eckel 1970 
[157493]; Stevens 1977 [154501]; Sharma and Judd 1991 [154505]; Pratt et al. 1978 [151817]; 
Power et al. 1998 [157523]). Three earthquakes of recent decades, the Alaskan earthquake of 
March 28, 1964, the Tang-Shan, China, earthquake of July 28, 1976, and the Kobe, Japan, 
earthquake of January 16, 1995, clearly demonstrate the ability of underground structures to 
withstand the ground vibrations associated with severe seismic activity. 
In the Alaskan earthquake, no significant damage was reported to underground facilities, 
including mines and tunnels, as a result of the earthquake, although some rocks were shaken 
loose in places (Eckel 1970 [157493], p. 27). Coal mines in the Matanuska Valley were 
undamaged as was the railroad tunnel near Whittier and the tunnel and penstocks at the Eklutna 
hydroelectric project. A small longitudinal crack in the concrete floor of the Chugach Electric 
Association tunnel between Cooper Lake and Kenai Lake is believed to have been caused by the 
earthquake. These reports of little or no damage to underground structures from the Alaskan 
earthquake are significant because this earthquake was one of the largest (magnitude 8.5) to 
occur in the United States and the associated surface damage was extreme (Pratt et al. 1978 
[151817], p. 32). 
The July 28, 1976, earthquake in the heavily industrial city of Tang-Shan, China, had a 
magnitude of 7.8. Surface intensities at Tang-Shan were such that in the area where the strongest 
shaking occurred, 80% to 90% of the surface structures collapsed. However, for important 
engineered structures immediately below the surface, there was generally no serious damage 
regardless of the depth or size of the structure (Wang 1985 [151821], p. 741). 
The third example is the more recent Kobe, Japan, earthquake of January 16, 1995. Tunnels in 
the epicentral region of the Kobe earthquake (magnitude 6.9) experienced no major damage or 
even partial collapse for peak ground accelerations (PGAs) measured at the surface of ~0.6 g 
(Savino et al. 1999 [148612]). 
A more site-specific, although smaller-magnitude, example was the Little Skull Mountain 
earthquake of June 29, 1992. This earthquake had a magnitude of 5.6 and occurred about 20 km 
from Yucca Mountain. Examination shortly after the earthquake of the interior of X-tunnel (125 
m deep) in the epicentral region indicated no evidence of damage in the tunnel that could be 
associated with the earthquake (Savino et al. 1999 [148612]). 
The understanding of the response of underground openings to seismic events has advanced 
greatly in the last 15 years. Sharma and Judd (1991 [154505], pp. 272275) examined damage 
trends of underground facilities to seismic effects in an effort to aid future design of such 
facilities. They created a database consisting of 192 reported underground observations from 85 
earthquakes throughout the world (Sharma and Judd 1991 [154505], p. 275). To examine the 
influence of seismic effects on underground openings, they used the measure of PGA that may 
be expected to occur at the surface directly above the underground location. The possibility of 
damage was examined as a function of (1) thickness of overburden, (2) predominant rock type, 
(3) type of ground support, (4) earthquake magnitude, and (5) epicentral distance of the 
earthquake. 

On the basis of observations from this collection of data, Sharma and Judd (1991 [154505], p. 
275) concluded that (1) damage incidence decreases with increasing overburden depth; (2) 
damage incidence is higher for unconsolidated colluvium than for more competent rocks; (3) 
internal tunnel support and lining systems appeared not to affect damage incidence; (4) damage 
increases with increasing earthquake magnitude and decreasing epicentral distance (increasing 
PGA); (5) no or minor damage can be expected for peak accelerations at the ground surface less 
than about 0.15 g. Data presented by Sharma and Judd (1991 [154505], Figure 7) indicate that 
damage to underground facilities at the depth for the repository is rare, even at accelerations of 
0.4 g. These findings confirmed those of Stevens (1977 [154501], p. 36) and Pratt et al. (1978 
[151817], p. 26), who suggested that the host material for an underground facility may be 
important in predicting the amount of damage caused by the shaking associated with 
earthquakes. 
Although their observations contained 98 cases with no damage, Sharma and Judd (1991 
[154505], p. 275) also acknowledge that their data set is biased towards occurrence of damage 
because there must be literally hundreds of other instances where no damage occurred but 
observations were not documented (Sharma and Judd (1991 [154505], p. 275). Two cases of 
moderate and heavy damage were reported in tunnels located at a depth of about 210 m near 
Santa Cruz, California, following the 1906 San Francisco earthquake. Based on the epicentral 
distance of 110 km, a PGA of 0.09 g was estimated. Generally, this PGA would be correlated 
with a No damage case; however, the epicentral distance on which the PGA estimate was 
based did not take into account the close proximity to the ruptured San Andreas Fault. Two other 
cases of damage also required further explanation. Damage reported for a mine in Idaho and the 
ERP Mine in the Witwatersrand, South Africa, at depths of 1,350 m and 3,000 m, respectively, 
was probably caused by rock-burst activity rather than a seismic event. This activity is usually 
pronounced in deep mines and generally can be recognized from the relatively high frequency 
content of the recorded accelerograms (Sharma and Judd 1991 [154505], p. 274). Stevens (1977 
[154501], p. 33) quotes N.G.W. Cook of the South Africa Chamber of Mines as stating, All the 
evidence indicates that earth tremors, rock bursts, and bumps arose in the Witwatersrand as a 
result of mining and have followed the pattern of mining in terms of frequency of incidents and 
epicentral position and focal depth. 
Power et al. (1998 [157523]) collected extensive data on seismic ground-shaking-induced 
damage to bored tunnels using more recent data from better instrumented earthquakes than was 
possible for Sharma and Judd (1991 [154505]). Power et al. (1998 [157523]) found that for 
ground motion with PGAs less than 0.2 g, there was little or no damage in tunnels, and for PGAs 
of 0.20.6 g, damage varied from slight to heavy (Power et al. 1998 [157523], Section 1.2). At 
even greater accelerations the damage only ranged from slight to moderate. For example, wellconstructed 
tunnels near Kobe, Japan, experienced PGAs of about 0.6 g but suffered no major 
damage. 
In addition to damage caused by ground vibration, underground tunnels can be damaged by fault 
displacement and by earthquake-induced ground failure, such as liquefaction or landslides at 
tunnel portals, which are not considered an issue at Yucca Mountain. In three instances of heavy 
damage from the 1923 Kanto, Japan, earthquake, observation of damage (with PGA equal to 
0.25 g) may have resulted from landsliding. In the other two observed occurrences of heavy 
damage surveyed by Power et al. (1998 [157523]), tunnel collapse occurred in the shallow 

portions of the tunnels. Damage to underground openings is inevitable only when the 
underground facility is displaced by a fault (Stevens 1977 [154501], p. 35). Carpenter and Chung 
(1986 [154504]) strongly recommend that faults with the potential for movement be avoided, 
which is consistent with design criteria for the repository at Yucca Mountain (BSC 2001 
[155664], Section 1.2.2.1.5; McConnell and Lee 1994 [110957]). 
The previous summary shows that tunnels withstand ground vibration well. However, tunnels in 
solid rock are susceptible to changes in hydrogeologic conditions and may be flooded as a 
consequence of ground shaking. Thus, although there may have been no apparent damage to the 
structure, there is a probability of increased fracture density in rocks surrounding the tunnels 
(Mumme 1991 [157494], p. 77). The potential for changes to the hydrogeologic system caused 
by fault displacement to affect radionuclide transport in the UZ at Yucca Mountain has been 
examined in the report, Fault Displacement Effects on Transport in the Unsaturated Zone 
(CRWMS M&O 2000 [151953]). 
Even near the surface, damage from ground shaking may be slight if the rock is competent. For 
example, Mitchell Caverns, in the Providence Mountains of California, southwest of Las Vegas, 
sustained only minor damage in the October 16, 1999, Hector Mine earthquake (magnitude 7.1). 
The earthquake epicenter was only 30 miles (48 km) away. Damage was limited to a few 
stalactites being shaken from the ceiling at El Pakiva cave. At El Pakiva, the earthquake 
loosened some rocks from the face around and above its entrance (Figure 14-2), but the partial 
occlusion of its entrance by boulders was the result of a previous earthquake (Simmons 2002 
[157544], p. 124). Another cave at Mitchell Caverns, Tecopa, experienced rockfall. The rockfall 
may be related to seismic events, but not to recent ones, because in some areas columns have 
been recemented by dripstone, and dripstone has begun to form on the ceiling from which the 
blocks fell. However, the area of cave floor covered by fallen blocks is much smaller than the 
total area of the cave, and fallen blocks have not obliterated the cavity opening. 
Two final examples of the application of natural analogues to building confidence in the ability 
of a geologic repository at Yucca Mountain to withstand damage from ground vibration and 
faulting are the following. The scientific analysis report Drift Degradation Analysis (BSC 2001 
[156304], Attachment VII) confirmed results of a rockfall model using information from natural 
analogues. The DRKBA code, used to model rockfall probabilities, involves a quasi-static 
method of reducing the joint-strength parameters to account for the seismic effect. This method 
was verified based on the test runs using the dynamic functions of the distinct element code 
UDEC. The comparisons between the results from the dynamic and quasi-static analyses showed 
a consistent prediction of block failure at the opening roof. The seismic effect on both the size 
and number of blocks in the rockfall model is relatively minor. This is consistent with 
information from natural analogues. 
The scientific analysis report Effects of Fault Displacement on Emplacement Drifts (CRWMS 
M&O 2000 [151954]) included a literature survey on accommodating fault displacements 
encountered by underground structures such as buried oil and gas pipelines, which provide 
analogues for potential emplacement drift responses to fault offset. 
The value of examining information on rockfall resulting from underground nuclear explosions 
(UNEs) was considered for this report. While an investigation on this topic may be fruitful, there 

are significant differences between UNEs and earthquakes in terms of frequency content of the 
ground motion and the duration of shaking. These differences make the use of UNE results less 
relevant than results from earthquakes, although the effects of UNEs are better instrumented and 
documented than the effects of earthquakes. 
14.5 SUMMARY AND CONCLUSIONS 
Use of natural analogues is a major investigative tool in Yucca Mountain volcanism studies. 
Analogues have been used to assess the probability of dike eruption, plausible eruptive styles, 
eruptive parameters, and magma compositions, and have also been used to increase confidence 
in use of the ASHPLUME code for simulation of an eruption. Examples from observations of 
underground openings demonstrate that such openings are able to withstand ground shaking for 
even high PGAs. The ability to withstand ground shaking is increased by thickness of 
overburden, competence of material (rock versus colluvium), decreased earthquake magnitude, 
and increased distance of the opening from the earthquake epicenter. Underground openings may 
be damaged by landsliding or liquefaction associated with an earthquake, if the depth of the 
opening is relatively shallow. Underground openings are inevitably affected by fault 
displacement when the opening intersects a fault. Collateral damage by ground shaking can also 
be caused when ground shaking alters hydrogeologic conditions by increasing fracture density 
and permeability, and thereby increasing fracture flow to an underground opening. The bulk of 
evidence from analogue examples of underground openings, particularly in settings similar to 
Yucca Mountain, such as the Little Skull Mountain earthquake, demonstrates that damage to 
repository drifts by ground shaking during the post-closure period would be minimal or unlikely. 

NOTE: The seismograms for the surface and underground are to the same vertical scale. M = magnitude; . = 
distance; Z = amplitude; N = N-S; E = E-W; ESF = Exploratory Studies Facility. 
Source: Modified from Savino et al. 1999 [148612]. 
Figure 14-1. Recordings of Frenchman Flat Earthquake at the 
Ground Surface and the Thermal Test Alcove of the ESF 

Source: Simmons 2002 [157578], SN-LBNL-SCI-108-V2, p. 9. 
Figure 14-2. Entrance to Mitchell Caverns, El Pakiva Portal, Showing Fallen Blocks That Partially 
Occlude the Entrance 

15. APPLICATION OF NATURAL ANALOGUES FOR THE 
YUCCA MOUNTAIN PROJECT 
15.1 INTRODUCTION 
This section addresses the application of natural (including anthropogenic) analogues to geologic 
repository programs. Section 15.2 provides an overview of the applications for which natural 
analogues are suitable. Section 15.3 tells how natural analogues have been applied in geologic 
nuclear waste disposal programs worldwide. Section 15.4 reviews the application of natural 
analogues to past iterations of performance assessment (PA) and the supporting process models 
for Yucca Mountain. Section 15.5 identifies those model components, as stated by process 
modelers, that could benefit from confidence built through natural analogues. Section 15.6 
categorizes the way natural analogue information has been used in this report. Section 15.7 
presents a final summary and conclusions. 
15.2 OVERVIEW 
Figure 15-1 illustrates the flow of information from natural analogues and other site 
characterization data into PA models. The figure indicates that natural analogues provide both 
qualitative and quantitative information, as this report has demonstrated through many examples 
in the preceding sections. Stated in words, the stages or components in the development of a PA 
code (shown in Figure 15-1) are the following: 
Construction of a conceptual model that describes the system and includes all of the 
important processes and their interactions. 
Translation of conceptual models into mathematical models and encoding those models 
in the form of a numerical code. 
Acquisition of input data for all the variable and constant parameter values included in 
the numerical code. 
Verification of the numerical correctness of the computer code. 
Validation of the codes applicability to the repository system in assessing its ability to 
predict future conditions. 
The ways in which analogues can be or have been used to assist in 1, 3, 4, and 5 above are 
discussed below. 
Model construction: In the stage of model construction, natural analogues can be used to tell the 
PA modeler: 
Which processes and process interactions to include 
Which processes are likely to be dominant and which are of secondary importance 

The spatial and temporal scales over which the model should perform 
Whether the basic premises of the model hold up under extrapolation to long time periods. 
Some of the analogues discussed in Sections 4, 6, 7, 9,10, 11, and 12 relate to identification of 
processes that are or may be included in models. 
Data acquisition: Information derived from natural analogue studies is often semi-quantitative. 
For this reason it cannot often directly satisfy the parameter value requirements of a PA code. 
However, laboratory data have uncertainty related to the lack of similarity between the 
laboratory and repository systems. Therefore, a role for analogues in data acquisition is to 
provide a measure of validation for the laboratory data. Even though the analogue data may be 
imprecise, they can be used to give confidence in the reliability of the laboratory data. An 
example of this application was given in Section 4, describing the similarity between uraninite 
alteration phases produced in laboratory dissolution experiments and those uraninite alteration 
phases identified in rock samples at the Nopal I, Pea Blanca analogue site. 
Model validation: Thermodynamic solubility and speciation codes and databases have been 
extensively applied in a number of natural analogue studies (e.g., Maqarin, Poos de Caldas, 
Koongarra). Natural analogues can help determine whether the solubility-controlling mineral 
species and complexes in solution (generally specified by hydrochemical databases or from 
theoretical or laboratory experiments) are appropriate to the site-specific conditions being 
modeled, and whether or not mineral phases and/or ionic species in solution indicate chemical 
equilibrium has been achieved or whether the system is controlled by kinetics. 
A subcategory of modeling studies is database evaluation. One application of natural analogues 
in this category is the evaluation of geochemical models and numerical tools used in describing 
the predicted migration of radionuclides in a repository system. Blind predictive modeling 
comparisons are a means of evaluating geochemical databases. For instance, Bruno et al. (2001 
[157484]) reviewed and compared the results obtained from the blind prediction modeling 
exercise carried out for seven natural analogue studies relevant to European repository concepts: 
Oman; Poos de Caldas, Brazil; Cigar Lake, Canada; Maqarin, Jordan; El Berrocal, Spain; Oklo, 
Gabon; and Palmottu, Finland. The blind predictive model exercise (Bruno et al. 2001 [157484]) 
was able to improve conceptual and numerical models to identify relevant radionuclides to major 
component phases in the rock-water systems of interest. The modeling group achieved a 
consensus concerning the most appropriate methodology for approaching solubility-limited 
calculations and identified the main requirements for acquiring improved site characterization 
data to describe radionuclide mobility. 
Tangible illustrations: Natural analogues also have an important role, beyond their application to 
PA, in providing illustrative information to a broad range of audiences, including the general 
public. Natural analogues, or comparisons with natural systems, are frequently mentioned as 
important components of the process of evaluation and acceptance of disposal concepts. In 
quoting the IAEA (1999 [157485]), Miller et al. (2000 [156684], Section 6.1) stated, Among all 
levels of reviewer, from technical peer review panels to nontechnical audiences, there is a clear 
belief that PAs are only credible if shown to have strong natural parallels. Recognition of the 
important processes and events that control the repository behavior can be demonstrated from 

illustrative geological analogues. Natural analogues assist in the public understanding of 
timescales applicable to radioactive decay. These real world examples are important because the 
extended time periods of interest to disposal are generally longer than those in our normal range 
of experience. 
15.3 PERFORMANCE ASSESSMENT APPLICATIONS OF ANALOGUES IN 
GEOLOGIC DISPOSAL PROGRAMS WORLDWIDE 
Several reviews have examined the level of direct and acknowledged use of natural analogues in 
published PA documents of geologic repository programs worldwide (e.g., McKinley and 
Alexander 1996 [157486]; IAEA 1999 [157485]). Results of these reviews indicated that very 
few total system PA documents provided detailed discussion of how analogues were used to 
support specific aspects of the assessments, and some PA reports did not discuss how natural 
analogues support geological disposal in even a general way. 
An indirect use of analogues in PA in some programs is in the development of scenarios, where 
identification of features, events, and processes (FEPs) of importance to repository evolution are 
required (Chapman et al. 1995 [100970]). The role of analogue information in this case is to 
provide supplemental evidence to support the inclusion or exclusion of different FEPs in 
scenarios to be analyzed for PA. An example of this application of analogues is the scenario case 
for criticality in a waste repository. This scenario was screened out using, in part, understanding 
of processes that occurred at Oklo (see Section 4). 
Miller et al. (2000 [156684], Section 6.1), referring to IAEA 1999 [157845], summarized the use 
of analogues for model development, data provision, and model validation in ten PAs over the 
past two decades. These included KBS-3 (Sweden, 1983); Projekt Gewhr (Switzerland, 1985); 
SKB-91 (Sweden, 1991); TVO (Finland, 1991); AECL EIS (Canada, 1994); Kristallin-I 
(Switzerland, 1993); NRC IPA (USA, 1995); TILA-99 (Finland, 1999); SR-97 (Sweden, 1999); 
and SFR (Sweden, 1999). All but one of these PAs used analogues in conceptual model 
development or scenario development. All of the PAs used data from analogues, either as 
bounding conditions or as direct parameter values. Seven of the ten PAs used analogues for blind 
predictive modeling or for the evaluation of models and databases as part of model validation. 
The NRC, for instance, used natural analogues in the following ways: 
In scenario development for volcanism, as an alternative source-term conceptual model 
using Pea Blanca data (Murphy and Codell 1999 [149529]). 
To establish relative importance of microfractures and matrix transport at Pea Blanca, 
Mexico. 
As backup for vapor-phase transport at the Valles Caldera, New Mexico. 
To identify secondary phases for long-term release at Pea Blanca. 
For model testing of elemental transport in unsaturated media at Akrotiri, Greece 
(Murphy 2000 [157487]). 

Miller et al. (2000 [156684], Table 6.1.1) noted that few of the analogue applications were 
explicitly mentioned in the top-level documents associated with these PAs. The lack of 
acknowledgment of these applications of analogues by PAs is evident from a disconnect between 
the examples of uses shown in the IAEA (1999 [157485]) report and the applications noted in the 
reports conclusions. Thus, it appears that the role of natural analogues in providing a general 
conceptual basis for the geological disposal of radioactive waste and for specific waste isolation 
mechanisms is largely unacknowledged. There are only a few clear examples of parameter 
values being provided by natural analogues that may be directly input to an assessment model, 
such as measured matrix diffusion and metal corrosion rates. A semi-quantitative use of natural 
analogues has been to provide bounding limits to the ranges of parameter values obtained from 
laboratory studies. The most valuable quantitative role of natural analogues, which cannot be 
replicated in laboratory systems, is to provide bounding estimates for validation of PA models. 
So far, this has only been seriously attempted for equilibrium geochemical modeling (e.g., at 
Poos de Caldas, Oman, Maqarin, and El Berrocal). 
15.4 PREVIOUS YMP INCORPORATION OF NATURAL ANALOGUES 
Process modelers, as users of analogue information, can and have played an important role in 
determining how analogues can best be used to support PA and design groups in reducing 
uncertainties in the long-term behavior of natural and engineered systems. 
In the past, the YMP has used analogues for testing and building confidence in conceptual and 
numerical process models in a number of ways: 
Yucca Mountain as a self analogue: Mineral alteration zones that formed during 
cooling of Timber Mountain ash-flow tuffs were shown to be the same as those 
expected to form under the thermal conditions predicted by numerical codes (Bish and 
Aronson 1993 [100006]). 
Thermochemical data: Data from the Wairakai, New Zealand, geothermal field were 
used to build confidence in thermodynamic parameters for silica minerals in databases 
used in geochemical modeling (Carroll et al. 1995 [109627]). 
Spent fuel alteration parageneses: Mineral phases determined in laboratory experiments 
were compared to those of Nopal I, at Pea Blanca (Figure 4-1). The results of these 
studies (summarized in Section 4) have increased the confidence in models describing 
spent-fuel alteration. 
Saturated zone transport: Scoping calculations were conducted for the Pea Blanca site 
using the same numerical model that was used to assess total system performance of the 
potential Yucca Mountain repository. The model attempted to predict the transport of 
99Tc, which is expected to be a conservative ion that would be released from the waste 
inventory. Results of the modeling indicated that both 99Tc and some forms of uranium 
may be detected in groundwater close to the Nopal I mine at Pea Blanca (CRWMS 
M&O 2000 [153246], Appendix C, Figure C-12). The scoping predictions were 
sensitive to the surface area assumed for the inventory of leachable mineral species, 
because a reduction of mineral surface area led to a reduction in both uranium and 99Tc 

concentrations (CRWMS M&O 2000 [153246], Appendix C). The scoping study 
predictions differ from analyses of groundwater samples collected in the 1980s from a 
monitoring well 1,300 m downgradient from the Nopal I mine, which detected very low 
concentrations of uranium. To corroborate the model results for uranium and possibly 
technetium, the scoping simulations will be rerun using additional data from analyses 
of water samples collected from wells at and immediately downgradient from the Nopal 
I ore deposit (see Section 10.4). 
Verification of models describing volcanism: Immediately after a 1995 volcanic 
eruption at Cerro Negro, an active basaltic cinder cone in Nicaragua, the thickness of 
volcanic ash deposited during the eruption was measured. The ash thickness data 
provided an opportunity to use the ASHPLUME code (CRWMS M&O 1999 [132547]) 
to simulate the eruption. The goal was to compare calculated ash deposition predicted 
using the ASHPLUME code to the ash thickness recorded in an actual ashfall event 
from a small-volume basaltic volcano. Cerro Negro is analogous in size and 
morphology to a volcanic feature that could form as the result of a volcanic eruption in 
the vicinity of Yucca Mountain, although the intra-continental arc magmatism that 
forms the tectonic setting for Cerro Negro is different from the Basin-and-Range style 
tectonics of the Yucca Mountain area. Two versions of the ASHPLUME code that 
employ a two-dimensional diffusion model were used. The results of both versions 
compared well with the observed data for distances from the volcanic event greater 
than 10 km (CRWMS M&O 2000 [153246], Appendix C, Figure C-1). For distances 
less than 10 km, ASHPLUME results calculate ash thickness values greater than the 
observed data, possibly because ASHPLUME assumes a constant wind speed and 
direction for a given simulation, whereas the actual situation reflected a shift in wind 
direction, and possibly velocity, during the eruption. Nevertheless, the results in general 
showed that the ASHPLUME model can reasonably predict the ashfall distribution of a 
basaltic cinder cone similar to Cerro Negro. This result increases the confidence in 
ashfall calculations that could be used to simulate possible ash-producing eruptions 
either near or through a repository at Yucca Mountain. 
Analogues were included in discussions of multiple lines of evidence in the FY 01 Supplemental 
Science and Performance Analyses, Volume 1: Scientific Bases and Analyses (BSC 2001 
[155950]). To a large degree, these analogues have been referenced in this report in Sections 4, 
6, 7, 8, 9, 10, 11, 12, 13, and 14. Analogues have also been used to provide multiple lines of 
evidence in support of both analysis and model reports (AMRs); in screening arguments for 
inclusion or exclusion of FEPs in total system PAs (TSPAs); in the quantification of 
uncertainties (BSC 2001 [155950]); and in expert elicitations such as Probabilistic Volcanic 
Hazard Analysis for Yucca Mountain, Nevada (CRWMS M&O 1996 [100116]); Probabilistic 
Seismic Hazard Analyses for Fault Displacement and Vibratory Ground Motion at Yucca 
Mountain, Nevada (USGS 1998 [100354]); and An International Peer Review of the Biosphere 
Modelling Programme of the US Department of Energy's Yucca Mountain Site Characterization 
Project, Report of the IAEA International Review Team (IAEA 2001 [155188]). 

15.5 YMP IDENTIFIED NEEDS 
Areas identified for the TSPA-VA in which analogue studies might contribute to evaluating of 
and building confidence in PA models include: 
Seepage threshold and the fraction of waste packages contacted by seeps (including 
seepage enhanced by thermally induced drift collapse) 
Alteration of hydrologic properties by mineral precipitation or dissolution 
Sorption onto fractures 
The role of colloid filtration in reducing radionuclide migration 
Alloy 22 corrosion 
Neptunium solubility 
Saturated zone (SZ) dilution. 
PA requirements for natural analogues were also considered for the TSPA-SR and the TSPA-LA. 
A meeting was held in January 2001 to integrate PA needs for building confidence in process 
models, including areas where natural analogues could contribute. This report includes examples 
of natural analogue contributions to the stated needs identified by PA studies. 
15.6 APPLICATIONS FROM THIS REPORT 
Table 15.1 is a compilation of the ways in which analogues have been used in this report. The 
analogues are listed by chapter and are categorized as to their use in building conceptual models 
or understanding of processes, development of data parameters and their use in TSPA, or use for 
model validation. It is evident that the majority of uses of analogues for YMP has been in the 
understanding of which processes to model and how to incorporate them into PA. Less frequent 
has been their use in model validation, and even less frequent is their use directly in PA. The 
categorization on this table should not be surprising because it corresponds to the frequency of 
application of analogues to these steps in TSPA in the international community, as stated in 
Section 15.3 and in IAEA (1999 [157485], Section 6). 
15.7 SUMMARY AND CONCLUSIONS 
This section recapitulates the most important points that were summarized at the end of each 
preceding section, along with suggestions for areas where analogues could increase needed 
confidence in process models. Because no new material is introduced in this section, the 
references to these conclusions are not included. The reader should refer to the section that 
provides the source of these summary points, or conclusions, or to the Document Input 
Reference System (DIRS). 

15.7.1 Drift Stability (Section 3) 
The ability of underground openings to remain open and stable under ambient conditions 
depends on a number of variables, including: (1) rock strength; (2) the size, shape, and 
orientation of the opening; (3) orientation, length, and frequency of fracturing; and (4) 
effectiveness of ground support. Radiometric dating of cave floor minerals at Carlsbad Caverns 
and Lechuguilla Cave indicates that natural openings larger than those proposed for repository 
drifts at Yucca Mountain have remained stable and open for millions of years. Collapse of the 
roof of an opening tends to occur where the fracture density is high and the overburden is thin, as 
is the case with some lava tubes. Independent factors that contribute to the size of a rockfall 
block are fracture spacing, rock type, rock texture, and the size and shape of the opening. 
Paleolithic flint mines (~4,000 to 3,000 BC), Roman mines and aqueducts, and other 
anthropogenic examples demonstrate that man-made underground openings can also exist for 
thousands of years. 
15.7.2 Waste-Form Degradation (Section 4) 
The reaction path of alteration of spent nuclear fuel at Yucca Mountain will be similar to that of 
geologically young, Pb-free uraninite, with schoepite and becquerelite forming as intermediate 
products, followed by uranyl silicates. The uraninite and its alteration products found at the 
Nopal I uranium deposit at Pea Blanca have these characteristics. Therefore, the uranium 
alteration paragenetic sequence at the Nopal I uranium deposit at Pea Blanca is a good analogue 
for the alteration of uranium oxide spent fuel. 
Secondary mineral formation was responsible for incorporating uranium in stable mineral phases 
at Shinkolobwe, Zaire, where 50 secondary uranium-bearing phases could be identified. Because 
of its great age (1,800 Ma), radiogenic lead-bearing phases played a role in sequestering 
uranium. At Oklobondo, Gabon, and Shinkolobwe, other secondary phases, particularly (U,Zr) 
silicates, formed stable phases. 
The concentrations of fission products can be used as tracers in rock and groundwater 
surrounding uraninite and provide a satisfactory approach to estimating natural dissolution rates. 
When this approach was evaluated at Cigar Lake, Canada, and Koongarra, Australia, under 
reducing and oxidizing conditions, respectively, the dissolution rate at Koongarra was found to 
be more rapid. Although use of the fission product tracer method has not been reported for Oklo, 
other lines of evidence indicate that dissolution has been slight at Oklo over the past 
approximately 2 billion years. Whether or not deep oxidizing waters at Oklobondo have 
increased the dissolution of uraninite and created an oxidized suite of minerals is a subject that 
could be evaluated. 
Under radiolysis conditions occurring at the time of reactor criticality at Oklo, only several 
percent of uranium was estimated to have been mobilized for transport from its original site, 
which experienced far more extreme conditions than those anticipated at Yucca Mountain. 
Likewise at Oklobondo, radiolysis effects at the time that the natural reactor was active appear 
confined to rare earth element migration from the core to the rim of minerals containing these 
elements. 

Based on analyses of conditions that occurred at Oklo, it was shown that criticality of spent fuel 
either within waste packages or by reconcentration of uranium outside of the waste package has 
a very low likelihood because both the probability of certain processes required to achieve 
critical conditions occurring simultaneously or sequentially is extremely small and certain 
required conditions are mutually exclusive. 
Although natural glasses are somewhat different in composition from borosilicate nuclear waste 
glass, studies of natural glass alteration indicate that glass waste forms will be stable in a 
repository environment at Yucca Mountain. In both natural and borosilicate glass, higher 
stability is favored by higher silica and alumina content and by lower alkali and water content. 
However, analogue studies have not considered radiation effects on glass over long time periods 
and, thus, cannot be used to confirm experimental results showing that radiation has little effect 
on waste glass stability. 
15.7.3 Waste-Package Degradation (Section 6) 
The analogues to common metals presented in Section 6 serve mainly to demonstrate that under 
ambient to slightly elevated temperatures, these metals will be stable for thousands of years, even 
under oxidizing conditions. The survival of metal archaeological artifacts over prolonged periods 
of time is related to the corrosion-resistant properties of metals and metal alloys, the 
development of protective passive film coatings with the onset of corrosion, and the location of 
artifacts in arid to semi-arid environments. Such features have been used in the selection of 
materials and design configuration to enhance the durability of waste packages at Yucca 
Mountain. 
The survival of the naturally occurring ordered Ni-Fe alloy in josephinite for millions of years, 
with only relatively minor amounts of surface oxidation, indicates that this material is highly 
resistant to oxidation and other forms of corrosion that occur in its geologic environment. While 
the composition of this metal differs from Alloy 22 (in that it does not contain Cr, Mo, or W), it 
does provide evidence that a similar alloy can remain passive over prolonged periods of time 
under similar conditions. 
The potential instability of chromium-bearing materials is illustrated by the observed natural 
release of chromium from chromite in the Sierra de Guanajuato ultramafic rocks under ambient 
conditions. Corrosion appears to be concentrated along exsolution rims, analogous to structural 
defects on metal surfaces. However, although the chromite has undergone some alteration, it has 
survived for over 140 million years. 
15.7.4 Engineered Barrier System Components (Section 7) 
The highly corrosion-resistant nature of titanium has been demonstrated by long-term 
experiments conducted on a range of metal alloys in wells at the Salton Sea geothermal field, 
California. This anthropogenic example supports the selection of titanium alloys for the 
construction of a corrosion-resistant drip shield for the Engineered Barrier System (EBS). 
Although the proposed devitrified welded tuff for the invert ballast does not have high 
concentrations of zeolite and clay minerals, the high surface area of crushed tuff will retard 
radionuclide transport through sorption. One example of absorption of actinides in a gravel bed 

at Los Alamos, New Mexico, provides qualitative evidence of retardation at the contact between 
an invert-like material and underlying bedrock. 
Because the use of cementitious material in the EBS and its environs is restricted to grout for 
securing rock bolts in the emplacement drifts, hyperalkaline conditions are not expected to 
develop at Yucca Mountain. However, through reactive-transport modeling of the Maqarin site, 
it has now been demonstrated that a model can reproduce the same suite of cement minerals, 
hyperalkaline water compositions, and pH that were found in the field. This result builds 
confidence in use of such a model for analogous conditions at other sites. 
The Poos de Caldas analogue illustrated that iron-bearing colloids may retard the transport of 
uranium and other spent-fuel components by forming colloids that are then filtrated from 
suspension at short distances. Degradation of steel structural elements in the EBS could 
conceivably contribute to this process. 
15.7.5 Seepage (Section 8) 
An important variable for preservation in underground openings is relative humidity. If relative 
humidity in the emplacement drift is kept below 100% by ventilation, then seepage of liquid 
water would be reduced or completely suppressed. Most caves are close to, but below 100% 
humidity. Thus, the amount of seepage in caves found in unsaturated environments would be 
expected to be low. This would also be true at Yucca Mountain while ventilation is maintained. 
The findings in Section 8 support the hypothesis that most of the infiltrating water in the 
unsaturated zone (UZ) is diverted around underground openings and does not become seepage. 
The analogues show that this is true even for areas with much greater precipitation rates than that 
at Yucca Mountain. Although examples exist where large amounts of seepage can be observed 
(e.g., the Mission Tunnel and Mitchell Caverns) and cave minerals formed by water are common 
in unsaturated environments, these hydrogeologic settings are significantly different from that at 
Yucca Mountain and, thus, are not appropriate analogues. However, for all of the analogues that 
show some seepage, at least some of the seepage that enters underground openings does not drip 
but rather flows down the walls. In the few instances where dripping has been noted in settings 
that are analogous to Yucca Mountain, the drips can be attributed to asperities in the surface of 
the roof and ceiling of the opening. Whether water flows on walls or drips depends on conditions 
affecting drop formation and drop detachment (e.g., surface tension, roughness angle, 
saturation). Thus, although most water would flow around emplacement drifts at Yucca 
Mountain, the small amount of seepage that does occur would primarily flow down tunnel walls. 
In the few instances where dripping may occur, it would be expected to occur at asperities, also. 
15.7.6 UZ Flow and Transport (Sections 9 and 10) 
Hydrographs of ponded water and 75Se breakthrough curves measured during the LPIT test 
conducted at the Idaho National Engineering and Environmental Laboratory (INEEL) were 
analyzed to determine parameters controlling unsaturated flow and transport. Analysis of these 
data involved building a numerical model using TOUGH2 in a dual-permeability modeling 
approach that has been extensively used to simulate flow and transport at Yucca Mountain. The 
basalt hydrologic properties showed significantly greater variability than the B-C sediment layer 

interbed properties. This implies that the field-scale heterogeneity limits the volume to which the 
spatially averaged basalt parameters could be attributed relative to the B-C sediment layer 
interbed parameters. This may in part result from the fractured-porous dual-continuum nature of 
the basalt in comparison to the porous single-continuum nature of the B-C sediment layer 
interbed. 
The transport model calculations predicted retardation factors for neptunium and uranium that 
are orders of magnitude higher than retardation factors for the other radionuclides at the 
Radioactive Waste Management Complex (RWMC). This result would indicate that very little 
movement of neptunium and uranium should be observed. But detection of these radionuclides at 
depth was inconsistent with their predicted high retardation. Radionuclide transport in the 
surficial sediment zone at the RWMC could be interpreted in a number of ways. One is that 
lateral flow occurred, sweeping out part of the radionuclide plume. Another possibility is that a 
sudden surge of fluid caused by a flooding event released a pulse of radionuclides that 
propagated downward quickly, such that the peak lies at a greater depth than that at which the 
data were collected. The UZ Flow and Transport Model at Yucca Mountain considers a range of 
infiltration rates that are then used to bound the range of percolation flux. Because the Paintbrush 
nonwelded unit (PTn) at Yucca Mountain has a damping effect on downward flow to the 
Topopah Spring welded unit (TSw) and a similar damping effect has not been observed in the 
sedimentary interbeds at the RWMC, it is unlikely that the enhanced transport scenario proposed 
in the INEEL modeling study would occur at Yucca Mountain. 
Data collected to date for the long-lived U-series members indicate limited mobility of uranium 
and its daughters over 10 k.y. timescales at Nopal I. Transport from the uranium deposit to 
fractures has occurred in the past. However, the main transport activity currently observed is 
elevated 226Ra in water samples in proximity to the deposit. The large depletions of 226Ra seen in 
the fractures point to 226Ra mobilization via recoil from fine-grained (sub-micron) U-bearing 
materials in the fracture coatings. The 226Ra concentrations in waters sampled away from the 
deposit are quite low, which is typical for surface waters around the world (Porcelli and 
Swarzenski 2003 [168458]). Hence, the mobilization of radium is a near-field event resulting 
from recoil of the 226Ra from high-uranium regions into fluids. This mode of radionuclide 
mobilization would have a bearing on transport of uranium and its daughters from breached 
canisters at a high-level geologic storage system but would not have a bearing on the transport of 
fission products such as 133Ba, 135Cs, 137Cs, and 90Sr. By analogy to the Pea Blanca 
observations, one would expect to see any mobilized uranium transported locally to fracturefilling 
materials. Recoil effects would raise local concentrations of daughters in the fluids to be 
redeposited/sorbed at some moderate distance away from the recoil site. The Nopal I uranium 
deposit remained largely in place prior to mining operations, indicating limited uranium 
transport. Some of the uranium was remobilized during 2003 drilling operations; however, 
uranium and thorium concentrations in groundwaters away from the drilling operations are low. 
High radium mobility is observed near the surface of the deposit. This mobility appears to be 
related to alpha-recoil from fine-grained, uranium-rich, fracture-filling phases. It is a near-field 
effect resulting from the high uranium contents in fractures. Away from the deposit, low radium 
concentrations are observed in the waters. This indicates that other factors limit radium mobility 
over long distances, such as sorption onto mineral surfaces or co-precipitation with calcium 
fluoride or carbonate minerals. By analogy, it would be expected that similar limits apply to the 
transport of fission products such as 133Ba, 135Cs, 137Cs, and 90Sr. 

15.7.7 Coupled Processes (Section 11) 
Geothermal systems illustrate a variety of thermal-hydrologic-chemical (THC) processes that are 
relevant to Yucca Mountain. Yellowstone and other geothermal systems in welded ash flow tuffs 
or other low-permeability rocks indicate that fluid flow is controlled by interconnected fractures. 
Alteration in low-permeability rocks is typically focused along fracture flow pathways. Only a 
small portion of the fracture volume needs to be sealed by precipitated minerals to retard fluid 
flow effectively. The main minerals predicted to precipitate in the near field of the Yucca 
Mountain repository are amorphous silica and calcite, which are also commonly found as sealing 
minerals in geothermal systems. 
Sealing in geothermal fields can occur over a relatively short time frame (days to years). The 
unsaturated conditions, lower temperatures, and much lower fluid-flow rates predicted for the 
Yucca Mountain system, in comparison to geothermal systems, should result in less extensive 
water-rock interaction than is observed in geothermal systems. Fracturing and sealing occur 
episodically in geothermal systems. Most mineralization at Yucca Mountain is predicted to occur 
soon after waste emplacement (1,000 to 2,000 years) when temperatures would reach boiling (for 
the higher-temperature operating mode) above the emplacement drifts. 
As shown in Section 11.3, THC processes are expected to have a much smaller effect on 
hydrogeological properties at Yucca Mountain than what is observed at Yellowstone. However, 
development of a heat pipe above emplacement drifts at Yucca Mountain under a highertemperature 
operating mode could lead to increased chemical reaction and transport in the near 
field. Reflux and boiling of silica-bearing fluids within the near field at Yucca Mountain could 
cause fracture plugging, thus changing fluid flow paths. Geochemical modeling of fluid 
compositions has been used to successfully predict observed alteration mineral assemblages at 
Yellowstone. THC simulations conducted to date for the Yucca Mountain repository suggest that 
only small reductions in fracture porosity (47%) and permeability (< 1 order of magnitude) will 
occur in the near field as a result of amorphous silica and calcite precipitation. Changes in 
permeability, porosity, and sorptive capacity are expected to be relatively minor at the mountain 
scale, where thermal perturbations will be reduced. This THC result applies to both the higher 
and lower temperature (sub-boiling) operating modes. These predicted changes in 
hydrogeological properties should not significantly affect repository performance. 
At the Paiute Ridge intrusive complex (Section 11.4), the Papoose Lake Sill intruded into Rainier 
Mesa Tuff, and the resulting hydrothermal effects were characterized by low-temperature 
alteration of glass to clinoptilolite and opal, similar to the alteration assemblage present at Yucca 
Mountain. Hydrothermal alteration was confined to a narrow zone close to the sill-host rock 
contact. The pervasive opal veins and associated secondary minerals (e.g., clinoptilolite, calcite, 
cristobalite, etc.) appear to have reduced matrix or fracture permeability in the immediate 
vicinity of the basaltic intrusion. 
Preliminary results of a one-dimensional THC dual-continuum model of the interaction of 
country rock with heat released from an intrusive complex emplaced above the water table 
demonstrated the possibility of forming opal-filled veins with the source of silica derived from 
the matrix of the host rock. However, because of the irregularities caused by kinetic barrier 

effects associated with reaction of glass, it is important to compare and contrast a number of 
different sites to be able to derive general conclusions regarding mineral alteration. 
15.7.8 Saturated Zone Transport (Section 12) 
Only a few of the Uranium Mill Tailing Recovery Act (UMTRA) sites are potentially useful in 
the evaluation of radionuclide transport in the alluvial portion of the Yucca Mountain flow 
system. The conclusions derived from an analysis of the Gunnison site are: (1) a fraction of the 
uranium originating at the site is transported in the alluvial aquifer at a rate similar to the rate at 
which a conservative constituent is transported; and (2) there is little evidence for lateral 
dispersion of contaminants in the downgradient direction. For the New Rifle site, the main 
conclusions are: (1) dilution is a significant process in the downgradient direction; and (2) 
uranium is transported at almost the same rate as conservative constituents. The conclusions 
regarding uranium transport distances relative to conservative constituents must be tempered by 
uncertainties regarding the potential presence of unidentified complexing agents. 
Although several natural analogue studies have demonstrated the effect of sorption and 
precipitation processes on fracture surfaces, none has been able to distinguish clearly between 
these processes or to provide quantitative data on retardation with respect to transport of trace 
elements in natural waters. However, these studies do highlight which phases are most active and 
provide useful information on the effect of interaction between solutes and the rock surface. 
In most studies of natural systems, a proportion of the total uranium, thorium, and rare earth 
elements in the groundwater was associated with colloids. Colloids can serve as sorbers of 
radionuclides, and may be agents either of retardation (Section 7 and Section 15.7.4) or of fast 
transport (Section 12). Unambiguous evidence from natural systems indicating colloidal 
transport over kilometer-scale distances is limited to a few reports. Observations from such 
places as Los Alamos and the Nevada Test Site lend support to the concept that radionuclide 
transport in the SZ can be facilitated by colloids, but, so far, no natural analogue studies have 
been able to quantify the importance of this process. 
15.7.9 Biosphere (Section 13) 
The Chernobyl data on hot-particle dispersal and dust transport showed that radionuclides attach 
to dust particles and move as combined particles. Aspects of models of atmospheric contaminant 
dispersal, radionuclide fallout, radionuclide resuspension, and particle size distributions may be 
relevant to constraining a model for radionuclide resuspension resulting from a possible volcanic 
eruption through the Yucca Mountain repository. 
The use of physical values of the half-life of radionuclides gives conservative estimates of 
radionuclide removal from soils in the Yucca Mountain biosphere model. The increase in the 
concentration of radionuclides in soils during irrigation in the southern Ukraine, where 
environmental conditions are more similar to those at Yucca Mountain than are conditions at 
Chernobyl, confirms the concept of a radionuclide build-up factor used in the Yucca Mountain 
biosphere conceptual model. 
Results of the Chernobyl literature survey suggest that soil type influences the ecological halflife 
of radionuclides in the biosphere, both in regard to soil bioaccumulation factors and 

advective and diffusive transport properties that limit radionuclide transfer to plant roots. With 
respect to rural populations, agricultural methods including irrigation, tillage, and types of crops 
play an important role in resuspension of radionuclides. Resuspended material is likely to 
increase the contamination of plant surfaces. Resuspended radionuclides would increase the 
inhalation dose for agricultural workers, which would be particularly significant for plutonium. 
For potential groundwater contamination pathways at Yucca Mountain, radionuclidecontaminated 
water, which is used as the source of drinking water, irrigation, animal watering, 
and for domestic applications, is expected to increase the likelihood of ingestion uptake of 
radionuclides by humans. Chernobyl data showed that the ingestion pathway constitutes a small 
part of the total radiation dose as the external pathway is predominant within the Chernobyl 
Exclusion Zone. Chernobyl data on the atmospheric distribution of contaminants, their fallout, 
and redistribution in soils and plants may be considered an anthropogenic analogue for the 
potential release of radionuclides caused by a volcanic eruption at Yucca Mountain accompanied 
by atmospheric dispersal of contaminants into the environment through ash fallout on the land 
surface. 
15.7.10 Volcanism and Seismic Effects on Drifts (Section 14) 
Use of natural analogues is a major investigative tool in Yucca Mountain volcanism studies. 
Analogues have been used to assess the probability of dike eruption, plausible eruptive styles, 
eruptive parameters, and magma compositions, and have also been used to increase confidence 
in use of the ASHPLUME code for simulation of an eruption. For seismic effects, examples from 
observations of underground openings demonstrate that such openings are able to withstand 
ground shaking for a peak ground acceleration as high as 0.4 g. The ability to withstand ground 
shaking is increased by thickness of overburden, competence of material (i.e., indurated and 
consolidated rock versus colluvium), decreased earthquake magnitude, and increased distance of 
the opening from the earthquake epicenter. The bulk of evidence from analogue examples of 
underground openings, particularly in settings similar to Yucca Mountain (such as the Little 
Skull Mountain earthquake), demonstrates that damage to repository drifts by ground shaking 
during the postclosure period would be minimal or unlikely. 
15.7.11 Remaining Areas for Increased Process Understanding through Analogue Studies 
The analogue examples and studies presented in this report provide varying degrees of 
confidence in the processes they are intended to support. The investigation of these analogues 
has helped to indicate the directions along which further analogue studies can best be focused to 
address processes that are not fully understood. Key areas where analogues may assist in 
building more confident assessments of processes are the following: 
Irreversible Sorption: PA currently makes the conservative assumption that sorption is 
reversible because no useful data exist that show it to be irreversible. If analogues could 
demonstrate convincingly the conditions under which sorption could be irreversible, 
they would contribute greatly to the realism of models. 

Drift Shadow Zone: The presence of a drift shadow zone is best tested through 
analogue sites that have remained undisturbed over several decades. Suggested sites are 
discussed in Section 9. 
Plume Dispersion: Following the UMTRA study, modeling of different types of plumes 
in alluvium could build confidence in the way plume dispersion is modeled for YMP 
TSPA. Examples could be found with toxic spills or natural analogues such as 
Koongarra. 
Geosphere/Biosphere Interface: Radionuclide behavior at the geosphere/biosphere 
interface could be investigated by natural analogue studies on the migration of 
radionuclides released from spills, leaks, and underground bomb tests and accidents. 
Some sites in Russia may yield these types of data. 
Colloids: Analogue studies suggest that colloids provide an inefficient mechanism for 
transport because of low populations, limited radionuclide uptake, and filtration by the 
rock. However, to conclude that colloids are an unimportant factor for repository safety 
would require information from larger-scale natural studies in relevant geological 
environments, which would allow study of the efficacy of buffering reactions for Eh 
and pH and evidence for long-distance (km-scale) transport in relevant geologic 
formations. 
Transport in Unsaturated Ash Flow Tuffs: Pea Blanca is probably the closest overall 
analogue with conditions similar to Yucca Mountain. Nopal I is a natural environment 
where groundwater chemistry is somewhat analogous to groundwaters in the Yucca 
Mountain system, and groundwaters contain elevated concentrations of radionuclides 
and other trace elements from a known source. Nopal I also displays discrete zones in 
fractured rocks intersected by potentially identifiable preferential groundwater flow 
paths. Such flow paths would allow definition of a source region and transport 
pathway, as well as a study of sorption processes on fracture surface minerals. 

Table 15-1. Natural Analogues in This Report and Their 
Potential Applications to Performance Assessment 
Section in 
Natural 
Analogue 
Report 
Conceptual Model Development 
(Applied Processes from 
Natural Analogues) 
Use of Specific 
Parameters in Yucca 
Mountain TSPA Model 
Use for Model Validation of 
Yucca Mountain 
Characterization 
3.2 
Dimensions of caves and 
underground openings that have 
stood open for thousands of years 
3.3 
Man-made openings have stood 
open for thousands of years 
(oldest 4000 B.C.) 
3.5 
Variables that determine 
structural stability of underground 
openings 
4.2, 4.4 
Nopal I validated spent fuel 
dissolution experiments where Usilicates 
are long-term solubilitylimiting 
phases 
4.3 
Retention of fission products at 
Oklo related to partitioning into 
uraninite 
4.4 
Importance of secondary phases 
at Shinkolobwe and Oklobondo 
in retaining U 
4.6 
Chemical and physical conditions 
required to reach criticality at Oklo 
used to estimate amount of spent 
fuel needed to create critical 
conditions at a repository 
4.7 
Qualitative validation that natural 
glass alteration studies indicate 
nuclear waste glass will be stable 
in a repository environment 
6.2 
Enhanced preservation of objects 
stored in unsaturated conditions, 
as observed in Pintwater cave 
(NV) 
6.2 
Vapor condensation resulting in 
corrosion, as observed in Altamira 
cave (Spain) 
6.2 
Effects of hypersaline fluids on 
waste package materials, as 
observed in corrosion behavior of 
different metal compositions at 
Salton Sea (CA) geothermal field 
Evaporation 
experiments conducted 
to determine evolution 
of Yucca Mountain 
water compositions and 
corresponding mineral 
precipitate 

Table 15-1 (Continued). Natural Analogues in This Report and Their 
Potential Applications to Performance Assessment 
Section in 
Natural 
Analogue 
Report 
Conceptual Model Development 
(Applied Processes from 
Natural Analogues) 
Use of Specific 
Parameters in Yucca 
Mountain TSPA Model 
Use for Model Validation of 
Yucca Mountain 
Characterization 
6.2 
Formation of protective passive 
film around metals, as observed in 
Delhi iron pillar (India) 
6.2 
Long-term stability of Ni-Fe 
metals, as evidenced by 
occurrence of josephinite in 150 
million year old ultramafic rocks 
(OR) 
7.2 
Effects of hypersaline fluids on 
titanium, as observed in corrosion 
behavior of titanium alloys at 
Salton Sea (CA) geothermal field 
7.2 
Effects of zeolites and clay 
minerals on ion exchange and 
sorption of radionuclides, as 
observed in tuffs at Yucca 
Mountain and Los Alamos, NM 
7.3 
Development of hyperalkaline 
plumes from cementitious 
materials, as observed at Maqarin 
(Jordan) 
Multicomponent reactive transport 
model used to compare simulated 
and observed fluid chemistry and 
rock alteration mineralogy at 
Maqarin (Jordan) 
7.3 
Fe-bearing colloids may retard U 
and other spent fuel components 
by forming colloids that are filtered 
from suspension at short 
distances, Poos de Caldas, 
Brazil 
8.2 
Analogue studies prediction that 
most infiltration does not become 
seepage as observed at Kartchner 
Caverns, Arizona, and Altamira 
Cave in Spain 
8.3 
Qualitative evidence of flow 
diversion around openings in the 
unsaturated zone independent of 
climate demonstrated by cave 
paintings in southern Europe, 
Egyptian tombs, Buddhist temples 
8.3 
Decreases in seepage with 
decrease in infiltration 
demonstrated by preservation of 
fragile human artifacts and 
organic materials over thousands 
of years 

Table 15-1 (Continued). Natural Analogues in This Report and Their 
Potential Applications to Performance Assessment 
Section in 
Natural 
Analogue 
Report 
Conceptual Model Development 
(Applied Processes from 
Natural Analogues) 
Use of Specific 
Parameters in Yucca 
Mountain TSPA Model 
Use for Model Validation of 
Yucca Mountain 
Characterization 
9.3 
Calibration using ITOUGH2 to 
hydrographs at LPIT yielded 
parameters consistent with 
measured data 
9.3 
Dual-permeability model 
adequately captured flow but not 
transport 
10.4 
Significant dissolution of U may 
have occurred in groundwaters 
near Nopal I; also higher 
dissolution (or more U 
concentration) during dry season 
10.5 
Colloidal transport of U, Th in 
oxidizing UZ at Steenkampskraal 
and Koongarra (little at 
Koongarra) 
11.2 
Fluid flow in fractures, as seen in 
Dixie Valley (USA), Silangkitang 
(Indonesia) and Wairakei (NZ) 
geothermal fields 
11.2 
Numerical simulation of heat and 
fluid flow in numerous developed 
geothermal systems 
Confirmation of TOUGH2-based 
thermal-hydrological reservoir 
simulations through post-audit 
history matching of Olkaria 
(Kenya) and Nesjavellir (Iceland) 
geothermal fields 
11.2 
Use of chemical tracers to 
constrain source of fluids, track 
movement of fluids, and identify 
high-permeability flow paths, as 
conducted at Bulalo (Philippines) 
geothermal field 
11.2, 11.3 
Changes in water chemistry, 
precipitation of silica and calcite, 
and reductions in porosity and 
permeability resulting from boiling, 
as observed at Waiotapu (NZ), 
Cerro Prieto (Mexico), and 
Yellowstone (WY) geothermal 
fields 
11.2 
Precipitation of salts and silica 
associated with dryout, as 
observed in Karaha-Telaga Bodas 
(Indonesia) geothermal field 

Table 15-1 (Continued). Natural Analogues in This Report and Their 
Potential Applications to Performance Assessment 
Section in 
Natural 
Analogue 
Report 
Conceptual Model Development 
(Applied Processes from 
Natural Analogues) 
Use of Specific 
Parameters in Yucca 
Mountain TSPA Model 
Use for Model Validation of 
Yucca Mountain 
Characterization 
11.2 
Mineral dissolution associated 
with condensation, as observed at 
The Geysers (CA) geothermal 
field 
11.2, 11.3 
Reduction in porosity and 
permeability due to silica 
precipitation, as observed at the 
Dunes (CA) and Yellowstone 
(WY) geothermal fields, and in 
reinjection wells at Otake (Japan), 
Rotokawa, Ohaaki, and Wairakei 
(NZ) geothermal fields 
11.2, 11.3 
Use of thermodynamic models to 
predict fluid-mineral reactions at 
reservoir conditions 
Model validation performed 
comparing observed and 
simulated mineral assemblages 
calculated using EQ3/6 codes, 
measured geothermal fluid 
compositions, and observed 
reservoir conditions at 
Yellowstone (WY) and Wairakei 
(NZ) geothermal fields 
11.4 
Modeled possibility of forming 
opal-filled veins with source of 
silica derived from host rock at 
Paiute Ridge 
11.5 
Localized U mobility in tuff at 
temperatures comparable to 
repository 
12.3 
UMTRA plumes  weak to no 
uranium retardation in examples 
studied 
12.4 
Various sites in UZ  some portion 
of U, Th, and REE transported as 
colloids 
13.4 
Resuspension of radionuclides in 
dust particles increases by an 
order of magnitude after soil 
tillage 
13.4 
Environmental -life of 
137Cs in food 0.422 yrs 
(shorter than predicted) 

Table 15-1 (Continued). Natural Analogues in This Report and Their 
Potential Applications to Performance Assessment 
Section in 
Natural 
Analogue 
Report 
Conceptual Model Development 
(Applied Processes from 
Natural Analogues) 
Use of Specific 
Parameters in Yucca 
Mountain TSPA Model 
Use for Model Validation of 
Yucca Mountain 
Characterization 
13.4 
Neglecting soil erosion as means 
of radionuclide removal 
increases model conservatism 
13.4 
Chernobyl  irrigation with 
contaminated water causes 
radionuclide buildup factor 
13.4 
Chernobyl showed that ingestion 
pathway constitutes small part of 
total dose; external pathway 
predominates, except for 
agricultural workers 
14.3 
Intrusion/extrusion ratio 
near 1 supported by 
Paiute Ridge field 
studies and 
reexamination of dike 
systems at San Rafael 
volcanic field 
14.3 
Eruptive style and 
magmatic composition 
with combination of 
scoria cone, spatter 
cones and lava cones 
on the surface, and one 
or more dikes in the 
subsurface based on 
Lathrop Wells volcano 
14.3 
Cerro Negro, in Nicaragua, used 
to validate the ASHPLUME 
codes ability to simulate an 
eruption 
14.4 
Enhanced ability of underground 
structures to withstand damage 
from earthquakes demonstrated 
by lack of damage in underground 
facilities during major earthquakes 
14.4 
The DRKBA code used to model 
rockfall probabilities using quasistatic 
method of reducing the 
joint strength parameters to 
account for the seismic effect 
was verified based on the test 
runs using the dynamic functions 
of the distinct element code 
UDEC. 
Source: Simmons 2002 [157578], YMP-LBNL-AMS-NA-2, pp. 11-14. 

Source: IAEA 1999 [157485], Figure 1. 
Figure 15-1. The Role of Natural Analogues and Site Characterization in Performance Assessment 

16. INPUTS AND REFERENCES 
The following is a list of the references cited in this document. Column 1 represents the unique 
six digit numerical identifier, which is placed in the text following the reference callout (e.g., 
CRWMS M&O 2000 [151615]). The purpose of these numbers is to assist the reader in locating 
a specific reference. Within the reference list, multiple sources by the same author (e.g., 
CRWMS M&O 2000) are sorted alphabetically by title. 
16.1 CITED DOCUMENTS 
156348 Adams, M.C.; Benoit, W.R.; Doughty, C.; Bodvarsson, G.S.; and Moore, J.N. 1989. 
The Dixie Valley, Nevada Tracer Test. Geothermal Resources Council 
Transactions, 13, 215220. Davis, California: Geothermal Resources Council. TIC: 
250751. 
104751 Ahn, T.M. and Soo, P. 1995. Corrosion of Low-Carbon Cast Steel in Concentrated 
Synthetic Groundwater at 80 to 150C. Waste Management, 15, (7), 471476. New 
York, New York: Elsevier. TIC: 236890. 
156316 Allis, R. and Moore, J.N. 2000. Evolution of Volcano-Hosted Vapor-Dominated 
Geothermal Systems. Geothermal Resources Council Transactions, 24, 211216. 
Davis, California: Geothermal Resources Council. TIC: 250762. 
156317 Allis, R.; Moore, J.N.; McCulloch, J.; Petty, S.; and DeRocher, T. 2000. Karaha- 
Telaga Bodas, Indonesia: A Partially Vapor-Dominated Geothermal System. 
Geothermal Resources Council Transactions, 24, 217222. Davis, California: 
Geothermal Resources Council. TIC: 250767. 
156425 Appelo, C.A.J. 1996. Multicomponent Ion Exchange and Chromatography in 
Natural Systems. Chapter 4 of Reactive Transport in Porous Media. Lichtner, P.C.; 
Steefel, C.I.; and Oelkers, E.H., eds. Reviews in Mineralogy Volume 34. 
Washington, D.C.: Mineralogical Society of America. TIC: 236866. 
154615 Apps, J.A. 1995. Natural Geochemical Analogues of the Near Field of High-Level 
Nuclear Waste Repositories. Proceedings of the Workshop on the Role of Natural 
Analogs in Geologic Disposal of High-Level Nuclear Waste, San Antonio, Texas, July 
2225, 1991. Kovach, L.A. and Murphy, W.M., eds. NUREG/CP-0147. Pages 75 
99. Washington, D.C.: U.S. Nuclear Regulatory Commission. TIC: 225202. 
123814 Arai, T.; Yusa, Y.; Sasaki, N.; Tsunoda, N.; and Takano, H. 1989. Natural 
Analogue Study of Volcanic GlassA Case Study of Basaltic Glasses in Pyroclastic 
Fall Deposits of Fuji Volcano, Japan. Scientific Basis for Nuclear Waste 
Management XII, Symposium held October 1013, 1988, Berlin, Germany. Lutze, 
W. and Ewing, R.C., eds. 127, 7380. Pittsburgh, Pennsylvania: Materials Research 
Society. TIC: 203660. 

168020 Ariceaga-Martinez, C.A. 2003. Drilling and Instrumentation of Three Piezometers, 
UACH Project, El Nopal Deposit, Wells: PB-1, PB-2, and PB-3, Final Report. 
Chihuahua, Mexico: Federal Commission of Electricity. ACC: 
MOL.200401008.0361. 
156321 Arnrsson, S. 1995. Geothermal Systems in Iceland: Structure and Conceptual 
ModelsI. High-Temperature Areas. Geothermics, 24, (5/6), 561602. [New 
York, New York]: Pergamon Press. TIC: 250772. 
157383 Balasubramaniam, R. 2000. On the Corrosion Resistance of the Delhi Iron Pillar. 
Corrosion Science, 42, (12), 21032129. [New York, New York]: Elsevier. TIC: 
251551. 
103949 Bandurraga, T.M. and Bodvarsson, G.S. 1999. Calibrating Hydrogeologic 
Parameters for the 3-D Site-Scale Unsaturated Zone Model of Yucca Mountain, 
Nevada. Journal of Contaminant Hydrology, 38, (13), 2546. New York, New 
York: Elsevier. TIC: 244160. 
157505 Bar'yakhtar, V.; Poyarkov, V.; Kholosha, V.; and Kuckhar', V. 2000. The Shelter, 
Containing the Destroyed Reactor. Chapter 3 of The Chornobyl Accident, A 
Comprehensive Risk Assessment. Vargo, G.J., ed. Columbus, Ohio: Battelle Press. 
TIC: 251266. 
157504 Bar'yakhtar, V.; Poyarkov, V.; Kholosha, V.; and Shteinberg, N. 2000. The 
Accident, Chronology, Causes, and Releases. Chapter 2 of The Chornobyl Accident, 
A Comprehensive Risk Assessment. Vargo, G.J., ed. Columbus, Ohio: Battelle Press. 
TIC: 251266. 
157419 Bar-Yosef, O.; Arnold, M.; Mercier, N.; Belfer-Cohen, A.; Goldberg, P.; Housley, R.; 
Laville, H.; Meignen, L.; Vogel, J.C.; and Vandermeersch, B. 1996. The Dating of 
the Upper Paleolithic Layers in Kebara Cave, Mt Carmel. Journal of 
Archaeological Science, 23, 297306. New York, New York: Academic Press 
Limited. TIC: 251573. 
156255 Barenblatt, G.I.; Zheltov, I.P.; and Kochina, I.N. 1960. Basic Concepts in the 
Theory of Seepage of Homogeneous Liquids in Fissured Rocks [Strata]. Journal of 
Applied Mathmatics, 24, (5), 12861303. New York, New York: Pergamon Press. 
TIC: 216852. 
156241 Bargar, K.E. and Beeson, M.H. 1984. Hydrothermal Alteration in Research Drill 
Hole Y6, Upper Firehole River, Yellowstone National Park, Wyoming. U.S. 
Geological Survey Professional Paper 1054-B. Washington, D.C.: U.S. Govenment 
Printing Office. ACC: HQS.19880517.1948. 
156243 Bargar, K.E. and Beeson, M.H. 1985. Hydrothermal Alteration in Research Drill 
Hole Y-3, Lower Geyser Basin, Yellowstone National Park, Wyoming. U.S. 
Geological Survey Professional Paper 1054-C. Washington, D.C.: U.S. Government 
Printing Office. TIC: 230761. 

156244 Bargar, K.E.; Beeson, M.H.; and Keith, T.E.C. 1981. Zeolites in Yellowstone 
National Park. The Mineralogical Record, 12, 2938. Tucson, Arizona: 
Mineralogical Record. TIC: 250820. 
156426 Barraclough, J.T.; Robertson, J.B.; Janzer, V.J.; and Saindon, L.G. 1976. Hydrology 
of the Solid Waste Burial Ground as Related to the Potential Migration of 
Radionuclides, Idaho National Engineering Laboratory. Open-File Report 76-471. 
Idaho Falls, Idaho: U.S. Geological Survey. TIC: 251803. 
156445 Barth-Wirsching, U. and Hller, H. 1989. Experimental Studies on Zeolite 
Formation Conditions. European Journal of Mineralogy, 1, 489506. Stuttgart, 
Germany: E. Schweizerbartsche Verlagsbuchhandlung. TIC: 250916. 
156953 Baryakhtar, V.G. 1997. Chernobyl Catastrophe. New York, New York: Begell 
House. TIC: 251556. 
157531 Bassett, W.A.; Bird, J.M.; Weathers, M.S.; and Kohlstedt, D.L. 1980. Josephinite: 
Crystal Structures and Phase Relations of the Metals. Physics of the Earth and 
Planetary Interiors, 23, 255261. Amsterdam, The Netherlands: Elsevier. TIC. 
251814. 
157407 Becker, B.H.; Burgess, J.D.; Holdren, K.J.; Jorgensen, D.K.; Magnuson, S.O.; and 
Sondrup, A.J. 1998. Interim Risk Assessment and Contaminant Screening for the 
Waste Area Group 7 Remedial Investigation. DOE/ID-10569. Idaho Falls, Idaho: 
U.S. Department of Energy, Idaho Operations Office. TIC: 251834. 156213 Behl, 
B.K. 1998. The Ajanta Caves, Artistic Wonder of Ancient Buddhist India. New 
York, New York: Harry N. Abrams. TIC: 250802. 
156213 Behl, B.K. 1998. The Ajanta Caves, Artistic Wonder of Ancient Buddhist India. 
New York, New York: Harry N. Abrams. TIC: 250802. 
101036 Benson, L.V. and McKinley, P.W. 1985. Chemical Composition of Ground Water in 
the Yucca Mountain Area, Nevada, 1971-84. Open-File Report 85-484. Denver, 
Colorado: U.S. Geological Survey. ACC: NNA.19900207.0281. 
100727 Benson, L.V.; Robison, J.H.; Blankennagel, R.K.; and Ogard, A.E. 1983. Chemical 
Composition of Ground Water and the Locations of Permeable Zones in the Yucca 
Mountain Area, Nevada. Open-File Report 83-854. Denver, Colorado: U.S. 
Geological Survey. ACC: NNA.19870610.0028. 
156592 Berkovski, V.; Ratia, G.; and Nasvit, O. 1996. Internal Doses to Ukrainian 
Populations Using Dnieper River Water. Health Physics, 71, (1), 3744. New 
York, New York: Pergamon. TIC: 250875. 
154601 Bird, D.K. and Elders, W.A. 1976. Hydrothermal Alteration and Mass Transfer in 
the Discharge Portion of the Dunes Geothermal System, Imperial Valley of 
California, USA. Proceedings of the Second United Nations Symposium on the 
Development and Use of Geothermal Resources, San Francisco, California, USA, 

2029 May 1975. 1, 285295. Washington, D.C.: U.S. Government Printing Office. 
TIC: 249829. 
157514 Bird, J.M. 2001. John M. Bird. Ithaca, New York: Cornell University. Accessed 
January 30, 2002. TIC: 251749. 
http://www.geo.cornell.edu/geology/faculty/Bird.html 
157397 Bird, J.M. and Ringwood, A.E. 1980. Container for Radioactive Nuclear Waste 
Materials. U.S. Patent Number: 4,192,765. Washington, D.C.: U.S. Patent Office. 
TIC: 251651. 
157398 Bird, J.M. and Ringwood, A.E. 1982. Container for Radioactive Nuclear Waste 
Materials. U.S. Patent Number: 4,337,167. Washington, D.C.: U.S. Patent Office. 
TIC: 251653. 
157396 Bird, J.M. and Ringwood, A.E. 1984. Container for Radioactive Nuclear Waste 
Materials. U.S. Patent Number: 4,474,689. Washington, D.C.: U.S. Patent Office. 
TIC: 251649. 
105170 Birkholzer, J.; Li, G.; Tsang, C-F.; and Tsang, Y. 1999. Modeling Studies and 
Analysis of Seepage into Drifts at Yucca Mountain. Journal of Contaminant 
Hydrology, 38, (13), 349384. New York, New York: Elsevier. TIC: 244160. 
100006 Bish, D.L. and Aronson, J.L. 1993. Paleogeothermal and Paleohydrologic 
Conditions in Silicic Tuff from Yucca Mountain, Nevada. Clays and Clay Minerals, 
41, (2), 148161. Long Island City, New York: Pergamon Press. TIC: 224613. 
101195 Bish, D.L. and Chipera, S.J. 1989. Revised Mineralogic Summary of Yucca 
Mountain, Nevada. LA-11497-MS. Los Alamos, New Mexico: Los Alamos 
National Laboratory. ACC: NNA.19891019.0029. 
157498 Blanc, P.-L. 1996. Acquirements of the Project. Volume 1 of OkloNatural 
Analogue for a Radioactive Waste Repository (Phase 1). EUR 16857/1 EN. 
Luxembourg, Luxembourg: Commission of the European Communities. TIC: 
251893. 
124640 Blomqvist, R.; Suksi, J.; Ruskeeniemi, T.; Ahonen, L.; Niini, H.; Vuorinen, U.; and 
Jakobsson, K. 1995. The Palmottu Natural Analogue Project, Summary Report 
19921994, The Behaviour of Natural Radionuclides in and Around Uranium 
Deposits; Nr. 8. YST-88. Espoo, Finland: Geological Survey of Finland. TIC: 
247142. 
156337 Bodvarsson, G.S. and Witherspoon, P.A. 1989. Geothermal Reservoir Engineering 
Part 1. Geothermal Science and Technology, 2, (1), 168. New York, New York: 
Gordon and Breach Science Publishers. TIC: 250976. 
120055 Bodvarsson, G.S.; Boyle, W.; Patterson, R.; and Williams, D. 1999. Overview of 
Scientific Investigations at Yucca MountainThe Potential Repository for High

Level Nuclear Waste. Journal of Contaminant Hydrology, 38, (1-3), 3-24. New 
York, New York: Elsevier. TIC: 244160. 
138618 Bodvarsson, G.S.; Gislason, G.; Gunnlaugsson, E.; Sigurdsson, O.; Stefansson, V.; 
and Steingrimsson, B. 1993. Accuracy of Reservoir Predictions for the Nesjavellir 
Geothermal Field, Iceland. Proceedings, Eighteenth Workshop, Geothermal 
Reservoir Engineering, Stanford, California, January 2628, 1993. Ramey, H.J., Jr.; 
Horne, R.N.; Kruger, P.; Miller, F.G.; Brigham, W.E.; and Cook, J.W., eds. 
Workshop Report SGP-TR-145. Pages 273278. Stanford, California: Stanford 
University. TIC: 246821. 
136384 Bodvarsson, G.S.; Pruess, K.; Haukwa, C.; and Ojiambo, S.B. 1990. Evaluation of 
Reservoir Model Predictions for Olkaria East Geothermal Field, Kenya. 
Geothermics, 19, (5), 399414. New York, New York: Pergamon Press. TIC: 
246739. 
156363 Bohlmann, E.G.; Mesmer, R.E.; and Berlinski, P. 1980. Kinetics of Silica 
Deposition From Simulated Geothermal Brines. Society of Petroleum Engineers 
Journal, 20, (4), 239248. Dallas, Texas: Society of Petroleum Engineers. TIC: 
250974. 
156635 Boles, J.R. 1999. Calcite Precipitates in the Mission Tunnel: A 90-Year Record of 
Groundwater Seeps in Fractured Sandstone. Eos, Transactions (Supplement), 80, 
(46), F423. Washington, D.C.: American Geophysical Union. TIC: 251227. 
156593 Bondarenko, O.A.; Aryasov, B.B.; and Tsygankov, N.Ya. 2000. Evaluation of the 
Plutonium Content in the Human Body Due to Global and Chernobyl Fallout. 
Journal of Radioanalytical and Nuclear Chemistry, 243, (2), 473478. Dordrecht, 
The Netherlands: Kluwer Academic Publishers. TIC: 251062. 
154716 Botto, R.I. and Morrison, G.H. 1976. Josephinite: A Unique Nickel-Iron. 
American Journal of Science, 276, (3), 241274. New Haven, Connecticut: Yale 
University, Kline Geology Laboratory. TIC: 249797. 
156456 Breisch, R.L. 1987. The Conservation of European Cave Art. NSS News, 45, 
285291. Huntsville, Alabama: National Speleological Society. TIC: 251229. 
133930 Brookins, D.G. 1978. Retention of Transuranic and Actinide Elements and Bismuth 
at the Oklo Natural Reactor, Gabon: Application of EhpH Diagrams. Chemical 
Geology, 23, 309-323. Amsterdam, The Netherlands: Elsevier. TIC: 247321. 
109877 Brookins, D.G. 1986. Natural Analogues for Radwaste Disposal: Elemental 
Migration in Igneous Contact Zones. Chemical Geology, 55, 337344. Amsterdam, 
The Netherlands: Elsevier. TIC: 246170. 
102004 Broxton, D.E.; Bish, D.L.; and Warren, R.G. 1987. Distribution and Chemistry of 
Diagenetic Minerals at Yucca Mountain, Nye County, Nevada. Clays and Clay 

Minerals, 35, (2), 89110. Long Island City, New York: Pergamon Press. TIC: 
203900. 
100024 Broxton, D.E.; Warren, R.G.; Byers, F.M.; and Scott, R.B. 1989. Chemical and 
Mineralogic Trends Within the Timber MountainOasis Valley Caldera Complex, 
Nevada: Evidence for Multiple Cycles of Chemical Evolution in a Long-Lived Silicic 
Magma System. Journal of Geophysical Research, 94, (B5), 59615985. 
Washington, D.C.: American Geophysical Union. TIC: 225928. 
156600 Bruk, G.Y.; Shutov, V.N.; Balonov, M.I.; Basalayeva, L.N.; and Kislov, M.V. 1998. 
Dynamics of 137Cs Content in Agricultural Food Products Produced in Regions of 
Russia Contaminated after the Chernobyl Accident. Radiation Protection 
Dosimetry, 76, (3), 169178. Ashford, Kent, United Kingdom: Nuclear Technology 
Publishing. TIC: 251136. 
157484 Bruno, J.; Duro, L.; and Griv, M. 2001. The Applicability and Limitations of the 
Geochemical Models and Tools Used in Simulating Radionuclide Behaviour in 
Natural Waters, Lessons Learned from the Blind Predictive Modelling Exercises 
Performed in Conjunction with Natural Analogue Studies. SKB TR-01-20. 
Stockholm, Sweden: Svensk Krnbrnslefrsrjning A.B. TIC: 251208. 
100105 Bruton, C.J. 1995. Testing EQ3/6 and GEMBOCHS Using Fluid-Mineral Equilibria 
in the Wairakei Geothermal System. Letter Report MOL206. Livermore, California: 
Lawrence Livermore National Laboratory. ACC: MOL.19960409.0131. 
117033 Bruton, C.J.; Glassley, W.E.; and Meike, A. 1995. Geothermal Areas as Analogues 
to Chemical Processes in the Near-Field and Altered Zone of the Potential Yucca 
Mountain, Nevada Repository. UCRL-ID-119842. Livermore, California: Lawrence 
Livermore National Laboratory. ACC: MOV.19980504.0002. 
156304 BSC (Bechtel SAIC Company). 2001. Drift Degradation Analysis. ANL-EBS-MD- 
000027 REV 01 ICN 01. Las Vegas, Nevada: Bechtel SAIC Company. ACC: 
MOL.20011029.0311. 
154677 BSC (Bechtel SAIC Company) 2001. Drift-Scale Coupled Processes (DST and THC 
Seepage) Models. MDL-NBS-HS-000001 REV 01 ICN 01. Las Vegas, Nevada: 
Bechtel SAIC Company. ACC: MOL.20010418.0010. 
155950 BSC (Bechtel SAIC Company) 2001. FY 01 Supplemental Science and Performance 
Analyses, Volume 1: Scientific Bases and Analyses. TDR-MGR-MD-000007 REV 00 
ICN 01. Las Vegas, Nevada: Bechtel SAIC Company. ACC: MOL.20010801.0404; 
MOL.20010712.0062; MOL.20010815.0001. 
155664 BSC (Bechtel SAIC Company) 2001. Subsurface Facility System Description 
Document. SDD-SFS-SE-000001 REV 01 ICN 01. Las Vegas, Nevada: Bechtel 
SAIC Company. ACC: MOL.20010927.0073. 

157151 BSC (Bechtel SAIC Company) 2001. Technical Update Impact Letter Report. MISMGR-
RL-000001 REV 00 ICN 02. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: MOL.20011211.0311. 
157535 BSC (Bechtel SAIC Company) 2001. Technical Work Plan for Natural Analogue 
Studies for License Application. TWP-NBS-GS-000002 REV 01. Las Vegas, 
Nevada: Bechtel SAIC Company. ACC: MOL.20020213.0181. 
168402 BSC. 2002. Technical Work Plan for Pea Blanca Natural Analogue. TWP-NBSGS-
000002 REV 02. Las Vegas, Nevada: Bechtel SAIC Company. ACC: 
MOL.20030106.0077. 
157606 BSC (Bechtel SAIC Company) 2002. Test Plan for: Alcove 8 Flow and Seepage 
Testing. SITP-02-UZ-003 REV00. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: MOL.20020204.0144. 
161773 BSC (Bechtel SAIC Company) 2003. Analysis of Hydrologic Properties Data. 
MDL-NBS-HS-00014 REV 00. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20030404.0004. 
166407 BSC (Bechtel SAIC Company) 2003. Characterize Eruptive Processes at Yucca 
Mountain, Nevada. ANL-MGR-GS-000002 REV 01. Las Vegas, Nevada: Bechtel 
SAIC Company. ACC: DOC.20031218.0003. 
163769 BSC (Bechtel SAIC Company) 2003. Characterize Framework for Igneous Activity 
at Yucca Mountain, Nevada. ANL-MGR-GS-000001 REV 01. Las Vegas, Nevada: 
Bechtel SAIC Company. ACC: DOC.20040106.0003. 
163958 BSC (Bechtel SAIC Company) 2003. Disruptive Event Biosphere Dose Conversion 
Factor Analysis. ANL-MGR-MD-000003 REV 02. Las Vegas, Nevada: Bechtel 
SAIC Company. ACC: DOC.20030724.0003. 
167974 BSC (Bechtel SAIC Company) 2004. Errata 001 for Drift-Scale Coupled Processes 
(DST and THC Seepage) Models. MDL-NBS-HS-000001 REV 02. Las Vegas, 
Nevada: Bechtel SAIC Company. ACC: DOC.20030804.0004, DOC20040219.0002. 
168845 BSC (Bechtel SAIC Company) 2004. Yucca Mountain Site Description. TDRCRW-
GS-000001 REV 02. Two volumes. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: DOC.20040419.0003. 
157438 Buck, P.E. and DuBarton, A. 1994. Archaeological Investigations at Pintwater 
Cave, Nevada, During the 196364 Field Season. Journal of California and Great 
Basin Anthropology, 16, (2), 221242. Morongo Indian Reservation, Banning, 
California: Malki Museum. TIC: 251661. 
100712 Buddemeier, R.W. and Hunt, J.R. 1988. Transport of Colloidal Contaminants in 
Groundwater: Radionuclide Migration at the Nevada Test Site. Applied 
Geochemistry, 3, 535548. Oxford, England: Pergamon Press. TIC: 224116. 

154295 Buecher, R.H. 1999. Microclimate Study of Kartchner Caverns, Arizona. Journal 
of Cave and Karst Studies, 61, (2), 108120. Huntsville, Alabama: National 
Speleological Society. TIC: 249657. 
156596 Bugai, D.A.; Waters, R.D.; Dzhepo, S.P.; and Skal'skij, A.S. 1996. Risks from 
Radionuclide Migration to Groundwater in the Chernobyl 30-KM Zone. Health 
Physics, 71, (1), 918. New York, New York: Pergamon. TIC: 251063. 
144410 Bullivant, D.P. and O'Sullivan, M.J. 1998. Inverse Modelling of the Wairakei 
Geothermal Field. Proceedings of the TOUGH Workshop '98, Berkeley, California, 
May 46, 1998. Preuss, K., ed. LBNL-41995. Pages 53-58. Berkeley, California: 
Lawrence Berkeley National Laboratory. TIC: 247159. 
156401 Burgess, J.D. 1995. Results of the Neutron and Natural Gamma Logging, 
Stratigraphy, and Perched Water Data Collected during a Large-Scale Infiltration 
Test. INEL-95/212. Idaho Falls, Idaho: Idaho National Engineering Laboratory. 
TIC: 251836. 
121857 Byers, C.D.; Jercinovic, M.J.; and Ewing, R.C. 1987. A Study of Natural Glass 
Analogues as Applied to Alteration of Nuclear Waste Glass. NUREG/CR-4842. 
Washington, D.C.: U.S. Nuclear Regulatory Commission. TIC: 231239. 
101859 Byers, F.M., Jr. and Barnes, H. 1967. Geologic Map of the Paiute Ridge Quadrangle, 
Nye and Lincoln Counties, Nevada. Map GQ-577. Washington, D.C.: U.S. 
Geological Survey. ACC: HQS.19880517.1104. 
104639 Byers, F.M., Jr.; Carr, W.J.; Orkild, P.P.; Quinlivan, W.D.; and Sargent, K.A. 1976. 
Volcanic Suites and Related Cauldrons of Timber Mountain-Oasis Valley Caldera 
Complex, Southern Nevada. Professional Paper 919. Washington, D.C.: U.S. 
Geological Survey. TIC: 201146. 
101326 Carlos, B.A.; Chipera, S.J.; and Bish, D.L. 1995. Distribution and Chemistry of 
Fracture-Lining Minerals at Yucca Mountain, Nevada. LA-12977-MS. Los Alamos, 
New Mexico: Los Alamos National Laboratory. ACC: MOL.19960306.0564. 
154504 Carpenter, D.W. and Chung, D.H. 1986. Effects of Earthquakes on Underground 
Facilities: Literature Review and Discussion. NUREG/CR-4609. Washington, D.C.: 
U.S. Nuclear Regulatory Commission. TIC: 203428. 
124275 Carroll, S.; Mroczek, E.; Alai, M.; and Ebert, M. 1998. Amorphous Silica 
Precipitation (60 to 120C): Comparison of Laboratory and Field Rates. 
Geochimica et Cosmochimica Acta, 62, (8), 13791396. New York, New York: 
Elsevier. TIC: 243029. 
109627 Carroll, S.; Mroczek, E.; Bourcier, B.; Alai, M.; and Ebert, M. 1995. Comparison of 
Field and Laboratory Precipitation Rates of Amorphous Silica from Geothermal 
Waters at 100C. Letter Report MOL207. Livermore, California: Lawrence 
Livermore National Laboratory. ACC: MOL.19960415.0465. 

156256 Cecil, L.D.; Pittman, J.R.; Beasley, T.M.; Michel, R.L; Kubik, P.W.; Sharma, P.; Fen, 
U.; and Gove, H.E. 1992. Water Infiltration Rates in the Unsaturated Zone at the 
Idaho National Engineering Laboratory Estimated from Chlorine-36 and Tritium 
Profiles and Neutron Logging. Water-Rock Interaction, Proceedings of the 7th 
International Symposium on Water-Rock InteractionWRI-7, Park City, Utah, 1318 
July 1992. Kharaka, Y.K. and Maest, A.S., eds. 1, 709718. Brookfield, Vermont: 
A.A. Balkema. TIC: 208527. 
157549 Chambers, A.V.; Haworth, A.; Ilett, D.; Linklater, C.M.; and Tweed, C.J. 1998. 
Geochemical Modelling of Hyperalkaline Water/Rock Interactions. Chapter 7 of 
MAQARIN Natural Analogue Study: Phase III, Volume I. Smellie, J.A.T., ed. SKB 
TR-98-04. Stockholm, Sweden: Svensk Krnbrnslefrsrjning A.B. TIC: 244013. 
124323 Chapman, N.A. and Smellie, J.A.T. 1986. Introduction and Summary of the 
Workshop. Chemical Geology, 55, 167173. Amsterdam, The Netherlands: 
Elsevier. TIC: 246750. 
100970 Chapman, N.A.; Andersson, J.; Robinson, P.; Skagius, K.; Wene, C-O.; Wiborgh, M.; 
and Wingefors, S. 1995. Systems Analysis, Scenario Construction and Consequence 
Analysis Definition for SITE-94. SKI Report 95:26. Stockholm, Sweden: Swedish 
Nuclear Power Inspectorate. TIC: 238888. 
152249 Chauvet, J-M.; Deschamps, E.B.; and Hillaire, C. 1996. Dawn of Art: The Chauvet 
Cave. New York, New York: Harry N. Abrams, Inc. TIC: 248775. 
156349 Chigira, M. and Nakata, E. 1996. Geological Influence of Andesite Intrusion on 
Diatomite (Part 2)Physical Property Changes of Diatomite and Self-Sealing 
Mechanism. Energy Technology Data Exchange, 132. Abiko Japan: Central 
Research Institute of Electric Power Industry, Abiko Research Laboratory. TIC: 
250950. 
156364 Chigira, M.; Nakata, E.; and Watanabe, M. 1995. Self-Sealing of Rock-Water 
Systems by Silica Precipitation. Proceedings of the 8th International Symposium on 
Water-Rock Interaction, WRI-8, Vladivostok, Russia, 1519 August 1995. Kharaka, 
Y.K. and Chudeav, O.V., eds. Pages 7377. Rotterdam, The Netherlands: A.A. 
Balkema. TIC: 250782. 
154599 Cho, M.; Liou, J.G.; and Bird, D.K. 1988. Prograde Phase Relations in the State 2- 
14 Well Metasandstones, Salton Sea Geothermal Field, California. Journal of 
Geophysical Research, 93, (B11), 13,08113,103. Washington, D.C.: American 
Geophysical Union. TIC: 249734. 
156739 Christiansen, R.L. 2001. The Quaternary and Pliocene Yellowstone Plateau 
Volcanic Field of Wyoming, Idaho, and Montana. Professional Paper 729-G. Menlo 
Park, California: U.S. Geological Survey. TIC: 251137. 
156780 Clark, J.F. and Turekian, K.K. 1990. Time Scale of Hydrothermal Water-Rock 
Reactions in Yellowstone National Park Based on Radium Isotopes and Radon. 

Journal of Volcanology and Geothermal Research, 40, 169180. Amsterdam, The 
Netherlands: Elsevier. TIC: 251240. 
156636 Corchon, M.S.; Valladas, H.; Becares, J.; Arnold, M.; Tisnerat, N.; and Cachier, H. 
1996. Dating of the Paintings and a Review of the Paleolithic Art of the Palomera 
Cave (Ojo Guarea, Burgos, Spain). Zephyrus, 49, 3760. Salamanca, Spain: 
Universidad de Salamanca. TIC: 251231. 
156344 Corsi, R. 1986. Scaling and Corrosion in Geothermal Equipment: Problems and 
Preventive Measures. Geothermics, 15, (5/6), 839856. New York, New York: 
Pergamon. TIC: 250785. 
124396 Cowan, R. and Ewing, R.C. 1989. Freshwater Alteration of Basaltic Glass, 
Hanauma Bay, Oahu, Hawaii: A Natural Analogue for the Alteration of Borosilicate 
Glass in Freshwater. Scientific Basis for Nuclear Waste Management XII, 
Symposium held October 1013, 1988, Berlin, Germany. Lutze, W. and Ewing, R.C., 
eds. 127, 4956. Pittsburgh, Pennsylvania: Materials Research Society. TIC: 
203660. 
157537 Cramer, J.J. 1994. Natural Analogs in Support of the Canadian Concept for Nuclear 
Fuel Waste Disposal. AECL-10291. Pinawa, Manitoba, Canada: Whiteshell 
Laboratories. TIC: 212296. 
157420 Crawford, H. 1979. Subterranean Britain, Aspects of Underground Archaeology. 
New York, New York: St. Martin's Press. TIC: 251575. 
100972 Crowe, B.; Self, S.; Vaniman, D.; Amos, R.; and Perry, F. 1983. Aspects of 
Potential Magmatic Disruption of a High-Level Radioactive Waste Repository in 
Southern Nevada. Journal of Geology, 91, (3), 259276. Chicago, Illinois: 
University of Chicago Press. TIC: 216959. 
100116 CRWMS M&O 1996. Probabilistic Volcanic Hazard Analysis for Yucca Mountain, 
Nevada. BA0000000-01717-2200-00082 REV 0. Las Vegas, Nevada: CRWMS 
M&O. ACC: MOL.19971201.0221. 
100223 CRWMS M&O 1997. Determination of Available Volume for Repository Siting. 
BCA000000-01717-0200-00007 REV 00. Las Vegas, Nevada: CRWMS M&O. 
ACC: MOL.19971009.0699. 
103731 CRWMS M&O 1998. Probabilistic Seismic Hazard Analyses for Fault 
Displacement and Vibratory Ground Motion at Yucca Mountain, Nevada. Milestone 
SP32IM3, September 23, 1998. Three volumes. Las Vegas, Nevada: CRWMS 
M&O. ACC: MOL.19981207.0393. 
132547 CRWMS M&O 1999. ASHPLUME Version 1.4LV Design Document. 10022-DD- 
1.4LV-00, Rev. 00. Las Vegas, Nevada: CRWMS M&O. ACC: 
MOL.20000424.0415. 

107292 CRWMS M&O 1999. License Application Design Selection Report. B00000000- 
01717-4600-00123 REV 01 ICN 01. Las Vegas, Nevada: CRWMS M&O. ACC: 
MOL.19990908.0319. 
151615 CRWMS M&O 2000. Biosphere Process Model Report. TDR-MGR-MD-000002 
REV 00 ICN 01. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20000620.0341. 
142321 CRWMS M&O 2000. Characterize Framework for Seismicity and Structural 
Deformation at Yucca Mountain, Nevada. ANL-CRW-GS-000003 REV 00. Las 
Vegas, Nevada: CRWMS M&O. ACC: MOL.20000510.0175. 
152998 CRWMS M&O 2000. Comparison of ASHPLUME Model Results to Representative 
Tephra Fall Deposits. CAL-WIS-MD-000011 REV 00. Las Vegas, Nevada: 
CRWMS M&O. ACC: MOL.20001204.0032. 
151954 CRWMS M&O 2000. Effects of Fault Displacement on Emplacement Drifts. ANLEBS-
GE-000004 REV 00 ICN 01. Las Vegas, Nevada: CRWMS M&O. ACC: 
MOL.20000504.0297. 
151953 CRWMS M&O 2000. Fault Displacement Effects on Transport in the Unsaturated 
Zone. ANL-NBS-HS-000020 REV 01. Las Vegas, Nevada: CRWMS M&O. ACC: 
MOL.20001002.0154. 
141407 CRWMS M&O 2000. Natural Analogs for the Unsaturated Zone. ANL-NBS-HS- 
000007 REV 00. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.19990721.0524. 
153246 CRWMS M&O 2000. Total System Performance Assessment for the Site 
Recommendation. TDR-WIS-PA-000001 REV 00 ICN 01. Las Vegas, Nevada: 
CRWMS M&O. ACC: MOL.20001220.0045. 
152435 CRWMS M&O 2000. Transfer Coefficient Analysis. ANL-MGR-MD-000008 REV 
00 ICN 02. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20001016.0005. 
151940 CRWMS M&O 2000. Unsaturated Zone Flow and Transport Model Process Model 
Report. TDR-NBS-HS-000002 REV 00 ICN 02. Las Vegas, Nevada: CRWMS 
M&O. ACC: MOL.20000831.0280. 
151945 CRWMS M&O 2000. Yucca Mountain Site Description. TDR-CRW-GS-000001 
REV 01 ICN 01. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20001003.0111. 
152536 CRWMS M&O 2001. Disruptive Event Biosphere Dose Conversion Factor Analysis. 
ANL-MGR-MD-000003 REV 01. Las Vegas, Nevada: CRWMS M&O. ACC: 
MOL.20010125.0233. 
152517 CRWMS M&O 2001. Evaluate Soil/Radionuclide Removal by Erosion and 
Leaching. ANL-NBS-MD-000009 REV 00 ICN 01. Las Vegas, Nevada: CRWMS 
M&O. ACC: MOL.20010214.0032. 

100438 Curtis, D.; Benjamin, T.; Gancarz, A.; Loss, R.; Rosman, K.; DeLaeter, J.; Delmore, 
J.E.; and Maeck, W.J. 1989. Fission Product Retention in the Oklo Natural Fission 
Reactors. Applied Geochemistry, 4, 4962. New York, New York: Pergamon Press. 
TIC: 237970. 
110987 Curtis, D.; Fabryka-Martin, J.; Dixon, P.; and Cramer, J. 1999. Natures 
Uncommon Elements: Plutonium and Technetium. Geochimica et Cosmochimica 
Acta, 63, (2), 275285. New York, New York: Pergamon. TIC: 246120. 
157497 Curtis, D.B. 1996. Radionuclide Release Rates from Spent Fuel for Performance 
Assessment Modeling. Sixth EC Natural Analogue Working Group Meeting, 
Proceedings of an International Workshop Held in Santa Fe, New Mexico, USA on 
September 1216, 1994. von Maravic, H. and Smellie, J., eds. EUR 16761 EN. 
Pages 145153. Luxembourg, Luxembourg: Commission of the European 
Communities. TIC: 225227. 
124785 Curtis, D.B. and Gancarz, A.J. 1983. Radiolysis in Nature: Evidence from the Oklo 
Natural Reactors. SKB TR-83-10. Stockholm, Sweden: Svensk 
Krnbrnslefrsrjning A.B. TIC: 205938. 
105270 Curtis, D.B.; Fabryka-Martin, J.; Dixon, P.; Aguilar, R.; and Cramer, J. 1994. 
Radionuclide Release Rates from Natural Analogues of Spent Nuclear Fuel. High 
Level Radioactive Waste Management, Proceedings of the Fifth Annual International 
Conference, Las Vegas, Nevada, May 2226, 1994. 4, 22282236. La Grange Park, 
Illinois: American Nuclear Society. TIC: 210984. 
156374 Dalrymple, G.B.; Grove, M.; Lovera, O.M.; Harrison, T.M.; Hulen, J.B.; and 
Lanphere, M.A. 1999. Age and Thermal History of the Geysers Plutonic Complex 
(Felsite Unit), Geysers Geothermal Field, California: A 40Ar/39Ar and U-Pb Study. 
Earth and Planetary Science Letters, 173, 285298. Amsterdam, The Netherlands: 
Elsevier. TIC: 250858. 
157409 Dames & Moore. 1992. Compilation and Summarization of the Subsurface Disposal 
Area Radionuclide Transport Data at the Radioactive Waste Management Complex. 
EGG-ER-10546. Idaho Falls, Idaho: U.S. Department of Energy, Idaho Field Office. 
ACC: MOL.20040120.0161. 
152137 Dansie, A. 1997. Early Holocene Burials in Nevada, Overview of Localities, 
Research and Legal Issues. Nevada Historical Society Quarterly, 40, (1), 4-14. 
Reno, Nevada: Nevada Historical Society. TIC: 248804. 
157421 Davies, O. 1935. Roman Mines in Europe. Oxford, England: Clarendon Press. TIC: 
251576. 
154436 Davis, J.A.; Coston, J.A.; Kent, D.B.; and Fuller, C.C. 1998. Application of the 
Surface Complexation Concept to Complex Mineral Assemblages. Environmental 
Science & Technology, 32, (19), 28202828. Washington, D.C.: American Chemical 
Society. TIC: 249656. 

144461 Davis, O.K. 1990. Caves as Sources of Biotic Remains in Arid Western North 
America. Palaeogeography, Palaeoclimatology, Palaeoecology, 76, (3/4), 331348. 
Amsterdam, The Netherlands: Elsevier. TIC: 247413. 
101557 Day, W.C.; Potter, C.J.; Sweetkind, D.S.; Dickerson, R.P.; and San Juan, C.A. 1998. 
Bedrock Geologic Map of the Central Block Area, Yucca Mountain, Nye County, 
Nevada. Miscellaneous Investigations Series Map I-2601. Washington, D.C.: U.S. 
Geological Survey. ACC: MOL.19980611.0339. 
157473 De la Cruz, B.; Hernn, P.; and Astudillo, J. 1997. The El Berrocal Project. 
Seventh EC Natural Analogue Working Group Meeting, Proceedings of an 
International Workshop Held in Stein am Rhein, Switzerland from 28 to 30 October 
1996. von Maravic, H. and Smellie, J., eds. EUR 17851 EN. Pages 79103. 
Luxembourg, Luxembourg: Commission of the European Communities. TIC: 
247461. 
101128 Degueldre, C.A. 1994. Colloid Properties in Groundwaters from Crystalline 
Formations. PSI Bericht Nr. 94-21. Villigen, Switzerland: Paul Scherrer Institut. 
TIC: 224100. 
154749 Dick, H.J.B. 1974. Terrestrial Nickel-Iron from the Josephine Peridotite, Its 
Geologic Occurrence, Associations, and Origin. Earth and Planetary Science 
Letters, 24, (2), 291298. Amsterdam, The Netherlands: North-Holland. TIC: 
249849. 
157410 Dicke, C.A. 1997. Distribution Coefficients and Contaminant Solubilities for the 
Waste Area Group 7 Baseline Risk Assessment. INEL/EXT-97-00201. Idaho Falls, 
Idaho: Idaho National Engineering and Environmental Laboratory. TIC: 251838. 
154503 Dobson, P.; Hulen, J.; Kneafsey, T.J.; and Simmons, A. 2001. Permeability at 
Yellowstone: A Natural Analog for Yucca Mountain Processes. Back to the 
FutureManaging the Back End of the Nuclear Fuel Cycle to Create a More Secure 
Energy Future, Proceedings of the 9th International High-Level Radioactive Waste 
Management Conference (IHLRWM), Las Vegas, Nevada, April 29May 3, 2001. La 
Grange Park, Illinois: American Nuclear Society. TIC: 247873. 
154547 Dobson, P.; Hulen, J.; Kneafsey, T.J.; and Simmons, A. 2001. The Role of 
Lithology and Alteration on Permeability and Fluid Flow in the Yellowstone 
Geothermal System, Wyoming. Proceedings, Twenty-Sixth Workshop on 
Geothermal Reservoir Engineering, Palo Alto, California, January 2931, 2001. 
Workshop Report SGP-TR-168. Stanford, California: Stanford University. TIC: 
249825. 
168270 Dobson, P.F.; Kneafsey, T.J.; Hulen, J.; and Simmons, A. 2003. Porosity, 
Permeability, and Fluid Flow in the Yellowstone Geothermal System, Wyoming. 
Journal of Volcanology and Geothermal Research, 123, (34), 313324. New York, 
New York: Elsevier. TIC: 255737. 

165949 Dobson, P.F.; Kneafsey, T.J.; Sonnenthal, E.L.; Spycher, N.; and Apps, J.A. 2003. 
Experimental and Numerical Simulation of Dissolution and Precipitation: 
Implications for Fracture Sealing at Yucca Mountain, Nevada. Journal of 
Contaminant Hydrology, 6263, 459476. New York, New York: Elsevier. TIC: 
254205. 
168273 Dobson, P.F.; Salah, S.; Spycher, N; and Sonnenthal, E. 2003. Simulation of 
Water-Rock Interaction in the Yellowstone Geothermal System Using 
TOUGHREACT. TOUGH Symposium 2003, May1214, 2003, Lawrence Berkeley 
National Laboratory, Berkeley, CA. Berkeley, California: Lawrence Berkeley 
National Laboratory. ACC: QC. 
154692 DOE (U.S. Department of Energy). 1992. Groundwater Hydrology Report. 
Attachment 3 of Remedial Action Plan and Site Design for Stabilization of the 
Inactive Uranium Mill Tailings Site at Gunnison, Colorado. Final. UMTRADOE/
AL-050508.0000. Albuquerque, New Mexico: U.S. Department of Energy, 
UMTRA Project Office. TIC: 250151. 
104736 DOE (U.S. Department of Energy) 1994. Radiological Control Manual. 
MSS/DOE/RP/001, Rev. 1. Washington, D.C.: U.S. Department of Energy. ACC: 
MOL.19950130.0075. 
124789 DOE (U.S. Department of Energy) 1995. Applications of Natural Analogue Studies 
to Yucca Mountain as a Potential High Level Radioactive Waste Repository. 
DOE/YMSCO-002. Washington, D.C.: U.S. Department of Energy, Office of 
Civilian Radioactive Waste Management. ACC: MOL.19980928.0280. 
154693 DOE (U.S. Department of Energy) 1996. Final Programmatic Environmental Impact 
Statement for the Uranium Mill Tailings Remedial Action Ground Water Project. 
DOE/EIS-0198. Two volumes. Grand Junction, Colorado: U.S. Department of 
Energy, Grand Junction Project Office. TIC: 249817. 
100548 DOE (U.S. Department of Energy) 1998. Introduction and Site Characteristics. 
Volume 1 of Viability Assessment of a Repository at Yucca Mountain. DOE/RW- 
0508. Washington, D.C.: U.S. Department of Energy, Office of Civilian Radioactive 
Waste Management. ACC: MOL.19981007.0028. 
154687 DOE (U.S. Department of Energy) 1999. Final Site Observational Work Plan for the 
UMTRA Project New Rifle Site. GJO-99-112-TAR, Rev. 1. Grand Junction, 
Colorado: U.S. Department of Energy, Grand Junction Office. TIC: 249902. 
157603 DOE (U.S. Department of Energy) 2000. UMTRA Ground Water Project Sites. 
Grand Junction, Colorado: U.S. Department of Energy, Grand Junction Office. 
Accessed February 13, 2002. TIC: 251850. 
http://www.doegjpo.com/ugw/sites/sites.htm 
156666 DOE (U.S. Department of Energy) 2001. Final Site Observational Work Plan for 
the Gunnison, Colorado, UMTRA Project Site. GJO-2001-214-TAR. Grand 

Junction, Colorado: U.S. Department of Energy, Grand Junction Office. TIC: 
251120. 
153849 DOE (U.S. Department of Energy) 2001. Yucca Mountain Science and Engineering 
Report. DOE/RW-0539. Washington, D.C.: U.S. Department of Energy, Office of 
Civilian Radioactive Waste Management. ACC: MOL.20010524.0272. 
155970 DOE (U.S. Department of Energy) 2002. Final Environmental Impact Statement for 
a Geologic Repository for the Disposal of Spent Nuclear Fuel and High-Level 
Radioactive Waste at Yucca Mountain, Nye County, Nevada. DOE/EIS-0250. 
Washington, D.C.: U.S. Department of Energy, Office of Civilian Radioactive Waste 
Management. ACC: MOL.20020524.0314; through; MOL.20020524.0320. 
162903 DOE (U.S. Department of Energy) 2003. Quality Assurance Requirements and 
Description. DOE/RW-0333P, Rev. 13. Washington, D.C.: U.S. Department of 
Energy, Office of Civilian Radioactive Waste Management. ACC: 
DOC.20030422.0003. 
156446 Drellack, S.L., Jr. and Thompson, P.H. 1990. Selected Stratigraphic Data for Drill 
Holes in LANL Use Areas of Yucca Flat, NTS. DOE/NV/10322-39. Las Vegas, 
Nevada: U.S. Department of Energy, Nevada Operations Office. TIC: 205994. 
156447 Drury, M.J. 1987. Thermal-Diffusivity of Some Crystalline Rocks. Geothermics, 
16, (2), 105115. New York, New York: Pergamon Press. TIC: 251764 
156402 Dunnivant, F.M.; Newman, M.E.; Bishop, C.W.; Burgess, D.; Giles, J.R.; Higgs, 
B.D.; Hubbell, J.M.; Neher, E.; Norrell, G.T.; Pfiefer, M.C.; Porro, I.; Starr, R.C.; and 
Wylie, A.H. 1998. Water and Radioactive Tracer Flow in a Heterogeneous Field- 
Scale System. Ground Water, 36, (6), 949958. Westerville, Ohio: Ground Water 
Publishing Company. TIC: 250984. 
157493 Eckel, E.B. 1970. The Alaska Earthquake, March 27, 1964: Lessons and 
Conclusions. Geological Survey Professional Paper 546. Washington, D.C.: U.S. 
Government Printing Office. TIC: 251802. 
101069 Eckerman, K.F.; Wolbarst, A.B.; and Richardson, A.C.B. 1988. Limiting Values of 
Radionuclide Intake and Air Concentration and Dose Conversion Factors for 
Inhalation, Submersion, and Ingestion. EPA 520/1-88-020. Federal Guidance Report 
No. 11. Washington, D.C.: U.S. Environmental Protection Agency. ACC: 
MOL.20010726.0072. 
154602 Elders, W.A. 1982. Determination of Fracture History in Geothermal Reservoirs 
Through Study of Minerals. Fractures in Geothermal Reservoirs. Special Report 
No. 12. Pages 6266. Davis, California: Geothermal Resources Council. TIC: 
249737. 
154632 Elders, W.A. 1987. A Natural Analogue for Near-Field Behaviour in a High Level 
Radioactive Waste Repository in Salt: The Salton Sea Geothermal Field, California, 

USA. Natural Analogues in Radioactive Waste Disposal, Proceedings, Symposium 
held in Brussels, Belgium, 2830 April 1987. Cme, B. and Chapman, N.A., eds. 
EUR 11037 EN. Pages 342353. Norwell, Massachusetts: Graham & Trotman. 
TIC: 247254. 
157502 Elders, W.A. and Cohen, L.H. 1983. The Salton Sea Geothermal Field, California, 
as a Near-Field Natural Analog of a Radioactive Waste Repository in Salt. 
BMI/ONWI-513. Columbus, Ohio: Battelle Memorial Institute, Office of Nuclear 
Waste Isolation. TIC: 251848 
100145 Fabryka-Martin, J.T.; Wolfsberg, A.V.; Dixon, P.R.; Levy, S.S.; Musgrave, J.A.; and 
Turin, H.J. 1997. Summary Report of Chlorine-36 Studies: Sampling, Analysis, and 
Simulation of Chlorine-36 in the Exploratory Studies Facility. LA-13352-MS. Los 
Alamos, New Mexico: Los Alamos National Laboratory. ACC: 
MOL.19980812.0254. 
168021 Federal Commission of Electricity. 2003. Report on the Televiewer Log of the 
Boreholes PB-1 and PB-3 and Well PB-4 in Nopal, Municipality of Aldama, 
Chihuahua. Chihuahua, Mexico: Federal Commission of Electricity. ACC: 
MOL.20040108.0362. 
156668 Fetter, C.W. 2001. Applied Hydrogeology. 4th Edition. Upper Saddle River, New 
Jersey: Prentice Hall. TIC: 251142. 
105591 Finch, R.J. and Ewing, R.C. 1991. Alteration of Natural UO2 Under Oxidizing 
Conditions from Shinkolobwe, Katanga, Zaire: A Natural Analogue for the Corrosion 
of Spent Fuel. Radiochimica Acta, 52/53, 395401. Mnchen, Germany: R. 
Oldenbourg Verlag. TIC: 237035. 
127908 Finch, R.J. and Ewing, R.C. 1992. Alteration of Natural Uranyl Oxide Hydrates in 
Si-Rich Groundwaters: Implications for Uranium Solubility. Scientific Basis for 
Nuclear Waste Management XV, Symposium held November 47, 1991, Strasbourg, 
France. Sombret, C.G., ed. 257, 465472. Pittsburgh, Pennsylvania: Materials 
Research Society. TIC: 204618. 
113030 Finch, R.J. and Ewing, R.C. 1992. The Corrosion of Uraninite Under Oxidizing 
Conditions. Journal of Nuclear Materials, 190, 133156. Amsterdam, The 
Netherlands: Elsevier Science Publishers. TIC: 246369. 
104367 Finsterle, S. 1999. ITOUGH2 Users Guide. LBNL-40040. Berkeley, California: 
Lawrence Berkeley National Laboratory. TIC: 243018. 
156815 Flexser, S. 1991. Hydrothermal Alteration and Past and Present Thermal Regimes 
in the Western Moat of Long Valley Caldera. Journal of Volcanology and 
Geothermal Research, 48, 303318. Amsterdam, The Netherlands: Elsevier. TIC: 
251279. 

156351 Flint, A.L.; Flint, L.E.; Bodvarsson, G.S.; Kwicklis, E.M.; and Fabryka-Martin, J. 
2001. Evolution of the Conceptual Model of Unsaturated Zone Hydrology at Yucca 
Mountain, Nevada. Journal of Hydrology, 247, (12), 130. New York, New York: 
Elsevier. TIC: 250932. 
157411 Flint, A.L.; Flint, L.E.; Kwicklis, E.M.; Fabryka-Martin, J.T.; and Bodvarsson, G.S. 
2002. Estimating Recharge at Yucca Mountain, Nevada, USA: Comparison of 
Methods. Hydrogeology Journal, 10, (1), 180240. Berlin, Germany: Springer- 
Verlag. TIC: 251765. 
156355 Forster, C.B.; Caine, J.S.; Schulz, S.; and Nielson, D.L. 1997. Fault Zone 
Architecture and Fluid Flow: An Example from Dixie Valley, Nevada. Proceedings, 
Twenty-Second Workshop on Geothermal Reservoir Engineering, January 2729, 
1997. Workshop Report SGP-TR-155. Pages 123130. Stanford, California: 
Stanford University. TIC: 249200. 
105419 Fournier, R.O. 1992. Water Geothermometers Applied to Geothermal Energy. 
Application of Geochemistry in Geothermal Reservoir Development. D'Amore, F., 
ed. Pages 3769. New York, New York: United Nations Institute for Training and 
Research. TIC: 251141. 
156245 Fournier, R.O. 1989. Geochemistry and Dynamics of the Yellowstone National 
Park Hydrothermal System. Annual Review of Earth and Planetary Sciences, 17, 
1353. Palo Alto, California: Annual Reviews. TIC: 250818. 
154614 Fournier, R.O. 1985. Self-Sealing and Brecciation Resulting from Quartz 
Deposition Within Hydrothermal Systems. Water-Rock Interaction, A Collection of 
Papers Presented at the Fourth International Symposium on Water-Rock Interaction 
(W.R.I.), Organized by the Sub-Group on Water-Rock Interaction, a Part of the 
Commission on Hydrogeochemistry (I.A.G.C.), held in Misasa, Japan, on August 29 
September 8, 1983. Pages 137140. Amsterdam, The Netherlands: Elsevier. TIC: 
249755. 
154527 Fournier, R.O.; Pisto, L.M.; Howell, B.B.; and Hutchinson, R.A. 1993. Taming a 
Wild Geothermal Research Well in Yellowstone National Park. Geothermal 
Resources Council Transactions, 17, 3336. Davis, California: Geothermal 
Resources Council. TIC: 249701. 
156247 Fournier, R.O.; Thompson, J.M.; and Hutchinson, R.A. 1992. The Geochemistry of 
Hot Spring Waters at Norris Geyser Basin, Yellowstone National Park, USA. 
Water-Rock Interaction, Proceedings of the 7th International Symposium on Water- 
Rock InteractionWRI-7, Park City, Utah, 1318 July 1992. Kharaka, Y.K. and 
Maest, A.S., eds. 2, 12891292. Brookfield, Vermont: A.A. Balkema. TIC: 208527. 
156246 Fournier, R.O.; Thompson, J.M.; Cunningham, C.G.; and Huchinson, R.A. 1991. 
Conditions Leading to a Recent Small Hydrothermal Explosion at Yellowstone 
National Park. Geological Society of America Bulletin, 103, (8), 11141120. 
Boulder, Colorado: Geological Society of America. TIC: 250862. 

156817 Fournier, R.O.; White, D.E.; and Truesdell, A.H. 1976. Convective Heat Flow in 
Yellowstone National Park. Proceedings of the Second United Nations Symposium 
on the Development and Use of Geothermal Resources, San Francisco, California, 
2029, May 1975. 1, 731739. Washington, D.C.: U.S. Government Printing Office. 
TIC: 251430. 
127326 Francis, N.D. 1997. The Base-Case Thermal Properties for TSPA-VA Modeling. 
Memorandum from N.D. Francis (SNL) to Distribution, April 16, 1997. ACC: 
MOL.19980518.0229. 
101173 Freeze, R.A. and Cherry, J.A. 1979. Groundwater. Englewood Cliffs, New Jersey: 
Prentice-Hall. TIC: 217571. 
100575 Fridrich, C.J.; Dudley, W.W., Jr.; and Stuckless, J.S. 1994. Hydrogeologic Analysis 
of the Saturated-Zone Ground-Water System, under Yucca Mountain, Nevada. 
Journal of Hydrology, 154, 133168. Amsterdam, The Netherlands: Elsevier. TIC: 
224606. 
168019 Garay Jimnez, F.; Angn, R.P.; and Vargas, A.R. 2003. Study of Geophysical Logs 
in Four Wells Located in the Nopal Field, Aldama, Chihuahua, for the University of 
Chihuahua. Chihuahua, Mexico: Federal Commission of Electricity. ACC: 
MOL.20040108.0360. 
156602 Garger, E.K.; Hoffman, F.O.; and Miller, C.W. 1996. Model Testing Using 
Chernobyl Data: III. Atmospheric Resuspension of Radionuclides in Ukrainian 
Regions Impacted by Chernobyl Fallout. Health Physics, 70, (1), 1824. New 
York, New York: Pergamon. TIC: 251064. 
151483 Garger, E.K.; Hoffman, F.O.; Thiessen, K.M.; Galeriu, D.; Kryshev, A.I.; Lev, T.; 
Miller, C.W.; Nair, S.K.; Talerko, N.; and Watkins, B. 1999. Test of Existing 
Mathematical Models for Atmospheric Resuspension of Radionuclides. Journal of 
Environmental Radioactivity, 42, (23), 157175. London, England: Elsevier 
Science. TIC: 248525. 
157542 Gauthier-Lafaye, F. 1996. Introduction to the Oklo Problematic. OKLO Working 
Group, Proceedings of the Fourth Joint EC-CEA Progress and Final Meeting Held in 
Saclay, France, on 22 and 23 June 1995. Blanc, P.L. and von Maravic, H., eds.. 
EUR 16704 EN. Pages 516. Luxembourg, Luxembourg: Office for Official 
Publications of the European Communities. TIC: 251757. 
157499 Gauthier-Lafaye, F.; Ledoux, E.; Smellie, J.; Louvat, D.; Michaud, V.; Prez del 
Villar, L.; Oversby, V.; and Bruno, J. 2000. OKLO Natural Analogue Phase II, 
Behavior of Nuclear Reaction Products in a Natural Environment. EUR 19139 EN. 
Luxembourg, Luxembourg: Commission of the European Communities. TIC: 
251886. 
156338 Giggenbach, W.F. 1997. The Origin and Evolution of Fluids in Magmatic 
Hydrothermal Systems. Chapter 15 of Geochemistry of Hydrothermal Ore Deposits. 

3rd Edition. Barnes, H.L., ed. New York, New York: John Wiley & Sons. TIC: 
250951. 
157516 Gill, D. 2001. The Art and Archaeology of Attica. Swansea, Wales: David Gill. 
Accessed January 30, 2002. TIC: 251750. 
http://www.davidgill.co.uk/attica/thorikos947.htm 
156812 Goff, F. and Gardner, J.N. 1994. Evolution of a Mineralized Geothermal System, 
Valles Caldera, New Mexico. Economic Geology, 89, 18031832. El Paso, Texas: 
Economic Geology Publishing Company. TIC: 251278. 
156808 Goff, F.; Gardner, J.N.; Hulen, J.B.; Nielson, D.L.; Charles, R.; WoldeGabriel, G.; 
Vuataz, F-D.; Musgrave J.A.; Shevenell, L.; and Kennedy B.M. 1992. The Valles 
Caldera Hydrothermal System, Past and Present, New Mexico, USA. Scientific 
Drilling, 3, 181204. New York, New York: Springer-Verlag. TIC: 251277. 
157422 Golany, G.S. 1983. Earth-Sheltered Habitat, History, Architecture and Urban 
Design. New York, New York: Van Nostrand Reinhold. TIC: 251577. 
157423 Golany, G.S. 1989. Urban Underground Space Design in China, Vernacular and 
Modern Practice. Newark, New Jersey: University of Delaware Press. TIC: 251579. 
156820 Goldman, M.; Catlin, R.J.; and Anspaugh, L. 1987. Health and Environmental 
Consequences of the Chernobyl Nuclear Power Plant Accident. DOE/ER-0332. 
Washington, D.C.: U.S. Department of Energy. TIC: 251267. 
168528 Goldstein, S.J.; Murrell, M.T.; Simmons, A.M.; Oliver, R.D.; Dobson, P.F.; Reyes, 
I.A.; and de la Garza, R. 2003. Evidence for Radium Mobility at the Nopal I 
Uranium Deposit, Pea Blanca, Mexico. Abstracts with ProgramsGeological 
Society of America, 35, (6), 436. Boulder, Colorado: Geological Society of America. 
TIC: 254862. 
119228 Grambow, B.; Jercinovic, M.J.; Ewing, R.C.; and Byers, C.D. 1986. Weathered 
Basalt Glass: A Natural Analogue for the Effects of Reaction Progress on Nuclear 
Waste Glass Alteration. Scientific Basis for Nuclear Waste Management IX, 
Symposium held September 911, 1985, Stockholm, Sweden. Werme, L.O., ed. 50, 
263272. Pittsburgh, Pennsylvania: Materials Research Society. TIC: 203664. 
156218 Grand, P.M. 1967. Prehistoric Art, Paleolithic Painting and Sculpture. Greenwich, 
Connecticut: New York Graphic Society. TIC: 250804. 
154663 Grindley, G.W. 1965. The Geology, Structure, and Exploitation of the Wairakei 
Geothermal Field, Taupo New Zealand. Bulletin n.s. 75. Wellington, New Zealand: 
New Zealand Geological Survey, Department of Scientific and Industrial Research. 
TIC: 249790. 
154531 Grindley, G.W. and Browne, P.R.L. 1976. Structural and Hydrological Factors 
Controlling the Permeabilities of Some Hot-Water Geothermal Fields. Proceedings 

of the Second United Nations Symposium on the Development and Use of Geothermal 
Resources, San Francisco, California, USA, 2029 May 1975. 1, 377386. 
Washington, D.C.: U.S. Government Printing Office. TIC: 249789. 
107832 Grossenbacher, K. and Faybishenko, B. 1997. Spacing of Thermally Induced 
Columnar Joints in Basalt: Variation with Depth. Berkeley, California: Lawrence 
Berkeley National Laboratory, Earth Sciences Division. TIC: 247646. 
107835 Gudzenko, V. 1992. Some Problems of the Radionuclides Migration Research. 
Third Research Co-Ordination Meeting on Nuclear Techniques in the Study of 
Pollutant Transport in the Environment: Interaction of Solutes with Geological 
Media (Methodological Aspects), Vienna, Austria, 2225 June 1992. Vienna, 
Austria: International Atomic Energy Agency. TIC: 247334. 
107834 Gudzenko, V.V.; Klimchuk, A.B.; Yablokova, N.L.; Gudzenko, G.I.; and Golikova, 
T.A. 1991. Osushchestvit' Radiogidrogeologicheskie Obsledovanie Tekhnogennykh 
Podzemnykh Polosteig. Kieva s Tsel'yu Otsenki Skorosti Proniknoveniya 
Radionuklidov v Podzemnuyu Gidrosferu (To Provide Radiohydrogeological 
Observations in Underground Adits of the City of Kiev for the Purpose of Evaluating 
the Velocity of Radionuclide Migration in the Groundwater System). Kiev, Ukraine: 
Institute of Geological Sciences of the Ukrainian National Academy of Sciences. 
ACC: MOL.20000609.0003. 
125020 Gudzenko, V.V.; Shestopalov, V.M.; and Sobotovich, E.V. 1990. The Isotopic 
Studies of Subsurface Water Protection from Radioactive Pollution in the Areas of 
Nuclear Power Plant Siting. The International Journal of Radiation Applications 
and Instrumentation. Part E: Nuclear Geophysics, 4, (1), 119124. Oxford, England: 
Pergamon Press. TIC: 247327. 
156310 Gunderson, R.; Ganefianto, N.; Riedel, K.; Sirad-Azwar, L.; and Suleiman, S. 2000. 
Exploration Results in the Sarulla Block, North Sumatra, Indonesia. Proceedings 
of the World Geothermal Congress 2000, Kyushu-Tohoku, Japan, May 28June 10, 
2000. Iglesias, E.; Blackwell, D.; Hunt, T.; Lund, J.; and Tamanyu, S.; eds. Pages 
11831188. Auckland, New Zealand: International Geothermal Association. TIC: 
250933. 
156361 Gunderson, R.P.; Dobson, P.F.; Sharp, W.D.; Pudjianto, R.; and Hasibuan, A. 1995. 
Geology and Thermal Features of the Sarulla Contract Area, North Sumatra, 
Indonesia. Proceedings of the World Geothermal Congress 1995, Florence, Italy, 
May 1831, 1995. Barbier, E.; Frye, G.; Iglesias, E.; and Plmason, G.; eds. 2, 687 
692. Auckland, New Zealand: International Geothermal Association. TIC: 250774. 
157471 Gupalo, T.A. 2001. Development of Quantitative Criteria for Suitability of Rock 
Mass for Safe Long-Term Storage of Waste from Weapons-Grade Plutonium 
Production, Illustrated by Krasnoyarsk Mining Chemical Combine, Summary 
Technical Report (01.10.199728.02.2001). Project #307B-97. Moscow, Russia: 
All-Russian Research and Design Institute of Production Engineering (VNIPIPT). 

157470 Gupalo, T.A. 1999. Development of Quantitative Criteria for Suitability of Rock 
Mass for Safe Long-Term Storage of Waste from Weapon Plutonium Production, 
Illustrated by Krasnoyarsk Mining Chemical Combine, Annual Report for the Second 
Year (01.10.9830.09.99). Project #307B-97. Moscow, Russia: All-Russian 
Research and Design Institute of Production Engineering (VNIPIPT). Copyright 
Requested Library Tracking Number-251898. 
105175 Haar, L.; Gallagher, J.S.; and Kell, G.S. 1984. NBS/NRC Steam Tables: 
Thermodynamic and Transport Properties and Computer Programs for Vapor and 
Liquid States of Water in SI Units. New York, New York: Hemisphere Publishing 
Corporation. TIC: 241793. 
100350 Hardin, E.L. 1998. Near-Field/Altered-Zone Models Report. UCRL-ID-129179 DR. 
Livermore, California: Lawrence Livermore National Laboratory. ACC: 
MOL.19980504.0577. 
150043 Hardin, E.L. and Chesnut, D.A. 1997. Synthesis Report on Thermally Driven 
Coupled Processes. UCRL-ID-128495. Livermore, California: Lawrence Livermore 
National Laboratory. TIC: 234838. 
105967 Hay, R.L. 1978. Geologic Occurrence of Zeolites. Natural Zeolites, Occurrence, 
Properties, Use, A Selection of Papers Presented at Zeolite, 76, an International 
Conference on the Occurrence, Properties, and Utilization of Natural Zeolites, 
Tucson, Arizona, June 1976. Sand, L.B. and Mumpton, F.A., eds. Pages 135143. 
New York, New York: Pergamon Press. TIC: 206755. 
157478 Heath, M.J. 1995. Rock Matrix Diffusion as a Mechanism for Radionuclide 
Retardation: Natural Radioelement Migration in Relation to the Microfractography 
and Petrophysics of Fractured Crystalline Rock, (Report on Phase 1, March 1991 
February 1993). EUR 15977 EN. Luxembourg, Luxembourg: Commission of the 
European Communities. TIC: 251887. 
156315 Hedenquist, J.W. 1991. Boiling and Dilution in the Shallow Portion of the 
Waiotapu Geothermal System, New Zealand. Geochimica et Cosmochimica Acta, 
55, (10), 27532765. New York, New York: Pergamon Pess. TIC: 250973. 
156248 Hildreth, W.; Christiansen, R.L.; and O'Neil, J.R. 1984. Catastrophic Isotopic 
Modification of Rhyolitic Magma at Times of Caldera Subsidence, Yellowstone 
Plateau Volcanic Field. Journal of Geophysical Research, 89, (B10), 83398369. 
Washington, D.C.: American Geophysical Union. TIC: 250819. 
156616 Hoffman, F.O.; Thiessen, K.M.; and Watkins, B. 1996. Opportunities for the 
Testing of Environmental Transport Models Using Data Obtained Following the 
Chernobyl Accident. Health Physics, 70, (1), 57. New York, New York: 
Pergamon. TIC: 251067. 
125081 Hofmann, B.A. 1989. Geochemical Analogue Study in the Krunkelbach Mine, 
Menzenschwand, Southern Germany: Geology and Water-Rock Interaction. 

Scientific Basis for Nuclear Waste Management XII, Symposium held October 1013, 
1988, Berlin, Germany. Lutze, W. and Ewing, R.C., eds. 127, 921926. Pittsburgh, 
Pennsylvania: Materials Research Society. TIC: 203660. 
106045 Honda, S. and Muffler, L.J.P. 1970. Hydrothermal Alteration in Core from 
Research Drill Hole Y-1, Upper Geyser Basin, Yellowstone National Park, 
Wyoming. American Mineralogist, 55, 17141737. Washington, D.C.: 
Mineralogical Society of America. TIC: 219076. 
156362 Horne, R.N. 1982. Geothermal Reinjection Experience in Japan. Journal of 
Petroleum Technology, 34, 495503. Dallas, Texas: Society of Petroleum Engineers 
of AIME. TIC: 250934. 
157412 Hubbell, J.M. 1993. Perched Ground Water Monitoring in the Subsurface Disposal 
Area of the Radioactive Waste Disposal Complex, FY-1993. EDF Serial Number 
ER&WM-EDF-002293. Idaho Falls, Idaho: EG&G Idaho. TIC: 251839. 
157413 Hubbell, J.M. 1995. Perched Ground Water Monitoring at the Subsurface Disposal 
Area of the Radioactive Waste Management Complex, Idaho, FY-94. INEL-95/149. 
Idaho Falls, Idaho: U.S. Department of Energy, Idaho Operations Office. TIC: 
251840. 
154600 Hulen, J.B. and Lutz, S.J. 1999. Altered Volcanic Rocks as Hydrologic Seals on the 
Geothermal System of Medicine Lake Volcano, California. Geothermal Resources 
Council Bulletin, 28, (7), 217222. Davis, California: Geothermal Resources 
Council. TIC: 249735. 
156813 Hulen, J.B. and Nielson, D.L. 1986. Hydrothermal Alteration in the Baca 
Geothermal System, Redondo Dome, Valles Caldera, New Mexico. Journal of 
Geophysical Research, 91, (B2), 18671886. Washington, D.C.: American 
Geophysical Union. TIC: 251351. 
157491 Humphrey, T.G. and Tingey, F.H. 1978. The Subsurface Migration of Radionuclides 
at the Radioactive Waste Management Complex, 19761977. TREE 1171. Idaho 
Falls, Idaho: U.S. Department of Energy, Idaho Operations Office. TIC: 251849. 
157485 IAEA (International Atomic Energy Agency) 1999. Use of Natural Analogs to 
Support Radionuclide Transport Models for Deep Geological Repositories for Long 
Lived Radioactive Wastes. IAEA-TECDOC-1109. Vienna, Austria: International 
Atomic Energy Agency. TIC: 251889. 
156750 IAEA (International Atomic Energy Agency) 1991. The International Chernobyl 
Project, Assessment of Radiological Consequences and Evaluation of Protective 
Measures, Summary Brochure. Vienna, Austria: International Atomic Energy 
Agency. TIC: 251269. 
155188 IAEA (International Atomic Energy Agency) 2001. An International Peer Review of 
the Biosphere Modelling Programme of the US Department of Energys Yucca 

Mountain Site Characterization Project, Report of the IAEA International Review 
Team. Vienna, Austria: International Atomic Energy Agency. TIC: 250092. 
156448 IFC (International Formulation Committee) 1967. The 1967 IFC Formulation for 
Industrial Use, A Formulation of the Thermodynamic Properties of Ordinary Water 
Substance. Dsseldorf, Germany: International Formulation Committee of the Sixth 
International Conference on the Properties of Steam. TIC: 224838. 
156430 INEL (Idaho National Engineering Laboratory) 1995. A Comprehensive Inventory of 
Radiological and Nonradiological Contaminants in Waste Buried or Projected to be 
Buried in the Subsurface Disposal Area of the INEL RWMC During the Years, 1984 
2003. INEL/95-0135, Vol. 1. Idaho Falls, Idaho: Idaho National Engineering 
Laboratory, Lockheed Idaho Technologies Company. TIC: 251896. 
137537 Ingebritsen, S.E. and Sorey, M.L. 1988. Vapor-Dominated Zones Within 
Hydrothermal Systems: Evolution and Natural State. Journal of Geophysical 
Research, 93, (B11), 1363513655. Washington, D.C.: American Geophysical 
Union. TIC: 247149. 
156617 Isaksson, M. and Erlandsson, B. 1998. Models for the Vertical Migration of 137Cs 
in the GroundA Field Study. Journal of Environmental Radioactivity, 41, (2), 
163182. New York, New York: Elsevier. TIC: 251068. 
156345 Itoi, R.; Fukuda, M.; Jinno, K.; Hirowatari, K.; Shinohara, N.; and Tomita, T. 1989. 
Long-Term Experiments of Waste Water Injection in the Otake Geothermal Field, 
Japan. Geothermics, 18, (1/2), 153159. New York, New York: Pergamon Press. 
TIC: 250935. 
156346 Itoi, R.; Fukuda, M.; Jinno, K.; Shimizu, S.; and Tomita, T. 1987. Field 
Experiments of Injection in the Otake Geothermal Field, Japan. Geothermal 
Resources Council Transactions, 11, 541545. Davis, California: Geothermal 
Resources Council. TIC: 250936. 
156347 Itoi, R.; Maekawa, H.; Fukuda, M.; Jinno, K.; Hatanaka, K.; Yokoyama, T.; and 
Shimizu, S. 1984. Experimental Study on the Silica Deposition in a Porous 
Medium. Geothermal Resources Council Transactions, 8, 301304. Davis, 
California: Geothermal Resources Council. TIC: 250937. 
156352 Itoi, R.; Maekawa, H.; Fukuda, M.; Jinno, K.; Hatanaka, K.; Yokoyama, T.; and 
Shimizu, S. 1986. Study on Decrease of Reservoir Permeability Due to Deposition 
of Silica Dissolved in Reinjection Water. Journal of the Geothermal Research 
Society of Japan, 8, (3), 229241. Kawasaki, Japan: Do Gakkai. TIC: 250938. 
156818 Ivanov, Y.A. 2001. Dynamics of Redistribution of Radionuclides in Soils and 
Plants. Chornobyl [Chernobyl], The Exclusion Zone, Collected Papers. 
Bar'yakhtar, V.G. ed. 4776. Kyiv, Naukova Dumka: National Academy of Sciences 
of Ukraine. On Order Library Tracking Number-251864. 

156864 Jacob, P. and Likhtarev, I., eds. 1996. Pathway Analysis and Dose Distributions. 
Joint Study Project No. 5. Final Report EUR 16541 EN. Brussels, Belgium: 
European Commission Directorate-General XII. TIC: 251884. 
154296 Jagnow, D.H. 1999. Geology of Kartchner Caverns State Park, Arizona. Journal 
of Cave and Karst Studies, 61, (2), 4958. Huntsville, Alabama: National 
Speleological Society. TIC: 249658. 
157489 Jarvis, N.V.; Andreoli, M.A.G.; and Read, D. 1997. The Steenkampskraal Natural 
Analogue Study and Nuclear Waste Disposal in South Africa. Seventh EC Natural 
Analogue Working Group Meeting, Proceedings of an International Workshop held 
in Stein am Rhein, Switzerland from 28 to 30 October 1996. von Maravic, H. and 
Smellie, J., eds. EUR 17851 EN, Pages 926. Luxembourg, Luxembourg: 
Commission of the European Communities. TIC: 247461. 
157463 Jen, C-P. and Li, S-H. 2001. Effects of Hydrodynamic Chromatography on 
Colloid-Facilitated Migration of Radionuclides in the Fractured Rock. Waste 
Management, 21, (6), 499509. New York, New York: Elsevier. TIC: 251645. 
156643 Jensen, C.L. and Horne, R.N. 1983. Matrix Diffusion and its Effect on the 
Modeling of Tracer Returns from the Fractured Geothermal Reservoir at Wairakei, 
New Zealand. Proceedings, Ninth Workshop, Geothermal Reservoir Engineering, 
December 1315, 1983, Stanford, California. Workshop Report SGP-TR-74. Pages 
323329. Stanford, California: Stanford University. TIC: 248733. 
157500 Jensen, K.A. and Ewing, R.C. 2001. The Oklobondo Natural Fission Reactor, 
Southeast Gabon: Geology, Mineralogy, and Retardation of Nuclear-Reaction 
Products. Geological Society of America Bulletin, 113, (1), 3262. Boulder, 
Colorado: Geological Society of America. TIC: 251743. 
144605 Jercinovic, M.J. and Ewing, R.C. 1987. Basaltic Glasses from Iceland and the Deep 
Sea: Natural Analogues to Borosilicate Nuclear Waste-Form Glass. JSS Project 
Technical Report 88-01. Stockholm, Sweden: Swedish Nuclear Fuel and Waste 
Management Company. TIC: 205668. 
125289 Jercinovic, M.J.; Ewing, R.C.; and Byers, C.D. 1986. Alteration Products of Basalt 
Glass from Frenchman Springs Flow, Wanapum Basalts, Hanford, Washington. 
Nuclear Waste Management II, Third Annual Symposium on Ceramics in Nuclear 
Waste Management, April 2830, 1986, Chicago, Illinois. Clark, D.E.; White, W.B.; 
and Machiels, A.J., eds. Advances in Ceramics Volume 20. Pages 671679. 
Westerville, Ohio: American Ceramic Society. TIC: 210019. 
157474 Jerden, J.L., Jr. and Sinha, A.K. 2001. Natural Attenuation of Uranium in an 
Oxidizing Rock-Soil-Groundwater System: Coles Hill Uranium Deposit, Virginia. 
Abstracts with ProgramsGeological Society of America. Page A364. Boulder, 
Colorado: Geological Society of America. TIC: 251677. 

125291 Johnson, A.B., Jr. and Francis, B. 1980. Durability of Metals from Archaeological 
Objects, Metal Meteorites, and Native Metals. PNL-3198. Richland, Washington: 
Pacific Northwest Laboratory. TIC: 229619. 
101630 Johnson, J.W.; Knauss, K.G.; Glassley, W.E.; DeLoach, L.D.; and Tompson, A.F.B 
1998. Reactive Transport Modeling of Plug-Flow Reactor Experiments: Quartz and 
Tuff Dissolution at 240C. Journal of Hydrology, 209, 81111. Amsterdam, The 
Netherlands: Elsevier. TIC: 240986. 
156620 Jonsson, B.; Forseth, T.; and Ugedal, O. 1999. Chernobyl Radioactivity Persists in 
Fish. Nature, 400, (6743), 417. London, England: Macmillan. TIC: 251069. 
157472 Jove Colon, C.F.; Brady, P.V.; Siegel, M.D.; and Lindgren, E.R. 2001. Historical 
Case Analysis of Uranium Plume Attenuation. NUREG/CR-6705. Washington, 
D.C.: U.S. Nuclear Regulatory Commission. TIC: 251760. 
156622 Kashparov, V.A.; Lundin, S.M.; Kadygrib, A.M.; Protsak, V.P.; Levtchuk, S.E.; 
Yoschenko, V.I.; Kashpur, V.A.; and Talerko, N.M. 2000. Forest Fires in the 
Territory Contaminated as a Result of the Chernobyl Accident: Radioactive Aerosol 
Resuspension and Exposure of Fire-Fighters. Journal of Environmental 
Radioactivity, 51, 281298. New York, New York: Elsevier. TIC: 251070. 
157400 Kashparov, V.A.; Lundin, S.M.; Khomutinin, Yu.V.; Kaminsky, S.P.; Levchuk, S.E.; 
Protsak, V.P.; Kadygrib, A.M.; Zvarich, S.I.; Yoschenko, V.I.; and Tschiersch, J. 
2001. Soil Contamination with 90Sr in the Near Zone of the Chernobyl Accident. 
Journal of Environmental Radioactivity, 56, (3), 285298. New York, New York: 
Elsevier. TIC: 251572. 
156623 Kashparov, V.A.; Protsak, V.P.; Ahamdach, N.; Stammose, D.; Peres, J.M.; 
Yoschenko, V.I.; and Zvarich, S.I. 2000. Dissolution Kinetics of Particles of 
Irradiated Chernobyl Nuclear Fuel: Influence of pH and Oxidation State on the 
Release of Radionuclides in the Contaminated Soil of Chernobyl. Journal of 
Nuclear Materials, 279, (23), 225233. New York, New York: Elsevier. TIC: 
251071. 
152663 Keith, T.E.C. and Muffler, L.J.P. 1978. Minerals Produced During Cooling and 
Hydrothermal Alteration of Ash Flow Tuff from Yellowstone Drill Hole Y-5. 
Journal of Volcanology and Geothermal Research, 3, 373402. Amsterdam, The 
Netherlands: Elsevier. TIC: 219077. 
106316 Keith, T.E.C.; White, D.E.; and Beeson, M.H. 1978. Hydrothermal Alteration and 
Self-Sealing in Y-7 and Y-8 Drill Holes in Northern Part of Upper Geyser Basin, 
Yellowstone National Park, Wyoming. Geological Survey Professional Paper 1054- 
A. Washington, D.C.: U.S. Government Printing Office. TIC: 219043. 
156339 Kennedy, B.M. and Truesdell, A.H. 1996. The Northwest Geysers High- 
Temperature Reservoir: Evidence for Active Magmatic Degassing and Implications 

for the Origin of the Geysers Geothermal Field. Geothermics, 25, (3), 365387. 
New York, New York: Pergamon. TIC: 250939. 
103282 Kersting, A.B.; Efurd, D.W.; Finnegan, D.L.; Rokop, D.J.; Smith, D.K.; and 
Thompson, J.L. 1999. Migration of Plutonium in Ground Water at the Nevada Test 
Site. Nature, 397, (6714), 56-59. London, England: Macmillan Journals. TIC: 
243597. 
125677 Khoury, H.N.; Salameh, E.; Clark, I.D.; Fritz, P.; Milodowski, A.E.; Cave, M.R.; 
Bajjali, W.; and Alexander, W.R. 1992. A Natural Analogue of High pH Cement 
Pore Waters from the Maqarin Area of Northern Jordan: I. Introduction to the Site. 
Journal of Geochemical Exploration, 46, (1), 117132. New York, New York: 
Elsevier. TIC: 247469. 
157444 King, M.S. and Paulsson, B.N.P. 1981. Acoustic Velocities in a Heated Block of 
Granite Subjected to Uniaxial Stress. Geophysical Research Letters, 8, (7), 669 
702. Washington, D.C.: American Geophysical Union. TIC: 251659. 
113930 Kingston, W.L. and Whitbeck, M. 1991. Characterization of Colloids Found in 
Various Groundwater Environments in Central and Southern Nevada. 
DOE/NV/10384-36. Las Vegas, Nevada: Desert Research Institute, Water Resources 
Center. ACC: NNA.19930607.0073. 
154460 Kneafsey, T.J.; Apps, J.A.; and Sonnenthal, E.L. 2001. Tuff Dissolution and 
Precipitation in a Boiling, Unsaturated Fracture. Back to the FutureManaging 
the Back End of the Nuclear Fuel Cycle to Create a More Secure Energy Future, 
Proceedings of the 9th International High-Level Radioactive Waste Management 
Conference (IHLRWM), Las Vegas, Nevada, April 29May 3, 2001. La Grange Park, 
Illinois: American Nuclear Society. TIC: 247873. 
107839 Knutson, C.F.; McCormick, K.A.; Smith, R.P.; Hackett, W.R.; O'Brien, J.P.; and 
Crocker, J.C. 1990. FY 89 Report RWMC Vadose Zone Basalt Characterization. 
EGG-WM-8949. Idaho Falls, Idaho: EG&G Idaho. TIC: 245912. 
156624 Konoplev, A.V.; Bulgakov, A.A.; Hoffman, F.O.; Kanyar, B.; Lyashenko, G.; Nair, 
S.K.; Popov, A.; Raskob, W.; Thiessen, K.M.; Watkins, B.; and Zheleznyak, M. 
1999. Validation of Models of Radionuclide Wash-Off from Contaminated 
Watersheds Using Chernobyl Data. Journal of Environmental Radioactivity, 42, 
131141. New York, New York: Elsevier. TIC: 251072. 
109939 Ku, T.-L.; Luo, S.; Leslie, B.W.; and Hammond, D.E. 1992. Decay-Series 
Disequilibria Applied to the Study of Rock-Water Interaction and Geothermal 
Systems. Chapter 18 of Uranium-Series Disequilibrium: Applications to Earth, 
Marine, and Environmental Sciences. Ivanovich, M. and Harmon, R.S., eds. 2nd 
Edition. New York, New York: Oxford University Press. TIC: 234680. 

157506 Kukhar', V.; Poyarkov, V.; and Kholosha, V. 2000. Radioactive Waste, Storage and 
Disposal Sites. Chapter 4 of The Chornobyl Accident, A Comprehensive Risk 
Assessment. Vargo, G.J., ed. Columbus, Ohio: Battelle Press. TIC: 251266. 
157604 Kung, S.; Chipera, S.J.; and Reimus, P.W. 2001. Characteristics of Natural 
Colloids in the Saturated Alluvium South of Yucca Mountain, Nevada. Eos, 
Transactions (Supplement), 82, (47), F472. Washington, D.C.: American 
Geophysical Union. TIC: 251883. 
100051 Langmuir, D. 1997. Aqueous Environmental Geochemistry. Upper Saddle River, 
New Jersey: Prentice Hall. TIC: 237107. 
155885 Larsen, G.; Grnvold, K.; and Thorarinsson, S. 1979. Volcanic Eruption through a 
Geothermal Borehole at Namafjall, Iceland. Nature, 278, (5706), 707710. 
London, England: Macmillan Journals. TIC: 250655. 
156626 Lazjuk, G.I.; Kirillova, I.A.; Nikolaev, D.L.; Novikova, I.V.; Formina, Z.N.; and 
Khmel, R.D. 1995. Frequency Changes of Inherited Anomalies in the Republic of 
Belaurs After the Chernobyl Accident. Radiation Protection Dosimetry, 62, (1/2), 
7174. Ashford, Kent, United Kingdom: Nuclear Technology Publishing. TIC: 
251135. 
125854 Lebedev, I.A.; Myasoedov, B.F.; Pavlotskaya, F.I.; and Frenkel', V.Ya. 1992. 
Plutonium Content in Soils of the European Part of the Country after the Accident at 
Chernobyl Nuclear Generating Station. Atomic Energy, A Translation of Atomnaya 
Energiya, 72, (6), 515520. New York, New York: Consultants Bureau. TIC: 
247771. 
100153 LeCain, G.D. 1997. Air-Injection Testing in Vertical Boreholes in Welded and 
Nonwelded Tuff, Yucca Mountain, Nevada. Water-Resources Investigations Report 
96-4262. Denver, Colorado: U.S. Geological Survey. ACC: MOL.19980310.0148. 
155241 Lee, J.H. 2001. Median Lead Concentration in Groundwater Samples Cited in 
Section 7.3.1.3.4 of the SSPA Report Vol. 1. Memorandum from J.H. Lee (BSC) to 
P. Pasupathi, June 20, 2001, Proj.06/01.049, with enclosure. ACC: 
MOL.20010621.0155. 
156454 Leroi-Gourhan, A. 1982. The Archaeology of Lascaux Cave. Scientific American, 
246, (6), 104112. New York, New York: Scientific American. TIC: 251232. 
101714 Leslie, B.W.; Pearcy, E.C.; and Prikryl, J.D. 1993. Oxidative Alteration of 
Uraninite at the Nopal I Deposit, Mexico: Possible Contaminant Transport and 
Source Term Constraints for the Proposed Repository at Yucca Mountain. Scientific 
Basis for Nuclear Waste Management XVI, Symposium held November 30December 
4, 1992, Boston, Massachusetts. Interrante, C.G. and Pabalan, R.T., eds. 294, 505 
512. Pittsburgh, Pennsylvania: Materials Research Society. TIC: 208880. 

109967 Leslie, B.W.; Pickett, D.A.; and Pearcy, E.C. 1999. Vegetation-Derived Insights on 
the Mobilization and Potential Transport of Radionuclides from the Nopal I Natural 
Analog Site, Mexico. Scientific Basis for Nuclear Waste Management XXII, 
Symposium Held November 30December 4, 1998, Boston, Massachusetts, U.S.A. 
Wronkiewicz, D.J. and Lee, J.H., eds. 556, 833842. Warrendale, Pennsylvania: 
Materials Research Society. TIC: 246426. 
101409 Lichtner, P.C. 1996. Continuum Formulation of Multicomponent-Multiphase 
Reactive Transport. Reactive Transport in Porous Media. Lichtner, P.C.; Steefel, 
C.I.; and Oelkers, E.H., eds. Reviews in Mineralogy Volume 34. Washington, D.C.: 
Mineralogical Society of America. TIC: 236866. 
156428 Lichtner, P.C. 2000. Critique of Dual Continuum Formulations of Multicomponent 
Reactive Transport in Fractured Porous Media. Dynamics of Fluids in Fractured 
Rock, Papers Selected from a Symposium held at Ernest Orlando Lawrence Berkeley 
National Laboratory on Februrary 1012, 1999. Faybishenko, B.; Witherspoon, A.; 
and Benson, S.M.; eds. Geophysical Monograph 122. Pages 281298. Washington, 
D.C.: American Geophysical Union. TIC: 250777. 
156429 Lichtner, P.C. 2001. FLOTRAN User's Manual: Two-Phase Nonisothermal Coupled 
Thermal-Hydrologic-Chemical (THC) Reactive Flow & Transport Code, Version 1.0. 
LA-UR-01-2349. Los Alamos, New Mexico: Los Alamos National Laboratory. TIC: 
250889. 
100771 Lichtner, P.C. and Seth, M. 1996. Multiphase-Multicomponent Nonisothermal 
Reactive Transport in Partially Saturated Porous Media. Proceedings of the 1996 
International Conference on Deep Geological Disposal of Radioactive Waste, 
September 1619, 1996, Winnipeg, Manitoba, Canada. Toronto, Ontario, Canada: 
Canadian Nuclear Society. TIC: 233923. 
121006 Lichtner, P.C.; Keating, G.; and Carey, B.1999. A Natural Analogue for Thermal- 
Hydrological-Chemical Coupled Processes at the Proposed Nuclear Waste 
Repository at Yucca Mountain, Nevada. LA-13610-MS. Los Alamos, New Mexico: 
Los Alamos National Laboratory. TIC: 246032. 
156627 Likar, A.; Omahen, G.; Lipoglavek, M.; and Vidmar, T. 2001. A Theoretical 
Description of Diffusion and Migration of 137Cs in Soil. Journal of Environmental 
Radioactivity, 57, (3), 191201. New York, New York: Elsevier. TIC: 251074. 
108896 Linklater, C.M.; Albinsson, Y.; Alexander, W.R.; Casas, I; McKinley, I.G.; and 
Sellin, P. 1996. A Natural Analogue of High-pH Cement Pore Waters from the 
Maqarin Area of Northern Jordan: Comparison of Predicted and Observed Trace- 
Element Chemistry of Uranium and Selenium. Journal of Contaminant Hydrology, 
21, (14), 5969. Amsterdam, The Netherlands: Elsevier. TIC: 239819. 
154579 Liu, H.H.; Bodvarsson, G.S.; and Pan, L. 2000. Determination of Particle Transfer 
in Random Walk Particle Methods for Fractured Porous Media. Water Resources 

Research, 36, (3), 707713. Washington, D.C.: American Geophysical Union. TIC: 
249733. 
105729 Liu, H.H.; Doughty, C.; and Bodvarsson, G.S. 1998. An Active Fracture Model for 
Unsaturated Flow and Transport in Fractured Rocks. Water Resources Research, 
34, (10), 26332646. Washington, D.C.: American Geophysical Union. TIC: 
243012. 
157526 Llandudno Museum 1998. Virtual Tour - Room 3. Llandudno, North Wales: 
Chardon Trust. Accessed January 31, 2002. http://www.llandudnotourism.
co.uk/museum/english/panel3.htm Copyright Requested Library Tracking 
Number-251574. 
157508 Los', I. and Poyarkov, V. 2000. Individuals, Accident Remediation Personnel, and 
Public Doses. Chapter 6 of The Chornobyl Accident: A Comprehensive Risk 
Assessment. Vargo, G.J., ed. Columbus, Ohio: Battelle Press. TIC: 251266. 
125894 Loshchilov, N.A.; Kashparov, V.A.; and Polyakov, V.D. 1991. Sootnosheniya 
Transuranovykh Elementov v 'Goryachikh' Chastitsakh, Vypavshikh v Rezultate 
Avarii v Blizhnei Zone ChaEs [Relationships of Transuranium Elements in 
HotParticles of the Fallout in the Near-Field Zone of the CHNPP. Problemy 
SelSkokhozyaistennoi Radiologii [Problems of Agricultural Radiology], Pages 45 
48. Kiev, Ukraine: Ukrainian Research Institute of Agricultural Radioecology. ACC: 
MOL.20000609.0007. 
125914 Louvat, D. and Davies, C., eds. 1998. Oklo Working Group: Proceedings of the 
First Joint EC-CEA Workshop on the Oklo-Natural Analogue Phase II Project Held 
in Sitjes, Spain, from 18 to 20 June 1997. EUR 18314 EN. Luxembourg, 
Luxembourg: Office for Official Publications of the European Communities. TIC: 
247709. 
157900 Lowry, W.E. 2001. Engineered Barrier Systems Thermal-Hydraulic-Chemical 
Column Test Report. TDR-EBS-MD-000018 REV 00. Las Vegas, Nevada: Bechtel 
SAIC Company. ACC: MOL.20020102.0206. 
100465 Luckey, R.R.; Tucci, P.; Faunt, C.C.; Ervin, E.M.; Steinkampf, W.C.; DAgnese, 
F.A.; and Patterson, G.L. 1996. Status of Understanding of the Saturated-Zone 
Ground-Water Flow System at Yucca Mountain, Nevada, as of 1995. Water- 
Resources Investigations Report 96-4077. Denver, Colorado: U.S. Geological 
Survey. ACC: MOL.19970513.0209. 
125923 Lutze, W.; Grambow, B.; Ewing, R.C.; and Jercinovic, M.J. 1987. The Use of 
Natural Analogues in the Long-Term Extrapolation of Glass Corrosion Processes. 
Natural Analogues in Radioactive Waste Disposal, Symposium held in Brussels on 
2830 April 1987. Cme, B. and Chapman, N.A., eds. EUR 11037 EN. Pages 142 
152. Norwell, Massachusetts: Graham & Trotman. TIC: 247254. 

154720 Macdonald, D.D. 1992. The Point Defect Model for the Passive State. Journal of 
the Electrochemical Society, 139, (12), 34343449. Manchester, New Hampshire: 
Electrochemical Society. TIC: 249804. 
156404 Magnuson, S.O. 1995. Inverse Modeling for Field-Scale Hydrologic and Transport 
Parameters of Fractured Basalt. INEL-95/0637. Idaho Falls, Idaho: Idaho National 
Engineering Laboratory, Lockheed Martin Idaho Technologies. TIC: 250952. 
156431 Magnuson, S.O. and Sondrup, A.J. 1998. Development, Calibration, and Predictive 
Results of a Simulator for Subsurface Pathway Fate and Transport of Aqueous- and 
Gaseous-Phase Contaminants in the Subsurface Disposal Area at the Idaho National 
Engineering and Environmental Laboratory. INEEL/EXT-97-00609. Idaho Falls, 
Idaho: Idaho National Engineering Laboratory. TIC: 251678. 
126058 Malow, G. and Ewing, R.C. 1981. Nuclear Waste Glasses and Volcanic Glasses: A 
Comparison of Their Stabilities. Scientific Basis for Nuclear Waste Management, 
Proceedings of the Third International Symposium, Boston, Massachusetts, 
November 1720, 1980. Moore, J.G., ed. 3, 315322. New York, New York: 
Plenum Press. TIC: 204407. 
154738 Marcus, P. and Maurice, V. 2000. Passivity of Metals and Alloys. Chapter 3 of 
Corrosion and Environmental Degradation. Schtze, M., ed. Volume I. Materials 
Science and Technology Volume 19. New York, New York: Wiley-VCH. TIC: 
249831. 
156449 Mariner, R.H. and Surdam, R.C. 1970. Alkalinity and Formation of Zeolites in 
Saline Alkaline Lakes. Science, 170, (3960), 977980. Washington, D.C.: 
American Association for the Advancement of Science. TIC: 250891. 
156811 Mariner, R.H. and Willey, L.M. 1976. Geochemistry of Thermal Waters in Long 
Valley, Mono County, California. Journal of Geophysical Research, 81, (5), 792 
800. Washington, D.C.: American Geophysical Union. TIC: 219144. 
156249 Marler, G.D. 1964. Effects of the Hebgen Lake Earthquake of August 17, 1959 on 
the Hot Springs of the Firehole Geyser Basins, Yellowstone National Park. 
Geological Survey Professional Paper 435-Q. Washington, D.C.: U.S. Governent 
Printing Office. TIC: 250923. 
151018 Marshall, B.D.; Neymark, L.A.; Paces, J.B.; Peterman, Z.E.; and Whelan, J.F. 2000. 
Seepage Flux Conceptualized from Secondary Calcite in Lithophysal Cavities in the 
Topopah Spring Tuff, Yucca Mountain, Nevada. SME Annual Meeting, February 
28March 1, 2000, Salt Lake City, Utah. Preprint 00-12. Littleton, Colorado: 
Society for Mining, Metallurgy, and Exploration. TIC: 248608. 
156432 Martian, P. 1995. UNSAT-H Infiltration Model Calibration at the Subsurface 
Disposal Area, Idaho National Engineering Laboratory. INEL-95/0596. Idaho Falls, 
Idaho: Idaho National Engineering Laboratory. TIC: 251842. 

100058 Matyskiela, W. 1997. Silica Redistribution and Hydrologic Changes in Heated 
Fractured Tuff. Geology, 25, (12), 11151118. Boulder, Colorado: Geological 
Society of America. TIC: 236809. 
156628 Mboulou, M.O.; Hurtgen, C.; Hofkens, K.; and Vandecasteele, C. 1998. Vertical 
Distributions in the Kapachi Soil of the Plutonium Isotopes (238Pu, 239,240Pu, 241Pu), of 
241Am, and of 243,244Cm, Eight Years After the Chernobyl Accident. Journal of 
Environmental Radioactivity, 39, (3), 231237. London, England: Elsevier. TIC: 
251075. 
157479 McCarthy, J.F. 1996. Natural Analogue Studies of the Role of Colloids, Natural 
Organics, and Microorganisms on Radionuclide Transport. Sixth EC Natural 
Analogue Working Group Meeting, Proceedings of an International Workshop held 
in Santa Fe, New Mexico, USA, on September 1216, 1994. von Maravic, H. and 
Smellie, J., eds. EUR 16761 EN. Pages 195210. Luxembourg, Luxembourg: 
Commission of the European Communities. TIC: 225227. 
110957 McConnell, K.I. and Lee, M.P. 1994. Staff Technical Position on Consideration of 
Fault Displacement Hazards in Geologic Repository Design. NUREG-1494. 
Washington, D.C.: U.S. Nuclear Regulatory Commission. TIC: 212360. 
157384 McCright, R.D.; Frey, W.F.; and Tardiff, G.E. 1980. Localized Corrosion of Steels 
in Geothermal Steam/Brine Mixtures. Geothermal Resources Council Transactions, 
4, 645648. Davis, California: Geothermal Resources Council. TIC: 251552. 
156433 McElroy, D.L. and Hubbell, J.M. 1990. Vadose Zone Monitoring at the 
Radioactive Waste Management Complex, Idaho National Engineering Laboratory. 
Proceedings of the Topical Meeting on Nuclear Waste Isolation in the Unsaturated 
Zone, FOCUS '89, September 1721, 1989, Las Vegas, Nevada. Pages 359364. La 
Grange Park, Illinois: American Nuclear Society. TIC: 212738. 
157486 McKinley, I.G. and Alexander, W.R. 1996. The Uses of Natural Analogue Input in 
Repository Performance Assessment: An Overview. Sixth EC Natural Analogue 
Working Group Meeting, Proceedings of an International Workshop Held in Santa 
Fe, New Mexico, USA on September 1216, 1994. von Maravic, H. and Smellie, J., 
eds. EUR 16761 EN, Pages 273282. Luxembourg, Luxembourg: Commission of 
the European Communities. TIC: 225227. 
126077 McKinley, I.G.; Bath, A.H.; Berner, U.; Cave, M.; and Neal, C. 1988. Results of 
the Oman Analogue Study. Radiochimica Acta, 44/45, (II), 311316. Mnchen, 
Germany: R. Oldenbourg Verlag. TIC: 247492. 
116222 McKinley, P.W.; Long, M.P.; and Benson, L.V. 1991. Chemical Analyses of Water 
from Selected Wells and Springs in the Yucca Mountain Area, Nevada and 
Southeastern California. Open-File Report 90-355. Denver, Colorado: U.S. 
Geological Survey. ACC: NNA.19901031.0004. 

101345 Meijer, A. 1987. Investigations of Natural Geologic and Geochemical Analogs in 
Relation to a Potential Nuclear Waste Repository at Yucca Mountain, Nevada. 
Milestone R398. Draft. Los Alamos, New Mexico: Los Alamos National 
Laboratory. ACC: NNA.19900112.0350. 
156670 Merritt, R.C. 1971. The Extractive Metallurgy of Uranium. Golden, Colorado: 
Colorado School of Mines Research Center. TIC: 251119. 
106762 Miekeley, N.; Couthinho de Jesus, H.; Porto da Silveira, C.L.; and Degueldre, C. 
1992. Chemical and Physical Characterization of Suspended Particles and Colloids 
in Waters from the Osamu Utsumi Mine and Morro do Ferro Analogue Study Sites, 
Poos-de-Caldas, Brazil. Journal of Geochemical Exploration, 45, 409437. 
Amsterdam, The Netherlands: Elsevier. TIC: 245687. 
127199 Miekeley, N.; Coutinho de Jesus, H.; Porto da Silveira, C.L.; and Degueldre, C. 
1991. Chemical and Physical Characterisation of Suspended Particles and Colloids 
in Waters from the Osamu Utsumi Mine and Morro do Ferro Analogue Study Sites, 
Pocos de Caldas, Brazil. SKB TR-90-18. Stockholm, Sweden: Svensk 
Krnbrnslefrsrjning A.B. TIC: 206355. 
126083 Miekeley, N.; Jesus, H.C.; Silveira, C.L.P.; and Kuechler, I.L. 1989. Colloid 
Investigations in the Pocos de Caldas Natural Analogue Project. Scientific Basis 
for Nuclear Waste Management XII, Symposium held October 1013, 1988, Berlin, 
Germany. Lutze, W. and Ewing, R.C., eds. 127, 831842. Pittsburgh, Pennsylvania: 
Materials Research Society. TIC: 203660. 
156458 Miller, D.M.; Miller, R.J.; Nielson, J.E.; Wilshire, H.G.; Howard, K.A.; and Stone, P. 
1991. Preliminary Geologic Map of the East Mojave National Scenic Area, 
California. Open-File Report 91-435. Menlo Park, California: U.S. Geological 
Survey. TIC: 251234. 
126089 Miller, W.; Alexander, R.; Chapman, N.; McKinley, I.; and Smellie, J. 1994. 
Natural Analogue Studies in the Geological Disposal of Radioactive Wastes. Studies 
in Environmental Science 57. New York, New York: Elsevier. TIC: 101822. 
156684 Miller, W.; Alexander, R.; Chapman, N.; McKinley, I.; and Smellie, J. 2000. 
Geologic Disposal of Radioactive Wastes & Natural Analogues, Lessons from Nature 
and Archaeology. Waste Management Series, Volume 2. New York, New York: 
Pergamon. TIC: 251762. 
157570 Mills, J.G., Jr.; Saltoun, B.W.; and Vogel, T.A. 1997. Magma Batches in the 
Timber Mountain Magmatic System, Southwestern Nevada Volcanic Field, Nevada, 
USA. Journal of Volcanology and Geothermal Research, 78, (34), 185208. 
Amsterdam, The Netherlands: Elsevier. TIC: 251831. 
156407 Molloy, M.W. 1981. Geothermal Reservoir Engineering Code Comparison 
Project. Proceedings, Special Panel on Geothermal Model Intercomparison Study, 
at the Sixth Workshop on Geothermal Reservoir Engineering, December 1618, 

1980. Workshop Report SGP-TR-42. Pages 126. Stanford, California: Stanford 
University. TIC: 250930. 
100161 Montazer, P. and Wilson, W.E. 1984. Conceptual Hydrologic Model of Flow in the 
Unsaturated Zone, Yucca Mountain, Nevada. Water-Resources Investigations Report 
84-4345. Lakewood, Colorado: U.S. Geological Survey. ACC: 
NNA.19890327.0051. 
156320 Moore, D.E.; Hickman, S.; Lockner, D.A.; and Dobson, P.F. 2001. Hydrothermal 
Minerals and Microstructures in the Silangkitang Geothermal Field Along the Great 
Sumatran Fault Zone, Sumatra, Indonesia. Geological Society of America Bulletin, 
113, (9), 11791192. Boulder, Colorado: Geological Society of America. TIC: 
250940. 
156318 Moore, J.N.; Adams, M.C.; and Anderson, A.J. 2000. The Fluid Inclusion and 
Mineralogic Record of the Transition from Liquid- to Vapor-Dominated Conditions 
in the Geysers Geothermal System, California. Economic Geology, 95, (8), 1719 
1737. Lancaster, Pennsylvania: Economic Geology Publishing. TIC: 250941. 
156319 Moore, J.N.; Lutz, S.J.; Renner, J.L.; McCulloch, J.; and Petty, S. 2000. Evolution 
of a Volcanic-Hosted Vapor-Dominated System: Petrologic and Geochemical Data 
from Corehole T-8, Karaha-Telaga Bodas, Indonesia. Geothermal Resources 
Council Transactions, 24, 259263. Davis, California: Geothermal Resources 
Council. TIC: 250942. 
157466 Mossop, A. and Segall, P. 1999. Volume Strain within The Geysers Geothermal 
Field. Journal of Geophysical Research, 104, (B12), Pages 29, 11329,131. 
Washington, D.C.: American Geophysical Union. TIC: 251646. 
154621 Mroczek, E.K. 1994. Review of Silica Deposition Rates at Ohaaki, Rotokawa and 
Wairakei Geothermal Fields and Comparison of Observed Rates with Predicted 
Deposition Rates Calculated Using Three Different Kinetic Deposition Models. 
Client Report 722305.15. Taupo, New Zealand: Institute of Geological & Nuclear 
Sciences Limited. TIC: 249770. 
156342 Mroczek, E.K. and McDowell, G. 1990. Silica Scaling Field Experiments. 1990 
International Symposium on Geothermal Energy, Transactions, Geothermal 
Resources Council, 1990 Annual Meeting, 2024 August, 1990, Kailua-Kona, 
Hawaii. Volume 14, Part II. Pages 16191625. Davis, California: Geothermal 
Resources Council. TIC: 246942. 
156360 Mroczek, E.K. and Reeves, R.R. 1994. The Effect of Colloidal Silica on Silica 
Scaling from Geothermal Fluid. Proceedings of the 16th New Zealand Geothermal 
Workshop, 1994. Soengkono, S. and Lee, K.C., eds. Pages 97101. Auckland, New 
Zealand: University of Auckland. TIC: 250972. 
156650 Muffler, L.J.P. and White, D.E. 1969. Active Metamorphism of Upper Cenozoic 
Sediments in the Salton Sea Geothermal Field and the Salton Trough, Southeastern 

California. Geological Society of America Bulletin, 80, 157182. Boulder, 
Colorado: Geological Society of America. TIC: 251080. 
156250 Muffler, L.J.P.; White, D.E.; and Truesdell, A.H. 1971. Hydrothermal Explosion 
Craters in Yellowstone National Park. Geological Society of America Bulletin, 82, 
(3), 723740. Boulder, Colorado: Geological Society of America. TIC: 250924. 
157494 Mumme, I. 1991. The Effect of Earthquakes on Underground Openings. Twenty 
Fifth Newcastle Symposium on Advances in the Study of the Sydney Basin, 12th to 
14th April, 1991, Newcastle, NSW Australia. Publication No. 413, Pages 7579. 
Newcastle, New South Wales, Australia: University of Newcastle, Department of 
Geology. TIC: 251869. 
157487 Murphy, W.M. 2000. Natural Analogs and Performance Assessment for Geologic 
Disposal of Nuclear Waste. Scientific Basis for Nuclear Waste Management XXIII, 
Symposium Held November 29December 2, 1999, Boston, Massachusetts. Smith, 
R.W. and Shoesmith, D.W., eds. 608, 533544. Warrendale, Pennsylvania: 
Materials Research Society. TIC: 249052. 
149529 Murphy, W.M. and Codell, R.B. 1999. Alternate Source Term Models for Yucca 
Mountain Performance Assessment Based on Natural Analog Data and Secondary 
Mineral Solubility. Scientific Basis for Nuclear Waste Management XXII, 
Symposium held November 30December 4, 1998, Boston, Massachusetts. 
Wronkiewicz, D.J. and Lee, J.H., eds. 556, 551558. Warrendale, Pennsylvania: 
Materials Research Society. TIC: 246426. 
156612 Murray, L.E.; Rohrs, D.T.; Rossknecht, T.G.; Aryawijaya, R.; and Pudyastuti, K. 
1995. Resource Evaluation and Development Strategy, Awibengkok Field. 
Proceedings of the World Geothermal Congress 1995, Florence, Italy, May 1831, 
1995. Barbier, E.; Frye, G.; Iglesias, E.; and Plmason, G.; eds. 5, 15251529. 
Auckland, New Zealand: International Geothermal Association. TIC: 251065. 
168484 Murrell, M.T., Goldstein, S.J. and Dixon, P.R. 2002. Uranium Decay Series 
Mobility at Pea Blanca, Mexico: Implications for Nuclear Repository Stability. 
Nuclear Science and Technology, 8th EC Natural Analogue Working Group Meeting, 
Strasbourg, France, March 2325, 1999. von Maravic, H. and Alexander, W.R., eds. 
EUR 19118, 339347. Luxembourg, Luxembourg: Office for Official Publications of 
the European Communities. 
156365 Nakata, E.; Chigira, M.; and Watanabe, M. 1998. Transformation of Diatomite into 
Porcelanite and Opaline Chert under the Influence of an Andesite Intrusion in the 
Miocene Iwaya Formation, Japan. Water-Rock Interaction, Proceedings of the 
International Symposium on Water-Rock Interaction, WRI-9, Taupo, New Zealand, 
30 March3 April 1998. Arehart, G.B. and Hulston, J.R., eds. Pages 333336. 
Brookfield, Vermont: A.A. Balkema. TIC: 250944. 

100061 National Research Council. 1990. Rethinking High-Level Radioactive Waste 
Disposal, A Position Statement of the Board on Radioactive Waste Management. 
Washington, D.C.: National Academy Press. TIC: 205153. 
126123 Naudet, R. 1978. Etude Parametrique de la Criticite des Reacteurs Naturels. Les 
Reacteurs de Fission Naturels, Natural Fission Reactors. Proceedings of a Meeting 
on the Technical Committee on Natural Fission Reactors, Paris, 19 to 21 December 
1977. Pages 589599. Vienna, Austria: International Atomic Energy Agency. TIC: 
247910. 
156632 NEA (Nuclear Energy Agency). 1995. Chernobyl, Ten Years On, Radiological and 
Health Impact. Paris, France: Organisation for Economic Co-operation and 
Development. Accessed December 19, 2001. TIC: 251078. 
http://www.nea.fr/html/rp/chernobyl/ 
150092 Nelson, P.H.; Rachiele, R.; Remer, J.S.; and Carlsson, H. 1981. Water Inflow into 
Boreholes during the Stripa Heater Experiments. LBL-12574. Berkeley, California: 
Lawrence Berkeley Laboratory. TIC: 228851. 
156221 Neumayer, E. 1983. Prehistoric Indian Rock Paintings. New Dehli, India: Oxford 
University Press. TIC: 250805. 
156434 Newman, M.E.; Porro, I.; Scott, R.; Dunnivant, F.M.; Goff, R.W.; Blevins, M.D.; 
Ince, S.M.; Leyba, J.D.; DeVol, T.A.; Elzerman, A.W.; and Fjeld, R.A. 1995. 
Evaluation of the Mobility of Am, Cs, Co, Pu, Sr, and U through INEL Basalts and 
Interbed Materials: Summary Report of the INEL/Clemson University Laboratory 
Studies. WAG7-82, INEL-95/282. Clemson, South Carolina: Clemson University, 
Enviromental Systems Engineering, Rich Labs. TIC: 251897. 
154458 Nimmo, J.R.; Perkins, K.S.; Rose, P.E.; Rousseau, J.P.; Orr, B.R.; Twining, B.V.; and 
Anderson, S.R. 2001. Kilometer-Scale Rapid Flow in a Fractured-Basalt 
Unsaturated Zone at the Idaho National Engineering and Environmental Laboratory. 
Fractured Rock 2001, An International Conference Addressing Groundwater Flow, 
Solute Transport, Multiphase Flow, and Remediation in Fractured Rock, March 26 
28, 2001, Toronto, Ontario, Canada. Kueper, B.H.; Novakowski, K.S.; and 
Reynolds, D.A., eds. Smithville, Ontario, Canada: Smithville Phase IV. TIC: 
249909. 
117880 Nitao, J.J. 1998. Thermohydrochemical Alteration of Flow Pathways above and 
below the Repository. Chapter 5.6 of Near-Field/Altered-Zone Models Report. 
Hardin, E.L. UCRL-ID-129179 DR. Livermore, California: Lawrence Livermore 
National Laboratory. ACC: MOL.19980504.0577. 
156637 Norris, R.M. 1999. Geologic Setting of Mitchell Caverns. Pages 314. Sacramento, 
California: California State Parks TIC: 251426. 
151592 NRC (U.S. Nuclear Regulatory Commission). 1999. Issue Resolution Status Report 
Key Technical Issue: Igneous Activity. Rev. 2. Washington, D.C.: U.S. Nuclear 

Regulatory Commission. Accessed September 18, 2000. TIC: 247987. 
http://www.nrc.gov/NMSS/DWM/ia-rev2.htm 
163274 NRC (U.S. Nuclear Regulatory Commission) 2003. Yucca Mountain Review Plan, 
Final Report. NUREG-1804, Rev. 2. Washington, D.C.: U.S. Nuclear Regulatory 
Commission, Office of Nuclear Material Safety and Safeguards. TIC: 254568. 
126162 NWTRB (Nuclear Waste Technical Review Board) 1990. Second Report to the U.S. 
Congress and the U.S. Secretary of Energy. Washington, D.C.: Nuclear Waste 
Technical Review Board. ACC: HQX.19901214.0061. 
157447 Nyhan, J.W.; Drennon, B.J.; Abeele, W.V.; Wheeler, M.L.; Purtymun, W.D.; Trujillo, 
G.; Herrera, W.J.; and Booth, J.W. 1985. Distribution of Plutonium and Americium 
beneath a 33-yr-old Liquid Waste Disposal Site. Journal of Environmental Quality, 
14, (4), 501509. Madison, Wisconsin: American Society of Agronomy. TIC: 
218692. 
154567 OSullivan, M.J.; Bullivant, D.P.; Follows, S.E.; and Mannington, W.I. 1998. 
Modelling of the Wairakei-Tauhara Geothermal System. Proceedings of the 
TOUGH Workshop '98, Berkeley, California, May 46, 1998. Pruess, K., ed. 
LBNL-41995. Pages 16. Berkeley, California: Lawrence Berkeley National 
Laboratory. TIC: 247159. 
156353 OSullivan, M.J.; Pruess, K.; and Lippmann, M.J. 2001. State of the Art of 
Geothermal Reservoir Simulation. Geothermics, 30, (4), 395429. New York, New 
York: Elsevier. TIC: 250945. 
100069 Oliver, T. and Root, T. 1997. Hydrochemical Database for the Yucca Mountain 
Area, Nye County, Nevada. Denver, Colorado: U.S. Geological Survey. ACC: 
MOL.19980302.0367. 
100485 Oversby, V.M. 1996. Criticality in a High Level Waste Repository, A Review of 
Some Important Factors and an Assessment of the Lessons That Can Be Learned 
from the Oklo Reactors. SKB TR-96-07. Stockholm, Sweden: Svensk 
Krnbrnslefrsrjning A.B. TIC: 226156. 
155058 Ozment, K. 1999. Journey to the Copper Age. National Geographic, 195, (4), 70 
79. Washington, D.C.: National Geographic Society. TIC: 249913. 
107408 Paces, J.B.; Neymark, L.A.; Marshall, B.D.; Whelan, J.F.; and Peterman, Z.E. 1998. 
Inferences for Yucca Mountain Unsaturated-Zone Hydrology from Secondary 
Minerals. High-Level Radioactive Waste Management, Proceedings of the Eighth 
International Conference, Las Vegas, Nevada, May 1114, 1998. Pages 3639. La 
Grange Park, Illinois: American Nuclear Society. TIC: 237082. 
124806 Papp, Z.; Bolyos, A.; Dezso. Z; and Daroczy, S. 1997. Direct Determination of 90Sr 
and 147Pm in Chernobyl Hot Particles Collected in Kiev Using Beta Absorption 

Method. Health Physics, 73, (6), 944952. Baltimore, Maryland: Williams and 
Wilkins. TIC: 247152. 
126526 Parker, J.C. and van Genuchten, M. Th. 1984. Determining Transport Parameters 
from Laboratory and Field Tracer Experiments. Virginia Agricultural Experiment 
Station. Bulletin 84-3. Blacksburg, Virginia: Virginia Polytechnic Institute and State 
University. TIC: 223781. 
124812 Payne, T.E.; Edis, R.; and Seo, T. 1992. Radionuclide Transport by Groundwater 
Colloids at the Koongarra Uranium Deposit. Scientific Basis for Nuclear Waste 
Management XV, Symposium Held November 47, 1991, Strasbourg, France. 
Sombret, C.G., ed. 257, 481488. Pittsburgh, Pennsylvania: Materials Research 
Society. TIC: 204618. 
149523 Pearcy, E.C. 1994. Fracture Transport of Uranium at the Nopal I Natural Analog 
Site. CNWRA 94-011. San Antonio, Texas: Center for Nuclear Waste Regulatory 
Analyses. TIC: 247808. 
157563 Pearcy, E.C. and Murphy, W.M. 1991. Geochemical Natural Analogs. Chapter 7 
of Report on Research Activities for Calendar Year 1990. Patrick, W.C., ed. 
NUREG/CR-5817. Washington, D.C.: U.S. Nuclear Regulatory Commission. TIC: 
208964. 
110223 Pearcy, E.C.; Prikryl, J.D.; and Leslie, B.W. 1995. Uranium Transport Through 
Fractured Silicic Tuff and Relative Retention in Areas with Distinct Fracture 
Characteristics. Applied Geochemistry, 10, 685-704. Oxford, United Kingdom: 
Elsevier. TIC: 246848. 
100486 Pearcy, E.C.; Prikryl, J.D.; Murphy, W.M.; and Leslie, B.W. 1994. Alteration of 
Uraninite from the Nopal I Deposit, Pea Blanca District, Chihuahua, Mexico, 
Compared to Degradation of Spent Nuclear Fuel in the Proposed U.S. High-Level 
Nuclear Waste Repository at Yucca Mountain, Nevada. Applied Geochemistry, 9, 
713732. New York, New York: Elsevier Science. TIC: 236934. 
156822 Perepelyatnikov, G.P.; Prister, B.S.; and Sobolev, A.S. 1991. Migratiya 
radionuklidov v sisteme voda-pochva-rastenie na ugod'yakh oroshaemykh vodoi reki 
Dnepr posle avarii na ChAES (Migration of radionuclides in the system water-soilplant 
on lands irrigated using Dnieper water after the ChNPP accident). In: 
Problemy Sel'skokhozyaistennoi Radiologii (Problems of Agricultural Radiology). 
Pages 106112. Kiev, Ukraine: Ukrainian Research Institute of Agricultural 
Radioecology. 
101053 Perfect, D.L.; Faunt, C.C.; Steinkampf, W.C.; and Turner, A.K. 1995. 
Hydrochemical Data Base for the Death Valley Region, California and Nevada. 
Open-File Report 94-305. Denver, Colorado: U.S. Geological Survey. ACC: 
MOL.19940718.0001. 

144335 Perry, F.V.; Crowe, B.M.; Valentine, G.A.; and Bowker, L.M., eds. 1998. Volcanism 
Studies: Final Report for the Yucca Mountain Project. LA-13478. Los Alamos, New 
Mexico: Los Alamos National Laboratory. TIC: 247225. 
121957 Peters, R.R.; Klavetter, E.A.; Hall, I.J.; Blair, S.C.; Heller, P.R.; and Gee, G.W. 
1984. Fracture and Matrix Hydrologic Characteristics of Tuffaceous Materials from 
Yucca Mountain, Nye County, Nevada. SAND84-1471. Albuquerque, New Mexico: 
Sandia National Laboratories. ACC: NNA.19900810.0674. 
105743 Philip, J.R.; Knight, J.H.; and Waechter, R.T. 1989. Unsaturated Seepage and 
Subterranean Holes: Conspectus, and Exclusion Problem for Circular Cylindrical 
Cavities. Water Resources Research, 25, (1), 1628. Washington, D.C.: American 
Geophysical Union. TIC: 239117. 
110009 Pickett, D.A. and Murphy, W.M. 1999. Unsaturated Zone Waters from the Nopal I 
Natural Analog, Chihuahua, MexicoImplications for Radionuclide Mobility at 
Yucca Mountain. Scientific Basis for Nuclear Waste Management XXII, Symposium 
held November 30December 4, 1998, Boston, Massachusetts. Wronkiewicz, D.J. 
and Lee, J.H., eds. 556, 809816. Warrendale, Pennsylvania: Materials Research 
Society. TIC: 246426. 
168525 Pickett, D.A., Prikryl, J.D., Murphy, W.M., and Pearcy, E.C. 1996. Uranium-series 
Disequilibrium Investigation of Radionuclide Mobility at the Nopal I Uranium 
Deposit, Pea Blanca District, Mexico: Implications for Episodic Radionuclide 
Transport at a Geologic Repository for High-level Nuclear Waste. Eos, 
Transactions, [Supplement 77], S94. Washington, D.C.: American Geophysical 
Union. 
156638 Pinto, D.G. 1989. The Archeology of Mitchell Caverns. California Archeological 
Reports, No. 25. Pages 1110. Sacramento, California: State of California, 
Department of Parks and Recreation. TIC: 251467. 
156159 Polyak, V.J.; McIntosh, W.C.; Gven, N.; and Provencio, P. 1998. Age and Origin 
of Carlsbad Cavern and Related Caves from 40Ar/ 39Ar of Alunite. Science, 279, 
(5358), 19191922. Washington, D.C.: American Association for the Advancement 
of Science. TIC: 250925. 
168458 Porcelli D. and Swarzenski P.W. 2003. The Behavior of U- and Th-series Nuclides 
in Groundwater. Reviews in Mineralogy and Geochemistry. Volume 52. Bourdon, 
B.; Henderson, G.M.; Lundstrom, C.C.; and Turner, S.P., Eds. Pages 317361. 
Washington, D.C.: Mineralogical Society of America. TIC: 256055. 
157523 Power, M.S.; Rosidi, D.; and Kaneshiro, J.Y. 1998. Seismic Vulnerability of 
Tunnels and Underground Structures Revisited. North American Tunneling '98, 
Proceedings of the North American Tunneling '98 Conference, Newport Beach, 
California, USA, 2125, February 1998. Rotterdam, The Netherlands: A.A. 
Balkema. TIC: 251801. 

157503 Poyarkov, V. 2000. Introduction. Chapter 1 of The Chornobyl Accident, A 
Comprehensive Risk Assessment. Vargo, G.J., ed. Columbus, Ohio: Battelle Press. 
TIC: 251266. 
151817 Pratt, H.R.; Hustrulid, W.A.; and Stephenson, D.E. 1978. Earthquake Damage to 
Underground Facilities. DP-1513. Aiken, South Carolina: E.I. du Pont de Nemours 
and Company, Savannah River Laboratory. TIC: 210276. 
100413 Pruess, K. 1991. TOUGH2A General-Purpose Numerical Simulator for 
Multiphase Fluid and Heat Flow. LBL-29400. Berkeley, California: Lawrence 
Berkeley Laboratory. ACC: NNA.19940202.0088. 
101707 Pruess, K. and Narasimhan, T.N. 1985. A Practical Method for Modeling Fluid and 
Heat Flow in Fractured Porous Media. Society of Petroleum Engineers Journal, 25, 
(1), 1426. Dallas, Texas: Society of Petroleum Engineers. TIC: 221917. 
157385 Pye, D.S.; Holligan, D.; Cron, C.J.; and Love, W.W. 1989. The Use of Beta-C 
Titanium for Downhole Production Casing in Geothermal Wells. Geothermics, 18, 
(1/2), 259267. New York, New York: Pergamon Press. TIC: 251554. 
156640 Quindos, L.S.; Bonet, A.; Diaz-Caneja, N.; Fernandez, P.L.; Gutierrez, I.; Solana, 
J.R.; Soto, J.; and Villar, E. 1987. Study of the Environmental Variables Affecting 
the Natural Preservation of the Altamira Cave Paintings Located at Santillana Del 
Mar, Spain. Atmospheric Environment, 21, (3), 551560. New York, New York: 
Pergamon Press. TIC: 251037. 
156450 Quinlivan, W.D. and Byers, F.M., Jr. 1977. Chemical Data and Variation Diagrams 
of Igneous Rocks from the Timber Mountain-Oasis Valley Caldera Complex, 
Southern Nevada. Open File Report 77-724. Boulder, Colorado: U.S. Geological 
Survey. ACC: NNA.19890303.0035. 
106634 Ratcliff, C.D.; Geissman, J.W.; Perry, F.V.; Crowe, B.M.; and Zeitler, P.K. 1994. 
Paleomagnetic Record of a Geomagnetic Field Reversal from Late Miocene Mafic 
Intrusions, Southern Nevada. Science, 266, 412416. Washington, D.C.: American 
Association for the Advancement of Science. TIC: 234818. 
156439 Rawson, S.A.; Walton, J.C.; and Baca, R.G. 1991. Migration of Actinides from a 
Transuranic Waste Disposal Site in the Vadose Zone. Radiochimica Acta, 52/53, 
477486. Mnchen, Germany: R. Oldenbourg Verlag. TIC: 251669. 
168028 Reyes-Corts, I.A. 2002. Geologic Setting and Mineralisation: Sierra Pea Blanca, 
Chihuahua, Mxico. Eighth EC Natural Analogue Working Group Meeting, 
Proceedings of an International Workshop held in Strasbourg, France from 23 to 25 
March 1999. von Maravic, H. and Alexander, W.R., eds. EUR 19118 EN. Pages 
321-331. Luxembourg, Luxembourg: Office for Official Publications of the 
European Communities. TIC: 255689. 

157613 Richards, J.I. and Hance, R.J. 1996. Agricultural Countermeasures. Chernobyl. 
Vienna, Austria: International Atomic Energy Agency. Accessed June 24, 2003. 
TIC: 251880. http://www.iaea.org/worldatom/Periodicals/Bulletin/Bull383/ 
156442 Rightmire, C.T. and Lewis, B.D. 1988. Influence of the Geochemical Environment 
on Radionuclide Migration in the Unsaturated Zone, Radioactive Waste Management 
Complex, Idaho National Engineering Laboratory, Idaho. U.S. Geological Survey 
Open-File Report 95-. Idaho Falls, Idaho: Idaho National Engineering Laboratory. 
156440 Rightmire, C.T. and Lewis, B.D. 1987. Geologic Data Collected and Analytical 
Procedures Used During a Geochemical Investigation of the Unsaturated Zone, 
Radioactive Waste Management Complex, Idaho National Engineering Laboratory, 
Idaho. Open-File Report 87-246. Idaho Falls, Idaho: U.S. Geological Survey. TIC: 
251805. 
156441 Rightmire, C.T. and Lewis, B.D. 1987. Hydrogeology and Geochemistry of the 
Unsaturated Zone, Radioactive Waste Management Complex, Idaho National 
Engineering Laboratory, Idaho. DOE/ID-22073. Idaho Falls, Idaho: U.S. 
Department of Energy. TIC: 251843. 
101708 Rimstidt, J.D. and Barnes, H.L. 1980. The Kinetics of Silica-Water Reactions. 
Geochimica et Cosmochimica Acta, 44, 16831699. New York, New York: 
Pergamon Press. TIC: 219975. 
142190 Rimstidt, J.D.; Newcomb, W.D.; and Shettel, D.L., Jr. 1989. A Vertical Thermal 
Gradient Experiment to Simulate Conditions in Vapor Dominated Geothermal 
Systems, Epithermal Gold Deposits, and High Level Radioactive Repositories in 
Unsaturated Media. Proceedings of the 6th International Symposium on Water-Rock 
Interaction, WRI-6, Malvern, United Kingdom, 38 August 1989. Miles, D.L., ed. 
Pages 585588. Rotterdam, The Netherlands: A.A. Balkema. TIC: 241868. 
126287 Rivas, P.; Hernan, P.; Astudillo, J.; Bruno, J.; Carrerra, J.; De la Cruz, B.; Guimera, 
J.; Gomez, P.; Ivanovich, M.; Marin, C.; Miller, W.; and Perez del Villar, L. 1998. 
Nuclear Science and Technology, El Berrocal Project. EUR 17830 EN. 
Luxembourg, Luxembourg: Commission of European Communities. TIC: 247318. 
100416 Robinson, B.A.; Wolfsberg, A.V.; Viswanathan, H.S.; Bussod, G.Y.; Gable, C.W.; 
and Meijer, A. 1997. The Site-Scale Unsaturated Zone Transport Model of Yucca 
Mountain. Milestone SP25BM3. Los Alamos, New Mexico: Los Alamos National 
Laboratory. ACC: MOL.19980203.0570. 
157445 Robinson, R.A. 1985. Summary of Results and Conclusions from the Cooperative 
Project at Stripa between Sweden and the United States during 19771980. 
Proceedings of the Symposium on In Situ Experiments in Granite Associated with the 
Disposal of Radioactive Waste, International Stripa Project, Stockholm, Sweden, 46 
June 1985. Paris, France: Nuclear Energy Agency, Organization for Economic Cooperation 
and Development. TIC: 251879. 

157386 Robles-Camacho, J. and Armienta, M.A. 2000. Natural Chromium Contamination 
of Groundwater at Len Valley, Mxico. Journal of Geochemical Exploration, 68, 
(3), 167181. New York, New York: Elsevier. TIC: 251555. 
154320 Rogers, K.L.; Repenning, C.A.; Luiszer, F.G.; and Benson, R.D. 2000. Geologic 
History, Stratigraphy, and Paleontology of SAM Cave, North-Central New Mexico. 
New Mexico Geology, 22, (4), 89100. Socorro, New Mexico: New Mexico Bureau 
of Mines and Mineral Resources. TIC: 249818. 
157573 Romero, L.; Neretnieks, I.; and Moreno, L. 1992. Movement of the Redox Front at 
the Osamu Utsumi Uranium Mine, Pocos de Caldas, Brazil. Journal of 
Geochemical Exploration, 45, (13), 471502. Amsterdam, The Netherlands: 
Elsevier. TIC: 251833 
156341 Rose, P.E.; Benoit, W.R.; and Adams, M.C. 1998. Tracer Testing at Dixie Valley, 
Nevada, Using Pyrene Tetrasulfonate, Amino G, and Fluorescein. Geothermal 
Resources Council Transactions, 22, 583587. Davis, California: Geothermal 
Resources Council. TIC: 250946. 
154862 Rosenberg, N.D.; Gdowski, G.E.; and Knauss, K.G. 2001. Evaporative Chemical 
Evolution of Natural Waters at Yucca Mountain, Nevada. Applied Geochemistry, 
16, (910), 12311240. New York, New York: Pergamon. TIC: 249879. 
156629 Rosner, G. and Winkler, R. 2001. Long-Term Variation (19861998) of Post- 
Chernobyl 90Sr, 137Cs, 238Pu and 239,240Pu Concentrations in Air, Depositions to 
Ground, Resuspension Factors, and Resuspension Rates in South Germany. The 
Science of the Total Environment, 273, (13), 1125. New York, New York: 
Elsevier. TIC: 251076. 
102097 Rousseau, J.P.; Kwicklis, E.M.; and Gillies, D.C., eds. 1999. Hydrogeology of the 
Unsaturated Zone, North Ramp Area of the Exploratory Studies Facility, Yucca 
Mountain, Nevada. Water-Resources Investigations Report 98-4050. Denver, 
Colorado: U.S. Geological Survey. ACC: MOL.19990419.0335. 
156223 Ruspoli, M. 1987. The Cave of Lascaux, The Final Photographs. New York, New 
York: Harry N. Abrams. TIC: 250806. 
157316 Salve, R. and Oldenburg, C.M. 2001. Water Flow within a Fault in Altered 
Nonwelded Tuff. Water Resources Research, 37, (12), 30433056. Washington, 
D.C.: American Geophysical Union. TIC: 251485. 
156848 Salve, R.; Hudson, D.; and Cook, P. 2001. Investigation of Flow along a Vertical 
Fault: Field Techniques. Eos, Transactions (Supplement), 82, (47), F382. 
Washington, D.C.: American Geophysical Union. TIC: 251282. 
157382 Snchez-Moral, S.; Soler, V.; Caaveras, J.C.; Sanz-Rubio, E.; Van Grieken, R.; and 
Gysels, K. 1999. Inorganic Deterioration Affecting the Altamira Cave, N Spain: 
Quantitative Approach to Wall-Corrosion (Solutional Etching) Processes Induced by 

Visitors. The Science of the Total Environment, 243/244, 6784. New York, New 
York: Elsevier. TIC: 251550. 
157465 Sasaki, S. 1998. Characteristics of Microseismic Events Induced during Hydraulic 
Fracturing Experiments at the Hijiori Hot Dry Rock Geothermal Energy Site, 
Yamagata, Japan. Tectonophysics, 289, (13), 171188. Amsterdam, The 
Netherlands: Elsevier. TIC: 251882. 
148612 Savino, J.M.; Smith, K.D.; Biasi, G.; Sullivan, T.; and Cline, M. 1999. Earthquake 
Ground Motion Effects on Underground Structures/Tunnels. Eos, Transactions 
(Supplement), 80, (17), S10. Washington, D.C.: American Geophysical Union. TIC: 
247757. 
100075 Sawyer, D.A.; Fleck, R.J.; Lanphere, M.A.; Warren, R.G.; Broxton, D.E.; and 
Hudson, M.R. 1994. Episodic Caldera Volcanism in the Miocene Southwestern 
Nevada Volcanic Field: Revised Stratigraphic Framework, 40Ar/39Ar Geochronology, 
and Implications for Magmatism and Extension. Geological Society of America 
Bulletin, 106, (10), 13041318. Boulder, Colorado: Geological Society of America. 
TIC: 222523. 
156641 Schick, T. 1998. The Cave of the Warrior, A Fourth Millennium Burial in the 
Judean Desert. IAA Reports, No. 5. Jerusalem, Israel: Israel Antiquities Authority. 
TIC: 251260. 
154644 Schiffman, P.; Bird, D.K.; and Elders, W.A. 1985. Hydrothermal Mineralogy of 
Calcareous Sandstones from the Colorado River Delta in the Cerro Prieto Geothermal 
System, Baja California, Mexico. Mineralogical Magazine, 49, (Part 3), 435449. 
London, England: Mineralogical Society. TIC: 249764. 
101156 Scott, R.B.; Spengler, R.W.; Diehl, S.; Lappin, A.R.; and Chornack, M.P. 1983. 
Geologic Character of Tuffs in the Unsaturated Zone at Yucca Mountain, Southern 
Nevada. Role of the Unsaturated Zone in Radioactive and Hazardous Waste 
Disposal, May 31June 4, 1982, Philadelphia, Pennsylvania. Mercer, J.W.; Rao, 
P.S.C.; and Marine, I.W., eds. Pages 289335. Ann Arbor, Michigan: Ann Arbor 
Science Publishers. TIC: 245124. 
157464 Segall, P. and Fitzgerald, S.D. 1998. A Note on Induced Stress Changes in 
Hydrocarbon and Geothermal Reservoirs. Tectonophysics, 289, (13), 117128. 
Amsterdam, The Netherlands: Elsevier. TIC: 251894. 
157480 Seo, T.; Edis, R.; and Payne, T.E. 1994. A Study of Colloids in Groundwaters at 
the Koongarra Uranium Deposit. Fifth CEC Natural Analogue Working Group 
Meeting and Alligator Rivers Analogue Project (ARAP) Final Workshop, 
Proceedings of an International Workshop, Held in Toledo, Spain, from 5 to 9 
October 1992. von Maravic, H. and Smellie, J., eds. EUR 15176 EN, Pages 7176. 
Luxembourg, Luxembourg: Commission of the European Communities. TIC: 
247923. 

154505 Sharma, S. and Judd, W.R. 1991. Underground Opening Damage from 
Earthquakes. Engineering Geology, 30, (3/4), 263276. Amsterdam, The 
Netherlands: Elsevier. TIC: 226268. 
156673 Shea, M. 1984. Uranium Migration at Some Hydrothermal Veins Near Marysvale, 
Utah: A Natural Analog for Waste Isolation. Scientific Basis for Nuclear Waste 
Management VII, Symposium held November 1417, 1983, Boston, Massachusetts, 
U.S.A. McVay, G.L., ed. 26, 227238. New York, New York: Elsevier. TIC: 
204393. 
156672 Shea, M. and Foland, K.A. 1986. The Marysvale Natural Analog Study: 
Preliminary Oxygen Isotope Relations. Chemical Geology, 55, 281295. 
Amsterdam, The Netherlands: Elsevier. TIC: 251138. 
157425 Shepherd, R. 1993. Ancient Mining. 494 pages. New York, New York: Elsevier. 
Out of Print/Out of Stock. 
156451 Sheppard, R.A. 1993. Geology and Diagenetic Mineralogy of the Castle Creek 
Zeolite Deposit and the Ben-Jel Bentonite Deposit, Chalk Hills Formation, Oreana, 
Idaho. Zeo-Trip '93, An Excursion to Selected Zeolite and Clay Deposits in 
Southeastern Oregon and Southwestern Idaho, June 2628, 1993. Mumpton, F.A., 
ed. Pages 113. Brockport, New York: International Committee on Natural Zeolites. 
TIC: 251008. 
157507 Shestopalov, V. and Poyarkov, V. 2000. Environmental Contamination. Chapter 
5 of The Chornobyl Accident: A Comprehensive Risk Assessment. Vargo, G.J., ed. 
Columbus, Ohio: Battelle Press. TIC: 251266. 
107844 Shestopalov, V.M. 1996. Atlas of Chernobyl Exclusion Zone. Kiev, Ukraine: 
Kartohrafiia. TIC: 248100. 
126508 Silant'ev, A.N.; Shkuratova, I.G.; and Bobovnikova, Ts.I. 1989. Vertical Soil 
Migration of Radionuclide Fallout from the Chernobyl' Accident. Translated from 
Atomnaya Energiya [Soviet Atomic Energy], 66, (3), 221225. New York, New 
York: Plenum Publishing. TIC: 247772. 
157578 Simmons, A.M. 2002. Scientific Notebooks Referenced in the Natural Analogue 
Synthesis Report, TDR-NBS-GS-000027 REV00. Interoffice correspondence from 
A.M. Simmons (BSC) to File, February 14, 2002, with attachments. ACC: 
MOL.20020311.0230. 
169270 Simmons, A.M. 2004. Scientific Notebooks Referenced in the Natural Analogue 
Synthesis Report, TDR-NBS-GS-000027 REV 01. Interoffice correspondence from 
A.M. Simmons (BSC) to File, May 14, 2004, with attachments. ACC: 
MOL.20040512.0309 through MOL.20040512.0311. 

157544 Simmons, A.M. 2002. Natural Analogues. Scientific Notebook YMP-LBNL-AMSNA-
1. ACC: MOL.19990927.0459; MOL.20000817.0316; MOL.20010713.0016; 
MOL.20020204.0265. 
126511 Simmons, A.M. and Bodvarsson, G.S. 1997. Building Confidence in 
Thermohydrologic Models of Yucca Mountain Using Geothermal Analogues. 
Milestone SPLE1M4. Berkeley, California: Lawrence Berkeley National Laboratory. 
ACC: MOL.19970710.0328. 
168568 Simmons, A.M.; Murrell, M.T.; and Goldstein, S.J. 2002. Seasonal Fluctuation in 
Uranium Decay-Series Composition of Waters at Pea Blanca, Mexico. Abstracts 
with Programs - Geological Society of America, 34, (6), 235. Boulder, Colorado: 
Geological Society of America. TIC: 254868. 
126633 Smellie, J.A.T., ed. 1998. MAQARIN Natural Analogue Study: Phase III. SKB TR- 
98-04. Two volumes. Stockholm, Sweden: Svensk Krnbrnslefrsrjning A.B. 
TIC: 244013. 
126636 Smellie, J.; Chapman, N.; McKinley, I.; Penna Franca, E.; and Shea, M. 1989. 
Testing Safety Assessment Models Using Natural Analogues in High Natural-Series 
Groundwaters. The Second Year of the Pocos de Caldas Project. Scientific Basis 
for Nuclear Waste Management XII, Symposium held October 1013, 1988, Berlin, 
Germany. Lutze, W. and Ewing, R.C., eds. 127, 863870. Pittsburgh, Pennsylvania: 
Materials Research Society. TIC: 203660. 
126645 Smellie, J.A.T.; Winberg, A.; and Karlsson, F. 1993. Swedish Activities in the 
Oklo Natural Analogue Project. 2nd Joint CEC-CEA Progress Meeting of the Oklo 
Working Group, Brussels, Belgium, April 67, 1992. von Maravic, H., ed. EUR 
14877 EN. Pages 131142. Luxembourg, Luxembourg: Commission of the 
European Communities. TIC: 247581. 
156906 Smith, J.T.; Comans, R.N.J.; Beresford, N.A.; Wright, S.M.; Howard, B.J.; and 
Camplin, W.C. 2000. Pollution, Chernobyls Legacy in Food and Water. Nature, 
405, (6782), 141. London, England: Macmillan Journals. TIC: 251283. 
157433 Smith, J.T.; Kudelsky, A.V.; Ryabov, I.N.; and Hadderingh, R.H. 2000. 
Radiocaesium Concentration Factors of Chernobyl-Contaminated Fish: A Study of 
the Influence of Potassium, and Blind Testing of a Previously Developed Model. 
Journal of Environmental Radioactivity, 48, 359369. New York, New York: 
Elsevier. TIC: 251582. 
134218 Sobotovich, E.V. 1992. Radiogeokhimiia v Zone Vliianiia ChernobylSkoi AES 
(Radiogeochemistry of the Zone of Influence of Chernobyl NPP). Kiev, Naukova 
Dumka, Ukraine: Academy of Sciences of Ukraine. ACC: MOL.20000629.0589. 
156821 Sobotovich, E.V. and Dolin, V.V. 1994. Mechanism of Accumulation of Migration 
Forms of 137Cs and 90Sr in Soils of the Near-Field Zone of CHNPP. Problems of 
Chernobyl Exclusion Zone. Volume 1. Pages 5560. Chernobyl, Ukraine: 

Administration of the Chernobyl Exclusion Zone. Copyright Requested Library 
Tracking Number-251862. 
117127 Sonnenthal, E.L. and Bodvarsson, G.S. 1999. Constraints on the Hydrology of the 
Unsaturated Zone at Yucca Mountain, NV, from Three-Dimensional Models of 
Chloride and Strontium Geochemistry. Journal of Contaminant Hydrology, 38, (1 
3), 107156. New York, New York: Elsevier. TIC: 244160. 
156809 Sorey, M.L. and Lewis, R.E. 1976. Convective Heat Flow From Hot Springs in the 
Long Valley Caldera, Mono County, California. Journal of Geophysical Research, 
81, (5), 785791. Washington, D.C.: American Geophysical Union. TIC: 251349. 
156816 Sorey, M.L.; Suemnicht, G.A.; Sturchio, N.C.; and Nordquist, G.A. 1991. New 
Evidence on the Hydrothermal System in Long Valley Caldera, California, from 
Wells, Fluid Sampling, Electrical Geophysics, and Age Determinations of Hot-Spring 
Deposits. Journal of Volcanology and Geothermal Research, 48, 229263. 
Amsterdam, The Netherlands: Elsevier. TIC: 251348. 
156400 Starr, R.C. and Rohe, M.J. 1995. Large-Scale Aquifer Stress Test and Infiltration 
Test: Water Management System Operation and Results. INEL-95/059. Idaho Falls, 
Idaho: Idaho National Engineering Laboratory. TIC: 250953. 
156714 Steefel, C.I. and Lichtner, P.C. 1998. Multicomponent Reactive Transport in 
Discrete Fractures II: Infiltration of Hyperalkaline Groundwater at Maqarin, Jordan, 
a Natural Analogue Site. Journal of Hydrology, 209, (14), 200224. New York, 
New York: Elsevier. TIC: 251162. 
156343 Stefnsson, V. 1997. Geothermal Reinjection Experience. Geothermics, 26, (1), 
99139. New York, New York: Pergamon Press. TIC: 250947. 
156642 Stein, B. and Warrick, S.F. 1979. Granite Mountains Resource Survey, Natural and 
Cultural Values of the Granite Mountains, Eastern Mojave Desert, California. 
Publication No. 1. Santa Cruz, California: University of California, Santa Cruz, 
Environmental Field Program. TIC: 251328. 
156686 Steingrimsson, B.; Bodvarsson, G.S.; Gunnlaugsson, E.; Gislason, G.; and 
Sigurdsson, O. 2000. Modeling Studies of the Nesjavellir Geothermal Field, 
Iceland. Proceedings of the World Geothermal Congress 2000, Kyushu-Tohoku, 
Japan, May 28June 10, 2000. Iglesias, E.; Blackwell, D.; Hunt, T.; Lund, J.; and 
Tamanyu, S.; eds. Pages 28992904. Auckland, New Zealand: International 
Geothermal Association. TIC: 251140. 
154501 Stevens, P.R. 1977. A Review of the Effects of Earthquakes on Underground Mines. 
Open-File Report 77-313. Reston, Virginia: U.S. Geological Survey. TIC: 211779. 
117820 Stockman, H.; Krumhansl, J.; Ho, C.; and McConnell, V. 1994. The Valles Natural 
Analogue Project. NUREG/CR-6221. Washington, D.C.: U.S. Nuclear Regulatory 
Commission. TIC: 246123. 

100419 Stout, R.B. and Leider, H.R., eds. 1997. Waste Form Characteristics Report 
Revision 1. UCRL-ID-108314. Version 1.2. Livermore, California: Lawrence 
Livermore National Laboratory. ACC: MOL.19980512.0133. 
156614 Strobel, C.J. 1993. Bulalo Field, Philippines: Reservoir Modeling for Prediction of 
Limits to Sustainable Generation. Proceedings, Eighteenth Workshop, Geothermal 
Reservoir Engineering, January 2628, 1993. Ramey, H.J., Jr.; Horne, R.N.; Kruger, 
P.; Miller, F.G.; Brigham, W.E.; and Cook, J.W., eds. Workshop Report SGP-TR- 
145. Pages 510. Stanford, California: Stanford University. TIC: 246821. 
151957 Stuckless, J.S. 2000. Archaeological Analogues for Assessing the Long-Term 
Performance of a Mined Geologic Repository for High-Level Radioactive Waste. 
Open-File Report 00-181. Denver, Colorado: U.S. Geological Survey. ACC: 
MOL.20000822.0366. 
154525 Sturchio, N.C.; Binz, C.M.; and Lewis, C.H., III 1987. Thorium-Uranium 
Disequilibrium in a Geothermal Discharge Zone at Yellowstone. Geochimica et 
Cosmochimica Acta, 51, (7), 20252034. New York, New York: Pergamon Press. 
TIC: 249702. 
154529 Sturchio, N.C.; Bohlke, J.K.; and Binz, C.M. 1989. Radium-Thorium 
Disequilibrium and Zeolite-Water Ion Exchange in a Yellowstone Hydrothermal 
Environment. Geochimica et Cosmochimica Acta, 53, 10251034. New York, New 
York: Pergamon Press. TIC: 249703. 
154524 Sturchio, N.C.; Keith, T.E.C.; and Muehlenbachs, K. 1990. Oxygen and Carbon 
Isotope Ratios of Hydrothermal Minerals from Yellowstone Drill Cores. Journal of 
Volcanology and Geothermal Research, 40, 2337. Amsterdam, The Netherlands: 
Elsevier. TIC: 249710. 
156253 Sturchio, N.C.; Muehlenbachs, K.; and Seitz, M.G. 1986. Element Redistribution 
During Hydrothermal Alteration of Rhyolite in an Active Geothermal System: 
Yellowstone Drill Cores Y-7 and Y-8. Geochimica et Cosmochimica Acta, 50, (8), 
16191631. New York, New York: Pergamon Journals. TIC: 250863. 
156923 Tagami, K. and Uchida, S. 1999. Chemical Transformation of Technetium in Soil 
During the Change of Soil Water Conditions. Chemosphere, 38, (5), 963971. New 
York, New York: Elsevier. TIC: 251292. 
156920 Tarapon, A.G. 2001. Reconstruction of the Accident at Chernobyl NPP Using 
Models of Heat and Mass Transfer. Electronic Modeling, 23, (3), 89104. Kiev, 
Ukraine: National Academy of Science of Ukraine. TIC: 251290. 
157439 Thomassin, J.H. and Rassineux, F. 1992. Ancient Analogues of Cement-Based 
Materials: Stability of Calcium Silicate Hydrates. Applied Geochemistry, 
Supplemental Issue No. 1, 137142. New York, New York: Pergamon Press. TIC: 
251663. 

157429 Toprak, V.; Keller, J.; and Schumacher, R. 1994. Volcano-tectonic Features of the 
Cappadocian Volcanic Province. 1994 International Volcanology Congress of the 
International Association of Volcanology and Chemistry of the Earths Interior. 58 
pages. Amsterdam, The Netherlands: Elsevier. On Order Library Tracking Number- 
251890. 
101024 Triay, I.R.; Furlano, A.C.; Weaver, S.C.; Chipera, S.J.; and Bish, D.L. 1996. 
Comparison of Neptunium Sorption Results Using Batch and Column Techniques. 
LA-12958-MS. Los Alamos, New Mexico: Los Alamos National Laboratory. ACC: 
MOL.19980924.0049. 
100422 Triay, I.R.; Meijer, A.; Conca, J.L.; Kung, K.S.; Rundberg, R.S.; Strietelmeier, B.A.; 
and Tait, C.D. 1997. Summary and Synthesis Report on Radionuclide Retardation 
for the Yucca Mountain Site Characterization Project. Eckhardt, R.C., ed. LA- 
13262-MS. Los Alamos, New Mexico: Los Alamos National Laboratory. ACC: 
MOL.19971210.0177. 
156350 Truesdell, A.H.; DAmore, F.; and Nieva, D. 1984. The Effects of Localized 
Aquifer Boiling on Fluid Production at Cerro Prieto. Geothermal Resources Council 
Transactions, 8, 223229. Davis, California: Geothermal Resources Council. TIC: 
250948. 
137577 Tsang, Y.W. and Birkholzer, J.T. 1999. Predictions and Observations of the 
Thermal-Hydrological Conditions in the Single Heater Test. Journal of 
Contaminant Hydrology, 38, (13), 385425. New York, New York: Elsevier. TIC: 
244160. 
156925 Uchida, S.; Tagami, K.; Rhm, W.; and Wirth, E. 1999. Determination of 99Tc 
Deposited on the Ground Within the 30-km Zone around the Chernobyl Reactor and 
Estimation of 99Tc Released into Atmosphere by the Accident. Chemosphere, 39, 
(15), 27572766. New York, New York: Elsevier. TIC: 251293. 
156945 Uchida, S.; Tagami, K.; Wirth, E.; and Rhm, W. 1999. Concentration Levels of 
Technetium-99 in Forest Soils Collected Within the 30-km Zone Around the 
Chernobyl Reactor. Environmental Pollution, 105, 7577. Barking, Essex, 
England: Elsevier. TIC: 251333. 
157515 Undara Experience. 2001. Undara Experience: Australia's Accessible Outback. 
Queensland, Australia: Undara Experience. Accessed January 30, 2002. 
http://www.undara-experience.com.au Copyright Requested Library Tracking 
Number-251752. 
156398 Unger, A.J.A.; Faybishenko, B.; Bodvarsson, G.S.; and Simmons, A.M. 2002. A 
Three-Dimensional Model for Simulating Ponded Infiltration Tests in the Variably 
Saturated Fractured Basalt at the Box Canyon Site, Idaho. LBNL-44633. Berkeley, 
California: Lawrence Berkeley National Laboratory. ACC: MOL.20020213.0195. 

157415 USGS. 2000. Review of the transport of selected radionuclides in the Interim Risk 
Assessment for the Radioactive Waste Management Complex, Waste Area Group 7 
Operable Unit 7-13/14. Administrative Report. Volumes I and II. Idaho Falls, 
Idaho: Idaho National Engineering and Environmental Laboratory. ACC: 
MOL.20040512.0313; MOL.20040512.0315. 
100354 USGS (U.S. Geological Survey). 1998. Probabilistic Seismic Hazard Analyses for 
Fault Displacement and Vibratory Ground Motion at Yucca Mountain, Nevada. 
Milestone SP32IM3, June 15, 1998. Three volumes. Oakland, California: U.S. 
Geological Survey. ACC: MOL.19980619.0640. 
157517 USGS. 2000. Lava Tube. Photo Glossary of Volcano Terms. Menlo Park, 
California: U.S. Geological Survey. Accessed January 30, 2002. TIC: 251751. 
http://volcanoes.usgs.gov/Products/Pglossary/LavaTube.html 
119132 Valentine, G.A.; WoldeGabriel, G.; Rosenberg, N.D.; Carter Krogh, K.E.; Crowe, 
B.M.; Stauffer, P.; Auer, L.H.; Gable, C.W.; Goff, F.; Warren, R.; and Perry, F.V. 
1998. Physical Processes of Magmatism and Effects on the Potential Repository: 
Synthesis of Technical Work Through Fiscal Year 1995. Chapter 5 of Volcanism 
Studies: Final Report for the Yucca Mountain Project. Perry, F.V.; Crowe, B.M.; 
Valentine, G.A.; and Bowker, L.M., eds. LA-13478. Los Alamos, New Mexico: Los 
Alamos National Laboratory. TIC: 247225. 
100610 van Genuchten, M.T. 1980. A Closed-Form Equation for Predicting the Hydraulic 
Conductivity of Unsaturated Soils. Soil Science Society of America Journal, 44, (5), 
892898. Madison, Wisconsin: Soil Science Society of America. TIC: 217327. 
155042 Vandergraaf, T.T.; Drew, D.J.; Ticknor, K.V.; and Seddon, W.A. 2001. 
Radionuclide Migration in Tuff Under Unsaturated Conditions. Back to the 
FutureManaging the Back End of the Nuclear Fuel Cycle to Create a More Secure 
Energy Future, Proceedings of the 9th International High-Level Radioactive Waste 
Management Conference (IHLRWM), Las Vegas, Nevada, April 29May 3, 2001. La 
Grange Park, Illinois: American Nuclear Society. TIC: 247873. 
105946 Vaniman, D.T.; Bish, D.L.; Chipera, S.J.; Carlos, B.A.; and Guthrie, G.D., Jr. 1996. 
Chemistry and Mineralogy of the Transport Environment at Yucca Mountain. 
Volume I of Summary and Synthesis Report on Mineralogy and Petrology Studies for 
the Yucca Mountain Site Characterization Project. Milestone 3665. Los Alamos, 
New Mexico: Los Alamos National Laboratory. ACC: MOL.19961230.0037. 
157427 Vaniman, D.T.; Chipera, S.J.; Bish, D.L.; Carey, J.W.; and Levy, S.S. 2001. 
Quantification of Unsaturated-Zone Alteration and Cation Exchange in Zeolitized 
Tuffs at Yucca Mountain, Nevada, USA. Geochimica et Cosmochimica Acta, 65, 
(20), 34093433. New York, New York: Elsevier. TIC: 251574. 
157416 Vigil, M.J. 1988. Estimate of Water in Pits During Flooding Events. Engineering 
Design File BWP-12. Idaho Falls, Idaho: EG&G Idaho. TIC: 251846. 

108261 Vilks, P.; Cramer, J.J.; Bachinski, D.B.; Doern, D.C.; and Miller, H.G. 1993. 
Studies of Colloids and Suspended Particles, Cigar Lake Uranium Deposit, 
Saskatchewan, Canada. Applied Geochemistry, 8, (6), 605616. London, England: 
Pergamon Press. TIC: 237449. 
156656 Villadolid, F.L. 1991. The Applications of Natural Tracers in Geothermal 
Development: The Bulalo, Philippines Experience. Proceedings of the 13th New 
Zealand Geothermal Workshop, 1991. Freeston, D.H.; Browne, P.R.L.; and Scott, 
G.L., eds. Pages 6974. Auckland, New Zealand: Geothermal Institute, The 
University of Auckland. TIC: 251257. 
145806 Villar, E.; Bonet, A.; Diaz-Caneja, B.; Fernandez, P.L.; Gutierrez, I.; Quindos, L.S.; 
Solana, J.R.; and Soto, J. 1985. Natural Evolution of Percolation Water in Altamira 
Cave. Cave Science, 12, (1), 2124. Bridgwater, United Kingdom: British Cave 
Research Association. TIC: 247713. 
156921 Voitsekhovitch, O.; Prister, B.; Nasvit, O.; Los, I.; and Berkovski, V. 1996. Present 
Concept on Current Water Protection and Remediation Activities for the Areas 
Contaminated by the 1986 Chernobyl Accident. Health Physics, 71, (1), 1928. 
New York, New York: Pergamon. TIC: 251291. 
127454 Walton, J.C. 1994. Influence of Evaporation on Waste Package Environment and 
Radionuclide Release from a Tuff Repository. Water Resources Research, 30, (12), 
34793487. Washington, D.C.: American Geophysical Union. TIC: 246921. 
151821 Wang, J-M. 1985. The Distribution of Earthquake Damage to Underground 
Facilities During the 1976 Tang-Shan Earthquake. Earthquake Spectra, 1, (4), 741 
757. Berkeley, California: Earthquake Engineering Research Institute. TIC: 226272. 
154297 Weeks, K.R. 1998. Valley of the Kings. National Geographic, 194, (3), 533. 
Washington, D.C.: National Geographic Society. TIC: 249629. 
156644 Weres, O. and Apps, J.A. 1982. Prediction of Chemical Problems in the 
Reinjection of Geothermal Brines. Recent Trends in Hydrogeology. Narasimhan, 
T.N., ed. Special Paper 189. 407426. Boulder, Colorado: Geological Society of 
America. TIC: 251079. 
154773 Whelan, J.F.; Roedder, E.; and Paces, J.B. 2001. Evidence for an Unsaturated-Zone 
Origin of Secondary Minerals in Yucca Mountain, Nevada. Back to the Future 
Managing the Back End of the Nuclear Fuel Cycle to Create a More Secure Energy 
Future, Proceedings of the 9th International High-Level Radioactive Waste 
Management Conference (IHLRWM), Las Vegas, Nevada, April 29May 3, 2001. La 
Grange Park, Illinois: American Nuclear Society. TIC: 247873. 
156452 Whitbeck, M. and Glassley, W.E. 1998. Reaction Path Model for Water Chemistry 
and Mineral Evolution in the Altered Zone. Chapter 5.3 of Near-Field/Altered-Zone 
Models Report. UCRL-ID-129179 DR. Livermore, California: Lawrence Livermore 
National Laboratory. ACC: MOL.19980504.0577. 

156814 White, A.F. 1986. Chemical and Isotopic Characteristics of Fluids within the Baca 
Geothermal Reservoir, Valles Caldera, New Mexico. Journal of Geophysical 
Research, 91, (B2), 18551866. Washington, D.C.: American Geophysical Research 
Union. TIC: 251350. 
154530 White, D.E.; Fournier, R.O.; Muffler, L.J.P.; and Truesdell, A.H. 1975. Physical 
Results of Research Drilling in Thermal Areas of Yellowstone National Park, 
Wyoming. Geological Survey Professional Paper 892. Washington, D.C.: U.S. 
Government Printing Office. TIC: 235251. 
156340 White, S.P.; Kissling, W.M.; and McGuinness, M.J. 1997. Models of the Kawareu 
Geothermal Reservoir. Geothermal Resources Council Transactions, 21, 3339. 
Davis, California: Geothermal Resources Council. TIC: 250949. 
157442 Wieland, E. and Spieler, P. 2001. Colloids in the Mortar Backfill of a Cementitious 
Repository for Radioactive Waste. Waste Management, 21, (6), 511523. New 
York, New York: Elsevier. TIC: 251666. 
156613 Williamson, K.H. 1992. Development of a Reservoir Model for the Geysers 
Geothermal Field. Monograph on the Geysers Geothermal Field. Stone, C., ed. 
Special Report No. 17. Pages 179187. Davis, California: Geothermal Resources 
Council. TIC: 251066. 
156254 Winograd, I.J. 1971. Hydrogeology of Ash Flow Tuff: A Preliminary Statement. 
Water Resources Research, 7, (4), 9941006. Washington, D.C.: American 
Geophysical Union. TIC: 217736. 
127015 Winograd, I.J. 1986. Archaeology and Public Perception of a Transscientific 
ProblemDisposal of Toxic Wastes in the Unsaturated Zone. Circular 990. Denver, 
Colorado: U.S. Geological Survey. TIC: 237946. 
110071 WoldeGabriel, G.; Keating, G.N.; and Valentine, G.A. 1999. Effects of Shallow 
Basaltic Intrusion into Pyroclastic Deposits, Grants Ridge, New Mexico, USA. 
Journal of Volcanology and Geothermal Research, 92, (3), 389411. New York, 
New York: Elsevier. TIC: 246037. 
156741 Wolery, T.J. 1979. Calculation of Chemical Equilibrium between Aqueous Solution 
and Minerals: The EQ3/6 Software Package. UCRL-52658. Livermore, California: 
Lawrence Livermore Laboratory. ACC: HQS.19880517.2586. 
157417 Wolfram, S. 1991. Mathematica, A System for Doing Mathematics by Computer. 
2nd Edition. Redwood City, California: Addison-Wesley. TIC: 251766. 
157467 Wollenberg, H.A.; Flexser, S.; and Smith, A.R. 1995. Mobility and Depositional 
Controls of Radioelements in Hydrothermal Systems at the Long Valley and Valles 
Calderas. Journal of Volcanology and Geothermal Research, 67, (13), 171186. 
Amsterdam, The Netherlands: Elsevier. TIC: 251861 

168457 Wong, V.; Anthony, E.; and Goodell, P. 1996. Nopal I Uranium Deposit: A Study 
of Radionuclide Migration. High-Level Radioactive Waste Management, 
Proceedings of the Seventh Annual International Conference, Las Vegas, Nevada, 
April 29May 3, 1996. Pages 4345. La Grange Park, Illinois: American Nuclear 
Society. TIC: 226469. 
102047 Wronkiewicz, D.J.; Bates, J.K.; Wolf, S.F.; and Buck, E.C. 1996. Ten-Year Results 
from Unsaturated Drip Tests with UO2 at 90C: Implications for the Corrosion of 
Spent Nuclear Fuel. Journal of Nuclear Materials, 238, (1), 7895. Amsterdam, 
The Netherlands: North-Holland. TIC: 243361. 
117161 Wu, Y.S.; Haukwa, C.; and Bodvarsson, G.S. 1999. A Site-Scale Model for Fluid 
and Heat Flow in the Unsaturated Zone of Yucca Mountain, Nevada. Journal of 
Contaminant Hydrology, 38, (13), 185215. New York, New York: Elsevier. TIC: 
244160. 
156399 Wu, Y.S.; Liu, H.H.; Bodvarsson, G.S.; and Zellmer, K.E. 2001. A Triple- 
Continuum Approach for Modeling Flow and Transport Processes in Fractured 
Rock. LBNL-48875. Berkeley, California: Lawrence Berkeley National Laboratory. 
TIC: 251297. 
156453 Wu, Y.S.; Ritcey, A.C.; Ahlers, C.F.; Mishra, A.K.; Hinds, J.J.; and Bodvarsson, G.S. 
1997. Providing Base-Case Flow Fields for TSPA-VA: Evaluation of Uncertainty of 
Present-Day Infiltration Rates Using DKM/Base-Case and DKM/Weeps Parameter 
Sets. Milestone SLX01LB2. Berkeley, California: Lawrence Berkeley National 
Laboratory. ACC: MOL.19980501.0475. 
117167 Wu, Y.S.; Haukwa, C.; and Bodvarsson, G.S. 1999. A Site-Scale Model for Fluid 
and Heat Flow in the Unsaturated Zone of Yucca Mountain, Nevada. Journal of 
Contaminant Hydrology, 38, (13), 185215. New York, New York: Elsevier. TIC: 
244160. 
156280 Xu, T. and Pruess, K. 2001. Modeling Multiphase Non-Isothermal Fluid Flow and 
Reactive Geochemical Transport in Variably Saturated Fractured Rocks: 1. 
Methodology. American Journal of Science, 301, 1633. New Haven, Connecticut: 
Yale University, Kline Geology Laboratory. TIC: 251482. 
100194 Yang, I.C.; Rattray, G.W.; and Yu, P. 1996. Interpretation of Chemical and Isotopic 
Data from Boreholes in the Unsaturated Zone at Yucca Mountain, Nevada. Water- 
Resources Investigations Report 96-4058. Denver, Colorado: U.S. Geological 
Survey. ACC: MOL.19980528.0216. 
156443 Zavarin, M. and Bruton, C.J. 2000. A Non-Electrostatic Surface Complexation 
Approach to Modeling Radionuclide Migration at the Nevada Test Site: 
Aluminosilicates. UCRL-1D-141840 DR. Livermore, California: Lawrence 
Livermore National Laboratory. ACC: MOL.20040512.0307. 

156444 Zavarin, M. and Bruton, C.J. 2002. A Non-electrostatic Surface Complexation 
Approach to Modeling Radionuclide Migration at the Nevada Test Site: Iron Oxides 
and Calcite. UCRL-1D-141841 DR. Livermore, California: Lawrence Livermore 
National Laboratory. ACC: MOL.20040512.0305. 
157501 Zetterstrm, L. 2000. Oklo, A Review and Critical Evaluation of Literature. SKB 
TR 00-17. Stockholm, Sweden: Svensk Krnbrnslefrsrjning A.B. TIC: 249383. 
156951 Zhdanaova, N.; Redchitz, T.; Vasilevskaya, A.I.; Vember, V.; Fomina, M.; 
Zheltonozhsky, V.A.; Bondarkov, M.D.; Lashko, T.N.; Ukhin, M.A.; Olsson, St.; 
Mck, K.; Strebl, F.; and Gerzabek, M.H. 2000. Interaction between Biota 
Micromycetes and Hot Particles after the Chernobyl NPP Accident and Atomic 
Explosions and Investigation of Their Influence in Rehabilitating Contaminated 
Areas, Final Report. INTAS-UKRAINE 95-0171. Seibersdorf, Austria: Austrian 
Research Centers. TIC: 251553. 
156630 Zheltonozhsky, V.; Mck, K.; and Bondarkov, M. 2001. Classification of Hot 
Particles from the Chernobyl Accident and Nuclear Weapons Detonations by Non- 
Destructive Methods. Journal of Environmental Radioactivity, 57, (2), 151166. 
New York, New York: Elsevier. TIC: 251077. 
138273 Zimmerman, R.M.; Schuch, R.L.; Mason, D.S.; Wilson, M.L.; Hall, M.E.; Board, 
M.P.; Bellman, R.P.; and Blanford, M.L. 1986. Final Report: G-Tunnel Heated 
Block Experiment. SAND84-2620. Albuquerque, New Mexico: Sandia National 
Laboratories. ACC: MOL.19961217.0085. 
163341 Zyvoloski, G.; Kwicklis, E.; Eddebbarh, A.A.; Arnold, B.; Faunt, C.; and Robinson, 
B.A. 2003. The Site-Scale Saturated Zone Flow Model for Yucca Mountain: 
Calibration of Different Conceptual Models and their Impact on Flow Paths. 
Journal of Contaminant Hydrology, 62-63, 731-750. [New York, New York]: 
Elsevier. TIC: 254340. 
100615 Zyvoloski, G.A.; Robinson, B.A.; Dash, Z.V.; and Trease, L.L. 1997. Users 
Manual for the FEHM ApplicationA Finite-Element Heat- and Mass-Transfer Code. 
LA-13306-M. Los Alamos, New Mexico: Los Alamos National Laboratory. TIC: 
235999. 
16.2 CODES, STANDARDS, REGULATIONS, AND PROCEDURES 
156671 66 FR 55732. Disposal of High-Level Radioactive Wastes in a Proposed Geologic 
Repository at Yucca Mountain, NV, Final Rule. 10 CFR Parts 2, 19, 20, 21, 30, 40, 
51, 60, 61, 63, 70, 72, 73, and 75. Readily available. 
AP-2.14Q, REV 2, ICN 0. Review of Technical Products and Data. Washington, 
D.C.: U.S. Department of Energy, Office of Civilian Radioactive Waste 
Management. ACC: MOL.20010801.0316. 

AP-3.11Q, Rev. 4, ICN 1. Technical Reports. Washington, D.C.: U.S. Department 
of Energy, Office of Civilian Radioactive Waste Management. ACC: 
DOC.20040217.0001. 
AP-SIII.1Q, Rev. 2, ICN 0. Scientific Notebooks. Washington, D.C.: U.S. 
Department of Energy, Office of Civilian Radioactive Waste Management. ACC: 
MOL.20021202.0026. 
AP-SIII.3Q, Rev.2, ICN 1. Submittal and Incorporation of Data to the Technical 
Data Management System. Washington, D.C.: U.S. Department of Energy, Office of 
Civilian Radioactive Waste Management. ACC: DOC.20040226.0001. 
LP-SI.11Q-BSC, Rev. 0. Software Management. Washington, D.C.: U.S. 
Department of Energy, Office of Civilian Radioactive Waste Management. ACC: 
DOC.20040225.0007. 
16.3 SOFTWARE 
Not Applicable 
16.4 SOURCE DATA 
145412 GS980908312322.008. Field, Chemical, and Isotopic Data from Precipitation 
Sample Collected Behind Service Station in Area 25 and Ground Water Samples 
Collected at Boreholes UE-25 C #2, UE-25 C #3, USW UZ-14, UE-25 WT #3, UE- 
25 WT #17, and USW WT-24, 10/06/97 to 07/01/98. Submittal date: 09/15/1998. 
169288 LA0403MM835131.001. Natural Analog Studies at Pea Blanca, Mexico. Submittal 
date: 03/10/2004. 
157569 LB0201YSANALOG.001. Permeability and Porosity Measurements of Core 
Samples from Core Samples at Yellowstone National Park. Submittal date: 
01/25/2002. 
157610 LB0202PBANALOG.001. Stable Isotope Analyses of Pea Blanca Waters. 
Submittal date: 02/12/2002. 
168014 LB0402PBCORELG.001. Core Description for PB-1. Submittal date: 02/27/2004. 
168016 LB0402PBDRLLGS.001. Drilling Log Descriptions for PB-1, PB-2, and PB-3. 
Submittal date: 02/27/2004. 
168017 LB0402PBGPHLGS.001. Geophysical Log Data for PB-1, PB-2, PB-3, and PB-4. 
Submittal date: 02/27/2004. 
168018 LB0402PBMNRLGY.001. Petrographic Descriptions of Rock Samples from PB-1, 
PB-2, and PB-3. Submittal date: 02/27/2004. 

168268 LB0403PBFLDATA.001. Pea Blanca Field Data. Submittal date: 03/11/2004. 
168269 LB0403 PBTVXTRC.001. Pea Blanca Televiewer Log Extractions. Submittal date: 
03/11/2004. 
16.5 OUTPUT DATA 
Not Applicable 

ATTACHMENT I. 
GEOPHYSICAL LOGGING 

ATTACHMENT I. GEOPHYSICAL LOGGING 
As part of the geologic and geophysical characterization of the Pea Blanca wells, geophysical 
logs were run in the wells PB-1, PB-2, PB-3, and PB-4. Detailed descriptions and data from 
these logging runs are in Garay Jimenez (2003 [168019]), Federal Commission of Electricity 
(2003 [168021]), and DTN: LB0402PBGPHLGS.001 [168017]. Interpretive summaries of the 
geophysical logs are presented below. 
I.1. PB-1 LOGGING RESULTS 
Natural GammaThe range of natural gamma values in PB-1 (Figure I-1) varies from 160 to 
144,490 counts per second (cps). The highest values (> 50,000 cps) are encountered in the upper 
15 m of the borehole and correspond to a zone of intense alteration. Below this zone, there is a 
general trend towards lower gamma values with depth, with some occasional hot spots. Near the 
water table (located at 222.6 msee Table 10.4-4), there is a narrow zone (216.6225.1 m) with 
distinctly higher gamma values (all above 2,500 cps, with a maximum value of 7,927 cps). 
Below this zone, gamma values drop rapidly, and at depths greater than 227.1 m, all gamma 
values are below 400 cps. 
Radiation readings made on core samples obtained from the PB-1 well yielded much lower 
readings than the natural gamma log measurements. The core sample measurements were 
= 1,200 cps, with most values < 200 cps (DTN: LB0402PBDRLLGS.001 [168016]; DTN; 
LB0402PBCORELG.001 [168014]). Measurements on the core samples were made using handheld 
radiometers at the time of core retrieval at the rig site and were repeated when the core was 
described back at the Autonomous University of Chihuahua (AUCH) laboratory. The values 
obtained at the rig site are systematically higher than those measured back in Chihuahua and may 
reflect a higher background value resulting from the presence of the Nopal I uranium deposit. 
Part of the difference between the higher borehole values and the core measurements may be a 
result of differences in tool sensitivity and the larger amount of rock mass sampled by the 
downhole tool. However, although these differences would account for differences in the 
magnitude of the gamma values, they would not explain differences in the locations of hot spots. 
The most striking difference between the natural gamma log and the core measurements was the 
absence of the extremely high values detected by the geophysical log within the upper 15 m of 
PB-1. The highest value obtained from the core samples within this depth interval is 280 cps 
from the field measurements and 170 cps from the laboratory measurements; these values are 
dwarfed by the natural gamma log values of 7,370144,490 cps for the same interval. This 
discrepancy is most likely due to the location of PB-1 just outside the boundary of the Nopal I 
uranium ore body. The core samples do not appear to have significant uranium mineralization, 
thus supporting the relatively low core radiation levels. The proximity of the upper portion of 
the PB-1 borehole to the Nopal I uranium ore body is most likely the cause for the extremely 
high gamma log values. 
The zone of elevated natural gamma values observed near the top of the water table was also 
encountered in the core measurements, where hot spots with values ranging up to 420 cps (field 
measurements) and 250 cps (laboratory measurements) were obtained. The highest PB-1 core 
values for both field and laboratory measurements were measured within a section of highly 

altered and fractured conglomerate at a depth of 190 m, where values of 1,200 cps (field) and 
400 cps (lab) were obtained. The corresponding natural gamma log value for this depth was 
1,590 cps, which is not significantly different from the surrounding borehole values. It appears 
that this core hot spot is not large enough to be resolved by the downhole logging tool. 
NeutronThere is a fairly restricted range of neutron log values throughout the unsaturated 
zone of PB-1 (Figure I-1), with most values ranging between 2,0003,000 American Petroleum 
Institute (API) units. The sudden drop in the neutron log at 222.7 m, where values drop from 
above 2,000 down to around 100 API units, is associated with the location of the water table 
(Table 10.4-4). There is a small shift in values occurring at 246.2 m, where values increase from 
around 100 API units (for the region above this depth and within the saturated zone) to values 
typically between 250600 API units. This depth is very close to the contact between the Pozos 
conglomerate and the Cretaceous limestone (244.4 m) observed in the PB-1 core. 
DensityShort-spacing (source-to-receiver distance of 6 inches) gamma-gamma density logs 
provide information about well construction and conditions close to the annulus of the well, 
whereas long-spacing (source-to-receiver distance of 12 inches) logs provide information on 
lithologic units, bulk density, porosity, and moisture content. The values of two different 
gamma-gamma density logs, short spacing (SS) and long spacing (LS), were reported for PB-1 
by Comisin Federal de Electricidad (CFE) (Figure I-1). The lowest density values were 
recorded in the upper 15 m of the borehole (within the highly altered Nopal tuff), where the SS 
and LS density values typically range from 0.3 to 1.3 and 0.2 to 0.9 g/cc, respectively. Density 
values for both logs between the depths of 15 and 145 m increase gradually with depth and 
exhibit little variability, with values typically ranging between 1.5 and 2.2 g/cc. Density values 
for both logs exhibit greater variability between 145 m and the top of the water table (222.6 m), 
as would be expected for this interval within the lithologically diverse Pozos conglomerate. At 
depths below the water table, the LS log yields values that are higher by about 1 g/cc than those 
obtained from the SS log. 
ResistivityThree different resistivity logs were run in the zone below the water table. The log 
responses of the normal short (16N) and lateral resistivity logs are very similar, with most values 
in the SZ ranging from 50 to 250 ohm-m. Higher values (up to 790 ohm-m) were recorded by 
the normal long (64N) resistivity log. The lowest resistivity values for all three logs (48.5 and 
41.0 ohm-m for the 16N log and lateral log, respectively, at a depth of 245.5 m and 56.5 ohm-m 
for the 64N log at a depth of 244.2 m) were recorded close to the contact between the Pozos 
conglomerate and the underlying Cretaceous limestone (244.4 m). The presence of clay 
observed in the PB-1 core at this contact might account for the low resistivity values. 
TeleviewerThe televiewer log provides the opportunity to identify fractures and other features 
within the uncased borehole. Casing is present in the upper 2.1 m of the PB-1 borehole. 
Fractures and cavities within the borehole were identified in over 30 intervals within PB-1 
(DTN: LB0403PBTVXTRC.001 [168269]). Examples of some of the fractures are shown in 
Figures I-2 and I-3. Most of the fractures are located within the Coloradas tuff, whereas most of 
the cavities are located within the Pozos conglomerate. The appearance of a zone with abundant 
clasts within the PB-1 televiewer log at a depth of around 136.6 m is interpreted to represent the 
contact between the tuff and conglomerate units and is in good agreement with the contact 
identified in the PB-1 core at 136.4 m. The static water level (Table 10.4-4) was encountered at 

a depth of 218.5 m, which is 4.2 m shallower than the depth indicated by the neutron log (222.7 
m). The difference between these two measurements is most likely indicative of the relative 
error in the depth measurement between these two logging runs. 
I.2. PB-2 LOGGING RESULTS 
Natural GammaNatural gamma values in PB-2 vary from 125 to 10,571 cps, with the bulk of 
the logged section having values less than 500 cps (Figure I-4). There are a number of zones 
with elevated values (> 1,000 cps) within PB-2, mostly occurring within the Pozos 
conglomerate. Unlike the PB-1 well, the section of PB-2 through the Nopal rhyolite had 
relatively low gamma values (< 700 cps). The lack of elevated gamma values in the upper 
portion of the PB-2 well is consistent with the observation that there is an abrupt drop-off in 
radioactivity outside of the area of visible U mineralization, as the wellhead for PB-2 is located 
42 m away from PB-1 and is outside of the zone of elevated surface gamma measurements 
reported in Figure 5 of Pearcy et al. (1995 [110223]). The zone with the highest recorded value 
in PB-2 (occurring between 224.6227.3 m) is located just above the top of the water table 
(228.6 m), similar to the feature found in the PB-1 well. A zone with high gamma values (> 
2,000 cps) was also detected within the SZ (between 230.4 m and lowest logged depth of 234.9 
m). 
NeutronThere is a fairly restricted range of neutron log values throughout the UZ of PB-2 
with most values ranging between 2,0003,000 API units (Figure I-4). The sudden drop in the 
neutron log at 230.3 m, where values drop from above 2,000 down to below 200 API units, is 
associated with the location of the water table (Table 10.4-4). The geophysical logs were only 
run to a depth of 235.7 m (prior to deepening the well to its final depth of 253.7 m), and thus, the 
contact between the Pozos conglomerate and the Cretaceous limestone, estimated to be at around 
a depth of ~242.9 m based on a color change in the cuttings (DTN: LB0402PBCORELG.001 
[168014]), was not logged in PB-2. 
DensityThe values of two different gamma-gamma density logs, SS and LS, were reported for 
PB-2 by CFE (Figure I-4). The LS density values tend to be about 0.30.4 g/cc higher than the 
corresponding SS values. Over the upper 143-m section of PB-2 (within the rhyolitic tuff units), 
density values are fairly uniform, with a gradual increase in values (from 2.0 to 2.5 in LS 
density) observed with increasing depth. Below 143 m, density values for both logs exhibit 
greater variability, as would be expected for this interval within the lithologically diverse Pozos 
conglomerate, and thus, this transition was interpreted to represent the contact between the 
Coloradas tuffs and the Pozos conglomerate. 
ResistivityDue to the small depth interval (~ 5 m) of the SZ at the time of logging PB-2, there 
is a paucity of resistivity data for this well. According to the CFE geophysical log report (Garay 
Jimnez et al. 2003 [168019]), these values vary between 170200 ohm-m for the normal short, 
normal long, and lateral resistivity logs. 
I.3. PB-3 LOGGING RESULTS 
The completion of the upper portion of PB-3 differs slightly from wells PB-1 and PB-2 because a 
void was encountered between the depths of 25.8 and 27.0 m, which resulted in large losses in 

circulation (Ariceaga-Martinez 2003 [168020]). To address this problem, a steel liner with a 
nominal diameter of 8 in. was emplaced (and cemented) down to a depth of 26.88 m. The 
presence of the steel liner and cement in the upper 26.88 m of the borehole affects the results of 
the neutron and density logs, resulting in anomalously low neutron values and high density 
values. The natural gamma values for this interval also appear to have been attenuated. 
Natural GammaNatural gamma values in PB-3 vary from 308 to 32,257 cps (Figure I-5). 
Gamma values are fairly low (typically 1,000 to 2,000 cps) in the upper 205 m of PB-3, with a 
trend towards gradually increasing values with depth. Within this upper portion of the borehole, 
there are two intervals (beginning at depths of 90 and 131 m) where gamma values increase more 
sharply, followed by a larger range in values. The increase at 131 m is interpreted to represent 
the contact between the Coloradas tuff and the Pozos conglomerate. Between 205 and 228 m, 
gamma values are all above 2,000 cps, with values greater than 7,000 cps restricted to a narrow 
interval between 219 and 228 m depth, located just below the measured water level in the well 
(214.1 m; see Table 10.4-4). This interval corresponds to the only zone in which cuttings 
samples from PB-3 with elevated gamma values were encountered (DTN: 
LB0402PBDRLLGS.001 [168017]; DTN: LB0402PBCORELG.001 [168014]). As noted for 
PB-1, the handheld radiation measurements on the recovered rock samples are substantially 
lower than those obtained from the borehole during the downhole survey. Below 228 m depth, 
borehole gamma values are generally lower, with values ranging between 900 and 2,600 cps. 
NeutronAs noted at the outset, the neutron log values for the upper 26.9 m of PB-3 (1,092 
1,710 API units) appear to be influenced by the presence of the cement and steel casing in this 
interval, as these values are generally lower than the rest of the UZ (Figure I-5). Below this 
depth, there is a fairly restricted range of neutron log values throughout the UZ of PB-3, with 
most values ranging between 2,0003,000 API units. The sudden drop in the neutron log at 
214.9 m, where values fall off from above 2,000 down to around 50400 API units, is associated 
with the location of the water table (Table 10.4-4). 
DensityThe values of two different gamma-gamma density logs, SS and LS, were reported for 
PB-3 by CFE (Figure I-5). Over most of the interval surveyed, there is fairly good agreement 
between the SS and LS log values. Below the top of the static water level, however, the density 
values for SS and LS deviate, with LS values at times more than 1 g/cc higher than the 
corresponding SS measurements. As mentioned earlier, the density log values measured in the 
cased upper portion of the borehole appear to be too high. Between 30 and 100 m depth, 
measured densities are fairly uniform, with most SS and LS values ranging between 1.8 and 2.4 
g/cc (with an average of 2.15 g/cc). This is followed by an interval (100117 m) with some 
variability, below which there is another zone (117131 m) with uniform density values, which 
correlates with a zone of low, uniform gamma counts. Below the 117-131-m zone, density 
values for both density logs exhibit greater variability; this change was interpreted to represent 
the contact between the Coloradas tuff and the Pozos conglomerate. Variability in density at 
these depths was also observed in the PB-1 and PB-2 density logs. 
ResistivityThree different resistivity logs were run in the zone below the water table. The log 
responses of the normal short (16N) and lateral resistivity logs are similar, with most values 
around 100 ohm-m. These two logs identify two low-resistivity (5070 ohm-m) zones; one 
occurs at a depth of 226 m, whereas the other is located at 238242 m. The normal long (64N) 

resistivity log has one high resistivity feature, with values of around 150 ohm-m just below 
(215216 m) the measured water table; this log transitions to fairly low and uniform values 
(typically 5580 ohm-m) below a depth of 220 m. 
TeleviewerThe televiewer log provides the opportunity to identify fractures and other features 
within the uncased borehole. Casing is present in the upper 27.4 m of the PB-3 borehole, thus 
precluding examination of the Nopal tuff. Fractures and cavities were identified in over 30 
intervals within the logged interval of PB-3 (DTN: LB0403PBTVXTRC.001 [168269]). An 
example of some of the fractures is shown in Figure I-6. The poorer quality of the PB-3 
televiewer log makes it difficult to pinpoint the location of the contact between the Coloradas 
tuff and the Pozos conglomerate units. There are several intervals within the PB-3 televiewer log 
in which angular clasts can be discerned (101.8102.4 m, 118.9119.8 m, 122.5123.7 m, and 
128.0129.2 m); these either represent lithic or pumice fragments within the Coloradas tuff or 
sedimentary clasts within the Pozos conglomerate. The static water level (Table 10.4-4) was 
encountered at a depth of 213.4 m, which is 1.5 m shallower than the depth indicated by the 
neutron log (214.9 m). The difference between these two measurements is most likely indicative 
of the relative error in the depth measurement between these two logging runs. 
I.4. PB-4 LOGGING RESULTS 
Unlike the other three new boreholes, PB-4 was a pre-existing well that had been cased with an 
8-in. steel liner down to a depth to 92.4 m and with an 8-in. slotted liner below. The presence of 
a liner in the well does influence the results of some geophysical logs and also precludes running 
resistivity logs. Log variations seen above and below 55-m depth in this well may reflect a 
change in lithology or could instead be an artifact of differences in well completion. There is no 
information available (from cuttings or core samples) that would allow for the direct 
determination of the stratigraphy of this well. 
Natural GammaNatural gamma values in PB-4 vary from 22175 cps. A zone of slightly 
elevated gamma values (typically 80130 cps) occurs between 55 and 96 m depth. Lower 
gamma values (~ 80 cps) were encountered within the SZ (the water table is around a depth of 
96 m). 
NeutronThere is a fairly restricted range of neutron log values throughout the UZ of PB-4, 
with most values ranging between 1,7002,600 API units. There is a zone with slightly higher 
than average neutron log values (2,3002,600 API units) between the depths of 27 and 54 m. 
The sudden drop in the neutron log at 96.5 m, where values decline from above 2,000 down to 
around 100300 API units, is associated with the location of the water table (Table 10.4-4). 
Density  The values of two different gamma-gamma density logs, SS and LS, were reported for 
PB-4 by CFE. The upper 55-m section of PB-4 exhibits significant variability in density values, 
with SS density values ranging from 1.1 to 3.5 g/cc and most values around 1.5 g/cc. Between 
55 m depth and the water table, density values are generally higher and less variable, typically 
ranging from 2.4 to 3.0 g/cc. At the water table, there is a noticeable rise in LS density values, 
with SZ LS density values increasing from values less than 3.0 g/cc to values typically ranging 
from 3.5 to 4.0 g/cc. 

TeleviewerThe well PB-4 contained casing down to a depth of 92.4 m, with slotted liner for 
the remainder of the logged section, thus precluding any examination of the geologic features. 
The static water level (Table 10.4-4) was encountered at a depth of 95.7 m, which is 0.8 m 
shallower than the depth indicated by the neutron log (96.5 m). The difference between these 
two measurements is most likely indicative of the relative error in the depth measurement 
between these two logging runs. 
I.5. REFERENCES 
I.5.1 Cited Documents 
168020 Ariceaga-Martinez, C.A. 2003. Drilling and Instrumentation of Three Piezometers, 
UACH Project, El Nopal Deposit, Wells: PB-1, PB-2, and PB-3, Final Report. 
Chihuahua, Mexico: Federal Commission of Electricity. ACC: 
MOL.200401008.0361. 
168021 Federal Commission of Electricity. 2003. Report on the Televiewer Log of the 
Boreholes PB-1 and PB-3 and Well PB-4 in Nopal, Municipality of Aldama, 
Chihuahua. Chihuahua, Mexico: Federal Commission of Electricity. ACC: 
MOL.20040108.0362. 
168019 Garay Jimnez, F.; Angn, R.P.; and Vargas, A.R. 2003. Study of Geophysical Logs 
in Four Wells Located in the Nopal Field, Aldama, Chihuahua, for the University of 
Chihuahua. Chihuahua, Mexico: Federal Commission of Electricity. ACC: 
MOL.20040108.0360. 
110223 Pearcy, E.C.; Prikryl, J.D.; and Leslie, B.W. 1995. Uranium Transport Through 
Fractured Silicic Tuff and Relative Retention in Areas with Distinct Fracture 
Characteristics. Applied Geochemistry, 10, 685-704. Oxford, United Kingdom: 
Elsevier. TIC: 246848. 
I.5.2 Source Data 
168014 LB0402PBCORELG.001. Core Description for PB-1. Submittal date: 02/27/2004. 
168016 LB0402PBDRLLGS.001. Drilling Log Descriptions for PB-1, PB-2, and PB-3. 
Submittal date: 02/27/2004. 
168017 LB0402PBGPHLGS.001. Geophysical Log Data for PB-1, PB-2, PB-3, and PB-4. 
Submittal date: 02/27/2004. 
168269 LB0403 PBTVXTRC.001. Pea Blanca Televiewer Log Extractions. Submittal date: 
03/11/2004. 

NOTE: Water table located at ~-222m. 
Source: DTN: LB0402PBCORELG.001 [168014]; DTN: LB0402PBGPHLGS.001 [168017] 
Figure I-1. Composite Lithologic and Geophysical Log of PB-1 

Source: DTN: LB0403PBTVXTRC.001 [168269]. 
Figure I-2. Zone of Intense Fracturing within the Nopal Tuff Section of PB-1 (5.2 m) 

Source: DTN: LB0403PBTVXTRC.001 [168269]. 
Figure I-3. Mineralized, Steeply-Dipping Fracture within the Coloradas Tuff at a Depth of 132.3 m in PB-1 

NOTE: Water table located at ~-215 m. 
Source: DTN: LB0402PBGPHLGS.001 [168017]; DTN: LB0402PBCORELG.001 [168014] 
Figure I-4. Composite Lithologic and Geophysical Log of PB-2 

NOTE: Water table located at ~-230 m. 
Source: DTN: LB0402PBGPHLGS.001 [168017]; DTN: LB0402PBCORELG.001 [168014]; DTN: 
LB0402PBDRLLGS.001 [168016]. 
Figure I-5. Composite Lithologic and Geophysical Log of PB-3 

Source: DTN: LB0403PBTVXTRC.001 [168269]. 
Figure I-6. Intersecting Mineralized Fractures within the Pozos Conglomerate at a Depth of 188.1 m 
in PB-3 

INTENTIONALLY LEFT BLANK