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Documentation of Program Change

INTRODUCTION
The U.S. Nuclear Regulatory Commission (NRC) disposal regulations, during this reporting 
period (FY 2001), are contained in 10 CFR 60.  The regulations in 10 CFR 60.21(b)(5) required 
that a repository license application must contain a description of site characterization work 
actually conducted by the U.S. Department of Energy (DOE) and an explanation of why such 
work differed from activities described in the Site Characterization Plan:  Yucca Mountain Site, 
Nevada Research and Development Area (SCP) (DOE 1988).  The Documentation of Program 
Change (DPC) is revised annually to update and document these changes.  The NRC recently 
promulgated its final rule on the Disposal of High-Level Radioactive Wastes in a Geologic 
Repository at Yucca Mountain, Nevada, as 10 CFR 63 (66 FR 55732).  This new rule (10 CFR 
63.21(b)(5)) retains the requirement that a repository license application contain a description of 
site characterization work conducted, but no longer requires a comparison with the original SCP 
(DOE 1988).  Nevertheless, the decision was made by the DOE to prepare Revision 04 of the 
DPC.  The scope of and need for future revisions of the DPC are currently being re-evaluated 
since 10 CFR 63  became effective on December 3, 2001.  Also, the DOE promulgated its final 
rule on Yucca Mountain Site Suitability Guidelines as 10 CFR 963 (66 FR 57298), and the EPA 
promulgated its final rule on the Public Health and Environmental Radiation Protection 
Standards for Yucca Mountain, Nevada, as 40 CFR 197 (66 FR 32074)1.
The SCP (DOE 1988) was developed in accordance with the Nuclear Waste Policy Act of 1982 
(NWPA), as amended, and has been the basis for the site characterization phase of the geologic 
repository program.  In 1989, the DOE assessed the progress and needs of the repository 
program and established a schedule that would result in a suitability determination for Yucca 
Mountain in fiscal year (FY) 2001, and if the site is suitable and a license granted, would result 
in start of disposal operations in FY 2010.  In parallel with the DOE assessment, the approach to 
underground characterization changed as vertical shaft and drift accesses were replaced by 
inclined ramps and drifts.  From 1989 to 1994, the DOE planned for and then conducted a 
comprehensive program of site investigations based on the SCP.
By 1994, external and internal factors had tended to broaden, rather than focus the program; 
Congress had also begun to express concern about continuing growth in the estimated cost of site 
characterization.  Furthermore, because the site characterization schedule did not call for 
definitive results until a license application was completed in 2001, progress was difficult to 
demonstrate or measure.  Thus in 1994, the DOE issued a revised Civilian Radioactive Waste 
Management Program Plan (Program Plan) (DOE 1994a) that was designed to show early 
observable progress with the financial resources likely to be available.  The program needed to 
be restructured, reorganized, and replanned in a manner that was simpler, more visible, and 
understandable to management and external oversight, and more flexible to respond to future 
changes.  Increasing scientific understanding, along with periodic total system performance 
assessment calculations, enabled focusing the ongoing site characterization program on the 
remaining uncertainties that are significant to the design, operation, and safe performance of the 
potential repository.  The previous approach to site characterization called for extensive testing 
to obtain a comprehensive understanding of the Yucca Mountain site to allow decisions to be 
made simultaneously on site suitability, licensing, and repository design issues.  Within the 
overall site technical program, the new approach distinguished among tests required to evaluate 
site suitability, to support licensing and define a cost-effective design, and to confirm the safety 
of the repository before closure.  This distinction permitted phasing of tests to achieve an earlier 
evaluation of whether Yucca Mountain appeared to be suitable and preserves the schedule for 
licensing, constructing, and operating the repository if the site were found suitable.  It also 
accommodates available resources.  As a result, a new, more flexible approach was developed, 
and site investigations were phased in such a manner that some of the original planned tests 
could be de-emphasized and others could be shifted to confirmatory status.  Previous progress 
reports have reported these changes as they affected study plans, design activities, and 
performance assessment plans.  The Civilian Radioactive Waste Management Program 
(Program) intends to continue evaluations and adjustments of work scopes as information needs 
evolve.
Congress endorsed the 1994 Program Plan (DOE 1994a) and provided a 37 percent increase in 
funding for FY 1995; subsequently, important progress was made.  However, guidance from 
Congress and a significant funding reduction in FY 1996 required another revision to the 
Program Plan, which was issued in May 1996 (DOE 1996a).  Under the funding reductions, the 
1994 Program Plan was no longer sustainable.  The Project was refocused to emphasize core 
scientific activity, which had continued to develop site characterization data and models 
throughout this period; excavation of sections of the Exploratory Studies Facility (ESF) 
necessary for scientific study; and completion of the repository and waste package conceptual 
designs.  Activities supporting the preparation and filing of a license application for the 
repository were deferred.  In FY 1997, the program was further focused on a 1998 assessment of 
the viability of geologic disposal at Yucca Mountain.  The NWPA, as amended, requires the 
Secretary of Energy to determine the suitability of the Yucca Mountain site as a nuclear waste 
repository and, if the determination is positive, forward a recommendation regarding siting of the 
potential repository to the President.
Reflecting these top-level program redirections in detailed annual and long-range plans was a 
major task during FY 1996.  With a baselined program in place at the beginning of FY 1997, 
documenting changes from the original plans presented in the SCP (DOE 1988) was a priority.  
Through the production of the 16th semiannual Site Characterization Progress Report:  Yucca 
Mountain, Nevada (DOE 1997a), progress reports provided links from the SCP to the 
requirements or planning documents that provide the basis for ongoing programs and have also 
documented changes to the site study and activity structure in the SCP.  The DPC, previously an 
appendix to the progress report and separated in 1998 as a stand-alone document, is intended to 
continue that documentation process by providing a status and rationale for changes in the design 
and performance assessment programs.  Most changes to the program will be found in the 
approaches to, amount of, and sequencing of field data collection activities.
While there have been noticeable changes to the repository and waste package design concepts 
since the Site Characterization Plan Conceptual Design Report (SNL 1987), there has not been a 
correspondingly large number of substantial changes in the technical information needed to 
design the repository and waste package.  The most significant change to the original conceptual 
design plans described in the SCP (DOE 1988) is the waste package.  That waste package was a 
thin-walled container designed to be emplaced in boreholes; current plans have shifted to a large, 
multi-barrier waste package that will be emplaced in large drifts.  A number of changes in the 
waste package design program are linked to this change.
Similarly, as additional information about the geotechnical character of the site has become 
better understood, and as system studies have examined alternative approaches to address 
10 CFR 60 requirements, the repository design concept has evolved to be responsive to this 
information.  For example, the SCP (DOE 1988) conceptual repository design (SNL 1987) was 
interfaced with the ESF design that used vertical shafts for access.  Current repository designs 
are integrated with the drift-based testing approach that has been used for the ESF.  These 
changes to the current repository design, while appearing to be substantially different from the 
conceptual design that served as the basis for the SCP, have resulted in few substantive changes 
in the definition of the technical information needed to design the repository.  While maturation 
in the understanding of constraints and design solutions has resulted in designs that are more 
responsive to 10 CFR 60 requirements, there has not been a concomitant large number of 
significant changes in the approaches embodied in the issue resolution strategies developed to 
address these regulatory requirements.
For performance assessment, changes in the regulatory framework together with new site and 
design information have increased our knowledge base so that improved approaches can be 
defined.  Many of these improved approaches have been discussed with NRC staff during 
technical interactions or summarized in previous progress reports.
This report is a continuation of documentation begun in Progress Report #15 (DOE 1997b), 
extended in Progress Report #16 (DOE 1997a), and produced separately in 1998 as 
Documentation of Program Change, Revision 00 (CRWMS M&O 1998a); in 1999 as 
Documentation of Program Change, Revision 01 (CRWMS M&O 1999f); in 2000 as 
Documentation of Program Change, Revision 02 (CRWMS M&O 2000a); and in 2001 as 
Documentation of Program Change, Revision 03 (CRWMS M&O 2001c).  The DPC provides a 
systematic review and documents the changes since the SCP (DOE 1988) was issued at a level of 
detail commensurate with the current planning basis.  Following this introduction, the changes in 
site investigations, repository design, waste package design, and performance assessment are 
discussed in turn.  The discussions first outline the background leading to the changes and then 
provide the current status for each study.
Progress Report #15 (DOE 1997b) summarized changes in the program since the issuance of the 
SCP (DOE 1988).  Additional detailed documentation of the rationale and justification for 
changes was provided in Progress Report #16 (DOE 1997a).  Revision 00 of the DPC (CRWMS 
M&O 1998a) provided an update of information for April 1, 1997, through September 30, 1997.  
Revision 01 of this document (CRWMS M&O 1999f) provided an update of information from 
October 1, 1997, through September 30, 1998.  Revision 02 of this document (CRWMS M&O 
2000a) provided an update of information from October 1, 1998, through September 30, 1999.  
Revision 03 of the DPC (CRWMS M&O 2001c) provided an update of information from 
October 1, 1999, through September 30, 2000.  This revision (Revision 04) provides an update of 
information from October 1, 2000, through September 30, 2001.
As part of the ongoing annual and long-range planning efforts, work plans are evaluated to 
ensure that the scope and schedule for activities will support the major milestones of the 
Program.
Annual updates to the DPC reports will provide rationale and justification for changes to the 
program as performance and design information matures.  Ultimately, the adequacy of the 
revised site characterization program will be judged on the basis of whether sufficient scientific 
and engineering information has been developed at each stage of the program to provide the 
technical basis necessary to support a decision on whether to continue the program.

1.	SITE PROGRAMS (SCP SECTION 8.3.1)
The Nuclear Waste Policy Act of 1982 and the high-level radioactive waste disposal regulations 
found in 10 CFR 60, specified that the DOE develop a Site Characterization Plan (SCP) 
(DOE 1988) before beginning any activities to characterize potential repository sites.  In 
addition, the disposal regulations specified that any potential license application will contain a 
description of changes to the site characterization program since the SCP was issued.  This 
requirement in 10 CFR 60.18(g) was the basis for the development of the Documentation of 
Program Change documents.  After the end of the reporting period for Revision 04 of this DPC, 
the NRC issued new disposal regulations (10 CFR 63) specific to the Yucca Mountain site 
(66 FR 55732), which no longer require a comparison with the original SCP.  
The SCP (DOE 1988) presented the initial general plan for the Yucca Mountain site and was 
based on then-available information about the site, and on then-current conceptual designs for 
the repository and the waste package.  The SCP was intended to provide the framework for all 
the site programs, but it was also intended to provide program flexibility.  The framework was to 
be augmented by study plans that were to be developed for each study and were intended to 
supply site-specific requirements for each study.  These plans were intended to describe the 
specific objectives of each study, specify the approaches and methods to be used to collect data, 
describe the accuracy and precision requirements for the data, and identify the uses for which the 
data were needed.
The SCP (DOE 1988) envisioned an extensive program of data collection designed to 
characterize the natural features and processes of the site, and reduce, or at least bound, the 
uncertainties associated with the various characterization parameters.  At the outset, the DOE 
recognized that it was initially committing to conduct a very large number of studies and that 
many of them would later be shown to be redundant or possibly unnecessary.  Thus, the SCP 
contemplated periodic revisions as the site characterization program matured.  The purpose of 
the program was originally to provide the scientific data needed to support the evaluation of site 
suitability and develop the license application for construction authorization.  As discussed in the 
introduction to this document, although the original purpose of the Project has been maintained, 
the Project was refocused to emphasize core scientific studies and excavation of those parts of 
the ESF needed for in situ scientific studies.  With completion of the ESF, the revised program 
strategy was designed to maintain momentum in scientific investigations, provide data needed to 
support the Viability Assessment, the site suitability recommendation to the President, and 
submittal of a license application to the U.S. Nuclear Regulatory Commission.
In planning the program described in the SCP (DOE 1988), the DOE adopted an approach that 
began with identifying the regulatory requirements that must be satisfied in siting and licensing 
the repository, identifying the performance and design information needed to address those 
requirements, and developing specific investigations to obtain the needed information.  This 
approach was embodied in an issue resolution strategy, which was discussed in some detail in 
Section 8.1 of the SCP.  An important part of this strategy was an issues hierarchy (discussed in 
Section 8.1.1 of the SCP and in the DOE Mission Plan (DOE 1985) that consisted of key issues, 
related issues, and information needs.  The key issues and related issues were based on the 
requirements in the disposal regulations.  The information needs defined the data and analytical 
techniques that were needed to resolve each issue.
The issues hierarchy stated questions about the performance of the disposal system and identified 
the information that would be required before a site could be selected and licensed.  The issues 
hierarchy was developed as a three-tiered framework consisting of key issues, related issues, and 
information needs.  On the highest tier were four key issues that embodied the principal 
requirements established by the regulations governing geologic disposal.  Each of the key issues 
was expanded, in the next tier, into a group of related issues that elaborated on the requirements 
stated in the parent key issue.  The lowest tier consisted of still more detailed sets of 
requirements called information needs that were associated with each issue.  This framework 
provided a convenient means to distinguish broad questions of overall performance and 
suitability (key issues) from more specific questions about the characteristics of the site, the 
design of the repository and the waste package, and the performance of the total geologic 
disposal system.  The framework also distinguished the key issues and related issues from the 
requirements for basic information needed to resolve the issues.
The investigations for the site characterization program have evolved based on the technical 
information obtained from laboratory and field studies, model development and data application 
activities.  Rapidly increasing scientific understanding, along with periodic total system 
performance assessment (TSPA), have enabled focusing the ongoing site characterization 
program on the remaining uncertainties that are significant to the design, operation and safe 
performance of the potential repository.  Re-evaluation and prioritization of Project needs has 
been a continuous process based on scientific judgment and resource availability, governed by 
scientific criteria to ensure that data needed for site description, performance assessment, and 
design purposes were collected and analyzed.  Data-collection that is redundant or no longer 
relevant has been eliminated.  The data-collection needs have been further analyzed and refined 
as additional knowledge has been gained through years of site characterization activities and 
analysis of site data.
In addition, major technical revisions to the repository program, including reconfiguration of the 
ESF from a shaft-and-main configuration to a ramp-and-main configuration, mechanical 
excavation of the ESF using a large diameter tunnel boring machine, and reconfiguration of the 
repository from vertical borehole emplacement to in-drift emplacement, required major revisions 
to the site programs.  The ramp-and-main configuration provided increased opportunities for 
observation of changes in stratigraphic, lithologic, and structural characteristics of the host rock.  
As a result, the strategy and methods for in situ mapping of fracture networks, faults, and 
lithostratigraphic features have changed considerably.  Most notable of these changes has been 
the acquisition of a large volume of data collected through detailed mapping of the ESF and the 
East-West Cross Drift.  Some questions about geohydrologic features and processes, inferred 
from the results of surface-based tests, could be answered by direct observation.  Because of the 
increased opportunities for direct underground observation and sampling, it was possible to 
reduce the scope of some surface-based testing activities.
Section 1 of this report is organized by individual site characterization programs.  For each 
program, background and SCP plans are summarized by study within each investigation.  
Subsequently, changes that have occurred, the basis for the changes, and the current status of 
each study are described.
1.1	GEOHYDROLOGY PROGRAM (SCP SECTION 8.3.1.2)
The geohydrology program was developed to provide an understanding of the groundwater 
environment that is essential to assessing the viability and suitability of the site.  Groundwater is 
expected to be the major transport medium of radionuclides to the accessible environment.  The 
general SCP strategy to accomplish the geohydrology program was to conduct investigations that 
would result in complete and accurate descriptions of the pertinent components of the hydrologic 
system.  The descriptions would reflect understanding of the hydrologic properties, initial and 
boundary conditions and processes, and their interrelationships.  The results of the geohydrology 
program were to be combined with the results of other site programs to produce a site model, or 
a complete description of the site.
The geohydrology program consisted of the data collection and evaluation activities that were to 
result in hydrologic models that describe two distinct regimes of the hydrologic system:  the 
unsaturated zone and the saturated zone.  Each of these regimes was to be characterized to 
provide input to the hydrologic models.  The unsaturated zone hydrologic model was to be 
developed only at the site scale, whereas the saturated zone models were to be developed at both 
site and regional scales.  The hydrologic regimes described by these models were to be those that 
significantly affect the resolution of hydrologic-related design and performance issues; these 
regimes, therefore, were to be the principal subjects of investigation in the geohydrology 
program.
The investigations included in the geohydrology program are summarized in the following 
sections.
1.1.1	Studies to Provide a Description of the Regional Hydrologic System (SCP 
Investigation 8.3.1.2.1)
Background and SCP Plans.  The objectives of this investigation were to develop a conceptual 
model of the regional hydrologic system to help assess the ability of the site to contain and 
isolate waste; and to construct a consistent, regional, numerical model of groundwater flow, so 
that reliable boundary conditions could be assigned to the more critical site area embedded 
within the regional model.  This investigation included four studies developed to accomplish the 
following:
1.	Study 8.3.1.2.1.1 (characterization of meteorology for regional hydrology):  This study 
was to: 
?	Characterize precipitation in the area surrounding Yucca Mountain and its 
relationship to surface run off, with particular emphasis on the Fortymile Wash 
drainage basin
?	Provide site-specific information on storm precipitation at and near the network 
streamflow-measurement sites as input to precipitation-run off models and to 
infiltration studies.
2.	Study 8.3.1.2.1.2 (characterization of run off and streamflow):  This study was to:
? Collect data on the characteristics, magnitudes, frequencies, and timing of 
surface-water run off at, and peripheral to, Yucca Mountain
? Develop an understanding of the relationships between specific run off events and 
the characteristics of the storms
? Provide calibration data for precipitation-run off models for the regional study 
area;
? Provide data and interpretations of surface-water run off for evaluations of the 
amounts and processes of groundwater recharge
? Document both quantitatively and qualitatively the characteristics of debris 
transported by intense surface run off and assess the potential for flood hazards 
and related fluvial-debris hazards.
3.	Study 8.3.1.2.1.3 (characterization of the regional groundwater flow system):  This 
study was to:
? Prioritize data needs for use in the regional groundwater flow description
? Determine the regional potentiometric distribution, including the cause of the 
large hydraulic gradient
? Characterize the regional hydrogeologic framework to support reliable estimates 
of groundwater flow direction and magnitude
? Use hydrologic, hydrochemical, and heat-flow data to determine the magnitude 
and direction of groundwater flow
? Determine to what extent (quantitatively, if feasible) Fortymile Wash has been a 
source of recharge to the saturated zone under present and past conditions
? Improve estimates of groundwater discharge by evapotranspiration in the 
Amargosa Desert to provide boundary-condition data for regional groundwater 
flow models.
4.	Study 8.3.1.2.1.4 (regional hydrologic system synthesis and modeling):  This study 
was to:
? Synthesize available data and identify groundwater flow system boundaries, 
hydrogeologic units, structural controls, and other hydrogeologic features 
pertaining to the regional groundwater flow system
? Update an existing two-dimensional, subregional, parameter-estimation mode
? Perform subregional, two-dimensional cross-sectional modeling to estimate 
groundwater flow direction and magnitude along a potential flow path through the 
repository block to the accessible environment and extending into the region
? Develop a comprehensive, regional, three-dimensional numerical groundwater 
flow model
? Use the regional model to test the impacts of possible future tectonic activity and 
climatic changes on the saturated hydrologic system.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The SCP, however, described a more extensive program of data 
collection.  The studies for this investigation have evolved based on technical information 
obtained from laboratory and field studies, model development and data application activities of 
the site characterization program.  Rapidly increasing scientific understanding, along with 
periodic TSPA, have enabled focusing the ongoing site characterization program on the 
remaining uncertainties that are significant to the design, operation and safe performance of the 
potential repository.  Re-evaluation and prioritization of Project needs has been a continuous 
process based on scientific judgment and resource availability, governed by scientific criteria to 
ensure that data needed for site description, performance assessment, and design purposes were 
collected and analyzed.  Data-collection redundancy and overlap have been eliminated.  The data 
collection needs have been further analyzed and refined as additional knowledge has been gained 
through site characterization activities.
1.	In the meteorology study (8.3.1.2.1.1), rainfall run-off models were not developed 
because direct relationships between precipitation and both infiltration (Hudson and 
Flint 1996, p. 1; Flint et al. 1996, p. 1) and recharge (Hevesi and Flint 1995, p. 1; 
DAgnese, Faunt et al. 1997, pp. 5056) were developed for hydrologic models using 
methods that did not require simulation of the run off component.  Also, because run 
off occurs so infrequently, it was determined to be infeasible to maintain readiness for 
run off monitoring with available Project resources.  Instead, the emphasis of the 
meteorology study was focused on analyzing regional and synoptic-scale weather 
patterns that impact infiltration at Yucca Mountain and on statistically analyzing the 
spatial variability of average annual precipitation as it relates to estimates of 
groundwater recharge for the regional saturated zone flow model.  Meteorological data 
collection and analysis activities were focused on determining the seasonality, 
duration, intensity, and spatial variability of storms that produce net infiltration in the 
many small watersheds that compose the Yucca Mountain site area.  To accomplish 
this, a network of full weather stations and tipping-bucket precipitation gauges was 
maintained through FY 1995 and then reduced in FY 1996 (CRWMS M&O 1995a, 
pp. 6.3-4 and 6.3-36; see also (Dixon 1996).  Operation of a reduced-intensity, 
site-area, meteorological data-collection effort is continuing.  The Radiological 
Environmental Programs Department operated the network during 1997 and 1998.  
The U.S. Geological Survey (USGS) resumed operating responsibility for the tipping-
bucket precipitation-gauge portion of the network in 1999 (see Section 1.9.2, Changes 
and Status).  In FY 2000, operation of the tipping-bucket precipitation-gauge network 
was assumed by the University of Nevada Las Vegas, Harry Reid Center under 
contract to DOE.  The M&O Integrated Analysis & Management group (formerly 
Radiological & Environmental Programs Department) retained operation of four full 
meteorological stations plus a limited number of additional precipitation gauge sites.  
This arrangement continued during FY 2001.
	The DOE believes that the site-area data collection effort will be adequate to provide 
data needed for the site recommendation and license application.  Whether additional 
precipitation data are needed was addressed, at least partially, by the sensitivity 
analyses performed as part of the Total System Performance Assessment-Viability 
Assessment (TSPA-VA) (DOE 1998a, Volume 3).  The TSPA-VA did not treat 
precipitation as a separate parameter because precipitation is a major component of the 
net infiltration model, the results of which were used directly in the TSPA-VA.  In 
general, the TSPA-VA results indicate that potential increases in confidence for net 
infiltration are related more to factors other than the distribution of present-day 
precipitation.  These factors include:
? Transitions from one future climate state to another
? Mean annual temperature during future climate states
? Timing and duration of future climate states
? Development of a more quantitative basis for uncertainty in net infiltration
? Consideration of other aspects of future climates that would affect net infiltration 
(cloudiness, vegetation, surface water run off-run-on, and snow cover)
? Enhanced calibration of the net infiltration model using well-documented present-
day analogs (DOE 1998a, Volume 3, Section 6.5.1.1).
	In the TSPA for Site Recommendation (TSPA-SR) (CRWMS M&O 2000af), 
precipitation was treated the same as it was in the TSPA-VA in that it is represented in 
flow fields that consist of three infiltration cases (lower, mean, and upper) within each 
of the three climate states (present-day, monsoon, and glacial-transition) (DOE 2001a, 
Section 4.2.1.4.1).  Uncertainties in net infiltration were evaluated in the Analysis of 
Infiltration Uncertainty (CRWMS M&O 2000ai), where precipitation was one of 12 
uncertain parameters.
2.	In the run off and streamflow study (8.3.1.2.1.2), regional-run off studies and data 
collection for precipitation-run off modeling were terminated before being fully 
implemented because the data were not needed for the regional groundwater-flow 
model (DAgnese, Faunt et al. 1997, pp. 4356).  Regional groundwater modeling did 
not require run off data for model calibration because data describing a direct 
relationship between precipitation and groundwater recharge was used.  In recent 
years, the emphasis of the streamflow study shifted to measuring the run off 
component of the water balance in small watersheds at Yucca Mountain in support of 
the unsaturated zone infiltration study (8.3.1.2.2.1) (Progress Report #9, 
Section 2.2.1.2 (DOE 1994b); Progress Report #13, Section 3.1.2 (DOE 1996b).  
However, because the net-infiltration component is so small compared with the run off 
component and because run off occurs so infrequently, this approach was abandoned 
after instrumenting only a few watersheds (Progress Report #14, Section 3.1.2 
(DOE 1996c)).  In FY 1998, four continuous-recording stream flow gauges on Split 
Wash and Pagany Wash were reactivated in anticipation of El Nio climatic 
conditions during the winter of 1997-1998 to provide data to validate and improve the 
coupled surface run off-infiltration module of the site-scale unsaturated zone flow 
model.  El Nio produced several winter storms that produced significant run off in 
these and other washes at Yucca Mountain during February 1998.  Run off data were 
collected at several sites.  However, at the end of FY 1998, all Yucca Mountain 
streamflow measurement sites were deactivated.
	Because flooding and fluvial-debris transport were shown by the Preclosure 
Hydrology Program (8.3.1.16) to pose little or no threat to the ESF, the potential 
repository (YMP 1995a, pp. 2-6, 2-11), or surface facilities at Yucca Mountain, studies 
to document transport of debris by severe run off were terminated before being fully 
implemented.
3.	In the regional groundwater system characterization study (8.3.1.2.1.3), the drilling 
program designed to resolve uncertainties in the regional potentiometric distribution 
(including the large hydraulic gradient) has not been implemented.  In particular, a 
deep hole in the Amargosa Desert intended to establish geologic control and obtain 
potentiometric-head data for the Paleozoic carbonate aquifer was not drilled.  Instead, 
data from sources outside the Project have been relied upon almost exclusively to 
characterize the regional hydrogeologic framework and the regional potentiometric 
surface for input to the three-dimensional, regional groundwater-flow model.  Despite 
the almost exclusive use of outside data, the three-dimensional groundwater-flow 
model was successfully developed and calibrated (DAgnese, Faunt et al. 1997, 
pp. 8694).  Recently, however, with support from the DOE Yucca Mountain Site 
Characterization Office (YMSCO), Nye County initiated a drilling and testing 
program in the saturated zone down-gradient from Yucca Mountain in the Amargosa 
Desert.  This program, called the Nye County Early Warning Drilling Program 
(EWDP), involves drilling a series of shallow and deep boreholes to obtain aquifer 
parameters, perform hydraulic testing, and conduct long-term water-chemistry and 
water-level monitoring (Stellavato 1997).  Fifteen shallow boreholes to depths of 
1000 feet are intended to obtain aquifer parameters for the alluvial and upper tuff 
aquifers.  Six holes, as much as 4000-feet deep, are intended to obtain hydraulic 
properties, geochemical, and water level information for the deep Paleozoic carbonate 
aquifer.  The EWDP boreholes are also intended to obtain data on the long-term 
effects of repository development.  Through FY 2001, most of the Nye County EWDP 
boreholes have been drilled, stratigraphic interpretations have been made, and 
hydraulic and tracer tests have been conducted in the alluvium.
	Although possible causes of the large hydraulic gradient have been identified through 
analyzing available geologic and geophysical data (Fridrich et al. 1994; Luckey 
et al. 1996, pp. 2125) and through hydraulic testing in well USW G-2, the cause of 
this feature remains an unresolved issue (Luckey 1996, pp. 2 and 3).  During FY 1997 
and FY 1998, additional field work and data collection were performed at borehole 
USW WT-24 in an attempt to further understand and characterize the large hydraulic 
gradient.  Drilling, water quality sampling, and testing of borehole USW WT-24, 
which is located within the large hydraulic gradient area north of the potential 
repository location, have confirmed that perched water exists on top of the Topopah 
Spring Tuff basal vitrophyre.  Further, deepening of borehole USW WT-24 into the 
Prow Pass Tuff revealed a tentative water level that seems to be consistent with the 
large hydraulic gradient.  Several alternate concepts for the large hydraulic gradient 
were considered during preliminary testing of the site-scale saturated zone flow model 
(Czarnecki et al. 1997, pp. 2629), including:
? Faults containing low-permeability gouge
? Faults juxtaposing transmissive and non-transmissive rocks
? An extensive perched water body
? A highly permeable fault that drains water from the upper part of the aquifer.
	In early FY 2002, a revision to the saturated-zone water-level analysis/modeling report 
was prepared to incorporate data from borehole USW WT-24 and apply an alternate 
concept for development of a potentiometric-surface map for the area north of Yucca 
Mountain where the large hydraulic gradient is located (USGS 2001c, Section 1). This 
concept assumes that water levels in boreholes USW G-2 and UE-25 WT #6 represent 
perched conditions, and are not representative of the regional potentiometric surface. 
By not using the data from those two boreholes and incorporating water-level data 
from borehole USW WT-24, the large hydraulic gradient is reduced from about 0.11 to 
between 0.06 to 0.07, and the potentiometric contours are more widely spaced (USGS 
2001c, Section 6.2).  Furthermore, potentiometric contours are not offset where they 
cross faults, as would not be expected where the contours are perpendicular or nearly 
perpendicular to the fault trace
	To date, because of time constraints and technical limitations of the simulation code, 
only the low-permeability fault gouge concept has been tested with the model.
	Although reconnaissance-level studies have determined that groundwater recharge to 
the saturated zone occurs in upper Fortymile Wash (Savard 1996; Luckey 1996, pp. 3 
and 4; Savard 1998), the field studies to quantify this recharge have not been 
conducted because they were determined to be of low priority (CRWMS 
M&O 1995a).  Similarly, although evapotranspiration feasibility and prototype work 
was performed (Progress Report #11, Section 3.1.3 (DOE 1995a)), the field studies to 
improve estimates of groundwater discharge by evapotranspiration in the Amargosa 
Desert have not been conducted.  Instead, estimates of regional groundwater recharge 
and discharge were improved using a modification of the Maxey-Eakin method.  This 
method uses a geostatistically derived distribution of average annual precipitation and 
a regional distribution of recharge potential based on elevation, vegetation, 
slope-aspect, and rock and soils permeability data obtained using remote-sensing and 
Geographic Information System techniques (DAgnese, Faunt et al. 1997, pp. 4356).  
With this approach, the three-dimensional groundwater flow model has been 
successfully developed and calibrated.
4.	In the regional hydrologic system synthesis and modeling study (8.3.1.2.1.4), updating 
of an existing two-dimensional, subregional, parameter-estimation model, developed 
in 1984, and two-dimensional cross-sectional modeling along a potential flow path 
have not been performed as separate activities.  However, much of the work scope 
intended for these activities is being accomplished by the development and testing of 
the regional, three-dimensional groundwater flow model (Activity 8.3.1.2.1.4.4).  The 
distribution of estimated values of hydraulic conductivity from parameter-estimation 
simulations of the model are regression estimates based on field data for the region 
(DAgnese, Faunt et al. 1997, pp. 106111), but the model still contains uncertainty.  
This is because field values of hydraulic conductivity range over two to three orders of 
magnitude for each rock type.  Overall, the range of hydraulic conductivity values for 
the entire model is more than seven orders of magnitude.  Furthermore, there are only 
about 20 potentiometric-level control points for the lowest layer of the model where 
most of the Paleozoic carbonate aquifer is represented.  Model simulations indicate 
that the hydraulic conductivity of the Paleozoic carbonate aquifer controls important 
features of the large hydraulic gradient (DAgnese, Faunt et al. 1997, p. 89).  Also, 
model results indicate that flow in the Paleozoic carbonate aquifer has substantial 
influence on flow in the overlying volcanic rocks.  Overall confidence in the 
simulation of the Paleozoic carbonate aquifer has been strengthened by good control 
on discharge from the aquifer through well-documented spring discharge data 
(DAgnese, Faunt et al. 1997, p. 86).
	The overall regional saturated zone flow system in the vicinity of Yucca Mountain 
appears to be controlled by the deep Paleozoic carbonate aquifer.  From a postclosure 
performance perspective, however, the overlying tuffaceous and alluvial aquifers are 
more significant because these would contain any likely travel paths for radionuclides 
moving between the potential repository and the accessible environment.  In addition, 
any future use of groundwater in the region would likely concentrate on the shallower 
tuffaceous and alluvial aquifers rather than on the deeper, albeit more transmissive, 
carbonate aquifer.  Results of the TSPA-VA indicated substantial uncertainty in the 
overall saturated zone flow system and the potential transport of radionuclides in the 
area between 10 km and 20 km down-gradient from the potential repository 
(DOE 1998a, Volume 3, Section 6.5.1.9), particularly where flow leaves the 
tuffaceous aquifer and enters the alluvial aquifer.  Additional water level, 
hydrochemical, and hydraulic-characteristics data are needed in this area to reduce 
uncertainty with respect to groundwater flow paths and transport properties.  These 
data needs are being met by studies being conducted as parts of the EWDP and at the 
Alluvial Testing Complex (see Section 1.1.3, Changes and Status, Item 1).
	A saturated zone flow and transport model abstraction and testing workshop was held 
April 1-3, 1997, in Denver, Colorado (CRWMS M&O 1997a).  The purposes of the 
workshop were to develop a comprehensive list of issues related to key uncertainties 
about saturated zone flow and transport behavior, prioritize the list of issues based on 
impact to long-term performance of the potential repository, and develop analysis 
plans to aid in the resolution of high-priority issues and provide a basis for model 
abstraction in TSPA-VA (CRWMS M&O 1997a, Executive Summary, p. x).  The 
categories of high-priority issues include conceptual models of saturated zone flow, 
conceptual models of saturated zone geology, transport processes and parameters, and 
coupling to other components of TSPA (CRWMS M&O 1997a, Table 1-1).  Analysis 
of the high-priority issues is continuing.
	Although large-scale anisotropy has not been characterized by field tests, regional 
structural features (major faults and fault zones) have been included in the regional 
model to improve its performance (see Section 3.1.4 of Progress Report #15 
(DOE 1997b) under Activity 8.3.1.2.1.4.4).  In an effort to increase confidence in the 
regional saturated zone model, the Yucca Mountain Site Characterization Project 
(YMP) model is being integrated with other DOE-sponsored work in southern Nevada, 
including the Underground Testing Area groundwater flow model.  The expanded and 
upgraded model is referred to as the Death Valley regional flow system.  In addition, a 
new set of boreholes is being drilled by Nye County in the Amargosa Desert along 
U.S. Highway 95.  These boreholes, which constitute the first phase of Nye Countys 
EWDP, are providing additional stratigraphic, water level, and hydrochemical data to 
reduce uncertainties in the regional flow model (see description of Changes and Status 
for Study 8.3.1.2.1.3.).  Furthermore, Nye County's EWDP has additional phases that 
include constructing monitoring wells along Fortymile Wash and the Alluvial Testing 
Complex (see Figure 1-1 and description of Changes and Status for Study 8.3.1.2.3.1 
in Section 1.1.3).  More detailed information about the Nye County EWDP is available 
on the Internet at http://www.nyecounty.com.  During FY 1998, regional groundwater 
modeling focused on refining the fluxes calculated by the model for use in the site-
scale saturated zone flow model, incorporating more vertical detail in the area down-
gradient from the potential repository, and improving estimates of discharge from 
regional springs and evapotranspiration areas.  In FY 1999, Death Valley regional 
flow system modeling efforts emphasized geologic framework compilations, 
refinement of input data sets, refinement of recharge estimates based on simulated net 
infiltration, comprehensive evaluation of water-level depth-interval data, and model 
calibration and evaluation.  In FY 2000 and 2001, a new regional hydrostructural map 
and the three-dimensional hydrogeologic framework model were completed.  In 
addition, three-dimensional, steady-state, numerical-model simulations of 
predevelopment conditions in the Death Valley regional groundwater flow system 
were conducted and documented.  As of the end of FY 2001, no specific plans had 
been developed to use the Death Valley regional flow system model to simulate 
Quaternary or possible future climatic conditions.  However, such plans are under 
consideration even though Quaternary and possible future climatic conditions have 
already been adequately simulated (DAgnese, Faunt et al. 1997).

Figure 1-1.  Map Showing Locations of Nye County Early Warning Drilling Program Wells
	Another change in the regional groundwater modeling study was the conduct of 
simulations of the hydrologic effects of possible future climatic conditions, originally 
planned under SCP (DOE 1988) Study 8.3.1.5.2.2.  The hydrologic effects of two sets 
of climatic conditions were simulated (DAgnese, Faunt et al. 1997) using the existing 
regional groundwater flow model (DAgnese, OBrien et al. 1997).  One simulation 
represented climatic conditions for 21,000 years ago, when glaciation was at a 
maximum.  The other simulation represented a possible future climatic condition when 
atmospheric carbon-dioxide concentrations might be doubled.  For the 21,000-years 
ago conditions, simulated water levels beneath the potential repository block were 
60 m higher than present-day levels.  Under the conditions of doubled atmospheric 
carbon dioxide, simulated water levels beneath Yucca Mountain were less than 50 m 
higher than present-day levels.
1.1.2	Studies to Provide a Description of the Unsaturated Zone Hydrologic System at the 
Site (SCP Investigation 8.3.1.2.2)
Background and SCP Plans.  The objective of this investigation was to develop a model of the 
unsaturated zone hydrologic system at Yucca Mountain that would help assess the suitability of 
the site to contain and isolate waste.  Developing this model requires an understanding of the 
manner in which water and gases move through the unsaturated zone, including the directions, 
paths, and rates in which flow occurs.  This information was to be provided through the 
characterization of infiltration, percolation, gaseous-phase movement, and hydrochemistry.  
Flow and transport modeling designed to simulate the natural system would provide sensitivity 
analyses to help prioritize additional data collection.  This investigation includes nine studies.  Of 
these, the first seven were data-collection studies; the last two were system-modeling studies.  
These studies were developed to accomplish the following:
1.	Study 8.3.1.2.2.1 (characterization of unsaturated zone infiltration):  This study was to:
? Characterize the infiltration-related hydrologic properties and conditions of the 
surficial soils and rocks covering Yucca Mountain
? Characterize present-day, natural infiltration processes and net-infiltration rates
? Characterize the range and spatial variability of infiltration rates, flow velocities, 
and flow pathways in the near-surface unconsolidated surficial material and 
consolidated bedrock, using double-ring infiltrometer and ponding studies 
(artificial infiltration activity)
? Characterize the relationship between precipitation, soil thickness, run off, 
infiltration, evapotranspiration, and development of perched water tables in the 
near-surface unconsolidated surficial material in each representative 
hydrogeologic surficial unit, using small-plot and large-plot rainfall simulation 
tests (artificial infiltration activity)
? Estimate the future spatial distribution of infiltration rate over the repository 
block.
2.	Study 8.3.1.2.2.2 (water-movement tracer tests):  This study was to characterize the 
percolation of precipitation into the unsaturated zone at Yucca Mountain, and the 
movement of water through the unsaturated zone, using chloride and chlorine-36 
measurements.
3.	Study 8.3.1.2.2.3 (characterization of percolation in the unsaturated zone
surface-based studies):  This study was to:
? Characterize and statistically describe the flux-related, matrix hydrologic 
properties of major unsaturated zone hydrogeologic units and structural features 
as functions of moisture content or potential through laboratory testing of 
geologic samples obtained from surface-based boreholes and from the ESF
? Determine the present vertical and lateral variation of percolation flux through the 
hydrogeologic units and structural features by measuring the potential field and 
determining the in situ bulk permeability of the unsaturated media in vertical 
boreholes throughout the site
? Evaluate the hydrogeologic significance of fracturing, brecciation, and gouge 
development within the Solitario Canyon fault zone by drilling and testing a 
horizontal borehole
? Investigate the relationships between present flux and past climatic conditions.
4.	Study 8.3.1.2.2.4 (characterization of percolation in the unsaturated zoneESF 
studies):  This study was to:
? Perform ESF hydrologic tests to supplement and complement the surface-based 
hydrologic information needed to characterize the Yucca Mountain site and to 
provide information for analyzing fluid flow and the potential for radionuclide 
transport through unsaturated tuff
? Combine the integrated results from the ESF hydrologic tests with data from the 
surface-based studies to provide an overall understanding of the unsaturated zone 
hydrologic system (ESF tests were designed to provide phenomenological 
information about water flow through unsaturated, fractured tuffs, in addition to 
providing basic hydrogeologic data)
? Conduct ten sets of hydrologic tests in the ESF:
(1) Intact-fracture testing to evaluate fluid-flow and chemical-transport properties 
of single, relatively undisturbed fractures
(2) Percolation testing to determine the hydrologic conditions that control the 
occurrence of fluid flow within fractures and matrix
(3) Bulk-permeability testing to determine representative characteristics of 
fracture networks for model simulations at the scale at which the fractured 
host rock behaves as an equivalent porous medium
(4) Radial-borehole testing to determine rock mass hydrologic properties 
(including bulk air permeability) and to detect vertical movement of liquid 
water and/or vapor within hydrogeologic units and along contacts
(5) Excavation-effects testing to monitor changes to both the stress state and 
fractured rock permeability caused by excavating and lining the ESF and to 
calibrate a coupled hydraulic-mechanical model
(6) Testing of the Calico Hills nonwelded hydrogeologic unit to determine 
hydrologic processes, conditions, and properties under both present and 
expected future conditions
(7) Perched-water testing to detect any occurrence of perched-water zones, 
estimate hydraulic properties of the zones, and determine the implications of 
perched water on flux, flow paths, and travel times
(8) Hydrochemistry testing to understand the gas transport processes; provide 
independent evidence of flow direction, flux, and travel time of gas and water; 
and determine the extent of water-rock interaction and the geochemical 
evolution of water
(9) Multipurpose-borehole testing near the ESF to monitor potential interference 
of ESF construction with ESF tests, identify perched water, and confirm 
engineering and hydrogeologic properties of the rock before ESF construction
(10) Testing of hydrologic properties and flow conditions of major faults 
encountered in the long drifts at the main test level of the ESF.
5.	Study 8.3.1.2.2.5 (diffusion tests in the ESF):  This study was to determine in situ the 
extent to which nonsorbing tracers diffuse into the water-filled pores of the tuffs of the 
Topopah Spring welded unit and the Calico Hills nonwelded unit in the ESF.
6.	Study 8.3.1.2.2.6 (characterization of gaseous-phase movement in the unsaturated 
zone):  This study was to:
? Describe the pre-waste emplacement gas-flow field and its effect on net water-
vapor transport from the unsaturated zone
? Identify structural controls on gas-phase flow
? Determine conductive and dispersive properties of the unsaturated zone for gas 
flow to assess potential transport of gaseous radionuclides (e.g., carbon-14)
? Provide the parameters necessary for modeling gas flow
? Perform model simulations of gaseous flux of moisture affecting deep percolation 
and transport of tracers in the gas phase.
7.	Study 8.3.1.2.2.7 (characterization of the unsaturated zone hydrochemistry):  This 
study was to:
? Perform hydrochemical investigations to understand gas-transport mechanisms 
and provide evidence of gas-flow direction, flux and travel time within the 
unsaturated zone
? Design and implement methods for extracting pore fluids from the tuff
? Provide independent evidence of flow direction, flux, and travel time of water in 
the unsaturated zone
? Determine the extent of the water-rock interaction and model geochemical 
evolution of water in the unsaturated zone.
8.	Study 8.3.1.2.2.8 (fluid flow in unsaturated, fractured rock):  This study was to
? Develop and validate (through ESF testing) detailed conceptual and numerical 
models of fluid flow and transport within unsaturated, fractured rock
? Apply these models to volumes of fractured rock at or below the dimensions at 
which the rock can be replaced conceptually by an equivalent porous medium
? Use the models to help design and interpret hydrologic and pneumatic tests and 
provide information about model parameters that can be incorporated into site-
scale models (Study 8.3.1.2.2.9).
9.	Study 8.3.1.2.2.9 (site unsaturated zone modeling and synthesis):  This study was to:
? Develop appropriate conceptual models for the site unsaturated zone 
hydrogeologic system
? Select, modify, or develop numerical hydrologic models capable of simulating the 
hydrogeologic system and its component subsystems
? Construct appropriate hydrologic models for the natural site hydrogeologic 
system to simulate and investigate the present state of the system and predict 
probable future and past states of the system under changes in the environmental 
conditions;
? Evaluate the accuracy and uncertainty of the models, using stochastic modeling, 
conventional statistical analyses, and sensitivity analyses
? Integrate data and analyses to synthesize a comprehensive, qualitative, and 
quantitative description of the site unsaturated zone hydrogeologic system under 
present as well as probable, or possible, future conditions.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP was issued.  The SCP (DOE 1988), however, described a more extensive program of data 
collection.  The studies for this investigation have evolved based on technical information 
obtained from laboratory and field studies, model development and data application activities of 
the site characterization program.  Rapidly increasing scientific understanding, along with 
periodic TSPA, have enabled focusing the ongoing site characterization program on the 
remaining uncertainties that are significant to the suitability of the potential repository site 
(DOE 1994a).  Re-evaluation and prioritization of Project needs (DOE 1994a) has been a 
continuous process based on scientific judgment and resource availability, governed by scientific 
criteria to ensure that data needed for site description, performance assessment, and design 
purposes were collected and analyzed, and to eliminate data-collection redundancy and overlap 
that would result from completion of all the studies in the SCP (DOE 1988).  The data-collection 
needs have been further analyzed and refined as additional knowledge has been gained through 
years of site characterization activities.  This process has resulted in the following changes to the 
investigation.
1.	In FY 1995, the unsaturated zone infiltration study (8.3.1.2.2.1) was reconfigured and 
accelerated (Progress Report #12, Section 3.1.5 (DOE 1995b)) in response to the site 
suitability initiative described in the Civilian Radioactive Waste Management 
Program Plan (DOE 1994a, Volume 1, pp. 1821), which was implemented to 
support a stepwise evaluation of the suitability or unsuitability of the Yucca Mountain 
site (DOE 1994a, Volume 2, p. 15).  Under the Program Plan, key evaluations were 
to be accelerated (compared to the SCP schedule) to focus more effectively on site 
suitability apart from all the considerations associated with the license application 
(DOE 1994a, Volume 1, p. 20).  In support of the suitability initiative, a Technical 
Basis Report on geohydrology and transport was scheduled for completion in 
FY 1998, requiring completion of an intermediate, integrated 
geology-hydrology-geochemistry model in FY 1997 (DOE 1994a, Volume 2, 
Figure 2-3).  Because the infiltration study was to develop the upper boundary 
condition for site-scale models of unsaturated zone flow and transport, the study had to 
be accelerated and reconfigured.  As a result, the artificial-infiltration tests described 
in the SCP were deferred, even though their primary purpose was to validate the 
numerical infiltration model that has been developed.  Consequently, although the 
numerical infiltration model is technically valid, it contains uncertainty with respect to 
important rock properties and processes at the alluvium-bedrock interface.

	The primary goal of the reconfigured study was to define the spatial and temporal 
distribution of moisture flux for the upper boundary condition for site-scale models of 
unsaturated zone groundwater flow and transport.  In this context, the boundary 
condition was developed as a conceptual and numerical model using arid-land 
watershed processes.  The model has provided a dynamic link between infiltration flux 
and known climatic variability, potential climatic trends, potential changes in the 
surface environment (such as loss of vegetation), and sporadic but extreme 
meteorological events.  The integration of hydrologic-process models for the surface 
and near-surface environments with mapped surficial-material hydrologic properties 
and mapped present-day net infiltration rates (as measured in the neutron-access 
boreholes) has resulted in a stochastic-deterministic simulation of future 
upper-boundary conditions, including the probability and magnitude of potential fast 
pathways of net infiltration.
	A surficial-materials infiltration-properties map of the Yucca Mountain area showing 
the spatial distribution of eight statistically significant soil units was developed, but the 
field and laboratory measurements used to produce the map were reduced both in 
number and in scope from that envisioned in the SCP (DOE 1988) because of the 
prioritization and accelerated schedule for the infiltration study.  The effects of the 
reduction on data representativeness and utility of the properties map have not yet 
been determined.  Moisture monitoring in the network of neutron-access boreholes 
was discontinued at the end of FY 1995, after 10 years of monitoring, because 
sufficient data had been collected for this phase of the Program.  A synthesis report 
was prepared in FY 1996 (Flint et al. 1996) using existing data to assess the current 
status of the study and to provide input for the Viability Assessment.  A multiple linear 
regression model was developed to correlate annual shallow-infiltration estimates 
measured in 69 neutron-access boreholes to annual precipitation, depth to bedrock, and 
other hydrogeologic factors (Hudson and Flint 1996, p. 1), but the series of 
double-ring-infiltrometer and ponding studies intended to determine the range and 
spatial variability of infiltration rates (artificial infiltration), were not conducted.  
Similarly, although one detailed water-balance study of Split Wash was initiated to 
develop and calibrate the evapotranspiration component of the infiltration model, the 
number and scope of watershed-scale studies was reduced considerably.  Further, the 
artificial infiltration control-plot studies were not implemented.  These studies would 
have measured water-potential gradients in the shallow subsurface (<15 m) under 
ambient conditions to determine the direction of water flow and the extent to which 
barometric pumping might be removing water in the vapor phase from the system.  
Finally, although a numerical model was developed to simulate the interaction of 
processes that result in net infiltration, the small- and large-plot rainfall-simulation 
tests (artificial infiltration) were not conducted; these tests were intended to validate 
the model with respect to temporal and spatial distribution of infiltration under both 
current-climatic and wetter conditions.  Specifically, these tests would have provided 
field data on rock properties and processes of the alluvium-bedrock interface to 
replace the available data that were collected from the alluvial surface and from deeper 
within the bedrock units.  At present, the Project has no plans to collect these data on 
rock properties and processes at the alluvium-bedrock interface.
	One of the objectives of the artificial infiltration experiments described in the SCP 
(DOE 1988) was to approximate the increased infiltration that might result from 
potentially wetter climatic conditions in the future by simulating those conditions in 
the field.  Even though the artificial infiltration experiments have not been conducted, 
monitoring of moisture flux in the neutron-access boreholes over the last 10 years has 
afforded an opportunity to observe a significant range of natural infiltration events.  
The termination of the neutron-moisture monitoring at the end of FY 1995 has 
precluded measurement of the subsurface redistribution of water that infiltrated during 
the larger storm events.  Subsurface redistribution of water may require several years.  
Nonetheless, as a result of several El Nio winter storm events over the last few 
winters (especially 1992, 1993, and 1995), unusually large precipitation events have, 
in fact, occurred and have provided useful insights about the potential effects of wetter 
conditions on infiltration rates.  These El Nio events are estimated to be analogous to 
the expected precipitation during global warming (due to increases in greenhouse 
gases) and possibly wetter pluvial periods in the future.  Although monitoring the 
vertical moisture profiles immediately following these events provided direct, 
qualitative evidence of the increased infiltration, in the absence of quantitative 
information on water potentials and fracture-matrix interactions at the 
alluvium-bedrock interface, longer term direction of flow (up or down), and therefore 
net infiltration, is not known with certainty.
	In the TSPA-VA (DOE 1998a, Volume 3), uncertainties about individual components 
of the infiltration model were not analyzed.  Instead, overall uncertainty about net 
infiltration was considered by running two performance-assessment simulations:  one 
with three times and the second with one-third the distribution of infiltration used for 
the base case (DOE 1998a, Volume 3, Section 3.1.2.2).  In general, the TSPA-VA 
results indicated that potential decreases in uncertainty for net infiltration are related to 
several factors including:
? Transitions from one future climate state to another
? Mean annual temperature during future climate states
? Timing and duration of future climate states
? Development of a more quantitative basis for uncertainty in net infiltration
? Consideration of other aspects of future climates that would affect net infiltration 
(cloudiness, vegetation, surface water run off-run on, and snow cover)
? Enhanced calibration of the net infiltration model using well-documented present-
day analogs (DOE 1998a, Volume 3, Section 6.5.1.1).
	For the TSPA-SR, completed in December 2000, the infiltration model was enhanced 
(CRWMS 2000af).  For example, uncertainty in estimated infiltration rates was 
addressed by simulating mean, lower-bound and upper-bound infiltration for the 
modern and two future climate states by using present-day analog climate sites.  In 
addition, the Project is focusing on determining the resulting percolation at the 
repository level and the potential for the Paintbrush nonwelded (PTn) hydrogeologic 
unit to divert flow laterally above the repository (Progress Report #17 (DOE 1998b, 
Section 5.2).
	During FY 1997 through FY 1999, work focused on enhancing the numerical 
infiltration model to reduce the uncertainty in some of its components.  Enhancements 
include development of a coupled net infiltration-surface-flow routing module, 
improved simulation of surface evaporation and root-zone transpiration, more accurate 
simulation of effective bedrock permeability, and inclusion of the effects of 
temperature in simulation of potential future climates.  In FY 1999 and FY 2000, the 
infiltration model was revised and used to simulate present-day climate conditions and 
two possible future climate states:  monsoonal and glacial transition (USGS 2001a).  
The revised climate scenarios for future climate were simulated with the infiltration 
model in order to realistically account for climate changes that are likely to occur 
during the next 10,000 years, which is the regulatory period for the potential 
repository.  To facilitate the input of infiltration values into the TSPA model, 
uncertainties in net infiltration were evaluated further in AMR Analysis of Infiltration 
Uncertainty (CRWMS M&O 2000ai).
2.	The water movement test study (8.3.1.2.2.2) was expanded considerably in scope and 
complexity from that outlined in the SCP (DOE 1988, pp. 8.3.1.2-1798.3.1.2-181).  
The expanded scope was intended to provide corroboration of borehole data, which 
were initially interpreted as indicating that pore waters were on the order of hundreds 
of thousands of years old.  Corroboration, if provided, was expected to support 
low-flux arguments.  The SCP indicated that sampling of tuffs for chlorine-36 would 
focus primarily on obtaining a profile in what was then planned to be a vertical shaft 
ESF.  Additional chlorine-36 measurements were to be performed on samples 
collected after a survey of Yucca Mountain to determine areas of active percolation.  
Since that time, the set of targets for sampling has expanded to include:
? Soil samples within the perimeter-drift boundary and from pits in Midway 
Valley
? Drill cuttings from the last set of neutron-access holes and deep systematic 
drilling, unsaturated zone and north ramp geologic boreholes
? Pore water extracted from cores of deep unsaturated zone and geologic boreholes 
in the ESF, East-West Cross Drift and Busted Butte Field Transport Facility
? Rain water and water from the bottom of neutron holes
? Perched water from several deep boreholes near the ESF
? Water samples from several deep saturated zone holes
? Water from springs and shallow wells in the Amargosa Valley and Death Valley
? Packrat middens (Progress Reports #6 through #15 (DOE 1992a, 1992b, 1993, 
1994b, 1994c, 1995a, 1995b, 1996b, 1996c, and 1997b)).
	With reconfiguration of the ESF into the ramp and drift configuration, the number of 
samples from the ESF and Cross Drift has increased substantially through systematic 
sampling along these tunnels and their niches and alcoves, and sampling of exposed 
discrete structural features that are potential fast-transport paths (Fabryka-Martin 
et al. 1997, Section 6.4).  The most significant aspect of this expanded sampling was 
finding elevated levels of chlorine-36 at several locations in the ESF and Cross Drift.  
These were attributed to the transport of bomb-pulse chlorine-36 to the sampled depths 
in less than 50 years.  The locations at which these elevated signals occurred appeared 
to be associated with faults.  The complexity of the study consequently increased by 
using the chlorine-36 method to investigate the spatial frequency of fracture flow, 
residence times of infiltrating water, and groundwater travel times.  In addition, the 
chlorine-36 results have been used in connection with the site-scale unsaturated zone 
transport model to estimate percolation flux at the repository horizon, to establish 
bounds on the ranges of hydrologic parameter values used in the site-scale model, and 
to develop and evaluate alternative conceptual models of flow and transport at the site.  
The study has also given increasing attention to the implications of pore water chloride 
concentrations as a surrogate measure of infiltration rates and as another 
environmental tracer useful for calibrating numerical flow models of the unsaturated 
zone.  For these reasons many of the samples selected for chlorine-36 analysis have 
also been analyzed for chloride contents.
	During FY 2000 and FY 2001, a chlorine-36 validation study was initiated and 
conducted because of concerns about possible contamination, representativeness of 
samples, lack of bomb-pulse chlorine-36 in the southern part of the ESF, and 
difficulties with replicating earlier analyses (DOE 2001c, Section 1.2.2).  As a part of 
the validation study, additional samples have been collected from the ESF and 
analyzed for chlorine-36 and tritium.  The validation study is expected to be completed 
during FY 2002.
3.	The percolation in the unsaturated zone surface-based study (8.3.1.2.2.3) has been 
reduced in scope in accordance with the priorities and planning assumptions for site 
investigations implemented for FY 1996 (CRWMS M&O 1995a, Volume 1, p. 6.3-1).  
The SCP (DOE 1988) indicated that 17 vertical boreholes would be drilled, tested, and 
instrumented in support of this study, 9 holes would penetrate to just above the 
potential repository horizon, and 8 holes would penetrate the unsaturated zone below 
the potential repository horizon.  Monitoring of pneumatic pressure, temperature, and 
water potential was to be performed in each hole for a minimum of 3 to 5 years.  
Although 16 holes have been drilled and used by this study, four of these were drilled 
along the alignment of the north ramp of the ESF rather than in the feature-based 
locations originally planned.  Of the 16 holes drilled, 8 terminated above the repository 
horizon and 7 penetrated to below the repository horizon.  However, no deep borehole 
has been drilled, or excavation made, to characterize the Ghost Dance fault in the 
Calico Hills Formation below the repository horizon.  No additional surface-based 
drilling is scheduled in this area in the Long-Range Plan (CRWMS M&O 1996a, 
p. A-6), except that which could be a part of confirmatory testing.  Perched water was 
detected in 7 of the 16 boreholes (CRWMS M&O 2000c, Section 8.5.2).
	Of the 16 holes drilled, 7 have been instrumented as planned to monitor pneumatic 
pressure, temperature, and water potential, while 2 holes were instrumented for 
pressure and temperature (Nye County), 2 for pressure only (flexible borehole liners), 
and 1 for vertical seismic profiling.  A significant change in the study has been the 
increased emphasis on the effects of ESF construction on the natural gas-phase system.  
This occurred because of commitments made to the NRC to perform pneumatic 
instrumentation and data collection in the vicinity of the ESF, prior to the passage of 
the tunnel boring machine, to characterize the pneumatic pathways of the mountain 
before the ESF cuts across possible pneumatic barriers (CRWMS M&O 1995a, 
Volume 1, p. 6.3-1).  Air-injection tests to determine gas-phase permeability have 
been conducted in 4 of the holes, only one of which penetrated below the repository 
horizon.  Air-permeability testing in surface-based boreholes was suspended because 
sufficient data have been collected to support this phase of the Civilian Radioactive 
Waste Management Program.  Further, no cross-hole pneumatic or gas-tracer tests 
have been conducted, and no additional pneumatic tests are planned.  Contrary to the 
SCP (DOE 1988), no boreholes have been drilled and tested on opposite sides of the 
Solitario Canyon fault or at the southern end of Yucca Mountain.  In FY 1999, 
borehole USW SD-6 was drilled from the crest of Yucca Mountain to obtain 
information about rock properties of the repository horizon and hydrologic data on the 
saturated zone.  The hole was drilled to a depth of 2,808 ft (855.9 m).  There are no 
plans to instrument this or other surface-based boreholes at the crest for hydrologic 
monitoring in the unsaturated zone or for vertical seismic profiling.
	Pneumatic and aqueous tracer tests in instrumented boreholes associated with the 
Solitario Canyon study have been deleted from the testing program, consistent with the 
revised program strategy described in the Program Plan (DOE 1994a, Volume 1, 
Appendix A, p. A-4).  However, many of the objectives of the Solitario Canyon fault 
horizontal borehole study are expected to be met by planned hydrologic testing in the 
cross drift being constructed as part of the Enhanced Characterization of the 
Repository Block (ECRB), also known as the East-West Cross Drift.  However, testing 
has yet to be implemented.  For more information on the ECRB cross drift, see the 
description of study 8.3.1.2.2.4 below.
	Although there are no additional surface-based boreholes planned to intersect the 
Ghost Dance fault, two test alcoves off the main ESF tunnel have been constructed, 
and horizontal boreholes drilled from these alcoves intersected the Ghost Dance fault.  
Much of the hydrogeologic testing planned for these boreholes has been completed 
(see Progress Report #17 (DOE 1998b, Section 5.2)).  Data from these tests were used 
to characterize hydrologic conditions in the vicinity of the fault at the repository 
horizon.  These hydrologic conditions have been used to constrain the unsaturated 
zone flow and transport models (Bodvarsson et al. 1997, pp. 7-27 through 7-33).
	From FY 1995 through FY 1998, monitoring of pneumatic pressure, temperature, and 
water potential continued in all seven instrumented boreholes.  During late FY 1998 
and early FY 1999, three boreholes were removed from the active monitoring network 
to reduce costs.  Monitoring in the other four boreholes continued through FY 2000 
and FY 2001.  After performing a detailed decision analysis in late FY 2001, the DOE 
decided to deactivate the remaining boreholes because no additional data were needed 
from them to support the site recommendation or the license application.  Following 
final equipment calibration and other close-out activities, the remaining four boreholes 
are expected to be deactivated by the end of the first quarter of FY 2002.
4.	In the percolation in the unsaturated zone ESF study (8.3.1.2.2.4), a number of 
changes in testing strategy resulted from reconfiguration of ESF from vertical shafts to 
ramps and drifts.  The multipurpose-borehole testing was deleted because of its 
association with vertical shafts and was replaced by the series of north ramp geologic 
holes and other boreholes.  The intact-fracture and excavation-effects tests have been 
terminated consistent with the strategy described in the Program Plan (DOE 1994a, 
Volume 1, Appendix A, p. A-4) because they would not lead to reduction in residual 
uncertainty in hydrologic parameters at the site scale.  The in situ testing for the 
bulk-permeability test has been combined with the radial-boreholes and major-faults 
tests, both of which are ongoing, consistent with the work-consolidation efforts 
implemented as part of FY 1996 planning (CRWMS M&O 1995a, pp. 6.3-51 and 
6.3-52).  The modeling part of the bulk-permeability test is being accomplished under 
Study 8.3.1.2.2.8 (fluid flow in unsaturated fractured rock).  Although the percolation 
tests on blocks of intact rock were deleted from the testing program, a reconfigured 
series of in situ field tests have been implemented.  These tests are continuing to 
estimate hydrologic properties of the faulted and unfaulted rock mass and the flux of 
water moving downward through the repository horizon in the ESF under present-day 
conditions.  These tests include the Ghost Dance Fault hydrologic testing, niche 
seepage studies, cross drift niche test, cross drift systematic hydrological 
characterization, Alcove 8/Niche 3 test, and the cross drift bulkhead and 
moisture-monitoring studies.  Testing of the hydrologic properties of the Ghost Dance 
Fault in the ESF is documented in LeCain et al. (2000).  In the niche seepage studies, a 
series of seepage-rate threshold tests were conducted at three niches along the ESF 
main drift during FY 2000.  The data were used for the development, calibration, and 
validation of the Seepage Calibration Model (CRWMS M&O 2001a) as it applies to 
the TSw middle nonlithophysal unit.  The cross drift niche test is being conducted to 
measure seepage and seepage thresholds in the TSw lower nonlithophysal unit.  The 
cross drift systematic hydrological characterization effort, started in May 2000, is 
utilizing slanted boreholes drilled into the crown of the cross drift at an interval of one 
borehole every 30 m.  The boreholes are used for determination of spatial 
heterogeneity of seepage potential and to measure effective porosity.  The Alcove 
8/Niche 3 test is evaluating seepage potential in a fault zone and the Cross Drift 
bulkhead and moisture-monitoring study is investigating the source of moisture 
(seepage or condensation) observed in sections of the cross drift that have been 
isolated from ventilation.  Progress in these studies is described in Progress Report 23 
(DOE 2001c) and in Section 3.3. of Progress Report 24 (in progress).
	Because perched water was never encountered in the ESF, the perched-water test was 
never implemented.  However, perched-water testing was conducted in surface-based 
boreholes under Studies 8.3.1.2.2.3 (Section 1.1.2) and 8.3.1.2.3.1 (Section 1.1.3).
	Extensive studies of secondary minerals deposited in the unsaturated zone and fluid 
inclusions within the minerals have been conducted and are continuing in the ESF and 
cross drift.  These studies are intended to determine the age of the deposits, source of 
the deposition water, temperature of the water, percolation flux associated with 
mineral deposition, distribution of flux in fractures and fault zones, and the overall 
response of the unsaturated zone to past climate changes.  These studies are 
summarized and statused in Section 1.4.2, Changes and Status, item 1.
	A test not anticipated in the SCP (DOE 1988) involving moisture monitoring in the 
ESF is under way.  This test is intended to develop a water mass balance for the ESF 
and to determine how much naturally occurring water is being removed from the ESF 
by the ventilation system.  In addition, two drift-scale seepage tests have been 
implemented in alcoves off the ESF main drift and north ramp.  The seepage test in the 
Southern Ghost Dance Fault Alcove (Alcove 7) is being conducted under close to 
natural conditions, in that the alcove was sealed from the rest of the ESF in 
December 1997 with a bulkhead to inhibit drying of the alcove by the ESF ventilation 
system.  A drip-detection system was installed in the Southern Ghost Dance Fault 
Alcove to monitor natural seepage into the alcove, which is located at the repository 
horizon about 200 m (650 ft) below land surface.  This seepage test was implemented 
just prior to a period of increased surface infiltration caused by above-normal 
precipitation because of El Nio climatic conditions.  The other drift-scale seepage test 
is being conducted under artificial conditions in the Upper Tiva Canyon Alcove 
(Alcove 1), which is only 35 m (115 ft) below land surface.  In this seepage test, water 
was applied artificially to the land surface using a drip-irrigation system to simulate 
wetter-than-normal climatic conditions.  This test was conducted to observe how a 
moisture front moves through fractured rock and how the drift itself influences 
percolation through the fracture network.  Results of the Alcove 1 seepage test are 
described in Progress Report 22 (DOE 2000a).
	Another major study in the ESF involved the East-West Cross Drift.  The cross drift 
was constructed from the ESF north ramp to the southwest about 2.8 km (1.6 mile) 
(CRWMS M&O 1997b).  The cross drift crosses over the main loop of the ESF, 
traverses the repository block from northeast to southwest, and then penetrates the 
Solitario Canyon fault system.  A series of five studies will be conducted in the cross 
drift:
? Geologic mapping of stratigraphy and structure
? Analysis of geotechnical and hydrologic rock properties
? Mineralogical analysis to estimate past percolation flux and flow paths
? Hydrological studies to assess the moisture conditions, identify preferential and/or 
fast flow paths, and assess effects of variable surface infiltration
? Predictive analyses.
	The predictive analyses involved preparation of a series of reports on the geology, 
hydrology, and geochemistry along the cross drift before excavation in order to help 
confirm and validate the general understanding of the repository block.  As noted 
above, extensive moisture monitoring is being conducted in the cross drift bulkhead 
and moisture-monitoring study.
	Discrete testing of the Calico Hills nonwelded (CHn) hydrogeologic unit in the ESF 
was deleted from the study plan in Revision 9 of the Yucca Mountain Site 
Characterization Program Baseline (YMP 1992).  However, testing in the CHn may 
be conducted as part of future testing activities in the cross drift.  To obtain early 
information on the CHn, a large-scale unsaturated zone transport test was started 
during FY 1998 within the Busted Butte facility about 6 km (3.6 mi) from the south 
portal of the ESF.  This two-phase test is providing information crucial to 
understanding radionuclide retardation and colloid migration in the Calico Hills 
Formation (Bussod et al. 1997, pp. 5-31, 5-39).  The test results also will help resolve 
scaling issues associated with the use of laboratory data to validate transport-model 
input for the Total System Performance Assessment.
5.	No diffusion tests have been conducted in the ESF (Study 8.3.1.2.2.5), and plans to 
conduct such tests have been suspended indefinitely.  Natural radioisotopes have been 
encountered in samples collected at several locations from the ESF and surface-based 
boreholes.  The occurrence of these naturally occurring (albeit possibly 
anthropogenically enhanced) tracers will continue to be used in conjunction with 
laboratory testing of matrix diffusion processes and parameters to define the role of 
matrix diffusion in the unsaturated zone radionuclide transport model.  In addition, 
tracer testing in the saturated zone at the C-hole complex has provided information, at 
the scale of several tens of meters, about the role of matrix diffusion in the tuffaceous 
rocks at Yucca Mountain.  Preliminary results of C-hole tracer tests completed in the 
Prow Pass Tuff (the uppermost unit in the saturated zone) indicate that matrix 
diffusion occurs, flow rates and hydraulic conductivity are very low, lithium sorption 
is greater than predicted by laboratory tests, and microsphere transport is reduced, 
indicating low hydraulic conductivity (Progress Report 20, Section 3.4 (DOE 1999b).
6.	Although the gas-phase movement study (8.3.1.2.2.6) has collected and used data from 
about a dozen more boreholes than was expected, the scope of work planned for key 
locations and boreholes has been reduced because not as many surface-based 
boreholes were drilled as anticipated by the SCP (DOE 1988), and because of a 
judgment that sufficient data have been collected to support this phase of the Program.  
Accordingly, the study investigators were requested to produce a synthesis report in 
FY 1996 (CRWMS M&O 1995a, p. 6.3-2) using existing data to assess the status of 
the study and provide input to the Viability Assessment.  The results of this study 
provide input to evaluation of the potential for transport of significant amounts of heat 
energy and water vapor from the rock mass into the atmosphere under both natural 
conditions and the thermal load associated with emplaced nuclear waste (Bodvarsson 
and Bandurraga 1996, Section 12.4; Patterson et al. 1996, p. 3).  Gas and water-vapor 
flow through the unsaturated zone are driven by changes in barometric pressure, 
temperature-induced density differences, and wind effects.  Preliminary evaluations of 
these mechanisms are described in Patterson et al. (1996, pp. 6775), Bodvarsson and 
Bandurraga (1996, Section 2.3.1), and Weeks (1993).
	Examples of reduced technical scope include the fact that neither the two vertical 
boreholes planned to straddle the Solitario Canyon fault nor the horizontal borehole to 
penetrate it were drilled.  Also, the cross-hole tracer tests planned for the USW UZ-9 
borehole complex have not been conducted because this cluster of boreholes has been 
deleted from the testing program.  Further, the extensive sampling of boreholes for 
chlorofluorocarbons to determine residence time of gas in the Tiva Canyon welded 
(TCw) hydrogeologic unit and to investigate possible breaches in PTn hydrogeologic 
unit was not conducted.
	A significant change from the original study strategy has been the use of the effects of 
ESF construction on the gas-phase system to estimate pneumatic properties of the 
unsaturated zone.  This occurred because of commitments made to the NRC to 
perform pneumatic instrumentation and data collection in the vicinity of the ESF, 
prior to the passage of the tunnel boring machine, to characterize the pneumatic 
pathways of the mountain before the ESF cuts across possible pneumatic barriers 
(CRWMS M&O 1995a, Volume 1, p. 6.3-1).  This was new work, identified since the 
SCP (DOE 1988) was issued.  The work was done to take advantage of the 
opportunity to use barometric responses to estimate large-scale pneumatic diffusivity 
in the ESF.  Specifically, a numerical gas-flow model of the ESF north ramp was 
constructed to simulate the progressive effects of excavating the north ramp as 
detected in nearby surface-based boreholes (Patterson et al. 1996, pp. 5067).  
A parameter-estimation technique was used to determine horizontal and vertical 
permeabilities of the Topopah Spring Tuff.  Although this preliminary, 
three-dimensional gas-phase modeling of the ESF north ramp area was done for this 
study, all remaining site-scale, gas-phase modeling will be done under 
Study 8.3.1.2.2.9.
7.	In the unsaturated zone hydrochemistry study (8.3.1.2.2.7), pore water has been 
extracted for hydrochemical and isotopic analysis from the cores of 9 of the 
15 boreholes drilled to support deep unsaturated zone studies (see item 3 above).  The 
scope of the hydrochemistry study was reduced because sufficient data have been 
collected to support this phase of the Program.  Accordingly, a synthesis report was 
produced in FY 1996 using existing data to provide input for the Viability Assessment 
(CRWMS M&O 1995a, p. 6.3-2).  Detailed, time-series gas-composition and 
isotopic-content data has been collected from borehole USW UZ-1, which is north of 
the repository.  Gas samples have been collected from 8 other boreholes, but in two 
instances the sampling was very limited (Yang, Rattray et al. 1996, pp. 4047).  
Further, gas samples have been collected from below the repository horizon in the 
Calico Hills Formation in one borehole (Yang, Yu et al. 1998, p. 4).  Overall, although 
inferences and conclusions regarding fluid movement have had to be based on fewer 
data from fewer locations in the vicinity of Yucca Mountain, the data collected are 
sufficient to meet the basic objectives and strategy for this study.
	Significant additional information on naturally occurring radioisotopes has been 
collected from the ESF.  These data have increased confidence in the unsaturated zone 
flow and transport models.  These data from the ESF combined with the borehole 
hydrochemical and isotopic data have been used to constrain these models.
8.	Because of significant changes in the ESF testing strategy (see item 4 above), the flow 
in unsaturated fractured rock study (8.3.1.2.2.8) has de-emphasized development of 
conceptual and numerical models solely for design and interpretation of small-scale 
ESF tests.  Instead, the study has concentrated on using all data available from the ESF 
to construct representative fracture-flow models at about the drift scale.  These 
models, particularly of the Topopah Spring welded (TSw) hydrogeologic unit, have 
provided a basis for calculation of the spatial distribution and magnitude of fracture 
flow that could seep into drifts of the potential repository (Tsang et al. 1997; CRWMS 
M&O 2000aj).  Evaluation of the fracture-network models is complete; it has been 
determined that one of the most appropriate models is the dual-permeability model, 
including both fracture and matrix continua.  This model has now been used as one of 
the main models for TSPA for both the drift-scale seepage model and the site-scale 
model.  In addition, as part of model development, a series of modeling approaches for 
small-scale flow phenomena have been applied directly to the unsaturated zone site-
scale model (Bodvarsson et al. 1997, Chapters 7, 21, and 24).  These include fracture-
matrix interaction modules, a hysteresis model, and an equivalent for unsaturated 
fracture models.  These approaches and models provide the theoretical and applied 
basis for evaluating various complex processes within the site-scale model.
9.	The site-scale unsaturated zone modeling and synthesis study (8.3.1.2.2.9) has 
exceeded expectations for simulation of the site-scale unsaturated zone system.  This 
has occurred, in part, because of significant advances in the numerical code and 
computer technology used in the modeling effort (Section 3.1.13, 
Activity 8.3.1.2.2.9.2 of Progress Report #15 (DOE 1997b); Progress Reports #7, #8, 
and #9, Section 2.2.1.13, Activity 8.3.1.2.2.9.2 (DOE 1992b, 1993, and 1994b)).  In 
addition, construction of the ESF ramp-and-drift configuration, during the time that the 
site-scale model was being developed, afforded an unexpected opportunity to calibrate 
the gas-phase part of the model.  Although it has been necessary to develop and 
calibrate the model with data from fewer surface-based boreholes than originally 
expected, data from instrumented boreholes documenting atmospheric-pressure 
fluctuations from ESF construction on the gas-phase system has made possible 
enhanced, large-scale, transient-state modeling of gas-pressure propagation through 
the mountain (Ahlers et al. 1995, Section 4).  These data have led not only to enhanced 
simulation of the gaseous phase but also to improved understanding and representation 
of fracture and fault diffusivities and permeabilities in the site-scale model.  Further, 
using temperature-gradient and heat-flow data for the unsaturated zone has led to 
enhancement of the ability of the model to simulate and predict moisture flow 
(Progress Report #15, Section 3.1.13, Activity 8.3.1.2.2.9.3 (DOE 1997b); Bodvarsson 
and Bandurraga 1996, Chapters 6, 8, and 9).  The model calibration has been further 
refined by using a variety of site information, including pneumatic pressures, 
saturations, updated data on the geologic framework, hydrologic properties, fracture 
and fault properties, vertical temperature variations, and perched water data.  
Hydrochemistry and isotopic ratios have also been considered.  Conceptual models for 
fracture-matrix interaction have also been incorporated.  The Unsaturated Zone Model 
utilized this calibrated hydrologic property set with a three-dimensional, steady-state, 
isothermal, dual-permeability modeling approach, including both fracture and matrix 
continua, to generate 39 flow fields for use by TSPA.  Enhancements are currently 
planned or underway, includingbut not limited tothe use of multi-dimensional 
inversions, continued updating of the hydrologic properties with new site data, and 
further development of the fracture-matrix interaction model.  During FY 1998 
through FY 2000, development of the unsaturated zone flow and transport model for 
TSPA-SR was completed, including coupled-processes and drift-seepage components.  
Complete descriptions of model development and results of simulations are 
documented in Unsaturated Zone Flow and Transport Model Process Model Report 
(CRWMS M&O 2000aq).  During FY 2001, components of the unsaturated-zone 
model were updated, including flow, transport, coupled processes, and drift seepage.  
Descriptions of the updated model components and results of recent simulations are 
described in the FY 01 Supplemental Science and Performance Analyses, Volume 1:  
Scientific Bases and Analyses (SSPA Vol. 1) (BSC 2001k).
	A major technical issue that has emerged since the SCP (DOE 1988) was written 
concerns the relation between site-scale percolation flux and the quantity of water that 
might seep into an individual drift in the potential repository.  Consequently, modeling 
of gas and water movement in the vicinity of a drift is receiving considerable emphasis 
(Tsang et al. 1997) (see also Progress Report #19, Section 2.3 (DOE 1999a); Progress 
Report #20, Section 3.3 (DOE 1999b); and appropriate sections of more recent 
progress reports).  Drift-scale modeling has been conducted and is continuing to:
? Incorporate results from various ESF hydrologic tests into the model for 
calculating the temporal and spatial distribution of fluxes near a drift
? Study the sensitivity of the model results to parameters not well established from 
measurements
? Calibrate modeling results against observations in the ESF and, in particular, 
recent niche experiments
? Estimate seepage locations and seepage flow rates at each location and for each 
realization of the drift model
? Incorporate the effects of near-field thermal and chemical alterations (i.e., calcite 
and/or silica precipitation cap)
? Simulate drift seepage for a number of alternative drift geometries, including 
rectangular and moderate step-like geometries.
	The results of recent drift-scale seepage and coupled-processes models are 
documented in Seepage Calibration Model and Seepage Testing Data (CRWMS 
M&O 2001a), Seepage Model for PA Including Drift Collapse (CRWMS M&O 
2000aj), and Drift-Scale Coupled Processes (DST and THC Seepage) Models (BSC 
2001i).
1.1.3	Studies to Provide a Description of the Saturated Zone Hydrologic System at the 
Site (SCP Investigation 8.3.1.2.3)
Background and SCP Plans.  The objective of this investigation was to develop a model of the 
saturated zone hydrologic system of Yucca Mountain that will help assess the suitability of the 
site to contain and isolate waste.  Developing this model requires an understanding of 
groundwater flow.  This understanding will be provided through studies focusing on the 
determination of boundary conditions imposed by structure, recharge, and discharge; hydraulic 
gradients in three dimensions; and bulk aquifer properties of units.  Modeling activities will use 
the resulting information to calculate groundwater flow paths, fluxes, and velocities within the 
saturated zone.  This investigation included three studies developed to accomplish the following:
1.	Study 8.3.1.2.3.1 (characterization of the site saturated zone groundwater flow 
system):  This study was to:
? Determine the hydrogeologic nature of the Solitario Canyon fault in the saturated 
zone
? Refine the spatial and temporal distribution of the potentiometric surface at the 
site to determine hydraulic gradients and groundwater flow magnitudes and 
directions
? Analyze water-level fluctuations to determine their causes and to estimate 
formation properties
? Analyze previously completed single- and multiple-well hydraulic-stress tests 
conducted in the C-holes to determine types of flow, hydraulic boundaries, and 
bulk hydraulic properties
? Conduct multiple-well interference testing in the C-holes to determine hydraulic 
properties, the appropriateness of anisotropic porous-media or fracture-network 
models, and the appropriateness of single-well or multiple-well tests
? Conduct single- and multiple-well conservative tracers tests at the C-holes and 
throughout the site to determine transport properties
? Conduct reactive tracer tests in the C-holes and throughout the site to determine 
properties of the geologic media that will affect retardation of radionuclides in the 
saturated zone.
2.	Study 8.3.1.2.3.2 (characterization of the saturated zone hydrochemistry):  This study 
was to:
? Describe the spatial variations in chemical composition of saturated zone 
groundwaters in the regional and site areas through analysis of representative 
water samples collected from wells and springs
? Describe the chemical and isotopic composition of the upper part of the saturated 
zone through analysis of representative water samples collected from the upper 
100 m of the saturated zone
? Conduct geochemical modeling to identify chemical and physical processes that 
influence groundwater chemistry
? Aid in the identification and quantification of groundwater travel times, climatic 
conditions during periods of recharge, and fluxes to and from the saturated zone 
by analyzing the chemical and isotopic compositions of interstitial-water and gas 
samples collected from immediately above the water table.
3.	Study 8.3.1.2.3.3 (saturated zone hydrologic system synthesis and modeling):  This 
study was to:
? Synthesize available data into a conceptual model and make a qualitative analysis 
of how the site saturated zone hydrogeologic system was functioning
? Develop fracture-network models for simulating groundwater flow and 
conservative solute transport and relate results of hydraulic and conservative-
tracer tests in wells to fracture-network characteristics
? Develop a comprehensive site-scale model of groundwater flow and transport to 
simulate groundwater flow direction and magnitude for input into travel-time 
calculations and evaluate the appropriateness of the porous-media and 
fracture-network concepts.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The SCP, however, described a more extensive program of data 
collection.  The studies for this investigation have evolved based on technical information 
obtained from laboratory and field studies, model development and data application activities of 
the site characterization program.  Rapidly increasing scientific understanding, along with 
periodic TSPA, have enabled focusing the ongoing site characterization program on the 
remaining uncertainties that are significant to the suitability of the potential repository site 
(DOE 1994a).  Reevaluation and prioritization of Project needs (DOE 1994a) has been a 
continuous process based on scientific judgment and resource availability, governed by scientific 
criteria to ensure that data needed for site description, performance assessment, and design 
purposes were collected and analyzed; and to eliminate data-collection redundancy and overlap 
that would result from completion of all the studies in the SCP (DOE 1988).  The data collection 
needs have been further analyzed and refined as additional knowledge has been gained through 
site characterization activities.  This process has resulted in the following changes to the 
investigation:
1.	In the site-scale saturated zone groundwater flow system study (8.3.1.2.3.1), the study 
of the Solitario Canyon fault in the saturated zone has not been conducted and is not 
included in the long-range plan.  This is a result of the judgment (CRWMS 
M&O 1996a, p. A-6) that Solitario Canyon fault is not considered as crucial to 
predicting movement of radionuclides in the saturated zone as are hydrogeologic 
features and conditions down-gradient from the repository area.  Although 14 of the 
planned 22 water table boreholes were drilled in the early 1980s, only one of the 
additional 8 water table holes described in the SCP (DOE 1988) has been drilled 
(USW WT-24).  Water table boreholes that have not been drilled include two for the 
Solitario Canyon fault study and a second to investigate the large hydraulic gradient.  
Some hydraulic tests have been conducted in borehole USW G-2, but these tests 
resulted in no new major understanding, and the nature and cause of the large 
hydraulic gradient remain unresolved.  Two possible hydrogeologic models for the 
large hydraulic gradient have been described by Fridrich et al. (1994).  As a result, 
estimates of saturated zone flux, flow velocities, and dilution beneath the site may 
differ considerably for different explanations of the cause of the large hydraulic 
gradient (Luckey 1996, p. 2).  During FY 2000 and FY 2001, a comprehensive 
analysis of site saturated-zone water levels was performed to provide the saturated-
zone, site-scale flow and transport model with the configuration of the potentiometric 
surface and to target water-level data for model calibration (USGS 2001b).  At the end 
of FY 2001, responsibility for maintaining the site water-level monitoring network 
was assumed by the University of Nevada Las Vegas Harry Reid Center.
	The Project has recognized the need for additional drilling to investigate the nature of 
the large hydraulic gradient.  Consequently borehole USW WT-24 was drilled and 
partially tested in an attempt to reduce the uncertainty associated with the existence of 
the large hydraulic gradient north of the potential repository site and to determine 
whether or not perched water exists in the area.  Water-quality sampling and hydraulic 
testing have confirmed that perched water exists on top of the Topopah Spring Tuff 
basal vitrophyre at the location of USW WT-24.  Further, deepening of borehole 
USW WT-24 into the Prow Pass Tuff revealed an apparent water level that seems to 
be consistent with the large hydraulic gradient.  (Note:  USW WT-24 was completed at 
a depth of about 2834 feet (864 m) on May 14, 1998.  For information on drilling 
progress, see CRWMS M&O 1998o.)
	Although the C-holes multiple-well interference and tracer tests have been conducted 
mostly as planned, not as many of the high-producing flow zones have been tested as 
originally planned, and testing at the low-producing zone will probably be limited 
(Progress Report #16, Section 3.1.14 (DOE 1997a).  To date, cross-hole hydraulic and 
tracer tests at the C-holes have been conducted in the lower part of the Bullfrog Tuff 
and the Prow Pass Tuff.  The Prow Pass tests were completed in February 1999 and 
data were submitted to the Project technical database.  In FY 2000 and FY 2001, final 
calibrations were obtained for equipment used in the C-holes tests (transducers and 
flow meters) and data packages were modified.  In addition, data, analyses, and 
interpretations from the C-holes hydraulic and tracer tests were compiled as input to 
the saturated-zone in situ-testing AMR, which is in preparation.
	C-holes testing was reduced in scope in accordance with the priorities and planning 
assumptions for site investigations implemented for FY 1996 (CRWMS M&O 1995a, 
Volume 1, p. 6.3-62).  In addition, the sequencing of testing has been modified so that 
hydraulic, conservative-tracer, and reactive-tracer tests are being conducted 
sequentially in a single flow zone before conducting any tests in the next flow zone.  
Although single-well hydraulic tests have been conducted in two water table holes 
(USW WT-10 and UE-25 WT#12), the results are of limited value (OBrien 1997, 
p. 35) because storativity data were not obtainable from the tests, and well-bore losses 
imparted additional uncertainties to the test results.  Therefore, no other single-well 
hydraulic or tracer tests are planned.  Instead, a second multiple-well test site has been 
drilled along a flow path south of the repository site, and the complex is now being 
called the Alluvial Testing Complex (ATC).  The multiple-well test site being 
considered is near the proposed 20-km compliance boundary (probably near 
U.S. Highway 95) and will be implemented cooperatively with the Nye County 
EWDP.  This test site offers the opportunity for hydraulic and tracer testing in the 
alluvium.  A few widely spaced wells were drilled in FY 1999 by Nye County, and 
one of these (NC-EWDP-19D1) was chosen for the ATC.  Additional wells were 
drilled in FY 2000 to obtain a closely spaced well cluster that allows hydraulic and 
tracer testing over reasonable time frames.  Hydraulic and tracer tests were conducted 
at the ATC during FY 2000 and FY 2001 to determine hydrologic properties and to 
measure the reduction in the concentration of solutes as they move through the 
saturated zone.  Results from the Nye County EWDP and the Alluvial Testing 
Complex are summarized in Section 3.4 of Progress Report 24 (in progress).
2.	In the saturated zone hydrochemistry study (8.3.1.2.3.2), the SCP (DOE 1988) called 
for intensive water and gas sampling from discrete intervals in 22 water table holes, 
14 existing and 8 new holes.  Hydrochemical testing was to include the clean out of all 
existing water table holes, extraction and analysis of interstitial water from cores of the 
new holes, and multi-element geochemical analyses of selected samples.  Although a 
few mixed-interval samples have been collected from two water table holes, the 
C-holes, and USW G-2, the site saturated zone hydrochemistry study remains only 
partially implemented.  Subsequent to the SCP, a plan was devised for in situ 
determinations of pH, Eh, and temperature in all 22 water table holes using a 
sophisticated downhole hydrochemical tool.  However, this plan was abandoned 
because of the high cost of the tool, uncertain potential for increasing knowledge, and 
the need to support critical saturated zone modeling efforts.  Although a limited 
number of water samples have been collected for chemical and isotopic analyses from 
springs during the regional study near Death Valley, the regional hydrochemistry 
study also remains only partially implemented.
	The saturated zone hydrochemistry study has not been implemented as planned 
because of the programmatic judgment (CRWMS M&O 1995a, Volume l, p. 6.3-66) 
that saturated zone hydrochemistry studies would have less impact on site suitability 
determinations than other studies and were therefore assigned a lower priority.  This is 
consistent with the strategy described in the Program Plan (DOE 1994a, Volume 1, 
Appendix A, p. A-4) that not all studies in the SCP (DOE 1988) would be completed 
before the suitability of Yucca Mountain is evaluated.  It should be kept in mind that 
the primary purpose of the saturated zone hydrochemistry study was to use 
hydrochemical and isotopic data to corroborate purely hydrogeologic evidence of 
regional and site-scale groundwater sources, recharge, fluxes, flow paths, and travel 
times.  Hydrochemical corroboration for regional flow paths has been adequately 
accomplished, as described below.  However, a similar evaluation at site scale may not 
be possible at present because of a lack of hydrochemical data from existing boreholes 
in the immediate vicinity of Yucca Mountain.  The importance of the hydrochemical 
corroboration at the site scale is debatable and does not currently have a high priority.
	In FY 1998, because the NRC announced its intention to issue new disposal 
regulations specific to Yucca Mountain (which ultimately became 10 CFR Part 63) 
that would be dose based, the Project re-evaluated the need for hydrochemical 
investigations in the saturated zone and implemented systematic hydrochemical 
sampling of wells down-gradient from Yucca Mountain.  The focus of this testing has 
shifted to the Nye County wells along U.S. Highway 95 and in the northern Amargosa 
Desert because of their proximity to the proposed compliance boundary.  
Consequently, hydrochemical and isotopic sampling of wells down-gradient from 
Yucca Mountain continued during FY 1999, FY 2000, and FY 2001 to help determine 
flow paths in the saturated zone.
	Regional hydrogeochemical information has been collected by other programs along 
the likely paths of regional groundwater flow.  The regional data, combined with the 
limited data collected under this study, have been used to enhance confidence in the 
regional groundwater flow model.  The geochemical signatures of greatest interest 
are distributions of major dissolved ions and stable isotope ratios that occur over large 
scales and are indicative of general mixing and geochemical evolution along regional 
flow paths.  Accordingly, following calibration of the regional groundwater flow 
model, general flow-path maps were generated from model output and superimposed 
over a series of maps depicting regional hydrochemical data.  Apparent hydrochemical 
evolution along major flow paths was evaluated qualitatively to corroborate the 
possibility or likelihood of the flow path generated by the model.  These evaluations 
were performed along general flow paths from major recharge areas (i.e., Spring 
Mountains, Pahute Mesa, Sheep Range) to major discharge areas (i.e., Ash Meadows, 
Oasis Valley, Furnace Creek Ranch).  Even though the hydrochemical-data sets along 
these major flow paths are somewhat incomplete and discontinuous, in general, the 
hydrochemical evaluation corroborated the flow paths generated by the flow model.
	To continue this analysis, a new activity was implemented in FY 1999 titled Isotopic 
and Hydrochemical Saturated Zone Studies with the principal objective of delineating 
saturated zone flow paths and establishing travel times down-gradient from the 
potential repository using hydrochemical and isotopic data.  The results of the initial 
phase of this activity are summarized in Progress Report 23 (DOE 2001c).  The results 
are being used to constrain and validate the regional groundwater flow model in terms 
of testing the credibility of model flow paths with regard to the chemical and isotopic 
parameters along these suggested pathways.  This effort continued in FY 2000 and FY 
2001 and is expected to continue for several more years.
3.	In the site saturated zone hydrologic system synthesis and modeling study 
(8.3.1.2.3.3), construction and calibration of a site-scale, porous-media-equivalent 
flow model is proceeding generally as planned, and a preliminary model has been 
completed (Czarnecki et al. 1997).  However, because of the application of 
sophisticated geographic information system and geologic-modeling techniques, the 
geologic framework model on which the flow model is based may be more rigorous 
and detailed than was envisioned when the SCP (DOE 1988) was issued.
	Although not completely calibrated, the final saturated zone, site-scale model will 
contain uncertainty for several reasons:
? Limited field tests have been completed to characterize the large-scale anisotropy 
because of a sparseness of hydraulic-test locations to serve as control points for 
model calibration
? Uncertainty persists about the cause of the large hydraulic gradient
? Uncertainty persists about fluxes at the northern model boundary because no 
potentiometric data are available in the Timber Mountain area to calibrate the 
regional model from which boundary fluxes are derived for the site-scale model
? Sparse hard data are available on the geometry and hydraulic properties of the 
Paleozoic carbonate aquifer underlying Yucca Mountain
? High quality chemical and isotopic data from the saturated zone are not sufficient 
to corroborate flow patterns.
	The degree to which these uncertainties in the saturated zone flow model might affect 
its use in TSPA was ascertained during the saturated zone flow and transport model 
abstraction and testing workshop, held April 1-3, 1997 in Denver, Colorado (CRWMS 
M&O 1997a).  The workshop identified and prioritized key uncertainties about 
saturated zone flow and developed analysis plans to aid in the resolution of 
high-priority issues.
	Alternative representations of the large hydraulic gradient north of the site were not 
addressed by an analysis plan (CRWMS M&O 1997a, pp. 1-12).  This is because it 
was the consensus of the workshop participants that these alternative representations 
would have little or no impact on the predicted concentrations of radionuclides 30 km 
down-gradient from the potential repository.  However, alternative representations of 
the large hydraulic gradient have been tested as part of the ongoing development and 
refinement of the site-scale saturated zone flow model.  If the potential impacts to 
onsite performance appear to be large from these alternative flow models, the 
alternative representations can be incorporated into the abstraction process at a later 
date (CRWMS M&O 1997a, pp. 1-12).  Abstractions are developed using a conceptual 
model that has a large hydraulic gradient.
	The Project also conducted a saturated zone flow and transport expert elicitation 
(CRWMS M&O 1998b).  The experts generally agreed that groundwater in the 
saturated zone flows from beneath the repository to the southeast and south primarily 
through fractured volcanic tuffs of the middle volcanic aquifer and the valley fill 
alluvium (DOE 1998a, Volume 3, Section 3.7.1.4).  Some panel members suggested 
that sorptive characteristics of the alluvium could significantly contribute to 
retardation of some radionuclides.  They expected faults and fracture zones to have 
important impacts on flow in the volcanic units.  The panel members offered 
alternative hypotheses for the large hydraulic gradient north of Yucca Mountain, and 
there was disagreement regarding the importance of this feature to repository 
performance.  The panel members did agree that any major transient change in the 
large hydraulic gradient is unlikely.  The panel members also generally concurred with 
interpretations of geochemical and paleospring data indicating water table rises of 80 
to 120 m (260 to 395 ft) beneath the repository in response to past climatic variations.
	For transport of contaminants in the saturated zone, the experts emphasized the 
limitations of processes that would cause dilution of contaminant concentrations.  The 
experts believe that transport would be by movement in vertically thin plumes through 
flow tubes beneath the repository.  Dilution of contaminants would occur by vertical 
transverse dispersion and transient fluctuations in the direction of the hydraulic 
gradient.  The experts generally rejected a mixed tank model in which contaminated 
flow from the unsaturated zone would mix on a large scale with uncontaminated 
groundwater in the saturated zone.  Consequently, the flow model, developed by 
Czarnecki et al. (1997), was not used for the TSPA-VA flow and transport 
calculations.  Instead, simulations of radionuclide transport in the saturated zone for 
the TSPA calculations were performed with six one-dimensional flow tubes using the 
FEHM code (V2.0 STN:  10031-2.0-00), which simulates heat and mass transfer for 
finite elements (DOE 1998a, Volume 3, Section 3.7.2).  Streamtubes are taken from a 
concept in classical fluid dynamics that is used to visualize and estimate the behavior 
of the elements of a flow system.  Each of the six streamtubes is a continuation of a 
groundwater flow path from the repository in the unsaturated zone.
	For TSPA-SR, the updated saturated zone flow and transport model (CRWMS M&O 
2000ak) was used to evaluate the migration of radionuclides from their introduction at 
the water table below the potential repository to the release point to the biosphere, 
which was assumed to be a hypothetical well down-gradient from the site (DOE 
2001a, Section 4.2.9.4).  This component of the analysis was coupled with the 
transport calculations for the unsaturated zone, which describe the movement of 
contaminants in downward percolating groundwater from the potential repository to 
the water table.  The input to the saturated zone flow-and-transport calculations is the 
spatial and temporal distribution of simulated mass flux at the water table that has 
been transported through the unsaturated zone.
	Although generic fracture-network-modeling techniques have been developed, a 
fracture-network model of the C-hole complex has not yet been developed because the 
extensive data that would have been required exceeded the data that could be 
collected.  Fracture-network models require intensive fracture mapping and 
characterization in order to develop a simulated fracture network that is statistically 
similar to the real network.  The level of detail required for the fracture data is on 
the order of that obtained in the ESF.  That degree of fracture characterization is not 
possible in vertical boreholes (even at the scale of the three C-holes) because of 
limited access to the rock mass and because of the bias introduced by boreholes 
intersecting subvertical fractures.  Although an exhaustive series of tracer tests might 
be possible to isolate and map individual fractures from one C-hole to another, such 
tests would be extremely time-consuming and very costly.  Moreover, fracture-
network modeling has been abandoned in general because analysis of field data and 
reasonable conceptual models of saturated zone flow at scales of interest (drawdown 
transients in the C-holes and in neighboring wells as far as 3.5 km) fit continuum 
analytic models.  Furthermore, dispersivities derived from tracer tests at the C-holes 
exhibit both continuum and non-continuum.
1.2	GEOCHEMISTRY PROGRAM (SCP SECTION 8.3.1.3)
The geochemistry program was intended to characterize site geochemical conditions and 
evaluate the effectiveness of the geochemical barriers that are expected to inhibit the transport 
of radionuclides away from the potential repository.  The program of geochemical testing 
described in the SCP (DOE 1988) concerned characterizing those areas of the site that lie beyond 
the altered zone (see Section 1.15 of this document).  The major purpose of the geochemistry 
program was to quantify the radionuclide retardation factor.  This factor was expected to be 
greater than one, and values greater than one were expected to provide added confidence to the 
calculations of transport to the accessible environment based on advective and dispersive 
transport calculations.
1.2.1	Studies to Provide Information on Water Chemistry within the Potential 
Emplacement Horizon and Along Potential Flow Paths (SCP 
Investigation 8.3.1.3.1)
Background and SCP Plans.  The objectives of this investigation were to provide a 
groundwater chemistry model that would explain the present groundwater composition as a 
result of interactions of the groundwater with minerals and be able to predict future variations in 
groundwater chemistry (under anticipated and unanticipated conditions) that could alter 
radionuclide flux through the saturated and unsaturated zone.  This investigation included one 
study developed to accomplish the following:
Study 8.3.1.3.1.1 (groundwater chemistry modeling):  This study was to develop pre- and 
post-emplacement groundwater chemistry models that would integrate the unsaturated and 
saturated zone data with the processes of water infiltration, water flow, and mineralogic changes 
to develop a mechanistic description of the current and future groundwater chemistry.  The study 
was also intended to consider changes in infiltration as influenced by climatic conditions; 
long-term mineralogic changes, particularly those influenced by the thermal pulse from 
emplaced waste; and changes in the material properties caused by the emplaced waste, or 
possible igneous activity.  These models have been integrated with several investigations in the 
geochemistry program.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP was issued.  The SCP (DOE 1988), however, described a more extensive program of data 
collection.  The studies for this investigation have evolved based on technical information 
obtained from laboratory and field studies, model development and data application activities of 
the site characterization program.  Rapidly increasing scientific understanding, along with 
periodic TSPA, have enabled focusing the ongoing site characterization program on the 
remaining uncertainties that are significant to the design, operation and safe performance of the 
potential repository (DOE 1994a).  Reevaluation and prioritization of Project needs 
(DOE 1994a) has been a continuous process based on scientific judgment and resource 
availability, governed by scientific criteria to ensure that data needed for site description, 
performance assessment, and design purposes were collected and analyzed.  Data-collection 
redundancy and overlap have been eliminated.  The data-collection needs have been further 
analyzed and refined as additional knowledge has been gained through years of site 
characterization activities.  This process has resulted in changes to the investigation.
In the groundwater chemistry modeling study (8.3.1.3.1.1), the number of laboratory 
experiments on water-rock interaction has been decreased, resulting in remaining uncertainty 
about the quantitative models of the processes that control water chemistry in the saturated and 
unsaturated zones.  To address a majority of these uncertainties, saturated zone hydrochemistry 
testing is under way both at Yucca Mountain and in the new Nye County EWDP wells.  This 
testing provides information about spatial variability in water chemistry, oxidation-reduction 
potential (Eh), pH, colloid content, and groundwater flow using both chemical and isotopic 
tracers.  The oxidation-reduction chemistry of the saturated zone may play a major role in the 
retardation of the very soluble radionuclides Np and Tc (see Section 1.2.4, Study 8.3.1.3.4.3).  
Uncertainties also involve the rate and manner in which volcanic glass is altered when it comes 
in contact with different water compositions.  Alteration of glass can strongly influence pH and 
the concentrations of other constituents in solution.
Information has been provided to studies of radionuclide retardation and transport.  Additional 
information on the solid phases involved in the alteration of volcanic glass would be needed to 
develop detailed deterministic models of groundwater chemistry.  The solid phases buffer the 
dissolved concentrations of major solutes which, in turn, influence the distribution of dissolved 
radionuclides.  A range of possible water and rock compositions, which may change with time, 
are expected to be encountered along the likely paths of radionuclide transport in the unsaturated 
and saturated zones.  Some of the compositional variation will likely result from 
repository-induced effects (e.g., temperature increases).  To the extent that these variations are 
known or predictable, they will be included in the hydrochemical model.  However, significant 
uncertainty regarding the identity of secondary phases and reaction kinetics involving these 
phases will remain.  The extent to which these variabilities and uncertainties affect radionuclide 
transport will be bounded in future TSPAs.  In FY 2000 and FY 2001, comprehensive reports on 
the geochemistry of the unsaturated and saturated zones were developed as input to TSPA-SR 
(BSC 2001j; CRWMS M&O 2001b).
1.2.2	Studies to Provide Information on Mineralogy, Petrology, and Rock Chemistry 
within the Potential Emplacement Horizon and Along Potential Flow Paths 
(SCP Investigation 8.3.1.3.2)
Background and SCP Plans.  The purpose of this investigation is to provide the baseline set of 
data and a basic understanding of the natural environment in which geochemical and other 
processes interact.  The objectives of this investigation are to determine the three-dimensional 
distribution of mineral types, compositions, and abundances in rocks beyond the host rock that 
provide pathways to the accessible environment; determine the timing, temperatures, and 
hydrologic conditions of past alteration at Yucca Mountain; study experimentally the

dehydration of smectite, zeolite, and glass; and use the results to develop descriptive and 
predictive models of mineral distributions along potential pathways to the accessible 
environment.  This investigation includes two studies developed to accomplish the following:
1.	Study 8.3.1.3.2.1 (mineralogy, petrology, and chemistry of transport pathways):  This 
study was to
? Determine the petrologic variability within the devitrified Topopah Spring Tuff at 
Yucca Mountain and define the stratigraphic distribution of variability
? Determine the three-dimensional distribution chemistry and total abundance of all 
major rock-matrix minerals between the host rock and the accessible environment
? Determine the distributions of minerals within fractures at Yucca Mountain.
2.	Study 8.3.1.3.2.2 (history of mineralogy and geochemical alteration at Yucca 
Mountain):  This study was to:
? Determine past temperatures from alteration mineral assemblages as a means to 
estimate the long-term thermal stabilities of important sorptive phases, such as 
clinoptilolite, and of the silica polymorphs that can influence water composition, 
precipitation, and the stabilities of other silicate minerals
? Investigate correlations between alteration mineralogy and rock hydrologic 
properties so that patterns of alteration can provide technical justification for 
choices of bounding and extrapolated property values used in numerical 
simulations
? Coordinate mineralogic and textural analysis with isotopic studies of groundwater 
percolation to promote understanding of fault, fracture, and matrix flow paths
? Determine how minerals and glasses in the rocks at Yucca Mountain will 
dehydrate and transform under expected thermal loads and investigate the ability 
of zeolites and smectites to rehydrate after the peak in temperature.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP was issued.  The SCP (DOE 1988, pp. 8.3.1.3-43 to -48), however, described a more 
extensive program of data collection.  The studies for this investigation have evolved based on 
technical information obtained from laboratory and field studies (Vaniman et al. 1996, 
pp. 641-646; Levy et al. 1996, pp. 785789), model development and data application activities 
of the site characterization program.  Rapidly increasing scientific understanding, along with 
periodic TSPA, have enabled focusing the ongoing site characterization program on the major 
uncertainties that are significant to the design, operation and safe performance of the potential 
repository (DOE 1994a).  Reevaluation and prioritization of Project needs (DOE 1994a) has been 
a continuous process based on scientific judgment and resource availability, governed by 
scientific criteria to ensure that data needed for site description, performance assessment, and 
design purposes are collected and analyzed.  Data-collection redundancy and overlap have been 
eliminated.  The data-collection needs have been further analyzed and refined as additional 
knowledge has been gained through years of site characterization activities (Vaniman et al. 1996, 
pp. 641-646; Levy et al. 1996, pp. 785-789).  In addition, resource constraints as Site 
Recommendation and license application approach, has led to termination of some mineralogic 
and petrologic work or deferral to the outyears.  This process has resulted in the following 
changes to the investigation:
1.	In the mineralogy, petrology, and chemistry of transport pathways study (8.3.1.3.2.1), 
the textural features within the devitrified Topopah Spring Tuff are no longer being 
quantified as a guide to determining variability within the potential host rock.  The 
method was cumbersome and prone to variability between operators conducting the 
activity.  However, quantitative X-ray diffraction and chemical data were still being 
obtained throughout the first part of FY 1999.  The technique of microautoradiography 
has been added both to the determination of waste interactions linked to mineral 
distributions between the host rock and the accessible environment and to work on 
transport related to fracture mineralogy, although no further work has been done with 
this method since FY 1998.  This addition was made to provide the detailed 
information on partitioning between minerals in specific rock samples of retardation 
potential for radionuclides, both for tuff matrix samples and for fracture samples.  
Significant effort through FY 1999 was devoted to the preparation, updating, and 
management of a comprehensive quantitative, three-dimensional model of mineral 
distributions at the site.  The first version of the 3-D Mineralogic Model was 
completed in FY 1997 (Chipera et al. 1997).  The latest version of the 3-D Mineralogic 
Model, Mineralogical Model (MM3.0) (CRWMS M&O 2000ar), was completed in 
FY 2000 to support the Integrated Site Model Process and Model Report (CRWMS 
M&O 1999i).
	The Mineralogic Model has been used to examine the composition and extent of 
zeolitized horizons and to prepare predictive reports of hazardous mineral occurrences.  
An important aspect of this model is the three-dimensional representation of site 
mineralogy.  The model supports a variety of applications including radionuclide 
transport modeling, dissolution and precipitation modeling, and modeling of mineral 
evolution under various thermal loads.
2.	In the history of mineralogic and geochemical alteration of Yucca Mountain 
study (8.3.1.3.2.2), the basic objectives did not change, but no activities have been 
funded within this study since FY 1998.  There was greater emphasis on determining 
the interrelationship between alteration and hydrology (e.g., Levy and Chipera 1997a, 
pp. 416).  A relative chronology of alteration was established, and the study then 
focused on some of the less well understood alteration, not explicitly identified in the 
SCP, but responsible for the distribution of existing hydrologic properties, particularly 
in the PTn hydrogeologic unit (Levy and Chipera 1997a, pp. 416).  Mineralogic 
characterization of PTn samples that have been used for hydrologic-property 
measurements made it possible to evaluate differences in moisture content, as 
determined by different methods because preliminary indications were that these 
differences correlate with hydrous mineral content.  Progress was made on a 
conceptual model of alteration in the PTn that could be used to predict the distribution 
of hydrologic properties within the unit, based on variations in mineralogic and 
hydrologic properties resulting from alteration processes (Levy and Chipera 1997a, 
pp. 127).  The conceptual alteration model was to be completed after acquisition of 
mineralogic data from drill holes that were to be drilled in FY 1999; however, this 
work was not funded.  The use of analytical geochronology was reduced from that 
originally planned because apparent ages determined by exploratory potassium-argon 
studies of zeolites were ambiguous and may not represent real ages.  Similarly, the use 
of electron spin resonance dating has been minimal because of a lack of a satisfactory 
commercial source of analytical services.  Although this technique may yet be used to 
confirm the timing of mineral deposition along groundwater flow paths.  Plans for 
petrofabric studies of zeolitic tuffs below the potential repository horizon were 
predicated on the availability of large oriented-block samples from an underground 
exploratory facility.  These plans were adapted to accommodate the use of drill core 
samples, which limits the data to cm-scale domains (Levy 1996, pp. 323), and 
evaluation of drill core samples.  Studies of the smaller samples revealed limited 
evidence for the channelization of fluid flow in partially zeolitized tuffs (Levy 1996, 
pp. 323).  The adaptations were necessary because the tunnel-boring machine did not 
enter the Calico Hills Formation, and no oriented-block samples were available.  Work 
related to the alteration history study plan objectives continues as part of the ESF 
thermal test program.  In particular, estimates of fracture-mineral abundance are being 
obtained to support numerical geochemical modeling of the thermal tests (Levy and 
Chipera 1997b).  Mineralogic data relevant to alteration history were also obtained for 
samples collected from the ESF for chlorine isotopic analysis.
	Heating studies of mineral and glass dehydration and transformation have proceeded 
largely as described in the SCP (DOE 1988, pp. 8.3.1.3-52 to -54), with a few 
exceptions.  Smectite and zeolites have been being studied, but no new data have been 
collected for manganese minerals and glasses.  The natural manganese minerals at 
Yucca Mountain have highly complex and variable chemical compositions and occur 
as intricate intergrowths of more than one mineral.  Efforts to date have emphasized 
studies of the volumetrically more abundant (and geochemically, more important to 
transport) clays and zeolites, yielding results that can be incorporated into numerical 
models of site thermal behavior and water budget.  Recent calorimetric results for 
clinoptilolite (Carey and Bish 1996; Carey and Bish 1997) have been incorporated into 
simplified thermohydrologic models of Yucca Mountain.  These models show that the 
presence of zeolites has the effect of reducing the maximum temperatures reached by 
the rocks, because of the high enthalpy of dehydration for zeolites.  Planned 
experiments to heat minerals in a steam environment could not be maintained on a 
long-term basis with existing laboratory apparatus (Bish and Chipera 1994).  Steam 
heating tests that had been planned under Study 8.3.1.20.1.1 (Altered Zone 
Characterization) and Study 8.3.4.2.4.1 (Characterize Chemical and Mineralogical 
Changes in the Post-Emplacement Environment) were terminated, because the 
reaction vessels would not hold steam for sufficient periods of time.
1.2.3	Studies to Provide Information Required on Stability of Minerals and Glasses 
(SCP Investigation 8.3.1.3.3)
Background and SCP Plans.  The goal of this investigation is to determine the stability of 
minerals and glasses along the flow paths to the accessible environment to assess impacts of 
waste emplacement on mineral stability and the resulting effect on radionuclide retardation.  The 
objectives of this investigation include testing the capabilities of the EQ3/6 
(V7.2b STN:  11066-7.2b-00) geochemical code, improving the reliability of long-term 
predictions regarding hydrothermal rock alteration in devitrified welded ash flow tuff, and 
improving the understanding of the origin of alteration mineral assemblages found in Yucca 
Mountain; investigating the kinetics of glass and silica polymorph transitions and their 
relationships to aqueous silica activity, and providing thermodynamic data for clinoptilolite-
heulandite and albite and analcime; and developing a conceptual model of mineral evolution.  
This investigation included three studies developed to accomplish the following:
1.	Study 8.3.1.3.3.1 (natural analog of hydrothermal systems in tuff):  This study was to 
improve the reliability of long-term predictions regarding hydrothermal rock alteration 
in devitrified welded ash-flow tuff using studies of occurrences of natural analog 
hydrothermal systems in tuffs.
2.	Study 8.3.1.3.3.2 (kinetics and thermodynamics of mineral evolution):  This study was 
to:
? Predict the rates of possible transformation of silica polymorphs in Yucca 
Mountain and the effects such transformations would have on aqueous silica 
activity
? Determine the end-member free energies from solubility measurements of 
clinoptilolite-heulandite, albite, and analcime
? Describe the thermodynamics of the clinoptilolite-heulandite and analcime solid 
solutions in support of development of the mineral stability model.
3.	Study 8.3.1.3.3.3 (conceptual model of mineral evolution):  This study was to produce 
a conceptual model to explain the observed distributions of minerals in Yucca 
Mountain, address the general chemical evolution of vitric tuffs, and predict future 
mineral evolution in the mountain caused by both natural processes and the 
emplacement of radioactive waste.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The SCP, however, described a more extensive program of data 
collection.  The studies for this investigation (Study Plan 8.3.1.3.3.2) have evolved based on 
technical information obtained from laboratory and field studies, model development and data 
application activities of the site characterization program (Carey et al. 1996, p. A-469).  Rapidly 
increasing scientific understanding, along with periodic TSPA, have enabled the ongoing site 
characterization program to prioritize the remaining uncertainties that are significant to the 
design, operation and safe performance of the potential repository (DOE 1994a).  Reevaluation 
and prioritization of Project needs (DOE 1994a) has been a continuous process based on 
scientific judgment and resource availability, governed by scientific criteria to ensure that data 
needed for site description, performance assessment, and design purposes were collected and 
analyzed.  Data-collection redundancy and overlap have been eliminated.  The data-collection 
needs have been further analyzed and refined as additional knowledge has been gained through 
years of site characterization activities (see Study Plan 8.3.1.3.3.2, and Carey et al. 1996, 
p. A-469).
1.	The natural analog of hydrothermal systems in tuff study as described in the SCP 
(DOE 1988) has not been initiated as part of Study 8.3.1.3.3.1, but natural analog 
studies were conducted within work package 14012122M6, Natural Analog 
Investigations, which investigated evidence of hydrothermal alteration of tuffs by an 
intruding sill at Paiute Ridge, Nevada Test Site and the thermally induced changes in 
permeability within cores taken from the Yellowstone geothermal field.  Results of 
these studies will be reported in the AMR on natural analogs for the unsaturated zone.  
The potential performance-related implications of possible hydrothermal alteration of 
tuffaceous rocks include the flow and transport characteristics along the likely paths of 
radionuclide transport between the potential repository and the water table.  The 
resultant changes are likely to affect the hydrologic properties of the altered rocks 
(permeability and porosity) and the retardation characteristics of the mineral 
assemblages.  In addition, repository-induced alterations of the host rock could result 
in changes to the mechanical properties of the rocks, particularly in the region 
immediately surrounding the repository horizon.  Initial indications are that such 
alterations cause changes in the retardation coefficients along potential transport 
pathways.  These changes are outside of the expected natural variability observed in 
the characterization program for rocks along potential flow paths to the water table 
(Carey et al. 1996, p. A-469; Carey et al. 1997, p. A13).  Given that the changes are 
outside the bounds of natural variability, the need to confidently determine the 
reliability of any particular water-rock interaction model using natural analogs 
continues.  The reliability of models of water-rock interactions has not been 
determined using natural analogs.  Such activities have been outside the scope of work 
in development of the conceptual model of mineral evolution under Study 8.3.1.3.3.2.
2.	The kinetics and thermodynamics of mineral evolution study (8.3.1.3.3.2) was 
combined with the study on conceptual model of mineral evolution (previously 
8.3.1.3.3.3) (see Study Plan 8.3.1.3.3.2).  The combined study was unfunded and is 
inactive.  These studies were combined to integrate the experimental and modeling 
aspects of mineral evolution and to create the necessary ties between experiments and 
performance models.  The conceptual model integrates results of the kinetics and 
thermodynamics studies with the Projects three-dimensional mineralogic model to 
predict the long-term effects of a repository on the rocks and minerals at Yucca 
Mountain.  Efforts to investigate glass reactions are no longer planned because these 
studies are now parts of Studies 8.3.1.20.1.1 (Altered-Zone Characterization) and 
8.3.4.2.4.1 (characterize chemical and mineralogical changes in the post-emplacement 
environment).  Studies on the dissolution and precipitation kinetics of zeolites were 
expanded to include an experimental component because insufficient site- and 
mineral-specific data are available in the literature.  These studies included 
clinoptilolite, mordenite, illite-smectite, and analcime.  Solubility studies to provide 
zeolite free energies were augmented to include mordenite, but these studies did not 
consider albite because sufficient data existed.  The data reduction codes listed in the 
SCP (DOE 1988) under this activity were not used, because more modern and 
comprehensive codes exist including YMSCO-approved codes such as EQ3/6 and 
FEHM (see Study Plan 8.3.1.3.3.2).  Efforts to describe the thermodynamics of zeolite 
equilibria were expanded to include mordenite and other minor zeolites at Yucca 
Mountain such as erionite, chabazite, and phillipsite.  These efforts have produced the 
most up-to-date picture of the thermodynamics of zeolite equilibria available 
(Carey et al. 1997, p. A13; Chipera and Bish 1997, p. A15).  For the first time, a 
complete picture of natural zeolite equilibria as a function of temperature, water 
composition, and zeolite composition is available.  The thermodynamic modeling 
efforts were based on calculated thermodynamic data for individual zeolite species 
because sufficient experimental data were unavailable.
3.	The study on conceptual model of mineral evolution (previously 8.3.1.3.3.3) was 
combined with the kinetics and thermodynamics of mineral evolution study 
(8.3.1.3.3.2).  See description under item 2 above.
1.2.4	Studies to Provide the Information Required on Radionuclide Retardation by 
Sorption Processes Along Flow Paths to the Accessible Environment 
(SCP Investigation 8.3.1.3.4)
Background and SCP Plans.  The purpose of this investigation was to obtain data on the 
sorption behavior of key radionuclides (americium, carbon, cesium, curium, iodine, neptunium, 
plutonium, strontium, technetium, uranium, and zirconium).  The objectives of this investigation 
were to obtain sorption coefficients for key radionuclides as functions of the composition of 
groundwater, substrate compositions and structures, acidity (pH), reduction-oxidation potential 
(Eh), and other parameters; evaluate effects of microorganisms on the movement of radioactive 
waste, and determine whether microbial activities play a role significant enough to be included in 
performance calculations; and model the sorption experiments on rocks and minerals 
representing the potential repository block and derive a capability to predict sorption coefficients 
for key radionuclides under water-rock conditions not included within the experimental program.  
This investigation included three studies developed to accomplish the following:
1.	Study 8.3.1.3.4.1 (batch sorption studies):  This study was to
? Determine sorption coefficients for radionuclides on tuffs of the Calico Hills 
Formation zeolitic and vitric units, on devitrified tuffs, and on pure minerals 
representative of the minerals present in the rocks and fractures of the repository 
block
? Characterize the dependence of sorption coefficients upon the concentration of the 
element being sorbed by developing isotherms for the radionuclides
? Measure sorption coefficients as functions of groundwater compositions 
anticipated along potential travel paths and determine if the values of Kd were 
above specified values
? Determine if sorption of important radionuclides occurs along particulates or 
colloids that may be present in groundwaters along potential transport pathways
? Produce statistical correlations and error estimates.
2.	Study 8.3.1.3.4.2 (biological sorption and transport):  This study was to quantify the 
locations and characteristics of past and potential future organic materials used at the 
site and their susceptibilities to microbiologic degradation by determining the growth 
of microorganisms in fluids such as drilling fluids, evaluating the influence of 
microorganisms on the movement of actinides by mechanisms such as colloidal 
agglomeration and chelation, and determining the binding constants of 
microorganisms to actinides.
3.	Study 8.3.1.3.4.3 (development of sorption models):  This study was to model the 
sorption experiments on rocks and minerals representing the potential repository block 
and to derive a capability to predict sorption coefficients for key radionuclides under 
water-rock conditions not included within the experimental program; and develop the 
best possible capability for predicting sorption coefficients for key radionuclides in the 
potential repository block using the available data.
Changes and Status.  No significant changes in these studies have been made since the SCP 
(DOE 1988) was issued, but this study has not been funded since November 1998.
1.	The batch sorption study (8.3.1.3.4.1) is virtually complete, and the work is generally 
consistent with the description in the SCP.  Work remains to complete the data set for 
plutonium.  This work on plutonium has been complicated by the multiple oxidation 
states of plutonium and by difficulties in obtaining groundwaters with different 
compositions.  However, the focus of the study is shifting to synthesis and integration 
of the sorption data to support identification of optimal sorption models that will be 
used in performance assessment.
2.	The biological sorption and transport study (8.3.1.3.4.2) has not been fully 
implemented because of funding priorities.  Since the SCP was issued, study progress 
and developments in the field of subsurface microbiology have been used to change 
the focus of the study.  Changes to the study are discussed in detail in the study plan, 
but no substantive changes to the study have been made since the study plan was 
approved in 1993.  Most of the changes identified in the study plan are simple 
reorganizations of the SCP tasks.  However, one study (v-max and actinide speciation) 
has been deleted because the work was determined to be beyond the needs of the 
program.  Much work remains including support for the development of process 
models for site-scale unsaturated zone transport and waste package degradation, 
site-scale saturated zone transport, and parts of the strategy to protect public health and 
safety after closure of the repository that use container corrosion estimates and 
actinide concentrations.
3.	The development of sorption models study (8.3.1.3.4.3) remains relatively incomplete 
because of resource constraints over the past several years.  The work that has been 
accomplished has generally progressed consistently with the description in the SCP.  
At this time, it appears that it may be necessary to resolve three remaining technical 
questions to produce defensible sorption models for performance assessment.  These 
questions are:
? Oxidation state of plutonium sorbed onto tuffs
? Speciation of neptunium sorbed onto zeolitic tuffs, with emphasis on the roles of 
clinoptilolite and clay
? Speciation of neptunium sorbed onto fracture coatings such as mineral oxides and 
calcite.  The focus of this study has shifted from sorption model development to 
evaluation of the mechanistic sorption models, and identification and selection of 
the optimal sorption model for use in performance assessment.
In addition, recent studies indicate that neptunium and technetium are orders of magnitude less 
soluble under reducing conditions, and that neptunium may coprecipitate with uranium.
1.2.5	Studies to Provide the Information Required on Radionuclide Retardation by 
Precipitation Processes Along Flow Paths to the Accessible Environment 
(SCP Investigation 8.3.1.3.5)
Background and SCP Plans.  The objective of this investigation was to collect data needed to 
evaluate potential radionuclide retardation by precipitation processes.  Data about dissolved 
species concentration limits were intended to provide information on solubility or concentration 
limits for dissolved species of important waste elements under conditions that were characteristic 
of the repository and along flow paths to the accessible environment.  Data about colloid 
behavior would be used to determine the stability of waste element colloids under expected 
site-specific conditions that might be encountered at the repository or along flow paths to the 
accessible environment.  This investigation included two studies developed to accomplish the 
following:
1.	Study 8.3.1.3.5.1 (dissolved species concentration limits):  This study was to:
? Specify the conditions under which solubility experiments would be performed 
and then measure solubilities or concentration limits of important waste elements 
under these conditions
? Identify important aqueous species of waste elements under conditions specified 
and determine the formation constants for those species
? Develop the thermodynamic models and data needed to calculate waste element 
solubilities over a range of conditions expected at the site.
2.	Study 8.3.1.3.5.2 (colloid behavior):  This study was to:
? Determine the formation and stability of waste element colloids, particularly 
plutonium and americium
? Determine the conditions for formation, stability, and break up of colloids, 
including pH, reduction-oxidation state, temperature, and concentration of the 
element
? Determine the effects of these conditions on colloid size, density, composition, 
charge, and chemical reactivity
? Develop models and model parameters to calculate natural colloid concentrations 
and stability and describe the disposition of the waste element species as the 
colloids break up.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The SCP, however, described a more extensive program of data 
collection.  The studies for this investigation have evolved based on technical information 
obtained from laboratory and field studies, model development and data application activities of 
the site characterization program.  Rapidly increasing scientific understanding, along with 
periodic TSPA, have enabled focusing the ongoing site characterization program on the 
remaining uncertainties that are significant to the design, operation and safe performance of the 
potential repository (DOE 1994a).  Reevaluation and prioritization of Project needs has been a 
continuous process based on scientific judgment and resource availability, governed by scientific 
criteria to ensure that data needed for site description, performance assessment, and design 
purposes were collected and analyzed.  Data-collection redundancy and overlap have been 
eliminated.  The data-collection needs have been further analyzed and refined as additional 
knowledge has been gained through years of site characterization activities.  This process has 
resulted in the following changes to the investigation:
1.	The dissolved-species concentration limits study (8.3.1.3.5.1) has been greatly 
reduced.  Emphasis is still focused on identifying the solubility-limiting solids and 
oxidation states and on developing a thermodynamic database for neptunium and 
plutonium.  The strategy for sorption studies and subsequent performance assessments 
generally supported an emphasis on neptunium and plutonium as key radionuclides.  
The interest in investigating oxidation states resulted from the realization that these 
elements are much less soluble under reducing conditions.
2.	In the radiocolloid behavior study (8.3.1.3.5.2), a letter report on plutonium (IV) 
colloids was written to document the literature database (Clark 1994).  Most of the 
planned work on radiocolloids has been deferred.  Uncertainties in radiocolloid 
formation, stability, and mobility will be addressed as part of the AMR process.  
Reasonable ranges in naturally occurring colloid and radiocolloid properties will be 
derived from literature surveys and other direct sources (e.g., Nevada Test Site colloid 
and Argonne National Laboratories spent fuel studies) and indirect sources.
1.2.6	Studies to Provide the Information Required on Radionuclide Retardation by 
Dispersive, Diffusive, and Advective Transport Processes Along Flow Paths to the 
Accessible Environment (SCP Investigation 8.3.1.3.6)
Background and SCP Plans.  The objective of this investigation was to experimentally 
determine the rate of movement and effective retardation of radionuclides by dispersive, 
diffusive, and advective processes.  The dynamic transport column experiments were intended to 
measure the breakthrough or elution curves for tracers through tuff columns.  The diffusion study 
was intended to measure the diffusivity and kinetics of adsorption in a purely diffusive system 
(i.e., no advection) using beakers fabricated from tuff wafers and rock slabs.  This investigation 
included two studies developed to accomplish the following:
1.	Study 8.3.1.3.6.1 (dynamic transport column experiments):  This study was to:
? Measure the rate of movement of radionuclides through crushed tuff columns 
relative to tritiated water and other well-defined chemical species or colloids
? Determine the elution rate of radionuclides as a function of water velocity for 
crushed tuff columns (homogeneous system), for solid rock columns 
(heterogeneous system), and for pure mineral samples
? Measure the relative migration rate of radionuclides through partially unsaturated 
rock columns
? Measure the transport and diffusion of radionuclides through naturally fractured 
tuff
? Quantify the filtration of colloids and particulates by the tuff as a function of 
particle or pore size.
2.	Study 8.3.1.3.6.2 (diffusion):  This study was to:
? Measure the uptake of radionuclides by rock beakers as a function of time
? Measure the diffusion of radionuclides in a purely diffusive system (i.e., no 
advection)
? Determine the distribution of radioactivity in the unsaturated tuff matrix using an 
unsaturated tuff block of the Topopah Spring Tuff or Calico Hills Formation.
Changes and Status.  While there have been no significant changes to the scopes of these 
studies since the SCP (DOE 1988) was issued, these studies have been halted because of revised 
funding priorities.
1.	The dynamic transport column experiments study (8.3.1.3.6.1) is nearly complete.  
Questions remain about the validity of using batch sorption distribution coefficients 
(Kds) for unsaturated zone transport calculations.  These questions need to be resolved 
in FY 2001 to support the unsaturated and saturated zone flow and transport and 
TSPA-SR.  An encouraging, but limited set of data, including data from experiments 
with uranium and selenium, indicate that Kds can be used to make conservative 
predictions of radionuclide transport through unsaturated tuff.
2.	The diffusion study (8.3.1.3.6.2) experiments are nearly complete.  Diffusion 
coefficients have been determined for a fairly comprehensive set of radionuclides, tuff 
types, and water compositions.  Diffusion as a function of saturation in tuffs remains 
to be determined.
1.2.7	Studies to Provide the Information Required on Radionuclide Retardation by All 
Processes Along Flow Paths to the Accessible Environment (SCP 
Investigation 8.3.1.3.7)
Background and SCP Plans.  The objectives of this investigation were to provide a baseline set 
of input data from geochemistry, mineralogy-petrology, hydrology, and other studies needed for 
the integrated radionuclide transport calculations; and outline the strategy that would be used to 
demonstrate the validity of the laboratory-generated geochemical data and the validity of 
transport calculations using that data.  This investigation included two studies developed to 
accomplish the following:
1.	Study 8.3.1.3.7.1 (retardation sensitivity analysis):  This study was to:
? Analyze the processes that may affect transport, including geochemical and 
physical processes, particulate transport, heat-load effects, and coupled 
phenomena
? Develop, using this analysis, laboratory experiments to examine the physical and 
geochemical processes affecting radionuclide transport and other diffusion 
experiments
? Correlate and validate results obtained from laboratory, ESF, and field 
experiments with transport calculations
? Perform calculations of radionuclide transport from the repository to the 
accessible environment using, as a basis, an integrated conceptual 
geochemical-geophysical model of Yucca Mountain
? Verify computer codes and validate the models used in this study to identify 
important contributors to uncertainties in the retardation calculations (sensitivity 
analyses).
2.	Study 8.3.1.3.7.2 (demonstration of the applicability of laboratory data to repository 
transport calculations):  This study was to outline the strategy that would be used to 
demonstrate the validity of the laboratory-generated geochemical data and of transport 
calculations using that data including modeling and a combination of large-scale 
laboratory experiments, field studies, consideration of natural analogs, information 
from processes in the soil zone, and peer review.
Changes and Status.  The primary objectives of this investigation have changed little since the 
SCP (DOE 1988) was issued.  The studies for this investigation have evolved based on technical 
information obtained from laboratory and field studies, model development and data application 
activities of the site characterization program.  Rapidly increasing scientific understanding, along 
with periodic TSPA, have enabled focusing the ongoing site characterization program on the 
remaining uncertainties that are significant to the design, operation and safe performance of the 
potential repository (DOE 1994a).  Reevaluation and prioritization of Project needs 
(DOE 1994a) has been a continuous process based on scientific judgment and resource 
availability, governed by scientific criteria to ensure that data needed for site description, 
performance assessment, and design purposes were collected and analyzed,  Data-collection 
redundancy and overlap have been eliminated.  The data-collection needs have been further 
analyzed and refined as additional knowledge has been gained through years of site 
characterization activities.  This process has resulted in the following changes to the 
investigation.
1.	The retardation sensitivity analysis study (8.3.1.3.7.1) has proceeded generally as 
described in the SCP (DOE 1988).  Some sensitivity analyses that have been 
completed are described in the unsaturated zone and saturated zone transport model 
reports (CRWMS M&O 1997c, pp. 8-1 to 8-57, 9-1 to 9-17, 11-41 to 11-55, 12-23 to 
12-32; CRWMS M&O 1997d, pp. 6-1 to 6-70).  Models assessing the influence of 
waste heat on radionuclide transport have been developed for the unsaturated zone 
(CRWMS M&O 1997c, pp. 11-1 to 11-55) and the saturated zone (CRWMS 
M&O 1997d, pp. 6-51 to 6-55).  The unsaturated zone model is being extended to 
include dual permeability and the coupled effects of chemical reactions such as 
dissolution and precipitation, but the extension is not yet complete.
2.	The study to demonstrate applicability of laboratory data (8.3.1.3.7.2) is being 
developed using hydrologic information from the C-holes.  Another testing complex is 
being planned in the alluvium.  The C-hole tracer tests include a suite of tracers that, 
because of their properties, are helping to quantify fracture flow and adsorption in the 
saturated zone.  The results of the C-hole tests are used to evaluate a variety of models 
ranging from analytical (close-form) solutions to three-dimensional numerical models.  
Evaluation of C-hole data to determine the level of complexity needed in the site-scale 
model is continuing.
3.	Natural analog studies of radionuclide transport in the unsaturated zone were 
conducted under WP 46012122M5 at Pea Blanca, Mexico and at the Idaho National 
Engineering and Environmental Laboratory.  The Pea Blanca study investigated the 
transport history of uranium series radionuclides from a 8 Ma uranium deposit.  The 
Idaho National Engineering and Environmental Laboratory investigations examined 
validity of the dual permeability approach for modeling unsaturated zone flow at the 
Box Canyon location and modeled transport of radionuclides from the Radioactive 
Waste Management Complex.
1.2.8	Studies to Provide the Information Required on Retardation of Gaseous 
Radionuclides Along Flow Paths to the Accessible Environment (SCP 
Investigation 8.3.1.3.8)
Background and SCP Plans.  The purpose of the investigation was to supply input data for 
calculations of gaseous radionuclide transport from the repository to the accessible environment 
at the Yucca Mountain site.  The objectives of this investigation included:  
? Calculating the rates of transport of gaseous radionuclide species between the repository 
and the accessible environment, considering the various driving forces and retardation 
mechanisms that may exist
? Experimentally verifying existing models of gaseous radionuclide transport and 
retardation that were used to assess radionuclide release to the environment.
This investigation included one study developed to accomplish the following:
Study 8.3.1.3.8.1 (gaseous radionuclide transport calculations and measurements):  This study 
was to:
? Determine the manner in which gaseous species were transported in the unsaturated 
zone and calculate transport rates without retardation
? Identify the retardation mechanisms that can affect the transport of gaseous species 
through the unsaturated zone and model these processes so that the effects on transport 
rates can be evaluated
? Measure experimentally gas transport rates under typical unsaturated zone conditions to 
verify calculated models of gas transport and retardation, if they exist.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The SCP, however, described a more extensive program of data 
collection.  The studies for this investigation have evolved based on technical information 
obtained from laboratory and field studies, model development and data application activities of 
the site characterization program.  Rapidly increasing scientific understanding, along with 
periodic TSPA, have enabled focusing the ongoing site characterization program on the 
remaining uncertainties that are significant to the design, operation and safe performance of the 
potential repository (DOE 1994a).  Reevaluation and prioritization of Project needs 
(DOE 1994a) has been a continuous process based on scientific judgment and resource 
availability, governed by scientific criteria to ensure that data needed for site description, 
performance assessment, and design purposes were collected and analyzed.  Data-collection 
redundancy and overlap have been eliminated.  The data-collection needs have been further 
analyzed and refined as additional knowledge has been gained through years of site 
characterization activities.
This investigation was not funded during FY 1997 (see long-range plan/integrated project 
schedule, Yucca Mountain Site Characterization Project Long-Range Plan [CRWMS 
M&O 1996a]).
1.3	ROCK CHARACTERISTICS PROGRAM (SCP SECTION 8.3.1.4)
The rock characteristics program was intended to provide information needed to develop a 
three-dimensional model of the physical properties of the rocks at the Yucca Mountain site.  That 
is, the program would determine the geometries associated with the various material properties 
of the rocks at the site.  The purpose of the three-dimensional model was to provide a 
computer-based representation of the physical properties of the rocks at the site.  The model was 
intended to include data defining the distribution of parameters (physical properties) within 
specified property-dependent units.  The model data were also intended to provide input for 
numerical computer analyses that involve hydrologic, thermal, thermomechanical, and 
geochemical processes.
The three-dimensional physical properties model was intended to be a representation of the 
Yucca Mountain repository site containing various kinds of data on assorted geologic, 
geohydrologic, thermal, mechanical, and geochemical properties.  One of the purposes of the 
model was to allow predictions of how a physical property changes spatially within and across 
the boundaries of the model.  The relevant model boundaries would represent distinct changes in 
the property of interest.
The investigations included in the rock characteristics program are summarized in the following 
sections.
1.3.1	Development of an Integrated Drilling Program and Integration of Geophysical 
Activities (SCP Investigation 8.3.1.4.1)
Background and SCP Plans.  The objective of this investigation was to provide a mechanism 
for the overall integration of the surface-based activities to be conducted during site 
characterization.  The SCP (DOE 1988, Section 8.3.1.4.3.1) and early study plan drilling 
programs provided for drilling the following holes:
? 12 systematic drilling program boreholes supporting the rock properties investigations
? 25 additional unsaturated zone neutron access boreholes for study of shallow 
infiltration in the site area
? 17 new unsaturated zone boreholes supporting characterization of the deeper part of the 
unsaturated zone
? At least 5 deep water table holes, and a southern tracer complex of 3 boreholes to test 
the saturated zone
? 3 volcanic boreholes
? 3 additional deep geologic boreholes.
The geophysical integration activity was intended to review and evaluate planned geophysical 
surveys for:
? Consistency with the results from past surveys
? Direct or supportive uses of the data for licensing
? The likelihood that useful data would be generated
? The need for the planned effort with respect to alternate methods for obtaining the data
? Scheduling with respect to other studies and the overall priorities for site 
characterization.
1.	Activity 8.3.1.4.1.1 (development of an integrated drilling program):  This activity was 
to:
? Ensure data collected during surface-based testing activities were representative 
of phenomena and structural characteristics
? Integrate and prioritize surface-based activities
? Maintain a system of technical element baseline approval and control.
2.	Activity 8.3.1.4.1.2 (integration of geophysical activities):  This activity was to 
provide a mechanism for information exchange, data analysis, and overview of 
planned geophysical site characterization activities.
Changes and Status.  At the DOE-NRC Technical Exchange in April 1995, a list of 
35 boreholes was presented to the NRC as examples of the Program Plan of December 1994.  
The list was generally consistent with plans outlined in the SCP (DOE 1988) and early study 
plans, as described above.  Of the holes on this list, three boreholes have been drilled since 1995, 
and three other listed holes plus one new borehole are included in the current long-range plan.  
However, the remaining 29 listed boreholes identified are unlikely to be drilled.  Currently, two 
surface boreholes associated with the East-West Cross Drift program are complete.  Borehole 
USW SD-6 has been drilled to a depth of 2,808 ft (855.9 m), and rock properties tests are under 
way for the TSw2 repository horizon.  Borehole USW WT-24, for testing the large hydraulic 
gradient, has been completed at a depth of 2834 feet (864 m), and core samples have been 
collected for rock properties tests.  For additional information about borehole USW WT-24, see 
the description in the Changes and Status section for Study 8.3.1.2.3.1.  As noted below, 
supplemental data have been developed from other sources.
1.	For the integrated drilling program (8.3.1.4.1.1), although the plans for additional 
boreholes have been reduced compared with the plans described in the SCP 
(DOE 1988), 11 additional north ramp geologic boreholes were drilled in support of 
ESF design.  Two of these boreholes supplemented SCP drilling and provided core 
from the potential repository horizon that originally was to be provided by the 
proposed (and subsequently canceled) systematic drilling and unsaturated zone 
boreholes.  While the lack of additional boreholes may reduce confidence in process 
models, data from the revised drilling program is sufficient for purposes of the 
Viability Assessment.  Although the surface based program was less than originally 
planned, a large amount of drilling was completed in the ESF and East-West Cross 
Drift.  Systematic drilling was conducted throughout the East-West Cross Drift from 
the entrance to the terminal end.  A series of short boreholes were drilled every 50 m 
for the entire 2,800 m of excavation.  In addition, boreholes were drilled into the invert 
of the East-West Cross Drift as well as two locations in the ESF in order to determine 
the depth that water had traveled during construction activities.  An accelerated 
drilling and testing program was conducted at the Busted Butte unsaturated zone test 
area.  Boreholes were installed to provide a means to characterize the rock type, and 
then the boreholes were used as injection and collection locations for the testing 
activities.  The Fran Ridge Large Block Test was drilled for post-test characterization 
of the block.  These drilling activities have provided needed information specific to the 
bedded tuffs and the welded units directly associated with the repository horizon.
	During FY 1999, drilling activities were aggressive at the Nye County EWDP and 
USW SD-6, and in the ESF and East-West Cross Drift.  The Project gained valuable 
information from the Nye County EWDP, including lithology, water level data, 
hydraulic test results, alluvium sorption measurements, hydrochemistry data, and 
Eh/pH data that have been incorporated into the DOE models of the saturated zone.  
Information gained from the post-test characterization of the Fran Ridge Large Block 
drilling activities and the chlorine-36 validation boreholes in the ESF are expected to 
provide insights into locations of potential fast pathways for water movement.
	During FY 2000 and FY 2001:
	?	The chlorine-36 bomb-pulse validation study, which utilizes 50 short boreholes 
associated with two identified faults located in the ESF, continued.
	?	Niche and alcove construction and geologic mapping in the ESF main drift and 
cross drift have added substantial data to the structural and stratigraphic 
databases, particularly for the potential repository horizon.
	?	Most of the boreholes planned as part of the Nye County EWDP were completed 
and have provided information specific to the alluvial section down through the 
carbonate level.
	?	Samples were collected for use by the Project and Nye County researchers.
2.	In the study to integrate geophysical activities (8.3.1.4.1.2), a comprehensive 
geophysical testing program (regional- and repository-scale, surface and subsurface, 
ground-based and aerial surveys) was conducted.  Since 1991, 40 boreholes have been 
cored at Yucca Mountain, and 24 new and existing boreholes were logged (under 
subcontracts to private sector geophysical corporations) with industry-standard 
wireline geophysical tools.  To date, 20 of the post-1991 boreholes have been logged, 
and 4 pre-1991 boreholes have been re-logged with modern wireline geophysical 
tools.
	Nearly 23 miles of deep regional seismic reflection profiling, 35 miles of 
high-resolution shallow seismic reflection profiling in the repository area, and 
coincident magnetic and gravity profile data have been collected.  The aeromagnetic 
and ground gravity regional potential field data sets have been synthesized, and final 
interpretations and subsurface structural models are being generated by further 
analysis and to support the tectonics, volcanism, and hydrologic investigations.  
Follow-up documentation for many of the geophysical activities and proposed testing 
programs were presented in the 1990 and 1995 Geophysics White Papers (YMP 1990; 
Oliver et al. 1995).  Most of the standard and prototype testing programs outlined in 
YMP (1990) were conducted during the past five years.  Enhancements to the 1990 
proposals included completion of vertical seismic profiling investigations to repository 
depths in three boreholes near the potential repository.  These investigations are 
summarized in Majer et al. (1996) and Brocher et al. (1996, p. 1-2).
1.3.2	Geologic Framework of the Yucca Mountain Site (SCP Investigation 8.3.1.4.2)
Background and SCP Plans.  The three objectives of this investigation generally covered those 
studies and activities that would further allow an understanding of the large-scale variations in 
stratigraphy and structure needed to support design and performance assessment calculations.  
First, this investigation was to provide primary data on the lateral and vertical variations in site 
stratigraphy through acquisition of borehole cores and cuttings and from surface geologic 
mapping.  Second, the investigation was to provide information that would allow 
three-dimensional modeling (through the use of borehole and surface geophysical surveys) of the 
variations in properties of interest between points of primary data.  Third, information was to be 
provided on the lateral and vertical variations of structural elements that may affect in situ 
properties of interest (e.g., fracture-related flow) in conjunction with site characterization 
investigations on geohydrology, geochemistry, postclosure tectonics, and seismicity 
(i.e., preclosure tectonics).  This investigation included three studies developed to accomplish the 
following:
1.	Study 8.3.1.4.2.1 (characterization of the vertical and lateral distribution of 
stratigraphic units within the site area):  This study was to:
? Determine the vertical and lateral variability, emplacement history, and 
characteristics of stratigraphic units and lithostratigraphic subunits within the 
Paintbrush Group, tuffaceous beds of Calico Hills Formation, Crater Flat Group, 
and possibly older volcanic rocks
? Improve confidence in stratigraphic models by drilling three additional deep 
geologic boreholes and by incorporating results from surface-based and borehole 
geophysical surveys and petrophysical properties testing
? Determine the distribution of rock properties within lithostratigraphic units
? Provide magnetic-property data to help interpret volcanic stratigraphy and 
structure and to assess the rotation of rock units in relation to the geologic 
structures
? Integrate geophysical activities.
2.	Study 8.3.1.4.2.2 (characterization of the structural features within the site area):  This 
study was to:
? Determine the frequency, distribution, characteristics, and relative chronology of 
structural features within the Yucca Mountain site area
? Extend the 1:12,000 scale mapping of zonal features and variations in exposed 
tuffs of the Paintbrush Group in the site area to help identify structural 
displacements of 10 m or less and to detect subtle changes in structural styles
? Conduct surface-fracture network studies to provide measurements and analyses 
for hydrologic flow path modeling of the unsaturated zone and to help develop 
tectonic models and determine mechanical response of fractured rock to 
excavation and thermal loading
? Conduct borehole evaluations of faults and fractures to assess reliability and 
usefulness of borehole techniques, determine vertical and lateral variability and 
characteristics of subsurface fractures, and identify subsurface characteristics of 
fault zones
? Conduct geologic mapping of the ESF to determine vertical and horizontal 
variability of fracture networks and lithostratigraphic features, characterize major 
faults and fault zones, and assist in evaluation of test locations
? Conduct seismic tomography and vertical seismic profiling to detect and 
characterize subsurface fracture networks by extrapolating the relation between 
seismic-propagation characteristics and observed fracture patterns to unexplored 
volumes of rock.
3.	Study 8.3.1.4.2.3 (three-dimensional geologic model):  This study was to develop a 
three-dimensional geologic model of the site area that incorporates stratigraphic, 
structural, geophysical, and rock properties information pertinent to site 
characterization, design, and performance assessment activities.
Changes and Status.  The objectives of the investigation remain the same as defined in the SCP 
(DOE 1988).  The scope of the investigation has, for the most part, followed that described in the 
SCP, and in some instances has exceeded that scope.  The notable exception is the decision not 
to drill the additional geologic holes.  Overall, the purpose of the investigation has been fulfilled, 
resulting in the collection of information sufficient to achieve the original objectives of each 
study as presented in the SCP.  Changes that have occurred in the investigation are summarized 
below:
1.	In the distribution of stratigraphic units study (8.3.1.4.2.1), the drilling of three deep 
geologic holes proposed in the SCP (DOE 1988) has not occurred.  These holes were 
intended to investigate lithostratigraphic and structural conditions associated with the 
large hydraulic gradient in the saturated zone just north of the site area in Yucca Wash, 
to provide data on the thickness of key lithostratigraphic units in the vicinity of Windy 
Wash, and to provide data on the thickness of the Paintbrush Group southwest of 
Busted Butte.  The three geologic holes were to be targeted at the corners of the site 
area and serve as control points for geologic modeling and interpretations of 
seismic-reflection profiles.  Although the Project has completed an important set of 
boreholes not anticipated by the SCP (eleven north ramp geologic boreholes), and 
successfully implemented an extensive surface and borehole geophysical studies 
program, additional work may be needed to determine the depth to the top of the 
Paleozoic rocks and the configuration of the Tertiary-Paleozoic contact underlying 
Yucca Mountain; and stratigraphic and structural controls on the large hydraulic 
gradient north of the site.  These features have potentially important implications for 
flow of water under the repository area in the saturated zone and the possible 
migration of radionuclides away from the potential repository.  For the 
Tertiary-Paleozoic contact, the uncertainty in configuration results in a range of 
possibilities regarding the relative volumes of Tertiary volcanic tuffs and Paleozoic 
sedimentary rocks in the saturated zone through which water that potentially could 
carry radionuclides, would pass on its route from the repository to the accessible 
environment.  Because the Tertiary and Paleozoic rocks have significantly different 
hydrologic and geochemical properties, their presence or absence affects flow paths, 
velocities, dilution, and sorption.  Similarly, for the large hydraulic gradient, the 
uncertainty results in estimates of saturated zone flux, flow velocities, and dilution 
beneath the site that likely will differ considerably for different explanations of the 
cause of the large hydraulic gradient (Luckey 1996, p. 2).  The possible effects on 
repository performance predictions of the uncertainty associated with these two 
features were considered under the alternative conceptual models issue at the 
Saturated Zone Flow and Transport Model Abstraction and Testing Workshop held 
April 1-3, 1997 in Denver, Colorado (CRWMS M&O 1997a).  Alternative 
representations of the large hydraulic gradient were not addressed by the workshop 
because it was the consensus of participants that these alternative representations 
would have little or no impact on the predicted concentrations of radionuclides 30 km 
down-gradient from the potential repository (CRWMS M&O 1997a, p. 1-12).  
Alternative configurations for the Tertiary-Paleozoic contact underlying Yucca 
Mountain also were not considered by the workshop participants because the 
alternative representations were presumed to have little or no impact on predicted 
concentrations of radionuclides 30 km down-gradient of the potential repository.
	Current work that was originally planned to evaluate the large hydraulic gradient and 
program changes are described in Sections 1.1.1 and 1.1.3 of this report.  Additional 
work to interpret vertical seismic profile data from borehole UE-25 P#1 was 
conducted during FY 1998 (Feighner et al. 1998, p. 1) to provide additional 
information about the Tertiary-Paleozoic contact.
	The SCP (DOE 1988) scope has been exceeded in the measurement and verification of 
stratigraphic sections, revision of the stratigraphic nomenclature, and development of a 
detailed microstratigraphy for characterization of features observed in core holes.  In 
addition, although not all the areas and features targeted in the SCP were covered, an 
extensive surface-based geophysical-survey program has been completed, including 
nearly 23 miles of deep regional seismic-reflection profiling, 35 miles of shallow 
high-resolution seismic-reflection profiling in the site area, and coincident magnetic 
and gravity surveys of the site area.  The integration of geophysical activities was 
deleted from this study, as proposed in draft Revision 7 of the Site Characterization 
Program Baseline, because the integration is being performed under Investigation 
[Study] 8.3.1.4.1.2 (Crawley 1992).  Note that DOE directed that Revision 7 be 
withdrawn and resubmitted, but that the resubmitted Revision 7 contains the work 
scope revisions described.
2.	In the structural features study (8.3.1.4.2.2), deficiencies in available surface geologic 
maps and changes in criteria for stratigraphic units have resulted in an intensive 
program to remap and to evaluate existing 1:12,000-scale maps of the site area (Study 
Plan 8.3.1.4.2.2, Revision 2; Progress Reports #6 through #10, Section 2.2.3.4, 
DOE 1992a; 1992b; 1993; 1994b; and 1994c; Progress Reports #11 through #15, 
Section 3.3.4, DOE 1995a; 1995b; 1996b; 1996c; and 1997b).  Emphasis in the 
remapping effort was placed on the central block area of Yucca Mountain (Day, Potter 
et al. 1998).  Geologic mapping at a scale of 1:6,000 has been conducted in an area 
extending from Comb Peak in the north to Busted Butte in the south, and from Jet 
Ridge on the west to Midway Valley on the east (see Progress Reports #6 through 
#15).  Although 1:12,000-scale geologic mapping of zonal features was not extended 
southward to U.S. Highway 95 as originally planned (DOE 1988, p. 8.3.1.4-67; 
Progress Reports #6 through #15), detailed 1:6,000-scale mapping was extended 
northeast of Yucca Wash in the Paintbrush Canyon area to include several faults that 
affect the repository-area structure, and to elucidate important stratigraphic-facies 
issues (Dickerson and Drake 1998).  A 1:24,000 scale geologic map of the 
Yucca Mountain area also was completed (Day, Dickerson et al. 1998) and extends 
from the Prow in the north to Busted Butte in the south, and from Windy Wash in the 
west to Fortymile Wash in the east.  Originally, new geologic mapping and remapping 
was not extended south of Busted Butte because that is the southern limit of both the 
site-area geologic framework model and site-scale unsaturated zone flow model.  
However, recent emphasis on the saturated zone down-gradient from Yucca Mountain 
resulted in an initiative to produce an updated geologic map of the area of the site 
saturated zone flow model.  Consequently, in FY 1998, work began on a preliminary 
1:50,000-scale geologic map to support saturated zone model activities for TSPA-VA 
and TSPA-LA and to provide deep structural geologic framework support for the 
saturated zone site model.  During FY 1999, the map for the site-scale saturated-zone 
flow model area was completed, and was technically reviewed and submitted for 
publication.  Preliminary digital versions of the map and cross sections were 
transmitted to the site-scale saturated-zone modeling group to support timely 
completion of the modeling activities.  The map extends from upper Beatty Wash in 
the north to 5 miles south of U.S. Highway 95 in the south, and from Bare Mountain in 
the west to Little Skull Mountain in the east.  Cross-sectional interpretations 
accompanying the map show enough of the Paleozoic rocks to allow the various thrust 
sheets to be distinguished.  In FY 2001, the geologic map for the site-scale saturated 
zone flow model was approved and published (Potter et al., in progress).
	Several pavement studies and detailed surface-mapping exercises have generated a 
wealth of fracture data for the development of site-area fracture models (Sweetkind 
and Williams-Stroud 1996, p. 11).  With reconfiguration of the ESF from vertical 
shafts to ramps and alcoves, the strategy and methods for mapping fracture networks, 
faults, and lithostratigraphic features have changed considerably (see Study 
Plan 8.3.1.4.2.2, Revision 2).  The most notable of these changes has been the 
acquisition of a large volume of data collected through detailed line surveys and full 
periphery mapping of the ESF.
	Although vertical seismic profiling has been completed to repository depths in 
10 available boreholes near the potential repository, the scope and strategy for vertical 
seismic profiling have changed significantly.  Initial plans were to test this method in 
borehole USW G-4 (for vertical seismic profiling) and in the C-holes for the 
cross-hole tomographic imaging.  USW G-4 was selected because of its proximity to 
the planned vertical shaft of the Exploratory Shaft Facility.  When the Exploratory 
Shaft Facility configuration was modified to ramps and drifts, testing in USW G-4 
became less important.  Consequently, multi-offset vertical seismic profiling using 
P- and S-waves was first used in USW NRG-6, a borehole close to the ESF north 
ramp, and in USW WT-2, a borehole close to the Ghost Dance fault (Progress 
Reports #8 through #10 (DOE 1993, 1994b; 1994c), Section 2.2.3.4; Progress 
Report #11 (DOE 1995a), Section 3.3.4).  Both surveys met the objectives of the study 
plan, because fracture and fault characteristics were interpreted from the data.  
Subsequent vertical seismic profiling surveys in additional holes (USW G-2, 
USW G-4, USW SD-12, UE-25 RF#7a and UE-25 RF#4) were performed using 
P- and S-wave sources for defining shallow S-wave structure for input to site 
seismic-response models (Progress Report #13 (DOE 1996b), Section 3.3.4).
	In addition, vertical seismic profiling data were collected in a state-of-the-art testing 
program in borehole UE-25 UZ#16 (Progress Reports #13 through #15 (DOE 1996b; 
1996c; 1997b), Section 3.1.7); data from this investigation are being interpreted.  
Tomographic studies will not be done in UE-25 UZ#16 because drilling of the 
additional, closely spaced boreholes at the UE-25 UZ#16 site, which would have 
supported gas-phase investigations, has been deleted from the long-range plan 
(CRWMS M&O 1996a, p. A-6).  The tomographic studies were intended to 
extrapolate observations of structural features and fracture content between surface 
exposures, underground tunnels and drifts, and boreholes (see Study Plan 8.3.1.4.2.2, 
Revision 2).  However, the development of the detailed system for identifying 
lithostratigraphic units (Buesch, Spengler et al. 1996a) and the three-dimensional 
geologic model (Buesch, Nelson et al. 1996; CRWMS M&O 1997e) has obviated the 
need for tomographic studies in most Project applications.  This is because the detailed 
system of lithostratigraphic descriptions, which is based on crystal content, phenocryst 
assemblage, depositional texture, degree of welding, high-temperature crystallization, 
precipitation from the high-temperature vapor phase, and fracture characteristics, 
makes it possible to correlate the lithostratigraphic units and properties through 
regions of sparse data (Buesch, Spengler et al. 1996b).  Nevertheless, during FY 1998 
some surface-to-ESF seismic tomography was performed.  A surface-to-ESF seismic 
tomography study examined the interval between the surface and the repository 
horizon, and the unpublished data and interpretations are available (Majer 1999).
	Cross-hole tomographic imaging in the C-holes was completed as planned.  
No additional tomographic work is planned at other locations in the vicinity of Yucca 
Mountain because of the lack of available closely spaced boreholes that penetrate 
sufficient intervals in the saturated zone.  (The length of the holes beneath the water

	table must be at least twice the hole separation.)  Available seismic sources will not 
operate in dry holes and give the required data quality.
3.	In the three-dimensional geologic-model study (8.3.1.4.2.3), the SCP (DOE 1988) 
strategy has evolved considerably.  Whereas the original three-dimensional geologic 
model was envisioned to be primarily conceptual and to encompass a series of 
isopach and structure contour maps, correlation diagrams, and cross sections, the 
present model is a fully three-dimensional, computer-based stratigraphic, structural, 
and properties model (see Section 3.3.5 of Progress Report #16 (DOE 1997a) and 
Section 5.5 of Progress Report #17 (DOE 1998b)).  Presently, the integrated site 
model includes a geometric representation of selected rock units and structures 
(the geologic framework model) and a set of rock-properties models and data sets 
(CRWMS M&O 1997e).  The geologic framework model encompasses a 166 km2 
rectangular area around the Controlled Area Boundary (CRWMS M&O 1997e; 
Rautman et al. 1986) and includes more than 30 lithostratigraphic layers between the 
land surface and the top of the Paleozoic rocks as described by Majer et al. (1996).  
The 43 faults included in the three-dimensional model (Version ISM3.1) are those 
that:
? Lie outside the repository area, are longer than 2 miles (3.2 km), and have offsets 
greater than 100 ft (30 m)
? Lie inside the repository area, are longer than one mile (1.6 km), or have offsets 
greater than 100 feet (30 m)
? Their exclusion would produce a mismatch between the model and mapped 
outcrop patterns (see CRWMS M&O 1997e, p. 22 for additional information).
	Rock properties in the integrated site model include matrix porosity, bulk lithophysal 
porosity, saturated hydraulic conductivity, density, thermal conductivity, mineralogy, 
and apparent ages and isotopic ratios for the Topopah Spring Tuff welded interval at 
the repository horizon.  In FY 2000, a comprehensive report on the three-dimensional 
geologic model was completed (CRWMS M&O 2000ah).
1.3.3	Development of Three-Dimensional Models of Rock Characteristics at the 
Repository Site (SCP Investigation 8.3.1.4.3)
Background and SCP Plans.  The purpose of this investigation was to synthesize and integrate 
information collected from various laboratory and field investigations into comprehensive 
three-dimensional, computer-based models of rock characteristics.  The studies were intended to 
document vertical and lateral variations in rock properties, to provide information and statistical 
testing necessary to permit modeling of properties between control points, and to characterize 
key rock property variations in the site area.  The investigation provides a variety of work 
products, such as geologic maps and cross sections, to design and performance assessment 
groups.  These work products typically depict variations in physical properties such as rock 
compressive strength, thermal conductivity, gas permeability, and fracture density

The SCP (DOE 1988) and derivative study plans specified that the majority of data for this 
investigation would be obtained from 7 to 12 systematic drilling boreholes to be drilled in the 
repository area, and from unsaturated zone boreholes located along the perimeter of the potential 
repository area.  Additional data for the rock properties modeling investigation were to be 
provided by various unsaturated zone boreholes.
The objectives of this investigation were to characterize the three-dimensional distribution of 
rock characteristics, and hydrologic and geochemical variables, for the unsaturated zone at 
Yucca Mountain; integrate quantitative and semiquantitative data on rock characteristics; and 
apply the results.
1.	Study 8.3.1.4.3.1 (systematic acquisition of site-specific subsurface information):  This 
study was to acquire rock samples, analytical data, and basic descriptions of the 
subsurface geology of the repository site on a systematic basis.
2.	Study 8.3.1.4.3.2 (three-dimensional rock characteristics models):  This study was to 
develop computer-based three-dimensional models that integrate quantitative and 
semiquantitative data on rock characteristics in light of constraining information 
developed by studies of the geologic framework of the Yucca Mountain site 
(Investigation 8.3.1.4.2).
Changes and Status.  The primary objectives of the investigation remain the same, with minor 
modifications, as those identified in the SCP (DOE 1988).  The objectives include acquiring rock 
samples and determining physical properties, presenting the analytical data, providing a basic 
description of subsurface rock characteristics derived from systematic drilling and unsaturated 
zone boreholes, and presenting rock properties variations as three-dimensional computer-based 
numerical models.  The investigation objectives require a broad scope of activities.  One major 
enhancement to the SCP program was the amplification of the responsibilities for integration of 
results from Investigation 8.3.1.15.1 (thermal and mechanical rock properties), which was an 
aspect of the investigation never clearly identified in the SCP.  Also, minor task adjustments 
moved the majority of stratigraphy and structural synthesis and associated model development to 
Investigation 8.3.1.4.2 (Geologic Framework of Yucca Mountain).
1.	In the study to systematically acquire site-specific subsurface information 
(8.3.1.4.3.1), the FY 1995 Program Plan (DOE 1996a, pp. 4655) presented proposals 
to drill 12 systematic drilling boreholes and reduced the number of planned 
unsaturated zone holes to 14.  Six of the 12 systematic drilling boreholes were planned 
to support the license application.  Four systematic drilling holes have been completed.  
The range of spatial correlation for at least one material property of interest, porosity, 
now appears to be greater than originally thought (Rautman and McKenna 1997, 
Tables 12 through 16; Rautman 1991, Table 4; Istok et al. 1994, pp. 755758; 
McKenna and Rautman 1995, Tables 11 through 15).  Hence, the results of modeling 
porosity are more reliable than would have been expected had the correlation been 
less.  The number of systematic drilling boreholes eventually drilled may exceed 
four, depending on the results of characterization and modeling of rock properties and 
as-built design information obtained from ESF construction.  In FY 1999, a fifth 
systematic drilling borehole (USW SD-6) was drilled at the crest of Yucca Mountain 
as part of the initiative for enhanced characterization of the repository block.  The 
borehole was drilled to a total depth of 2,808 feet (855.8 m), ending in the Bullfrog 
Tuff of the Crater Flat Group (DOE 2000, Section 3.4).
	Outside the scope of the SCP investigation, Nye County officials are also recording 
fluid pressure data in boreholes UE-25 NRG#4 and UE-25 ONC#1 supporting 
long-term and short-term monitoring of drilling and excavation effects on the ambient 
pressure and thermal system within Yucca Mountain (i.e., changes in ambient 
conditions induced by the effects of perturbation of the ambient system by the tunnel 
boring machine have been documented).  Larger-scale bulk properties, notably bulk 
density, are being estimated using sensor responses in these boreholes, and these 
estimates will provide a level of support to the thermal design process that was not 
anticipated in the SCP (DOE 1988).
2.	In the study to develop three-dimensional rock characteristics models (8.3.1.4.3.2), 
plans were to complete assessment of rock properties data derived from borehole and 
ESF samples, to prepare models of the various rock properties, and to provide rock 
properties models to various performance assessment activities.  The Rock Properties 
Model (RPM3.1) Analysis Model Report (CRWMS M&O 1999h) has been completed 
and supports the Integrated Site Model Process Model Report (CRWMS M&O 
2000ah) and TSPA-SR.  Information needs identified during development of these 
models will be used to evaluate the need to drill additional systematic drilling 
boreholes.
1.4	CLIMATE PROGRAM (SCP SECTION 8.3.1.5)
Evaluation of the available data on recent climate, meteorology, and paleoclimate indicated that 
more data were required than were available on the paleohydrology, paleoclimate, and modern 
climate of the Yucca Mountain area to adequately predict future climate and its possible effects 
on site hydrology relative to repository performance.  The SCP climate program (DOE 1988) 
was developed to provide data on past, present, and possible future climate conditions and to 
determine the effects of climate change on surface, unsaturated zone, and saturated zone 
hydrology.  Specifically, the effects of future climate on geohydrology were to be determined to 
provide input to performance assessment and design.
The investigations included in the climate program are summarized in the following sections.
1.4.1	Studies to Provide the Information Required on Nature and Rates of Change in 
Climatic Conditions to Predict Future Climates (SCP Investigation 8.3.1.5.1)
Background and SCP Plans.  The objective of this investigation was to provide recent 
meteorological data and Great Basin historical climate data for use in calibrating (using present 
conditions) and validating (using past conditions) models of future climate.  
A paleoclimate-paleoenvironment synthesis was to be developed from data from studies of lake, 
playa, and marsh sediments, packrat (Neotoma sp.) middens, vegetation calibrations, and soil and 
surficial deposits.  This synthesis was to provide time-sequential reconstructions for the 
modeling activities as well as for Investigation 8.3.1.5.2.  These models were to attempt to 
estimate climatic variables for the next 100,000 years to forecast future climatic conditions.  This 
investigation included six studies developed to accomplish the following:
1.	Study 8.3.1.5.1.1 (characterization of modern regional climate):  This study was to:
? Characterize modern regional climate to provide a baseline for the interpretation 
of climatic variation
? Characterize synoptic climate to determine modern spatial and temporal 
variations in precipitation, air temperature, cloud cover, and other meteorological 
variables
? Develop modern vegetation-climate calibration relationships, assess lake-climate 
relationships, and develop and test climate-circulation models to specify 
relationships between global-scale circulation patterns and the regional and local 
climate features of relevance to site performance
? Determine the climate conditions (i.e., time, temperature, seasonality, and air 
masses) under which recharge occurs.
2.	Study 8.3.1.5.1.2 (paleoclimate study:  lake, playa, and marsh deposits):  This study 
was to:
? Establish the nature, timing, duration, and amplitude of paleoclimate changes 
based on analyses of paleontologic, geochemical, and stratigraphic-
sedimentologic data obtained from lacustrine sediments in or near southern 
Nevada
? Assemble and interpret, in paleoclimatic terms, detailed records of ostracodes, 
diatoms, and pollen, and other types of fossils to identify, enumerate, and interpret 
paleontologic data that emphasize the past 50,000 years in great detail, the past 
200,000 years in moderate detail, and the past 1,000,000 years in some detail
? Identify and characterize the general physical and chemical properties of 
sedimentary units from outcrops, shore deposits, and cores to determine their 
physical and relative temporal framework
? Analyze the chemical and mineralogic characteristics of sediments to determine 
the chemistry of the water from which the minerals precipitated and to determine 
sediment provenance
? Determine the specific environment of deposition for the sedimentary units
? Obtain an accurate, precise chronologic framework of the lake, playa, and marsh 
deposits sampled in this study.
3.	Study 8.3.1.5.1.3 (climatic implications of terrestrial paleoecology):  This study was 
to:
? Provide quantitative estimates of changes in climatic variables (e.g., precipitation 
and temperature) for the southern Great Basin
? Determine the nature, timing, duration, and magnitude of past vegetation change 
as recorded in plant macrofossil assemblages preserved in ancient packrat (Neotoma 
sp.) middens for the last 50,000 years and in the stratigraphic record of fossil pollen 
grains for the last 150,000 years
? Translate the vegetational records provided by packrat midden and palynological 
investigations and available dendroclimatological data into quantitative estimates 
of past climatic variables.
4.	Study 8.3.1.5.1.4 (paleoenvironmental history of the Yucca Mountain region):  This 
study was to:
? Evaluate the paleoenvironmental record at Yucca Mountain and surroundings in 
light of the inferred paleoclimate history of the southern Great Basin to 
distinguish between effects of climate-related surficial processes from those 
produced by tectonic activity
? Conduct soil-properties modeling studies to determine the relations among late 
Holocene soils and modern climatic parameters, analyze properties of soils at 
Pahute Mesa and near Tonopah as analogs to soil formation at Yucca Mountain 
during pluvial conditions, compare properties of early Holocene and Pleistocene 
soils to paleoclimatic models that were reconstructed from other lines of evidence, 
frame climatic scenarios as a function of the depth, distribution, and quantity of 
pedogenic carbonate and other soil parameters, and to quantify rates of soil 
development in specific climates for use as a dating tool for Quaternary deposits 
and ages of fault movements
? Conduct detailed mapping of surficial deposits in the vicinity of Yucca Mountain 
to support climate, geomorphic, tectonic, infiltration, engineering, and facilities 
studies
? Determine the distribution of major concentrations of calcite-silica vein deposits 
at or near the ground surface at Yucca Mountain
? Document eolian erosion and deposition in the Yucca Mountain area during the 
last 750,000 years and the associated paleoenvironmental conditions.
5.	Study 8.3.1.5.1.5 (paleoclimate-paleoenvironmental synthesis):  This study was to 
conduct a paleoclimate-paleoenvironmental synthesis by comparing paleoclimatic 
estimates from various proxy data sets and providing summaries of paleoclimatic data 
in formats required for future climate and paleohydrology investigations.
6.	Study 8.3.1.5.1.6 (characterization of future regional climate and environments):  This 
study was to:
? Estimate values for regional climatic parameters for the Yucca Mountain area 
over the next 100,000 years, with special emphasis on the next 10,000 years, and 
provide estimates of future precipitation, temperature, and evapotranspiration for 
input to hydrologic models
? Identify and estimate factors controlling global climate over the next 
100,000 years, including the extent and climatic effects of ice sheets
? Provide boundary conditions for regional climate models through the use of 
general-circulation models
? Establish the feasibility of using a regional-scale numerical climate model for 
predicting future climatic conditions at Yucca Mountain and calibrate the model 
against modern climatic data and validate it with paleoclimatic data
? Conduct linked global-regional climate modeling to formulate scenarios of future 
climate in the Yucca Mountain area over the next 100,000 years and to determine 
the associated meteorological parameters for input to hydrologic and erosion 
models
? Conduct empirical climate modeling to formulate scenarios of future climate in 
the Yucca Mountain area over the next 100,000 years and to determine the 
associated meteorological parameters for input to hydrologic and erosion models.
Changes and Status.  The objectives of the paleoclimate work have not changed significantly 
since the SCP (DOE 1988) was issued and studies have been conducted mostly as described in 
the SCP.  These studies remain the foundation of the climate program and provide the basis to 
estimate bounds on future climatic conditions.  Data from different sample suites have been used 
to develop numerical transfer functions for using these data sets to quantitatively estimate past 
climatic parameters such as precipitation and temperature.  Collection of data from different 
sample media has provided independent lines of evidence and data from one sample suite to 
corroborate data from another sample suite.  The data sources are sufficiently extensive that data 
synthesis has provided a robust basis for describing past and current climatic conditions for 
modeling purposes.  Ultimately, the future climate studies may use linked model output as 
numerical input for hydrologic process models.  Testing activities described in the SCP for this 
investigation are near completion.  Changes that have occurred in the investigation are 
summarized below:
1.	In the study of modern regional climate (8.3.1.5.1.1), the scope has been limited to 
determining stable and radiogenic isotopes in samples of modern precipitation to 
establish baseline data against which to compare the isotopic content of lake, playa, 
marsh, and paleospring deposits (see Study Plan 8.3.1.5.1.1, p. 1-1).  Samples of 
precipitation were collected in the vicinity of Yucca Mountain for 2.5 years and 
analyzed to determine the relationships among isotopic composition, season and 
magnitude of precipitation events, and topographic elevation (Progress Report #13, 
Section 3.4.1, p. 3-112 (DOE 1996b)).  Meteorological and other climatic data 
necessary for characterization of modern regional climate have been collected and 
analyzed in Study 8.3.1.2.1.1 in the geohydrology program and in Investigation 
8.3.1.12.1 in the meteorology program.
2.	In the study of the paleoclimate of lake, playa, and marsh deposits (8.3.1.5.1.2), efforts 
have focused on obtaining relevant data sets in all study areas (recent meteorological, 
aquatic, terrestrial, and surficial) and correlating these data with orbital parameters to 
produce a time-sequential reconstruction.  Multiple cores and deposits from relevant 
lake basins and spring deposits are being used to extract ostracode, diatom, and pollen 
data sets.  A significant difference between the current study and that outlined in the 
SCP (DOE 1988) is the period of time selected for the most detailed paleoclimate 
characterization.  The study focused most intensively on the last 400,000 years 
because this time frame represents a full climate cycle consisting of four 100,000-year 
subcycles, each containing a glacial-interglacial couplet.  More importantly, 
interpretation of the relationship between climate change and insolation, which is 
determined by the earths orbital properties, indicates the climatic conditions during 
the next 100,000 years are likely to be most like those that existed between 300,000 
and 400,000 years ago (Forester et al. 1996, p. 1).
3.	In the study of climatic implications of terrestrial paleoecology (8.3.1.5.1.3), terrestrial 
studies have focused on packrat (Neotoma sp.) middens to reconstruct the history of 
vegetation changes and associated climatic variables.  This study has proceeded 
largely as described in the SCP (DOE 1988).
4.	In the study of the paleoenvironmental history of the Yucca Mountain region 
(8.3.1.5.1.4), surficial and soil studies have established depositional and erosional 
regimes in response to climatic changes.  Detailed mapping of surficial deposits was 
completed (Lundstrom et al. 1995a) as described in the SCP (DOE 1988), but 
primarily to support geomorphic, tectonic, infiltration, and engineering studies rather 
than climate studies.  Soil-properties modeling to determine the relationships between 
soil formation and climatic parameters has been deleted from the study because 
characteristics of soil formation are unlikely to provide the millennial-scale climate-
change information or changes in mean annual precipitation and temperature available 
from other lines of evidence, such as isotopic compositions of deep calcites.
	The origins of major calcite-silica vein deposits were determined in Study 8.3.1.5.2.1 
(characterization of the quaternary regional hydrology) and are described in 
Stuckless (1991), Stuckless et al. (1991), National Research Council (1992), and 
Stuckless et al. (1992).
5.	In the paleoclimate-paleoenvironmental synthesis study (8.3.1.5.1.5), current efforts 
are focused on synthesizing and corroborating the various data sets to reconstruct 
paleoclimatic conditions.  These time-sequenced reconstructions have been used to 
estimate the initial bounds for future climatic conditions and were used to calibrate the 
numeric modeling efforts simulating human-induced climatic changes.  Based on the

	climate record near Yucca Mountain and on solar and orbital forcing functions, the 
modern climate state should persist for the next 600 years.  A monsoon climate state 
should persist for the following 1,400 years, and a glacial-transition state should 
persist for more than the following 8,000 years.  Each of the climate states is 
represented by appropriate values for mean annual temperature and mean annual 
precipitation based on modern-climate analog sites in the states of Arizona, Nevada, 
New Mexico, Utah, and Washington.  For each climate state (modern, monsoon, and 
glacial transition), analog sites have been selected to represent the lower bound, mean, 
and upper bound of expected climate conditions.  Each of the nine resulting sets of 
climate conditions is being simulated by the numerical infiltration model, the site-scale 
unsaturated-zone model, and the total system performance assessment model.  This 
study has proceeded largely as described in the SCP (DOE 1988).  In FY 1999 and 
FY 2000, a climate synthesis was performed to support TSPA-SR.  The climate 
analysis estimated climatic variables for the next 10,000 years by forecasting the 
timing and nature of climate change at Yucca Mountain (USGS 2000).  The future-
climate estimates are based on an analysis of past-climate data from analog 
meteorological stations, which were selected to provide an upper and a lower climate 
bound for each future climate.  Data from these sites was used as input to the 
infiltration model (see Section 1.2.2, Changes and Status).
6.	In the characterization of future regional climate and environments study (8.3.1.5.1.6), 
limitations in numerical-modeling techniques have resulted in the realization that a full 
100,000-year simulation of future climate using the regional climate model is not 
feasible.  Instead, the regional climate model was used to simulate various possible 
future climate scenarios (such as the greenhouse state) and the conditions of the 
glacial maximum that occurred about 21,000 years ago), and to produce tallies of 
precipitation and temperature for two- to five-year periods.  These tallies are, in 
essence, snapshots in time for the climate conditions that are simulated by the model 
for the boundary conditions, such as ice cover, that describe the scenario.  The details 
of this approach are described in Schelling and Thompson (1997, pp. 118).  See also 
Section 1.1.1, Changes and Status, item 4, last paragraph.
1.4.2	Studies to Provide the Information Required on Potential Effects of Future 
Climatic Conditions on Hydrologic Characteristics (SCP Investigation 8.3.1.5.2)
Background and SCP Plans.  The objective of this investigation was to develop an 
understanding of the Quaternary regional hydrologic regime by using the reconstructions of past 
climate from Investigation 8.3.1.5.1, along with past surface-water, unsaturated zone, and 
saturated zone characterizations.  The investigation was to determine the hydrologic conditions 
during the Quaternary that differ significantly from present conditions because of changes in 
climate.  Data from this investigation were intended to assess the nature and likelihood of 
episodic climatic changes that could produce changes in the regional flow system during the next 
100,000 years.  This information, along with models of future climate conditions and estimates 
of future meteorological conditions from Investigation 8.3.1.5.1, and models of the unsaturated 
and saturated zones from the geohydrology program (SCP (DOE 1988), Section 8.3.1.2), was to 
be used to determine the effects of climate change on geohydrology.  This determination would

require the development of a relationship between climate, infiltration and recharge.  This 
investigation included two studies developed to accomplish the following:
1.	Study 8.3.1.5.2.1 (characterization of the Quaternary regional hydrology):  This study 
was to:
? Characterize the distribution of surface water, unsaturated zone infiltration and 
percolation rates, and groundwater potentiometric levels during the Quaternary 
Period in the vicinity of Yucca Mountain
? Investigate the hydraulic characteristics of paleofloods and compare them with 
modern flooding and geomorphic processes to improve knowledge of the 
relationships between climate and flooding
? Assess the character and severity of potential flood and debris hazards for the 
repository during the preclosure period
? Determine the past infiltration and percolation history at Yucca Mountain by 
analyzing the isotopic and chemical characteristics of water from the unsaturated 
zone
? Characterize the hydrogeologic units in the regional groundwater discharge areas 
of the Amargosa Desert and Death Valley
? Understand the past quantity and quality of water in the discharge areas of 
Franklin Lake, Amargosa Desert-River, and Peters Playa
? Determine the location and hydrogeologic characteristics of paleospring deposits 
and the amount of discharge by evapotranspiration that has occurred at past 
discharge sites
? Determine past groundwater levels in carbonate caverns as evidence of past 
hydrologic conditions
? Use information about past and present discharge areas to help predict the future 
saturated zone hydrologic system at Yucca Mountain
? Conduct analog recharge studies to estimate the conditions and rates of 
groundwater recharge (infiltration) during the Quaternary near Yucca Mountain
? Determine the ages, distribution, origin, and paleohydrologic significance of 
calcite and opaline silica vein deposits along faults and fractures in the vicinity of 
Yucca Mountain.
2.	Study 8.3.1.5.2.2 (characterization of future regional hydrology due to climate 
changes):  This study was to:
? Characterize the impacts of potential future climate changes on the regional and 
site surface-water system, the site unsaturated zone hydrology, and the regional 
and site saturated zone hydrology
? Simulate past changes in run off and surface-water storage (lakes) resulting from 
past climatic change using precipitation-run off models calibrated to modern 
surface-water conditions
? Use the relationship between paleoclimate and paleo surface-water conditions to 
predict the impact of future climatic conditions on surface-water hydrology at the 
site
? Quantitatively predict the potential effects of future climatic conditions on 
infiltration, percolation, and the degree of saturation of the unsaturated zone at 
Yucca Mountain
? Reconstruct paleohydrologic conditions at Yucca Mountain and use these 
conditions together with the reconstructed paleoclimatic conditions to predict the 
impact of future climatic conditions on the saturated zone
? Use numerical-simulation techniques to synthesize existing paleohydrologic data 
and to determine the effects of greater recharge on water-table altitude, 
groundwater flow paths, and hydraulic gradients.
Changes and Status.  The objectives of this investigation have not changed since the SCP 
(DOE 1988) was issued.  However, the investigation has been modified to take advantage of data 
available from other sources.  For example, the objectives of characterizing the hydrogeologic 
units in the regional groundwater discharge areas and predicting the effects of future climatic 
conditions have been accomplished through collaboration with SCP Studies 8.3.1.2.1.3 and 
8.3.1.2.1.4.  In these studies, data from outside sources were used to construct hydrogeologic 
framework and numerical flow models of the regional groundwater-flow system 
(see Section 1.1.1 of this report) and those models are being used to investigate the effects of 
possible future climate.  Further, the characterization of past discharge areas has been 
accomplished through collaboration with SCP Study 8.3.1.5.1.2 (Paleoclimate Study:  Lake, 
Playa, and Marsh Deposits).  Changes that have occurred in the investigation are summarized 
below:
1.	The Quaternary regional hydrology study (8.3.1.5.2.1) has changed significantly since 
the SCP was issued.  For example, the Quaternary unsaturated zone hydrochemical 
analysis planned originally under this study has been transferred to Study 8.3.1.2.2.7 
(Characterization of the Unsaturated Zone Hydrochemistry).  Further, although a study 
of paleoflooding and the potential for future extreme flooding was conducted in 
Coyote Wash at Yucca Mountain (Glancy 1994), additional, site-specific studies of 
alluvial deposits in neighboring washes were not conducted, and only limited studies 
were conducted in the region surrounding Yucca Mountain (Grasso 1996).  This is 
because there was less concern about flood and debris hazards potentially impacting 
the ESF or surface facilities after the ESF was reconfigured from vertical shafts to 
ramps and drifts, and the entrances (portals) were relocated from Coyote Wash to 
Midway Valley.  As reported in the Technical Basis Report for Surface 
Characteristics, Preclosure Hydrology, and Erosion (YMP 1995a, p. 2-12), the 
locations of the ESF north and south portals are outside of the flood-prone area for the 
probable maximum flood.  Overall, the report concluded that flooding of the 
repository by extreme run off during the preclosure period was extremely unlikely 
given the location and elevation of the ESF.
	Much of the work planned for the evaluation of past discharge areas has been 
completed (Paces, Whelan et al. 1997).  This includes remote sensing of pedogenic 
carbonate deposits, vegetation, and fracture zones; measurement of discharge from 
springs and seeps; measurement of water levels in wells, caverns, and springs; studies 
of past water levels in carbonate caverns; chemical and isotopic analysis of hydrogenic 
deposits; and studies of ostracode ecology.  However, some characterization work 
described in the SCP (DOE 1988) either has not been conducted or has been 
accomplished under other studies.  For example, a drilling program to sample 
subsurface materials was not implemented because subsurface sampling also was 
being conducted under Study 8.3.1.5.1.2 (Paleoclimate Study:  Lake, Playa, and Marsh 
Deposits).  Instead, the study of paleodischarge deposits continued through FY 2000 
and FY 2001 in connection with the Nye County drilling program in the northern 
Amargosa Desert.  Also, the characterization of hydrogeologic units in the regional 
groundwater discharge area has been accomplished using available data under 
Study 8.3.1.2.1.3 (Characterization of The Regional Groundwater Flow System).
	In contrast, efforts to characterize surficial pedogenic deposits and the history and 
origin of paleosprings and lake ecology have expanded significantly in scope and 
complexity (see Progress Reports #11 and #12, Section 3.4.7, Activity 8.3.1.5.2.1.3 
(DOE 1995a; 1995b)).  The expansion was necessary because of concern that the 
deposits originated from discharge of groundwater from the saturated zone at higher 
elevations and in more recent times than had been hypothesized at the time the SCP 
was written (Progress Report #13, Section 3.4.7, Activity 8.3.1.5.2.1.3 (DOE 1996b)).  
Deposits in about 50 playas in the Yucca Mountain region have been sampled for 
ostracode ecology and for chemical and isotopic analysis (Progress Report #9, 
Section 2.2.4.7 (DOE 1994b)).  In addition, for selected sites, interdisciplinary, 
reconnaissance-level stratigraphic, sedimentologic, geochronologic, isotopic, and 
paleontologic studies have been conducted (Paces, Forester et al. 1996, pp. ii, 2, 
and 3).  Efforts to determine the origin and age of hydrogenic deposits have expanded 
to determine fluctuations in the elevation of the regional water table and the extent of 
groundwater discharge during the last several glacial cycles (Paces, Forester 
et al. 1996, p. 19).  Past water-table levels and past groundwater discharge are crucial 
for predicting the probability of such conditions recurring during the repository 
postclosure period.  These studies have been enhanced and advanced considerably 
through application of state-of-the-science isotopic methods including strontium, 
uranium-series disequilibrium, and stable carbon and oxygen analyses (Paces, Mahan 
et al. 1995, p. 1).
	Although the analog-recharge study was terminated prior to full implementation of the 
four or five sites envisioned in the SCP (DOE 1988), useful results were obtained from 
two small watersheds in south-central Nevada that were instrumented and studied for 
several years (Lichty and McKinley 1995).  Results obtained from the 
3-Springs/Kawich site (annual precipitation 250-350 mm/yr) and the East Steward 
Creek site (annual precipitation 500-700 mm/yr) were judged to be sufficient to meet 
study objectives.  Because of the difficulties associated with obtaining sufficient data 
to support low-error precipitation-run off and chloride-mass-balance modeling at the 
drier site (Kawich), no additional dry-end analog sites were studied.  In addition, a 
study of an arid-zone, monsoonal site in Arizona was initiated but then terminated 
because of resource constraints before any significant results could be obtained.
	Studies of calcite and opaline-silica vein deposits have been expanded substantially in 
scope and complexity.  Whereas the SCP (DOE 1988) outlined sampling and analysis 
of fault and fracture fillings found in trenches, natural exposures, drill cores, and 
spring and pedogenic deposits (Stuckless 1991; Stuckless et al. 1991; National 
Research Council 1992; Stuckless et al. 1992), the current study has undertaken an 
intensive effort to sample and analyze occurrences of secondary calcite and silica in 
fractures, fault zones, and lithophysal cavities in the ESF.  This expansion was in 
response to a need to reconstruct the history of percolation in the Topopah Spring Tuff 
at the potential repository horizon to support performance-assessment and design 
issues.  This work has been facilitated by recent advances in petrographic and isotopic 
sampling and analytical methods, and by ready access to the rock mass afforded by the 
ESF ramp and drift configuration.  Although the study has focused on the repository 
horizon, representative samples have been collected from the entire length of the ESF 
as excavation proceeded.  The study has concentrated on the application of strontium 
and stable carbon and oxygen isotope ratios to determine the source of water and the 
mode of mineral deposition, uranium-series and radiocarbon dating methods to 
determine timing of mineral deposition, and petrographic examination to determine the 
sequence of mineral deposition (Paces, Neymark et al. 1996, pp. 2 and 5).  The goal of 
these studies is to use the history and distribution of secondary-mineral deposition in 
the deep unsaturated zone to estimate or bound percolation rates through the repository 
block over the past several hundred thousand years (Paces, Peterman et al. 1999).
	Early estimates of the abundance of secondary minerals in the ESF indicated that the 
minimum value of the average percolation rate over the last 12.7 million years has 
been about 2 mm/year (Paces, Neymark et al. 1996, p. 3).  Refined estimates of 
percolation flux are about 1.4 mm/year based on the deposition of calcite and about 
2.5 mm/year based on deposition of opal (Paces, Marshall et al. 1997, Appendix F).  
More recent analysis has shown that percolation flux values from secondary-mineral 
deposition correlate well with estimates from the infiltration model in the TCw above 
the PTn (Marshall et al. 1998, p. 129 and Figure 1).  However, there was no 
correlation between the two methods for the TSw below the PTn.  These results 
suggest that percolation is diverted laterally or substantially redistributed by the PTn.
		In FY 2000, aspects of the ESF fracture-mineral studies continued.  Geochronologic, 
isotopic, geochemical, and petrographic analyses of calcite and opal deposited in 
fractures and cavities in the Cross Drift were integrated with the comparable data set 
for the rest of the ESF to produce an integrated record of the effects of climate change.  
A study of the primary fluid inclusions in calcite deposited in fractures and cavities 
continued to provide constraints on the thermal history of the rock mass at the 
repository horizon.
	During FY 2001, the available data on secondary calcite and silica deposits in the 
unsaturated zone were re-evaluated to determine whether the source water originated 
from the land surface or up-welled from deep in the subsurface.  The data collectively 
indicate that the mineral coatings were formed in a unsaturated zone setting that has 
been hydrologically stable over million-year time scales (see Section 3.3.1 of Progress 
Report 24 (in progress).  In addition, results of an intense study of the sporadic 
distribution of secondary mineral deposits on fracture footwalls and on lithophysal-
cavity floors were consistent with fracture flow processes in a unsaturated zone setting 
and inconsistent with a rise in the water table.  In the fluid-inclusion studies, a study 
conducted by UNLV corroborated Project findings that mineral precipitation is 
consistent with formation from low temperature, surficial fluids rather than saturation 
of the site by upwelling hydrothermal fluids.  More recent work using the 235U/207Pb 
age dating indicates that fluids with elevated temperatures have not been present in the 
unsaturated zone at Yucca Mountain since about 1.9 million years ago and most likely 
not since 6 to 8 million years ago.
2.	In the study of effects of climate changes on future regional hydrology (8.3.1.5.2.2), 
efforts to develop precipitation-run off models of modern surface-water conditions and 
basin characteristics were terminated because run off occurs so infrequently that 
collecting data sets sufficient to calibrate the models was not feasible.  Regional 
ground-water modeling studies (DAgnese, OBrien et al. 1997, pp. 5056) did not 
require run off data for calibration because a direct relationship between precipitation 
and groundwater recharge was used.  The impact of future climate on the groundwater 
system was identified as more important for evaluating repository performance than 
the impact of future climate on the surface-water system.  Consequently, plans to use 
these models to predict future run off conditions resulting from hypothesized climatic 
change also were dropped from the characterization program.  For the Viability 
Assessment of a Repository at Yucca Mountain (DOE 1998a, Volume 1, Chapter 2, 
Section 2.2.4.5), the effects of possible future climatic conditions on the regional 
groundwater system were evaluated using output from the regional climate model 
(Section 1.4.1, Study 8.3.1.5.1.6, above) under Study 8.3.1.2.1.4 (see Section 3.1.4 of 
Progress Report 16 (DOE 1997a), and Section 1.1.1 of this report).  The regional 
groundwater flow model is being expanded and upgraded as indicated in Section 1.1.1, 
Study 8.3.1.2.1.4 of this report.  However, at present, there are no plans to use the 
expanded and upgraded model to simulate Quaternary or possible future climatic 
conditions.
1.5	EROSION PROGRAM (SCP SECTION 8.3.1.6)
Data available when the SCP (DOE 1988) was written suggested that the potential repository 
could be constructed deeper than the minimum depth of 200 m and that erosion was unlikely to 
uncover or affect the repository at the planned depth (DOE 1986, pp. 6-252 and 6-253).  
Long-term average upland and hillslope erosion rates had been established for the southern Great 
Basin and many of the parameters necessary to estimate erosion rates in the region had been 
obtained from ongoing scientific studies at the Nevada Test Site.  Few of these data, however, 
were specific to the potential repository site.  Therefore, the erosion program was designed to 
provide representative, site-specific data about present and past locations and rates of erosion, 
effects of future climatic conditions and future tectonic activity on locations and rates of erosion, 
and potential effects of erosion on selected other site features and processes.
The investigations included in the erosion program are summarized in the following sections.
1.5.1	Studies to Determine the Distribution and Characterization of Present and Past 
Erosion (SCP Investigation 8.3.1.6.1)
Background and SCP Plans.  The objectives of this investigation were to identify the erosional 
processes that have been operating in the Yucca Mountain area during the Quaternary Period to 
identify the specific locations of past erosion and to quantify the rates of the different processes 
and assess their relative importance.  This investigation included one study developed to 
accomplish the following:
Study 8.3.1.6.1.1 (distribution and characteristics of present and past erosion):  This study was 
to:
? Determine the areal distribution of active erosional areas and geomorphically stable 
areas and determine the spatial distribution of the different types of geomorphic 
processes and associated deposits
? Determine stream-incision rates on Fortymile Wash and selected tributaries and 
determine the cause(s) of the major downcutting episode(s) on Fortymile Wash
? Determine the average rates of Quaternary hillslope erosion on Yucca Mountain in 
bedrock and surficial deposits and determine the genesis and rates of movement of 
hillslope deposits.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The SCP, however, described a more extensive program of data 
collection.  The studies for this investigation have evolved based on technical information 
obtained from laboratory and field studies, model development and data application activities of 
the site characterization program.  Rapidly increasing scientific understanding, along with 
periodic TSPAs have enabled focusing the ongoing site characterization program on the 
remaining uncertainties that are significant to the design, operation and safe performance of the 
potential repository (DOE 1994a).  Reevaluation and prioritization of Project needs 
(DOE 1994a) has been a continuous process based on scientific judgment and resource 
availability, governed by scientific criteria to ensure that data needed for site description, 
performance assessment, and design purposes were collected and analyzed.  Data-collection 
redundancy and overlap have been eliminated.  The data-collection needs have been further 
analyzed and refined as additional knowledge has been gained through years of site 
characterization activities.  This process has resulted in the following changes to the 
investigation.
All objectives identified in the SCP (DOE 1988) have been fulfilled to address the DOE siting 
guidelines (10 CFR 960) and the NRC performance requirements (10 CFR 60) as specified in 
these regulations.  Some of this information was reported to the NRC in a topical report 
(YMP 1993) containing the DOE evaluation of the extreme erosion potentially adverse 
condition, and in the responses to the NRC staff comments on the Extreme Erosion Topical 
Report (Brocoum 1995).  The balance of the information was documented in supplemental 
responses contained in a 1996 letter (Younker 1996a, Enclosure Revised Deliverable #T6507, 
Appendices A and B).  Other parts of the information were:
? Presented in the Technical Basis Report for Surface Characteristics, Preclosure 
Hydrology, and Erosion (YMP 1995a)
? Fulfilled with surrogate information gathered under other SCP Programs
? Rendered unnecessary based on early stages of the investigation and evaluation of the 
need for additional data to support assessments of performance of the potential 
repository.
Quaternary denudation rates on hillslopes and stream incision rates in the major alluvial system 
at Fortymile Wash confirmed the DOE expectations and indicated that no additional data 
collection was required.  In 1991, DOE decided to document the results obtained in a topical 
report (YMP 1993) as planned in Investigation 8.3.1.6.4, terminate data collection, and not 
implement Investigations 8.3.1.6.2 and 8.3.1.6.3.  The NRC was informed that study plans would 
not to be developed for the erosion program (Delligatti and Kouts 1994, Attachment 5).
The work for the erosion program began in the 1980s under a U.S. Geological Survey Scientific 
Investigation Plan (Whitney 1987) and later through SCP (DOE 1988) study plans that had been 
prepared for other programs of the SCP (the Preclosure Tectonics Program, Study 
Plan 8.3.1.17.4.6, Quaternary Faulting in the Site Area; the Preclosure Hydrology Program, 
Study Plan 8.3.1.16.1.1, Characterization of Flood Potential at the Yucca Mountain Site; and 
the Climate Program, Study Plan 8.3.1.5.1.4, Analysis of the Paleoenvironmental History of the 
Yucca Mountain Region).  Data gathered under these studies were used to describe erosional 
processes, measure the extent of erosion, and calculate erosion rates.  The erosion rate estimates 
and information demonstrating the overall stability of the landscape indicated that additional 
analysis and data collection were unnecessary.  These results were documented in the Extreme 
Erosion Topical Report (YMP 1993).  Similar interpretations were described in the Technical 
Basis Report for Surface Characteristics, Preclosure Hydrology, and Erosion which stated:  
Studies of erosional processes at the Yucca Mountain Site suggest that the landscape at the 
Yucca Mountain Site has changed very little during the past several hundred thousand years due 
to erosion. (YMP 1995a, p. 5-1).
Because of NRC staff concerns with the age estimation method used by DOE to determine ages 
of colluvial boulder deposits, the DOE authorized a modest program to collect cosmogenic ages 
for selected deposits (Younker 1996a, Enclosure Revised Deliverable #T6507, Appendix A) 
under Study 8.3.1.5.1.4 (analysis of the paleoenvironmental history of the Yucca Mountain 
region).  Information from this study corroborated the ages determined previously and support 
DOEs conclusions about the erosion rates, and the age and stability of the landscape 
(YMP 1995a, p. 5-1).  Given the proposed depth of the potential repository of at least 200 m 
(YMP 1995a, pp. 4-1 and 4-2), and based on the stability of the landscape and the very low rates 
of hillslope erosion (YMP 1993, p. viii; 1995a, p. 4-23), the DOE determined that it is unlikely 
that hillslope erosion poses a significant risk to repository performance.
In Study 8.3.1.6.1.1 data were obtained from other studies to determine the age of alluvial 
deposits and stream incision rates in Fortymile Wash and Midway Valley, and the age of 
colluvial boulder deposits and erosion rates on hillslopes.  Information on the depth of stream 
incision, stream gradients, and lithologic composition of gravels in the Fortymile Wash drainage 
system was collected under studies in the climate program and is reported in Lundstrom and 
Warren (1994).  Dating of surficial alluvium, soils, and terraces was reported in Paces, Mahan 
et al. (1995) and is discussed in a letter (Younker 1996a, Enclosure Revised 
Deliverable #T6507, Appendix B).  Volumes of denuded sediment were calculated.  An abstract 
by Coe, Whitney et al. (1992) estimated volumes of sediment removed from the western 
slope-face of Yucca Mountain.  A volumetric analysis of Quaternary alluvium removed in 
Midway Valley based on the results of surficial deposits mapping in Study 8.3.1.5.1.4 was 
reported in a letter (Younker 1996a, Enclosure Revised Deliverable #T6507, Appendix B).
1.5.2	Potential Effects of Future Climatic Conditions on Locations and Rates of Erosion 
(SCP Investigation 8.3.1.6.2)
Background and SCP Plans.  The objectives of this investigation were to determine the effects 
of future climatic conditions on the locations and rates of erosion, especially areas with the 
potential for increased erosion or stream incision, and apply the results to the evaluation of site 
processes that could degrade the surface marker system.  This investigation includes one study to 
accomplish the following:
Study 8.3.1.6.2.1 (potential effects of future climatic conditions on locations and rates of 
erosion):  This study was to determine the effects of future climatic conditions on the locations 
and rates of erosion by integrating Quaternary climate conditions and rates of surface erosion 
with predicted conditions of future climate, and by estimating significant changes in the 
character, distribution, and rates of surface erosion in the Yucca Mountain region over the next 
10,000 to 100,000 years.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  However, on the basis of data collected in other site 
characterization programs and analyses done for Investigation 8.3.1.6.1, DOE determined that 
erosion rates are extremely low and that the potential impacts on repository system performance 
are negligible.  Thus, the DOE decided not to implement Investigation 8.3.1.6.2 (DOE 1994a), 
and the NRC was informed that study plans would not be developed (Delligatti and Kouts 1994, 
Attachment 5).
The present locations and rates of surface erosion and their relationships to present climate are 
discussed in the Extreme Erosion Topical Report (YMP 1993), Coe, Glancy et al. (1995), and 
Whitney and Harrington (1993, see pp. 10151017 in particular).  The distribution and 
characteristics of past erosion and their relationships to past climatic conditions are discussed in 
Glancy (1994), Whitney and Harrington (1993, p. 1017), and in a letter (Younker 1996a, 
Enclosure Revised Deliverable #T6507, Appendices A and B).  DOE concluded that climatic 
influences on erosion are minimal.  Climate fluctuations of the type that can be discerned over 
the last 10,000 to 100,000 years with proxy data from the geologic record bound the expectation 
for future conditions.  DOEs data and analyses support the conclusion presented in the Extreme 
Erosion Topical Report (YMP 1993, Table 5) that erosion rates have been very low during the 
last half of the Quaternary Period.  In fact the erosion rate is so low that DOE concluded that the 
potentially adverse condition, evidence of extreme erosion during the Quaternary Period 
(10 CFR 60.122(c)(16)), is not present at the site (YMP 1993), and erosion is unlikely to have 
any significant impact on performance of the potential repository.
1.5.3	Studies to Provide the Information Required to Determine the Potential Effects of 
Future Tectonic Activity on Locations and Rates of Erosion 
(SCP Investigation 8.3.1.6.3)
Background and SCP Plans.  The objectives of this investigation were to identify the potential 
effects of tectonic activity on erosion at Yucca Mountain during the postclosure period by 
defining those components of erosion that were dependent upon tectonic activity, determining 
how future tectonic adjustment might influence local incision rates, and applying the results to 
the assessment of the potential for degradation of the surface marker system.  This investigation 
included one study developed to accomplish the following:
Study 8.3.1.6.3.1 (evaluation of the effects of future tectonic activity on erosion at Yucca 
Mountain):  This study consists of a single synthesis activity that was intended to estimate the:
? Effects of tectonic activity on erosion over the repository postclosure period using 
probable future tectonic scenarios for the Yucca Mountain region
? Locations and rates of present and past erosion for present climatic conditions
? Effects of future climatic conditions on erosion.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  However, on the basis of data collected in other site 
characterization programs and analyses done for Investigation 8.3.1.6.1, DOE determined that 
erosion rates are extremely low and that the potential impacts on repository system performance 
are negligible.  Thus the DOE decided not to implement Investigation 8.3.1.6.3, and the NRC 
was officially informed that study plans would not be developed (Delligatti and Kouts 1994, 
Attachment 5).
The intent of the study to evaluate the effects of future tectonic activity on erosion at Yucca 
Mountain (8.3.1.6.3.1) was fulfilled by work performed under Investigation 8.3.1.17.4.  The ages 
of exhumed fault line scarps on the Solitario Canyon and Windy Wash faults were calculated 
with cosmogenic carbon-14 (Harrington et al. 1994; also YMP 1995a, pp. 4-15 and 4-16).  
Erosion rates are so low at Yucca Mountain that these scarps show only minor modification after 
a minimum exposure age of 20,000 years.  The tectonic model synthesis, including the 
probability and expected magnitude of faulting in the Yucca Mountain area during the 
postclosure period, was evaluated under Investigation 8.3.1.17.4 and is reported in Whitney 
(1996, Chapters 8, 9, and 10).
1.5.4	Potential Effects of Erosion on Hydrologic, Geochemical, and Rock Characteristics 
(SCP Investigation 8.3.1.6.4)
Background and SCP Plans.  The objectives of this investigation were to assemble data 
showing the expected effects of erosion on the hydrologic, geochemical, and rock characteristics 
of the controlled area; and on the ability of the Monitored Geologic Repository (MGR) to 
effectively isolate waste over 10,000 and 100,000 years after disposal.  The results of this 
investigation were intended to be reported in a topical report describing the effects of erosion on 
the geohydrology, rock characteristics, and geochemistry of the site.  This investigation included 
one study developed to accomplish the following:
Study 8.3.1.6.4.1 (development of a topical report to address the effects of erosion on the 
hydrologic, geochemical, and rock characteristics at Yucca Mountain):  This study was to 
assemble data showing the expected effects of erosion on the hydrologic, geochemical, and rock 
characteristics of the controlled area; and on the ability of the MGR to effectively isolate waste 
over 10,000 and 100,000 years after disposal.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  Although the plans for the studies identified in this investigation 
were not developed, the main study objectives identified in the SCP have been accomplished as 
described in the discussions under investigations 8.3.1.6.1, 8.3.1.6.2, and 8.3.1.6.3.
DOE completed the topical report on extreme erosion (YMP 1993) and used the report to fulfill 
the intention described in the SCP (DOE 1988).  A second topical report will not be developed 
because of the extremely low erosion rates determined for the arid region and the 
erosion-resistant rock type at Yucca Mountain.  Potential performance impacts from erosion over 
time were discussed in the supplemental responses to the NRC comments (Brocoum 1995, 
pp. 3940) on the Extreme Erosion Topical Report.  Rates of erosion at Yucca Mountain have 
been shown to be so low (YMP 1993, p. viii; Brocoum 1995, pp. 3940) that it is extremely 
unlikely that erosion could remove enough overburden to impact repository system performance.
1.6	ROCK DISSOLUTION PROGRAM (SCP SECTION 8.3.1.7)
The objective of this investigation was satisfied by the information presented in the Yucca 
Mountain Environmental Assessment (DOE 1986).
The investigation included in the rock dissolution program is summarized in the following 
section.
1.6.1	Rates of Dissolution of Crystalline and Noncrystalline Components in Tuff 
(SCP Investigation 8.3.1.7.1)
The objectives of this investigation were satisfied by the information presented in the Yucca 
Mountain Environmental Assessment (DOE 1986).  Therefore, no additional testing was 
proposed in the SCP (DOE 1988).  The potential for dissolution to occur in conjunction with 
thermally driven fluid flow and condensation in the repository environment is being addressed in 
the altered zone study (see Section 1.15 of this report).
1.7	POSTCLOSURE TECTONICS PROGRAM (SCP SECTION 8.3.1.8)
The postclosure tectonics program specified in the SCP (DOE 1988) was predicated on 
performance and design requirements (e.g., 10 CFR 60.122 and 10 CFR 960.4-2-7) to 
investigate, and provide data about, the probabilities and effects of tectonic initiating events 
that might alter existing conditions at Yucca Mountain and adversely affect repository 
performance.  Four data collection investigations were identified and included in the postclosure 
tectonics program.  Because many elements of these investigations have been consolidated since 
the SCP was issued (Revision 11, Site Characterization Program Baseline [YMP 1994a]), the 
summaries for Investigations 8.3.1.8.2, 8.3.1.8.3, and 8.3.1.8.4 have been combined into 
Subsection 1.7.2 of this report.
The investigations included in the postclosure tectonics program are summarized in the 
following sections.
1.7.1	Studies to Provide Information Required on Direct Releases Resulting from 
Volcanic Activity (SCP Investigation 8.3.1.8.1)
Background and SCP Plans.  The purpose of this investigation was to assess the probability of 
future volcanic activity with respect to siting a repository for storage of high-level radioactive 
waste at Yucca Mountain and gather data on the effects of a potential volcanic eruption should 
such an eruption penetrate the site.  This investigation included two studies developed to 
accomplish the following:
1.	Study 8.3.1.8.1.1 (probability of a volcanic eruption penetrating the repository):  This 
study was to:
? Synthesize the data collected by other activities on the dating, location, and 
volume of late Cenozoic volcanic events in the region surrounding the site
? Investigate time-space patterns of past volcanic activity in the Yucca Mountain 
region and the possible structural controls of volcanic centers and potential future 
volcanic centers at and adjacent to Yucca Mountain
? Use statistical methods to evaluate geophysical data to assess the significance of 
possible local and regional structures on the area ratio of probability calculation
? Review geophysical and geochemical data collected near the site to assess 
whether there were any indications of the presence of crustal bodies that could be 
the source of future volcanic activity
? Revise the estimates of the probability of volcanic disruption of a repository site 
at Yucca Mountain.
2.	Study 8.3.1.8.1.2 (effects of a volcanic eruption penetrating the repository):  This 
study was to summarize the effects of a Strombolian eruption on a repository, and 
obtain geological parameters for the disruption of a repository by magmatic activity 
accompanied by hydrovolcanic (magma-water) explosions.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The SCP, however, described a more extensive program of data 
collection.  The studies for this investigation have evolved based on technical information 
obtained from laboratory and field studies, model development and data application activities of 
the site characterization program.  Rapidly increasing scientific understanding, along with 
periodic TSPAs have enabled focusing the ongoing site characterization program on the 
remaining uncertainties that are significant to the design, operation and safe performance of the 
potential repository (DOE 1994a).  Reevaluation and prioritization of Project needs 
(DOE 1994a) has been a continuous process based on scientific judgment and resource 
availability, governed by scientific criteria to ensure that data needed for site description, 
performance assessment, and design purposes were collected and analyzed.  Data-collection 
redundancy and overlap have been eliminated.  The data-collection needs have been further 
analyzed and refined as additional knowledge has been gained through years of site 
characterization activities.  This process has resulted in the following changes to the 
investigation.
1.	In the probability of a volcanic eruption penetrating the repository study (8.3.1.8.1.1), 
the main objective (to estimate the probability of disruption of a repository) has 
remained the same since the SCP (DOE 1988) was issued.  Data on the location and 
timing of volcanic events were incorporated into the Probabilistic Volcanic Hazard 
Analysis for Yucca Mountain, Nevada (CRWMS M&O 1996b, p. 3-2).  The study of 
the presence of magma bodies in the vicinity of the site using geophysical techniques 
was performed by the geophysics program (Activity 8.3.1.4.2.1.2) and, through 
tomographic inversions of seismic data, by the seismic monitoring program 
(Study 8.3.1.17.4.1).  Calculations of the probability of a volcanic eruption penetrating 
the repository were completed using currently available data.  A final set of probability 
calculations using only qualified data obtained in Study 8.3.1.8.5.1 (characterization of 
volcanic features) was deferred indefinitely, but this item was revisited as part of the 
development of the abstraction and testing of disruptive events in FY 1999 (see Work 
Package 13012175M9).  Probability studies were augmented and tested in 1995 
through use of the expert elicitation process.  The results of the expert elicitation were 
reported in the Probabilistic Volcanic Hazard Analysis (CRWMS M&O 1996b).  
(See Section 3.6.1 of Progress Report #15, DOE 1997b.)  Information from this study 
was used to develop an AMR that described the framework for igneous activity near 
Yucca Mountain.  This AMR supports the evaluation of disruptive events for 
TSPA-SR.  Late in FY 2001 an evaluation and interpretation of aeromagnetic data was 
initiated (Blakely et al. 2000]) from a recent survey by Nye County.  The evaluation 
and interpretation is being done by the USGS, and the results will be documented in an 
Open File Report that is expected to be available in the second quarter of FY 2002.  
DOE will evaluate the results and determine potential impacts on the igneous hazard 
estimate.  The evaluation will be documented in an update to the AMR Characterize 
Framework for Igneous Activity at Yucca Mountain, Nevada (CRWMS M&O 2000al).  
The evaluation addresses an agreement from a DOE-NRC Technical Exchange and 
Management Meeting on the Igneous Activity Key Technical Issue (Reamer and 
Williams 2000).
2.	The study of effects of a volcanic eruption penetrating the repository 
(Study 8.3.1.8.1.2) has changed substantially since the SCP was issued.  Studies of the 
effects of Strombolian and hydrovolcanic eruptions were replaced by three activities 
(eruptive effects, subsurface effects, and magma system dynamics) when the study 
plan was drafted in 1993.  The eruptive effects activity was only partially completed 
(not all measurements from analog centers were completed, nor were all data 
analyzed).  However, based on the results of the Probabilistic Volcanic Hazard 
Analysis (CRWMS M&O 1996b, Chapter 3), there appear to be no significant impacts 
from only partially completing the measurements of analog centers.  The subsurface 
effects activity, which focuses on the processes that control shallow-level intrusion 
geometries and on hydrothermal alteration in silicic tuffs near shallow basaltic 
intrusions, now includes the study of chemical and physical changes around dikes.  
A third aspect of the subsurface studies, modeling of hydrothermal processes near 
intrusions and implications for their effects on a repository, has been indefinitely 
deferred.  A new magma system dynamics study activity was added; its objectives 
were to constrain the physical processes that control magma generation and ascent and 
to determine how these processes relate to probabilistic estimates of future volcanic 
activity.  The relative importance of precisely evaluating the potential effects of a 
volcanic eruption directly penetrating the repository are related to:
? The probability of having such an event during the time period of regulatory 
concern
? The performance measure of concern
? The significance of these effects.  
TSPAs conducted to date using bounded estimates of the effects of such events indicate that the 
probability of occurrence is the most significant aspect of the impact of direct intrusive events on 
postclosure performance.
However, TSPA-SR modeling of the consequences of future igneous activity require information 
about the nature of basaltic volcanic processes that might occur at Yucca Mountain.  To provide 
this information, an AMR, Characterize Eruptive Processes at Yucca Mountain, Nevada 
(CRWMS M&O 2000am) was developed.  The scope of this AMR will be expanded in the next 
update to include documentation of an analysis of soil redistribution processes in Fortymile 
Wash to address a recent agreement from a DOE-NRC Technical Exchange and Management 
Meeting (Crump 2001).
1.7.2	Studies to Provide Information Required on Rupture of Waste Packages Due to 
Tectonic Events (SCP Investigation 8.3.1.8.2); Studies to Provide Information 
Required on Changes in Unsaturated and Saturated Zone Hydrology Due to 
Tectonic Events (SCP Investigation 8.3.1.8.3); Studies to Provide Information 
Required on Changes in Rock Geochemical Properties Resulting from Tectonic 
Processes (SCP Investigation 8.3.1.8.4)
Background and SCP Plans.  The three investigations were intended to determine the hazards 
posed to the repository by a variety of tectonic initiating events during the postclosure period.  
Once the hazards were determined, the investigations were designed to examine the potential 
effects of these hazards on waste package integrity, saturated and unsaturated zone hydrology, 
and rock mineralogical and geochemical properties during the postclosure performance period.  
The testing and modeling proposed was intended to provide data to describe and characterize the 
magnitudes and rates of tectonic processes that have operated in the past.  This information was 
to provide the basic input for geologic, geochemical, tectonic, and hydrologic models of the site.  
In turn, these models were to provide the mechanisms for analyzing scenarios that portray the 
potential future effects of tectonic processes and events that could impact repository 
performance.  Initiating events to be modeled included volcanic and igneous intrusion in the 
controlled area, faulting, uplift or tilting of rocks, and changes in stress-strain characteristics 
resulting from related tectonic or igneous events.
In Revision 11 to the Site Characterization Program Baseline (YMP 1994a, p. 8.3.1-60), the 
three investigations were reconfigured into a single study titled Tectonic Effects:  Evaluations 
of Changes in the Natural and Engineered Barrier Systems Resulting from Tectonic Processes 
and Events (Study 8.3.1.8.2.1, see Section 3.6.3 of Progress Report #16, DOE 1997a).  
As indicated in Progress Reports #10 and #11 (DOE 1994c, Section 3.6.3; 1995a, Section 3.6.3), 
the five studies that composed the three original investigations became the five activities in the 
reconfigured study, which was designed to accomplish the following:
1.	Activity 8.3.1.8.2.1.1 (formerly Study 8.3.1.8.2.1):  Collect and synthesize data to 
assess the probability and effects of tectonic processes and events that could result in 
waste package rupture and/or adverse impacts on waste-package lifetime and 
performance.
2.	Activity 8.3.1.8.2.1.2 (formerly Study 8.3.1.8.3.1):  Analyze and assess the probability 
and effects of tectonic initiating events that may result in changes in the average 
percolation flux rate at the top of the Topopah Spring welded hydrogeologic unit.
3.	Activity 8.3.1.8.2.1.3 (formerly Study 8.3.1.8.3.2):  Analyze and assess the probability 
that tectonic initiating events could result in significant changes in the elevation of the 
water table, changes in the hydraulic gradient, the creation of discharge points in the 
controlled area, or the creation of perched aquifers in the controlled area.
4.	Activity 8.3.1.8.2.1.4 (formerly Study 8.3.1.8.3.3):  Analyze possible changes in 
fracture permeability and effective porosity caused by tectonic events and processes.
5.	Activity 8.3.1.8.2.1.5 (formerly Study 8.3.1.8.4.1):  Assess possible local changes in 
the distribution of rock geochemical properties resulting from tectonic processes and 
events.
Changes and Status.  The objectives of the investigations (now the reorganized study) have not 
changed since the SCP (DOE 1988) was issued.  The results of multifaceted studies required as 
inputs to modeling and assessments needed to determine the impacts of tectonic events on the 
hydrologic system were items of early focus of the site characterization studies.  Studies of 
volcanic and tectonic effects have been coordinated with performance assessment scenario 
development and consequence analyses over the past several years.  Preliminary geologic, 
geochemical, tectonic and hydrologic models of the site have been developed.  Probabilistic 
estimates of the magmatic disruption probability have been reported in the Probabilistic 
Volcanic Hazard Analysis for Yucca Mountain, Nevada (CRWMS M&O 1996b).  This analysis 
quantified the probability and uncertainty of volcanic disruption of the repository using formal 
expert elicitation.  As discussed in the description of Investigations 8.3.1.17.3 and 8.3.1.17.4 
(Sections 3.13.8 and 3.13.9 of Progress Report #16, DOE 1997a), characterization of seismic 
hazards is being completed.  In 1998, a probabilistic seismic hazard analysis (USGS 1998) 
provided the basis for assessing the magnitudes and rates of tectonic processes.  Event trees that 
form the basis for scenario development for volcanism and tectonics are now complete.  To date, 
preliminary disruptive scenarios for volcanism, reported in TSPA - 1991 (Barnard et al. 1992; 
Eslinger et al. 1993) and TSPA - 1993 (CRWMS M&O 1994a; Wilson et al. 1994), indicate that 
volcanic effects are not significant to system performance.  Changes that have occurred in 
implementation of the reorganized study are summarized below:
1.	In the effect of tectonics on waste-package lifetime and performance activity 
(8.3.1.8.2.1.1), the potential for basaltic volcanism in the Southwest Nevada Volcanic 
Field and the implications for Yucca Mountain were analyzed (see Progress 
Report #10, Section 2.2.6.3 (DOE 1994c)).  However, the analysis did not address 
waste-package lifetime or performance, but a conceptual model of the relation 
between tectonism and volcanism in the Yucca Mountain region was developed (see 
Progress Report #11 (DOE 1995a, Section 3.6.3)).  The model refers to factors that 
affect the probability of magmatic intrusion through the repository block.  No 
additional work is planned for this study.  Separate from this study, the Waste Package 
Design team is developing a calculation that examines the effects of magma on waste 
packages to support the disruptive events process model report (PMR) and TSPA-SR.  
This work is being extended to address an agreement reached at a DOE-NRC 
Technical Exchange and Management Meeting (Krier 2001) and related to evaluation 
of magma-waste package interactions.
2.	In the effect of tectonics on percolation flux activity (8.3.1.8.2.1.2), a scoping study of 
the effect of tectonic activity (principally faulting) on the hydrologic system was 
initiated in preparation for numerical modeling of tectonic effects (Progress 
Report #11, Section 3.6.3 (DOE 1995a)).  However, the scoping study was never 
completed because it was not significant to the development of tectonic scenarios.  
Although the numerical modeling of tectonic effects on percolation flux has been 
deferred (Progress Report #13, Section 3.6.3 (DOE 1996b)), results of the scoping 
study and the cross-sectional modeling under Activity 8.3.1.8.2.1.3 are being used to 
help develop tectonic scenarios that may affect the rate of fluid movement in 
performance assessment calculations.  Separate from this study, an AMR was 
developed to describe the effects of fault displacement on transport in the unsaturated 
zone (CRWMS M&O 2000an).  This AMR supports the disruptive events PMR 
(CRWMS M&O 2000ap) and TSPA-SR.
3.	In the effect of tectonics on the saturated zone and perched water activity 
(8.3.1.8.2.1.3), a scoping study of the effect of tectonic activity (principally faulting) 
on the hydrologic system was initiated in preparation for numerical modeling of 
tectonic effects.  However, the scoping study was never completed because it was not 
significant to the development of tectonic scenarios.  Further, two-dimensional, 
cross-sectional numerical modeling of coupled fluid and heat flow in the saturated 
zone was used to analyze three alternative conceptual models for the large hydraulic 
gradient (see Progress Report #13, Section 3.6.3 (DOE 1996b)).  In addition, a 
preliminary scoping study was conducted of the hydrologic setting under Yucca 
Mountain to assess how occurrences of perched water may be affected by repository 
thermal loading and tectonic processes (see Progress Report #14, Section 3.6.3 
(DOE 1996c)).  The occurrence of perched water in boreholes USW UZ-1 and 
USW UZ-14 was analyzed, as well as its possible implications with respect to lateral 
flow along the top of the basal vitrophyre of the Topopah Spring Tuff beneath the 
repository area (see Section 3.6.3 of Progress Report #16, DOE 1997a).  Although 
additional numerical modeling has been deferred, results of the scoping study and the 
cross-sectional modeling are being used to help develop scenarios of tectonic activity 
that may affect the rate of fluid movement in performance assessment calculations.  
For example, Barr et al. (1996, p. i) present a comprehensive set of scenarios that 
connect tectonic events with radionuclide releases through logical and physically 
possible combinations or sequences of features, events, and processes.  The effects of 
these tectonic events include a wide range of hydrologic effects such as changes in 
pathways and flow rates in the unsaturated and saturated zones, changes in the 
water-table configuration, and changes in the development of perched water.  The 
scenarios are intended to guide performance assessment analyses and ensure that all 
important aspects of possible system disturbance by tectonic processes are captured in 
numerical analyses.  Barr et al. (1996, pp. 9196) also discuss a number of open issues 
for which further data and analyses would be necessary to establish their importance.  
The adequacy of the scenario-development approach will depend on the outcome of 
performance assessment analyses that capture the tectonic features, events, and 
processes that are described by the scenarios.  Separate from this study, an AMR 
describing screening of features, events, and processes is being developed to support 
the disruptive events PMR and TSPA-SR.
	For TSPA-VA, DOE began applying a scenario-development method that will 
document all features, events, and processes in the analysis (DOE 1998a, Volume 3, 
Section 4.4).  Implementation of this scenario-development method is incomplete at 
present, partly because new information must be considered as it becomes available.  
To date, basaltic igneous activity, seismic activity, and nuclear criticality have been 
identified as the disruptive features, events, and processes to be used in scenario 
construction, based on evaluations using the generalized event trees.  Seismic activity 
is now considered a normal event because of its probability, rather than a disruptive 
event.
4.	In the effect of tectonics on fracture permeability and effective porosity activity 
(8.3.1.8.2.1.4), possible buried geologic features were analyzed, as well as conditions 
that may be causing the large hydraulic gradient in the saturated zone just north of 
Yucca Mountain (see Progress Report #10, Section 2.2.6.3 (DOE 1994c)).  
Two-dimensional, cross-sectional numerical modeling of coupled fluid and heat flow 
in the saturated zone was used to analyze these features and conditions (see Progress 
Report #13, Section 3.6.3 [DOE 1996b]).  Although additional numerical modeling 
has been deferred, results of scoping studies and the cross-sectional modeling are 
being used to help develop scenarios of tectonic activity that may affect the rate of 
fluid movement in performance assessment calculations.  The rationale and 
methodology for development of tectonic-process scenarios are described in Barr 
et al. (1996, pp. 2 and 3).
5.	In the effect of tectonics on rock geochemical properties (Activity 8.3.1.8.2.1.5), no 
work has been performed, and none is planned.  Observations of rock geochemical 
properties indicate significant spatial variability.  Bounded estimates of changes in 
rock geochemistry induced by potential tectonic events are considered to be well 
within the bounds of natural variability.  In addition, modified rock geochemistry 
would primarily affect the retardation characteristics of the geologic media along 
likely paths of radionuclide transport.  Observations also indicate that tectonic 
processes or events would be unlikely to significantly change the retardation 
characteristics.
1.7.3	Studies to Provide the Information Required by the Analysis and Assessment 
Investigations of the Tectonics Program (SCP Investigation 8.3.1.8.5)
Background and SCP Plans.  The objectives of this investigation were to provide refined data 
on the age, location, and volume of young volcanic rocks in the vicinity of the site; gather data 
concerning the presence of thermal anomalies in the area and data on the geochemical and 
physical effects of intrusions on the surrounding rock; and establish the regional pattern and rate 
of Neogene folding.  This investigation included three studies developed to accomplish the 
following:
1.	Study 8.3.1.8.5.1 (characterization of volcanic features):  This study was to:
? Investigate, through drilling, the origin of four aeromagnetic anomalies found in 
Crater Flat and the Amargosa Valley that may represent shallowly buried basaltic 
or silicic volcanic centers or intrusive bodies
? Establish the chronology of basaltic volcanism and the youngest silicic volcanic 
activity in the Yucca Mountain region
? Establish the field geologic relations and the eruptive history of basaltic volcanic 
centers in the Yucca Mountain region
? Determine the geochemistry of scoria sequences of different ages at the Lathrop 
Wells center and older centers in the Crater Flat area
? Determine the time-space geochemical variations of the volcanic fields of the 
southern Great Basin.
2.	Study 8.3.1.8.5.2 (characterization of igneous intrusive features):  This study was to:
? Determine the depth of the curie temperature isotherm by analyses of existing 
magnetic survey data
? Collect data on the nature and extent of chemical and physical changes that may 
occur in the surrounding tuffs as a result of the intrusion of dikes or sills
? Evaluate the local ambient heat flow and local heat flow anomalies in relation to 
Quaternary igneous bodies.
3.	Study 8.3.1.8.5.3 (investigation of folds in Miocene and younger rocks of the region):  
This study was to establish the pattern, rate, amplitude, and wavelength of post-middle 
Miocene folding in the region.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The SCP, however, described a more extensive program of data 
collection.  The studies for this investigation have evolved based on technical information 
obtained from laboratory and field studies, model development and data application activities of 
the site characterization program.  Rapidly increasing scientific understanding, along with 
periodic TSPA, have enabled focusing the ongoing site characterization program on the 
remaining uncertainties that are significant to the design, operation and safe performance of the 
potential repository (DOE 1994a).  Reevaluation and prioritization of Project needs 
(DOE 1994a) has been a continuous process based on scientific judgment and resource 
availability, governed by scientific criteria to ensure that data needed for site description, 
performance assessment, and design purposes were collected and analyzed.  Data-collection 
redundancy and overlap have been eliminated.  The data-collection needs have been further 
analyzed and refined as additional knowledge has been gained through years of site 
characterization activities.  This process has resulted in the following changes to the 
investigation:
1.	The main objectives of the characterization of volcanic features study (8.3.1.8.5.1), to 
provide field geologic, geochronologic, and geochemical data for volcanism 
probability calculations, have not changed.  However, the methods used to collect the 
information were modified to take advantage of information available from other 
sources.  Late in FY 2001 an evaluation and interpretation of aeromagnetic data was 
initiated (Blakely et al. 2000) from a recent survey by Nye County.  The evaluation 
and interpretation is being done by the USGS, and the results will be documented in an

	Open File Report that is expected by be available in the second quarter of FY 2002.  
DOE will evaluate the results and determine potential impacts on the igneous hazard 
estimate.  The evaluation will be documented in an update to the AMR Characterize 
Framework for Igneous Activity at Yucca Mountain, Nevada (CRWMS M&O 2000al).  
The evaluation addresses an agreement from a DOE-NRC Technical Exchange and 
Management Meeting on the Igneous Activity Key Technical Issue (Reamer and 
Williams 2000).  Drilling of aeromagnetic anomalies to characterize the composition, 
age, and volume of possible buried volcanic centers in the Yucca Mountain region has 
been indefinitely deferred.  The study of geochemical variations in basaltic volcanic 
fields to determine whether volcanism is waxing or waning in the Yucca Mountain 
region was only partially completed (data were gathered but not analyzed because of 
resource constraints).  The geochronology studies to determine the age of the youngest 
silicic volcanism in the Yucca Mountain region were not implemented.  Instead, the 
Project will use geochronologic data from non-Project sources.
2.	The objectives of the study to characterize igneous intrusive features (8.3.1.8.5.2) have 
not changed.  Sufficient information was available with which to define reasonable 
bounds on the probability of future magmatic events in the Yucca Mountain region for 
the TSPA-SR.  This information has been used and documented in the Probabilistic 
Volcanic Hazard Analysis (CRWMS M&O 1996b), which was conducted to assess the 
probability of disruption of the potential repository by a volcanic event and to quantify 
the uncertainties associated with this assessment.  The judgments of members of a 
ten-person expert panel were elicited to ensure that a wide range of approaches was 
considered in the hazard analysis.  Results of the individual elicitations were combined 
to develop an integrated assessment of the volcanic hazard that reflects the diversity of 
alternative scientific interpretations (DOE 1998a, Volume 3, Subsection 4.4.2).  The 
assessment focused on the volcanic hazard at the site expressed as the probability of 
disruption of the repository.  It provides an assessment of volcanic risk, which 
expresses the probability of increased radionuclide release because of volcanic 
disruption.  Information from this study has been used to develop an AMR that 
describes the characteristics of eruptive processes (CRWMS M&O 2000am).  In 
addition, to support the TSPA-SR analysis of igneous consequences, Dike 
Propagation Near Drifts (CRWMS M&O 2000ao) was changed.  This AMR 
specifically examined the characteristics of a potential future igneous event 
intersecting the repository but not including eruptive activity.  As a result of an 
agreement from the DOE-NRC Technical Exchange and Management Meeting on the 
Igneous Activity Key Technical Issue (Krier, 2001), DOE is planning work to develop 
detailed process models of the effects of intersection of repository drifts by an 
ascending basaltic dike.
3.	The study of folds in Miocene and younger rocks of the region (8.3.1.8.5.3) was 
deferred because active folding was judged not to be a significant factor affecting 
repository performance.

1.8	HUMAN INTERFERENCE PROGRAM (SCP SECTION 8.3.1.9)
The postclosure human interference program was developed to address:
? The likelihood of inadvertent human intrusion into a monitored geologic repository
? Interference with long-term MGR performance because of human activities
? The possible consequences of such interference events.
The investigations included in the human interference program are summarized in the following 
sections.
1.8.1	Studies to Provide the Information Required on Natural Phenomena and Human 
Activities That Might Degrade Surface Markers and Monuments (SCP 
Investigation 8.3.1.9.1)
Background and SCP Plans.  The objectives of this investigation were to provide information 
on active or potentially active natural processes at Yucca Mountain capable of adversely 
affecting the long-term-survivability of the surface marker system, and use the data to determine 
the most suitable locations for the surface markers and monuments.  This investigation included 
one study developed to accomplish the following:
Study 8.3.1.9.1.1 (an evaluation of natural processes that could affect the long-term survivability 
of the surface marker system at Yucca Mountain):  This study was to:
? Identify the potential locations of faulting and volcanic eruption or intrusion that could 
occur and affect the marker system
? Determine the effects of future erosion and deposition on the topographic elements of 
the controlled area boundary at Yucca Mountain.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The SCP, however, described a more extensive program of data 
collection.  The studies for this investigation have evolved based on technical information 
obtained from laboratory and field studies, model development and data application activities of 
the site characterization program.  Rapidly increasing scientific understanding, along with 
periodic TSPA, have enabled focusing the ongoing site characterization program on the 
remaining uncertainties that are significant to the design, operation and safe performance of the 
potential repository (DOE 1994a).  Reevaluation and prioritization of Project needs 
(DOE 1994a) has been a continuous process based on scientific judgment and resource 
availability, governed by scientific criteria to ensure that data needed for site description, 
performance assessment, and design purposes were collected and analyzed.  Data-collection 
redundancy and overlap have been eliminated.  The data-collection needs have been further 
analyzed and refined as additional knowledge has been gained through years of site 
characterization activities.
The study to identify natural events that could disrupt or destroy the surface marker system 
(8.3.1.9.1.1) was completed generally as described in the SCP (DOE 1988).  Information 
concerning natural processes that could affect the long-term survivability of the surface marker 
system at Yucca Mountain has been summarized and included in a report (Fehr et al. 1996; DOE 
1997c).  Suitable locations for the surface marker and monument system were determined as 
described in the SCP.
1.8.2	Studies to Provide the Information Required on Present and Future Value of 
Energy, Mineral, Land, and Groundwater Resources (SCP Investigation 8.3.1.9.2)
Background and SCP Plan.  The objectives of this investigation were to identify and assess the 
natural resource potential at the potential repository site at Yucca Mountain; to collect available 
data to estimate the future supply, demand, and value of the groundwater resource in southern 
Nevada, proximal to Yucca Mountain; and to apply the results to determine the likelihood for 
future exploratory drilling within the boundaries of the perimeter drift.  This investigation 
included two studies developed to accomplish the following:
1.	Study 8.3.1.9.2.1 (natural resource assessment of Yucca Mountain, Nye County, 
Nevada):  This study was to:
? Conduct a geochemical sampling program to evaluate the potential for precious, 
base, and strategic metals; energy resources; and industrial mineral resources in 
the vicinity of Yucca Mountain
? Examine and qualitatively evaluate the available geophysical data base to 
determine whether any geophysical anomalies are present that may require 
additional exploration and possibly constrain any known geochemical anomalies
? Characterize the local geothermal regime as it might relate to repository 
performance during the postclosure period and assess the geothermal regime in 
terms of its energy resource potential for either hydrothermal or conductive 
reservoir thermal systems
? Determine the potential for the presence or absence of suitable source rocks, 
reservoir rocks, and traps and seals at and near the site
? Determine the potential for occurrence of conventional hydrocarbon resources at 
and near the site, and provide data for an overall mineral and energy resource 
assessment
? Complete an overall mineral and energy resource assessment that identifies 
mineral resources with current markets, calculates gross and net values for 
identified reserves and resources, and evaluates the resource potential of any 
identified or undiscovered mineral and energy resources.
2.	Study 8.3.1.9.2.2 (water resource assessment of Yucca Mountain, Nevada):  This study 
was to assess the current and projected supply and demand situation for groundwater 
in the geohydrologic study area and estimate the value of the groundwater resource.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The scope has been expanded, however, to include studies 
formerly included in Investigation 8.3.1.9.3.  Given the proposed treatment of human-induced, 
potentially disruptive scenarios (commonly referred to as human intrusion) identified by the 
National Academy of Sciences, the Project plans to use a stylized human intrusion scenario and 
compare the long-term performance results with the undisturbed scenario analyses.  The use of a 
stylized scenario precludes the need to precisely identify the probability of having each 
individual human intrusion event correlated with the attractiveness of the site for potential future 
drilling.
1.	Studies to provide the information required on present and future value of energy and 
mineral resources (Study Plan 8.3.1.9.2.1) have been completed using standard 
industry practices.  The results of the assessment of geothermal resources were 
reported by Flynn et al. (1996), and the results of the assessment of industrial rocks 
and minerals resources were reported by Castor and Lock (1995).  A geochemical 
sampling program was implemented as part of the metallic resources study and 
preliminary investigations on hydrocarbon resources were reported in Grow 
et al. (1994), and industrial natural resources were evaluated in Castor and 
Lock (1995).  An AMR report on natural resources is planned to document all the 
studies planned in the SCP (DOE 1988) for the natural resources part of the human 
interference program.  The scope of this study has been expanded to include work 
formerly included in Study 8.3.1.9.3.1.  A section on natural resources was included in 
the Yucca Mountain Site Description (CRWMS M&O 2000c, Section 4.9).
2.	Studies to provide the information required on present and future value of groundwater 
resources (Study Plan 8.3.1.9.2.2) have been or are being implemented using standard 
industry practices.  The availability, quality, potential uses, and demand for water 
resources in the area surrounding Yucca Mountain was studied, but the investigation 
was less extensive and used more modern methods than discussed in Study 
Plan 8.3.1.9.2.2.  In addition, Nye and Clark counties have developed sophisticated 
demographic and water-demand forecasts.  Therefore, it may be unnecessary for the 
Project to produce these forecasts.  The scope of this study has been expanded to 
include work formerly included in Study 8.3.1.9.3.2.
1.8.3	Studies to Provide Information Required on Potential Effects of Exploiting Natural 
Resources on Hydrologic, Geochemical, and Rock Characteristics (SCP 
Investigation 8.3.1.9.3)
Background and SCP Plans.  The objectives of this investigation were to assess the likelihood 
of inadvertent human interference in the vicinity of Yucca Mountain by evaluating the potential 
effects of exploration for, or extraction of, natural resources on the hydrologic characteristics of 
Yucca Mountain; and use the results of these assessments as input for expert judgment to 
estimate the bounds on the probability of inadvertent human interference with, and intrusion into, 
the potential repository.  This investigation included two studies developed to accomplish the 
following:
1.	Study 8.3.1.9.3.1 (evaluation of data needed to support an assessment of the likelihood 
of future inadvertent human intrusion at Yucca Mountain as a result of exploration for 
and/or extraction of natural resources):  This study was to: 
?	Determine the maximum drilling density and frequency (drillholes per square 
kilometer per 10,000 years) that can be reasonably assumed for a repository at 
Yucca Mountain
?	Determine the extent to which future groundwater withdrawals will modify the 
expected ground-water flow paths.
2.	Study 8.3.1.9.3.2 (an evaluation of the potential effects of exploration for, or 
extraction of, natural resources on the hydrologic characteristics of Yucca Mountain):  
This study was to:
? Determine the potential effects of future groundwater withdrawals on the 
hydrologic system at Yucca Mountain
? Demonstrate that those initiating events identified in the SCP (DOE 1988) for the 
human interference issue are not considered sufficiently credible or significant to 
necessitate additional investigation
? Document this evaluation in a topical report.
Changes and Status.  It was determined that no unique data would be generated by this 
investigation, and the entire scope was transferred to Investigation 8.3.1.9.2.
1.	Evaluation of data needed to support an assessment of the likelihood of future 
inadvertent human intrusion as a result of exploration for and/or extraction of natural 
resources (Study 8.3.1.9.3.1) was transferred to Study 8.3.1.9.2.1 (natural resource 
assessment of Yucca Mountain, Nye County, Nevada).
2.	The study to evaluate the potential effects of exploration for, or extraction of, natural 
resources on the hydrologic characteristics of Yucca Mountain (8.3.1.9.3.2) was 
transferred to Study 8.3.1.9.2.2 (water resource assessment of Yucca Mountain, 
Nevada).  As in the case of potentially disruptive events (i.e., human intrusion) that 
may penetrate the repository horizon, other anthropogenic effects may be conceived 
that potentially modify the hydrologic characteristics of the site.  Present day 
conditions will be used to describe the biosphere pathways, and DOE intends to use 
that same logic when evaluating the potential change in hydrology by anthropogenic 
processes such as pumping or irrigation.
1.9	METEOROLOGY PROGRAM (SCP SECTION 8.3.1.12)
The purpose of the SCP (DOE 1988) meteorology program was to provide data needed to 
calculate radiological doses resulting from airborne releases from the repository during the 
preclosure operational period, to design surface facilities, and to provide hydrometeorological 
measurements for hydrologic and climatic studies.  The meteorology program was designed to:
? Determine regional meteorological conditions
? Describe atmospheric and meteorological phenomena at potential locations of surface 
facilities
? Identify population centers relative to wind patterns in the general region of the site
? Identify and describe potential extreme weather phenomena and recurrence intervals.
The investigations were created to provide an understanding of the meteorology of the area, 
including both average and extreme climatic phenomena.  These data were intended to provide 
input to the performance and design issues that assess the preclosure radiological safety aspects 
of the monitored geologic repository under normal and accident conditions.
Three of the investigations were directed at various aspects of regional-scale meteorology.  
These investigations shared common data sources and similar analyses needed to achieve their 
objectives.  Thus, investigations were combined into one planning document, the Scientific 
Investigation Implementation Package for Regional Meteorology, Revision 1 (CRWMS 
M&O 1995b, p. 1-1), as described in Section 3.8 of Progress Report #16 (DOE 1997a).
The investigations included in the meteorology program are summarized in the following 
sections.
1.9.1	Studies to Provide Data on Regional Meteorological Conditions (SCP 
Investigation 8.3.1.12.1)
Background and SCP Plan.  The purposes of this investigation were to characterize the 
regional meteorological conditions within at least 80 km of Yucca Mountain, with extension to 
Las Vegas, and to coordinate meteorological monitoring efforts with other Project 
meteorological monitoring programs.  The objectives of the investigation were to gather, 
analyze, and report relevant meteorological data; and to develop a plan that coordinates 
meteorological monitoring efforts proposed during site characterization by various Project 
participants.
Two studies were developed to accomplish data collection and coordination of meteorological 
monitoring:
1.	Study 8.3.1.12.1.1 (characterization of the regional meteorological conditions):  This 
study was to provide for acquiring and analyzing appropriate meteorological data and 
results from relevant studies; and describe regional meteorological characteristics in a 
summary report.
2.	Study 8.3.1.12.1.2 (plan for synthesis of Yucca Mountain Project meteorological 
monitoring):  This study was to develop a plan that would coordinate meteorological 
monitoring efforts initiated through Characterization Programs 8.3.1.12 
(Meteorology), 8.3.1.5 (Climate), 8.3.1.2 (Geohydrology), and 8.3.1.16 (Preclosure 
hydrology).
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The work in this investigation was combined with work from 
related regional meteorology characterization investigations 8.3.1.12.3 and 8.3.1.12.4.  These 
other investigations address regional airflow patterns relative to local population centers, and 
provide meteorological information needed for the engineering design of surface facilities and 
for support of radiological dose calculations.  The consolidated work plan was developed as 
Scientific Investigation Implementation Package for Regional Meteorology (CRWMS 
M&O 1995b, p. 1-1), and the study concluded at the end of FY 1997.
1.9.2	Studies to Provide Data on Atmospheric and Meteorological Phenomena at 
Potential Locations of Surface Facilities (SCP Investigation 8.3.1.12.2)
Background and SCP Plans.  The purpose of this investigation was to provide site-specific 
meteorological data to Project investigators working on a variety of site characterization 
activities.  Applications include calculating radiological doses to workers, including workers in 
restricted areas, and the general public under routine and accident scenarios.  The objective of 
the investigation was to conduct meteorological monitoring at Yucca Mountain to provide data 
that can be used in resolving design and performance issues associated with preclosure 
radiological safety.  The investigation includes one study that was developed to accomplish the 
following work.
Study 8.3.1.12.2.1 (meteorological data collection at the Yucca Mountain site):  This study was 
to:
? Collect meteorological data at potential locations of surface facilities and at a sufficient 
number of additional locations deemed necessary to characterize the wind flow patterns 
in the vicinity of Yucca Mountain
? Process the meteorological data collected into a format and content that will be useful in 
assessing radiological impacts, as required by the design and performance issues.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The work for this investigation is controlled by Study 
Plan 8.3.1.12.2.1.
In the activity to collect and process meteorological data (8.3.1.12.2.1), the network was 
expanded from five to nine stations during 1992.  Modernization changes have been made to 
ensure that the data content and quality meet the current regulatory monitoring requirements 
applicable to input data for atmospheric dispersion models.  The modernization changes are 
consistent with the SCP objectives and ensure that the objectives are being met.
During 1997 and 1998, the technical staff performing the monitoring and reporting associated 
with this study assumed field operations and data processing responsibilities for 17 recording 
precipitation gauge stations previously operated under the USGS in Study 8.3.1.2.1.1 
(Section 3.1.1 of Progress Report #16, DOE 1997a).  The monitoring responsibility was resumed 
by the USGS in 1999.
1.9.3	Studies to Provide Data on the Location of Population Centers Relative to Wind 
Patterns in the General Region of the Site (SCP Investigation 8.3.1.12.3)
Background and SCP Plans.  The purpose of this investigation was to characterize regional 
wind flow patterns relative to population centers in the vicinity of Yucca Mountain.  This 
investigation uses data from other regional meteorology and socioeconomic investigations.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The work in this investigation was combined with work from 
related regional meteorology characterization investigations 8.3.1.12.1 and 8.3.1.12.4.  This 
work is described under Investigation 8.3.1.12.1.
1.9.4	Studies to Provide Data on Potential Extreme Weather Phenomena and Their 
Recurrence Intervals (SCP Investigation 8.3.1.12.4)
Background and SCP Plan.  The purpose of this investigation was to provide meteorological 
data required for engineering design of surface facilities.  This investigation included a single 
study developed to accomplish the following work.
Study 8.3.1.12.4.1 (characterize the potential extreme weather phenomena and their recurrence 
intervals):  This study was to evaluate the existing historical, meteorological, and climatological 
records, technical publications, and other relevant information to quantify the extreme weather 
phenomena that may be expected at the Yucca Mountain site and determine recurrence intervals.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The focus on extreme weather events was expanded to include the 
typical conditions needed by the design engineers.  The work in this investigation was combined 
with work from related regional meteorology characterization investigations 8.3.1.12.1 and 
8.3.1.12.3.  This work is described under Investigation 8.3.1.12.1.
1.10	OFFSITE INSTALLATIONS AND OPERATIONS PROGRAM (SCP 
SECTION 8.3.1.13)
The purpose of the SCP (DOE 1988) offsite installations program was to provide data about the 
operations of facilities that could produce radiological exposures to the public or to site workers 
as consequences of either normal operations or accidental releases.  The investigations included 
in the offsite installations and operations program are summarized in the following sections.
1.10.1	Determination of Nearby Industrial, Transportation, and Military Installations 
and Operations (Nuclear And Nonnuclear) (SCP Investigation 8.3.1.13.1)
Background and SCP Plans.  The objectives of this investigation were to identify and assess 
the potential impacts on preclosure performance and design from nearby DOE industrial, 
transportation, and military operations.  This investigation included three data collection 
activities developed to accomplish the following:
1.	Activity 8.3.1.13.1.1 (identify near-site activities):  This activity was to identify and 
describe all DOE, industrial, commercial, transportation, and military operations 
within 8 km of the Yucca Mountain site; and evaluate significant operations outside 
this area that could impact the site.
2.	Activity 8.3.1.13.1.2 (characterize nuclear fuel cycle facilities in the area):  This 
activity was to identify all nuclear fuel cycle facilities within 80 km of the Yucca 
Mountain site or within Nevada areas adjacent to Las Vegas.
3.	Activity 8.3.1.13.1.3 (characterize all nuclear facilities not associated with the fuel 
cycle near the Yucca Mountain site):  This activity was to characterize the impacts of 
all radiological operations at facilities within 80 km of the Yucca Mountain site that 
are not part of the nuclear fuel cycle.
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The activities described in the SCP to meet these objectives were 
initiated in FY 1998, and preliminary results were incorporated into the Viability Assessment in 
FY 1999.  Additional efforts are planned during FY 2000 for incorporation into the appropriate 
sections of the site description document and site recommendation documentation.  None of the 
activities has changed since the SCP was issued.
1.10.2	Potential Impacts of Nearby Installations and Operations (SCP 
Investigation 8.3.1.13.2)
Background and SCP Plans.  The objective of this investigation was to use the data collected in 
Investigation 8.3.1.13.1 to assess the impacts that may result from accidents involving any 
nearby installations and operations.  The potential accidents include radiological and 
nonradiological events that may impact site operations.  This investigation included four 
activities developed to accomplish the following:
1.	Activity 8.3.1.13.2.1 (evaluate near-site activities):  This activity was to:
? Review all commercial, DOE, U.S. Department of Defense, and transportation 
operations within 8 km of the site
? Identify those operations that could act as accident initiators
? Quantify the probabilities and magnitudes.
2.	Activity 8.3.1.13.2.2 (evaluation of the impact of nuclear fuel cycle operations near the 
Yucca Mountain site and Las Vegas):  This activity was to determine the impact of all 
nuclear fuel cycle operations within 80 km of the Yucca Mountain site by determining 
routine yearly releases of radioactive material from all such facilities based on 
information in safety documentation; and determine the probabilities and magnitudes 
of potential accidents at the facilities based on past technical reports and safety 
analysis documentation.
3.	Activity 8.3.1.13.2.3 (evaluate the impact of all nuclear facilities not associated with 
the nuclear fuel cycle near the Yucca Mountain site):  This activity was to use data 
from Activity 8.3.1.13.1.3 to determine airborne concentrations and estimate the 
probability of such concentrations resulting from operations within 80 km of Yucca 
Mountain.  These estimates provide the basis to estimate potential for exposure of 
individuals in Las Vegas, Nevada.
4.	Activity 8.3.1.13.2.4 (evaluate the impact of ground motion from nuclear testing 
activities at the Nevada Test Site):  This activity was to evaluate the impact of ground 
motion from nuclear testing activities at the Nevada Test Site.  As described in the 
SCP (DOE 1988, p. 8.3.1.13-11) this activity was addressed in the resolution of 
Investigation 8.3.1.17.3 (studies to provide required information on vibratory ground 
motion that could affect repository design or performance).
Changes and Status.  The primary objectives of this investigation have not changed since the 
SCP (DOE 1988) was issued.  The activities described in the SCP to meet these objectives were 
initiated in FY 1998, and preliminary results were incorporated into the Viability Assessment in 
FY 1999.  Additional efforts are planned during FY 2000 for incorporation into the appropriate 
sections of the site description document and site recommendation documentation.
1.	The activity to review all transportation operations near the site and assess their 
potential as accident initiators (8.3.1.13.2.1) has not changed since the SCP was 
issued.
2.	The activity to evaluate the impact of nuclear fuel cycle operations within 80 km of the 
site and in Las Vegas (8.3.1.13.2.2) has not changed since the SCP was issued.
3.	The activity to characterize impacts of radiological operations within 80 km of the site 
that are not associated with the nuclear fuel cycle (8.3.1.13.2.3) has not changed since 
the SCP was issued.
4.	As noted above, the activity to evaluate the impact of ground motion from nuclear 
testing is to be addressed in SCP Investigation 8.3.1.17.3.
1.11	SURFACE CHARACTERISTICS PROGRAM (SCP SECTION 8.3.1.14)
The SCP surface characteristics program was developed to provide data to ensure that potential 
repository surface facilities, including openings to the underground, protected public health and 
safety, were technically feasible, and could be constructed at reasonable costs.
The investigations included in the surface characteristics program are summarized in the 
following sections.
1.11.1	Studies to Provide Topographic Characteristics of Potential Locations of Surface 
Facilities (SCP Investigation 8.3.1.14.1)
Background and SCP Plan.  The SCP (DOE 1988) objective for this investigation was to 
determine the surface elevation and relief at the potential surface facility locations to provide a 
basis for evaluating the:
? Surface drainage, flood levels, and erosion characteristics in the vicinity of Yucca 
Mountain
? Cut-and-fill requirements for the design and engineering of the repository surface 
facilities
? Stability of natural slopes and cut slopes.
Topographic maps were to be used in locating surface facilities, roads, and railways.
The SCP (DOE 1988, p. 8.3.1.14-18) stated that no studies were needed or planned for 
Investigation 8.3.1.14.1 (topography) because the requirements for this investigation had been 
satisfied.  The SCP also stated (p. 8.3.1.14-25) that no further studies, tests, or analyses were 
planned.
Changes and Status.  Surface hydrologic studies are planned to support license application 
design for repository surface facilities.  Issues to be addressed include drainage pattern 
modification by engineered structures and earthwork, flood hazard, and erosion effects.
1.11.2	Studies to Provide Soil and Rock Properties of Potential Locations of Surface 
Facilities (SCP Investigation 8.3.1.14.2)
Background and SCP Plans.  The objectives of this investigation were to:
? Conduct an exploration program for characterization of the soil and rock conditions that 
will influence, or be influenced by, the construction of surface facilities
? Conduct laboratory tests and material property measurements on representative samples 
of soil and rock
? Conduct field tests and characterization measurements to determine the in situ physical, 
mechanical, and dynamic properties of the soil and rock
? Apply the results.
This investigation included three studies developed to accomplish the following:
1.	Study 8.3.1.14.2.1 (exploration program):  This study was to:
? Review existing site information and conduct a field reconnaissance for the 
purpose of establishing a preliminary exploration program to include subsurface 
drilling, test pits, trenching, and geophysical methods
? Obtain sufficient subsurface data to identify or verify the types, locations, and 
principal dimensions of all major surface structures needed by the proposed 
project
? Fill any gaps in the previous preliminary exploration activity and make such 
additional explorations necessary to define adequately the subsurface conditions.
2.	Study 8.3.1.14.2.2 (laboratory tests and material property measurements):  This study 
was to measure the soil or rock weight and volume components using physical 
property tests; and measure in the laboratory the static and dynamic deformation and 
strength characteristics of soil and rock samples obtained from the exploratory 
program.
3.	Study 8.3.1.14.2.3 (field tests and characterization measurements):  This study was to
? Classify and describe the soil and rock conditions in the field and determine their 
physical properties
? Measure the deformation and strength characteristics of in situ soil and rock 
conditions
? Use geophysical methods to measure in situ soil and rock properties, profile the 
alluvium-bedrock contact, locate discontinuities or other structural abnormalities, 
and determine the depth, thickness, and lateral extent of soil and rock stratigraphic 
units.
Changes and Status.  The objectives have not changed since the SCP (DOE 1988) was issued.  
However, much of the data intended to be collected under this investigation has been collected 
under investigations in other site programs.
Two reports have been planned to synthesize site geotechnical data and to begin site specific 
investigations for LA design input.  The first of these, the Yucca Mountain Site Geotechnical 
Report (CRWMS M&O 1996e), was completed in FY 1996 and included a comprehensive 
synthesis of geological and geotechnical investigations to support ESF and repository subsurface 
design.  The report contains a summary of and implications of geotechnical data including 
geology, structure, hydrology, laboratory-determined rock properties, rock mass quality, and 
rock mass properties.  Minor revisions to this report were completed in March 1997 (CRWMS 
M&O 1997f).  A second report on geotechnical site characterization for the Waste Handling 
Building has been completed (CRWMS M&O 1999g) to present a synthesis of data gathered in 
previous explorations plus results of new investigations to support design of this safety related 
structure.  This report includes preliminary subsurface characterization for ground motion 
evaluations and preliminary foundation design recommendations.  Neither of these reference 
documents, which provide compilations of key information supporting the design of the 
repository and surface facilities, was specifically identified in the SCP.
The most recent round of geotechnical investigations, specifically drilling, began in the summer 
of 2000 and was completed in the summer of 2001.  Downhole, in-hole, and surface seismic 
surveys and laboratory measurements continued in 2001.  The results of these investigations 
(e.g., shear-wave velocity profiles) will be used in the calculation of ground motion at the 
location of the Waste Handling Building and the crest of Yucca Mountain.  Documentation of 
this work is in progress and is expected in July 2003.
Previous investigations (prior to FY 1996) for North Portal surface facilities include the 
following:
1.	In the exploration program study (8.3.1.14.2.1), a report (USBR 1992) was published 
that included the results of pavement mapping and core log data from UE-25 NRG#1.  
This report focused on the north ramp portal area and surface soil characterization for 
the north portal pad area.  In addition, a cross section was developed for the ESF south 
ramp using surface mapping data.
2.	In the laboratory tests and material property measurements study (8.3.1.14.2.2), 
laboratory testing was completed on samples from the north ramp geologic boreholes 
and trenches and systematic drilling boreholes for intact rock index properties, 
physical properties, mechanical properties, and thermal properties.  Laboratory and 
field tests were completed to characterize the nonlithified Rainier Mesa Tuff and 
pre-Rainier Mesa Tuff bedded tuff.  Laboratory and field tests were completed to 
characterize soil parameters for foundation design for selected north portal facilities.  
These data were submitted to the technical database.
3.	In the field tests and characterization measurements study (8.3.1.14.2.3), a report was 
completed that presents results of the engineering characterization of the pre-Rainier 
Mesa and Rainier Mesa tuffs that were encountered by the ESF north ramp (Kessel 
et al. 1994).  This report characterized the extent and estimates of mechanical 
properties of the nonwelded tuffs found locally west of the Bow Ridge fault.  A second 
report (Brechtel et al. 1995) documented the investigation for the north ramp of the 
ESF and included geology and rock structure logs for the north ramp geologic 
boreholes, cross sections with stratigraphic and thermal-mechanical units, rock 
mechanical properties, rock mass quality and rock mass mechanical properties 
estimates.  A third report (Kicker et al. 1997) included geology and rock structure logs 
for boreholes USW SD-7, USW SD-9, USW SD-12, and USW UZ-14 and 
stratigraphic cross section for the ESF main drift, rock mechanical properties, rock 
mass quality and rock mass mechanical properties estimates.
1.12	THERMAL AND MECHANICAL ROCK PROPERTIES PROGRAM (SCP 
SECTION 8.3.1.15)
The SCP (DOE 1988) thermal and mechanical rock properties program was developed to 
provide all site information needed on thermal and mechanical rock properties and on ambient 
stress and temperature conditions.  Data on these properties are needed for a variety of site 
characterization, process model development, performance assessment, and design activities.  
The data needed include:
? Thermal properties of the host rock for analyses related to waste package design
? Thermal-mechanical properties of the rock for development of rock properties models 
and repository design
? In situ stress and temperature conditions for initial and boundary conditions for design 
calculations, thermal properties of rock for disturbed zone analysis, and bulk properties 
and radon emanation for radiologic safety analysis.
The investigations included in the thermal and mechanical rock properties program are 
summarized in the following sections.
1.12.1	Studies to Provide the Required Information for Spatial Distribution of Thermal 
and Mechanical Properties (SCP Investigation 8.3.1.15.1)
Background and SCP Plans.  The objectives of this investigation were to:
? Provide laboratory characterization of thermal conductivity and heat capacity and 
describe the spatial variability of these parameters
? Provide laboratory characterization of thermal-expansion behavior and describe its 
spatial variability
? Provide laboratory characterization of mechanical properties of intact rock and describe 
spatial variabilities
? Provide laboratory characterization of mechanical properties of fractures and describe 
their spatial variabilities
? Monitor rock-mass deformation around a vertical shaft and measure horizontal in situ 
stresses
? Obtain data on in situ thermal and thermomechanical properties for thermomechanical 
units TSw1 and TSw2
? Obtain in situ measurements of the mechanical properties of the rock mass for 
thermomechanical unit TSw2
? Investigate the effects of spatial variability of the rock on drift stability, mining (tunnel) 
excavation activities, and ground supports
? Evaluate techniques for underground excavation and ground support, for selecting 
ground supports to be used in different rock types, and monitor drift stability
? Quantify the emanation of radon into drifts and observe its dispersion with airflow
? Measure parameters needed to design repository ventilation systems.
The investigation of thermal and mechanical properties is divided into eight data collection 
studies, four studies focused on properties of intact rock using laboratory methods, and four 
studies focused on properties and performance of the rock mass under repository conditions 
using in situ testing.
1.	Study 8.3.1.15.1.1 (laboratory thermal properties):  This study was to obtain laboratory 
data on:
? Density and porosity and evaluate the spatial variability of these parameters
? Volumetric heat capacity and evaluate the spatial variability of this parameter
? Thermal conductivity and evaluate the spatial variability of this parameter.
2.	Study 8.3.1.15.1.2 (laboratory thermal expansion testing):  This study was to obtain 
laboratory data for thermal-expansion behavior and evaluate the spatial variability of 
this parameter.
3.	Study 8.3.1.15.1.3 (laboratory determination of mechanical properties of intact rock):  
This study was to obtain laboratory data for the compressive mechanical properties of 
intact rock and the spatial variability of this parameter for baseline experiment 
conditions.  Evaluate the effects of varying sample size, strain rate, temperature, 
confining pressure, lithophysal content, saturation state, and anisotropy on 
compressive mechanical properties, and measure the tensile strength of 
thermomechanical unit TSw2.
4.	Study 8.3.1.15.1.4 (laboratory determination of the mechanical properties of 
fractures):  This study was to obtain data about the mechanical properties of fractures, 
and the spatial variability of this parameter for baseline experiment conditions; and 
evaluate the effects of varying normal stress, displacement rate, temperature, sample 
size, fracture roughness, and saturation state on the mechanical properties of artificial 
and natural fractures.
5.	Study 8.3.1.15.1.5 (excavation investigations):  This study was to:
? Monitor rock-mass deformation around a vertical shaft and measure horizontal in 
situ stresses
? Demonstrate constructability and stability of underground rooms with 
cross-sectional dimensions equivalent to those of a repository in both lithophysae-
rich and lithophysae-poor material
? Obtain data on the deformation response of drifts with cross-sectional dimensions 
equivalent to those of a repository in welded tuff, evaluate computer code(s), and 
demonstrate the constructability and stability of repository-sized drifts in 
lithophysae-rich and lithophysae-poor material.
6.	Study 8.3.1.15.1.6 (in situ thermomechanical properties):  This study was to:
? Estimate the in situ thermomechanical properties of lithophysae-rich tuff 
(thermomechanical unit TSw1) and to evaluate the thermal and mechanical 
response of this tuff unit to elevated temperatures
? Obtain thermal and thermomechanical rock-mass measurements of the effects of 
thermal inputs on a representative (canister-scale) waste-emplacement borehole in 
lithophysae-poor tuff (thermomechanical unit TSw2)
? Estimate in situ mechanical and thermomechanical properties of 
thermomechanical unit TSw2 and test thermomechanical computer models
? Monitor changes in thermally induced stress in jointed welded tuffs in an 
accelerated test
? Evaluate the thermomechanical response of welded tuff around repository 
openings to expected repository conditions during both construction and operation
? Develop a data base for evaluating thermal and thermomechanical design analyses 
and methods applicable for repository considerations
? Use site data in predicting drift response and support-rock interactions during 
construction, operation, retrieval, and postclosure.
7.	Study 8.3.1.15.1.7 (in situ mechanical properties):  This study was to measure the 
deformation modulus of the rock mass and evaluate the zone of increased fracturing 
adjacent to underground openings; and evaluate the mechanical behavior of the rock 
mass or its components.
8.	Study 8.3.1.15.1.8 (in situ design verification):  This study was to:
? Develop recommendations for mining (excavating) in the repository by 
monitoring and evaluating mining (excavation) activities in the ESF, and by 
conducting mining (excavation) investigations
? Develop recommendations for a ground-support methodology to be used in drifts 
in the repository, on the basis of evaluations of the ground-support methodology 
used in the ESF and on experimentation with other ground-support configurations
? Provide confidence in predictions of usability of the repository underground 
facilities over the 100-year operational life
? Contribute to evaluations of the effectiveness of mining (excavating) methods and 
ground-supports
? Calibrate and refine criteria for determining stability of the openings
? Develop techniques for monitoring stability of the repository drifts
? Measure the rate of radon emanation from the repository host rock, and evaluate 
parameters and variables needed as input to or for testing of models to be used for 
design of the ventilation systems in the repository underground facility.
Changes and Status.  The basic objectives of this investigation have not changed since the SCP 
(DOE 1988) was issued.  The laboratory testing program to determine thermal and mechanical 
properties of intact rock has been scaled down in terms of the numbers of samples to be tested 
and the spatial extent of testing.  This was primarily a result of the reevaluation and prioritization 
of project needs for performance assessment and design data (DOE 1994a; 1996a).  The spatial 
variability of rock properties was to be determined from core samples taken from systematic 
drilling program boreholes (Study Plans 8.3.1.15.1.1 through 8.3.1.15.1.4).  The number of 
boreholes has been reduced (from 12 to 4), resulting in fewer locations sampled, because of 
prioritization of work and resource constraints (DOE 1994a; DOE 1996a).  Samples collected 
from the ESF will be primarily in the TSw2, resulting in some spatial information in that unit, 
but the statistical basis for sampling, described in the SCP (DOE 1988), will not be followed 
because of schedule and resource constraints.  Limited information from boreholes was sufficient 
for input to the Viability Assessment, with more information on rock property variability to be 
developed before submittal of the license application.
The in situ testing related to the determination of rock-mass properties and behavior of the rock 
mass under repository conditions has changed because of the development of the Program 
Approach (DOE 1994a) and the modifications to the Program Plan (DOE 1996a).  The in situ 
thermal and mechanical studies (primarily study items 5 through 7 above) and the waste package 
environment studies were reevaluated to produce a new set of proposed tests that accomplished 
the same set of objectives in a more streamlined fashion.  The results of this reevaluation were 
documented in the In Situ Thermal Testing Program Strategy (DOE 1995c).  The in situ design 
verification study (study item 8 above) was implemented during construction of the ESF with 
only minor modifications.
The changes to the studies included in the thermal and mechanical properties investigation are 
described briefly below:
1.	In the laboratory thermal properties study (8.3.1.15.1.1), extensive characterization of 
density and porosity was deferred because similar measurements were being made 
elsewhere in the program (see SCP (DOE 1988) Section 8.3.1.4.3.2).  Limited heat 
capacity measurements in the TSw2 were made using the guarded heat flow meter 
method.  Experimental values compare well with theoretical values already submitted 
to the Reference Information Base (YMP 1996b).  Because it appears that heat 
capacity can be adequately predicted by theoretical methods, no additional tests are 
planned.  Thermal conductivity data on samples of TCw, PTn, TSw1, TSw2, and CHn 
thermomechanical units, and the Prow Pass and Bullfrog Tuffs from boreholes 
UE-25 NRG#4, UE-25 NRG#5, USW NRG-6, USW NRG-7, USW SD-7, USW SD-9, 
and USW SD-12 have been completed.  Additional tests of the TSw2 unit from 
samples collected from the Thermal Testing Facility and the Southern Ghost Dance 
Fault Alcove to assess spatial variability and anisotropy have been completed.
2.	In the laboratory thermal expansion testing study (8.3.1.15.1.2), unconfined and 
confined thermal expansion tests have been conducted on samples from TSw1, TSw2, 
PTn, and TCw from the north ramp geologic and systematic drilling boreholes 
(Brodsky et al. 1997, pp. 1620 and 3544).  In accordance with the SCP (DOE 1988), 
mineralogic characterizations of some specimens were performed so that a correlation 
between the silica components and thermal expansion behavior could be examined 
(Brodsky et al. 1997, pp. 24 and 5067).  Also, thermal expansion tests at elevated 
pressures were performed to examine the effects of confining pressure on nonlinear 
thermal expansion (Martin, Noel et al. 1997a).  Additional testing (thermal expansion, 
thermal conductivity, unconfined compression, and elastic modulus measurements), 
not described in the SCP, has been completed on TSw2 samples from the Thermal 
Testing Facility and the Southern Ghost Dance Fault Alcove to assess spatial 
variability and anisotropy (see Boyd, Noel et al. 1996; SNL 1996a; SNL 1997a; 
SNL 1997b; SNL 1997c; and SNL 1998).
3.	In the laboratory determination of mechanical properties of intact rock, study 
(8.3.1.15.1.3), extensive testing of basic properties has been performed on core from 
the north ramp geologic and systematic drilling boreholes (Boyd, Price et al. 1996a; 
Boyd, Price et al. 1996b; Martin, Price et al. 1994; Martin, Price et al. 1995).  Limited 
creep tests at ambient and elevated temperature have been completed (Martin, 
Noel et al. 1997b).  Effects of environmental conditions such as temperature and 
pressure have also been investigated, primarily in the TSw2 thermomechanical unit 
(Martin, Noel et al. 1997c).  Because of the need to provide data for ESF design, most 
of the study activities have focused on the TSw2.
4.	In the laboratory determination of mechanical properties of fractures study 
(8.3.1.15.1.4), borehole fracture specimens from units TCw, TSw1, TSw2, and CHn 
were tested (Olsson and Brown 1997).  Fracture tests on TSw2 rock were also 
conducted at elevated temperature, 175C (SNL 1996b).  This work is within the 
scope of testing described in the SCP (DOE 1988).
5.	In the excavation investigations study (8.3.1.15.1.5), the access convergence and 
demonstration breakout tests have been abandoned because of the change from shaft 
access to the ESF to ramp access (see Dennis 1991).  Convergence monitoring at 
selected locations in the ESF continues as part of the long-term monitoring program.  
The sequential drift mining test was included in the ESF thermal test as part of the 
development of the drift for the Drift Scale Test (see CRWMS M&O 1996f, pp. viii, 
xi, and 2-3).  Detailed planning for this test was initiated early in FY 1996.  The test 
was conducted in conjunction with construction of the Thermal Testing Facility.
6.	In the in situ thermomechanical properties study (8.3.1.15.1.6), the project reevaluated 
the thermal testing and analysis program and proposed a new, more consolidated suite 
of tests to accomplish the objectives of thermal testing.  This strategy was documented 
in the In Situ Thermal Testing Program Strategy (DOE 1995c).  The strategy was 
implemented in FY 1996 by incorporating it into this study and initiating the design 
and fielding of the first ESF thermal test.  This test was composed of two parts, a 
single heater test and a heated drift test.  These tests were identified as principal 
components of the test strategy (DOE 1995c).  The tests in the study have been 
modified as follows:
? Heater experiment in unit TSw1 (Activity 8.3.1.15.1.6.1).  A single heater test in 
TSw1 was proposed as an alternative test if the ESF construction was delayed.  
Because of rapid progress in ESF construction, this test is being deferred in favor 
of testing in the TSw2.  However, no testing was implemented during FY 1999.
? Canister-scale heater experiment (Activity 8.3.1.15.1.6.2).  This test was 
combined with some elements of other tests into the single heater test.  A detailed 
design of the single heater test was completed and documented in Test Design, 
Plans and Layout Report for the ESF Thermal Test (CRWMS M&O 1996f).  The 
test was installed in FY 1996 and started in August 1996.  During the reporting 
period, the data analyses were completed, and the final report was being prepared 
(CRWMS M&O 1999l).
? Yucca Mountain heated block (Activity 8.3.1.15.1.6.3).  The data needs and 
objectives related to this test have been combined into the Thermal Testing 
Facility, under Activity 8.3.1.15.1.6.2 and Activity 8.3.1.15.1.6.5.
? Thermal stress measurements (Activity 8.3.1.15.1.6.4).  The data needs and 
objectives related to this test have been combined into the Thermal Testing 
Facility under Activity 8.3.1.15.1.6.2 and Activity 8.3.1.15.1.6.5.
? Heated room experiment (Activity 8.3.1.15.1.6.5).  This test has been combined 
into the heated drift portion of the Thermal Testing Facility.  
Thermal mechanical-hydrological-chemical coupling is being explored in this 
test.  A preliminary test configuration has been developed and documented in Test 
Design, Plans, and Layout Report for the ESF Thermal Test (CRWMS 
M&O 1996f, pp. vii, 1-1, 1-4, 1-7 and Section 1.2.2).  The test consists of a single 
heated drift 5 m in diameter, with in-drift heater canisters to simulate waste 
packages.  To accelerate the test, wing heaters were emplaced in the ribs of the 
drift.  The heated part of the drift is approximately 50 m long.  The heat from the 
wing heaters causes the heated part to simulate a drift within a multidrift heated 
repository.  The location and type of instrumentation to be used in the test was 
specified in the test plan.  The sequential drift mining test, under 
Study 8.3.1.15.1.5 was conducted as part of the construction of the heated drift 
test.
7.	In the in situ mechanical properties study (8.3.1.15.1.7), the objectives have been 
partly incorporated into the ESF thermal tests.  A plate loading test was conducted as 
part of the heated drift test.  The test provided measurements of rock-mass modulus 
under both ambient and heated conditions.  The plate loading test is an intermittent 
test, and a second test is planned for FY 2000 with results expected in FY 2001.
8.	In the in situ design verification study (8.3.1.15.1.8), geotechnical design verification 
activities are being conducted in the north ramp and main drift of the ESF to provide 
data that can be used to confirm adequacy of design, construction, and long-term 
performance from the beginning of ESF construction.  These verification activities are 
continuing for the East-West Cross Drift with reduction of cross-drift mapping data 
and combining of that data with ESF data to get a more complete picture of the rock 
properties of each stratigraphic unit The data from these activities are being used to 
support repository design, and to validate the ESF design.  The evaluation of mining 
(excavation) methods has been limited to collection of rock mass quality data and 
monitoring of selected drill and blast operations to ensure that damage to the rock 
mass is limited.  Comparison of mining (excavation) methods for repository design 
and evaluation of controlled blasting will not be done because the repository will be 
constructed by mechanical excavation.  Monitoring of ground support systems is 
proceeding as planned, as is the monitoring of drift stability.  A small ventilation study 
was conducted to evaluate the effect of operating diesel locomotives in the tunnel.
1.12.2	Studies to Provide the Required Information for Spatial Distribution of Ambient 
Stress and Thermal Conditions (SCP Investigation 8.3.1.15.2)
Background and SCP Plans.  The objective of this investigation was to determine the spatial 
variability of ambient stress and in situ temperature to satisfy performance assessment input 
requirements for geomechanical and thermomechanical models being used for repository design.  
In addition, heat flow data was to be used, as necessary, as a check on the internal consistency of 
models of heat and water flow at Yucca Mountain.  This investigation includes two studies 
developed to accomplish the following:
1.	Study 8.3.1.15.2.1 (characterization of the site ambient stress conditions):  This study 
was to:
? Characterize the ambient (pre-repository) state of stress of the Yucca Mountain 
host rock and surrounding units for use as initial conditions for geomechanical 
models used in the design and performance assessment of the repository 
underground facilities
? Conduct anelastic strain-recovery experiments on samples from core holes to 
determine the spatial variability of horizontal stresses at Yucca Mountain
? Conduct overcore-stress experiments in the ESF to determine the in situ state of 
stress above, within, and below the repository host rock and to evaluate the extent 
to which the ambient stress conditions are redistributed adjacent to excavations.
2.	Study 8.3.1.15.2.2 (characterization of the site ambient thermal conditions):  This 
study was to:
? Characterize the ambient (pre-repository) temperature of the Yucca Mountain 
host rock and surrounding units for use as initial conditions for thermomechanical 
models used in the design and performance assessment of the repository 
underground facilities
? Measure the spatial variation of temperature with depth in existing surface-based 
boreholes and provide baseline temperatures within the repository host rock and 
surrounding units
? Measure thermal conductivity (near 25C) of core samples as a check on 
independent thermal-property determinations
? Determine heat flow at Yucca Mountain.
Changes and Status.  The objectives of this investigation have not changed significantly since 
the SCP (DOE 1988) was issued.  However, changes to the scope of work have been made to 
consolidate related studies (see DOE 1994a; 1996a).  Some of the changes resulted from the 
change from a shaft-and-main configuration for the ESF and the potential repository described in 
the SCP to the ramps-and-drift configuration now baselined.  Other changes resulted from 
DOEs efforts to reevaluate and prioritize the Projects information needs based on scientific 
criteria that considered the needs to ensure that data needed for site characterization purposes are 
collected and analyzed.  Data-collection redundancy and overlap have been eliminated.  The 
data-collection needs have been further analyzed and refined as additional knowledge has been 
gained through years of site characterization activities (DOE 1994a; 1996a).  This process has 
resulted in the following changes to the investigation.
1.	In the study of site ambient stress conditions (8.3.1.15.2.1), much of the work scope 
was developed to support design and operation of the shaft configuration for the ESF 
and potential repository.  The change in the ESF and potential repository 
configurations to ramps and drifts eliminated the need for anelastic strain-recovery 
experiments.  Further, the work scope associated with the overcore-stress experiments 
was transferred to Study 8.3.1.15.1.8 (in situ design verification) (see Section 3.11.8 of 
Progress Report #16, DOE 1997a).  Studies associated with boreholes USW G-1 and 
USW G-2 are described in Chapter 1 of the SCP (DOE 1988).  From 1981 to 1985, 
hydraulic fracturing stress measurements were conducted at depths of 0.3 to 1.7 km in 
four wells drilled in Yucca Mountain (Stock et al. 1985; Stock and Healy 1988, 
pp. 8793).  The results of recently completed hydraulic fracturing in situ stress 
measurements in a 30-m-deep test hole, ESF-AOD-HDFR#1, drilled from the Thermal 
Testing Facility, have shown that the measured horizontal stresses are only moderately 
differential and are smaller than the vertical stress.  The stress regime Sv>SH>Sh 
(where Sv, SH, and Sh are the vertical, maximum horizontal, and minimum horizontal 
principal stresses, respectively) corresponds to the locally predominant normal 
faulting.  The north-northeastern maximum horizontal stress direction is consistent 
with the average strike direction of the normal faults.  The hydraulic fracturing data 
generally corroborate the results of previous in situ stress measurements in holes 
USW G-1 and USW G-2 (Stock et al. 1985).  Both measurements indicate the same 
general conclusion:  the in situ stress regime is the normal faulting condition 
(SV > SH >Sh).  Therefore, the pre-SCP data are considered adequate to support the 
probabilistic seismic hazard analysis, TSPA, and Viability Assessment.  Additional 
hydraulic fracturing in situ stress tests have been performed in the Northern Ghost 
Dance Fault Alcove and Southern Ghost Dance Fault Alcove.  The results of these 
hydrofracture tests are consistent with test results from the Thermal Testing Facility 
and the normal faulting condition (Lee, M.Y. 1996, p. 1).
2.	In the study of site ambient thermal conditions (8.3.1.15.2.2), the work scope has been 
transferred to the closely related SCP (DOE 1988) Activity 8.3.1.8.5.2.3 (heat flow at 
Yucca Mountain and evaluation of regional ambient heat-flow anomalies).  
In addition, the overall objective of this work was changed to emphasize evaluation of 
available thermal data.  As a result, the need for additional data collection was 
minimized.  In FY 1995, a temperature log was run in borehole USW G-2, and the log 
indicated that the temperature profile in the unsaturated zone had remained unchanged 
since 1984 (see Section 3.6.9 of Progress Report #13, DOE 1996b).  This information, 
along with temperature data from several boreholes instrumented in the unsaturated 
zone as part of Study 8.3.1.2.2.3 (see Section 3.1.7 of Progress Report #16, 
DOE 1997a), indicated that additional thermal-profile data from surfaced-based 
boreholes probably are not needed.  A large number of thermal-conductivity 
measurements have been made on core samples from surface-based boreholes and the 
ESF under Activity 8.3.1.15.1.1.3 (see Section 3.11.1 of Progress Report #16, 
DOE 1997a).
	The locations at which temperature logs of horizontal boreholes will be run have 
changed since the SCP (DOE 1988) was written, primarily because of the 
reconfiguration of the ESF and guidance provided by subsurface observations.  The 
Bow Ridge fault has been tested.  More extensive testing of the Ghost Dance fault than 
that envisioned in the SCP has been completed.  Testing of the Drill Hole Wash 
structure and imbricate fault zone is not currently planned because neither of these 
fault zones passes directly through the planned emplacement area (Drill Hole Wash 
structure is at the northern end, and the imbricate fault zone is well to the east).  Also, 
resolving the relative importance of liquid versus gas-phase movement in the fault 
zones is becoming a testing priority, whereas the SCP emphasized parameter 
estimation.  Testing for liquid-water movement in fault zones, especially the Ghost 
Dance Fault, has become a testing priority because of isotopic evidence of water 
percolation in fault zones to the repository horizon (see Sections 3.1.6 and 3.1.8 of 
Progress Report #16, DOE 1997a).
1.13	PRECLOSURE HYDROLOGY PROGRAM (SCP SECTION 8.3.1.16)
The SCP preclosure hydrology program was intended to provide data to address design and 
performance issues related to potential for flooding, the availability of water for repository 
construction and operation, and the subsurface hydrologic conditions that might require 
engineering measures that are either excessively costly or beyond those reasonably available.
The investigations included in the Preclosure Hydrology Program are summarized in the 
following sections.
1.13.1	Flood Recurrence Intervals and Levels at Potential Locations of Surface Facilities 
(SCP Investigation 8.3.1.16.1)
Background and SCP Plans.  The objectives of this investigation were to determine the 
magnitudes and frequencies of major flood events that can potentially occur during the period of 
repository operation; identify all potential areas of inundation; and determine the quantities and 
size characteristics of debris transported by flooding.  This investigation included one study 
developed to accomplish the following:
Study 8.3.1.16.1.1 (characterization of flood potential of the Yucca Mountain site):  This study 
was to assess the flood and debris flow hazards at and near the potential repository surface 
facilities locations to allow adequate design of facilities to prevent or reduce hazards to an 
acceptable level.
Changes and Status.  The objectives of the preclosure hydrology program (8.3.1.16) have not 
changed significantly since the SCP (DOE 1988) was issued.  These objectives have been largely 
addressed through studies from the Geohydrology Program (8.3.1.2), and through efforts in 
support of the Technical Basis Report for Surface Characteristics, Preclosure Hydrology, and 
Erosion (YMP 1995a).  All data necessary to address the DOE and NRC performance 
requirements specified in regulations have been:
? Delivered and reported
? Fulfilled with surrogate information
? Rendered unnecessary based on early stages of the investigation and evaluation of 
performance impacts.
In the study to characterize the flood potential of the Yucca Mountain site (8.3.1.16.1.1), 
precipitation and run off data compiled largely through the above studies and data supplied in a 
National Weather Service report (Hansen et al. 1977) were used to develop several probable 
maximum flood studies that were conducted by the U.S. Bureau of Reclamation (Bullard 1992; 
Blanton 1992) and the USGS (Glancy 1994).  The results of a conservative analysis of the 
potential for flooding were reported in the Technical Basis Report for Surface Characteristics, 
Preclosure Hydrology, and Erosion (YMP 1995a, pp. 2-11, 2-16).  Estimates of water surface 
elevations associated with the probable maximum flood were shown to pose little problem of 
repository flooding.
1.13.2	Location of adequate water supplies (SCP Investigation 8.3.1.16.2)
Background and SCP Plans.  The objectives of this investigation were to locate an adequate 
water supply for construction, operation, closure, and decommissioning of an MGR at Yucca 
Mountain, Nevada; and use the information to assess the suitability of candidate wells for 
repository water supply through decommissioning of the repository.  This investigation included 
one study developed to accomplish the following:
Study 8.3.1.16.2.1 (location of adequate water supply for construction, operation, closure, and 
decommissioning of a monitored geologic repository at Yucca Mountain, Nevada):  This study 
was to:
? Assess the cost, feasibility, and adequacy of wells UE-25 J#12 and UE-25 J#13 for use 
as alternative water supply for an MGR at Yucca Mountain, Nevada
? Locate a primary water supply for an MGR at Yucca Mountain, Nevada
? Locate alternative water supplies for an MGR at Yucca Mountain, Nevada
? Identify and evaluate potential effects of repository related withdrawals on the local flow 
system at Yucca Mountain, Nevada.
Changes and Status.  The objectives of this investigation have not changed since the SCP 
(DOE 1988) was issued.  However, the methods used to collect the information were modified to 
take advantage of information available from other sources.
In the study to locate an adequate water supply for construction, operation, closure, and 
decommissioning of an MGR (8.3.1.16.2.1), the process to obtain the water permit for site 
characterization included holding hearings and collecting depositions regarding issues 
concerning use of water from wells UE-25 J#12, UE-25 J#13, and USW VH-1.  Much data and 
information regarding water budgets, aquifers, and pumping rates and drawdown were presented 
by contractors from the USGS, U.S. Park Service, and State of Nevada.  A monitoring well 
(UE-25 JF#3) was installed to monitor any potential impacts to regional water levels by water 
use from site characterization.  Additionally, site and regional water-level monitoring has been a 
continuous effort, and these data are published annually by the USGS.  These data are also 
discussed in the Technical Basis Report for Surface Characteristics, Erosion, and Preclosure 
Hydrology (YMP 1995a, pp. 3-6, 3-11).
1.13.3	Groundwater Conditions Within and Above the Potential Host Rock 
(SCP Investigation 8.3.1.16.3)
Background and SCP Plans.  The objectives of this investigation were to:
? Determine the amount of water inflow to the repository horizon including seasonal 
variations in inflow rate
? Determine the existence of perched water
? Define the locations, depths, thicknesses, and lateral extents, seasonal variations and 
degrees of saturation of any perched-water zones identified.
Characterization of the hydrologic conditions within and above the repository horizon was to be 
accomplished by studies being performed in support of Investigation 8.3.1.2.2 (studies to provide 
a description of the unsaturated zone hydrologic system of the site).  Although the bases for 
addressing the investigations are different (repository design versus long-term performance 
assessment), the parameters that must be obtained to satisfy both of these investigations are the 
same.  Data on flux, moisture content, and potential influx were to be obtained from the 
geohydrology program (8.3.1.2).  The data collected under the geohydrology program were to be 
compiled, analyzed, and evaluated under Activity 8.3.1.16.3.1.1, and were to be used to define 
the moisture conditions at the site that are needed for design.
This investigation included one study developed to accomplish the following:  Study 8.3.1.16.3.1 
(determination of the preclosure hydrologic conditions of the unsaturated zone at Yucca 
Mountain, Nevada):  This study was to synthesize data from site geohydrology program 
(8.3.1.2), to determine the preclosure hydrologic characteristics of the unsaturated zone at Yucca 
Mountain, Nevada.
Changes and Status.  The objectives of this investigation have not changed since the SCP 
(DOE 1988) was issued.  The data collection efforts were performed under the geohydrology 
program as described in the SCP (DOE 1988).  However, the data evaluation efforts were also 
largely completed under the geohydrology program to avoid having separate and redundant 
evaluations performed under Investigation 8.3.1.16.3.
The objectives of the study to determine the preclosure hydrologic conditions of the unsaturated 
zone at Yucca Mountain, Nevada (8.3.1.16.3.1) are being accomplished according to the 
description in the SCP (DOE 1988).  The data needed for this investigation are being collected 
mostly under the geohydrology program, (see Section 1.1.2 of this report), but some data are 
being compiled, analyzed, and evaluated under this study.  Characterization of the hydrologic 
conditions within and above the repository horizon is being accomplished by studies being 
performed in support of Investigation 8.3.1.2.2 (See Section 1.1.2 of this report, studies to 
provide a description of the unsaturated zone hydrologic system at the site).  Data on flux, 
moisture content, and potential influx are being obtained from the geohydrology program.  
Information obtained from new and existing boreholes is providing data concerning perched 
water, zones of saturation, and many other parameters of concern for unsaturated zone 
characterization.  The results of the study are also discussed in the Technical Basis Report for 
Surface Characteristics, Erosion, and Preclosure Hydrology (YMP 1995a, pp. 3-1, 3-5).
1.14	PRECLOSURE TECTONICS PROGRAM (SCP SECTION 8.3.1.17)
The SCP preclosure tectonics program was a comprehensive, multidisciplinary program intended 
to characterize the tectonic events and processes that could impact potential repository structures, 
systems, or components considered to be important to safety until permanent closure is achieved.  
The purpose of the program was to provide characterizations of tectonic processes and events for 
consideration in the design and operation of certain structures, systems, and components required 
for exercising the retrieval option.  The program described in the SCP (DOE 1988) was intended 
to investigate the tectonic characteristics of the site in sufficient scope and detail to provide 
reasonable assurance that the processes were understood and that the characterization parameters 
were determined with the confidences needed to support license application requirements.  
Information was provided from a variety of sources and methods including scientific literature, 
current and historical seismicity data, geologic maps, logs from boreholes and surface trenches, 
gravity surveys, aeromagnetic and paleomagnetic observations, seismic reflection and refraction 
profiles, and magneto-telluric soundings.
The investigations included in the preclosure tectonics program are summarized in the following 
sections.
1.14.1	Studies to Provide Required Information on Volcanic Activity that Could Affect 
Repository Design or Performance (SCP Investigation 8.3.1.17.1)
Background and SCP Plans.  The objectives of this investigation were to identify and evaluate 
credible volcanic hazards that could affect preclosure repository performance:  ash falls from 
distal silicic volcanic centers in the western Great Basin, and basaltic volcanic eruptions at the 
site.  The potential for silicic ash falls at the site was studied under this investigation, and the 
potential for basaltic eruptions was studied under the postclosure tectonics program (8.3.1.8).  
This investigation included one study developed to accomplish the following.
Study 8.3.1.17.1.1 (potential for ash fall at the site):  This study was to:
? Compile information on Quaternary silicic volcanism in the western Great Basin, the 
recurrence of which might produce an ash fall at the site
? Produce an approximate probability-versus-thickness function for potential ash falls at 
the site and estimate a particular ash fall thickness that has less than one chance in ten of 
occurring in 100 years
? Estimate the potential particle densities and particle-size distributions of ash falls at the 
site to support design of ventilation filters.
Changes and Status.  The primary objectives of this investigation have not changed.  The work 
described in the SCP (DOE 1988) was accomplished by compiling and evaluating information 
on silicic volcanism in the western United States (Perry and Crowe 1987; DOE 1996b).  No 
additional work is planned.
1.14.2	Provide Information on Fault Displacement that Could Affect Repository Design or 
Performance (SCP Investigation 8.3.1.17.2)
Background and SCP Plans.  This investigation was intended to provide information that could 
be used to avoid siting of facilities or waste packages in areas with potential for fault 
displacements in excess of a few inches.  The siting objective for surface faulting was to avoid 
fault displacement in excess of a few inches beneath the structural foundations of surface 
facilities considered important to safety.  The primary concern regarding faulting in the 
underground facilities during preclosure was that waste packages might be sheared or become 
jammed in their waste-emplacement boreholes, making retrieval more difficult and time 
consuming than it otherwise might be.  No single fault with the potential to create such problems 
was thought to exist, but if such a fault were identified, an attempt would be made to determine 
its location underground for consideration in the positioning of waste-emplacement boreholes.  
This investigation included one study developed to accomplish the following:
Study 8.3.1.17.2.1 (faulting potential at the repository):  This study was to assess the:
? Stability of the site surface with respect to fault displacement at locations proposed for 
facilities important to safety and demonstrate, with a high degree of confidence, that 
there is less than a one percent chance of exceeding 5 cm of fault displacement beneath 
surface facilities important to safety during the preclosure period (approximately 
100 years)
? Potential for displacement on faults that intersect underground facilities and 
demonstrate, with a moderate degree of confidence, that there is less than a 10 percent 
chance of exceeding 7 cm of fault displacement in areas of emplaced waste in 100 years, 
considering all faults that may intersect these areas.
Changes and Status.  The objectives of this investigation have not changed since the SCP 
(DOE 1988) was issued.  However, the work scope for this investigation and study has been 
combined with Study 8.3.1.17.3.6 (Probabilistic Seismic Hazard Analysis) under 
Investigation 8.3.1.17.3 (Section 1.14.3).
1.14.3	Provide Information on Vibratory Ground Motion that Could Affect Repository 
Design or Performance (SCP Investigation 8.3.1.17.3)
Background and SCP Plans.  The purposes of this investigation were to develop a 
seismic-design basis for repository facilities that were important to safety and provide other 
information that would facilitate assessment of the adequacy of the seismic-design basis and the 
identification of credible accidents that might be initiated by seismic events and lead to release of 
radioactive materials.  The seismic-design basis will account for both the potential occurrence of 
earthquakes on nearby faults and potential future underground nuclear explosions at the Nevada 
Test Site.  The investigation describes the analyses required to develop the seismic design basis 
for repository facilities important to safety, both surface and underground, and a deterministic 
methodology proposed for evaluation of seismic hazards.  This methodology included 
10,000-year cumulative slip earthquake methodology for establishing earthquake magnitudes for 
use in estimating design ground motions.  As originally proposed in the SCP (DOE 1988), this 
did not include evaluation of fault-displacement hazards.  This investigation included six studies 
developed to accomplish the following:
1.	Study 8.3.1.17.3.1 (relevant earthquake sources):  This study was to:
? Identify and characterize those earthquake sources that were relevant to a 
deterministic seismic hazard analysis of the site including faults with surface 
geologic expression as well as concealed faults
? Identify earthquake sources that could generate severe ground motions at the site
? Characterize 10,000-year cumulative slip earthquakes for each of the relevant 
seismogenic sources identified.
2.	Study 8.3.1.17.3.2 (underground nuclear explosion sources):  This study was to 
characterize the potential future underground nuclear explosions at the Nevada Test 
Site that would result in the most severe ground motions at the repository site.
3.	Study 8.3.1.17.3.3 (ground motion from regional earthquakes and underground nuclear 
explosions):  This study was to select or develop ground-motion models that were 
appropriate for estimating ground motion at the site from regional earthquakes and 
underground nuclear explosions.
4.	Study 8.3.1.17.3.4 (effects of local site geology on surface and subsurface motions):  
This study was to:
? Document systematic effects on surface and subsurface ground motions resulting 
from the local site geology based on instrumental recordings of ground motion at 
the site
? Identify any significant site-wide bias in ground-motion levels as compared with 
average levels for the southern Great Basin
? Develop a calibrated theoretical site-effects model using the wave properties of 
the local geology in extrapolating effects to locations and depths where ground-
motion recordings were not available.
5.	Study 8.3.1.17.3.5 (ground motion at the site from controlling seismic events):  This 
study was to identify the controlling seismic events (underground nuclear explosions 
or 10,000-year cumulative slip earthquakes that would generate the most severe 
ground motions at the site at frequencies of engineering significance) and characterize 
the resulting controlling ground motions generating suites of strong-motion time 
histories and corresponding response spectra that were representative in amplitude, 
frequency content, and duration of site ground motions.
6.		Study 8.3.1.17.3.6 (probabilistic seismic hazards analysis):  This study was to:
? Quantify the probability for experiencing ground motions of varying degrees of 
severity that might result from earthquakes of varying magnitude and distance 
from the site and use these results to constrain required technical judgments in the 
deterministic evaluation of design-basis ground motions, evaluate the adequacy of 
the deterministic results, and help focus efforts to refine those parameters most 
important for the deterministic calculations
? Determine average rates for earthquake recurrence as a function of magnitude for 
the southern Great Basin to a distance of about 100 km from the site and 
apportion those rates onto active faults and subregional seismic source zones
? Estimate the probability of exceeding given ground-motion levels at the site and 
integrate the contributions to that probability from all identified earthquake 
sources that could generate potentially damaging ground motion at the site.
Changes and Status.  The primary objective of the investigation has not changed since the SCP 
(DOE 1988) was issued.  However, significant changes in approach and methodology have 
occurred.  These are summarized below.
1.	In the study of relevant earthquake sources (8.3.1.17.3.1), the 10,000-year cumulative 
slip earthquake approach was been abandoned (see Study Plan 8.3.1.17.3.1, R1) 
because the cumulative slip earthquake approach does not reflect the DOEs updated 
methodology to assess seismic hazards.  It was determined (USGS 1995; Progress 
Report #9, Section 2.2.13.3 [DOE 1994b]) that a probabilistic approach was more 
suitable for evaluating seismic hazards.  Therefore, a probabilistic seismic hazard 
analysis was used for developing the seismic design basis for both ground motion and 
fault displacement.  This methodology is described in two DOE-YMSCO topical 
reports (YMP 1994b; 1996a).  All work identified in the SCP to compile relevant 
earthquake sources for use in the probabilistic seismic hazard analysis has been 
completed (Pezzopane 1996; Pezzopane et al. 1996).
2.	In the study of underground nuclear explosion sources (8.3.1.17.3.2), an assessment of 
potential locations and yields of underground nuclear explosions has been completed 
using available data (Vortman 1980).  There are no further plans to characterize the 
potential future occurrence of underground nuclear explosions because no additional 
underground weapons testing is expected in the foreseeable future as a result of a 1996 
treaty banning testing.
3.	In the study of ground motion from regional earthquakes and underground nuclear 
explosions (8.3.1.17.3.3), selection and development of ground-motion models has 
proceeded largely as described in the SCP (DOE 1988).  Simulations have been 
completed with multiple, numerical ground-motion models using a suite of 
deterministic scenario earthquakes and a new empirical ground-motion attenuation 
model for normal-fault earthquakes was developed using a world-wide data set 
(Abrahamson and Becker 1996).  In addition, a ground-motion attenuation model for 
underground nuclear explosions using site-specific data collected from surface and 
subsurface stations at Yucca Mountain has been completed (Walck 1996; Abrahamson 
and Becker 1996).  Furthermore, as part of Study 8.3.1.17.4.1, foam-rubber models of 
earthquakes were used to gain information on near-field ground motions from 
normal-faulting earthquakes.  An investigation of precariously-balanced rocks (Brune 
and Whitney 1995), also carried out as part of Study 8.3.1.17.4.1, provided constraints 
on the ground motions that have been experienced at Yucca Mountain in the recent 
geologic past.
4.	In the study of effects of local site geology on surface and subsurface motions 
(8.3.1.17.3.4), measurement of ground-motion effects has benefited from recordings 
made near Yucca Mountain of aftershocks of the ML = 5.6 Little Skull Mountain 
earthquake of 1992.  Shallow velocity profiles have been used to derive in situ seismic 
velocities at the potential repository site (Abrahamson and Becker 1996).  As part of 
the probabilistic seismic hazard analyses being conducted in Study 8.3.1.17.3.6, 
studies were done using resonant-column and tensional shear testing to determine the 
dynamic properties (shear modulus and material damping ratio in shear) of rock at the 
Yucca Mountain site.  The study was completed in 1998 and is documented in Stokoe 
et al. (1998).  Additional testing was done in FY 1999 as part of the geotechnical 
investigations for the Waste Handling Building site.  These investigations are 
described in Stokoe (1999).
5.	In the study of ground motion at the site from controlling seismic events (8.3.1.17.3.5), 
the objectives of this study were achieved through the results of the probabilistic 
seismic hazard analyses conducted in Study 8.3.1.17.3.6.  The probabilistic seismic 
hazards analysis (USGS 1998, p. 7-9, Figures 7-15 and 7-16) was de-aggregated to 
identify dominant contributors to the ground motion hazard at the site for reference 
frequencies of ground motion exceedance described in the report (YMP 1996a).  The 
results were then used to determine design basis earthquakes.  Seismic design inputs 
were determined for these design basis events for a surface site and for a site at the 
waste-emplacement level of the potential repository.  As noted in study 8.3.1.17.3.1 in 
item 1 above, the concept of the 10,000-year cumulative slip earthquake was not used.  
In addition to ground motion, this study was expanded to address fault displacement 
input for seismic design.  The DOEs primary approach to faults, however, is to 
configure the potential repository such that faults are avoided where practical.
6.	In the probabilistic seismic hazards analysis (8.3.1.17.3.6), the study was expanded to 
include evaluation of the potential for fault displacement, which originally was to be 
conducted under Study 8.3.1.17.2.1 (faulting potential at the repository).  In addition, 
the 10,000-year cumulative slip earthquake approach was abandoned.  Instead a 
probabilistic seismic hazard analysis was used to develop the seismic design basis for 
both ground motion and fault displacement.  This methodology is described in a 
topical report (YMP 1994b).  As discussed in this report, the preferred methodology 
for seismic hazard analyses includes an elicitation process whereby a panel of experts 
is assembled to interpret the available seismological, geological, geophysical, and 
geotechnical data sets and, through a series of workshops, develop seismic source, 
fault displacement, and ground motion characteristics along with assessments of 
uncertainties, that form the input to ground motion and fault displacement hazard 
calculations.  The probabilistic seismic hazards analysis was completed in FY 1998 
(USGS 1998).
7.	Geotechnical investigations were initiated in FY 2000 to provide additional data 
supporting development of seismic design inputs and foundation recommendations for 
the Waste Handling Building.  The investigations include drilling boreholes, 
excavating test pits, geological and geophysical logging of boreholes, spectral analysis 
of surface wave surveys, and testing of soil and rock sample properties.  Geotechnical 
investigations are expected to be completed in the first quarter of FY 2002.  Preclosure 
seismic design inputs will be developed using the results of the geotechnical 
investigations.
1.14.4	Preclosure Tectonics Data Collection and Analysis (SCP Investigation 8.3.1.17.4)
Background and SCP Plans.  The primary purpose of this investigation was to provide the data 
and analyses required to assess fault displacement (Investigation 8.3.1.17.2) and vibratory 
ground motion (Investigation 8.3.1.17.3) that could affect repository design or performance.  The 
primary investigation focused on the compilation and analysis of information on reported and 
instrumentally recorded earthquakes that have occurred near Yucca Mountain, on collection of 
information concerning the activity of Quaternary faults at Yucca Mountain and in the vicinity, 
on determining the tectonic stress field near Yucca Mountain and on crustal deformation in the 
vicinity of the site.  In addition, the investigation included a study to integrate the information in 
light of proposed tectonic models.
The data are needed to develop the technical basis for fault displacement and ground-motion 
hazards and the preclosure seismic design bases for surface and subsurface facilities.  Testing 
proposed in the SCP (DOE 1988) included a wide range of activities comparable to site-specific 
seismic hazard studies for other critical facilities.  These included collection of fault-specific 
paleoseismic data from trenching, monitoring, and analysis of historical and current seismicity; 
geophysical surveys; downhole and underground measurements of the in situ stress field; 
geodetic leveling; and tectonic modeling.  The limited data collection and analysis that is 
required by Investigation 8.3.1.17.1 (volcanic activity that could impact the repository) was 
performed within that investigation.  This investigation included 12 studies developed to 
accomplish the following:
1.	Study 8.3.1.17.4.1 (historical and current seismicity):  This study was to:
? Compile information on reported and instrumentally recorded earthquakes that 
characterize the earthquake potential near Yucca Mountain
? Compile a record of historical seismic events in the southern Great Basin or 
within 100 km of Yucca Mountain, including type of event, ground-motion 
intensity for potentially damaging earthquakes, and extent and style of faulting
? Monitor current seismicity to provide empirical information on the current 
frequency of earthquakes in the southern Great Basin, characteristics of faulting, 
how seismic wave amplitudes scale with magnitude and attenuate with distance in 
the region, and how ground motions vary with depth and with surface geology in 
the site area
? Evaluate the potential for human activities to significantly perturb the natural 
seismic hazard at the site by inducing seismicity at or near the site.
2.	Study 8.3.1.17.4.2 (location and recency of faulting near prospective surface 
facilities):  This study was to:
?	Identify appropriate trench locations in Midway Valley at proposed locations for 
repository surface facilities that are important to safety through detailed geologic 
mapping and remote sensing studies
?	Conduct exploratory trenching in Midway Valley to investigate possible 
occurrences of late-Quaternary surface-fault rupture in the vicinity of planned 
surface facility locations important to safety and to identify sites without evidence 
of significant late-Quaternary faulting.
3.	Study 8.3.1.17.4.3 (Quaternary faulting within 100 km of Yucca Mountain, including 
the Walker Lane):  This study was to:
? Identify Quaternary faults within 100 km of Yucca Mountain and characterize 
those faults capable of future earthquakes that could impact design or affect 
performance of the waste facility
? Conduct and evaluate deep geophysical surveys in an east-west transect crossing 
the Furnace Creek fault zone, Yucca Mountain, and the Walker Lane to help 
identify and locate potentially significant seismic source zones including possible 
through-going extensions of the Walker Lane and the Furnace Creek fault zone 
and the relation of these features to detachment faults and to Quaternary faults; 
evaluate the postulated incipient rift zone at Crater Flat
? Compare results of seismic-reflection surveys with results of magneto-telluric 
surveys
? Characterize the conductivity structure of the crust in the Yucca Mountain region; 
provide data for analysis to determine if buried magma bodies are present in the 
vicinity of Yucca Mountain
? Characterize the Quaternary and Holocene fault and fracture pattern within 
100 km of the site and relate that pattern to wrench fault systems, including the 
Walker Lane, the Death Valley-Furnace Creek fault zone, and the Mine 
Mountain-Pahranagat shear zone
? Determine whether the Beatty scarp originated through tectonic or fluvial 
processes, the nature of movement along the scarp (if tectonic), and the age of the 
scarp
? Ascertain the amount of post-middle Miocene horizontal rotation of bedrock 
alongside wrench faults and of bedrock suspected to be part of the upper plate 
above subsurface wrench faults
? Evaluate the Cedar Mountain earthquake of 1932 and its relevance to wrench 
tectonics of the Walker Lane and to potential sources of ground shaking and 
rupture within 100 km of the site
? Evaluate the potential for ground shaking associated with future movement along 
the Bare Mountain fault zone, estimate the age of the most recent faulting and the 
recurrence intervals of faulting on the Bare Mountain frontal fault, and determine 
the nature and age of faulting within the fault complex east of the frontal zone
? Evaluate structural domains and characterize the Yucca Mountain region with 
respect to regional patterns of faults and fractures
? Classify the area into sub-areas (domains) containing relatively homogeneous 
fault and lineament populations suggestive of Quaternary faulting
? Map the areal extent of desert varnish coatings
? Identify areas of suspected hydrothermal alteration.
4.	Study 8.3.1.17.4.4 (Quaternary faulting proximal to the site within northeast-trending 
fault zones):  This study was to:
	?	Evaluate the potential for ground motion resulting from future movement on 
Quaternary left-lateral strike-slip faults within northeast-trending fault zones east 
and south of the site-area
?	Determine the location, spatial orientation, length, width, Quaternary recurrence 
rate, and the location, amount, and nature of Quaternary movement of the Rock 
Valley, Mine Mountain, Stagecoach Road, and Cane Spring fault systems.
5.	Study 8.3.1.17.4.5 (detachment faults at or proximal to Yucca Mountain):  This study 
was to:
? Supply information pertaining to the distribution, displacement rate, and age of 
detachment faults proximal to Yucca Mountain to determine whether they 
represent a significant earthquake source and whether they conceal a significant 
earthquake source at depth
? Evaluate the significance of the Miocene-Paleozoic contact in the Calico Hills 
area to detachment faulting and to determine whether the contact of Miocene 
volcanic rocks on Paleozoic strata is tectonic or depositional
? Evaluate postulated detachment faults in the Beatty-Bare Mountain area and 
determine if they have been active in the Quaternary
? Evaluate the potential relationship of breccia within and south of Crater Flat to 
detachment faulting
? Evaluate postulated detachment faults in the Specter Range and Camp Desert 
Rock areas and determine whether the basal contact of the Horse Spring 
Formation is depositional or tectonic and if movement has occurred in the 
Quaternary
? Evaluate the age of detachment faults using radiometric ages.
6.	Study 8.3.1.17.4.6 (Quaternary faulting within the site area):  This study was to:
? Identify and characterize Quaternary faults that intersect or project toward the 
surface facility, the repository, or the controlled area and determine the potential 
for future earthquakes that could impact design or affect performance of the waste 
facility
? Synthesize data pertaining to the location, spatial orientation, length, width, 
Quaternary recurrence rate, and the location, amount, and nature of Quaternary 
movement of faults within the site area
? Identify hitherto unrecognized Quaternary faults
? Evaluate age and recurrence of movement on suspected and known Quaternary 
faults including the Paintbrush Canyon, Solitario Canyon, Windy Wash, Ghost 
Dance, and Bow Ridge faults.
7.	Study 8.3.1.17.4.7 (subsurface geometry and concealed extensions of Quaternary 
faults at Yucca Mountain):  This study was to evaluate the subsurface geometry and 
concealed extensions of Quaternary faults at Yucca Mountain using the following 
methods:  intermediate seismic refraction and reflection, detailed gravity surveys, 
detailed aeromagnetic surveys, ground magnetic surveys, surface geoelectric surveys, 
gamma-ray measurements, thermal infrared surveys, and shallow seismic-reflection 
(mini-sosie) methods.
8.	Study 8.3.1.17.4.8 (stress field within and proximal to the site area):  This study was 
to:
? Provide data on the ambient stress field at the site and its immediate vicinity that 
will aid in evaluating future movement on faults, stability of potential pathways 
for radionuclide travel controlled by or related to fracture aperture, stability of 
mined excavations, response of the rock mass to thermal loading, and 
applicability of tectonic models
? Measure vertical and lateral variations of in situ stress at the site including in the 
vicinity of the steep hydraulic gradient, at the postulated detachment fault, and in 
subjacent Paleozoic rocks below Yucca Mountain
? Evaluate and test shallow borehole hydrofracture and triaxial strain recovery 
methods for the determination of in situ stress
? Evaluate published and unpublished data on paleostress orientation at and 
proximal to the site and assess the relevance of these data to Quaternary tectonics
? Evaluate theoretical stress distributions associated with potential tectonic settings 
of Yucca Mountain including wrench-fault, normal-fault, and detachment-fault 
tectonic models
? Evaluate the degree to which in situ stress data constrain applicability of these 
tectonic models to neotectonics of the site
? Evaluate the potential relation between fracture aperture and in situ stress.
9.	Study 8.3.1.17.4.9 (tectonic geomorphology of the Yucca Mountain region):  This 
study was to:
? Conduct studies of tectonic geomorphology in the Yucca Mountain region to 
document the magnitude of Quaternary uplift and subsidence and to evaluate 
regional variation in the nature and intensity of Quaternary faulting
? Evaluate the age and areal distribution of surfaces that appear to have been 
tectonically stable at and near Yucca Mountain through studies of desert varnish
? Evaluate extent of areas of Quaternary uplift and subsidence at and near Yucca 
Mountain through evaluation of fluvial fans in the Amargosa Desert, Crater Flat, 
Fortymile Wash, Rock Valley, and Ash Meadows
? Evaluate variations in the nature and intensity of Quaternary faulting within 
100 km of Yucca Mountain through morphometric and morphologic analysis.
10.	Study 8.3.1.17.4.10 (geodetic leveling):  This study was to: 
?	Conduct geodetic re-leveling of base stations and benchmarks to evaluate possible 
historical and contemporary vertical displacements across potentially significant 
Quaternary faults within 100 km of Yucca Mountain and to characterize the 
historical rate of uplift and subsidence
?	Survey selected base stations near Yucca Mountain using global positioning 
satellites.
11.	Study 8.3.1.17.4.11 (characterization of regional lateral crustal movement):  This study 
was to evaluate rates and orientations of historical and current lateral crustal 
movement in the Basin and Range province and the Yucca Mountain region using 
analyses of existing data on seismicity, historical fault offset, and creep.
12.	Study 8.3.1.17.4.12 (tectonic models and synthesis):  This study was to:
? Conduct tectonic modeling and synthesis to evaluate all data relevant to tectonics 
at Yucca Mountain
? Develop a model or range of models that establishes the causal relation between 
application of tectonic forces and formation of structures (wrench, detachment, 
normal, and left-lateral strike-slip faulting, oroclinal bending, etc.) observed at 
Yucca Mountain and vicinity
? Link observed rates of formation of those structures with regional rates of crustal 
strain
? Forecast changes in tectonic setting and the manner in which those changes will 
affect both the regional crustal strain rate and tectonic stability in the Yucca 
Mountain region
? Estimate the effect of those changes on rate and nature of crustal strain at Yucca 
Mountain and vicinity
? Estimate the future rate of tectonic processes at Yucca Mountain and evaluate the 
applicability of this information to geologic hazards at the site
? Evaluate tectonic disruption sequences involving faulting, folding, uplift and 
subsidence, and volcanism that are potentially significant to design or 
performance of the repository.
Changes and Status.  The objectives of this investigation have not changed since the SCP 
(DOE 1988) was issued.  Sufficient data were collected in Investigation 8.3.1.17.4 to form an 
adequate technical basis for proceeding with the seismic hazard analysis.  Results of this 
investigation are summarized in sections 3.13.9 through 3.13.20 of Progress Report #15 
(DOE 1997b) and are described in detail in Whitney (1996).  All studies in the investigation have 
been completed except for monitoring current seismicity (8.3.1.17.4.1) which is continuing.  The 
seismic hazard characterization program has focused on characterizing Quaternary faults at and 
near Yucca Mountain through trench excavation, mapping, and analysis in order to constrain the 
Quaternary history of faulting and earthquakes.  Multiple trenches have been excavated across 
each of the known or suspected Quaternary faults in the site area and on the most active 
Quaternary faults in the region.  Trench interpretations, slip-rate and recurrence analyses, and 
fault-displacement and length analyses are complete.  A catalog of historical earthquakes has 
been prepared (USGS 1998, Appendix G).  Information from monitoring the Little Skull 
Mountain earthquake in 1992 and continuing aftershocks has greatly increased understanding of 
the characteristics of ground motion effects in the vicinity of the site.  In situ stress and 
geodetic-leveling data have been compiled and analyzed.  Alternative tectonic models 
constrained by available geologic mapping and geophysical surveys have been formulated.  
Although the overall objectives of the SCP have been met, some changes in scope and strategy 
have occurred since the SCP was issued.  These changes are summarized below.
1.	In the study of historical and current seismicity (8.3.1.17.4.1), the compilation of 
historical seismic events was expanded to include those events that occurred within a 
300-km radius at the site rather than the originally designated 100-km radius.  This 
modification in scope was in response to discussions with the NRC.  In the monitoring 
of current seismicity, the southern Great Basin seismic network has been upgraded to 
provide more precise information for the Yucca Mountain area.  Whereas the original 
seismic network consisted of 49 analog seismograph stations within a 150-km radius 
of Yucca Mountain, the upgraded network consists of 27 digital stations within a 
50-km radius, 23 of which have been installed (see Section 3.13.9 of Progress 
Report #16, DOE 1997a).  The Southern Great Basin Digital Seismic Network has 
been upgraded to provide more precise location information in an area within 
approximately 60 km of the Yucca Mountain block.  The upgraded network consists of 
29 three-component digitally recorded seismograph stations as compared to the older 
single-component analog recording stations.  The digital network has increased the 
number of earthquakes detected within or near the Yucca Mountain block.  The overall 
threshold in the immediate vicinity of Yucca Mountain is about a magnitude -0.5 
earthquake.  Fourteen analog stations continue to operate in the Death Valley area 
providing important information on the seismicity of that area.  Also in operation are 
19 three-component strong motion stations which are capable of recording the largest 
expected earthquakes in the region.  In the event of a larger magnitude earthquake, 
these stations would provide data important for calculations of ground motions at the 
Yucca Mountain site.
2.	In the study of location and recency of faulting near prospective surface facilities 
(8.3.1.17.4.2), all SCP (DOE 1988) objectives have been achieved without significant 
change in scope.  Faults demonstrating Quaternary activity were identified, but none 
are located in the immediate vicinity of prospective surface facilities or the potential 
repository emplacement areas.  No further work is planned for this study.
3.	In the study of Quaternary faulting within 100 km of Yucca Mountain (8.3.1.17.4.3), 
some of the principal objectives were not met for various reasons, including the work 
was performed in another study; and the expected results would not justify the 
resources needed to obtain the information based on previous results.  The Project 
used an expert elicitation to evaluate the probability and effects of possible seismic 
and tectonic events.  This elicitation used a wide range of data and experience to 
appropriately bound the reasonable range in initiating events and intensities.  These 
bounds were incorporated in analyses of both preclosure and postclosure performance 
assessment.  Significant changes in scope from that outlined in the SCP are as follows:
? Seismic reflection surveys were limited to a 37-km-long traverse extending 
eastward from the east flank of Bare Mountain across Crater Flat to the east side 
of Yucca Mountain (see Progress Report #15, Section 3.3.3, 
Activity 8.3.1.4.2.1.2, DOE 1997b).  No surveys were conducted across the 
Furnace Creek fault zone because of concerns about probable poor data quality 
for deep reflectors and the high cost of the reflection surveys.  The report of the 
Seismic Methods Peer Review Panel (Burns et al. 1991, pp. 1317) recommended 
that a test line be run across Crater Flat and Yucca Mountain.  According to the 
peer review report, the quality of the data collected in this line would form the 
basis for decisions regarding further intermediate and deep reflection profiling.  
DOEs conclusion from the regional seismic line collected in 1994 was that data 
quality in the Tertiary section was adequate to estimate the location and character 
of the Paleozoic-Tertiary contact and concluded that the contact was unlikely to 
be a detachment fault.  However, data for the deeper reflectors were of poor 
quality and suggested that poor data quality would likely result from 
seismic-reflection profiling in other areas.  This conclusion about likely quality of 
the data led to the decision not to undertake seismic profiling for characterizing 
regional seismic sources.  However, geologic field studies were conducted along 
the Death Valley-Furnace Creek fault zone to characterize the style of faulting 
and to determine the history and magnitude of fault displacements along this most 
active of the fault systems in the Yucca Mountain region.  Data resulting from 
these studies are considered adequate for characterizing the paleoseismic history 
along this fault system and for meeting the objectives of the probabilistic seismic 
hazard analysis.  The data were fully evaluated for these purposes by the expert 
panel involved in the probabilistic seismic hazard analysis to determine the 
maximum-magnitude earthquake and recurrence rate for calculating the hazard 
potential of the fault system.
? No new magneto-telluric surveys were made to supplement earlier surveys across 
parts of the Yucca Mountain area.  Although magneto-telluric data can be 
expected to provide certain constraints on crustal structure and composition, final 
interpretations of the data require integration with coincident data from deep 
seismic profiles, teleseismic data, heat-flow and Curie isotherm determinations, 
and gravity measurements.  A cost-benefit analysis resulted in a management 
decision that the personnel requirements and cost of additional magneto-telluric 
surveys were too high when compared with the expected results in terms of 
providing quantitative data that would significantly augment other geological and 
geophysical data sets being used to interpret the Yucca Mountain structure.
? The Cedar Mountain earthquake and its potential as a source for producing future 
ground shaking at the Yucca Mountain site were evaluated in Study 8.3.1.17.3.6 
(probabilistic seismic hazards analysis) as part of the effort involved in 
probabilistic seismic hazards analysis.
? Structural domains and regional patterns of faults and fractures were evaluated as 
part of Study 8.3.1.17.4.12.  The Yucca Mountain area has been classified into ten 
structural domains, each characterized by a structural style that is distinct from 
that of adjacent areas (Day, Dickerson et al. 1998, p. 12).  The structural styles of 
individual domains include both the geometry and intensity of faulting, as well as 
the magnitude and direction of stratal dips.
? Desert-varnish coatings were not mapped as part of Study 8.3.1.17.4.3, but their 
general distribution was provided through the mapping of surficial deposits as 
part of Activity 8.3.1.5.1.4.2 (see Section 3.4.4 of Progress Report #15, 
DOE 1997b).  Desert-varnish coatings on relict colluvial boulder deposits in the 
immediate vicinity of Yucca Mountain also were described in Whitney and 
Harrington (1993, pp. 1008 and 1009, and Figure 2).
? Hydrothermal alteration has not been a subject of study in 8.3.1.17.4.3.  Altered 
rocks in the Calico Hills area were mapped as part of Study 8.3.1.17.4.5, and 
alteration zones are also being described based on outcrop observations and core 
examinations made in Study 8.3.1.4.2.1 (see Section 3.3.3 of Progress Report #16, 
DOE 1997a).
4.	In the study of Quaternary faulting proximal to the site within northeast-trending fault 
zones (8.3.1.17.4.4), all SCP objectives have been met (Whitney 1996), including 
characterization of the Stagecoach Road fault, which was studied as part of 
Study 8.3.1.17.4.6.  No further work is planned for this study.
5.	In the study of detachment faults at or proximal to Yucca Mountain (8.3.1.17.4.5), all 
SCP objectives have been achieved without significant changes in scope.  Importantly, 
the Paleozoic-Tertiary contact appears to be an unconformity rather than an active 
detachment surface (see Section 3.13.13 of Progress Report #16 [DOE 1997a]; 
Brocher et al. 1996).  No further work is planned for this study.
6.	In the study of Quaternary faulting within the site area (8.3.1.17.4.6), all SCP 
objectives have been met, with the Stagecoach Road fault added to the number of 
individual faults that were trenched and mapped in detail.  The study was completed in 
FY 1996; see Progress Report #15 (DOE 1997b), Section 3.13.14 and Whitney and 
Taylor (1996).
7.	In the study of subsurface geometry and concealed extensions of Quaternary faults at 
Yucca Mountain (8.3.1.17.4.7), the SCP objectives were achieved in other site 
characterization studies as discussed in Section 3.13.15 of Progress Report #15 
(DOE 1997b).  Geophysical surveys were performed in Study 8.3.1.4.2.1 (see 
Section 3.3.3 of Progress Report #15), and the data were used to interpret fault 
geometries at depth.  The resulting interpretations were applied in the probabilistic 
analyses of seismic hazards at the potential repository site (Study 8.3.1.17.3.6, 
Section 3.13.8 of Progress Report #16 [DOE 1997a]).
8.	In the study of the stress field within and proximal to the site area (8.3.1.17.4.8), a 
study plan was prepared but has not been finalized.  The work specified in the study 
plan primarily involves measurements of the vertical and lateral variations of in situ 
stress in new boreholes that would have to be drilled in the immediate vicinity of the 
potential repository site.  The drilling of these boreholes, however, was not part of the 
Long-Range Plan (CRWMS M&O 1996a, p. A-6).  Several of the principal objectives 
of the study were met in other studies, most notably in Study 8.3.1.17.4.12, the scope 
of which includes evaluating data on paleostress orientation at and proximal to the site 
and the relevance of these data to Quaternary tectonics, and theoretical stress 
distributions with potential tectonic settings of the site.  Crustal-stress orientations also 
were considered in probabilistic seismic hazard analyses (Study 8.3.1.17.3.6).  Note 
that a large number of publications describe crustal stresses in the southwestern United 
States, including some close to Yucca Mountain (e.g., Stock et al. 1985; Savage 
et al. 1998; Wernicke et al. 1998; and Savage et al. 1999).
9.	In the study of tectonic geomorphology of the Yucca Mountain region (8.3.1.17.4.9), 
the SCP objectives have been met in other studies as discussed in Section 3.13.17 of 
Progress Report #15 (DOE 1997b).  Quaternary deposits were mapped in 
Study 8.3.1.5.1.4 (see Section 3.4.4 of Progress Report #15), with particular emphasis 
given to alluvial fan deposits in Fortymile Wash and their significance for interpreting 
the Quaternary history of the area.  Mapping of Quaternary deposits was completed in 
FY 1996; see Progress Report #15, Section 3.4.4.  Data on the nature and intensity of 
Quaternary faulting within 100 km of Yucca Mountain were collected in 
Studies 8.3.1.17.4.3 and 8.3.1.17.4.6, including the geomorphic expression of features 
marking fault alignments and scarps.  The relevance of using desert-varnish coatings 
for evaluating slope stability in the immediate site area during the Quaternary was 
discussed in Whitney and Harrington (1993, p. 1017).  No further work is planned for 
this study.
10.	In the geodetic-leveling study (8.3.1.17.4.10), all SCP objectives are being met.  In 
addition to monitoring contemporary vertical displacements across Quaternary faults, 
lateral crustal strain is being measured by a regional network of Global Positioning 
System stations and by methods involving very long baseline interferometry.  This 
study of the lateral crustal strain was transferred from Study 8.3.1.17.4.11.  Most of 
the study has been completed, but additional resurveys of level lines and Global 
Positioning System recordings along established traverses are necessary to complete 
the study.  However, the value of additional resurveys is considered minimal based on 
the results of earlier surveys that detected no changes in elevation that could be 
attributed to fault movements at or near Yucca Mountain (Keefer et al. 1996; Savage 
et al. 1994).  The only exceptions to this are elevation changes that occurred in 
response to the 1992 Little Skull Mountain earthquake, the effects of which are well 
documented.
11.	In the characterization of regional lateral crustal movement (8.3.1.17.4.11), the SCP 
objectives were achieved primarily in Study 8.3.1.17.4.10, and the data were applied 
extensively in Study 8.3.1.17.4.12.
12	In the tectonic models and synthesis study (8.3.1.17.4.12), all SCP objectives have 
been met, with the exception of the evaluation of tectonic disruption sequences, which 
are of concern only during the postclosure period.  Therefore, this objective is being 
addressed by ongoing work in Study 8.3.1.8.2.1 where a scenario-development method 
was applied to document all potentially disruptive features, events, and processes as 
part of the TSPA-VA (DOE 1998a, Volume 3, Section 4.4).  For TSPA-SR, a PMR on 
disruptive events was prepared (CRWMS M&O 2000ap).
1.15	ALTERED ZONE CHARACTERIZATION
Altered zone characterization was not included in the SCP (DOE 1988); rather, it was developed 
after the SCP was issued and initiated to provide data on the region in which rock properties 
would be significantly changed because of heat from the waste.  The altered zone 
characterization consists of a single study that includes four activities.  Unlike previous sections, 
this section presents a summary at the study level rather than the investigation level; individual 
activities, however, are not summarized as numbered items.
The altered zone is generally considered to be the volume of rock that surrounds the 
(emplacement drifts) and is defined as that part of the natural system that is likely to experience 
fundamental changes to hydrological, mineralogical, chemical or mechanical characteristics 
because of reactions caused by heating of the repository block from radioactive decay of 
emplaced nuclear waste.  In the altered zone, hydrologic processes are expected to be dominated 
by increased water availability and increased saturation followed by drying in some parts of the 
zone.  The increased moisture content is expected to be produced by vapor condensation at the 
margins of the near-field.  Temperatures in the altered zone are expected to be elevated several 
tens of degrees centigrade relative to ambient conditions.  Geochemical processes are expected to 
be dominated by fluid-rock interactions and reactive transport.  The altered zone is expected to 
be less dynamic than the near-field in that the residence times for water are expected to be longer 
and the dryout zone is not expected to be a dominant feature.  The fluid-rock interactions are 
expected to result in significant coupling between hydrological and geochemical processes, such 
that fluid pathways and geochemical conditions will evolve in a synergistic way.
Generally, the altered zone is considered to be the regions surrounding the emplacement areas 
that maintain temperatures sufficiently low to allow liquid water to exist in pores and fractures.  
This distinction has the advantage of focusing attention on the dominant processes that may 
affect performance in different regions of the repository (e.g., evaporation of water and mineral 
dehydration in the near-field, generally surrounded by a region dominated by water-rock 
interactions, and the kinetics of dissolution and precipitation in the altered zone).
As a result of work reported in the Preliminary Near-Field Environment Report (Wilder 1993) 
which focused on the environmental conditions that directly impact the waste package container 
materials and the waste form, those same processes or interactions were recognized as potential 
causes of significant changes in fundamental properties that could extend for considerable 
distances into the rock mass or natural system.  Therefore, a zone termed the altered zone was 
defined and a study was developed to characterize this region wherein fundamental changes to 
hydrologic, mineralogical, or chemical conditions may take place within the natural system, but 
where these conditions do not interact directly with the waste packages (rather interact with the 
near-field) and where the changes are more significant than in the far-field where ambient 
conditions tend to prevail.  Study Plan 8.3.1.20.1.1, Characterization of the Altered Zone, was 
developed to document this work.
1.15.1	Altered Zone Characterization (SCP Study 8.3.1.20.1.1)
Background and Plans.  The objectives of this study were to: 
? Evaluate the impact of chemical, mineralogical, and mechanical changes on 
hydrological properties and determine the kinetics of the change processes
? Compare computer codes and evaluate their suitabilities for application to altered zone 
evaluations
? Determine parameter values, limits, or ranges needed to define the waste package (near-
field) environment
? Determine, using simulations, the expected response of the altered zone over time.  Four 
activities, described in the lettered items, were included in this study.
Changes and Status.  Study Plan 8.3.1.20.1.1 has been reviewed and revised, and no significant 
changes resulted.  The revised study plan was submitted to DOE.  There is no current funding for 
Altered Zone Characterization Studies.

INTENTIONALLY LEFT BLANK


2.	REPOSITORY PROGRAM (SCP SECTION 8.3.2)
2.1	INTRODUCTION
As envisioned in the SCP (DOE 1988), the repository was to consist of thin-wall waste packages 
that would be emplaced in boreholes drilled in the floors or walls of emplacement drifts.  
However, since the SCP was written, this repository design concept has changed substantially.  
Current plans are to emplace large, robust waste packages covered by drip shields in drifts.  The 
emplacement of waste packages in drifts is expected to have significant performance and cost 
advantages over borehole emplacement.  First, drift emplacement would allow the packages to 
radiate heat to a larger rock area and thus would help control maximum temperatures.  Second, a 
severe seismic event with shear displacements in the repository horizon would be less likely to 
damage drift-emplaced waste containers.  Third, drift emplacement would simplify emplacement 
operations by eliminating the need to drill boreholes and emplace waste packages in them.  
Finally, boreholes appear to have a greater tendency to accumulate groundwater and to confine 
the products of degradation.
The repository design concept in the SCP would have interfaced with the excavations planned 
for the ESF.  However, since the SCP was written, both the repository and ESF concepts have 
changed.  The current repository design is integrated with the drift-based approach under which 
the ESF was actually constructed.  Access to the potential repository is expected to be via a more 
gently sloped ramp than was envisioned in the SCP.  This concept is consistent with the change 
to large waste packages and would allow use of the already completed ESF north ramp.
Another change is that the design is no longer planned to be documented in a license application 
design report.  Instead, the information that it would have contained will be an integral part of 
the license application documentation.
Although repository design has substantially changed from that described in the SCP, most of the 
approaches and types of technical information identified in the SCP to support the design are still 
consistent with the current Program approach.
The status of the repository design activities discussed in the SCP is discussed in more detail in 
the following sections.
2.2	SUMMARY OF CHANGES IN THE REPOSITORY PROGRAM
This section discusses, in order, each section contained in Section 8.3.2 of the SCP (DOE 1988), 
which outlined the repository program.  First, appropriate background is provided and SCP plans 
are given.  Then the changes that have occurred since the SCP was written are discussed and the 
current Project status outlined.  In this discussion, references to sections, tables, and figures are 
to the SCP unless otherwise stated.
Overview of Repository Program (SCP Section 8.3.2.1)
Background and SCP Plans.  This SCP (DOE 1988) section served as the introduction for the 
description of the repository program and introduced the four repository design issues to be 
discussed.  In addition, the section provided details on the interrelationships of the issues, the 
manner in which duplication of effort would be avoided, and the approach to ensuring issue 
resolutions were appropriately integrated.  The second major component of this section was a 
description of the major phases of the repository design from the completed conceptual design 
(described in Section 6 of the SCP) through final procurement and construction design.
Changes and Status.  The issues discussed in this section (and throughout the SCP (DOE 1988) 
are, overall, still applicable, and the program is working toward closing them.  However, the 
designations of the issues and subissues used in the SCP are not generally being used.  For 
example, although Configuration of underground facilities is still a subject being addressed by 
the Program, it is not commonly referred to as Issue 1.11.  The phases of design described in 
this section are still generally applicable.  The design that supported the 1998 Viability 
Assessment (DOE 1998a), though not discussed in the SCP, fits within the period shortly after 
the end of advanced conceptual design and the beginning of license application design.  
Subsequent to the Viability Assessment, some parts of the design were changed by the Project.  
The current design will provide the technical basis for the site recommendation documentation.  
Though not discussed in the SCP, the site recommendation documentation fits within the period 
after advanced conceptual design and close to the beginning of license application design.  There 
will be no license application design report; instead the information that it would contain will be 
an integral part of the license application documentation.  The terms Title I and Title II have 
been dropped from Project use because of the overlapping of meanings between them and the 
work scopes of the design phases.  The names of the design phases are now used to define work 
scopes.  For example, drawings and specifications released for bidding are now referred to as bid 
documents, regardless of how many are released at one time.  Partial releases are no longer 
referred to as bid packages.  Another change is the use of a Management and Operating 
Contractor to develop the design, as opposed to a Systems Engineering Development and 
Management contractor.
2.2.1	Verification or Measurement of Host-Rock Environment (SCP Section 8.3.2.1.1)
Background and SCP Plans.  This section introduced and discussed the development of models 
for the understanding of the site host-rock conditions for three distinct phases:  before excavation 
(pre-waste emplacement environment); after excavation but before waste emplacement 
(post-subsurface excavation environment); and after waste emplacement (post-waste 
emplacement environment).  The section introduced three following subsections, each covering 
one of the above phases.
Changes and Status.  Understanding of the site host rock is still an important part of the 
repository program.  The program is still focused on developing an understanding of the reaction 
of the host rock to both excavation and waste emplacement.
2.2.2	Pre-Waste-Emplacement Environment (SCP Section 8.3.2.1.1.1)
Background and SCP Plans.  This section described 15 activities required to characterize the 
site in its undisturbed, initial condition.  Listed are five additional site data requirements needed 
for seismic evaluations.  The various site programs through which the data would be acquired 
were noted.
Changes and Status.  All items are still applicable to repository design.  Data acquisition in 
these areas continues.  The ESF and related development has provided, and continues to provide, 
much of the information listed.
2.2.3	Post-Subsurface-Excavation Environment (SCP Section 8.3.2.1.1.2)
Background and SCP Plans.  This section described a suite of information to be gathered for 
design of the subsurface openings.  The information required was primarily geared toward 
response of the host rock to the development and continued existence of the subsurface openings.  
Six different activities were listed and described.
Changes and Status.  These data are currently being acquired in various ESF testing and 
monitoring programs.  All data needs are still current with the exception of borehole scale stress 
and deformation.  The change from borehole emplacement to in-drift emplacement was first 
described in Section 4.1.17 of Progress Report #11 (DOE 1995a).  Because emplacement 
boreholes are no longer planned, the data needs associated with them are no longer needed.  A 
plan is being developed for additional testing to obtain sufficient data to support the analyses and 
activities discussed in this section.
2.2.4	Post-Waste-Emplacement Environment (SCP Section 8.3.2.1.1.3)
Background and SCP Plans.  This section discussed information needed to allow 
understanding of the conditions that will exist after heat-producing waste is placed in the 
repository.  Six tasks were listed and described as required to understand the waste heat effects.
Changes and Status.  All information described is still applicable and was  collected as part of 
the ESF single-heater and heated-drift tests.  See discussion related to SCP, Section 8.3.1.15.1 
(DOE 1988).  As discussed above for 8.3.2.1.1.2, information related to borehole emplacement is 
no longer needed.
2.2.5	Coupled Interaction Tests (SCP Section 8.3.2.1.2)
Background and SCP Plans.  This section described the approach planned to address the 
coupled thermal, hydrologic, mechanical, chemical, and radiological phenomena that must be 
considered for design, construction, and performance analyses for the repository.  The section 
included a table that summarizes 40 combinations of coupled processes to be investigated in 
given SCP (DOE 1988) studies or activities.
Changes and Status.  The Projects general approach to investigating coupled site processes is 
consistent with that presented in this section.  The Project is investigating the processes as 
described in Table 8.3.2.1-1 of the SCP (DOE 1988), although some of the specific tests in the 
table have been canceled.  Specifically, there has been no well testing with conservative 
(8.3.1.2.3.1.6) or reactive (8.3.1.2.3.1.7, 8.3.1.2.3.1.8) tracers throughout the site.  The heater 
experiment in unit TSw1 (8.3.1.15.1.6.1), canister-scale heater experiment (8.3.1.15.1.6.2), 
and heated room experiment (8.3.1.15.1.6.5) have not been conducted, but have been replaced 
by a Single Heater Test and Drift Scale Test in the ESF.  These changes have occurred because 
the Project has pursued a more focused suite of tests than those described in the SCP 
(DOE 1988).  In addition, the Single Heater Test and the Drift Scale Test accomplished most of 
the objectives of the tests described in the SCP in a more timely and cost-effective manner.  See 
discussion related to SCP (DOE 1988) Section 8.3.1.15.1.
2.2.6	Design Improvement Activities and Tests (SCP Section 8.3.2.1.3)
Background and SCP Plans.  This section described the planned approach to optimizing 
design.  The section stated that the Project was not seeking an optimum design solution, but 
instead was seeking a design that has been optimized to the point of providing an acceptable 
solution emphasizing certain characteristics.  These characteristics included licenseability and 
simplicity.  The section also provided a table of planned design tradeoff analyses.
Changes and Status.  The approach taken to design optimization to date is consistent with the 
approach described in this section.  The tradeoff analyses in Table 8.3.2.1-2 (DOE 1988) are part 
of the present program, although some of the results are not consistent with the titles of the 
tradeoff studies.  For example, in-drift emplacement is now planned, and because of the change 
in emplacement mode and move to larger waste package designs, waste packages are not 
planned to be transported by hoists.  In addition to the tradeoff analyses shown in this table, the 
program has performed or will perform many other such analyses.  In-drift emplacement was 
prompted by a design concept change to large-capacity waste packages.  The reasons for the shift 
to large, robust waste packages are discussed in the introduction to Section 4 (waste package 
program) of this document.
Emplacement of waste packages in drifts instead of boreholes is expected to have significant 
advantages.  Overall repository excavation costs are expected to be lower because boreholes are 
not necessary.  Drift emplacement would allow the packages to radiate heat to a larger area and 
thus would help control maximum temperatures.  Borehole emplacement of the larger waste 
package would result in violation of both the peak rock temperature goal (200?C) and the fuel 
cladding temperature goal (350?C).  A severe seismic event with shear displacements in the 
repository horizon would be less likely to damage drift-emplaced waste containers than 
borehole-emplaced containers because drift emplacement provides extra clearance between the 
containers and the drift wall.  Drift emplacement would simplify emplacement operations and 
would maintain flexibility of thermal loading because packages could be spaced as needed along 
the drift.  Finally, boreholes appear to have a greater tendency to accumulate groundwater and to 
confine the products of degradation.  This tendency raises concerns about corrosion and 
criticality.  Given that the borehole emplacement approach is no longer being considered, there 
are no activities associated with horizontal versus vertical emplacement borehole orientation nor 
with borehole spacing and length.  Waste packages are to be transported via rail down the gently 
sloping (-2.15 percent) north ramp into the repository.  Thus, there are no activities associated 
with hoisting of waste packages.
2.2.7	Repository Modeling (SCP Section 8.3.2.1.4)
Background and SCP Plans.  This section introduced the four following sections on various 
numerical modeling applications.  Sections follow on geomechanical, seismic, ventilation, and 
safety analyses.
Changes and Status.  This introductory material contains no specific information, so status is 
not relevant.  The following discussions of Subsections 8.3.2.1.4.1 through 8.3.2.1.4.4 provide 
status on topics for this SCP (DOE 1988) section.
2.2.8	Geomechanical Analyses (SCP Section 8.3.2.1.4.1)
Background and SCP Plans.  This section described the understanding of geomechanical 
response current at the time the SCP (DOE 1988) was written.  Listed were three types of 
analytical tools planned for providing perspectives on this response.  The section then described 
the understanding of rock mass thermal response and three types of analytical tools planned for 
development to provide perspectives on this response.  Next, the understanding of the combined 
contribution of excavation and thermal effects to rock mass response was described, and two 
methods planned for use in predicting thermomechanical response were mentioned.  Types and 
scales of analyses planned to be considered were also discussed.
Changes and Status.  Current understanding of the processes is consistent with that provided in 
the SCP (DOE 1988).  The analytical tools and analyses described are being used or are planned 
for use.
2.2.9	Seismic Analyses (SCP Section 8.3.2.1.4.2)
Background and SCP Plans.  This section listed five phenomena planned for consideration in 
seismic analyses.
Changes and Status.  The Program is considering the phenomena described in this section in 
seismic analyses performed to date or planned.
2.2.10	Ventilation Analyses (SCP Section 8.3.2.1.4.3)
Background and SCP Plans.  This section provided a general description of the planned 
ventilation analyses and specifically stated that codes for ventilation analyses will be qualified 
for thermal effects.  Two types of planned analyses were also discussed.
Changes and Status.  The program is performing the types of ventilation analyses discussed in 
the section.  The code being used for ventilation network analyses has been qualified.  The code 
does not automatically include thermal effects, but has provision to manually adjust for thermal 
effects.  The Program is working on qualifying another code that incorporates water inflow to the 
drifts during ventilation.  Results of the one-quarter-scale Engineered Barrier System ventilation 
tests are being used in the qualifying process.
2.2.11	Safety Analyses (SCP Section 8.3.2.1.4.4)
Background and SCP Plans.  This section provided a brief statement that safety analyses would 
be conducted in addressing repository design criteria for radiological and nonradiological health 
and safety.  The section stated that codes used for this purpose would be ones that have been 
proven through extensive past use in the nuclear industry.
Changes and Status.  The program is performing analyses consistent with those called for in 
this section.  Codes used for this purpose are proven, nuclear industry codes.
2.3	ISSUE RESOLUTION STRATEGY FOR ISSUE 1.11:  HAVE THE 
CHARACTERISTICS AND CONFIGURATIONS OF THE REPOSITORY AND 
REPOSITORY ENGINEERED BARRIERS BEEN ADEQUATELY ESTABLISHED 
TO (A) SHOW COMPLIANCE WITH THE POSTCLOSURE DESIGN CRITERIA 
OF 10 CFR 60.133 AND (B) PROVIDE INFORMATION FOR THE RESOLUTION 
OF THE PERFORMANCE ISSUES? (SCP SECTION 8.3.2.2)
Background and SCP Plans.  This section of the SCP (DOE 1988) presented the strategy 
planned to address 10 CFR 60.133 and to resolve performance issues.  Figure 8.3.2.2-1a 
provided a detailed flowchart of this approach (DOE 1988).  The regulatory basis as described in 
this section included both 10 CFR 60.133 requirements and 10 CFR 960 guidelines (Subpart C, 
Sections 4-2-3 and 4-2-5).  The section described four functions that the postclosure waste 
disposal system must satisfy:
? Select repository orientation, layout, etc., to contribute to containment and isolation
? Limit water uses and chemical changes during construction
? Limit excavation-induced changes in rock mass permeability
? Design thermal loading taking into account performance objectives and 
thermomechanical response of host rock.
The section then identifies specific processes contributing to each function.  Tables  8.3.2.2-1 
through 8.3.2.2-4 (DOE 1988) provided specific performance measures, goals, and confidence 
levels for addressing these functions, and accompanying text amplifies the tables.  Specific 
design basis statements were made, such as, The present design basis is that the underground 
excavations will be backfilled before repository closure.
Changes and Status.  The current strategy for addressing this issue is generally consistent with 
the strategy presented in this section of the SCP (DOE 1988).  The four major functions 
described in the section are still valid and are being addressed in the current program.  The types 
of performance measures described in the tables are generally being used in the current program.  
Those measures associated with borehole emplacement have been modified or deleted as 
appropriate to reflect the current emplacement concept.  Because of the limited amount of 
blasting planned to be performed (none in the emplacement drifts), the performance measure for 
permeability change has been deleted.  The confidence levels from the tables are being used to 
establish the need for additional testing and results.  Many of the goals have changed as 
knowledge of the mountain has improved and as the emplacement mode has shifted from 
boreholes to horizontal in-drift emplacement.  The major difference in the present design basis 
from that provided in the SCP section is that in-drift emplacement of waste packages has 
replaced borehole emplacement and drip shields will be used.  Emplacement drift backfill was 
not part of the repository design basis documented in the Viability Assessment of a Repository at 
Yucca Mountain (DOE 1998a).  Subsequent to the Viability Assessment, the Project, as part of 
its defense-in-depth approach, added a drip shield above the waste packages and backfill over the 
drip shield (Wilkins and Heath 1999, Enclosure 2, A.7.0 and A.9.0).  However, backfill is no 
longer planned for use in emplacement drifts (CRWMS M&O 2000d, Section 2.1) because it 
causes the temperature to rise after closure.  All other excavations are planned to be backfilled 
before closure.
2.3.1	Information Need 1.11.1:  Site Characterization Information Needed for Design 
(SCP Section 8.3.2.2.1)
Background and SCP Plans.  This section described site characterization information believed 
at the time the SCP (DOE 1988) was written to be necessary to support design.  The section 
describes three products intended to satisfy the information need:  (1) a data requirements list, 
(2) a reference thermal-mechanical stratigraphy, and (3) development of reference 
thermomechanical rock properties.  The stratigraphy was to be based on a three-dimensional 
stratigraphy contained in an interactive graphics information system.  Table 8.3.2.2-5 
(DOE 1988) listed performance parameters, goals, needed versus current confidence, and 
expected values.  The section also described the Interactive Graphics Information System, 
required for the usable area and flexibility evaluation, and listed data required for use in the 
Interactive Graphics Information System.  In addition, products and approaches that are intended 
to be used to organize information to meet the information need were briefly discussed.
Changes and Status.  The three major products described in this section are being developed by 
the program through the following documents:
? The data requirements list is contained in the Repository Design Data Needs report 
([CRWMS M&O 1995c, Tables 2 and 4).
? Before late 1999, the stratigraphy was being built using the LYNX geoscience modeling 
system.  Those results are described in three reports:  Determination of Available 
Volume for Repository Siting (CRWMS M&O 1997g, Section 7.2), Definition of the 
Potential Repository Block (CRWMS M&O 1995d, Section 6) and Definition of 
Repository Block Limits (CRWMS M&O 1994b, Section 10).
? After 1999, the computer modeling system being used for design is the VULCAN 
Software System.  The results of this modeling are presented in Determination of 
Available Repository Siting Volume for the Site Recommendation (CRWMS 
M&O 2000e) and Section 7 of Determination of the Repository Siting Volume (in 
progress).
? Thermomechanical rock properties are contained in the Technical Data Management 
System, a database containing site and engineering data, and in the YMP Reference 
Information Base (YMP 1996b, Section 1.1.3.2).
The Interactive Graphics Information System is in place to support stratigraphy development.  
Thermomechanical rock properties are being entered in the Reference Information Base 
(YMP 1996b) as called for in the section.  The performance measures, goals, and needed 
confidence levels are included in the present program.  The program is consistent with the 
products described in the section text.  As discussed earlier, because waste emplacement in 
boreholes is no longer planned, the emplacement borehole-related information needs are no 
longer relevant.
2.3.1.1	Design Activity 1.11.1.1:  Compile a Comprehensive List of all the Information 
Required from Site Characterization to Resolve this Issue (SCP 
Section 8.3.2.2.1.1)
Background and SCP Plans.  This design activity involved compiling in one place all 
information needed to resolve the issue, including applicable statistical requirements such as 
acceptable error and level of uncertainty.
Changes and Status.  The Repository Design Data Needs report (CRWMS M&O 1995c, 
Tables 2, 3, and 4) summarizes the site data needed for surface and subsurface repository design.  
The report states what data are needed, when they are needed, and the degree of completeness to 
which they are needed for each design phase.  The term completeness is used as a measure of 
the adequacy and sufficiency of data needed for the existing Program Plan schedule and scope.  
This is a subjective approach intended as a general planning guide.  More quantitative ratings 
that measure data confidence by specifying statistical probabilistic limits were not used because 
such a level of detail is more appropriate for the development of test programs.  However, the 
following descriptors for completeness also consider data variability, which can be regarded as a 
qualitative measure of confidence:
? Substantially Complete:  Data at this level are substantially complete and additional 
analysis or collection is not likely to significantly change the results or conclusions.  
Data variability (a combination of measurement uncertainty and inherent randomness), 
for example, spatial distribution, is reasonably defined.
? Bounded:  Realistic bounding values, with upper and lower extremes identified, have 
been established for data at this level.  Data variability is moderately defined.
? Conservative:  Data are sufficient to estimate credible extreme or worst case values, 
conditions, or assumptions.  Data variability is approximately defined.
Data needs listed in SCP Table 8.3.2.2-5 (DOE 1988) were considered during the development 
of the report, and those considered still valid (which includes most of the data needs) were 
incorporated into the report.
2.3.1.2	Design Activity 1.11.1.2:  Determine Adequacy of Existing Site Data (SCP 
Section 8.3.2.2.1.2)
Background and SCP Plans.  This design activity involved determining adequacy of site data 
and determining where additional data are needed, using statistical methods.  The results of these 
determinations would be used to recommend further data be acquired or trade-off studies be 
performed.
Changes and Status.  The Repository Design Data Needs report (CRWMS M&O 1995c, 
Table 4) analyzes the adequacy of site data and, using that analysis, recommends additional data 
needs.  The level of data completeness is estimated for each data need required for the various 
stages of repository design.  The term completeness is used as a measure of the adequacy and 
sufficiency of data needed for the existing Program Plan schedule and scope.  This is a subjective 
approach intended as a general planning guide.  More quantitative ratings that measure data 
confidence by specifying statistical probabilistic limits were not used because such a level of 
detail is more appropriate for the development of test programs.  However, the following 
descriptors for completeness also consider data variability, which can be regarded as a qualitative 
measure of confidence:
? Substantially Complete:  Data at this level are substantially complete and additional 
analysis or collection is not likely to significantly change the results or conclusions.  
Data variability (a combination of measurement uncertainty and inherent randomness), 
for example, spatial distribution, is reasonably defined.
? Bounded:  Realistic bounding values, with upper and lower extremes identified, have 
been established for data at this level.  Data variability is moderately defined.
? Conservative:  Data are sufficient to estimate credible extreme or worst case values, 
conditions, or assumptions.  Data variability is approximately defined.
During the reporting period, a comprehensive inventory of the available data was made.  This 
inventory revealed that for some data needs, additional data for some parameters are needed in 
certain lithostratigraphic units and/or needed to provide greater coverage of the site.  An 
approach to obtain such additional data is being developed.
2.3.1.3	Design Activity 1.11.1.3:  Document Reference Three-Dimensional Thermal/ 
Mechanical Stratigraphy of Yucca Mountain (SCP Section 8.3.2.2.1.3)
Background and SCP Plans.  This design activity stated that topical reports would be produced 
that will describe the three-dimensional stratigraphy of Yucca Mountain, relying on the 
Interactive Graphics Information System and recorded in the Reference Information Base 
(YMP 1996b).
Changes and Status.  Work on this activity reflects the intent of the design activity.  Work 
focuses on two areas, definition of the thermal-mechanical units and development of a three-
dimensional computer model.  Reports have been and are being developed as called for in the 
design activity, including:
? Definition of the Potential Repository Block (CRWMS M&O 1995d, Section 6)
? Definition of Repository Block Limits (CRWMS M&O 1994b, Section 10)
? Determination of Available Volume for Repository Siting (CRWMS M&O 1997g, 
Section 2.2)
? Determination of Available Repository Siting Volume for the Site Recommendation 
(CRWMS M&O 2000e, Section 8)
? Determination of the Repository Siting Volume (in progress).
The computer model is updated as new information is received.  Data are entered into Technical 
Data Management databases to support development of a three-dimensional stratigraphy model.  
The model output, a three-dimensional profile of Yucca Mountain, is also planned to be entered 
in the Reference Information Base (YMP 1996b).  Topical reports are not currently planned on 
this subject.  Instead, this information will be contained in design analyses.
The modeling activity is integrated closely with the three-dimensional geologic study and 
Integrated Site Modeling activity (which uses the Geologic Framework Model) described in the 
discussion of SCP, Section 8.3.1.4.2.3 (DOE 1988), in this document.  Relevant horizons and 
faults from the Geologic Framework Model activity are transferred to the Software System to 
support design.
Though related, the two modeling activities have different content and purpose.  The Integrated 
Site Modeling activity is constructed to be comprehensive to feed all hydrologic, properties, and 
transport models including performance assessment, while the design model provides geometric 
information in a focused geographic area.  The Integrated Site Modeling activity covers 
65 square miles, encompassing the entire conceptual controlled area boundary, while the design 
model is focused on the repository block.  The Integrated Site Modeling activity contains 
36 lithostratigraphic horizons between the land surface and the top of the Paleozoic rock, as 
described by Majer et al. (1996) while the design model extends only to the Calico Hills 
formation and uses a different grouping of the rock units.
2.3.1.4	Design Activity 1.11.1.4:  Preparation of Reference Properties for the Reference 
Information Base (SCP Section 8.3.2.2.1.4)
Background and SCP Plans.  This design activity called for the development of topical reports 
that would give properties and describe how they were determined from field and laboratory 
measurements.  The reports were to be compared with the issue requirements to ensure adequate 
data is available.  Work to be performed in support of this design activity included rock 
characteristics, initial conditions of stress and temperature, geology (stratigraphy and structure), 
and design data.
Changes and Status.  The Project has, through the 1996 draft revised Program Plan 
(DOE 1996a, Section 2.1.3), systematically identified information needed to support licensing.  
The SCP Issue to which this design activity pertains is part of the information base thought to be 
needed when the SCP (DOE 1988) was written.  Now, in light of enhanced understanding of the 
site, the information currently expected to be needed is sometimes different from that described 
in the SCP (DOE 1988).  Therefore, the Project has not attempted to verify that the Reference 
Information Base (YMP 1996b) contains all the information specified in the SCP.  Instead, 
reliance is placed on completion of activities in the Program Plan to ensure the Reference 
Information Base contains sufficient information to support licensing.
2.3.1.5	Application of Results (SCP Section 8.3.2.2.1.5)
Background and SCP Plans.  This design activity reiterated the three products resulting from 
the information need described in SCP, Section 8.3.2.2.1 (DOE 1988).  This section stated that 
the required site data list would guide site characterization testing.  The reference stratigraphy 
had been entered in the Reference Information Base (YMP 1996b) to support design and 
performance analysis.  The reference rock properties would also be incorporated in the Reference 
Information Base for the same purpose.
Changes and Status.  The current program is using the information as called for in the SCP 
section.  Documentation of information is as described previously.
2.3.2	Information Need 1.11.2:  Characteristics of Waste Package Needed for Design of 
the Underground Facility (SCP Section 8.3.2.2.2)
Background and SCP Plans.  This information need identified waste package information 
needed in the Reference Information Base (YMP 1996b) to support design of the repository.  The 
section described four specific waste package characteristics needed to resolve the issue (thermal 
decay, package size, package temperature constraints, and waste inventory).  An integrated list of 
waste package input items was to be provided, and the completeness of the list would be checked 
by reviewing the processes and goals associated with the issue and by identifying interactions 
and predicted response of the site to the design.  Three methods of determining waste package 
temperature information were described.  Use of ORIGEN2 code or a like code was specified.
Changes and Status.  Work is in progress to address all four waste package characteristics 
specified in this information need.  Rather than compiling an integrated list of waste package 
input items, individual items are requested as needed and provided by way of controlled 
documents.  This approach improves responsiveness and integration between disciplines.  The 
values used in design to support the Viability Assessment (DOE 1998a) were listed in the 
Controlled Design Assumptions Document (CRWMS M&O 1998c, Keys 001, 002, 003, 004, 
005; EBDRD 3.7.G.2, 3.7.G.3; RDRD 3.2.3.2.2.A.11.b; DCSS 023, 025, 031).  The current 
values being used are in the Yucca Mountain Site Characterization Project Requirements 
Document (YMP 2001a) (which superseded the Monitored Geologic Repository Requirements 
Document (YMP 1999)), Monitored Geologic Repository Project Description Document 
(CRWMS M&O 1999c), and in various system description documents (CRWMS M&O 2000d, 
2000g, 2000z, 2000aa, and 2000ab).  The appropriate information from the Controlled Design 
Assumptions Document that is needed to support the site recommendation and license application 
has been captured in the Monitored Geologic Repository Project Description Document 
(Curry 2001).  The Controlled Design Assumptions Document has been archived to preserve the 
Viability Assessment status.
ORIGEN2 and other codes are being used as indicated in the information need.  The rationale for 
the information need as stated in the SCP (DOE 1988) is still applicable.  Some of the waste 
package characteristics were enumerated in the Engineered Barrier Design Requirements 
Document (YMP 1994c, Sections 3.2.3.3, 3.7.G.1-6).  However, while that document still exists, 
it is no longer used.  The information now is in the Yucca Mountain Site Characterization 
Project Requirements Document (YMP 2001a) and in various system description documents 
listed previously (see Section 2.3.16, Information Need 4.4.4 (SCP Section8.3.2.5.4)).  Software 
programs contained in the Characterization Database System are further used to develop related 
information.
The documents listed in the SCP (DOE 1988) as providing design information are obsolete.  
A more up-to-date description is given in the Viability Assessment of a Repository at Yucca 
Mountain (DOE 1998a) and the SDDs.  The specific information needed is generally still as 
listed in the SCP, but the following changes have occurred.  Thermal power output is now 
considered to be a function of age, burnup, enrichment, and reactor type for commercial spent 
nuclear fuel.  This information is contained in the LWR Radiological PC Data Base.  Tolerances 
on the various quantities are not being addressed at present but may be addressed in the future.  
In current design efforts, waste package internal temperatures are emphasized more than surface 
temperatures because internal temperatures are considered more restrictive.
References are made in the SCP (DOE 1988) section to emplacement boreholes; for reasons 
described below in the discussion for 8.3.2.2.3.3, emplacement boreholes will not be used 
(CRWMS M&O 1996g, Volume II, Table 4-1 [Key 011]).
2.3.2.1	Design Activity 1.11.2.1:  Compile Waste Package Information Needed for 
Repository Design (SCP Section 8.3.2.2.2.1)
Background and SCP Plans.  This design activity involved determining what waste package 
information was needed for underground facility design, obtaining the data, and documenting it 
in the Repository Design Requirements Document.
Changes and Status.  This design activity was addressed consistent with the intent of the SCP.  
Waste package information needed to support repository design was compiled and published in 
the Controlled Design Assumptions Document (CRWMS M&O 1998c, Keys 001, 002, 003, 004, 
005; EBDRD 3.7.G.2, 3.7.G.3; RDRD 3.2.3.2.2.A.11.b; DCSS 023, 025, 031).  The appropriate 
information from the Controlled Design Assumptions Document that is needed to support the site 
recommendation and license application has been captured in the Monitored Geologic 
Repository Project Description Document (Curry 2001); and that from the EBDRD has been 
captured in the Monitored Geologic Repository Requirements Document (YMP 1999), which has 
been superseded by the Yucca Mountain Site Characterization Project Requirements Document 
(YMP 2001a).  The Controlled Design Assumptions Document and Engineered Barrier Design 
Requirements Document (YMP 1994c) have been archived to preserve the Viability Assessment 
status.  Therefore, the design requirements are prescribed in the Yucca Mountain Site 
Characterization Project Requirements Document (YMP 2001a), Monitored Geologic 
Repository Project Description Document (CRWMS M&O 1999c), and various system 
description documents (CRWMS M&O 2000d, 2000g, 2000z, 2000aa, and 2000ab).  Software 
programs contained in the Characterization Database System are further used to develop related 
information.  Values are updated as necessary to reflect design changes.  (See the discussion of 
Information Need 4.4.4 (SCP Section 8.3.2.5.4) in this document.)
2.3.2.2	Application of Results (SCP Section 8.3.2.2.2.2)
Background and SCP Plans.  This section of the SCP (DOE 1988) stated that waste package 
information resulting from addressing Information Need 1.11.2 would be used in designing the 
underground facility.
Changes and Status.  The Project is meeting the intent of this SCP (DOE 1988) section.  Waste 
package information is being used on an ongoing basis in support of repository design.  
As discussed previously, the borehole emplacement concept is no longer being pursued, and 
waste package information related to this concept is not required.
2.3.3	Information Need 1.11.3:  Design Concepts for Orientation, Geometry, Layout, and 
Depth of the Underground Facility that Contribute to Waste Containment and 
Isolation Including Flexibility to Accommodate Site-Specific Conditions 
(SCP Section 8.3.2.2.3)
Background and SCP Plans.  This section of the SCP (DOE 1988) described approaches 
planned to obtain data for determining orientation, geometry, layout, and depth of the repository.  
Table 8.3.2.2-6 (DOE 1988) listed five products planned to be used to satisfy the information 
need.  Table 8.3.2.2-7 (DOE 1988) described information expected to be required to complete 
the five products with the required level of confidence.  Finally, the section described how each 
product would be developed.
Changes and Status.  The Project has addressed or is addressing all five products discussed in 
this SCP (DOE 1988) section.  One significant difference, discussed further with respect to 
Design Activity 1.11.3.3, is that the Project is no longer considering borehole emplacement, 
because it is not feasible with the large waste packages currently planned for use.  Also, although 
the change to in-drift emplacement was not the direct result of a performance evaluation, 
substantial waste package and repository performance benefits are expected to result from the 
change.  All Table 8.3.2.2-7 (DOE 1988) input items are being obtained, with the exception that 
those related to borehole emplacement have been modified to apply to in-drift emplacement.  
The SCP descriptions of how each product will be developed are current except for the decision 
on vertical or horizontal borehole emplacement orientation, which is no longer relevant.
2.3.3.1	Design Activity 1.11.3.1:  Area Needed Determination (SCP Section 8.3.2.2.3.1)
Background and SCP Plans.  This design activity was to determine the area required for the 
underground facility.
Changes and Status.  This design activity is being addressed in a manner consistent with that 
described, although the proposed layout has changed substantially because of changes in the 
emplacement concept and from other considerations.  The emplacement area required decreased 
somewhat for the Viability Assessment (DOE 1998a) from that expected at the time the SCP 
(DOE 1988) was written, because the planned repository thermal loading had increased.  
Emplacement area required is inversely proportional to the thermal loading.  However, the 
repository thermal loading has decreased for the site recommendation.  The repository design for 
site recommendation was developed for a thermal loading of 56 MTHM/acre (CRWMS M&O 
2000f [was cited in Rev 3]) and is referred to as the higher temperature option.  This is 
approximately the same (51? MTHM/acre) as it was in the SCP (DOE 1988).  However, the 
design for site recommendation can accommodate a variety of lower-temperature operating 
scenarios that correspond to thermal loads as low as about 20 MTHM/acre (DOE 2001a, 
Sections 2.1.5.1 and 2.1.5.2).  Operational parameters that could result in lower repository 
temperatures include increased waste package spacing, forced ventilation, natural ventilation, de-
rated or smaller waste packages, and surface aging of waste (DOE 2001a, Section 2.1.5.2 and 
Table 2-2).  Total area required includes thermal buffers, accesses, and underground support and 
operations areas.
2.3.3.2	Design Activity 1.11.3.2:  Usable Area and Flexibility Evaluation (SCP 
Section 8.3.2.2.3.2)
Background and SCP Plans.  This design activity involved analyzing the structure and 
stratigraphy of Yucca Mountain to identify usable areas and to ensure adequate area was 
characterized, to produce drift layout arrangements, to ensure drift arrangements fit geology and 
structure, and to identify site geologic data requirements.
Changes and Status.  This activity is proceeding as described.  A three-dimensional computer 
model is being used to develop the boundaries of potential repository development.  Results 
using the LYNX system are in CRWMS M&O 1997g, Section 6.1.  More recent results using the 
VULCAN Software System are summarized in Determination of Available Repository Siting 
Volume for the Site Recommendation (CRWMS M&O 2000e, Section 8).  The boundaries being 
developed are generally in agreement with the primary area identified in the SCP (Mansure and 
Ortiz 1984, Figure 3).  Reconfiguration of the repository and use of a higher thermal load for the 
Viability Assessment (DOE 1998a) than planned in the SCP (DOE 1988) allowed all 
70,000 MTU of waste to be placed west of the Ghost Dance fault.  By expanding the repository 
to the north, all 70,000 MTU of waste can be placed west of the Ghost Dance fault for the higher 
temperature option being used for the site recommendation (CRWMS M&O 2000f, Section 6.3 
and Figure 11).  By expanding the repository to the north and south, all of the 70,000 MTU of 
waste can be placed west of the Ghost Dance fault for some of the lower temperature options 
(BSC 2001c, Section 6.1.3 and Figure 11; DOE 2001a, Figure 2-10).  This provides more 
flexibility in emplacement by allowing the potential usable area east of the Ghost Dance fault to 
be reserved for contingencies.  For the remaining lower temperature options, some of the waste 
must also be placed in the lower emplacement block located east of the Ghost Dance fault (DOE 
2001a, Figure 2-10), this reduces the flexibility for contingencies.  The results of these activities, 
however, are not planned to appear in topical reports or be placed in the Reference Information 
Base (YMP 1996b) as discussed in the SCP.  Instead, these results will appear in design 
analyses, technical documents, and drawings.
2.3.3.3	Design Activity 1.11.3.3:  Vertical and Horizontal Emplacement Orientation 
Decision (SCP Section 8.3.2.2.3.3)
Background and SCP Plans.  This design activity was to provide the performance evaluation 
necessary to document the choice of vertical or horizontal emplacement.
Changes and Status.  This design activity is not being addressed as described.  The SCP 
(DOE 1988) contemplated placing relatively small waste packages in vertical or horizontal 
boreholes, which would then be capped and sealed from the emplacement drifts.  One waste 
package was planned for vertical boreholes, and multiple waste packages were planned for 
horizontal boreholes.  The Project has subsequently substantially increased the size of waste 
packages for reasons discussed in the introduction to Section 4 (Waste Package Program) of this 
document.  The increased size of the waste packages made placing them in boreholes 
impractical.  The present emplacement scenario would have waste packages placed directly on 
supports in the center of emplacement drifts.  For the Viability Assessment (DOE 1998a), 
individual supports called pedestals were used; for the current design, pairs of connected 
supports called pallets will be used.  The decision not to use borehole emplacement was not the 
direct result of a performance evaluation.  Rather, it resulted from the change to large waste 
packages coincident with the multi-purpose canister concept.  The Project decided to go to the 
multi-purpose canister concept on the basis of the cost efficiency and better long-term 
performance of producing and emplacing a smaller number of very robust, large capacity 
packages.  Although the current Program approach no longer includes multi-purpose canisters, 
significant benefits are expected to result from the planned in-drift emplacement of large, robust 
waste packages as compared with the borehole emplacement concept described in the SCP 
(Benton 1993).
2.3.3.4	Design Activity 1.11.3.4:  Drainage and Moisture Control Plan (SCP 
Section 8.3.2.2.3.4)
Background and SCP Plans.  This design activity provided postclosure design requirements for 
the layout of the underground facility that would result in limiting the amount of water in contact 
with waste packages to provide a favorable containment and isolation environment.
Changes and Status.  This design activity is being addressed in a manner consistent with that 
described.  The repository on the whole would be sloped such that any water entering the 
repository would be diverted away from the emplacement drifts to the shaft pumps for removal 
to the surface.  The emplacement drifts would be excavated with a flat gradient to allow water 
entering the emplacement drifts to drain directly into the surrounding rock without having to 
drain along the drift for collection in a centralized area.  In addition, there would be a small 
step at the intersection of the emplacement drifts and the emplacement drift turnouts, that 
would make the invert of the emplacement drifts slightly higher than the invert of the access 
drifts.  For the Viability Assessment (DOE 1998a), a high thermal load was expected to keep the 
temperature above boiling for an extended time period and thus would keep liquid-phase water 
from contacting the waste packages.  For the current design reflected in the site recommendation 
documentation, a lower thermal load along with extensive ventilation during preclosure will keep 
rock temperatures below boiling as discussed in 2.3.6.1 (CRWMS M&O 2000d, 2.1.1, 2.1.4, 
2.2.1, 2.3.1).  Liquid water will be prevented from contacting the waste packages by titanium 
drip shields placed above the waste packages.  The drip shields will be designed to not be 
breached by corrosion or rock falls for 10,000 years (CRWMS M&O 2000d, 1.2.1.12, 1.2.1.13, 
1.2.1.14, 1.2.1.18).
2.3.3.5	Design Activity 1.11.3.5:  Criteria for Contingency Plan (SCP Section 8.3.2.2.3.5)
Background and SCP Plans.  This design activity provided criteria for a contingency plan to 
address postclosure performance issues, such as fault standoff and thermal load adjustments.
Changes and Status.  The repository design for the Viability Assessment (DOE 1998a) 
(reconfigured from that shown in the SCP [DOE 1988]) and the use of a higher thermal load than 
planned in the SCP allowed all 70,000 MTU of waste to be placed west of the Ghost Dance fault 
(upper emplacement block) (DOE 1998a, Volume 2, Section 7.1.1).  The same can be 
accomplished for some of the lower thermal loads for the site recommendation by extending the 
repository to the north (CRWMS M&O 2000f, Section 6.3 and Figure 11) and south (BSC 
2001c, Section 6.1.3 and Figure 11; DOE 2001a, Figure 2-10).  Some of the lower temperature 
operating options will require placement in the area east of the Ghost Dance fault (lower 
emplacement block) (DOE 2001a, Figure 2-10).  This concept provides more flexibility in 
emplacement by allowing some or all of the potential usable area east of the Ghost Dance fault 
(lower emplacement block) to be reserved for contingencies.  In addition, the areas north of Drill 
Hole Wash and west of the Solitario Canyon fault are being investigated for possible inclusion 
into the upper repository block.
2.3.3.6	Application of Results (SCP Section 8.3.2.2.3.6)
Background and SCP Plans.  This activity committed to using data from the resolution of 
Information Need 1.11.3 to support repository design.
Changes and Status.  This activity is being addressed in a manner consistent with that provided 
in the SCP section (DOE 1988).
2.3.4	Information Need 1.11.4:  Design Constraints to Limit Water Usage and Potential 
Chemical Changes (SCP Section 8.3.2.2.4)
Background and SCP Plans.  This information need described methods and approaches for 
developing design constraints to limit water usage and potential chemical changes in the 
underground facility.  Two products were identified as needed to address the information need:  
material inventory criteria and water management criteria.  Table 8.3.2.2-9 (DOE 1988) provided 
a list of parameters and information items needed to develop the products.  The section also 
stated that two sets of criteria were necessary; the first was with regard to modification of the 
postclosure geochemical environment of the waste package as a result of preclosure activities, 
and the second was the degree of saturation of the host rock as a result of preclosure activities.  
Finally, some details were provided on how the material inventory criteria and water 
management criteria were to be developed.
Changes and Status.  The program has developed material inventory criteria and water 
management criteria for the ESF.  A similar process will be used to develop such criteria for the 
repository.  The parameters and information called for in Table 8.3.2.2-9 (DOE 1988) are being 
addressed.  The current approach is generally consistent with the discussion provided in the 
section for obtaining the products.  One change is that drilling of emplacement boreholes and 
types of materials in emplacement boreholes does not apply because the emplacement concept is 
changed to drift emplacement.  Another change is that ventilation during the preclosure period 
followed by placement of drip shields over the waste packages (CRWMS M&O 2000d, 1.2.1.13, 
2.1.4) is expected to keep the waste packages dry for as long as 5,000 years.  The previous 
design was to keep the waste packages dry for a period significantly greater than 300 years with 
a high thermal load that caused evaporation.
2.3.4.1	Design Activity 1.11.4.1:  Chemical Changes Resulting from the Use of 
Construction Materials (SCP Section 8.3.2.2.4.1)
Background and SCP Plans.  This design activity involved quantifying chemical changes such 
as changes in pH that result from using a given quantity of construction materials, using the 
approach described in the information need.
Changes and Status.  Chemical changes that may result from introduction of construction 
materials have been quantified using the approach described in the information need.  The 
potential long-term effects of using cementitious materials (concrete and grout), organic 
compounds and additives, and steel members were studied (CRWMS M&O 1998d).  Methods of 
altering the pH of Portland cement were also studied (CRWMS M&O 1998d).  Because of 
uncertainties in the ability to control the pH, use of cementitious materials is now limited to 
grout for rockbolts and the primary ground support in emplacement drifts will consist of either 
steel sets with wire mesh, steel sets with wire mesh and rockbolts, or rockbolts with wire mesh 
instead of precast concrete segments (CRWMS M&O 2000g, 1.2.1.4, 1.2.1.5, 2.4.1, 2.4.2).
2.3.4.2	Design Activity 1.11.4.2:  Material Inventory Criteria (SCP Section 8.3.2.2.4.2)
Background and SCP Plans.  This design activity involved establishing limits on the inventory 
of materials that will be used in construction and operation of the underground facility and limits 
on the amounts of such materials to be left in the postclosure repository.  The design activity 
called for using the approach discussed in the information need in this effort.
Changes and Status.  The program is addressing this design activity in a manner consistent with 
the approach described in the information need.  All tracers, fluids, and materials being used 
underground in the ESF must first be approved by the DOE.  Limits on inventories of various 
construction materials are applied, as stated in the design activity.  Criteria have been written 
specifically for materials used in the ESF, and these are expected to apply to the repository as 
well.  Instrumentation has been installed to provide data for hydrologic and hazardous mineral 
assessment.  This data will be used to determine compatible water use for construction activities.  
Data collection has started and will continue through year 2002.  Specific criteria for the 
repository will be developed as a result of these performance assessment and design studies.
2.3.4.3	Design Activity 1.11.4.3:  Water Management Criteria (SCP Section 8.3.2.2.4.3)
Background and SCP Plans.  This design activity established limits on the amount of water to 
be used for underground facility construction and operation, indicating amounts and locations for 
individual operations and using the approach and obtaining the data described in the information 
need.
Changes and Status.  To date, the problem of water management criteria for repository 
construction has been addressed in only a preliminary manner.  On the basis of the current 
design, however, some changes in emphasis to Section 8.3.2.2.4 relative to water management 
criteria are expected.  The SCP (DOE 1988) identified the use of water for drilling of 
emplacement boreholes as a primary concern.  The current design for in-drift emplacement 
eliminates this specific issue.  Nevertheless, the use of water for construction of repository access 
and emplacement drifts will need to be evaluated to establish the effects of added water on 
potential repository performance.  Appropriate limits on water use based on this evaluation will 
be required so that any adverse effects of added water on potential repository performance are 
controlled to an acceptable level.  Similar work providing criteria for the control of water use 
during site characterization construction and testing activities has been ongoing since FY 1992.  
This work, reported in Section 6.21 of Progress Report #16 (DOE 1997a) and earlier versions of 
the progress report, does not have an SCP reference (although it is responsive to NRC concerns 
in the Site Characterization Analysis (NRC 1989) regarding site impacts during site 
characterization).  Criteria developed for the ECRB Cross Drift can be considered as preliminary 
criteria for repository construction and operations (CRWMS M&O 2000ad; Section 13.3, 
requirements 5(a)-5(g)).
2.3.4.4	Application of Results (SCP Section 8.3.2.2.4.4)
Background and SCP Plans.  This section stated that information obtained for information 
need 1.11.3 would be used as input to advanced conceptual design and license application design 
reports and in the reference postclosure design.  The section stated that the results of this 
information need would be criteria placed on the preclosure design process and inputs to 
performance assessment.
Changes and Status.  Information obtained for this information need has been used as input to 
advanced conceptual design.  It also was used as input to the site recommendation 
documentation and will be used as input in the future in the license application design, but not to 
a license application design report as planned in the SCP (DOE 1988).  There will not be a 
license application design report because the information that it would contain will be an integral 
part of the license application documentation.  This information is also being used in 
performance assessment as appropriate.
2.3.5	Information Need 1.11.5:  Design Constraints to Limit Excavation-Induced 
Changes in Rock Mass Permeability (SCP Section 8.3.2.2.5)
Background and SCP Plans.  This information need provided approaches planned to be used to 
develop design constraints to limit changes in the rock mass permeability.  Processes for limiting 
magnitude and extent of blast-induced permeability, limiting potential for subsidence by limiting 
extraction ratio and drift sizes, and backfilling drifts at decommissioning were identified along 
with their associated performance measures and tentative goals.  The information need was 
planned to be satisfied through completion of two products:  excavation methods criteria and a 
long-term subsidence control strategy.  The section also provided the technical basis for 
addressing the information need and the parameters and input items expected to be obtained.  
Data and other information needed to satisfy the issue were cited in Table 8.3.2.2-11 
(DOE 1988).  Appropriate criteria were to be developed for guiding the repository design using 
information from waste package characteristics and groundwater travel time.  The two products 
that were to be developed to satisfy this issue are described here in some detail:  
(1) Product 1.11.5-1Excavation Methods Criteria discussed the expectation that drifts would 
be constructed using drill and blast methods, including issues of worker safety and health and 
currently available technology.  (2) Product 1.11.5-2Long-Term Subsidence Control Strategy 
discussed the need for usability of access to the repository throughout the operational period, 
which requires prevention of subsidence during this period.  Also discussed is the need to ensure 
that significant postclosure surface subsidence does not lead to the creation of preferred 
pathways for water migration.  The section also discussed the expectation that drift and pillar 
stability analyses would be performed to estimate the extent and magnitude of loosening of the 
rockmass above a backfilled drift.
Changes and Status.  The program is, in general, addressing this information need as discussed 
in the SCP section (DOE 1988).  Excavation methods for the entire repository, with particular 
emphasis on the emplacement drifts, are being evaluated.  The initial studies on excavation 
method were documented in reports (CRWMS M&O 1994c; CRWMS M&O 1994d).  The 
excavation system was further analyzed during FY 1997, and preliminary drawings were 
prepared.  Based on confirmatory studies (Lee, M.Y. 1997), requirements have been developed, 
and equipment and excavation sequence and concepts have been implemented with the particular 
goal of reducing excavation-induced changes in rock mass permeability.  The current analyses 
differ from the SCP material in Table 8.3.2.2-10 and Product 1.11.5-1 (DOE 1988) in that all 
blasting has been eliminated in the emplacement area and from virtually all nonemplacement 
areas by using tunnel boring machines and roadheader type mechanical excavation equipment.  
Mechanical excavation should lead to less impact on the rock mass permeability by eliminating 
blast damage potential.  Studies that documented changes in permeability following mechanical 
excavation of niches were completed (Wang et al. 1998, Chapter 3).  Current plans differ from 
the excavation criteria in Table 8.3.2.2-11 (DOE 1988) because the current horizontal in-drift 
emplacement mode is different from the borehole emplacement and, therefore, no work is being 
performed on borehole design.  Long-term subsidence control strategy is being addressed as 
planned in SCP product 1.11.5-2 listed in Tables 8.3.2.2-10 and -11 (DOE 1988).  Drift and 
pillar stability analyses are being performed using the best available data and appropriate thermal 
load range.  Efforts are being made to minimize the drift sizes while meeting the operational 
criteria.  The extraction ratio is being maintained within the limit used in the Site 
Characterization Plan Conceptual Design Report (SNL 1987, pages 6-33 and 6-34) for vertical 
borehole emplacement.  The analyses are being performed to evaluate the preclosure access 
requirement mentioned for this product, as well as to gauge the extent of disturbance by 
determining the long-term rock mass displacement.
A very preliminary evaluation was performed to evaluate the long-term subsidence potential.  
The parameters and input items listed in Table 8.3.2.2-11 (DOE 1988) are being addressed.  For 
the Viability Assessment (DOE 1998a), backfilling of the emplacement drifts was considered as 
an option to be maintained instead of being considered mandatory.  Subsequently, the Project 
made emplacement drift backfill mandatory (Wilkins and Heath 1999, Enclosure 2, A.7.0), but 
then changed back to backfill being an option to be maintained (CRWMS M&O 2000d, 2.1).  
Drift and pillar stability analyses are being performed with and without the backfill as a 
stabilizing factor.  The design is being developed using the logic of developing requirements and 
criteria and performing conceptual and preliminary design to meet the preliminary requirements 
and develop new requirements.  The process is similar to the one discussed in the SCP 
(DOE 1988) section.
2.3.5.1	Design Activity 1.11.5.1:  Excavation Methods Criteria (SCP Section 8.3.2.2.5.1)
Background and SCP Plans.  This design activity identified constraints to be placed on 
excavation methods because of postclosure performance considerations, using the approach 
identified in the information need.  Table 8.3.2.2-11 (DOE 1988) presented the excavation 
parameters and input required to satisfy this information need for this activity.
Changes and Status.  The program is addressing this design activity in a manner generally 
consistent with that described in the information need.  However, no work is being performed on 
borehole design (indicated in Table 8.3.2.2-11 (DOE 1988), under the column of Parameters 
and input items) because of the change made from borehole to in-drift emplacement.  
Furthermore, the Site Characterization Plan Conceptual Design Report (SNL 1987, 
Sections 3.3.1.1, 4.5.1.1) assumed that emplacement drifts would be excavated by drill-and-blast 
methods because of their short lengths and need for non-circular sections.  This assumption was 
a function of the repository layout at that time.  The repository layout has since been revised so 
that less than one percent of the repository is now expected to be excavated by drill-and-blast.  
Almost all of the repository, including all emplacement drifts, will be excavated by mechanical 
means, approximately 90 percent of which will be by tunnel boring machine and the remainder 
by machines such as a roadheader.  Using a tunnel boring machine is generally considered to 
produce the least possible disturbance to the surrounding rock mass (smallest possible extent of 
the damaged zone).  Tunnel boring machine feasibility has been demonstrated by the excavation 
of over 7,800 m in the ESF and excavation of over 2,650 m of the ECRB Cross Drift tunnel.
2.3.5.2	Design Activity 1.11.5.2:  Long-Term Subsidence Control Strategy (SCP 
Section 8.3.2.2.5.2)
Background and SCP Plans.  This design activity was intended to develop a position regarding 
the potential for postclosure subsidence (and its impact on containment and isolation) and to 
determine whether current goals are adequate to limit potential for subsidence.  The design 
activity would be addressed using the approach described in the information need.  
Table 8.3.2.2-11 (DOE 1988) provides the parameters and input required to satisfy this 
information need.
Changes and Status.  The program has addressed this design activity in a manner generally 
consistent with the approach described in the information need.  Conceptual studies have been 
performed and preliminary analyses are being performed regarding work described in the SCP as 
product 1.11.5-2 (DOE 1988).  The potential for subsidence has been addressed as follows.  The 
current repository layout consists of a series of long parallel emplacement drifts separated by 
long parallel pillars.  The possibility of ground subsidence is essentially eliminated by requiring 
the pillars to be large enough that they would not fail under the estimated stress regime.  
Empirical evidence (Peng 1992, Section 8.1) indicates that pillars will not collapse and surface 
subsidence will not occur if the excavation extraction ratio in the emplacement areas is less 
than 0.50.  The current design criteria require the excavation extraction ratio to be less than 0.30.  
The layout for the Viability Assessment (DOE 1998a) had an excavation extraction ratio of 
about 0.22, but the current layout as reflected in the site recommendation documentation has an 
excavation extraction ratio of about 0.07, which further increases overall stability and 
substantially reduces the possibility of pillar failure.  The difference between the current 
approach and the parameters and input listed in Table 8.3.2.2-11 (DOE 1988) is that the Site 
Characterization Plan Conceptual Design Report (SNL 1987, Pages 8-22) assumed that all 
emplacement drifts would be backfilled.  The current design does not use backfill as a basis for 
design, although it does not preclude backfilling.  If added in the future, backfill would only 
decrease the potential for subsidence compared with a drift without backfill.
2.3.5.3	Application of Results (SCP Section 8.3.2.2.5.3)
Background and SCP Plans.  This activity stated that the products and information developed 
under Information Need 1.11.5 could be used as input to reference postclosure design and as 
criteria for design of the preclosure repository.
Changes and Status.  Information obtained for this information need is being provided to 
preclosure and postclosure design as indicated in this SCP (DOE 1988) section.  The conceptual 
design was used as input to the TSPA, and the current design provided input to the TSPA and is 
reflected in the site recommendation documentation (CRWMS M&O 2000ac).  The 
products 1.11.5-1 and 1.11.5-2 being developed under this information need provide input to the 
preclosure repository design in the areas of drift and pillar sizes, drift configuration and 
orientation, and ground support needs.
2.3.6	Information Need 1.11.6:  Repository Thermal Loading and Predicted Thermal 
and Thermomechanical Response of the Host Rock (SCP Section 8.3.2.2.6)
Background and SCP Plans.  This information need presented the approach to obtaining design 
thermal loading, taking into account performance objectives and thermomechanical response of 
the host rock.  The information need was intended to be satisfied through five products:  
allowable areal power density, borehole spacing strategy, sensitivity studies, strategy for 
containment enhancement, and reference calculations.  The information need would be resolved 
through analyses and information items listed in Tables 8.3.2.2-13 and 8.3.2.2-14 (DOE 1988).  
The section discussed the approaches planned to support development of the products and 
described the three scales of analyses expected to be performed to resolve the information need:  
container-scale, drift-scale, and far-field.
Changes and Status.  The Project generally is following the approach described in the SCP 
(DOE 1988) section to address the information need.  The five products are being obtained, but 
with some changes.  Product 1.11.6-1 - Areal Power Density, expresses repository thermal load 
in terms of areal power density which has units of kilowatt/acre.  Thermal load is currently being 
expressed in terms of MTHM/acre because this quantity is fixed (i.e., not age dependent) for a 
given waste package.  For a given fuel acceptance scenario, the MTHM/acre has an equivalent 
initial kilowatt/acre.  For the Viability Assessment (DOE 1998a), the Project considered basing 
the spacing of waste packages on an equivalent energy density to smooth temperature variations 
resulting from spacings using kilowatt/acre or MTHM/acre.  Two waste packages having the 
same MTHM could have significantly different initial heat outputs (kilowatts), and two waste 
packages having the same initial heat output could have significantly different total heat outputs.  
Equivalent energy density considers the total heat output from a waste package over some period 
of time, such as 1,000 years, and then spaces the waste packages based on total heat output.  For 
the current design, waste packages will be spaced as close as possible (approximately 0.1 m 
separation) along each emplacement drift (line loading).  Line loading also produces a more 
uniform temperature distribution along the emplacement drifts (Wilkins and Heath 1999, 
Enclosure 2, A.8.0).
Product 1.11.6-2Borehole Spacing is not relevant because the emplacement concept has 
changed from boreholes to horizontal-in-drift.  However, the equivalent of borehole spacing for 
in-drift emplacement is waste package and drift spacing, which are being addressed.
Product 1.11.6-4Strategy for Containment Enhancement mentions the goal of keeping the waste 
packages dry by maintaining the temperature above boiling for 300 years.  Under the high 
thermal loading assumed by the project for the Viability Assessment (DOE 1998a), most of the 
repository would be above boiling for substantially longer than 300 years.  Under the current 
thermal loading being assumed by the Project for the higher temperature option for the site 
recommendation, performance is enhanced by keeping the waste packages dry for a long time by 
forced ventilation and by maintaining the drift walls at about the temperature of boiling water 
during postclosure with the pillar centers below boiling to allow water drainage down to the 
water table.  For the lower temperature options for the site recommendation, performance is 
enhanced by eliminating aqueous corrosion by maintaining the waste package surfaces below 
85oC (DOE 2001a, Figure 2-9).  Prior to closure, drip shields will be placed above the waste 
packages to keep dripping water from contacting the waste packages (CRWMS M&O 2000d, 
1.2.1.13, 2.1.4).
Information items described in the tables in this section are being obtained except for 
thermomechanical properties of overburden.  These data are not being obtained because there is 
little thermal effect in the overburden and, therefore, the data are not needed.
The three scales of analyses described in the information need are consistent with the approach 
to such analyses currently being pursued, except that the container-scale analyses do not consider 
borehole liners or the effects of borehole collapse.  However, the equivalent of these, namely 
drift support systems and drift stability, are included in the drift-scale analyses.
2.3.6.1	Design Activity 1.11.6.1:  Thermal Loading for Underground Facility (SCP 
Section 8.3.2.2.6.1)
Background and SCP Plans.  This design activity established allowable thermal loading as a 
function of waste age and burnup.  The section stated that the effort should start with far-field 
calculations and should also consider near-field constraints.  The approach was to be consistent 
with that presented in the information need.
Changes and Status.  The approach to developing a design thermal loading is generally 
consistent with the approach described in the information need, except for a change of units 
(see previous discussion for the information need).  Thermal loading in the SCP (DOE 1988) was 
expressed as the areal power density in units of kilowatt/acre.  Currently, thermal loading is 
expressed in MTHM/acre, which for a given fuel acceptance scenario corresponds to an average 
kilowatt/acre.  The design for the Viability Assessment (DOE 1998a) focused on thermal loads 
of 80100 MTHM/acre, which is higher than the thermal load associated with the SCP repository 
layout.  The site recommendation documentation reflects thermal loads of approximately 
56 MTHM/acre (CRWMS M&O 2000f, Section 6.3.1 [cited in Rev 3]) to 20 MTHM/acre (DOE 
2001a, Table 2-2).  The change from borehole to in-drift waste package emplacement required 
several thermal constraints to be modified or deleted.  More emphasis is currently being placed 
on postclosure performance than was evident in the SCP.  For example, the SCP had a not-to-
exceed borehole wall temperature goal of 275?C, which was deleted in the Controlled Design 
Assumptions Document, Revision 04 (CRWMS M&O 1997h) as recommended by the thermal 
goal reevaluation report (CRWMS M&O 1993, p. 12) because it was redundant to another 
criterion.  In addition, the SCP had a goal to keep the majority of the borehole walls above 
boiling for more than 300 years.  For the Viability Assessment (DOE 1998a), this goal was 
changed in the thermal goal reevaluation report to a goal to maximize the time the waste package 
stays above boiling consistent with the thermal strategy.  Other studies for the Viability 
Assessment evaluated limitations on thermal loads necessary to prevent violation of thermal 
goals (CRWMS M&O 1996h, Section 7).  These goals are not needed for the site 
recommendation documentation, which will be based on lower thermal loads.  The lower 
temperature options within the thermal range of the selected design concepts provide the 
flexibility to adjust emplacement conditions and ventilation design and duration, to keep the rock 
drift wall temperatures below boiling (96?C at the elevation of the potential repository) following 
closure.  For the higher temperature options for site recommendation, the goal is to maintain the 
emplacement drift wall temperature at 96?C or less during normal preclosure operations; 
however, drift wall and surrounding rock temperatures would rise to above-boiling levels after 
closure.  Only a portion of the rock pillar between the drifts would remain at below-boiling 
levels after closure (BSC 2001d, 1.2.1.4).  For the lower temperature options, the goal is to keep 
the waste package surface temperature at approximately 85?C during the postclosure period.  The 
repository design will permit the repository to remain open and mechanically ventilated for 
approximately 125 years so that the ventilation system can remove sufficient heat to keep the 
drift walls below boiling after closure (Cohon 1999).  Keeping the drift wall temperature below 
boiling after closure requires the drift wall temperatures to be below boiling before closure.  The 
design will permit the repository to be closed as early as 50 years and as late as 125 years after 
the start of waste emplacement, with the possibility of closing as long as 300 years after the start 
of emplacement.  The sensitivity of the postclosure performance of the repository system to 
uncertainties associated with coupled, thermally driven processes will be examined for 
preclosure durations of 50 and 125 years (Cohon 1999).  The actual length of the preclosure 
period and the ventilation mode required will depend on the thermal goals chosen.  Thermal 
models will be refined to reduce conservatism that can increase the estimate of the preclosure 
period required for any desired rock temperature.  Design options to increase the efficiency of 
heat removal also will be evaluated (Cohon 1999).  Repository layouts and results of ventilation 
studies to incorporate the above are in CRWMS M&O 2000f; CRWMS M&O 2000h; BSC 
2001c; and DOE 2001a, Sections 2.1.5.1 and 2.1.5.2.
2.3.6.2	Design Activity 1.11.6.2:  Borehole Spacing Strategy (SCP Section 8.3.2.2.6.2)
Background and SCP Plans.  This design activity was intended to establish strategy for 
choosing borehole spacings as a function of waste thermal output such that all near-field 
constraints will be satisfied.  The activity was intended to be addressed using an approach 
consistent with that described in the information need.
Changes and Status.  With the change from borehole to in-drift emplacement, the focus of this 
activity shifted to a waste package and emplacement drift spacing strategy.  Otherwise, the goal 
of this activity remains the same:  develop waste package spacings such that near-field thermal 
goals are not violated and postclosure performance objectives are achieved (CRWMS M&O 
1996g, Volume II, 8.2.3).
2.3.6.3	Design Activity 1.11.6.3:  Sensitivity Studies (SCP Section 8.3.2.2.6.3)
Background and SCP Plans.  This design activity was intended to determine predicted 
repository thermal and thermomechanical response to variations in model input data.  The 
information would be used to evaluate adequacy of data gathered and to ensure goals have been 
met with proper confidence.  The approach intended was described in the information need.
Changes and Status.  The goal of this activity remains unchanged.  Recent work has dealt with 
determining the sensitivity of repository thermal and thermal-mechanical response to the various 
parameters, including thermal loading, waste package spacing, emplacement drift diameter and 
spacing, age of fuel before emplacement, and backfill in emplacement drifts.  This has resulted in 
changes from the design presented in the Viability Assessment (DOE 1998a).  These changes are 
discussed at the appropriate places within this Documentation of Program Change.
2.3.6.4	Design Activity 1.11.6.4:  Strategy for Containment Enhancement (SCP 
Section 8.3.2.2.6.4)
Background and SCP Plans.  This design activity was intended to document how design of the 
underground facility has taken into account containment and keeping the containers dry for 
300 years.  The approach intended was described in the information need.
Changes and Status.  The goal of this activity and the approach to addressing it remain 
unchanged.  For the Viability Assessment (DOE 1998a), which was based on a high thermal 
loading, studies concentrated on the means of maintaining the temperature of as many waste 
packages as possible above boiling for as long as possible (considerably longer than the 
300 years mentioned in the SCP (DOE 1988).  Related studies concluded that increasing the 
waste loading at the edges of the underground facility, as suggested in product 1.11.6-4, would 
have an insignificant effect on repository performance.  Under the current thermal loading being 
assumed by the Project, keeping the waste packages dry for a long time enhances performance.  
However, this is not accomplished by elevated temperatures but by ventilation and later by 
keeping the water from contacting the waste packages by placing drip shields above the waste 
packages (CRWMS M&O 2000d, 1.2.1.13, 2.1.4).  Performance also will be enhanced by use of 
a granular material as ballast within a carbon steel frame invert.  The ideal ballast material would 
have high thermal conductivity and buffer the chemistry of water transporting radionuclides if 
the waste package is breached (BSC 2001d, 1.2.1.10, 2.1.2).
2.3.6.5	Design Activity 1.11.6.5:  Reference Calculations (SCP Section 8.3.2.2.6.5)
Background and SCP Plans.  This design activity provided a consistent set of calculations with 
proper quality assurance of thermal and thermomechanical response of host rock that can be used 
to support performance assessment.  The approach intended was described in the information 
need.
Changes and Status.  The goal of this activity and the approach to addressing it remain 
unchanged.  Current work under this activity is concentrating on thermal modeling of the TSw2 
thermal-mechanical unit for combined excavation, thermal, and seismic loads.
2.3.6.6	Application of Results (SCP Section 8.3.2.2.6.6)
Background and SCP Plans.  This section stated that information obtained for this information 
need would be input to advanced conceptual design and license application design reports, 
documented in the reference postclosure design, and used as criteria for repository design.
Changes and Status.  Information obtained for this information need was provided to the design 
organization for advanced conceptual design and viability assessment and appeared in the Mined 
Geologic Disposal System Advanced Conceptual Design Report (CRWMS M&O 1996g) and 
Viability Assessment (DOE 1998a).  The information was reflected in the Yucca Mountain 
Science and Engineering Report (DOE 2001a) and also will be reflected in the license 
application design and will be documented in the reference postclosure design.  There will be no 
license application design report because the information it would contain will be an integral part 
of the license application documentation.
2.3.7	Information Need 1.11.7:  Reference Postclosure Repository Design (SCP 
Section 8.3.2.2.7)
Background and SCP Plans.  This information need was to be satisfied by development of two 
products:  (1) a reference postclosure design that would help form the basis of performance 
assessment and (2) documentation in the advanced conceptual design and license application 
design reports showing compliance of the postclosure design with 10 CFR 60.133.  The 
information need listed five information items that must be documented as part of the reference 
postclosure design:
? Location, size, shape, and drainage pattern of underground openings
? Anticipated postclosure state of openings
? Location, function, and design of seals
? Criteria for dismantling underground structures and facilities
? Documentation of surface monuments, if any.
Changes and Status.  As part of ongoing design work, the Project is documenting the reference 
postclosure design that will be used in performance assessment.  The design is being documented 
in reports, analyses, and drawings and identified in the configuration management system 
database.  There will be no license application design report used for documenting postclosure 
design because the information it would contain will be an integral part of the license application 
documentation.  The five items described in the information need are being addressed in the 
design, except that the postclosure state of the openings now refers to the emplacement drifts 
instead of the emplacement boreholes.  For the Viability Assessment (DOE 1998a), plans were to 
backfill emplacement drifts only if there was a demonstrated performance need and not just 
because access was no longer needed.  Current plans are to not backfill the emplacement drifts, 
but the option to backfill is to be maintained.  Backfill acts as an insulator and causes the 
temperatures to rise significantly following closure.
2.3.7.1	Design Activity 1.11.7.1:  Reference Postclosure Repository Design (SCP 
Section 8.3.2.2.7.1)
Background and SCP Plans.  This design activity was to be satisfied by establishing what 
information would constitute the reference postclosure design and documenting the information 
in the advanced conceptual design and license application design reports.
Changes and Status.  The goal of this activity remains unchanged.  A list of information needed 
for performance assessment has been prepared.  The design was documented in the Mined 
Geologic Disposal System Advanced Conceptual Design Report (CRWMS M&O 1996g, 
Volume I, Section 4), the Viability Assessment (DOE 1998a), and the Yucca Mountain Science 
and Engineering Report (DOE 2001a), and will be documented for the license application 
design.
2.3.7.2	Design Activity 1.11.7.2:  Documentation of Compliance (SCP 
Section 8.3.2.2.7.2)
Background and SCP Plans.  The objective of this design activity was to document the 
determination of whether the postclosure design complied with the design goals of this issue in 
the advanced conceptual design and license application design reports.
Changes and Status.  The goal of this activity remains unchanged.  Preliminary documentation 
of compliance has been prepared for the design to date, as discussed in the Mined Geologic 
Disposal System Advanced Conceptual Design Report (CRWMS M&O 1996g, Volume I, 
Section 4), the Viability Assessment (DOE 1998a), and in the Yucca Mountain Science and 
Engineering Report (DOE 2001a).  The determination of whether the postclosure design is 
expected to comply with the design goals for this issue will be documented as part of the license 
application design.  However, as explained previously in the discussion of the information need, 
compliance will not be documented in a license application design report.
2.3.7.3	Application of Results (SCP Section 8.3.2.2.7.3)
Background and SCP Plans.  This section stated that the reference design produced to satisfy 
this information need would be placed in the Reference Information Base (YMP 1996b) for use 
as input to performance assessment.
Changes and Status.  The reference design is being documented, but not in the Reference 
Information Base.  Instead, the design is being documented in reports, analyses, and drawings.  
Information being documented as a result of these activities is being used to support assessments 
of repository and waste package performance as specified in this SCP (DOE 1988) section.
2.3.8	Schedule for Configuration of Underground Facilities (SCP Section 8.3.2.2.8)
Background and SCP Plans.  This section provided a schedule for addressing Design 
Activities 1.11.1.1 through 1.11.7.2.
Changes and Status.  The schedule for obtaining information for key activities has been revised 
as described in the semiannual progress reports.  This method of documenting changes is

consistent with the text in the SCP (DOE 1988) section.  The Project has not, however, 
undertaken to ensure that the schedule revisions for all the specific items in Table 8.3.2.2-15 
(DOE 1988) are included in the progress reports.  The schedules presented in the 1988 SCP were 
based on the DOEs June 1987 Mission Plan Amendment (DOE 1987a, Appendix B; 1987b, 
Appendix B), which assumed the license application for the repository would be submitted to the 
NRC in 1995.  In 1989, the Secretary of Energy assessed the progress and needs of the site 
characterization project, and a new schedule was adopted that planned for the submittal of the 
license application in FY 2002.  However, recent modification of the Programs schedule during 
this reporting period, deferred the site recommendation to the President until early 2002, and, 
consequently, deferred the submittal of the license application.  The DOE is currently evaluating 
the schedule for the submittal of the license application to the NRC, if the site is recommended 
and approved.  The evaluation is considering the latest requirements of NRCs proposed 10 CFR 
Part 63 (64 FR 8640), recent interactions with the NRC, and the budgetary constraints from 
Congressional appropriations.
2.3.9	Issue Resolution Strategy for Issue 2.7:  Have the Characteristics and 
Configurations of the Repository Been Adequately Established to (a) Show 
Compliance with the Preclosure Design Criteria of 10 CFR 60.130 Through 60.133 
(see footnote 1, page I-1) and (b) Provide Information for the Resolution of the 
Performance Issues? (SCP Section 8.3.2.3)
Background and SCP Plans.  This section stated that the issue is concerned with the features of 
the repository that relate to radiological safety.  Figure 8.3.2.3-1 (DOE 1988) showed the 
relationship of this issue to other issues and to the site characterization program.  The section 
described the proposed licensing strategy for resolving the issue, including a logic diagram 
(DOE 1988, Figure 8.3.2.3-2a).  The section also identified functional requirements and 
discussed performance allocation.  Table 8.3.2.3-2 (DOE 1988) listed subfunctions in support of 
the functional goals, along with processes, performance measures, tentative goals, and 
confidence levels needed for each subfunction.  Table 8.3.2.3-3 (DOE 1988) listed various 
parameters required for resolution of the issue.  The text describes the approach to testing to 
ensure all goals are met including verifying that the as-low-as-reasonably-achievable principle 
had been met.  Finally, the section describes how the information needs to address the issue 
would be approached and how they related to each other.
Changes and Status.  The issue resolution strategy for this issue being pursued by the Project is 
consistent with that presented in this section (including the licensing strategy section).  
Performance allocation is being addressed as part of the functional analysis process.  Results are 
summarized in the Viability Assessment (DOE 1998a, Volume 2, Section 3.3).  The logic 
diagram in Figure 8.3.2.3-2a (DOE 1988) is consistent with the current Program.  Subfunctions 
in Table 8.3.2.3-2 and parameters in Table 8.3.2.3-3 (DOE 1988) are being addressed in 
requirements documents and subsequently in design.  Table 8.3.2.3-3 and the text referred to 
30 CFR Chapter I, Subchapters D, E, and N.  The source for the statement was 
10 CFR 60.131(b)(9) but a revision of 10 CFR 60 moved the cited text to 10 CFR 60.131(j).  
Since that part of 10 CFR 60 was written, 30 CFR Chapter I has been reorganized and 
Subchapters D and E were eliminated as headings.  The parts of 30 CFR that were in 
Subchapters D and E are now parts 18-29, 31-33, and 35-36 of Subchapter B.

The current approach to testing is consistent with the approach discussed in the SCP (DOE 1988) 
section.  The current approach to addressing the information needs is consistent with the 
approach described in this section, except that, as noted previously, the design configuration 
information and results will not be placed into, or obtained from, the Reference 
Information Base.
Environmental data specified in Table 8.3.2.3-3 (DOE 1988) are being collected as follows.  The 
eight meteorological parameters (wind speed, wind direction, atmospheric stability, mixing layer 
depth, average ambient temperature, atmospheric moisture, precipitation, and barometric 
pressure) are being monitored two ways.  Except for mixing layer depth, the parameters are 
being monitored locally (within about 20 km) using a nine-station network in the vicinity of 
Yucca Mountain.  This activity is discussed further in Section 1.9.2 of this document.  All the 
parameters are included in the Scientific Investigation Implementation Package for Regional 
Meteorology (CRWMS M&O 1995b), the scope of which includes the 80-km radius of Yucca 
Mountain described in the SCP (DOE 1988).  The nine station meteorological monitoring 
network previously described, was reduced in scope in July 1999, although the nine stations 
remain active for precipitation, air temperature, and humidity measurements.  Four of the stations 
still measure airflow, atmospheric stability indicators, barometric pressure, and solar radiation; 
three additional ridge-top precipitation stations were also kept active.  The present network is 
described in Appendix A of the Technical Work Plan for:  Meteorological Monitoring and Data 
Analysis (CRWMS M&O, 2000ae).  To date, recreational use of water bodies has not been 
examined but may be considered as part of the development of the repository license application.  
The Project is monitoring surface water runoff but so far has not emphasized a goal for surface 
water runoff to surface water bodies.
2.3.9.1	Information Need 2.7.1:  Determination that the Design Criteria in 
10 CFR 60.131 Through 60.133 and Any Appropriate Additional Design 
Objectives Pertaining to Radiological Protection Have Been Met (SCP 
Section 8.3.2.3.1)
Background and SCP Plans.  This information need stated that three site parameters were 
required:  concentrations of naturally occurring radon and its daughters in repository airstreams, 
use of shielding properties of host rock, and quantification of transport of radioactive materials to 
workers and the public.  A list of site data required was provided and the logic process for 
addressing the information need was described.
Changes and Status.  The parameters and data listed in the information need are being obtained.  
The current logic process to meeting the information need is consistent with that discussed in the 
SCP (DOE 1988) section (see footnote 1, page I-1).
2.3.9.1.1	Design Activity 2.7.1.1:  Design Evaluation for Compliance with Radiological 
Safety Design Criteria and Performance Goals (SCP Section 8.3.2.3.1.1)
Background and SCP Plans.  This design activity evaluated the repository design against 
radiological safety design criteria and performance goals.  Parameters to be used were those 
listed in the information need.  The activity was intended to consist of a complete radiological 
safety design analysis and performance goal assessment of the reference repository design, 
operating plan, and supporting analyses at each phase of design.
Changes and Status.  As stated in the previous discussion for the information need, the 
parameters listed therein are being addressed subject to changes noted in the discussion of the 
issue resolution strategy for Issue 2.7.  A performance assessment and preliminary MGR hazards 
analysis were performed for and documented in the Mined Geologic Disposal System Advanced 
Conceptual Design Report (CRWMS M&O 1996g, Volume I Section 4 and Volume IV 
Section 10) and in the Viability Assessment (DOE 1998a, Volume 2, Section 2, and Volume 3).  
Safety analyses and additional performance assessments in conjunction with design work are 
reflected in the Yucca Mountain Science and Engineering Report (DOE 2001a, Section 4).  It 
will also be reflected in the license application.
The SCP (DOE 1988) outlined a comprehensive design for radiological controls, many of which 
have only been considered conceptually for the repository.  Specifically, these include monitors 
and controls that limit the dispersion of radioactive contamination in and from the repository, 
radiation alarms for airborne radiation, alarms for explosion and fire detection, and 
instrumentation and control systems for other safety-related repository features.  These 
instrumentation requirements have been considered.  No impediments are forecast for eventual 
design and implementation based on currently expected repository conditions.  Some analyses to 
determine the radiological environmental conditions related to such designs have been completed 
(CRWMS M&O 1997i, Section 7 and 8; CRWMS M&O 1997j, Sections 7 and 8; and BSC 
2001f).  The most recent of these analyses provides a technical basis for recommending limiting 
values of radioactive contamination on the external surfaces of waste packages to be accepted 
into the subsurface repository.  It also provides an evaluation of the extent of potential releases 
from a defective waste package and the detectability of the released contents.  Additional 
analyses are planned.  Detailed design may proceed during subsequent fiscal year efforts using 
these results.
Structures, systems, and components important to safety are evaluated as part of the ongoing 
Q-List (YMP 2001b) activity.  A Q-List reflecting major repository design changes was issued in 
March 1998.  A preliminary classification analysis of repository items (CRWMS M&O 1998f) 
issued in November 1998 updated the Q-classifications to agree with the Viability Assessment 
(DOE 1998a).  The preliminary classification analysis was used in lieu of the Q-List 
(YMP 1998a) until it was superseded in August 1999 by individual classification analyses 
performed for each system.  The results of individual classification analyses have been 
incorporated into Revision 7 of the Q-List (YMP 2001b).  The as-low-as-reasonably-achievable 
principle is being implemented in the design process.
Additionally, revisions to the regulations prescribing the radiation dose limits for both workers 
and the general public from a repository at Yucca Mountain have been proposed by the NRC at 
10 CFR 63 (64 FR 8640) and the U.S. Environmental Protection Agency (EPA) at 40 CFR 197 
(64 FR 46976).  Finalization of these regulations may cause significant changes to the program 
as envisioned in the SCP (DOE 1988).

2.3.9.1.2	Application of Results (SCP Section 8.3.2.3.1.2)
Background and SCP Plans.  This section stated that information for this information need 
would be used in preclosure design and technical feasibility studies to demonstrate compliance 
with radiological safety design criteria and performance goals.
Changes and Status.  Information obtained for this information need is being used in a manner 
consistent with that specified in this SCP (DOE 1988) section.
2.3.10	Information Needs 2.7.2 and 2.7.3:  (1) Determination that the Design Criteria in 
10 CFR 60.131 Through 60.133 and Any Appropriate Additional Design Objectives 
Pertaining to the Design and Protection of Structures, Systems, and Components 
Important to Safety Have Been Met, and (2) Determination That the Design 
Criteria in 10 CFR 60.131 Through 60.133 and Any Appropriate Additional Design 
Objectives Pertaining to Criticality Control Have Been Met (SCP Section 8.3.2.3.2)
Background and SCP Plans.  This information need listed site parameters required to address 
the need and provided a basic logic for addressing it.
Changes and Status.  The Project is addressing this information need in a manner consistent 
with this section.  The site parameters listed in the information need are being addressed (see 
footnote 1, page I-1).
2.3.10.1	Application of Results (SCP Section 8.3.2.3.2.1)
Background and SCP Plans.  This section stated that information obtained for this information 
need would be used directly to demonstrate compliance with radiological safety design criteria 
and performance goals.
Changes and Status.  The Project is addressing this information need in a manner consistent 
with this section of the SCP.
2.3.10.2	Schedule for Repository Design Criteria for Radiological Design (SCP 
Section 8.3.2.3.3)
Background and SCP Plans.  This section of the SCP (DOE 1988) provided a schedule for 
addressing Design Activity 2.7.1.1.
Changes and Status.  The schedule for obtaining information for key activities has been revised 
as described in the semiannual progress reports.  This method of documenting changes is 
consistent with the text in the SCP section.  The schedules presented in the 1988 SCP were based 
on the DOEs June 1987 Mission Plan Amendment (DOE 1987a, Appendix B; 1987b, 
Appendix B), which assumed the license application for the repository would be submitted to the 
NRC in 1995. In 1989, the Secretary of Energy assessed the progress and needs of the site 
characterization project, and a new schedule was adopted that planned for the submittal of the 
license application in FY 2002.  However, recent modification of the Programs schedule during 
this reporting period, deferred the site recommendation to the President until early 2002, and, 
consequently, deferred the submittal of the license application.  The DOE is currently evaluating

the schedule for the submittal of the license application to the NRC, if the site is recommended 
and approved.  The evaluation is considering the latest requirements of NRCs proposed 10 CFR 
Part 63 (64 FR 8640), recent interactions with the NRC, and the budgetary constraints from 
Congressional appropriations.
2.3.11	Issue Resolution Strategy for Issue 4.2:  Are the Repository Design and Operating 
Procedures Developed to Ensure Nonradiological Health and Safety of Workers 
and Adequately Established for the Resolution of the Performance Issues? (SCP 
Section 8.3.2.4)
Background and SCP Plans.  This section stated that the issue is concerned with the features of 
the repository that relate to mining (nonradiological) worker safety.  Designs and procedures for 
the repository were to address at least 12 factors listed in the section.  The section also discussed 
major factors affecting worker safety and included certain assumptions regarding whether 
several potential events or accidents should be of concern.  A five-step approach to resolving the 
issue was presented in the text and graphically depicted in Figure 8.3.2.4-1a (DOE 1988).  The 
text also listed system subelements that do and do not require site data.  Tables 8.3.2.4-1 
through 8.3.2.4-9 (DOE 1988) provided specific functions, processes performed, performance 
measures, goals, and needed confidence for achieving the goals.
Changes and Status.  The issue resolution strategy for this issue being pursued is consistent 
with that presented in this section and the logic diagram in Figure 8.3.2.4-1a (DOE 1988).  The 
12 factors listed in the section are being addressed.  The system subelement for borehole 
emplacement has been deleted.  The functions and performance measures in Tables 8.3.2.4-1 
through 8.3.2.4-9 (DOE 1988) are being addressed, but some of the tentative goals have been 
modified or deleted to be consistent with the change in the basic repository emplacement concept 
and other design changes.  For the Viability Assessment (DOE 1998a), these goals dealt with 
limiting rock damage caused by blasting (little or no blasting will now occur) (DOE 1998a, 
Volume 2, Section 4.2.1), rockfall criteria (addressed by a robust full-circle type lining) 
(DOE 1998a, Volume 2, Section 4.2.2.2), air cooling power (now incorporated by specifying 
other ventilation parameters) (CRWMS M&O 1998c, DCSS 019), and duration of drift stability 
(about 150 years, including a retrieval operation period, instead of 100 years) (DOE 1998a, 
Volume 2, Section 4.2.2.2).  Rockfall criteria as reflected in the site recommendation 
documentation are being addressed in emplacement drifts by a full circle-type support consisting 
of either steel sets with wire mesh, steel sets with wire mesh and rockbolts, or rockbolts with 
wire mesh (BSC 2001e, 1.2.1.4, 1.2.1.5, 2.4.1, 2.4.2), and a full-circle concrete lining in 
accesses.  Also, the duration of required drift stability can vary from 50 to 300 years (BSC 
2001e, 1.2.2.2.2; BSC 2001d, 1.2.1.5, 2.2.1) (Cohon 1999, Item 2, p. 7 of enclosure).  The 
current approach to addressing the information needs is consistent with the approach described in 
this section.
2.3.11.1	Information Need 4.2.1:  Site and Performance Assessment Information Needed 
for Design (SCP Section 8.3.2.4.1)
Background and SCP Plans.  This information need required that information needed to 
implement design and operating procedures be identified.  The proposed two-part approach to 
doing this involved (1) addressing the issue of developing and documenting the design and

procedures and (2) identifying information needed to implement those procedures.  The section 
then discussed how each part would be addressed.  Next, specific parameters for the information 
need were identified.  Finally, the logic for obtaining the information was briefly discussed.
Changes and Status.  The current program is using the two-part approach described in the 
information need, including the parameters and logic process that were planned.
2.3.11.1.1	Design Activity to Verify Access and Drift Usability (SCP Section 8.3.2.4.1.1)
Background and SCP Plans.  This design activity described seven demonstrations and tests 
planned in the exploratory shaft facility to demonstrate that design and operating procedures 
were adequate for repository design.
Changes and Status.  This design activity is being conducted essentially as described.  The only 
significant difference is that the emphasis in the SCP (DOE 1988) on blasting studies has not 
occurred because of repository redesign, which will result in less than one percent of the 
repository being excavated by drill-and-blast.  (See the previous discussion for Design 
Activity 1.11.5.1)
2.3.11.1.2	Design Activity to Verify Air Quality and Ventilation (SCP Section 8.3.2.4.1.2)
Background and SCP Plans.  This design activity provided an approach to designing the 
repository ventilation system using four specific parameters.
Changes and Status.  This design activity is being conducted as described in the SCP.
2.3.11.1.3	Application of Results (SCP Section 8.3.2.4.1.3)
Background and SCP Plans.  This section stated that information obtained for the associated 
information need would provide the data base required to assess the adequacy of design and 
operating procedures for worker nonradiological health and safety.
Changes and Status.  The information being obtained is being used as described.
2.3.12	Schedule for Non-Radiological Health and Safety (Issue 4.2) (SCP Section 8.3.2.4.2)
Background and SCP Plans.  This section of the SCP provided a schedule for addressing 
Design Activities 8.3.2.4.1.1 and 8.3.2.4.1.2.
Changes and Status.  The schedule for obtaining information for key activities has been revised 
as described in the semiannual progress reports.  This method of documenting changes is 
consistent with the text in the SCP (DOE 1988) section.  The schedules presented in the 
1988 SCP were based on the DOEs June 1987 Mission Plan Amendment (DOE 1987a, 
Appendix B; 1987b, Appendix B), which assumed the license application for the repository 
would be submitted to the NRC in 1995.  In 1989, the Secretary of Energy assessed the progress 
and needs of the site characterization project, and a new schedule was adopted that planned for 
the submittal of the license application in FY 2002.  However, recent modification of the 
Programs schedule during this reporting period, deferred the site recommendation to the

President until early 2002, and, consequently, deferred the submittal of the license application.  
The DOE is currently evaluating the schedule for the submittal of the license application to the 
NRC, if the site is recommended and approved.  The evaluation is considering the latest 
requirements of NRCs proposed 10 CFR Part 63 (64 FR 8640), recent interactions with the 
NRC, and the budgetary constraints from Congressional appropriations.
2.3.13	Issue Resolution Strategy for Issue 4.4:  Are the Technologies of Repository 
Construction, Operation, Closure, and Decommissioning Adequately Established 
for the Resolution of the Performance Issues? (SCP Section 8.3.2.5)
Background and SCP Plans.  This section stated that the issue was concerned with determining 
whether the repository can be designed, constructed, operated, and closed using reasonably 
available and proven technology.  A five-step approach to resolving the issue was presented in 
the text and graphically depicted in Figure 8.3.2.5-1a (DOE 1988).  Tables 8.3.2.5-1 through 
8.3.2.5-12 (DOE 1988) provided specific functions, processes performed, performance measures, 
goals, and needed confidence for achieving the goals for 12 system elements.  Finally, the 
section provided a list of five criteria planned to support the assessment that the technology is 
reasonably available.
Changes and Status.  The issue resolution strategy for this issue being pursued and the logic 
diagram in Figure 8.3.2.5-1 (DOE 1988) is consistent with the current Program.  The SCP 
(DOE 1988) text states that system elements not requiring site-specific data are not discussed 
further in the SCP, but will be addressed in a repository design plan.  There will be no repository 
design plan.  Instead, these elements will be addressed in design analyses and system design 
description documents (see the following discussion below for Information Need 4.4.4).  The 
performance measures and parameters in Tables 8.3.2.5-1 through 8.3.2.5-12 (DOE 1988) are 
being addressed as part of ongoing design and site characterization except for those in 
Tables 8.3.2.5-5 and 8.3.2.5-10 (DOE 1988) that deal with borehole emplacement, which is no 
longer part of the repository design.  Some of the tentative goals and expected values have been 
modified or deleted to be consistent with the change in the basic repository emplacement concept 
and other design changes.  These goals deal with limiting rock damage caused by blasting (little 
or no blasting will now occur), rockfall criteria (being addressed by a full-circle type support), 
air cooling power (now incorporated by specifying other ventilation parameters), and duration of 
drift stability (now as long as 300 years, including a retrieval operation period, instead of 
100 years).  The five criteria planned in the SCP for use in supporting the assessment are 
consistent with the current program approach.
2.3.13.1	Information Need 4.4.1:  Site and Performance Assessment Information Needed 
for Design (SCP Section 8.3.2.5.1)
Background and SCP Plans.  This information need summarized the site-related parameters 
identified as being required by the remaining information needs under Issue 4.4.  The section 
provides four observations in support of the technical basis for the information need and refers to 
the parameters in Tables 8.3.2.5-1 through 8.3.2.5-12 (DOE 1988) for use in addressing the 
information need.  The section then provides a justification for selecting these parameters.

Changes and Status.  The four observations in the information need are still considered valid. 
Exceptions stated in the preceding discussion for Issue 4.4 to the parameters in Tables 8.3.2.5-1 
through 8.3.2.5-12 (DOE 1988) apply.  The current program is consistent with the logic 
presented in the information need.
2.3.13.1.1	Application of Results (SCP Section 8.3.2.5.1.1)
Background and SCP Plans.  This section stated that the information obtained to address the 
associated information need would be used to address Issue 4.4 by providing information needed 
in Information Needs 4.4.2 through 4.4.10 to update the Reference Information Base 
(YMP 1996b) for use in license application design and to provide guidance for site data 
gathering.
Changes and Status.  The information obtained for Information Needs 4.4.2 through 4.4.10 is 
being used as described, except that very little, if any, of the information obtained will be placed 
in the Reference Information Base.  Instead, the information will be presented in design analyses 
and system design description documents.
2.3.14	Information Need 4.4.2:  Characteristics and Quantities of Waste and Waste 
Packages Needed for Design (SCP Section 8.3.2.5.2)
Background and SCP Plans.  This information need was to serve as interface between waste 
package design and repository design.  It would be considered satisfied when waste package-
repository interface requirements were finalized and passed on to design requirements 
documents.  The section provided four waste-related parameters needed to support the 
information need and a nine-point logic process to support the selection of the parameters.
Changes and Status.  The current approach is generally consistent with the parameters and logic 
process described in the information need.  The exceptions are those items specifically related to 
borehole emplacement (a design concept not currently under consideration); the period of 
retrievability (increased from 50 to 300 years); and the waste quantities (will not appear in the 
generic requirements document).  The generic requirements document has been deleted from the 
document hierarchy.  (See the following discussion on Information Need 4.4.4 in 
Section 2.3.16.)  The waste quantities are stated in the Civilian Radioactive Waste Management 
System Requirements Document (DOE 1998c), Yucca Mountain Site Characterization Project 
Requirements Document (YMP 2001a), and Monitored Geologic Repository Project Description 
Document (Curry 2001), and in individual system description documents.  For example, 
commercial waste quantities and parameters can be found in the Uncanistered Spent Nuclear 
Fuel Disposal Container System Description Document (CRWMS M&O 2000i, p. 10).
2.3.14.1	Application of Results (SCP Section 8.3.2.5.2.1)
Background and SCP Plans.  This section provided a cross reference for how information from 
the associated information need would be used in other issues and information needs.
Changes and Status.  The current program approach uses the information obtained in this 
information need as specified in the SCP section.
2.3.15	Information Need 4.4.3:  Plan for Repository Operations During Construction, 
Operation, Closure, and Decommissioning (SCP Section 8.3.2.5.3)
Background and SCP Plans.  This information need was to produce a plan for repository 
operations.  The section described how design information was to be used to develop the 
operations plan and listed parameters planned as input to the plan.  Finally, the section provided 
a logic process for developing the plan.
Changes and Status.  The approach to developing the operations plan currently being pursued is 
consistent with that described, including use of the specified parameters and logic process.  The 
repository operations plan will not be further described in a repository design plan because there 
is no such plan; instead, the operations plan will be described in the Monitored Geologic 
Repository Project Description Document (Curry 2001).
2.3.15.1	Design Activity 4.4.3.1:  Operations Plan to Accompany the Advanced 
Conceptual Design (SCP Section 8.3.2.5.3.1)
Background and SCP Plans.  This design activity was to produce an operations plan to 
accompany advanced conceptual design that focused mainly on waste handling operations, 
including retrieval.
Changes and Status.  A concept of operations (operations plan) was included in the Mined 
Geologic Disposal System Advanced Conceptual Design Report (CRWMS M&O 1996g, 
Volume II, Section 5).  As planned in the SCP, this plan focused on waste handling operations, 
including retrieval.
2.3.15.2	Design Activity 4.4.3.2:  Operations Plan to Accompany the License Application 
Design (SCP Section 8.3.2.5.3.2)
Background and SCP Plans.  This design activity was to produce an operations plan to 
accompany the license application design.  The plan would contain the results of design 
decisions made during advanced conceptual design and would contain operations only for the 
selected emplacement option.  Sufficient detail would be included to support radiological and 
nonradiological safety analyses.
Changes and Status.  The concept of operations for Viability Assessment was developed in the 
Monitored Geologic Repository Concept of Operations (CRWMS M&O 1998e).  This was 
updated (CRWMS M&O 1999b) to reflect the concept that was to be presented in the site 
recommendation documentation and is now captured in the Monitored Geologic Repository 
Project Description Document (Curry 2001).  This work will lead to a concept of operations for 
license application.  The Project currently plans to develop the concept of operations in a manner 
consistent with that described in the information need.
2.3.15.3	Application of Results (SCP Section 8.3.2.5.3.3)
Background and SCP Plans.  This section described how the operations plan would be used.
Changes and Status.  The Project plans to use the operations plan in a manner consistent with 
that described.
2.3.16	Information Need 4.4.4:  Repository Design Requirements for Construction, 
Operation, Closure, and Decommissioning (SCP Section 8.3.2.5.4)
Background and SCP Plans.  This information need would be satisfied by the publication and 
control of the repository design requirements for each phase of repository design.  The 
information need called for clearly documenting and maintaining in the repository design 
requirements, the controlled assumptions and baseline design configuration.  Requirements 
planned to be considered in generation of the repository design requirements were listed and a 
graphic requirements document hierarchy was given in Figure 8.3.2.5-2 (DOE 1988).  A logic 
process was described for meeting the information need, including a description of how changes 
to the repository design requirements would be made.  Table 8.3.2.5 14 (DOE 1988) provided an 
organization of repository design requirements.
Changes and Status.  The approach during the Viability Assessment for documenting design 
requirements, organizing the design requirements documents, and controlling changes to the 
documents has changed from the approach provided in the information need.  This change is 
because the NRC commented that the flow-down and traceability of requirements were 
cumbersome and the DOE determined that requirements were written at too low a level of detail.  
The revised approach addresses these concerns.  The work required by this information need will 
be accomplished, but the requirements will not appear in the documents envisioned in the SCP 
(DOE 1988).  The generic requirements document discussed in the SCP has been superseded.  
The requirements document hierarchy for Viability Assessment consisted of Revision 03 of the 
Civilian Radioactive Waste Management System Requirements Document (DOE 1996d) (highest 
level), followed by Revision 2, DCN 2 of the Mined Geologic Disposal System Requirements 
Document (DOE 1996e) (next highest level), followed by two equal level documents, the 
Repository Design Requirements Document (YMP 1994d) and the Engineered Barrier Design 
Requirements Document (YMP 1994c).
The requirements document hierarchy has also been revised.  It is reflected in the Yucca 
Mountain Science and Engineering Report (DOE 2001a, 2.1.1.1 and Figure 2-2) and also will be 
reflected in the license application design.  The revisions to support design beyond the Viability 
Assessment (DOE 1998a) first involved developing Revision 04 of the Civilian Radioactive 
Waste Management System Requirements Document (DOE 1998c) and Revision 3 of the Mined 
Geologic Disposal System Requirements Document (YMP 1998b) to provide requirements 
generally written at a higher level than for the Viability Assessment.  A crosswalk was developed 
to provide traceability between these top-level requirements documents.  Requirements from the 
Repository Design Requirements Document (YMP 1994d) and the Engineered Barrier Design 
Requirements Document (YMP 1994c) were incorporated at a higher level in Revision 3 of the 
Mined Geologic Disposal System Requirements Document (YMP 1998b), which was approved in 
February 1998.  Along with some technical changes, the name of this last document was changed 
to the Monitored Geologic Repository Requirements Document by Revision 3, DCN 1 in 
April 1999 (YMP 1999).  The two lower-level documents have been removed from Level 2 
Change Control Board control (i.e., canceled) and archived to preserve their Viability 
Assessment status.  The Monitored Geologic Repository Requirements Document Revision 3, 
DCN 2, was approved in May 2000 (YMP 2000a).  It has since been superseded by the Yucca 
Mountain Site Characterization Project Requirements Document (YMP 2001a).  The Monitored 
Geologic Repository Project Description Document (Curry 2001) provides the flowdown and 
traceability of requirements to a number of system description documents used to implement 
applicable requirements and criteria.
2.3.16.1	Design Activity 4.4.4.1:  Repository Design Requirements for License 
Application Design (SCP Section 8.3.2.5.4.1)
Background and SCP Plans.  This design activity developed the repository design requirements 
for use in license application design.  The section described plans for updating the Repository 
Design Requirements Document (YMP 1994d) before the initiation of license application design; 
the update would contain substantially more detail on waste handling operations, a single 
emplacement orientation, and the results of numerous design decisions made during advanced 
conceptual design.
Changes and Status.  The update to the repository design requirements described in the design 
activity was made in a manner generally consistent with that described.  However, this update 
will occur in the project description and system description documents because there is no longer 
a separate repository design requirements document (see Section 2.3.16.1).
2.3.16.2	Application of Results (SCP Section 8.3.2.5.4.2)
Background and SCP Plans.  The section stated that the principal users of information obtained 
for the associated information need would be designers responsible for developing reference 
designs for the repository and its seals.  The section also provided a list of other issues and 
information needs that relate to this SLP section.
Changes and Status.  The Repository Design Requirements Document (YMP 1994d) was 
originally planned to answer the issues and information needs identified when the SCP 
(DOE 1988) was written.  However, these issues and information needs will now be addressed 
by the system description documents mentioned in the discussion of Information Need 4.4.4.
2.3.17	Information Need 4.4.5:  Reference Preclosure Repository Design (SCP 
Section 8.3.2.5.5)
Background and SCP Plans.  This information need was intended to result in development of a 
reference postclosure design.  The section stated that the Site Characterization Plan Conceptual 
Design Report (SNL 1987) was the reference design when the SCP (DOE 1988) was written and 
described how the advanced conceptual design and license application design would build on 
this design.  The section also discussed planned development of design reports, topical reports, 
tradeoff studies, etc.  In the logic section, the information need listed 10 supporting activities 
requiring site data and 7 that do not require site data.
Changes and Status.  The current approach to developing and documenting the reference 
postclosure design is consistent with that described in the information need, except that the 
design is not being documented in the Reference Information Base (YMP 1996b).  Instead, the 
design is being documented in various documents in the project baseline.  The list of supporting 
activities mentioned in the SCP (DOE 1988) is being accomplished.
2.3.17.1	Application of Results (SCP Section 8.3.2.5.5.1)
Background and SCP Plans.  This section stated how the reference designs will be used and 
provided a cross reference to other information needs that would use the information.
Changes and Status.  The current approach to developing and using the reference design is 
consistent with that provided in the SCP section.
2.3.18	Information Need 4.4.6:  Development and Demonstration of Required Equipment 
(SCP Section 8.3.2.5.6)
Background and SCP Plans.  This information need was the focal point for the equipment 
development program.  Four principal products were planned:  a list of equipment, designs for 
unique equipment, the equipment itself, and demonstrations to establish capabilities of the 
equipment.  The section described briefly how these products would be used.  Specific site 
parameters needed were listed.  The logic process listed a six-step approach to the development 
and demonstration of equipment.  Six system-elements considered potential candidates for 
equipment demonstration were listed.  Described were the development and demonstration of a 
prototype emplacement borehole boring machine and site data to support that demonstration.
Changes and Status.  The four products in this information need are being developed, and they 
are being used as described in the information need.  The site parameters listed are being 
addressed.  The logic process provided in the information need is consistent with the current 
approach, with two exceptions.  First, proof-of-principle tests for some potential types of 
emplacement equipment will be performed if determined necessary after the license application 
instead of before it.  This change is not considered a problem because, with the change in 
emplacement concept, potential repository emplacement equipment is much simpler than 
equipment that would have been needed to support borehole emplacement.  Proof-of-principle 
tests for some other equipment types and operations (e.g., bridge cranes and welding of waste 
packages) may occur before license application submittal.  The second exception is that the 
development process and proof-of-principle tests will be documented in design analyses and the 
system description documents mentioned in the discussion of Information Need 4.4.4, instead of 
in a repository design plan and topical reports.  The boring machine discussion no longer applies 
because the machine described is for excavating emplacement boreholes, which are not needed 
for horizontal-in-drift waste package emplacement.  Accordingly, the tests planned to be 
conducted in the ESF for this equipment were not performed.  Similarly, different emplacement 
and retrieval equipment is now being considered to support in-drift emplacement.  For normal 
conditions, retrieval equipment is assumed to be the same as emplacement equipment.  The 
Project has successfully demonstrated use of a tunnel boring machine in the ESF and in the 
ECRB Cross Drift at Yucca Mountain.  Use of a roadheader in the ESF has met with limited 
success in the welded tuff at the repository level.  The Project intends to let potential commercial 
manufacturers demonstrate the probable success of larger, more powerful roadheaders.
2.3.18.1	Application of Results (SCP Section 8.3.2.5.6.1)
Background and SCP Plans.  This section described how the equipment designs and 
performance would be used, including a cross reference to other information needs and issues.
Changes and Status.  The Project plans to use equipment design and performance information 
in a manner consistent with that provided in the SCP (DOE 1988) section but modified by the 
equipment changes mentioned in the discussion of Information Need 4.4.6.
2.3.19	Information Need 4.4.7:  Design Analyses, Including Those Addressing Impacts of 
Surface Conditions, Rock Characteristics, Hydrology, and Tectonic Activity 
(SCP Section 8.3.2.5.7)
Background and SCP Plans.  This information need was the principal place where rock 
mechanics analyses, hydrologic analyses, and ventilation calculations were discussed.  
Table 8.3.2.5-15 (DOE 1988) listed products and studies to support this information need.  Also 
listed were site parameters needed to perform the required analyses.  Underground system 
elements that require structural analyses were discussed in detail, including discussions of 
understandings of the phenomena.  Table 8.3.2.5-16 (DOE 1988) listed planned analyses.  The 
information need stated that sensitivity analyses would be performed and discussed codes 
planned for use in analyses.
Changes and Status.  The products, studies, and analyses planned in the SCP (DOE 1988) to 
address this information need are generally being developed.  There have been, however, some 
significant changes resulting from changing from borehole emplacement to in-drift 
emplacement, which means in-drift emplacement equipment will be developed instead of 
borehole emplacement equipment.  For the same reason, there will be no studies of emplacement 
borehole stability, borehole hydrology, and borehole liner compatibility, but similar studies will 
be conducted for in-drift emplacement.  Other changes include a Project policy establishing a 
longer period of retrievability.  This change was made because the Project has pursued a more 
focused approach that will include fewer studies than previously planned.  A longer retrievability 
period will allow a longer period of performance confirmation and therefore increased 
confidence that the more limited scope of site characterization has provided adequate 
understanding of predicted site and repository performance.  There has also been a change in 
ground support and lining strategy.  For the Viability Assessment (DOE 1998a), the concept in 
emplacement drifts was to install one robust ground support/lining system that was suitable for 
all ground classifications.  This approach was chosen to simplify ground support design and 
reduce costs.  This system would be installed immediately behind the tunnel boring machine.  
However, because this system did not allow geologic mapping within the emplacement drifts, a 
different ground support system would be used in every 10th emplacement drift (CRWMS 
M&O 1998f, p. 48).  In every 10th emplacement drift, and in all other excavations, temporary 
ground support compatible with the ground classification would be installed immediately behind 
the tunnel boring machine and a permanent lining would be installed later.  The present concept 
in emplacement drifts, as reflected in the Yucca Mountain Science and Engineering Report (DOE 
2001a, 2.3.4.1.2, 2.4.2), is to install a ground support system consisting of full-circle steel sets 
and wire mesh and rockbolts as appropriate in all emplacement drifts.  The ground support/lining 
system in all other excavations will be the same as for the Viability Assessment.  Also, results of 
reference calculations will not be placed in the Reference Information Base (YMP 1996b) for 
reasons mentioned in the discussion for Information Need 4.4.5.  Sensitivity analyses are being 
used in a manner consistent with the discussion in the information need; however, they are being 
performed for in-drift emplacement rather than for borehole emplacement.  The codes currently 
being used or planned for use are consistent with the discussion of codes in the information need.
2.3.19.1	Application of Results (SCP Section 8.3.2.5.7.1)
Background and SCP Plans.  This section described how the information obtained for the 
associated information need would be used, including a cross-reference to other analysis areas.
Changes and Status.  The Project plans to use information and analyses described in the 
associated information need in a manner consistent with that provided in the SCP (DOE 1988) 
section, with the exception of changes described in the preceding discussion for Information 
Need 4.4.7.
2.3.20	Information Need 4.4.8:  Identification of Technologies for Surface Facility 
Construction, Operation, Closure, and Decommissioning (SCP Section 8.3.2.5.8)
Background and SCP Plans.  This information need evaluated the effectiveness of site 
elements that affect design, construction, and operations of the repository facilities during the 
preclosure period.  Four criteria would be used for this purpose.  The section described the 
product of the information need and listed site parameters required to be addressed to support the 
information need.  Finally, the logic process intended to be used was described; the discussion 
included then-current understandings of the important processes and phenomena affecting the 
information need.
Changes and Status.  The Project is using the four evaluation criteria provided in the 
information need to address the information need.  The identified site parameters are being 
addressed.  The logic process described in the information need and the understandings 
contained in the discussion are current.  However, results will be documented in design analyses 
and system description documents instead of in the repository design plan and in topical reports.  
Also, there will not be a separate license application design report because the information that it 
would contain will be an integral part of the license application documentation.
2.3.20.1	Application of Results (SCP Section 8.3.2.5.8.1)
Background and SCP Plans.  This section described how the information obtained for the 
associated information need would be used, including a cross reference to other analysis areas.
Changes and Status.  The Project plans to use information and analyses described in the 
associated information need in a manner consistent with that provided in the SCP section.
2.3.21	Information Need 4.4.9:  Identification of Technologies for Underground Facility 
Construction, Operation, Closure, and Decommissioning (SCP Section 8.3.2.5.9)
Background and SCP Plans.  This information need constituted the assessment that all aspects 
of the underground facility could be constructed, operated, closed, and decommissioned using 
reasonably available technology.  The assessment was to be included in a summary chapter of 
the documents that define the reference postclosure repository designs.  A list of parameters 
needed, organized by system elements, was provided.  The information need also described the 
logic process for addressing the information need, organized by system element.
Changes and Status.  The approach to addressing the information need is generally consistent 
with that described.  The list of parameters and the understandings and plans in the logic process 
are also generally valid.  As stated in the previous discussion on Information Need 4.4.6, 
equipment demonstrations will occur after the license application is developed, not before as 
planned in the SCP (DOE 1988).  There will be no equipment development for borehole 
emplacement, but there will be comparable work for in-drift emplacement.  The SCP conclusion 
that no additional work is needed to develop a rock handling system is still valid, even though 
the excavation will no longer be predominantly by blasting.  Rock handling methods for 
excavation by tunnel boring machine were adequately demonstrated in the ESF and in the ECRB 
Cross Drift.  Documentation of the results will be in design analyses and the system description 
documents mentioned in the discussion for Information Need 4.4.4 instead of in topical reports 
as planned in the SCP.  Also, there will not be a separate license application design report 
because the information that it would contain will be an integral part of the license application 
documentation.
2.3.21.1	Application of Results (SCP Section 8.3.2.5.9.1)
Background and SCP Plans.  This section described how the information obtained for the 
associated information need would be used, including a cross reference to other analysis areas.
Changes and Status.  The Project plans to use information and analyses described in the 
associated information need in a manner consistent with that provided in the SCP section.
2.3.22	Information Need 4.4.10:  Determination that the Seals for Shafts, Drifts, and 
Boreholes Can be Placed with Reasonably Available Technology (SCP 
Section 8.3.2.5.10)
Background and SCP Plans.  This information need would determine if reasonably available 
technology was available for emplacing shaft, drift, and borehole seals.  A series of evaluations 
was planned.  Summaries of the results would be provided in major design reports, and topical 
reports would be developed.  Parameters needed to satisfy the information need were listed, and 
the logic process for obtaining the information discussed.
Changes and Status.  The planned approach to addressing this information need is consistent 
with that described in the information need, including the parameters and the logic process 
described.  The only difference is the results will be documented in design analyses and the 
system description documents mentioned in the previous discussion for Information Need 4.4.4 
instead of in topical reports as planned in the SCP (DOE 1988).  Also, there will not be a 

separate license application design report because the information that it would contain will be 
an integral part of the license application documentation.
2.3.22.1	Application of Results (SCP Section 8.3.2.5.10.1)
Background and SCP Plans.  This section described how the information obtained for the 
associated information need would be used.
Changes and Status.  The Project plans to use information and analyses described in the 
associated information need in a manner consistent with that provided in the SCP section.
2.3.23	Schedule for Preclosure Design and Technical Feasibility (SCP Section 8.3.2.5.11)
Background and SCP Plans.  This section of the SCP (DOE 1988) provided a schedule for 
addressing Information Needs 4.4.1 through 4.4.10.  Table 8.3.2.5-18 (DOE 1988) described 
major events and provided planned completion dates.
Changes and Status.  The schedule for obtaining information for key activities has been revised 
as described in the semiannual progress reports and this document.  This method of documenting 
changes is consistent with the text in the SCP (DOE 1988) section.  The schedules presented in 
the 1988 SCP were based on the DOEs June 1987 Mission Plan Amendment (DOE 1987a, 
Appendix B; 1987b, Appendix B), which assumed the license application for the repository 
would be submitted to the NRC in 1995.  In 1989, the Secretary of Energy assessed the progress 
and needs of the site characterization project, and a new schedule was adopted that planned for 
the submittal of the license application in FY 2002.  However, recent modification of the 
Programs schedule during this reporting period, deferred the site recommendation to the 
President until early 2002, and, consequently, deferred the submittal of the license application.  
The DOE is currently evaluating the schedule for the submittal of the license application to the 
NRC, if the site is recommended and approved.  The evaluation is considering the latest 
requirements of NRCs proposed 10 CFR Part 63 (64 FR 8640), recent interactions with the 
NRC, and the budgetary constraints from Congressional appropriations.

3.	SEAL PROGRAM (SCP SECTION 8.3.3)
3.1	INTRODUCTION
When the SCP (DOE 1988) was written, seals for boreholes, shafts, ramps, and emplacement 
drifts were considered to be of potentially great importance to repository performance.  
Accordingly, an entire SCP Section (8.3.3) was devoted to seals.
The Projects planned approach to investigating seal issues is generally consistent with the 
approach presented in the SCP.  However, work done in the late 1980s and early 1990s showed 
that adequate sealing could be achieved.  Therefore, seal design and issue investigation have 
received a relatively low priority in recent years.
For the advanced conceptual design, the Project summarized previous seal work and established 
a seal design for shafts, ramps, and boreholes, as well as a design for backfill of all underground 
openings except emplacement drifts.
Systems analysis work done in 1997 showed that sealing of shafts, ramps, and boreholes would 
still be needed.  The work developed recommendations for requirements for those seals.  The 
next step needed is the design for those seals.  Plans for specific investigations are described in 
the material that follows.
3.2	SUMMARY OF CHANGES IN SEAL PROGRAM
This section discusses, in order, each section contained in Section 8.3.3 of the SCP (DOE 1988), 
which outlined the seal program.  First, appropriate background is provided, and SCP plans are 
given.  Then the changes that have occurred since the SCP was written are discussed and the 
current Project status outlined.  In this discussion, references to sections, tables, and figures are 
to the SCP unless otherwise stated.
Seal Program (SCP Section 8.3.3)
Background and SCP Plans.  This section described the activities necessary to develop seal 
designs and demonstrate seal performance.  A one-page discussion described what was contained 
in following sections.
Changes and Status.  A separate status on this introductory section is not needed.
3.2.1	Overview of the Seal Program (SCP Section 8.3.3.1)
Background and SCP Plans.  This section provided a general discussion of the seal program 
planned, including the planned timing for seal testing, development, and installation.  The 
section described planned seal testing activities, and Figure 8.3.3.1-1 provided planned 
sequencing of seal activities (DOE 1988).
Changes and Status.  The presently planned approach to seal testing and installation is 
consistent with the approach described, including activity sequencing and planned testing.  
Testing during site characterization has been completed; testing during construction and 
emplacement will be needed.
3.2.1.1	Seal Environment (SCP Section 8.3.3.1.1)
Background and SCP Plans.  This section described the aspects of the site environment 
important to seal performance.  Listed was example information needed for design and 
evaluation of seals.
Changes and Status.  The current understanding of the site environment as applicable to seal 
performance is consistent with that presented in this section.  Plans to obtain the information 
shown in the section as being needed are listed.  As measurements become available, updates of 
the site environment are made.
3.2.1.2	Seal Components (SCP Section 8.3.3.1.2)
Background and SCP Plans.  This section contained a detailed discussion of seal components 
and described important properties for prospective seal materials.  The section stated that 
cementitious and clay materials have a high probability of creating acceptable seals and 
discussed supportive test results.
Changes and Status.  The current understanding of seal components is consistent with that 
described in the SCP section.  As the design work is completed, this information will be updated.
3.2.1.3	Seal Designs (SCP Section 8.3.3.1.3)
Background and SCP Plans.  This section cross-referenced other SCP Sections (6.2.8, 
8.3.3.2,4.2) and the Site Characterization Plan Conceptual Design Report (SNL 1987, 5.1.3, 5.2, 
5.3) for seal designs current when the SCP was written.  The section states that the advanced 
conceptual design and the license application design would be the next two phases in seal design.  
Planned studies and evaluations to support seal design are discussed.
Changes and Status.  For the advanced conceptual design, the Project summarized previous seal 
work and established a seal design for shafts, ramps, and boreholes, as well as a design for 
backfill of all underground openings except emplacement drifts.  The studies and analyses 
described in the SCP section will be performed in order to more definitively determine the need 
for and appropriateness of seals in various repository applications.
3.2.1.4	Seal Modeling (SCP Section 8.3.3.1.4)
Background and SCP Plans.  This section briefly described the planned use of models and 
codes to support performance evaluations of seals.
Changes and Status.  The planned approach to modeling seal performance is consistent with 
that provided in the SCP section.
3.2.2	Issue Resolution Strategy for Issue 1.12:  Have the Characteristics and 
Configurations of the Shaft and Borehole Seals Been Adequately Established to 
(a) Show Compliance with the Postclosure Design Criteria of 10 CFR 60.134 and 
(b) Provide Information for the Resolution of the Performance Issues? (SCP 
Section 8.3.3.2)
Background and SCP Plans.  This section of the SCP (DOE 1988) described how all seals for 
the repository would be addressed, provided the approach to resolving the issue, and 
demonstrated the approach graphically in Figure 8.3.3.2-1a (DOE 1988).  Figure 8.3.3.2-2 
showed the potential sealing subsystem, seal locations, and seal components.  Table 8.3.3.2-1a 
showed functions, processes, material properties, performance measures, tentative design goals, 
and needed confidence.  Table 8.3.3.2-2 described general design constraints to be passed to 
Issue 1.11.  Table 8.3.3.2-3 described hydrologic related site parameters, goals, confidence, etc., 
to support resolution of Issue 1.12.  Table 8.3.3.2-4 listed miscellaneous information needed to 
resolve Issue 1.12.  Table 8.3.3.2-5 showed design basis performance goals for the sealing 
subsystem (DOE 1988).
Changes and Status.  The planned approach to addressing the seal issue is consistent with that 
provided in this SCP section.  The parameters to be addressed in the tables will be addressed.  
The tentative design goals listed are being reevaluated for compatibility with the latest repository 
configuration and operations concepts.  The systems analysis work done in the Repository Seals 
Requirements Study (CRWMS M&O 1997k, Section 5.5) established recommendations for 
requirements for sealing shafts, ramps, and boreholes (see footnote 1, page I-1).
3.2.2.1	Information Need 1.12.1:  Site, Waste Package, and Underground Facility 
Information Needed for Design of Seals and Their Emplacement Methods 
(SCP Section 8.3.3.2.1)
Background and SCP Plans.  This information need was intended to obtain site, waste package, 
and underground facility data needed for seal design.  The section discussed the parameters listed 
in this discussion of Issue 1.1.2 (SCP Section 8.3.3.2) in some detail, including understandings 
current at the time the SCP (DOE 1988) was written.  Finally, the logic process applicable to 
addressing the information need was described.
Changes and Status.  The planned approach to obtaining information to support seal design is 
consistent with that described, including parameters to be addressed and the logic process 
planned for use.
3.2.2.1.1	Application of Results (SCP Section 8.3.3.2.1.1)
Background and SCP Plans.  This section stated how the data obtained for the associated 
information need would be used.
Changes and Status.  The Project plans to use the information obtained for this information 
need as described in the SCP section.
3.2.2.2	Information Need 1.12.2:  Materials and Characteristics of Seals for Shafts, 
Drifts, and Boreholes (SCP Section 8.3.3.2.2)
Background and SCP Plans.  This information need described how seal materials would be 
developed, described general types of information that would be needed, and stated that 
parameters needed were covered in the discussion of Issue 1.12 (DOE 1988, Section 8.3.3.2).  
Testing plans were described in the information need.  Table 8.3.3.2-6 (DOE 1988) listed 
potentially important seal component properties and why information on them was needed.  This 
investigation was intended to collect information to confirm the geochemistry of the 
groundwaters and rock units at the repository horizon.  This information would be used to 
confirm the predicted effects on seal materials, especially those associated with elevated 
temperatures, caused by the emplacement of waste in the repository.  This information was 
needed to ensure that the design for seals was compatible with the geochemical conditions under 
ambient and elevated temperature conditions.  Laboratory testing to determine material 
properties, establishing of hydraulic conductivity of various seals materials and consolidation 
testing of crushed tuff, and in situ testing to evaluate seals under realistic conditions would be 
conducted to address Information Need 1.12.2.
Changes and Status.  The approach to determining seal materials characteristics is consistent 
with that provided in the information need, including information needed and plans for testing.  
The objective has not changed since the SCP (DOE 1988) was issued, but the data needed to 
resolve this information need have not yet been obtained.  The initial effort to establish the 
technical basis for developing seal designs for the sealing program, using preliminary site 
geohydrologic data, has been documented (Fernandez, Kelsall et al. 1987) and actual 
recommendations for requirements for design were developed in 1997 (CRWMS M&O 1997k, 
Section 5.5).  Another report (Fernandez, Case et al. 1993) discussed the field testing program 
and technical rationale for consideration in adopting a sealing strategy for site characterization 
boreholes and underground access ways.  The report also discussed objectives and plans for a 
seal testing program consistent with the results of the evaluation of design, performance 
assessment, and regulatory requirements.  From upcoming design work, any additional tests 
necessary to meet performance objectives will be determined.  Numerous tests have been 
conducted to derive a degradation model for cementitious materials emplaced in a tuffaceous 
environment.  Some of these tests included hydrothermal experiments on samples of high-silica 
concrete and grout, numerical analysis to simulate the products of the laboratory experiments, 
and analysis to determine volumetric changes accompanying the reaction of cements and UE-25 
J#13 water.  Closure Seal Materials and Configuration (CRWMS M&O 2000j) discusses the 
current candidate materials for seals.
3.2.2.2.1	Study 1.12.2.1:  Seal Material Properties Development (SCP 
Section 8.3.3.2.2.1)
3.2.2.2.1.1	Activity 1.12.2.1.1:  Detailed Property Determination of Cementitious-
Based and Earthen Materials (SCP Section 8.3.3.2.2.1.1)
Background and SCP Plans.  This activity was to initiate laboratory testing to determine 
material properties for seal components.  General testing plans were described.
Changes and Status.  This activity is contained in Study Plan 8.3.3.2.2.1, Study Plan for Seal 
Material Properties Development (SNL 1996c).  That document is in agreement with the work 
expected as described in the SCP (DOE 1988).
3.2.2.2.1.2	Activity 1.12.2.1.2:  Hydraulic Conductivity and Consolidation Testing of 
Crushed Tuff (SCP Section 8.3.3.2.2.1.2)
Background and SCP Plans.  This activity established the hydraulic conductivity and 
consolidation behavior of crushed tuff to support development of criteria for shaft and drift 
backfill.  General test plans were described.
Changes and Status.  This activity is contained in Study Plan 8.3.3.2.2.1, Study Plan for Seal 
Material Properties Development (SNL 1996c).  That document is in agreement with the work 
expected as described in the SCP (DOE 1988).
3.2.2.2.2	Design Activity 1.12.2.2:  A Degradation Model for Cementitious Materials 
Emplaced in a Tuffaceous Environment (SCP Section 8.3.3.2.2.2)
Background and SCP Plans.  This activity was to develop a degradation model to provide 
insight into how material properties of seal components, especially permeability and strength, 
could alter after being in contact with tuff.  General test plans were described.
Changes and Status.  Based on the recommendations for requirements from the system study, 
this effort is needed, but the specifics of what is needed will be established based on the design 
work for seals.
3.2.2.2.3	Study 1.12.2.3:  In Situ Testing of Seal Components (SCP Section 8.3.3.2.2.3)
Background and SCP Plans.  This study was to initiate in situ testing to evaluate seal 
component behavior.  The process was presented for determining the need for in situ testing (the 
last two steps of which were incomplete when the SCP (DOE 1988) was written).  The section 
referred to the discussion on Issue 1.12 (see Section 8.3.3.2) for properties needed and provided 
a discussion of site properties needed for addressing Issue 1.12.  Discussed were the adequacy of 
data needed, emplacement concerns, and details of possible tests and studies.
Changes and Status.  The contents of Study Plan 8.3.3.2.2.3, Study Plan for In Situ Testing of 
Seal Components (SNL 1996d), are generally in agreement with the work expected as described 
in the information need.  This work is currently unfunded, and future work scopes will depend 
upon future systems studies to determine the needs and functions of seals.
3.2.2.2.4	Application of Results (SCP Section 8.3.3.2.2.4)
Background and SCP Plans.  This section stated how information obtained for the associated 
information need would be used.
Changes and Status.  The planned approach is consistent with the SCP section.
3.2.2.3	Information Need 1.12.3:  Placement Method for Seals for Shafts, Drifts, and 
Boreholes (SCP Section 8.3.3.2.3)
Background and SCP Plans.  This information need would develop the placement method for 
seals for drifts, shafts, and boreholes.  Listed are specific parameters of interest and the logic 
process expected to be needed to address the information need.
Changes and Status.  The present approach is consistent with the approach presented in the 
information need, including parameters needed and the logic approach.  Repository Closure and 
Sealing Approach (CRWMS M&O 2000k) presents the most recent information on placement 
methods for seals.
3.2.2.3.1	Application of Results (SCP Section 8.3.3.2.3.1)
Background and SCP Plans.  This SCP section stated how information obtained for the 
associated information need would be used.
Changes and Status.  The planned approach is consistent with the SCP section.
3.2.2.4	Information Need 1.12.4:  Reference Design of Seals for Shafts, Drifts, and 
Boreholes (SCP Section 8.3.3.2.4)
Background and SCP Plans.  This information need would provide the reference design for 
seals.  Parameters needed are those described in Information Need 1.12.1.  The information need 
also provided the logic process planned for the seal design effort.
Changes and Status.  The current approach to seal design is consistent with the approach 
provided in the information need.  However, a substantial portion of the sealing design 
information will not be developed until after the start of waste emplacement.
3.2.2.4.1	Design Activity 1.12.4.1:  Development of the Advanced Conceptual Design 
for Sealing (SCP Section 8.3.3.2.4.1)
3.2.2.4.1.1	Design Subactivity 1.12.4.1.1:  Define Subsystem Design Requirements 
(SCP Section 8.3.3.2.4.1.1)
Background and SCP Plans.  The objective of this subactivity was to develop design 
requirements for seal components.  The activity included seven tasks planned to support this 
effort.
Changes and Status.  Recommendations for the design requirements have been established in 
the system studies (CRWMS M&O 1997k, Section 5.5).
3.2.2.4.1.2	Design Subactivity 1.12.4.1.2:  Perform Trade-Off Studies to Support 
Advanced Conceptual Design Development (SCP Section 8.3.3.2.4.1.2)
Background and SCP Plans.  The objective of this subactivity was to provide technical 
justification for selection of seal design options.  The section explained the intended focus of 
advanced conceptual design work in this area, including seven planned trade-off studies.
Changes and Status.  Seal trade-off studies were addressed in the 1997 systems study (CRWMS 
M&O 1997k, Sections 1.3 and 1.5) discussed above.  The work done in that study was sufficient 
to support Viability Assessment.  Additional trade-off studies will be performed as determined 
necessary to support license application design.
3.2.2.4.1.3	Design Subactivity 1.12.4.1.3:  Develop Advanced Conceptual Design for 
Seals (SCP Section 8.3.3.2.4.1.3)
Background and SCP Plans.  The objective of this subactivity was to provide design details 
that could be used to support license application design and performance assessment activities.  
The section stated that the advanced conceptual design would summarize the results of trade-off 
studies and described some specific information to be included.
Changes and Status.  The Mined Geologic Disposal System Advanced Conceptual Design 
Report (CRWMS M&O 1996g, Volume II, Sections 9.4.3 and 9.4.4) presented the seal design, 
but it did not summarize all the information described in the subactivity because little or no 
design work has been done on seals since the Site Characterization Plan Conceptual Design 
Report (SNL 1987, Sections 5.1.3, 5.2, and 5.3) was written.  The advanced conceptual design 
for seals was adapted from the design in the Site Characterization Plan Conceptual Design 
Report by considering changes made to the repository layout since then.  Because advanced 
conceptual design is complete, all work under this design activity is now closed.  No additional 
seal design was performed to support the Viability Assessment; additional design will be 
performed as part of license application design.
3.2.2.4.2	Design Activity 1.12.4.2:  Development of the License Application Design for 
Sealing (SCP Section 8.3.3.2.4.2)
3.2.2.4.2.1	Design Subactivity 1.12.4.2.1:  Define Subsystem Design Requirements 
(SCP Section 8.3.3.2.4.2.1)
Background and SCP Plans.  The objective of this subactivity was to refine design 
requirements for sealing components to support license application design.
Changes and Status.  Work not performed under seals advanced conceptual design will be 
performed as part of license application design.  The exact scope of future work will depend 
upon future systems studies to determine the needs and functions of seals.  The systems study 
encompassed the work scope described in the SCP (DOE 1988), and determined requirements.  
The Subsurface Closure and Seal System Description Document (CRWMS M&O 1999m) 
contains the most recent requirements for seals.  The system description document will be 
updated as the design progresses.

3.2.2.4.2.2	Design Subactivity 1.12.4.2.2:  Perform Trade-Off Studies to Support 
License Application Design Development (SCP Section 8.3.3.2.4.2.2)
Background and SCP Plans.  The objective of this subactivity is to provide technical 
justification for the selection of final seal designs.  Several planned trade-off studies were listed.
Changes and Status.  As expected in the SCP (DOE 1988, Section 4.3), alternative seal design 
concepts were studied (trade-off studies) for various flow rates as part of the Viability 
Assessment (DOE 1998a, Volume 2, Section 4.3).  Additional studies will be performed as part 
of license application design.  Closure Seal Locations and Geologic Environment Study 
(CRWMS M&O 2000l) discusses possible locations for seals in ramps and ventilation shafts.  A 
summary of the seals design for the site recommendation is in the Yucca Mountain Science and 
Engineering Report (DOE 2001a, 2.3.4.8.1).
3.2.2.4.2.3	Design Subactivity 1.12.4.2.3:  Develop License Application Design for 
Seals (SCP Section 8.3.3.2.4.2.3)
Background and SCP Plans.  The objective of this subactivity is to provide the license 
application design for seals.  The description identified four activities to support this task.
Changes and Status.  Seal design will be performed as part of license application design.  The 
approach to be taken is expected to be consistent with that described in the subactivity.
3.2.2.4.3	Application of Results (SCP Section 8.3.3.2.4.3)
Background and SCP Plans.  This section described how information obtained to address the 
associated information need will be used.
Changes and Status.  The Program plans to use seal information obtained to support this 
information need in a manner consistent with that provided in the SCP section.
3.2.2.5	Schedule for Seal Characteristics (Issue 1.12) (SCP Section 8.3.3.2.5)
Background and SCP Plans.  This section of the SCP provided a schedule for addressing 
studies and design activities related to sealing.  Table 8.3.3.2-10 (DOE 1988) described major 
events and provided planned completion dates.
Changes and Status.  The schedule for obtaining information for key activities has been revised 
as described in past semiannual progress reports.  This method of documenting changes is 
consistent with the text in the SCP (DOE 1988) section.  The schedules presented in the 
1988 SCP were based on the DOEs June 1987 Mission Plan Amendment (DOE 1987a, 
Appendix B; DOE 1987b, Appendix B), which assumed the license application for the repository 
would be submitted to the NRC in 1995.  In 1989, the Secretary of Energy assessed the progress 
and needs of the site characterization project, and a new schedule was adopted that planned for 
the submittal of the license application in FY 2002.  However, recent modification of the 
Programs schedule during this reporting period, deferred the site recommendation to the 
President until early 2002, and, consequently, deferred the submittal of the license application.  
The DOE is currently evaluating the schedule for the submittal of the license application to the 
NRC, if the site is recommended and approved.  The evaluation is considering the latest 
requirements of NRCs proposed 10 CFR Part 63 (64 FR 8640), recent interactions with the 
NRC, and the budgetary constraints from Congressional appropriations.



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4.	WASTE PACKAGE PROGRAM (SCP SECTION 8.3.4)
4.1	INTRODUCTION
The Projects waste package design has changed substantially from the design concepts 
described in the SCP (DOE 1988).  Most changes to the design that have occurred have been 
caused by the change from a thin-walled, borehole-emplaced waste package to a thick-walled, 
in-drift-emplaced waste package.  This change was motivated in part by DOE goals for earlier 
waste acceptance.  In addition, the robust waste packages currently planned are believed to have 
many performance and cost advantages over the packages envisioned in the SCP.  Large, robust 
waste packages would allow fewer waste packages to be built and emplaced, would require a 
smaller total number of welds, would have thicker walls to attenuate radiation, and would have 
greater mechanical strength than would the containers envisioned in the SCP.  The robust, multi-
barrier packages would provide significantly longer containment than would the original thin-
wall concept.
Emplacing waste packages in drifts is also expected to have significant performance and cost 
advantages over borehole emplacement.  Drift emplacement would allow the packages to radiate 
heat to a larger area and thus would help control maximum temperatures.  A severe seismic event 
with shear displacements in the repository horizon would be less likely to damage drift-emplaced 
waste containers.  Drift emplacement would simplify emplacement operations and would 
maintain flexibility of thermal loading because waste packages could be spaced as needed along 
the drift.  Boreholes appear to have a greater tendency to accumulate groundwater and to confine 
the products of degradation.
Although the waste package design concept has changed substantially, the approaches embodied 
in the issue resolution strategies described in the SCP (DOE 1988) have not changed 
significantly.  A more detailed discussion of how and why the waste package and emplacement 
concepts have changed can be found in the discussion of 8.3.4 that follows.
The Projects approach to investigating the near-field environment is also generally consistent 
with the approach described in the SCP (DOE 1988), but the studies and activities described in 
the SCP have been reorganized.  Although the currently planned work scope is similar to that 
planned in the SCP, one study was split into two studies, and numerous activities under the 
various studies have been canceled and superseded by new studies.  These changes were made 
during the progress of site characterization for several reasons.  In some instances, the changes 
reflected improved understanding of the information needed to support performance assessment.  
In other instances, changes were made for convenience in organizing the work.  The near-field 
discussions in this section provide a cross-reference between the SCP studies and activities and 
current studies and activities.
The following sections explain how the Project plans to implement the SCP (DOE 1988) with 
regard to designing the waste package and obtaining an understanding of the near-field 
environment to support performance assessment and ensure the environment does not 
compromise the ability of the waste package to perform its design functions.
4.2	SUMMARY OF CHANGES IN THE WASTE PACKAGE PROGRAM
This section discusses in order each section contained in Section 8.3.4 of the SCP (DOE 1988), 
which outlined the waste package program.  First, appropriate background is provided and SCP 
plans are given.  Then the changes that have occurred since the SCP was written are discussed 
and the current Project status outlined.  In this discussion, references to sections, tables, and 
figures are to the SCP unless otherwise stated.
Waste Package Program (SCP Section 8.3.4)
Background and SCP Plans.  This section described the general strategy for waste package 
development and demonstration of postclosure compliance.  The strategy was shown graphically 
in Figure 8.3.4-1.
Changes and Status.  The strategy remains largely intact, and performance is still allocated to 
the waste package and other components of the engineered barrier segment.  The following 
changes have occurred.  Assumptions about water quality made in the SCP have been modified 
because of advances in understanding of the environment; the current assumptions are that 
introduced materials and thermal effects can result in large changes in near-field water chemistry 
(Wilder 1996).  Container materials chosen for use in the Viability Assessment design (CRWMS 
M&O 1997l, pp. 124126) have been changed to support the license application Enhanced 
Design Alternative II (EDA II) (CRWMS M&O 1999d), and testing will continue on a variety of 
corrosion resistant and corrosion allowance metals, as well as alternative container materials.  
Performance is still allocated not only to the containment barriers but also to the waste form and 
engineered environment.  Engineered environment means the components of the engineered 
barrier segment other than the waste package.  Performance allocation to spent nuclear fuel 
cladding is being considered.
Throughout this section and its subsections, there are references to small, thin-walled, single-
barrier waste packages that will be emplaced in vertical boreholes.  The current approach is to 
use large, thick-walled, multi-barrier waste packages that will be emplaced in drifts (CRWMS 
M&O 1996g, Volume I, p. 7-1).  This change will not be repeated in the discussions of lower-
level SCP sections that follow unless there are ramifications for other aspects of the discussion.
Using large, thick-walled, multi-barrier waste packages emplaced in drifts has many advantages 
over the packages envisioned in the SCP (DOE 1988).  Large packages would have a smaller 
surface area to volume ratio, so more costly materials and/or thicker layers could be used in the 
containment barriers without as great an effect on overall repository cost.  With large waste 
package capacities, the number of packages would be reduced, so there would be fewer closure 
welds to be made and inspected.  Thick container walls would absorb radiation, making the 
packages easier to handle by reducing measures required for radiation protection and reducing 
the effects of radiolysis on the near-field environment.  Thick walls would also provide greater 
mechanical strength in the event of a handling accident.  Multiple barriers reflect the defense-in-
depth concept and allow the designer to choose different and complementary materials that 
provide longer containment over a wide range of conditions.
Emplacing waste packages in drifts is also expected to have significant advantages.  Overall 
repository excavation costs are expected to be lower because boreholes are unnecessary.  Drift 
emplacement would allow the packages to radiate heat to a larger area, and thus would help 
control maximum temperatures.  A severe seismic event with shear displacements in the 
repository horizon would be less likely to damage drift-emplaced waste containers than 
borehole-emplaced containers because drift emplacement provides extra clearance between the 
containers and the drift wall.  Drift emplacement would simplify emplacement operations and 
would maintain flexibility of thermal loading, because packages could be spaced as needed along 
the drift.  Finally, there would be fewer concerns about corrosion and criticality.  Compared with 
drifts, boreholes appear to have a greater tendency to accumulate groundwater and to confine the 
products of degradation.
4.2.1	Overview (SCP Section 8.3.4.1)
Background and SCP Plans.  This section described three issues related to waste package 
development.  Relationships between design- and performance-related issues used in 
performance allocation were discussed and presented graphically in Figure 8.3.4.1-1 
(DOE 1988).
Changes and Status.  The issues described in the SCP (DOE 1988) section remain central to 
current efforts.  In spite of design changes, plans for the VA had minimal ventilation under 
normal operating conditions so the waste package environment would not depend strongly on 
whether the repository is operational or closed.  This assumption is consistent with that presented 
in the SCP section.  However, substantial ventilation during the preclosure period is now part of 
the reference design.  Interaction of Issues 1.10, 2.6, and 4.3 with other issues is still as described 
in Figure 8.3.4.1-1 (DOE 1988).  Issue 1.10 is still the only waste package design issue that 
involves the acquisition of site characterization data.
4.2.1.1	Waste Package Environment (SCP Section 8.3.4.1.1)
Background and SCP Plans.  This section described in general terms the environment into 
which the waste package would be placed and the expected effect of the waste package on that 
environment.  The section summarized understandings of the environment current at the time the 
SCP was written.
Changes and Status.  When the SCP (DOE 1988) was written, limited collapse of boreholes 
around the waste packages was expected and thus limited stresses from rockfall, although an 
oxidizing environment was clearly expected.  Emplacement drifts are now expected to collapse 
eventually, and substantial loading by rock impact is possible after drip shield failure.  Samples 
of water from the repository horizon have been obtained and analyzed (Yang, Rattray et al. 1996; 
Yang, Yu et al. 1998).  Thermal goals are still in effect (CRWMS M&O 1998c, EBDRD 3.7.G.1 
through EBDRD 3.7.G.6, pp. 4-26 through 4-34), but the goals have been modified to reflect 
changed designs.  Attempts are being made to use heat to reduce the aggressiveness of the 
environment.  The Yucca Mountain Science and Engineering Report, Executive Summary (DOE 
2001b, p. 21), contains an evaluation of the thermal operating modes.  The report notes that 
temperature-sensitive parameters and coupled thermal-hydrological-mechanical-chemical 
processes are being considered in analyses of the effects of lower temperatures on the in-drift 
environment.  These analyses will support sensitivity studies (i.e., studies designed to determine 
which models and parameters most significantly effect over all performance) to determine if 
lower-temperature operating modes have the potential to improve repository performance or 
reduce uncertainties in long term performance.
4.2.1.2	Waste Package Components (SCP Section 8.3.4.1.2)
Background and SCP Plans.  This section described considerations of waste package designs 
and discussed in very general terms the waste expected to be emplaced.
Changes and Status.  The waste packages envisioned by the authors of the SCP (DOE 1988) 
were smaller and generally simpler than those of current designs.  The general thrust of waste 
package design has changed because of ongoing efforts to provide long containment at a 
reasonable cost.  Major changes as a result of these efforts were the planned use of a thick-
walled, more robust waste container, and larger waste packages that could accommodate more 
waste.  Current designs also add a basket and basket guides in disposal containers for spent 
nuclear fuel, a canister guide in disposal containers for waste glass, and, in some cases, thermal 
shunts.  DOE-owned spent fuel has been added to the Program baseline, and a waste package 
that would contain both waste glass and DOE-owned spent fuel is being designed.  Various 
additional components may be needed to accommodate DOE-owned spent fuel.  Rod 
consolidation at the repository is no longer in the baseline (CRWMS M&O 1998c, Key 008, 
pp. 3-21).  Aggressive conditions are now accommodated by using drip shields and containers 
that include a highly corrosion-resistant barrier.  Alternative materials are also still under 
consideration.  Also, see the previous discussion of the waste package program (SCP 
(DOE 1988) Section 8.3.4).
4.2.1.3	Waste Package Designs (SCP Section 8.3.4.1.3)
Background and SCP Plans.  This section briefly described the general approach planned to be 
taken in designing the waste package, including understandings current at the time that the SCP 
and the objectives for the design work were written.  The section emphasized efforts in designing 
for mechanical loads and containment.
Changes and Status.  Current work continues to address the concerns noted in the SCP 
(DOE 1988) section, but emphasis on thermal design, long-term criticality control, and shielding 
has been substantially increased.  In the current design approach, requirements have been placed 
on the handling loads that the waste packages must sustain (CRWMS M&O 1999a, pp. 819), 
but the packages are so strong that there is little effect on design.  Requirements for containment 
by the waste package under accident conditions have been quantified (CRWMS M&O 1999a, 
pp. 819).  Current goals for containment are (CRWMS M&O 1999a, pp. 819) that no more 
than 1 percent of all waste packages will breach during the first 1,000 years after emplacement.
4.2.1.4	Waste Package Modeling (SCP Section 8.3.4.1.4)
Background and SCP Plans.  This section briefly described the planned approach to waste 
package modeling in support of design and performance assessment.
Changes and Status.  Waste package modeling has changed to the extent required by changes in 
design; notably, analyses of borehole failure have been replaced by analyses of rockfall.  (See the 
previous discussion of the waste package program (SCP Section 8.3.4).)  Processes included in 
postclosure modeling are essentially unchanged from those described in the SCP (DOE 1988).  
Some processes, such as radionuclide transport within the waste package, will be modeled at a 
higher (bounding) level of abstraction than was planned in the SCP because of the complexity of 
flow in a flooded, partially degraded waste package.
4.2.2	Issue Resolution Strategy for Issue 1.10:  Have the Characteristics and 
Configurations of the Waste Packages Been Adequately Established to (a) Show 
Compliance with the Postclosure Design Criteria of 10 CFR 60.135 (see footnote 1, 
page I-1) and (b) Provide Information to Support Resolution of the Performance 
Issues? (SCP Section 8.3.4.2)
Background and SCP Plans.  This section provided the overall strategy for dealing with two 
aspects of waste package postclosure behavior.  The first is related to waste package properties 
and interactions with the environment; the second is testing and analysis to support performance 
assessment.  The section presented the proposed approach to addressing these issues 
(DOE 1988), both in text and graphically in Figure 8.3.4.2-1.  Figure 8.3.4.2-2 demonstrated the 
proposed approach to modeling.  Table 8.3.4.2-1 presented model hierarchy and model inputs for 
the issue, including needed confidence.  Table 8.3.4.2-2 presented performance measures, 
tentative goals, and needed confidence for addressing the issue.  Table 8.3.4.2-3 presented 
performance parameters and goals for the issue.  Table 8.3.4.2-4 provided a list of input 
parameters for characterization models for the issue (DOE 1988).  The section also discusses a 
design envelope for the waste package that included eight considerations.  Design goals were 
discussed for each consideration.  A list of limits to alteration of water chemistry was also 
provided.
Changes and Status.  Although the general approach described in this section is still applicable, 
numerous details of its application have changed.  The structure of the model hierarchy for 
Issue 1.10 is generally still valid, but Borehole Stability (DOE 1988, Figure 8.3.4.2-2) has 
been replaced by Drift Stability because of changes in design emplacement mode.  In addition, 
synergistic effects are now thought to have substantial effects on performance, but these effects 
were not evident from the model hierarchy.  Effects of waste package degradation on criticality 
control were also missing from the hierarchy.  Model inputs for Issue 1.10 in Table 8.3.4.2-2 
(DOE 1988) are largely unchanged.  Changes in design have required substantial changes in 
performance measures, parameters, and goals.  Design basis loads for rock fall in Table 8.3.4.2-2 
have not yet been determined.  Tectonic processes are considered to be substantially less 
important for drift emplacement than for borehole emplacement, eliminating the possibility of 
shearing the waste package if the standoff requirements are adhered to.  The separate goal in 
Table 8.3.4.2-2 for containers breached by tectonic processes is no longer in effect because shear 
loading of the waste package by fault displacement is not considered to be a credible event 
(CRWMS M&O 1997m, Section 7.1.4).  Waste package materials have been changed from those 
used in the Viability Assessment design (CRWMS M&O 1997l, pp. 124126) to those to be used 
for EDA II.  Requirements have been set for the mechanical strength of the waste package 
(CRWMS M&O 1999a, pp. 819).  Goals for loads on waste packages (DOE 1988, 
Table 8.3.4.2-3) are no longer in effect because drift emplacement provides little control over 
such loads.
No longer in effect is the goal that the vadose water should remain similar to that in the 
undisturbed environment because emplaced materials and thermal effects are thought to cause 
significant changes in water chemistry, regardless of the thermal load.  The quantity of water that 
contacts the waste packages may be large for a few packages, contrary to the SCP (DOE 1988) 
assumption.  The current list of input parameters for models of containment and release is still 
being developed based on testing data.  Constraints on drift stability are now driven mostly by 
retrievability considerations.  Current waste package design constraints are more closely related 
to providing long containment to control release of radionuclides than the SCP predicted.  This 
approach has been taken because, when waste forms are isolated from the atmospheric 
environment of an unsaturated repository for an extended period of time, fission product decay 
histories result in lower releases of radioactivity when the waste packages are eventually 
penetrated.  (See the previous discussion of waste package environment, SCP Section 8.3.4.1.1.) 
Lateral inhomogeneity may occur at such a fine scale that separation of the site into regions as 
suggested in the SCP section may be impractical.  For example, one waste package may have a 
large water flux while adjacent waste packages have small fluxes.  Percolation rate and flow 
paths are still thought to be vital to performance.  Recent investigators have given a variety of 
percolation rates.  Quantitative predictions in the SCP for water flux are for an obsolete design; 
groundwater focusing (rather than diversion, as discussed in the SCP) is postulated to occur 
because of the disturbance of the host rock during excavation.  Design goals in the SCP section 
for water flux control are no longer in effect because of the difficulty of predicting and 
controlling fluxes over long times, but fluxes are expected to be small.  SCP design goals for 
drainage of emplacement boreholes are no longer in effect because of changes in design 
emplacement mode.  SCP design goals for rock-induced load on the waste package are no longer 
in effect because the emplacement mode has changed, but efforts are ongoing to specify design 
basis rock falls applicable to the in-drift mode currently under consideration.  Design goals for 
thermal loading have been modified; emphasis is now on using decay heat to keep containers dry 
as long as possible rather than for an arbitrary period of 300 years as specified in the SCP 
because of Project emphasis on very long containment.  It is now expected that thermal operation 
of the repository may vary from hot to cold based on the performance of future sensitivity studies 
(DOE 2001b, p. 21).  The SCP goal of characterizing the inventory of primary radionuclides to 
within 20 percent is no longer in effect because the goal is considered inappropriately stringent.  
Related goals of using decay heat to provide a benign environment and of controlling criticality 
will have a similar effect.
Selection criteria are being used in place of SCP (DOE 1988) design goals for container 
materials (CRWMS M&O 1997l, pp. 124126).  Several candidate materials have been 
considered for each waste package component, and the performance of these materials has been 
compared.  Use of selection criteria is expected to provide an equivalent design benefit to that 
obtained through use of design goals.  The SCP design goal for fabrication is still in effect; 
corrosion tests will include welded samples.  SCP design goals for the borehole liner are no 
longer applicable because current designs do not include this component.  Limits to alteration of 
water chemistry are no longer in effect.  The VA design included a full concrete lining for 
emplacement drifts, which could easily produce changes in pH that exceed the prescribed limit.  
However, these changes were expected to promote long containment because high values of pH 
(to a point) tend to result in low corrosion rates for carbon steel.  In contrast, the current SR 
design does not create high pH conditions because it consists of full circle steel sets with wire 
mesh and rockbolts, as appropriate, and minimizes the use of concrete and grout (see footnote 1, 
page I-1).
4.2.2.1	Information Need 1.10.1:  Design Information Needed to Comply With 
Postclosure Criteria from 10 CFR 60.135 (a) for Consideration of the 
Interactions Between the Waste Package and Its Environment (SCP 
Section 8.3.4.2.1)
Background and SCP Plans.  This information need was intended to show that relevant 
environmental factors would be considered in waste package design.  The section provided a list 
of parameters to be addressed and briefly stated the logic planned to be used.
Changes and Status.  The current Program approach is consistent with that described in the 
information need, including the list of parameters and the logic.  The list of factors from 
10 CFR 60.135(a)(2) is incomplete, but the missing parameters may be addressed in the future 
(see footnote 1, page I-1).
4.2.2.1.1	Design Activity 1.10.1.1:  Consideration of 10 CFR 60.135(a) factors (SCP 
Section 8.3.4.2.1.1)
Background and SCP Plans.  This design activity was intended to explicitly show that the 
factors specified in 10 CFR 60.135(a) and listed as parameters in the associated information need 
would be considered in waste package design.
Changes and Status.  The current Program approach was consistent with that described in the 
design activity.
4.2.2.1.2	Application of Results (SCP Section 8.3.4.2.1.2)
Background and SCP Plans.  This section stated that analysis results under the associated 
information need would be used to show explicitly that the factors enumerated in 
10 CFR 60.135(a) were considered and that properties or interactions do not compromise 
repository performance, waste package functions, or the geologic setting.
Changes and Status.  Information obtained to address the associated information need is being 
used in a manner consistent with that described in the SCP section (see footnote 1, page I-1).
4.2.2.2	Information Need 1.10.2:  Reference Waste Package Designs (SCP 
Section 8.3.4.2.2)
Background and SCP Plans.  This information need provided an approach to developing 
reference waste package designs.  Parameters are listed and the planned logic process briefly 
described.
Changes and Status.  Because of changes in program direction and demands for higher 
performance, waste package designs have been modified from those referenced in this section of 
the SCP (DOE 1988).  All physical characteristics identified are still applicable.  The number of 
waste packages loaded at the MGR in a given year is presented in the Waste Quantity, Mix and 
Throughput Study Report (CRWMS M&O 1997n, Table 5-11).  Configurations of packages for 
the EDA II (CRWMS M&O 1999d) design are available, but only without tolerances.  Maximum 
waste package weights for the Viability Assessment designs (DOE 1998a) are available; weights 
for the SR design are available in the Yucca Mountain Science and Engineering Report (DOE 
2001a, p. 3-14).  Mechanical and thermal properties of component materials are available in the 
literature.  Both output characteristics identified in the SCP are still applicable.  Techniques are 
available to calculate both the heat generation rate and ionizing radiation flux.
4.2.2.2.1	Application of Results (SCP Section 8.3.4.2.2.1)
Background and SCP Plans.  This section stated how reference and alternative waste package 
design information would be used.
Changes and Status.  The strategy for application of waste package design results is basically 
unchanged.  However, alternative waste package designs are no longer being carried as planned 
in the SCP because of increased confidence in the adequacy of current designs.
4.2.2.3	Information Need 1.10.3:  Reference Waste Package Emplacement 
Configurations (SCP Section 8.3.4.2.3)
Background and SCP Plans.  This information need described the reference waste package 
conceptual design and information needed for further design development.  Specific parameters 
are listed and a general logic process is discussed.
Changes and Status.  The logic of the current program approach is consistent with the approach 
presented in the information need.  The emplacement configuration, however, has been changed 
to multi-barrier waste packages emplaced in drifts.  This change is discussed further in 
Section 4.1 of this document.  In addition, alternative designs are no longer being carried because 
of increased confidence in the adequacy of current designs.  Although the reference thermal 
loading has changed (CRWMS M&O 1999e), thermal loading is still an important consideration 
as predicted in the SCP (DOE 1988).  The changes in the emplacement configuration cause 
corresponding changes in the list of parameters.  The various borehole parameters listed in the 
SCP are irrelevant because there are no boreholes in current designs.  Significant parameters now 
include waste package spacing, emplacement drift layout and dimensions, and configuration of 
waste package support hardware, invert, and other components of the underground facilities.  
Because the project baseline has been extended to include waste forms other than commercial 
spent nuclear fuel and glass waste forms, information on emplacement configuration for waste 
package types must also be extended to include these waste forms.
4.2.2.3.1	Application of Results (SCP Section 8.3.4.2.3.1)
Background and SCP Plans.  This section stated how reference and alternative emplacement 
configuration design information would be used.
Changes and Status.  The current program approach uses information obtained for this 
information need in a manner consistent with that described in this SCP section.  However, 
alternative designs are no longer being carried as planned in the SCP because of increased 
confidence in the adequacy of current designs.
4.2.2.4	Information Need 1.10.4:  Postemplacement Near-Field Environment (SCP 
Section 8.3.4.2.4)
Background and SCP Plans.  This information need was intended to evaluate the attributes of 
the near-field environment and to establish the extent of physical and chemical interactions 
expected between the waste package materials and water present in or mobilized from the 
repository host rock.  Parameters to be addressed are listed.  The information need also provided 
a planned logic, which included a list of attributes that affect water chemistry.
Changes and Status.  This information need was intended to ensure that interactions with the 
emplacement environment do not compromise the function of the waste packages.  Compositions 
and amounts of water that may contact the waste package are of critical importance in 
evaluations of waste package performance.  During the investigation, data are collected and 
analyzed and models are developed and exercised to enhance the understanding of the coupled 
thermal-mechanical-hydrological-chemical (TMHC) processes expected to exist in the near-field 
of a potential repository.  The understanding of coupled TMHC processes will be used to predict 
the composition and amount of water that may contact the waste packages.  This information will 
be used to evaluate design configurations as well as containment and controlled release 
performance issues.
Significant advances in collecting the information required for this information need have been 
made.  The G-Tunnel test was completed at the Nevada Test Site to improve understanding of 
the thermal-hydrological process in an underground environment and to evaluate prototype 
instruments and test methodologies.  Three field tests are being conducted at Yucca Mountain to 
enhance understanding of the coupled TMHC processes:  the Large Block Test, the Single 
Heater Test, and the Drift Scale Test.  The Large Block Test is a controlled TMHC experiment 
conducted on a 3x3x4.5 m block of Topopah Spring Tuff at Fran Ridge, Nevada.  Heaters were 
placed in the block at about 2.75 m from its top.  The heaters were energized on 
February 28, 1997.  The temperature at the top was maintained at 60C, while the heater zone 
reached a temperature of about 135C.  These temperature conditions were maintained for about 
two months before the heaters were turned off to start a natural cool-down phase.  The test was 
terminated on September 30, 1998; the post-test sampling and testing were done in FY 1999; and 
a report, Electrical Imaging at the Large Block Test-Yucca Mountain, Nevada (Ramirez and 
Daily 2000), was prepared in FY 2000.  The 2000 report clearly delineates the drying and 
wetting of the rock mass during the 13 months of heating and subsequent six months of cool 
down.  The main feature is a prominent dry zone that forms around the heaters and gradually 
disappears as the rock cools.  Other features include linear anomalies of decreasing moisture 
content, which are fractures dehydrating as the block heats.  There are also examples of compact 
anomalies of wetting.  Some of these appear to be water accumulation in fractures that are 
draining condensate from the block, others may be rainwater entering a fracture at the top of the 
block.  During cool-down, a general rewetting is observed.  The Large Block Test provides tests 
of the drying, condensation, and condensate refluxing processes and allows observation of the 
mechanical behavior and the rock-water interaction during those processes.  The Large Block 
Test Status Report (Wilder et al. 1997) documents the status of and results obtained from the 
Large Block Test through FY 1997.
The Single Heater Test was conducted in Alcove 5 of the ESF at Yucca Mountain.  The primary 
objective of the Single Heater Test was to study the thermal-mechanical properties of the 
Topopah Spring Tuff rock mass.  The heating was started on August 23, 1996 and ended on 
May 28, 1997.  After the heating phase was completed, cool-down phases began, and the post-
test sampling and analyses were completed.  The test was terminated in January of 1998.  Further 
information on the Single Heater Test is contained in Section 1.12.1.  Partial results have been 
documented in a series of status and interim reports, including the Single Heater Test Final 
Report (CRWMS M&O 1999l).
The ongoing Drift Scale Test is also conducted in Alcove 5 of the ESF and will provide an in situ 
test of the coupled TMHC processes.  The rock mass is heated by both floor heaters and wing 
heaters along the heated drift.  The heaters cover an area of about 1500 m2 of the rock mass.  The 
heating phase of the Drift Scale Test was started on December 3, 1997, and will last for about 
4 years.  The spatial distribution and temporal variation of temperatures, moisture contents, 
mechanical deformations, and chemical properties are being monitored.
Laboratory experiments continue to be conducted using core and small block samples for the 
determination of thermal-hydrological-mechanical-chemical behavior including specific 
properties and coupled processes.  Numerical analyses of thermally-driven hydrological, 
mechanical, and chemical processes are ongoing.  AMRs Drift-Scale Coupled Processes (DSF 
and THC Seepage) Models (BSC 2001i), Coupled Thermal-Hydrologic-Mechanical Effects on 
Permeability Analysis and Models Report (BSC 2001l), and Thermal Tests Thermal-
Hydrological Analysis/Model Report (BSC 2001m) document the status and results obtained to 
date on this information need.
As the draft study plans pertaining to this information need were written and revised, the 
associated studies and activities were reorganized.  Study 1.10.4.1 (see Section 4.2.2.4.1 below) 
was split into two studies (itself, SCP 8.3.4.2.4.1, and SCP 8.3.4.2.4.6, Introduced Materials).  
During the study plan writing process, the work was redistributed among activities in the four 
original studies.  The cross linkage was originally described in several revisions of the Site 
Design and Test Requirements Document (YMP 1995b).  However, study plan objectives are not 
included in the current revision of the Site Design and Test Requirements Document 
(YMP 1995b).
4.2.2.4.1	Study 1.10.4.1:  Characterize Chemical and Mineralogical Changes in the 
Postemplacement Environment (SCP Section 8.3.4.2.4.1)
Background and SCP Plans.  This study established the compositional features of water that 
might contact the waste packages by determining the effects of chemical reactions on the rock-
water system.  The study had seven activities.
Changes and Status.  Before writing the study plan, the study was divided into two studies 
(near-field geochemistry and introduced materials).  The approach planned to be taken in the two 
studies developed from study 1.10.4.1 is consistent with the approach described in the 
Study 1.10.4.1 section of the SCP (DOE 1988).  When the near-field geochemistry study plan 
was drafted, the activities supporting the new Study 1.10.4.1 were organized differently than in 
the SCP.  To avoid confusion between similarly numbered old and new activities, the new 
activities were renumbered with higher numbers.  The cross linkage of the original activities to 
the current activities is described in the following sections.
4.2.2.4.1.1	Activity 1.10.4.1.1:  Rock-Water Interactions at Elevated Temperatures 
(SCP Section 8.3.4.2.4.1.1)
Background and SCP Plans.  This activity, which was intended to establish the identity and 
abundance of reaction products that form during hydrothermal interaction of tuff and reference 
groundwater at elevated temperatures, was deleted by a change to the Site Design and Test 
Requirements Document (YMP 1995b).  The objectives of the activity were moved to new 
Activities 1.10.4.1.8, 1.10.4.1.9, and 1.10.4.1.11.
Changes and Status.  The breadth of this activity, as captured in the current activities, has 
increased.  Some regions of the repository are expected to become saturated for various lengths 
of time; this activity will consider these situations.  Some experiments will be done at lower 
temperatures than the 90?C stated because of advances in experimental capabilities.  Water 
chemistries modified from the representative vadose water will be considered; these 
modifications are caused by heat and the mobilization of water.  Additional techniques, such as 
flow-through reactors, will be used, in addition to the Dickson-type rocking autoclave 
experiments.  Experiments will include crushed tuff as well as wafers, and solid reaction 
products will be considered in the experiments.
4.2.2.4.1.2	Activity 1.10.4.1.2:  Effect of Grout, Concrete, and Other Repository 
Materials on Water Composition (SCP Section 8.3.4.2.4.1.2)
Background and SCP Plans.  This activity was intended to test rock-water interaction in the 
presence of materials introduced into the natural environment.
Changes and Status.  This activity is now reported under Activity 1.10.4.5.1 because of changes 
to the site characterization program.  The change was made because, as alternatives to the SCP 
waste package design were proposed, numerous alternative materials for design elements have 
been considered.  Subsequent to this change, an additional study has been identified (1.10.4.5) to 
characterize the effects of introduced materials on chemical and mineralogical changes in the 
post-emplacement environment.  The approach planned to be taken in Activity 1.10.4.5.1 to 
address the objectives of Activity 1.10.4.1.2 is consistent with the approach described for 
Activity 1.10.4.1.2 in the SCP.  The SR drift design has been changed to rock bolts and full steel 
sets, thereby eliminating the use of most of the concrete and grout.  This change reduces the need 
for rock water interaction tests with concrete-type materials.
4.2.2.4.1.3	Activity 1.10.4.1.3:  Composition of Vadose Water From the Waste 
Package Environment (SCP Section 8.3.4.2.4.1.3)
Background and SCP Plans.  This activity was intended to characterize the composition of 
vadose water in the unsaturated, pre-emplacement waste package environment.
Changes and Status.  The objectives of this activity are met by Study 8.3.1.2.2.7.  (See 
Section 1.1.2 of this document.)  The approach planned to be taken in Study 8.3.1.2.2.7 to 
address the objectives of Activity 1.10.4.1.3 is consistent with the approach described for 
Activity 1.10.4.1.3 in the SCP.
4.2.2.4.1.4	Activity 1.10.4.1.4:  Dissolution of Phases in the Waste Package 
Environment (SCP Section 8.3.4.2.4.1.4)
Background and SCP Plans.  This activity was intended to determine the dissolution kinetics of 
the phases present in the waste package environment
Changes and Status.  The objectives of this activity were moved to new Activity 1.10.4.1.10.  
In addition to addressing all the work described in the original activity, using an approach 
consistent with the SCP text, the current activity will consider two additional parameters, surface 
area and solution composition.
4.2.2.4.1.5	Activity 1.10.4.1.5:  Effects of Radiation on Water Chemistry (SCP Section 
8.3.4.2.4.1.5)
Background and SCP Plans.  This activity was intended to determine the composition of water 
in the presence of a radiation field under postemplacement conditions.
Changes and Status.  The objectives of this activity were moved to new Activities 1.10.4.1.12 
and 1.10.4.5.7.  The approach planned to be taken in the current activities to address the 
objectives of Activity 1.10.4.1.5 is consistent with the approach described for Activity 1.10.4.1.5 
in the SCP.
4.2.2.4.1.6	Activity 1.10.4.1.6:  Effects of Container and Borehole Liner Corrosion 
Products on Water Chemistry (SCP Section 8.3.4.2.4.1.6)
Background and SCP Plans.  This activity was intended to determine the effect of corrosion 
products on the composition of water in the waste package environment.
Changes and Status.  The activity is reported under Activity 1.10.4.5.2 because of changes to 
the site characterization program.  This change was made because, as alternatives to the SCP 
waste package design have been proposed, numerous alternative materials for design elements 
have been considered.  Subsequent to this change, an additional study has been identified 
(1.10.4.5) to characterize the effects of corrosion products of introduced materials on chemical 
and mineralogical properties in the post-emplacement environment.  In addition to addressing all 
the work described in the original activity, using an approach consistent with the SCP text, the 
current activity will consider one additional parameter, initial water composition.
4.2.2.4.1.7	Activity 1.10.4.1.7:  Numerical Analysis and Modeling of Rock-Water 
Interaction (SCP Section 8.3.4.2.4.1.7)
Background and SCP Plans.  This activity was intended to examine effects and processes in 
natural systems for time periods and chemical conditions not duplicated by laboratory studies.
Changes and Status.  This activity is also reported under Activity 1.10.4.5.1 because the 
activity was divided between geochemistry and introduced material activities in the Site 
Characterization Program Baseline (YMP 1994a).  The geochemistry objectives were moved to 
new Activities 1.10.4.1.13, 1.10.4.1.14, and 1.10.4.1.15.  The Project plans to perform work 
described in the original activity in a manner consistent with the approach described in the SCP 
(DOE 1988).  In addition to EQ3/6, other codes have also been evaluated, and some are being 
used because of the advances in geochemical computation capabilities.  Reaction progress (in 
both the minerals and the fluid) along flow pathways is now being calculated in addition to 
reaction progress at a given location; this has also been made possible by advancements in the 
state of the art.
4.2.2.4.2	Study 1.10.4.2:  Hydrologic Properties of Waste Package Environment (SCP 
Section 8.3.4.2.4.2)
Background and SCP Plans.  This study was to establish the hydrologic properties of the near-
field repository rock and the effect of thermal perturbations on those properties.  Fracture versus 
matrix flow and gas-phase versus liquid-phase flow are addressed.  The section describes how 
flow and transport models will be used, as well as how boundary conditions for waste package 
performance assessment will be developed.
Changes and Status.  This study had three activities in the SCP (DOE 1988), 
Activities 1.10.4.2.1, 1.10.4.2.2 and 1.10.4.2.3.  When the study plan was written and 
subsequently revised, the material was organized differently than in the SCP.  To avoid 
confusion between similarly numbered old and new activities, the new activities were 
renumbered with higher numbers (1.10.4.2.4, 1.10.4.2.5 and 1.10.4.2.6).  The cross linkage of 
the original activities to the current activities follows.
4.2.2.4.2.1	Activity 1.10.4.2.1:  Single-phase fluid system properties (SCP 
Section 8.3.4.2.4.2.1)
Background and SCP Plans.  This activity was intended to establish the single-fluid-phase 
hydrologic properties of fractured and unfractured tuff under both isothermal conditions and a 
thermal gradient.
Changes and Status.  The objectives of this activity were moved to new Activities 1.10.4.2.4 
and 1.10.4.2.5.  The approach planned to be taken in the current activities to address the 
objectives of Activity 1.10.4.2.1 is consistent with the approach described for Activity 1.10.4.2.1 
in the SCP.
4.2.2.4.2.2	Activity 1.10.4.2.2:  Two-Phase Fluid System Properties (SCP 
Section 8.3.4.2.4.2.2)
Background and SCP Plans.  This activity was intended to establish the two-phase hydrologic 
properties of fractured and unfractured tuff under both isothermal conditions and a thermal 
gradient.
Changes and Status.  The objectives of this activity were moved to new Activities 1.10.4.2.4 
and 1.10.4.2.5.  The approach planned to be taken in the current activities to address the 
objectives of Activity 1.10.4.2.2 is consistent with the approach described for Activity 1.10.4.2.2 
in the SCP.
4.2.2.4.2.3	Activity 1.10.4.2.3:  Numerical Analysis of Flow and Transport in 
Laboratory Systems (SCP Section 8.3.4.2.4.2.3)
Background and SCP Plans.  This activity was intended to use laboratory-scale tests for initial 
development and validation of flow and transport in laboratory systems.
Changes and Status.  The objectives of this activity were moved to new Activities 1.10.4.2.5 
and 1.10.4.2.6.  The approach planned to be taken in the current activities to address the 
objectives of Activity 1.10.4.2.3 is consistent with the approach described for Activity 1.10.4.2.3 
in the SCP.
4.2.2.4.3	Study 1.10.4.3:  Characterization of the Geomechanical Attributes of the 
Waste Package Environment (SCP Section 8.3.4.2.4.3)
Background and SCP Plans.  This study establishes the mechanical attributes of the near-field 
host rock.
Changes and Status.  The original study from the SCP (DOE 1988) had one activity, 1.10.4.3.1 
Waste Package Environment Stress Field Analysis.  When the study plan was written, the 
material was organized differently than in the SCP.  The SCP activity was subdivided into three 
activities:  (1) Block Stability Analysis, (2) Borehole Damage Analysis, and (3) Geomechanical 
Properties Analysis (Activities 1.10.4.3.1, 1.10.4.3.2, and 1.10.4.3.3, respectively).  The cross 
reference between the original SCP activity and the current activities follows.
4.2.2.4.3.1	Activity 1.10.4.3.1:  Waste Package Environment Stress Field Analysis 
(SCP Section 8.3.4.2.4.3.1)
Background and SCP Plans.  This activity was intended to estimate the time-dependent stress 
field and displacements of the rock in the waste package environment.  This section listed five 
parameters to be addressed and described the evaluations to be performed.
Changes and Status.  The Project plans to use the three current activities created to reorganize 
this activity to address the information described in the original activity in a manner consistent 
with the SCP text.
4.2.2.4.4	Study 1.10.4.4:  Engineered Barrier System Field Tests (SCP 
Section 8.3.4.2.4.4)
Background and SCP Plans.  This study was to implement field tests needed to validate and 
establish the applicability of laboratory studies to the repository block.  The section discusses use 
of prototype tests to develop test procedures and protocols.
Changes and Status.  The original study from the SCP (DOE 1988) had three activities:  
1.10.4.4.1, Repository Horizon Near-Field Hydrologic Properties; 1.10.4.4.2, Repository 
Horizon Rock-Water Interaction; and 1.10.4.4.3, Numerical Analysis of Fluid Flow and 
Transport in the Repository Horizon Near-Field Environment.  When the study plan was written 
and subsequently revised, the material was organized differently than in the SCP.  The current 
activity organization is:  1.10.4.4.1, In Situ Testing; 1.10.4.4.2, Sampling and Sample Analyses; 
and 1.10.4.4.3, Pre- and Post-Test Calculations.  The cross linkage of the original activities to the 
current activities follows.
4.2.2.4.4.1	Activity 1.10.4.4.1:  Repository Horizon Near-Field Hydrologic Properties 
(Retitled In Situ Testing) (SCP Section 8.3.4.2.4.4.1)
Background and SCP Plans.  This activity was intended to determine the in situ hydrologic 
properties of rock in the repository horizon under thermally perturbed conditions.  This section 
listed eight parameters to be addressed and also discussed how instrumentation would be 
deployed and stated that laboratory-scale hydrologic studies would be performed.
Changes and Status.  The approach planned to be taken in the new activities to address the 
objectives of Activity 1.10.4.4.1 is consistent with the approach described for the activity in the 
SCP.
4.2.2.4.4.2	Activity 1.10.4.4.2:  Repository Horizon Rock-Water Interaction (Retitled 
Sampling and Sample Analysis) (SCP Section 8.3.4.2.4.4.2)
Background and SCP Plans.  This activity was intended to determine the effect on water 
chemistry of thermal perturbation of the near-field environment.  This section listed four 
parameters to be addressed and also described how instrumentation would be deployed and how 
tests would be performed.  Finally, the section provided a listing of models and technical 
procedures planned to support the activity.
Changes and Status.  The approach planned to be taken in the current activities to address the 
objectives of Activity 1.10.4.4.2 is consistent with the approach described for the activity in the 
SCP.
4.2.2.4.4.3	Activity 1.10.4.4.3:  Numerical Analysis of Fluid Flow and Transport in the 
Repository Horizon Near-Field Environment (Retitled Pre- and Post-Test 
Calculations) (SCP Section 8.3.4.2.4.4.3)
Background and SCP Plans.  This activity was intended to validate and calibrate fluid flow, 
temperature, and transport models using waste package-scale field studies.  This section listed 
ten parameters to be addressed and also described in general terms the approach to be taken to 
address the activity, including studies to be performed and models planned to be used.  The 
section also provided a list of technical procedures to be used to address the activity.
Changes and Status.  Some changes from the SCP (DOE 1988) description of this activity have 
occurred.  The last paragraph in the SCP description of this activity describes an in situ test to 
monitor the movement of sorbing and nonsorbing species; the activity includes numerical 
analysis of the test.  Current plans for in situ tests do not include such a test before License 
Application submittal.  The use of tracers is not feasible in the drift-scale (heater) test because 
test instruments are primarily installed in boreholes drilled from the heated drift.  Some tracer 
testing is being done as part of the Large Block Test (in a surface outcrop of TSw2 tuff), but 
these elements of the test cannot be considered in situ because of the lack of confining stress.  
Therefore, transport aspects of the codes used in this activity will be benchmarked primarily 
against laboratory-scale testing, most of which was described in other parts of the SCP.
4.2.2.4.5	Study 1.10.4.5:  Characterize the Effects of Introduced Materials on Water 
Chemistry in the Postemplacement Environment (New Study Added Since 
the SCP)
Background.  The objective of this study was to identify significant chemical modifications of 
the near-field environment from that which would be expected under geological conditions.  The 
modifications would be caused by the construction and operation of the repository and the 
postclosure conditions (e.g., radiation and thermal flux) as determined by repository design.  In 
addition to construction materials, a complete picture of the modified chemical and hydrologic 
system includes introduced air and water, the reintroduction of crushed tuff or muck rock (e.g., 
backfill), and the introduction of microbial populations.
Changes and Status.  This study did not exist in the SCP (DOE 1988).  It was developed from 
aspects of the near-field geochemistry study (1.10.4.1) that included the effects of introduced 
materials and radiation from the waste packages.  The original organization of the draft study 
plan included four activities.  When the draft study plan was revised, the material was organized 
differently to avoid confusion with the initial draft.  The initial drafts information was captured 
in the Site Design and Test Requirements Document (YMP 1995b).  The cross linkage of the 
original activities to the current activities is described below.
4.2.2.4.5.1	Activity 1.10.4.5.1:  Effect of Grout, Concrete, and Other Repository 
Materials on Water Composition (New Activity Added Since the SCP)
Background.  The objective of the activity was to conduct solubility, stability and reactivity 
experiments to determine the effect of grout, concrete, and other repository materials on water 
composition.
Changes and Status.  The objectives of this activity were moved to new Activities 1.10.4.5.5, 
1.10.4.5.6, 1.10.4.5.7, 1.10.4.5.8, and 1.10.4.5.10.
4.2.2.4.5.2	Activity 1.10.4.5.2:  Effects of Container and Borehole Liner Corrosion 
Products on Water Chemistry (New Activity Added Since the SCP)
Background.  The objective of the activity was to conduct solubility, stability and reactivity 
experiments to determine the effect of container and borehole liner corrosion products on water 
chemistry.
Changes and Status.  The objectives of this activity were moved to new Activities 1.10.4.5.6, 
1.10.4.5.7, and 1.10.4.5.10.
4.2.2.4.5.3	Activity 1.10.4.5.3:  Effects of Introduced Materials in the Presence of a 
Radiation Field (New Activity Added Since the SCP)
Background and SCP Plans.  The objective of this activity was to conduct the interaction 
experiments described in Activities 1.10.4.5.1 and 1.10.4.5.2 in the presence of a radiation field 
to identify potential effects on the predicted natural chemical reactions.
Changes and Status.  The objectives of this activity were moved to new Activity 1.10.4.5.7.
4.2.2.4.5.4	Activity 1.10.4.5.4:  Numerical Analysis and Modeling of Introduced 
Materials/Water Interaction (New Activity Added Since the SCP)
Background and SCP Plans.  The objective of this activity was to develop the necessary codes 
and to conduct predictions and simulations of repository performance with respect to introduced 
materials effects on the near-field environment.
Changes and Status.  The objectives of this activity were moved to new Activity 1.10.4.5.11.
4.2.2.4.5.5	Activity 1.10.4.5.5:  Integration: Program Planning; Identification, 
Characterization, and Screening of Materials; and Bibliographic 
Maintenance and Literature Review  
The objectives of this activity are to:
?	Prepare planning documents for the introduced materials study
?	Develop a list of materials that might be used in the repository (including locations, 
quantities, and concentrations)
?	Develop a chemical database regarding the materials
?	Rank the materials on the basis of aggressiveness under expected and certain unexpected 
repository conditions
?	Identify materials for which information is inadequate
?	Gather, synthesize, and evaluate data from the literature.  
These objectives are not necessarily sequential, and some products will be updated throughout 
the study. 
Changes and Status.  The identification and characterization of engineered materials was 
summarized in Chapter 7 of the Near-Field Altered Zone Models Report (CRWMS M&O 
1998p), and also in the Introduced (Man Made) Materials Synthesis Report (1993-1996) (Meike 
1996).  This report discussed the most abundant engineered materials in the near-field 
environment, including steel and concrete. Further work in this area was suspended for FY99 
pending definition of design features such as the ground support system and the emplacement 
drift invert.  For the Site Recommendation, a set of analyses was performed to support screening 
of features, events, and processes related to the potential effects of introduced materials.  These 
analyses, summarized by the EBS FEPs AMR (CRWMS M&O 2001d), show that the 
consequences of the presence and degradation of introduced materials are small, and can be 
mostly excluded from TSPA dose calculations.  If these effects were included in the TSPA, the 
impact on projected dose rates would be negligible.
4.2.2.4.5.6	Activity 1.10.4.5.6:  Solubility and Stability Experimental Studies at 
Ambient and Elevated Temperatures  
The objective of this activity is to conduct dissolution precipitation kinetics experiments to 
determine the sensitivity of the kinetics to temperature and fluid composition.  Stoichiometric 
and nonstoichiometric dissolution of introduced materials, in saturated and unsaturated 
environments, will be addressed.  The experiments are intended to identify the dissolution 
precipitation mechanisms, the effects of solid solution on rates of dissolution and precipitation, 
the solid reaction products, and the resulting water chemistry.  Solid, liquid, and gas phase 
stability will be addressed.
Changes and Status.  No progress has been made on this activity since 1998.
4.2.2.4.5.7	Activity 1.10.4.5.7:  Chemical Reactivity Stability Experimental Studies at 
Ambient and Elevated Temperatures  
The objective of this activity is to conduct chemical reactivity experiments on: 
?	Soluble products of introduced solid phases
?	Introduced organic and inorganic fluids
?	Introduced material interactions with water and vapor in the presence of a radiation field
?	Potential effects of introduced materials on predicted natural chemical reactions
?	Significance of natural mineral moderation (e.g., zeolites and buffering effects) on the 
aggressiveness of introduced materials.
Changes and Status.  Work in this area was discontinued in September 1998 and results on 
thermally and environmentally altered concretes were compiled and last reported in Section 5 of 
Volume 3 of the Engineered Materials Characterization Report (McCright 1998).
4.2.2.4.5.8	Activity 1.10.4.5.8:  Colloid Stability Experimental Studies at Ambient and 
Elevated Temperatures  
The objective of this activity is to identify introduced materials that can produce colloids and 
examine the nature and stability of the colloids.  This activity is intended to complement other 
work being conducted in Study 8.3.1.3.5.2 (Section 1.2.5 of this DPC). 
Changes and Status..Studies of introduced materials colloids are reported in AMRs Waste Form 
Colloid-Associated Concentration Limits: Abstraction and Summary (CRWMS M&O 2001e), 
and Colloid-Associated Radionuclide Concentration Limits:  ANL (CRWMS M&O 2001f).  This 
work is covered in Sections 1.2.5 and 5.6 of this report.
4.2.2.4.5.9	Activity 1.10.4.5.9:  Biodegradation Stability Experimental Studies at 
Ambient and Elevated Temperatures  
The objective of this activity is to identify and characterize microbes that might be introduced 
into the repository, and microbes (both native and introduced) that derive nourishment from 
introduced materials that could be brought into the repository.  The activity will identify 
introduced materials that will encourage microbe growth, identify chemical products of 
microbial degradation, and identify and evaluate the potential for introduction and growth of 
microbes from external sources.  This activity is intended to complement other work being 
conducted in Study 8.3.1.3.4.2 (Section 1.2.4 of this DPC).
With respect to microbe studies, the objectives have been to use the large block test and the drift 
scale test for migration and survival studies supported by appropriate laboratory experiments.  In 
this work, microbes were obtained from the large block test site and labeled by a method suitable 
to the application (Wilder 1997a; Wilder 1997b).  Tests were conducted to understand the 
longevity and thermal stability of the methods.  Suitable installation tools were designed and 
manufactured.  Care was taken that the methods and practices did not interfere with other tests.
As part of this work, drug-resistant and fluorescent-dye labeled bacteria have been developed to 
study microbial survival and migration, and preliminary longevity and thermal stability tests 
have been conducted.  Survival specimens have been placed at intervals along three vertical 
boreholes in the large block test to take advantage of the thermal gradient that will be present 
after the heater is powered.  Because of variations in placement and coupon design, the bacterial 
samples in each hole are expected to experience different, but relevant chemical environments.  
The migration experiments were initiated by extruding a microbe-inoculated gelatinous medium 
into the heater holes before the insertion of the heater. 
Changes and Status.  The drift scale test is continuing (early 2002) and test coupons are still in 
place.
4.2.2.4.5.10	Activity 1.10.4.5.10:  Historical analogs 
The objectives of this activity are to: 
?	Identify sites of interest as historical analogs to Yucca Mountain (determined from the 
materials list developed in Activity 1.10.4.5.5)
?	Collect samples from these sites
?	Analyze the samples for the information identified in Activity 1.10.4.5.5
?	Provide constraints for the experiments in Activities 1.10.4.5.7, 1.10.4.5.8, and 
1.10.4.5.9
?	Provide long-term data not obtainable from experiments for the development of the 
introduced material-rock-water interaction simulation activity (1.10.4.5.11).
Changes and Status.  Work on historical (anthropogenic) and natural analogues has continued 
since the needs were identified in 1996 (Meike 1995).  The current status is summarized in the 
Natural Analogue Synthesis Report (in progress).
4.2.2.4.5.11	Activity 1.10.4.5.11:  Computer Modeling and Code Development  
The objectives of this activity are to develop the necessary codes (if not otherwise available) and 
to conduct predictions and simulations of experiments, natural analogs, and repository 
performance with respect to introduced material effects on the near-field environment.  
Validation of developed models is included in this activity, which is complementary to Study 
8.3.4.2.4.1.
Changes and Status.  Software development has continued in this area since 1998. In 1998 the 
geochemical modeling code EQ3/6 (V 7.2b) was revised and qualified (CRWMS M&O 1998g).  
Since that time, work has been ongoing to modify the code to accommodate near-field chemical 
processes involving extensive evaporation.  In addition, a new chemical database (elevated-
temperature Pitzer model) was developed in 1999 for use with EQ3/6.  This database has been 
used for SR analyses and further refined since that time.  These tools have been used to evaluate 
the potential for changes in the chemical environment from degradation of introduced materials.


4.2.2.4.5.12	Application of Results (SCP Section 8.3.4.2.4.5)
Background and SCP Plans.  This section describes which information needs and 
investigations would be addressed using information from the activities preceding this section.
Changes and Status.  The Project plans to use the information in the manner described in this 
SCP section.
Schedule for Postclosure Waste Package Characteristics (SCP Section 8.3.4.2.5)
Background and SCP Plans.  This section of the SCP provides a schedule for addressing 
information needs and studies for postclosure waste package characteristics.
Changes and Status.  The schedule for obtaining information for many key activities has been 
revised as described in the semiannual progress reports.  This method of documenting changes is 
consistent with the text in the SCP (DOE 1988) section.  The schedules presented in the SCP 
were based on the DOEs June 1987 Mission Plan Amendment (DOE 1987a; 1987b), which 
assumed the license application for the repository would be submitted to the NRC in 1995.  
In 1989, the Secretary of Energy assessed the progress and needs of the site characterization 
project, and a new schedule was adopted that planned for the submittal of the license application 
in FY 2002.  However, recent modification of the Programs schedule during this reporting 
period, deferred the site recommendation to the President until early 2002, and, consequently, 
deferred the submittal of the license application.  The DOE is currently evaluating the schedule 
for the submittal of the license application to the NRC, if the site is recommended and approved.  
The evaluation is considering the latest requirements of NRCs proposed 10 CFR Part 63 
(64 FR 8640), recent interactions with the NRC, and the budgetary constraints from 
Congressional appropriations.
4.2.3	Issue Resolution Strategy for Issue 2.6:  Have the Characteristics of the Waste 
Packages Been Adequately Established to (a) Show Compliance With the 
Preclosure Design Criteria of 10 CFR 60.135 and (b) Provide Information for the 
Resolution of the Performance Issues? (SCP Section 8.3.4.3)
Background and SCP Plans.  This section provided the approach to resolving the issue of 
compliance with preclosure design criteria of 10 CFR 60.135.  Figure 8.3.4.3-1 (DOE 1988) 
provided a logic diagram of the process planned to address the issue.  Table 8.3.4.3-1 
(DOE 1988) listed the major preclosure functions or characteristics derived from the regulatory 
criteria for the waste packages.
Changes and Status.  The general approach to resolving Issue 2.6 still follows the description in 
the SCP, but changes have occurred.  The requirements documents follow the same hierarchy 
described in Information Need 4.4.4 (see Section 2.3.16).  Development of waste packages is 
now governed by the Waste Package Design Methodology Report (Brownson 2001).  There have 
also been several changes to the quantitative performance goals given in the SCP (DOE 1988, 
Table 8.3.4.3-1).  The performance objective used for the repository during normal operations is 
that for Category 1 design basis events, the annual dose to any real member of the public located 
beyond the boundary of the site shall not exceed a TEDE of 25 mrem.  This requirement is 
imposed on the waste packages through total system performance (CRWMS M&O 1999a,

pp. 1319).  Legibility of the waste package identifiers to the end of the period of retrievability is 
still a requirement (YMP 1994c, Section 3.7.1.2, p. 52).  Current waste package designs 
(DOE 1998a, Volume 2, Section 5) for commercial spent nuclear fuel will accommodate 
100 percent of the commercial spent nuclear fuel waste forms planned for storage at the 
repository.  The goal for retrieval is that all waste should be retrievable at any time for up to 
100 years after waste emplacement operations have begun, to support retrieval operations for up 
to 34 years, and to support closure operations for up to 10 years (YMP 1994c).  This change was 
made because the Project has pursued a more focused approach that will include fewer studies 
than previously planned.  The longer retrievability period will allow a longer period of 
performance confirmation and, therefore, increased confidence that the more limited scope of 
site characterization has provided adequate understanding of predicted site and repository 
performance (see footnote 1, page I-1).
4.2.3.1	Information Need 2.6.1:  Design Information Needed to Comply With Preclosure 
Criteria From 10 CFR 60.135(b) for Materials, Handling, and Identification of 
Waste Packages (SCP Section 8.3.4.3.1)
Background and SCP Plans.  This information need provided the general approach to obtaining 
design information needed to comply with preclosure criteria from 10 CFR 60.135(b).  The 
section listed and described four parameters to be addressed.
Changes and Status.  The design criteria of 10 CFR 60.135(b)(1) through (4) concern the types 
of materials that may be used in a waste package, design for handling, and unique identification.  
These criteria are still in effect and are being considered.  Commercial spent nuclear fuel and 
high-level waste glass are in compliance with these requirements (YMP 1994c, Section 3.7.11, 
pp. 51 and 52).  Additional work is in progress on other waste forms.  The approach described in 
the information need is consistent with the present Program approach (see footnote 1, page I-1).
4.2.3.1.1	Application of Results (SCP Section 8.3.4.3.1.1)
Background and SCP Plans.  This section described very briefly how the results of analyses 
performed for the associated information need would be used.
Changes and Status.  The application of results indicated in the SCP is consistent with the 
current program approach.
4.2.3.2	Information Need 2.6.2:  Design Information Needed to Comply With Preclosure 
Criteria from 10 CFR 60.135(c) for Waste Forms (SCP Section 8.3.4.3.2)
Background and SCP Plans.  This information need was to obtain design information to 
comply with preclosure criteria from 10 CFR 60.135(c) for the waste form.  The section listed 
the specific regulatory-based parameters to be addressed and described the planned logic.  Also 
mentioned was a requirement that high-level waste be placed in sealed containers.
Changes and Status.  The approach being taken to address this information need is consistent 
with the approach described in the SCP.  The design criteria from 10 CFR 60.135(c) address the 
solidification and consolidation of waste forms and the presence of combustible materials in 
waste forms.  Analysis of each waste form to demonstrate compliance is still planned. 

Commercial spent nuclear fuel and defense high-level waste are in compliance, but other waste 
forms still require analysis.  Plans to use sealed containers for each waste form or canistered 
waste form are still in effect.
4.2.3.2.1	Application of Results (SCP Section 8.3.4.3.2.1)
Background and SCP Plans.  This section briefly explained how information obtained to 
address the associated information need would be used.
Changes and Status.  The application of results indicated in the SCP is consistent with the 
current Program approach.
4.2.3.3	Information Need 2.6.3:  Waste Acceptance Specifications (SCP 
Section 8.3.4.3.3)
Background and SCP Plans.  This information need was to develop specifications for 
acceptance at the repository of various waste forms.  The section listed the parameters involved, 
which are acceptance specifications for unreprocessed spent fuel, West Valley high-level waste, 
and DOE defense high-level waste.  The section provided a basic logic planned to be used in 
addressing the information need.
Changes and Status.  The present program approach is consistent with the approach presented 
in the information need.  In addition to the waste types described in the information need, 
acceptance specifications will need to be developed for DOE-owned spent fuel, which has been 
added to the Program baseline since the SCP was written.
4.2.3.3.1	Application of Results (SCP Section 8.3.4.3.3.1)
Background and SCP Plans.  This section briefly explained how information obtained to 
address the associated information need would be used.
Changes and Status.  The application of results indicated in the SCP is consistent with the 
current program approach.
4.2.3.4	Schedule for Preclosure Waste Package Characteristics (SCP Section 8.3.4.3.4)
Background and SCP Plans.  This section of the SCP provided a schedule for addressing 
information needs and studies for preclosure waste package characteristics.
Changes and Status.  The schedule for obtaining information for many key activities has been 
revised as described in the semiannual progress reports.  This method of documenting changes is 
consistent with the text in the SCP (DOE 1988) section.  The schedules presented in the SCP 
(DOE 1988) were based on the DOEs June 1987 Mission Plan Amendment (DOE 1987a; 
1987b), which assumed the license application for the repository would be submitted to the NRC 
in 1995.  In 1989, the Secretary of Energy assessed the progress and needs of the site 
characterization project, and a new schedule was adopted that planned for the submittal of the 
license application in FY 2002.  The Program Plan (DOE 1996a) supporting the FY 2002 
submittal contains a schedule for accomplishment of major Program activities.  However, recent

modification of the Programs schedule during this reporting period, deferred the site 
recommendation to the President until early 2002, and, consequently, deferred the submittal of 
the license application.  The DOE is currently evaluating the schedule for the submittal of the 
license application to the NRC, if the site is recommended and approved.  The evaluation is 
considering the latest requirements of NRCs proposed 10 CFR Part 63 (64 FR 8640680), recent 
interactions with the NRC, and the budgetary constraints from Congressional appropriations.
4.2.4	Issue Resolution Strategy for Issue 4.3:  Are the Waste Package Production 
Technologies Adequately Established for the Resolution of the Performance Issues? 
(SCP Section 8.3.4.4)
Background and SCP Plans.  This section provided the approach to resolving the issue of 
whether waste package production technologies are adequately established.  The approach was 
shown graphically in Figure 8.3.4.4-1 (DOE 1988).
Changes and Status.  This section and its subsections discuss three design activities intended to 
show that waste packages can be produced with reasonably available technology.  These 
activities are equally applicable to both the SCP (DOE 1988) design and the current design.  
Waste package requirements are specified in the same document hierarchy described above for 
Issue 2.6 (SCP Section 8.3.4.3).  Formal trade-off studies described in the SCP, in which several 
candidate approaches are ranked against selection criteria, have not been performed and are not 
planned because industrial experience with production of large, thick-walled vessels is 
considered sufficient to allow selection of suitable technologies.  Instead, experience from 
production of thick-walled vessels is used to choose one or sometimes two approaches for further 
study.  Tests on full-scale prototypes have not been performed but are still planned.  Mock ups 
have been produced that have full-scale diameter but reduced length, because much of the length 
of the cylindrical part of the containment barriers are unnecessary in demonstrating fabricability.  
The logic diagram for resolution of Issue 4.3 (DOE 1988, Figure 8.3.4.4-1) is still applicable 
with the following modifications:  The branch at the bottom of the diamond labeled Is viable 
process option available? should be removed; testing has been performed.  As described 
previously, the step Select fabrication process has been documented in the fabrication process 
reports.
4.2.4.1	Information Need 4.3.1:  Identification and Evaluation of Production 
Technologies for Fabrication, Closure, and Inspection of the Waste Package 
(SCP Section 8.3.4.4.1)
Background and SCP Plans.  This information need was to provide general information 
regarding identification and evaluation of waste package fabrication, closure, and inspection 
technologies.  This section does not describe a specific strategy or process.
Changes and Status.  The section is still applicable as written.
4.2.4.1.1	Design Activity 4.3.1.1:  Waste Package Fabrication Process Development 
(SCP Section 8.3.4.4.1.1
Background and SCP Plans.  This design activity was to determine the processes to be used in 
fabricating the nonwaste form waste package components.  The section listed parameters to be 
addressed and described planned processes.
Changes and Status.  The present Program approach is different from the approach presented in 
the design activity, including the list of parameters.  Because of their multiple containment 
barriers, fabrication of waste packages to current designs is more complex than fabrication to the 
SCP design (as discussed in this design activity).  Nevertheless, the processes identified are 
applicable to both designs.  As noted in the discussion for Issue 4.3 (SCP (DOE 1988) 
Section 8.3.4.4), selection criteria and candidate processes have been formally developed.  To 
date, the production of materials, forming and joining, heat treating, and nondestructive 
evaluation have been considered and tested.  Packaging, shipping, and storage as discussed in the 
SCP will be considered later.
4.2.4.1.2	Design Activity 4.3.1.2:  Waste Package Closure Process Development (SCP 
Section 8.3.4.4.1.2)
Background and SCP Plans.  This activity was to determine the final closure process for waste 
package containers.  This section listed parameters to be addressed and described the closure 
process.
Changes and Status.  The present Program approach differs from the approach presented in the 
design activity.  Closure is more complicated for a multi-barrier package than a single-barrier 
package.  The greater thicknesses specified in current designs also contribute to the complexity 
of closure operations.  As discussed previously for Issue 4.3 (DOE 1988, Section 8.3.4.4), 
selection criteria and candidate processes have been formally developed.  Plans still state that 
closure will occur in a hot cell by remote control.  Qualification of a welding process by 
monitoring process variables as discussed in the SCP is not considered practical and will not be 
pursued.  Quantification of the weld will be by ASME (American Society of Mechanical 
Engineers) code  Each closure weld will be inspected.
4.2.4.1.3	Design Activity 4.3.1.3:  Waste Package Closure Inspection Process 
Development (SCP Section 8.3.4.4.1.3)
Background and SCP Plans.  This activity was to determine the process to be used in 
inspecting the final closure of the waste package containers.  The section listed six parameters to 
be addressed and briefly described the planned process.
Changes and Status.  The present Program approach differs from the approach presented in the 
design activity.  Closure inspection is as important now as when the SCP was written.  As 
discussed previously for Issue 4.3 (DOE 1988, Section 8.3.4.4), selection criteria and candidate 
processes have been formally developed and development is not planned.  Current plans are that 
each closure weld will be visually and surface inspected and ultrasonically tested, both by remote 
means.  Demonstration of these techniques has been proven on mock ups.

4.2.4.1.4	Application of Results (SCP Section 8.3.4.4.1.4)
Background and SCP Plans.  This section briefly described how information from the study 
would be used.
Changes and Status.  The application of results indicated in the SCP is consistent with the 
current Program approach.
4.2.4.2	Schedule for Waste Package Production Technologies (SCP Section 8.3.4.4.2)
Background and SCP Plans.  This section of the SCP provides a schedule for addressing design 
activities for waste package production technologies.
Changes and Status.  The schedule for obtaining information for many key activities has been 
revised as described in the semiannual progress reports.  This method of documenting changes is 
consistent with the text in the SCP (DOE 1988) section.  The schedules presented in the 1988 
SCP were based on the DOEs June 1987 Mission Plan Amendment (DOE 1987a; 1987b), which 
assumed the license application for the repository would be submitted to the NRC in 1995.  
In 1989, the Secretary of Energy assessed the progress and needs of the site characterization 
project, and a new schedule was adopted that planned for the submittal of the license application 
in FY 2002.  However, recent modification of the Programs schedule during this reporting 
period, deferred the site recommendation to the President until early 2002, and, consequently, 
deferred the submittal of the license application.  The DOE is currently evaluating the schedule 
for the submittal of the license application to the NRC, if the site is recommended and approved.  
The evaluation is considering the latest requirements of NRCs proposed 10 CFR Part 63 
(64 FR 8640), recent interactions with the NRC, and the budgetary constraints from 
Congressional appropriations.


5.	PERFORMANCE ASSESSMENT PROGRAM (SCP SECTION 8.3.5)
This section summarizes the performance assessment plans in the SCP (DOE 1988), changes in 
the performance assessment program from the SCP, and the current status of that program.  
Performance assessment technology exists to evaluate both the preclosure radiological safety and 
the postclosure waste isolation performance of the MGR, although considerable improvements in 
that technology are expected as new site data and laboratory research results become available.
The following factors have influenced and changed the performance assessment program from 
that planned in the SCP:
? Changes in the regulatory framework, including the definition of design basis events for 
preclosure radiological safety and a potential radiological risk-based standard for 
postclosure performance (proposed 10 CFR 63 [64 FR 8640]; National Research 
Council 1995)
? The planned replacement of detailed technical guidelines of 10 CFR 960 by new system 
guidelines with respect to both preclosure and postclosure higher level findings and 
NRC siting criteria (64 FR 67054)
? New understanding of the site, including surface water infiltration, fracture flow, 
thermal-hydrological processes, and the importance of the saturated zone (DOE 1996a)
? Waste package and repository design changes, principally the change to high thermal 
loading and from vertical borehole emplacement of small thin-walled waste packages to 
horizontal in-drift emplacement of large double-walled waste packages (CRWMS 
M&O 1996g)
? The DOEs waste containment and isolation strategy (Younker 1996b), updated as the 
DOEs repository safety strategy (YMP 1998c) and issued in January 1998
? The DOEs selection of the repository design to be used as the basis for development of 
the site recommendation documentation.  This design concept will be developed for use 
in evaluating the site and preparing the license application if the site is suitable 
(CRWMS M&O 1999e).
The factors listed above are reflected in the following:
? The definition of design basis accidents for preclosure performance assessments as 
described in the Mined Geologic Disposal System Advanced Conceptual Design Report 
(CRWMS M&O 1996g, Volume II, Section 10) and in Preliminary Mined Geologic 
Disposal System Hazards Analysis (CRWMS M&O 1996j), the identification of internal 
and external hazards (CRWMS M&O 2000n and CRWMS M&O 2000o), and the 
preliminary safety assessment of MGR operations in the preclosure period as described 
in the Preliminary Preclosure Safety Assessment for Monitored Geologic Repository Site 
Recommendation (BSC 2001g).
? The need to revise the approach for potential waste package retrieval as described in the 
Mined Geologic Disposal System Advanced Conceptual Design Report (CRWMS 
M&O 1996g, Volume II, Section 9), and the identification of scenarios that may require 
retrieval including retrieval options as described in the Retrievability Strategy Report 
(CRWMS M&O 1998h).
? Increased integration of abstractions of detailed process models for postclosure 
performance assessments of the overall repository system (CRWMS M&O 1996k; 
CRWMS M&O 1996l; DOE 1998a)
? Waste package materials being tested, including corrosion-allowance and corrosion-
resistant materials, the consideration of different environmental conditions, and related 
model development efforts (CRWMS M&O 1996g, Volume III, Section 4; CRWMS 
M&O 1998c; McCright 1995; McCright 1998; Van Konynenburg et al. 1995)
? Minor changes in the waste form testing and related model development (Stout and 
Leider 1998)
? The need for remote operations for performance confirmation and shift of some 
activities from the site characterization phase to the post-license application period 
(CRWMS M&O 1996m; CRWMS M&O 1997p)
? The availability of a suite of mathematical models and computer codes for preclosure 
and postclosure performance assessments, with improvements expected as new site and 
laboratory data become available (see Section 1 of this report).
Summary descriptions of the status and changes for each of the SCP (DOE 1988) performance 
assessment sections follow.
5.1	PRECLOSURE PERFORMANCE ASSESSMENT (SCP SECTIONS 8.3.5.1, 8.3.5.3, 
8.3.5.4, AND 8.3.5.5)
The four preclosure performance assessment sections of the SCP (DOE 1988, Sections 8.3.5.1, 
8.3.5.3, 8.3.5.4, and 8.3.5.5) are addressed together because of their interdependence and because 
proposed NRC regulations may eliminate some of the distinctions with respect to the required 
evaluations.  Following are summaries of the current applicability of each of these preclosure 
performance assessment SCP sections and their related information needs.
The strategy for addressing projected releases of radioactive materials to onsite and offsite areas 
and the resulting radiation exposure to the general public and workers during the preclosure 
phase is addressed by SCP Section 8.3.5.1 Strategy for Preclosure Performance Assessment.  
This section summarizes the strategy for the other three preclosure performance assessment SCP 
Sections (8.3.5.3, 8.3.5.4, and 8.3.5.5); these sections address the specific analyses required for 
predicting preclosure radiological exposures of workers and the public from design basis events, 
including routine repository operation.
5.1.1	Strategy for Preclosure Performance Assessment (SCP Section 8.3.5.1)
Background and SCP Plans.  SCP Section 8.3.5.1 addresses the development of the preclosure 
performance assessment strategy for resolving Key Issue 2.  This issue asks whether the 
projected releases of radioactive materials to restricted and unrestricted areas and the resulting 
radiation exposures of the general public and workers during repository operation, closure, and 
decommissioning at Yucca Mountain would meet the applicable requirements set forth in 
10 CFR 20, 10 CFR 60, 10 CFR 960, and 40 CFR 191.
The resolution of this issue centered around the development of a preclosure risk assessment 
methodology which would have consisted of:
? Developing the methods, mathematical models/computer codes, and databases for 
assessing both radiological and nonradiological risks to the workers and general public 
in the preclosure phase
? Identifying the structures, systems and components important to preclosure radiological 
safety for the Q-List (YMP 2001b)
? Recommending preventative and mitigative measures to the MGR design
? Demonstrating compliance with regulatory requirements (10 CFR 20, 10 CFR 60, 
10 CFR 960, 40 CFR 191, and DOE orders)
? Informing the public on preclosure repository safety.
The development and implementation of the preclosure risk assessment methodology was to 
have been led by a working group of all three repository programs (salt, basalt and tuff) existing 
before the issuance of the SCP; the cancellation of the salt and basalt repository programs by the 
1987 amendments to the NWPA eliminated the coordination need.
Changes and Status.  The preclosure risk assessment methodology program and working group 
described in the SCP (DOE 1988) no longer exist as formal entities.  The license application will 
consider regulatory changes with respect to the definition of design basis events.  Where 
possible, the methodologies to predict the consequences of preclosure radioactive releases are 
being taken from previously successful license applications and environmental impact 
statements.
Since the SCP (DOE 1988) was written, the NRC has proposed to refer to normal and accident 
events as design basis events.  The term design basis event is introduced in the proposed 
10 CFR 63 (64 FR 8640) rule change and is defined as follows:
? Those natural and human-induced events that are expected to occur one or more times 
before permanent closure of the geologic repository operations area
? Other natural and man-induced events that have at least one chance in 10,000 of 
occurring before permanent closure of the geologic repository.
Design basis events meeting the first definition are referred to as frequency Category 1 design 
basis events, and those meeting the second definition are classified as frequency Category 2 
design basis events.  Using these definitions, Public Radiological Exposures - Normal 
Conditions (SCP Section 8.3.5.3) and Worker Radiological Safety - Normal Conditions (SCP 
Section 8.3.5.4) are Category 1 design basis events, but Accidental Radiological Releases 
(SCP Section 8.3.5.5) may be Category 1 or Category 2 design basis events.  As a result, normal 
exposures (public and worker) and accidental exposures are being grouped together (with similar 
models for a given category of design basis events) and radiation dose limits vary depending on 
the frequency category of the design basis event.
In past analyses, the computer codes GENII, MACCS, MCNP, and DORT-TORT have been 
used.  A new biosphere radiological assessment model is being developed that will support the 
postclosure radiation dose estimation.  Some of the parameters developed for that purpose will 
have the capability to evaluate long-term bio-accumulation impacts of preclosure radioactive 
releases.
5.1.2	Public Radiological Exposures:  Normal Conditions (SCP Section 8.3.5.3)
Background and SCP Plans.  SCP, Section 8.3.5.3 (DOE 1988), addresses Issue 2.1, which 
asks whether during repository operation, closure, and decommissioning the expected average 
radiation dose received by members of the public within any highly populated area will be less 
than a small fraction of the allowable limits and the expected radiation dose received by any 
member of the public in an offsite area will be less than the allowable limits as required by 
10 CFR 60.111, 40 CFR 191 Subpart A, and 10 CFR 20.  The first part refers to the total 
population dose (in man-rem exposure) in a highly populated area as defined by 10 CFR 960.2, 
while the second part refers to the radiation dose of individuals in the site vicinity.  Assessments 
were to be conducted periodically as the MGR design progresses in order to provide feedback to 
the design.  The SCP approach to resolving Issue 2.4 is addressed by one information need (see 
footnote 1, page I-1).
Information Need 2.1.1:  Site and design information needed to assess preclosure radiological 
safety (SCP Section 8.3.5.3.1).  The SCP lists the following three performance assessment 
activities to fill this information need:
? Performance Assessment Activity 2.1.1.1:  Refinement of Site Data Parameters 
Required for Issue 2.1.  The objective of this activity is to refine the population, 
agricultural, surface water, meteorological, host rock, and offsite nuclear installation 
data needed for determining preclosure radiological exposures to members of the public 
resulting from normal repository operations.
? Performance Assessment Activity 2.1.1.2:  Development of Performance Assessment 
Activities Through the Preclosure Assessment Risk Methodology Program.  The 
objective of this activity is to benefit from the performance assessment methods 
development efforts for the preclosure risk assessment methodology program.  
A secondary objective is to use the information developed in this activity to assist in 
refining the site parameters list for SCP Issue 2.1 (Performance Assessment 
Activity 2.1.1.1).
? Performance Assessment Activity 2.1.1.3:  Advanced Conceptual Design Assessment of 
the Public Radiological Safety During the Normal Operations of the Potential Yucca 
Mountain Repository.  The objective of this activity is to perform a public radiological 
safety assessment of the advanced conceptual design of a potential Yucca Mountain 
repository.  Secondary objectives are to provide information for the refinement of the 
site data parameters list for SCP Issue 2.1 (Performance Assessment Activity 2.1.1.1) 
and to provide feedback to the preclosure risk assessment methodology program for 
future methods development activities (Performance Assessment Activity 2.1.1.2).
Changes and Status.  Efforts are in progress and will continue to demonstrate compliance with 
proposed 10 CFR 63 (64 FR 8640) and 10 CFR 20.  The final dose limits in 40 CFR 197 (66 FR 
32074) that became effective on July 13, 2001, supersede 40 CFR 191 dose limits for the Yucca 
Mountain site.  Site data are being collected in the environmental, geological, and hydrological 
site programs.  Atmospheric dispersion of potential radionuclide releases was modeled to assess 
the radiological effects of inhalation, using Regulatory Guide 1.25 for guidance.  The site 
program started a review of biosphere radiological assessment models for evaluating long-term 
bioaccumulation impacts of preclosure radioactive releases.  The preliminary hazards analysis 
that identified a comprehensive list of possible events, both internal and external initiating 
events, has been revised and reissued as internal and external hazards analyses (CRWMS 
M&O 2000n and CRWMS M&O 2000o).  The identified events have been screened for 
relevancy to preclosure radioactive releases at the potential repository.  The Preliminary 
Preclosure Safety Assessment for Monitored Geologic Repository Site Recommendation (BSC 
2001g) documents the preliminary safety assessment of MGR operations in the preclosure period 
including identification of facility hazards and their potential for initiating events, identification 
of MGR design basis events, evaluation of design basis events occurrence frequencies and 
consequences, and identification of those structures, systems, and components important to 
safety.  Design basis event analyses will continue for the surface and subsurface portions of the 
potential repository to evaluate whether the consequences from candidate design basis events are 
within regulatory limits.
5.1.3	Worker Radiological Safety:  Normal Conditions (SCP Section 8.3.5.4)
Background and SCP Plans.  SCP, Section 8.3.5.4 (DOE 1988), addresses Issue 2.2, which 
asks whether the repository can be designed, constructed, operated, closed, and decommissioned 
in a manner that ensures the preclosure radiological safety of workers under normal operations as 
required by 10 CFR 60.111 (10 CFR 63.204) and 10 CFR 20.
Resolution of this issue assumed that the MGR would be designed to limit the normal radiation 
doses to workers during construction, operation, closure, and decommissioning of the repository 
to less than the limits specified by 10 CFR 20.  An iterative process of analyses and design were 
planned to achieve radiation doses as low as reasonably achievable.  The SCP approach to 
resolving Issue 2.2 is addressed by two information needs.
? Information Need 2.2.1:  Determination of radiation environment in surface and 
subsurface facilities due to natural and manmade radioactivity (SCP Section 8.3.5.4.1).
? Information Need 2.2.2:  Determination that projected worker exposures and exposure 
conditions under normal conditions meet applicable requirements (SCP 
Section 8.3.5.4.2).
The SCP lists the following five performance assessment activities to fill these two information 
needs:
? Performance Assessment Activities 2.2.1.1 and 2.2.2.1:  Refinement of Site Data 
Parameters Required for Issue 2.2.  The objectives of these two activities, respectively, 
are to refine the data needed on the subsurface radiation environment due to natural and 
man-made radioactivity and the meteorological, host rock, and groundwater data needed 
for determining radiological exposures to workers resulting from normal repository 
operations.
? Performance Assessment Activities 2.2.1.2 and 2.2.2.3:  Advanced Conceptual Design 
Assessment of the Worker Radiological Safety During Normal Operations of the 
Potential Yucca Mountain Repository.  The objectives of these activities are to perform 
a worker radiological safety assessment of the advanced conceptual design for a 
potential Yucca Mountain repository considering natural and man-made sources of 
radioactivity.  Secondary objectives are to provide information for the refinement of the 
site data parameters list for SCP Issue 2.2 (Performance Assessment Activities 2.2.1.1 
and 2.2.2.1) and to provide feedback to the preclosure risk assessment methodology 
program for future methods development activities (Performance Assessment 
Activity 2.2.2.2).
? Performance Assessment Activity 2.2.2.2:  Development of Performance Assessment 
Activities through the Preclosure Risk Assessment Methodology Program.  The 
objective of this activity is the development of performance assessment activities to 
benefit from the preclosure risk assessment methodology program.  A secondary 
objective is to use the information developed in this activity to assist in refining the site 
data parameters list for SCP Issue 2.2 (Performance Assessment Activities 2.2.1.1 and 
2.2.2.1).
Changes and Status.  Site data for these analyses are being collected in the environmental, 
geological, and hydrological site programs.  Radiation doses are being calculated for candidate 
Category 1 design basis events.
5.1.4	Accidental Radiological Releases (SCP Section 8.3.5.5)
Background and SCP Plans.  SCP, Section 8.3.5.5 (DOE 1988), addresses Issue 2.3, which 
asks whether the repository can be designed, constructed, operated, closed, and decommissioned 
in such a way that credible accidents do not result in projected radiological exposures of the 
general public at the nearest boundary of the offsite area, or workers in the onsite area, in excess 
of applicable limiting values.
Resolution of this issue would have included an analysis of the adequacy of structures, systems 
and components provided for the prevention of accidents and mitigation of consequences.  These 
analyses were to be presented to the NRC in the Safety Analysis Report of the license application 
and regulatory closure would occur with the NRC issuing a favorable Safety Evaluation Report 
on the license application.  The SCP approach to resolving Issue 2.3 is addressed by two 
information needs.
? Information Need 2.3.1:  Determination of credible accident sequences and their 
respective frequencies applicable to the repository (SCP Section 8.3.5.5.1)
? Information Need 2.3.2:  Determination of the predicted releases of radioactive material 
and projected public and worker exposures under accident conditions and that these 
exposures meet applicable requirements (SCP Section 8.3.5.5.2).
The SCP lists the following seven performance assessment activities to fill these two information 
needs:
? Performance Assessment Activities 2.3.1.1 and 2.3.2.1:  Refinement of Site Data 
Parameters Required for Issue 2.3.  The objective of these activities is to refine the 
population, agricultural, surface-water, and meteorological data needed for determining 
credible accident sequences and their respective frequencies, for developing candidate 
design basis accidents, and for determining preclosure radiological exposures to 
members of the public and to workers as a result of credible accidental radiological 
releases.
? Performance Assessment Activity 2.3.1.2:  Determination of Credible Accident 
Sequences and their Frequencies Applicable to the Potential Yucca Mountain 
Repository.  The objective of this activity is to develop a comprehensive list of accidents 
that are both credible and applicable to a potential Yucca Mountain repository.
? Performance Assessment Activity 2.3.1.3:  Development of Candidate Design Basis 
Accidents for the Potential Yucca Mountain Repository.  The objective of this activity is 
to develop a set of candidate design basis accidents to be analyzed as part of the total 
safety analysis.
? Performance Assessment Activity 2.3.2.2:  Consequence Analyses of Credible 
Accidents at the Potential Yucca Mountain Repository.  The objective of this activity is 
to determine the consequences of credible accidents in terms of radiation doses to the 
essential repository workers and the public.
? Performance Assessment Activity 2.3.2.3:  Sensitivity and Importance Analyses of 
Credible Accidents at the Potential Yucca Mountain Repository.  The objectives of this 
activity are to quantify uncertainties and sensitivities in the accident risk assessment and 
to establish importance rankings for systems, structures, and components of a potential 
Yucca Mountain repository with respect to radiological safety.
? Performance Assessment Activity 2.3.2.4:  Documentation of Results of Safety Analyses 
and Comparison to Applicable Limiting Values.  The objectives of this activity are to 
produce documentation of the results of the accident risk assessment in the necessary 
format and to make comparisons of the results to applicable limiting values.  This 
activity will complete the resolution of SCP Issue 2.3 at the end of the license 
application design.
Changes and Status.  Site data for these analyses are being collected in the environmental, 
geological, and hydrological site programs.  Candidate Category 2 events were defined in the 
Preliminary Mined Geologic Disposal System Hazards Analysis report (CRWMS M&O 1996j) 
considering the 10 CFR 60 (see footnote 1, page I-1) rule change.  The candidate events were 
grouped by potential radioactive release magnitude or consequence severity to identify the 
bounding design basis event in each group.  Design basis event analyses will continue for the 
surface and subsurface portions of the potential repository to evaluate whether the consequences 
from candidate design basis events are within regulatory limits.
5.2	WASTE RETRIEVABILITY (SCP SECTION 8.3.5.2)
Background and SCP Plans.  SCP, Section 8.3.5.2 (DOE 1988), addresses Issue 2.4, which 
asks whether the repository can be designed constructed, operated, closed, and decommissioned 
so that the option of waste retrieval would be preserved as required by 10 CFR 60.111.
The requirement to preserve the option to retrieve, as defined in Section 122 of the NWPA, is 
necessary to protect the public health and safety or the environment (according to the SCP, the 
decision to retrieve for this reason will be made as a result of the performance confirmation 
program) or to recover economically valuable contents of the spent fuel..
The retrieval position and concepts presented in the SCP (DOE 1988) and supporting documents 
are based on vertical borehole emplacement of small waste packages at an areal thermal loading 
of 57 kW/acre.  No further work was done with respect to retrievability until the development of 
the current MGR advanced conceptual design (CRWMS M&O 1996g, Volume II, Section 9.2).
The SCP approach to resolving Issue 2.4 is addressed by six information needs.  The current 
applicability of each information need is summarized below.
? Information Need 2.4.1:  Site and design data required to support retrieval (DOE 1988, 
Section 8.3.5.2.1).  Site data are being collected in the site program and retrieval design 
data will be developed after design requirements for the preliminary MGR design 
(which follows the advanced conceptual design) have been formulated by the FY 1997 
Retrievability Strategy Report (CRWMS M&O 1998h).  This study concludes that the 
retrievability option will be demonstrated by proof of principle testing before 
submittal of the license application to receive and possess waste.
? Information Need 2.4.2:  Determination that access to the waste emplacement boreholes 
can be provided throughout the retrieval period for normal and credible abnormal 
conditions (DOE 1988, Section 8.3.5.2.2).  This need still exists because it addresses 
access from the surface facilities to the emplacement locations, although borehole 
emplacement is not planned.  To provide access, backfill would not be placed in any 
area underground until after the need to maintain the retrievability option in that area 
will cease.  The Retrieval Conditions Evaluation report (CRWMS M&O 1995e, 
Section 6.1) evaluated temperatures that would exist during potential retrieval 
operations.  Ventilation to reduce temperatures and/or remotely operated retrieval 
equipment will be necessary.  The Retrievability Strategy Report (CRWMS 
M&O 1998h, Section 8) calls for sufficient ventilation to cool the drifts where waste is 
to be retrieved, such that under normal conditions the emplacement equipment can be 
used.  Additionally, the report requires that to build an acceptable level of confidence 
that retrieval is possible, proof-of-principle demonstrations must be completed and 
documented before submittal of the license application to receive and possess waste.  
Those components for which adequate demonstration cannot be provided through 
supplier performance data will be identified by a Test and Evaluation analysis and tested 
to provide reasonable assurance that the planned retrieval method will function under 
abnormal conditions.  Under the current repository design and operational concept, the 
need for proof-of-principle data and tests for retrieval methods and equipment will be 
met by the data and test required to show that access to and movement of waste 
packages will be assured during the operational period.  No specific demonstration for 
retrieval is required.
? Information Need 2.4.3:  Determination that access to the waste packages can be 
provided throughout the retrieval period for normal and credible abnormal conditions 
(DOE 1988, Section 8.3.5.2.3).  This need, which addresses emplacement borehole 
design, does not exist for the current advanced conceptual design.  The Retrievability 
Strategy Report (CRWMS M&O 1998h, Section 8.3) recommends that data on ground 
support response from the Drift Scale Tests should be incorporated into the drift design 
methodology.  The intent of this recommendation is to ensure that the ground support 
will be sufficiently robust to support the retrievability period of 100 years.
? Additionally, this report reiterates the Mined Geologic Disposal System Requirements 
Document (YMP 1998b, Section 3.2.H), which states that the MGR shall be designed to 
support repository construction for the 6 years prior to waste emplacement, initiation of 
retrieval at any time up to 100 years after waste emplacement operations have begun, 
retrieval operations for up to 34 years, and closure operations for up to 10 years.  This 
requirement is intended to reinforce the needed design life of the ground support system.
? Information Need 2.4.4:  Determination that the waste can be removed from the 
emplacement boreholes throughout the retrieval period for normal and credible 
abnormal conditions (DOE 1988, Section 8.3.5.2.4).  This need, which addresses waste 
package and equipment design for retrieval from boreholes, still exists, although 
borehole emplacement is not planned.  Instead, this need will be considered in the 
preliminary MGR design after its design requirements for retrievability have been 
formulated.  The Retrievability Strategy Report (CRWMS M&O 1998h, Section 8) 
assumes the Viability Assessment design of large waste packages placed horizontally in 
long emplacement drifts and recommends specific design needs such as ventilation and 
other design requirements and makes recommendations on how to prove that the 
retrievability requirement can be varied.  This report digresses from the SCP in that the 
actual equipment prototype demonstrations would be delayed to just before requesting 
the license revision to receive and possess waste.
? Information Need 2.4.5:  Determination that the waste can be transported to the surface 
and delivered to waste-handling surface facilities for normal and abnormal conditions 
(DOE 1988, Section 8.3.5.2.5).  This need, which addresses the transport of waste 
packages from their emplacement locations to surface facilities, still exists.  The need 
will be considered in the preliminary MGR design after its design requirements for 
retrievability have been formulated.  The Retrievability Strategy Report (CRWMS 
M&O 1998h, Section 7) has several specific scenarios for returning retrieved waste to 
the surface.  Additionally, the report requires that the MGR design shall include the size 
and location of temporary storage facilities for retrieved waste packages and shall have 
the capability to store all the emplaced waste.  The facility does not need to be designed 
or constructed in parallel with the repository design, but the size and preliminary 
location of the facility within the general repository operations area must be documented 
prior to license application.  Before receiving the license to receive and possess waste, 
this site shall be characterized based on established criteria for suitability, or by analysis 
providing confidence that the site is suitable for temporary storage.
? Proof that the waste can be transported to the surface (proof-of-principle and 
prototype tests showing that retrieval will be possible) will be provided by the tests for 
assurance that waste packages can be accessed and moved under normal and abnormal 
conditions during the operational period.
? Information Need 2.4.6:  Determination that the retrieval requirements set forth in 
10 CFR 60.111(b) (10 CFR 63.111(e)) are met using reasonably available technology 
(DOE 1988, Section 8.3.5.2.6).  This generic requirement remains and was considered in 
the Retrievability Strategy Report (CRWMS M&O 1998h) and in the preliminary MGR 
design.  The Retrievability Strategy Report also acknowledges this requirement in 
Table 3-1, which is a listing of past studies and their applicability to the present design.  
The table lists four other studies or reports that establish the requirement and indicates 
that the requirement is still applicable.
Changes and Status.  Preliminary retrieval concepts are described in the Mined Geologic 
Disposal System Advanced Conceptual Design Report (CRWMS M&O 1996g, Volume II, 
Section 9.2).  The potential retrieval is expected to be significantly different from the SCP 
(DOE 1988) conceptual design of the repository and waste package.
The general five-step approach defined in the SCP (DOE 1988) for resolving Issue 2.4, however, 
is not expected to change.  The five steps are as follows:
1. Evaluate regulations and dataevaluate regulatory requirements and existing site data, 
designs and analyses to determine the functions and processes that must be performed 
to not preclude retrieval.
2. Allocate performanceestablish performance measures and goals (design criteria) for 
the processes that contribute to performing those functions.
3. Identify retrieval conditionsidentify normal and credible abnormal conditions for 
retrieval-related operations and identify input items needed from Issue 4.4.  (Are the 
technologies of repository construction, operation, closure, and decommissioning 
adequately established to support resolution of performance issues?  See discussion of 
SCP Section 8.3.2.5 (DOE 1988) in Section 2.2 of this document.)
4. Identify input itemsidentify and request site parameters necessary to meet the goals of 
related issues for common system elements or develop the reference preclosure 
repository design, operations plan, supporting analyses and demonstrations requested to 
support resolution of all related issues.
5. Conduct compliance analysisconduct a compliance analysis to critically evaluate 
whether the appropriate retrieval conditions have been considered, whether the input 
items provided by Issue 4.4 are complete and sufficient, and whether the performance 
goals are met.
The Retrievability Strategy Report (CRWMS M&O 1998h) was completed in FY 1997, 
including the formulation of related MGR design requirements.  Using the MGR advanced 
conceptual design, this study identified seven scenarios that may require retrieval, identified 
retrieval options, and recommended design features to facilitate retrieval and the method of 
retrieving the emplaced waste to a surface storage facility.
5.3	HIGHER LEVEL FINDINGS AND NRC SITING CRITERIA (SCP 
SECTIONS 8.3.5.6, 8.3.5.7, 8.3.5.17, AND 8.3.5.18)
The three higher level findings sections (DOE 1988, Sections 8.3.5.6, 8.3.5.7, and 8.3.5.18) and 
the NRC siting criteria section of the SCP (SCP Section 8.3.5.17) are discussed together because 
of their interdependence and because proposed revisions of 10 CFR 960 would affect all of them 
in a related manner.
Higher level findings and NRC siting criteria refer to criteria in DOE and NRC regulations for 
assessing the acceptability of specific aspects of a candidate repository site and the acceptability 
of the overall performance of a repository that would be constructed at the site.  The NRC siting 
criteria are specified in 10 CFR 60.122.  These criteria are defined in terms of favorable 
conditions and potentially adverse conditions that must be investigated and analyzed.  Higher 
level findings are findings with respect to qualifying conditions and disqualifying conditions that 
are specified by the DOEs siting guidelines in 10 CFR 960.  These findings must be made 
before the DOE can recommend a site for development as a repository.  The qualifying and 
disqualifying conditions are defined in terms of preclosure and postclosure system guidelines 
and technical guidelines.  The system guidelines specify requirements for the overall 
performance and characteristics of a geologic repository, and the technical guidelines identify 
requirements for specific attributes of the site that contribute to the overall performance and 
characteristics.  The technical guidelines incorporate favorable conditions and potentially 
adverse conditions that correspond closely to the NRCs siting criteria in 10 CFR 60.  The 
qualifying conditions must be satisfied for a site to be acceptable and a site is unacceptable if any 
of the disqualifying conditions apply (see footnote 1, page I-1).
Since the SCP (DOE 1988) was published in 1988, the regulatory framework for site selection 
has changed significantly.  In particular, the NWPA, as amended in 1987, directed the DOE to

cease characterization of two other candidate sites and to characterize the Yucca Mountain site 
only.  This legislation rendered moot requirements in 10 CFR 960 for comparative site 
evaluations.  In addition, the Energy Policy Act of 1992 directed the EPA to develop site-specific 
standards for the performance of a repository at Yucca Mountain and directed the NRC to 
conform its implementing standards in 10 CFR 60 with the EPAs new performance standards.  
The NRC published Proposed Rulemaking on February 22, 1999 (64 FR 8640) to issue site-
specific requirements in 10 CFR 63 for disposal of high-level radioactive wastes in a potential 
repository at Yucca Mountain, Nevada.  The proposed rule would render the criteria of 
10 CFR 60 not applicable to a repository at Yucca Mountain.  The proposed 10 CFR 63 
risk-informed, performance-based licensing regulation does not include specification of design 
and siting criteria.  The technical criteria in the proposed rule specify overall performance 
objectives for preclosure and postclosure phases and will be amended, if necessary, when the 
EPA issues final standards for Yucca Mountain.  The EPA published Proposed Rulemaking on 
August 27, 1999 (64 FR 46976) to issue environmental radiation protection standards for Yucca 
Mountain, Nevada, in 40 CFR 197 (see footnote 1, page I-1).  The EPA final rule 40 CFR 197, 
Public Health and Environmental Radiation Protection Standards for Yucca Mountain, 
Nevada, became effective on July 13, 2001.
In response to the legislative changes and in consideration of the knowledge gained about the 
Yucca Mountain site, the DOE prepared a draft Notice of Proposed Rulemaking to amend the 
general guidelines for site recommendation in 10 CFR 960.  The amended rule would retain the 
existing guidelines for potential future use at other sites and would, in a new subpart, clarify and 
focus the guidelines to be used in evaluating the suitability of the Yucca Mountain site.  Two 
system guidelines would be applied to Yucca Mountain:  (1) a postclosure system guideline that 
addresses waste containment and isolation and (2) a preclosure system guideline that addresses 
radiological safety.  Each system guideline would have an associated qualifying condition.  The 
DOE published the Notice of Proposed Rulemaking on December 16, 1996 (61 FR 66158), to 
amend 10 CFR 960 by adding a new site-specific subpart for Yucca Mountain.  The public 
comment period closed May 16, 1997.  The DOE has proposed revising its December 16, 1996, 
proposal to respond to comments received during the comment period, provide descriptions of 
and references to the Viability Assessment of a Repository at Yucca Mountain (DOE 1998a), and 
make conforming changes in response to proposed 10 CFR 63 (64 FR 8640) (see footnote 1, 
page I-1).
The work described in the SCP (DOE 1988) is organized around the resolution of a number of 
technical issues, including the making of higher level findings and the demonstrations required 
by the NRC siting criteria.  The SCP does not define specific information needs and 
performance assessment activities for this purpose.  Any changes from the SCP and the status 
of the work related to these issues is summarized next.
5.3.1	Higher-Level Findings for Preclosure Radiological Safety (SCP Section 8.3.5.6)
Background and SCP Plans.  This section addresses Issue 2.5, which asks whether the 
higher-level findings required by 10 CFR 960 can be made for the qualifying condition of the 
preclosure radiological safety system guideline and the qualifying and disqualifying conditions 
of the technical guidelines for population density and distribution, site ownership and control, 
meteorology, and offsite installations and operations.  Resolution of this issue would require 
presenting sufficient evidence to support either a positive or negative higher-level finding for 
each qualifying and disqualifying condition associated with preclosure radiological safety. 
Changes and Status.  The DOEs proposed amendment to 10 CFR 960 would retain, for the 
Yucca Mountain site, a preclosure radiological system guideline and its associated qualifying 
condition and would eliminate evaluation of specific technical guidelines.  However, the 
information required to assess compliance with the technical guidelines would have to be 
collected and analyzed to assess compliance with the system guideline.  The Preliminary 
Preclosure Safety Assessment for Monitored Geologic Repository Site Recommendation (BSC 
2001g) documents the preliminary safety assessment of MGR operations in the preclosure period 
including the identification of facility hazards and their potential for initiating events, 
identification of MGR design basis events, evaluation of design basis event occurrence 
frequencies and consequences, and identification of those structures, systems, and components 
important to safety.
5.3.2	Higher Level Findings for Ease and Cost of Construction (SCP Section 8.3.5.7)
Background and SCP Plans.  This section addresses Issue 4.1, which asks whether higher level 
findings required by 10 CFR 960 can be made for the preclosure system guideline for ease and 
cost of siting, construction, operation, and closure and for the qualifying and disqualifying 
conditions of the technical guidelines for surface characteristics, rock characteristics, hydrology, 
and tectonics.  The guidelines of this section address whether construction of a repository is 
technically feasible, based on reasonably available technology, and whether repository costs 
would be reasonable in comparison with other siting options.  Resolution of this issue would 
require presenting sufficient evidence to support either a positive or negative higher-level finding 
for each qualifying and disqualifying condition associated with the preclosure guideline on ease 
and cost of repository construction, operation, and closure.
Changes and Status.  Under the proposed amendments to 10 CFR 960, no findings would be 
required for these guidelines for the Yucca Mountain site.  Technical feasibility would be 
addressed implicitly in the design process.  The comparative cost criterion was rendered moot by 
the NWPA, as amended.
5.3.3	Higher Level Findings for Postclosure System and Technical Guidelines 
(SCP Section 8.3.5.18)
Background and SCP Plans.  This section addresses Issue 1.9, which asks whether higher level 
findings can be made for the postclosure system guideline for waste containment and isolation 
and the qualifying and disqualifying conditions of the technical guidelines for geohydrology, 
geochemistry, rock characteristics, climatic changes, erosion, dissolution, tectonics, and human 
interference.  Resolution of this issue would entail presenting sufficient evidence to support 
either a positive or negative higher-level finding for each qualifying and disqualifying condition 
associated with postclosure repository performance.
Changes and Status.  The proposed amendments to the siting guidelines would, for the Yucca 
Mountain site, retain a postclosure system guideline for waste containment and isolation and an 
associated qualifying condition and would eliminate evaluation of specific technical guidelines.  
However, the information addressed in the technical guidelines will be integrated into the TSPAs 
that the DOE will conduct to evaluate compliance with the postclosure system guideline.
5.3.4	NRC Siting Criteria (SCP Section 8.3.5.17)
Background and SCP Plans.  This section addresses Issue 1.8, which asks whether 
demonstrations for favorable and potentially adverse conditions can be made as required by 
10 CFR 60.122.  The SCP (DOE 1988) defines detailed steps for two separate strategies for 
resolving this issue with respect to demonstrations required for favorable and potentially adverse 
conditions.  Both are strongly tied with resolving Issue 1.1, which addresses the NRCs overall 
system postclosure performance objective (10 CFR 60.112).
Changes and Status.  These demonstrations will be included in the license application.  
Specifics may be different because of potential changes in the postclosure performance 
objectives resulting from the issuance of new EPA regulations at 40 CFR 197 (66 FR 32074) and 
new NRC regulations at 10 CFR 63 (66 FR 55732) (see footnote 1, page I-1).
5.4	POSTCLOSURE PERFORMANCE ASSESSMENT AND PRE-WASTE-
EMPLACEMENT GROUNDWATER TRAVEL TIME (SCP SECTIONS 8.3.5.8, 
8.3.5.12, 8.3.5.13, 8.3.5.14, AND 8.3.5.15)
The principal postclosure performance assessment sections and the pre-waste emplacement 
groundwater travel time section of the SCP (DOE 1988, Sections 8.3.5.8, 8.3.5.12, 8.3.5.13, 
8.3.5.14, and 8.3.5.15) are covered together because of their interdependence and because the 
revised TSPA approach addresses them in an integrated manner.
Since the issuance of the SCP (DOE 1988), two major changes have occurred.  The first change 
had been driven by the expected changes in regulatory performance measures and the second by 
a change in analysis philosophy.
The primary change in the expected regulatory criteria is from a radionuclide release-based 
standard to a radiation dose-based standard.  In this instance, the final representation changes 
from a complementary cumulative distribution function of radionuclide release to some measure 
of radiation dose to an individual or population.  From a performance assessment standpoint, this 
also changes the relative importance of certain components of the total system (such as the 
increased importance of the details of the saturated zone).  From an analysis standpoint, the 
primary change would be the need for analysis tools for the prediction of radiation doses from all 
potential pathways and the analysis of biosphere radionuclide transport and radiation exposures 
to humans.
The overall postclosure performance assessment approach uses a series of detailed mathematical 
models and computer codes that are abstracted into an integrated model to assess the various 
subsystem and total system requirements.  The interdependence of the various processes 
important to performance requires that each of the subsystem requirements be assessed in the 
context of the total system.  The total system performance tool to be used in the site 
recommendation reflects the current understanding of the site and design using alternative 
conceptual models and parameter distributions that reflect both their variability and uncertainty.  
A set of model abstraction and testing activities was used to develop the mathematical 
representation for each important process within the total system.  These activities (listed below) 
were synthesized into the total system analysis tool.
The appropriate analyses will be run as part of the TSPA to preserve the integrity of the process 
interdependencies.  The results for each subsystem will be abstracted from the appropriate point 
within the total system analyses.  For the groundwater travel time, work on fast-path flow has 
been explicitly incorporated in the development of the unsaturated and saturated zone fluid flow 
and radionuclide transport elements (Ho et al. 1996).  Both pre-waste emplacement groundwater 
travel time and post-waste emplacement groundwater travel time have been assessed and 
reported previously (Arnold et al. 1995; Altman et al. 1996).  These specific analyses can be 
updated together with other work on relevant processes in the context of the total system analysis 
development.
The postclosure performance assessment approach just described was developed between 1991 
and 2001 through iterative TSPAs.  The first TSPA was performed in 1991 (Barnard et al. 1992; 
Eslinger et al. 1993).  Subsequent TSPAs were performed in 1993 (CRWMS M&O 1994a; 
Wilson et al. 1994) and 1995 (CRWMS M&O 1995f).  In 1996, testing of model abstractions 
(CRWMS M&O 1996l) and scenario development (Barr et al. 1996) further enhanced the TSPA 
methodology, and led to the TSPA methodologies used in the TSPA-VA (DOE 1998a, 
Volume 3), TSPA-SR (CRWMS M&O 2000af), and the SSPA Vol. 2 (BSC 2001h).  The major 
activities include:
? Unsaturated zone flow testing and abstraction
? Unsaturated zone transport testing and abstraction
? Saturated zone flow and transport testing and abstraction
? Thermohydrologic flow testing and abstraction
? Waste package degradation testing and abstraction
? Waste form degradation testing and abstraction
? Waste form mobilization testing and abstraction
? Near-field environment testing and abstraction
? Biosphere testing and abstraction
? Disturbed processes testing and abstraction
? TSPA tools and methodology.
Following are summaries of the current applicability of each postclosure performance 
assessment and the pre-waste emplacement groundwater travel time SCP (DOE 1988) section 
and related information needs.
5.4.1	Strategy for Postclosure Performance Assessment (SCP Section 8.3.5.8)
Background and SCP Plans.  This section addresses the development of the postclosure 
performance assessment strategy for resolving Key Issue 1.  This issue asks whether the MGR at 
Yucca Mountain would isolate the radioactive waste from the accessible environment after 
closure in accordance with the requirements of 10 CFR 60, 10 CFR 960, and 40 CFR 191.  The 
SCP (DOE 1988) does not define specific information needs and performance assessment 
activities for the development of the postclosure performance assessment strategy.
The detailed plans for assessing postclosure performance are described in SCP, Sections 8.3.5.9 
through 8.3.5.18 (DOE 1988), which address the resolution of Issues 1.1 through 1.9.  These 
issues are based on the postclosure performance requirements of 10 CFR 60, 10 CFR 960, and 
40 CFR 191 (see footnote 1, page I-1).  The overall strategy defined in the SCP includes the 
interrelationships of these issues for resolving the Key Issue 1 and sequential steps for 
conducting iterative assessments.  Iterative assessments are planned to provide feedback to the 
site program, to MGR design, and to affect conceptual and mathematical model improvements.  
These steps are (paraphrased from the SCP):
1. Compile site and design data for the analyses and define their uncertainties.
2. Define conceptual models and scenarios and boundaries for the calculations.
3. Evaluate the adequacy of the data for the next step and define additional data needs if 
the data are not adequate.
4. Test and validate conceptual and mathematical models, including computer codes.
5. Reevaluate the adequacy of the data for the next step and define additional data needs if 
the data are not adequate.
6. Calculate performance measures, including uncertainties, and compare with regulatory 
criteria.
7. Reevaluate the adequacy of the data for the next step and define additional data needs if 
the data are not adequate.
8. Propose resolution of the issue.
Although the questions in the SCP (DOE 1988) on the adequacy of the data do not specify the 
following, the adequacy of the MGR design, the scenario formulations, the conceptual models, 
the mathematical models, and the computer codes, is implicit in these questions.  Consequently, 
improvements or changes in the MGR design and in the conceptual/mathematical models and 
computer codes may also be necessary in this stepwise process.  The whole process is repeated 
iteratively during the site characterization phase until sufficient confidence in meeting the 
regulatory criteria is achieved to submit a license application to the NRC.
Changes and Status.  Postclosure performance assessment activities have been revised in 
anticipation of possible new EPA standards for a potential repository at Yucca Mountain.  The 
strategy was defined in the Total System Performance AssessmentViability Assessment Plan 
(CRWMS M&O 1996k), which was based on the waste strategy to protect public health and 
safety after closure of a repository at Yucca Mountain (Younker 1996b), TSPAs conducted to 
date (Barnard et al. 1992; Eslinger et al. 1993; CRWMS M&O 1994a; Wilson et al. 1994; 
CRWMS M&O 1995f; DOE 1998a), the Description of Performance Allocation (CRWMS 
M&O 1996o), and numerous other Project reports.  The next major performance assessment was 
conducted in support of the site recommendation.  The Total System Performance Assessment-
Site Recommendation Methods and Assumptions (CRWMS M&O 2000q) presents the overall 
goals, objectives, scope, methods, approach, and assumptions used in development of the Total 
System Performance Assessment for the Site Recommendation (TSPA-SR) (CRWMS M&O 
2000af).  In addition, supplemental TSPA analyses were performed to update science and 
models, quantify uncertainties, and evaluate lower temperature operating mode.  The results of 
these analyses are documented in SSPA Vol. 2 (BSC 2001h).
5.4.2	Groundwater Travel Time (SCP Section 8.3.5.12)
Background and SCP Plans.  This section addresses Issue 1.6, which asks whether the site will 
meet the performance objective for pre-waste-emplacement groundwater travel time as required 
by 10 CFR 60.113.  The SCP approach to resolving Issue 1.6 is addressed by five information 
needs.  The planned resolution of Issue 1.6 centered around the development of groundwater 
flow models for the unsaturated and saturated zones and the calculation of the groundwater travel 
time with these models (see footnote 1, page I-1).
Changes and Status.  A comprehensive analysis of pre-waste-emplacement groundwater travel 
time has been completed (Altman et al. 1996) and no new analyses are planned because of 
expected changes in the NRC regulations.  Post-waste-emplacement groundwater transport time 
analyses will continue as needed to evaluate thermal-hydrological regime in support of 
postclosure performance assessments of the overall repository system.  The saturated zone 
component of the TSPA-SR model examines the groundwater transport and radionuclide 
transport times (CRWMS M&O 2000af).
5.4.3	Total System Performance (SCP Section 8.3.5.13)
Background and SCP Plans.  This section addresses Issue 1.1, which asks whether the MGR 
would meet the system performance objective for limiting radionuclide releases to the accessible 
environment as required by 10 CFR 60.112 and 40 CFR 191.13.  This issue would be resolved 
by identifying potentially disruptive scenarios, developing models of these scenarios and the 
affected natural and engineered barrier system processes, and then modeling these scenarios and 
processes in order to develop the cumulative complementary distribution function required by 
40 CFR 191.13 (see footnote 1, page I-1).
Changes and Status.  Analyses, including potentially disruptive scenarios, have been included 
in past iterations of postclosure performance assessments of the overall repository system.  
Although analyses of radionuclide transport to the accessible environment will continue if a 
radiological risk-based standard is adopted, the integration of radionuclide release over the 
boundary of the accessible environment for 10,000 years and the calculation of an empirical 
complementary cumulative distribution function would no longer be needed.
5.4.4	Individual Protection (SCP Section 8.3.5.14)
Background and SCP Plans.  This section addresses Issue 1.2, which asks whether the MGR 
would meet the requirements for limiting individual radiation doses in the accessible 
environment for 1,000 years after waste disposal as required by 40 CFR 191.15.  This issue 
would be resolved through the calculation of radioactive releases from the waste packages in the 
first 1,000 years following repository closure, of the transport of aqueous radionuclides through 
the unsaturated and saturated zone to the boundary of the accessible environment, of the 
transport of carbon-14 to the ground surface, and of radiation doses to the maximally exposed 
individual through drinking of the contaminated water and inhaling the contaminated air.  The 
issue would be resolved if the calculated doses would be below the limits set by 40 CFR 191.15.
Changes and Status.  The analyses of radiation doses from drinking contaminated water and 
from carbon-14 releases will become a component of the calculation of postclosure radiological 
risk from all environmental pathways if a radiological risk standard is adopted.  The most recent 
calculations of radiation doses from drinking water and carbon-14 were included in the TSPA-
VA (DOE 1998a, Volume 3, Section 3.8.3), the TSPA-SR (CRWMS M&O 2000af), and the 
SSPA Vol. 2 (BSC 2001h).
5.4.5	Groundwater Protection (SCP Section 8.3.5.15)
Background and SCP Plans.  This section addresses Issue 1.3, which asks whether the MGR 
would meet the requirements for the protection of special sources of groundwater for 1,000 years 
after waste disposal as required by 40 CFR 191.16.  This issue would be resolved through the 
same calculations as above with respect to calculating radioactive releases from the engineered 
barrier system and aqueous radionuclide transport to the accessible environment, and then 
comparing the radionuclide concentrations in the groundwater with the limits set by 
40 CFR 191.16.
Changes and Status.  The analyses of radionuclide concentrations in the groundwater of the 
saturated zone in the accessible environment will become a component of the calculation of 
postclosure radiological risk from all environmental pathways if a radiological risk standard is 
adopted.  The most recent calculations of radionuclide concentrations in the groundwater of the 
saturated zone in the accessible environment were included in the TSPA-VA (DOE 1998a, 
Volume 3, Section 3.7.3), TSPA-SR (CRWMS M&O 2000af), and the SSPA Vol. 2 (BSC 
2001h).
5.5	CONTAINMENT BY WASTE PACKAGE/WASTE PACKAGE MATERIALS 
TESTING AND MODEL DEVELOPMENT (SCP SECTION 8.3.5.9)
The SCP (DOE 1988) lists activities that address Issue 1.4, which asks whether the waste 
package would meet the performance objective for containment as required by 10 CFR 60.113.  
The SCP objective for Issue 1.4 was to provide total containment of the enclosed waste for the 
containment period under anticipated repository conditions recognizing technological limitations 
and residual uncertainties.  The SCP notes that the performance of the waste package during 
the containment period would be best achieved by minimizing the residual uncertainties.  The 
residual uncertainties in predicting performance are caused by several factors:  the inherent 
limitations associated with manufacturing, handling, and emplacement operations; the 
uncertainty in developing a complete understanding of the behavior of waste package materials; 
and the uncertainty in predicting the future environment of each waste package. Accordingly, 
this issue is closely coupled with Issue 4.3 (Are the waste package production technologies 
adequately established for the resolution of the performance issues?) and Issue 1.10 (Have the 
characteristics and configurations of the waste packages been adequately established to show 
compliance with the postclosure design criteria of 10 CFR 60.135, and provide information for 
the resolution of performance issues?).  Issues 4.3 and 1.10 are discussed for SCP 
Sections 8.3.4.4 and 8.3.4.2, respectively, in Section 4 of this document (see footnote 1, page 
I-1).
Background and SCP Plans.  The SCP (DOE 1988) describes the approach to resolving 
Issue 1.4 within the logic of five information needs:  (1) waste package design features that 
affect the performance of the container, (2) material properties of the container, (3) scenarios and 
models needed to predict the rate of degradation of the container material, (4) estimates of the 
rates and mechanisms of container degradation in the repository environment for anticipated and 
unanticipated processes and events, and calculation of the failure rate of the container as a 
function of time, and (5) determination of whether the set of waste packages meets the 
performance objective for substantially complete containment for anticipated processes and 
events.
Changes and Status.  Although the waste package design concept has been modified, 
considerable linkage still exists between the SCP (DOE 1988) and the current metal barriers 
selection and test program.  SCP Issue 1.4 and its information needs remain fundamentally 
unchanged.  The current waste package container designs include families of materials other than 
the copper-base materials and the iron to nickel-base austenitic materials that were the subject 
of the SCP Conceptual Design.  The testing and modeling program has been expanded to 
encompass corrosion allowance, corrosion resistant, and intermediate materials; and the test 
environments have been expanded to bracket the range of temperatures and environments that 
may be encountered for the different waste package and repository design options.
The SCP (DOE 1988) mentions that alternative designs, including multiple metallic barriers, 
might be considered, but it does not discuss which materials and how they might be configured.  
Many of the same individual corrosion degradation modes discussed in the SCP also apply to 
multiple-barrier containers.  Defense-in-depth, which helps mitigate common mode failures in 
the multiple barriers, is a major element of the current program.  In the current design, the 
titanium drip shield constitutes an added barrier with a different degradation mode.  Accordingly, 
the testing and modeling work has been moved from single-metal system activities to 
multiple-barrier system activities.
The performance modeling activities for the calculation of waste package containment times and 
the determination of whether the set of waste packages meets the performance objective remain 
consistent with the approach described in SCP Sections 8.3.5.9.4 and 8.3.5.9.5.  The following 
sections have been moved to the design sections:  SCP Section 8.3.5.9.1.1, Integrate Design and 
Materials Information (Metal Container), Subactivities 1.4.1.1.4 and 1.4.1.1.5, dealing with state 
of stress and weld integrity, and SCP Section 8.3.5.9.1.2, Integrate Design and Materials 
Information (Alternate Barriers Investigations), Subactivity 1.4.1.2.5, dealing with 
nondestructive characterization.
Changes to the metal barrier selection and testing program result primarily from major changes 
in the technical scope of the waste package activities that have occurred in the advanced 
conceptual design phase of the Project.  In particular, the shift from the SCP conceptual design 
single-barrier container to the advanced conceptual design multiple-barrier concept has resulted 
in a more robust waste package, as well as additional engineered barriers such as the drip 
shield, that might better be demonstrated to meet the containment objectives.
The SCP conceptual waste package design is described in the Site Characterization Plan 
Conceptual Design Report (SNL 1987).  The multiple-barrier approach for waste package 
container design is discussed in the Controlled Design Assumptions Document (CRWMS 
M&O 1998c, p. 3-69) and the bimetallic option currently being pursued is described in the 
Mined Geologic Disposal System Advanced Conceptual Design Report (CRWMS M&O 1996g, 
Volume III, Section 6.1).  The Metal Barrier Selection and Testing scientific investigation plan 
(McCright 1996) documents the changes to the SCP, in response to the advanced conceptual 
design multibarrier approach to waste package containers.  Results from the activities completed 
to date in this investigation are documented in the Engineered Materials Characterization 
Report:  Volume 3 Revision 1.1.  Corrosion Data and Modeling Update for Viability Assessment 
(McCright 1998).  Documentation of test results and model projections are made in PMRs.
5.6	ENGINEERED BARRIER RELEASE RATES/WASTE FORM TESTING AND 
MODEL DEVELOPMENT (SCP SECTION 8.3.5.10)
Background and SCP Plans.  The SCP (DOE 1988) approach consists of activities that address 
Issue 1.5, which asks whether the waste package and the engineered barrier system would meet 
the performance objective for radionuclide release rates as required by 10 CFR 60.113.  The 
activities include waste form characterization, alteration, dissolution, and radionuclide release, as 
well as model development and utilization to determine compliance (see footnote 1, page I-1).
Changes and Status.  The current approach is essentially the same as that given in the SCP.  
The current effort is detailed in the Waste Form Degradation Process Model Report (CRWMS 
M&O 2000r) for the waste form testing and modeling.  Related performance assessment 
activities are given in companion documents.  Most of the changes deal with deferring activities 
because of reduced need for the activity indicated by information collected to date.  The 
following discusses the five information needs and the changes, if any, between the SCP 
(DOE 1988) and the current approach.
? Information Need 1.5.1:  Waste package design features that affect radionuclide release 
(SCP Section 8.3.5.10.1).  The activity for this information need deals with integration 
of waste form data.  The activity is essentially the same as planned in the SCP except 
that the vehicle for information transfer has become the Monitored Geologic Repository 
Project Description Document (Curry 2001) and relevant AMRs, rather than the Spent 
Fuel Working Group described in the SCP.  The Spent Fuel Working Group is no longer 
active.
? Information Need 1.5.2:  Material properties of the waste form (SCP Section 8.3.5.10.2).  
The two activities for this information are (1) characterization of the spent nuclear fuel 
waste form and (2) characterization of the high-level waste glass forms.  These activities 
address dissolution and oxidation of spent nuclear fuel, Zircaloy, hardware and 
carbon-14 release, and leaching of high-level waste glass.  The current program has 
focused on testing spent nuclear fuel and high-level waste glass.  The testing of 
hardware and carbon-14 has been deferred.  Spent fuel and glass data and models have 
been developed to determine waste form degradation rates for different design options 
and to support performance assessment.  Bounding models have also been developed for 
the large spectrum of DOE spent nuclear fuel.
? Information Need 1.5.3:  Scenarios and models needed to predict the rate of radionuclide 
release from the waste package and engineered barrier system (SCP Section 8.3.5.10.3).  
The five activities for this information need are (1) the integration of scenarios for 
radionuclide releases from the waste packages, (2) the development of a geochemical 
speciation and reaction model, (3) the development of models for radionuclide release 
from the spent nuclear fuel, (4) the development of models for radionuclide release from 
the high-level waste glass forms, and (5) the development of waste package performance 
assessment models.  Scenarios for waste package criticality have been developed as part 
of the waste package development efforts.  Also included is the use of the 
thermodynamic database GEMBOCHS and the geochemical computer code EQ3/6 
(Daveler and Wolery 1992; Wolery 1992a and 1992b; Wolery and Daveler 1992).  
The GEMBOCHS work has concentrated on augmenting the database with data from 
worldwide sources as they become available.  Recent EQ3/6 modeling work has been 
limited and focused on simulating geochemical speciation and the behavior of spent 
nuclear fuel and high-level waste glass, as well as the determination of in-package 
geochemical environment.  The GEMBOCHS and EQ3/6 activities closely follow the 
plan in the SCP (DOE 1988).  Detailed mathematical models have been developed for 
waste form dissolution and radionuclide release from spent nuclear fuel and high-level 
waste glass on the basis of the experimental results.  These detailed models are 
synthesized in the reactive transport code GOLDSIM (V6.04.007 STN:  100344-
6.04.007-00) and the waste package degradation computer code WAPDEG (Atkins and 
Lee 1996; Lee et al. 1996a and 1996b).  The code also includes a model for the release 
of colloidal material as described in the Waste Form Degradation Process Model Report 
(CRWMS M&O 2000r).
? Information Need 1.5.4Determination of the release rates of radionuclides from the 
waste package and engineered barrier system for anticipated and unanticipated events 
and processes (SCP Section 8.3.5.10.4).  The two activities for this information are 
(1) deterministic and (2) probabilistic calculations of radionuclide releases from the 
waste packages.  The current work closely follows the plan in the SCP.  Recent analyses 
of releases have been part of TSPAs (Barnard et al. 1992; Eslinger et al. 1993; CRWMS 
M&O 1994a; Wilson et al. 1994; CRWMS M&O 1995f; DOE 1998a, Volume 3; 
CRWMS M&O 2000r).
? Information Need 1.5.5Determination of the amount of radionuclides leaving the 
near-field environment of the waste package (DOE 1988, Section 8.3.5.10.5).  The two 
activities for this information need are (1) the determination of radionuclide transport 
parameters and (2) radionuclide transport modeling in the near-field environment.  The 
available information has been evaluated and collected in the Engineered Barrier System 
Degradation, Flow, and Transport Process Model Report (CRWMS M&O 2000t), 
which feeds the Near Field Environment Process Model Report (CRWMS M&O 
2000u).  Detailed process models are based on experimental results, but have not been 
validated.  Model applications include sensitivity studies, support of engineered barrier 
system studies, and components of TSPAs.
5.7	SEAL PERFORMANCE (SCP SECTION 8.3.5.11)
Background and SCP Plans.  SCP Section 8.3.5.11 (DOE 1988) addresses whether the design 
of the seal system will meet the requirements of 10 CFR 60.134(a) and (b) and how seal 
performance will contribute to the engineered barrier system performance in accordance with 
10 CFR 60.113(a)(1).  The seal system is defined as being composed of shafts, ramps, 
exploratory boreholes and their seals, and the sealing components of the underground facility 
(see footnote 1, page I-1).
Changes and Status.  The overall goals of sealing have not changed, which are to minimize 
water flow to the waste packages through man-made openings in the host rock, minimize 
gaseous radionuclide releases to the ground surface through these openings, and minimize 
aqueous radionuclide transport from the waste packages to the saturated zone through these 
openings.  Preliminary analyses of seal performance, seal test planning, and evaluations of 
sealing components have been completed (Fernandez and Freshley 1984; Fernandez 1985; 
Fernandez, Kelsall et al. 1987; Licastro et al. 1990; Fernandez, Case et al. 1993; Van Sambeek 
et al. 1993; Fernandez, Case et al. 1994; Fernandez and Richardson 1994).  Because of 
uncertainties in new regulations for postclosure MGR performance, the goals and performance 
measures listed in the SCP (DOE 1988), however, may no longer be relevant.  Consequently, the 
seal performance goals, the possibility to seal selectively with respect to needed seal 
performance and locations, and the need to seal at all from a postclosure waste isolation 
performance standpoint were revisited.
A systems study was done that identified how components of the sealing systems will meet the 
expected regulations and what additional work will need to be performed before licensing.  The 
results of the study showed that sealing of shafts, ramps, and boreholes will be necessary.  
The study further determined the requirements that were needed for such a seal system.  The 
system recommended was twofold:  actual sealing of the shafts, ramps, and boreholes in 
combination with an underground water storage capability that would accommodate some 
moisture and allow it to drain without contacting the waste packages.  The permeabilities that the 
study recommends for the seals to limit potential water flow through the shafts ramps and 
borehole seals were found to be readily achievable using existing materials (Fernandez and 
Richardson 1994, Section 6.0).
Some preliminary design work has been done on seals (see Section 3 of this document), but a 
substantial portion of the sealing design information was not intended to be developed until after 
the start of waste emplacement.  Sealing of boreholes is possibly the exception because some 
boreholes may be sealed before the repository becomes operational.
Additional detail is provided in the repository section of this document that addresses SCP 
Investigation 8.3.3.2.2 (materials and characteristics of seals for shafts, drifts and boreholes).
5.8	PERFORMANCE CONFIRMATION (SCP SECTION 8.3.5.16)
SCP Section 8.3.5.16 (DOE 1988) addresses Issue 1.7 on performance confirmation, which is 
directly related to the performance confirmation program requirements of 10 CFR 60.137 and 
Subpart F (consisting of 60.140 through 60.143) (see footnote 1, page I-1).
Background and SCP Plans.  The SCP (DOE 1988) described preliminary plans for a 
performance confirmation program that would encompass two major phases:  (1) the baseline 
phase and (2) the confirmation phase.  The submittal of the license application marks the division 
between the two phases.
The baseline phase would consist of acquiring and developing information during site 
characterization.  This phase would include developing information on subsurface conditions and 
natural systems important to the performance assessment to be provided in the license 
application and those aspects of design integral to the assessment and monitoring and analyzing 
changes in this baseline information as a result of site characterization and predicting changes 
resulting from construction and operation.
The confirmation phase would consist of in situ monitoring, laboratory and field testing, and 
associated analyses required to confirm assumptions regarding the actual subsurface conditions 
at the site and the functioning of the engineered and natural systems and components as 
predicted by the performance assessment calculations presented in the license application.
A subset of the testing conducted during site characterization would provide the baseline data 
needed for performance confirmation.  In Tables 8.3.5.16-1 and 8.3.5.16-2 (DOE 1988), the SCP 
listed specific monitoring and testing activities planned during site characterization and testing 
activities planned to be continued for performance confirmation.  These activities were not 
intended to be complete but rather to indicate the monitoring and testing tentatively identified at 
that time as being useful for performance confirmation.
Changes and Status.  The Performance Confirmation Plan CRWMS M&O 2000v) and the 
Monitored Geologic Repository Test & Evaluation Plan CRWMS M&O 2000y) are being 
updated.  This work will evaluate possible changes in the testing program due to revision of 
YMP requirements, the evolution of the design concept, and the finalization of 10 CFR 63 and 
40 CFR 197.
The present Performance Confirmation Plan (CRWMS M&O 2000v) has revised the SCP 
approach from two distinct program phases to a more flexible approach, which initiates baseline 
development followed by testing at a time applicable to the individual activity, allowing for 
differing activity starting times and schedules.  The plan selects testing and monitoring activities 
based on the identification of key performance confirmation processes or factors.  Key 
performance confirmation factors for the program were identified based on (1) factors that are 
important to repository safety based on the total system performance assessments and in 
accordance with the repository safety strategy; (2) other factors potentially important to 
postclosure safety, such as additional data needs identified through the development of process 
models used to predict the repository performance; (3) factors or testing indicated by current 
regulatory guidance and repository requirements; and (4) factors due to licensing conditions.
Concepts and potential testing and monitoring activities for performance confirmation are 
described in Performance Confirmation Plan (CRWMS M&O 2000v).  The plan is identified as 
part of a more-comprehensive Monitored Geologic Repository Test & Evaluation Plan 
(CRWMS M&O 2000y) with testing conducted to address multiple concerns.  As presently 
defined, the performance confirmation program includes simulation testing of the postclosure 
environment and process monitoring of conditions in and around the emplacement drifts together 
with pre-emplacement testing, engineered barrier system (seals) testing, and environmental and 
disruptive events monitoring.  In addition, baseline development will be conducted for all test 
programs.
The current Performance Confirmation Plan (CRWMS M&O 2000v) will be revised to support 
the license application and will identify the testing and monitoring program in more detail, as 
well as incorporate the most recent regulations, the latest repository safety strategy, and the final 
license application design.
5.9	ESSENTIALLY COMPLETED ANALYTICAL TECHNIQUES AND 
ANALYTICAL TECHNIQUES REQUIRING SIGNIFICANT DEVELOPMENT 
(SCP SECTIONS 8.3.5.19 AND 8.3.5.20)
The SCP sections on essentially completed analytical techniques and on analytical techniques 
requiring significant development are covered together because of their interdependence and 
because techniques are available now for all processes to be modeled for a potential repository at 
Yucca Mountain (although model development and improvements are not yet completed as 
mentioned below and in other sections of this progress report).
Background and SCP Plans.  The SCP (DOE 1988) defined essentially completed analytical 
techniques as those that already exist and could be used, with little additional work or only 
minor modifications, to conduct performance assessment analyses.  This included computer 
codes that have not yet been fully verified and mathematical models that have not yet been 
validated for application to the conditions at Yucca Mountain.  Analytical techniques requiring 
significant development were those for which analysis approaches are still being formulated, 
solution methods are still being developed, or codes are still being written or tested.  The SCP 
listed computer codes that were considered essentially complete at the time the SCP was written.
Changes and Status.  Some of the computer codes listed in the SCP (DOE 1988) have been 
dropped in favor of others that reflect advances in understanding the conditions at Yucca 
Mountain, engineering design methods, numerical analyses techniques, and computer hardware 
capabilities.
The computer codes and versions that have been approved for use in activities subject to the 
Quality Assurance Requirements and Description (DOE 1998d) can be used for ESF and MGR 
design and for performance assessments in support of a license application.  To date, this has 
included principally computer codes that are being used in the ESF and MGR design; most of 
these are proprietary codes acquired from commercial vendors.
Approval of computer codes for use in activities subject to the Quality Assurance Requirements 
and Description (DOE 1998d) requires verification of the computer codes and control of the use 
of the codes in accordance with quality assurance procedures that implement the Quality 
Assurance Requirements and Description.  This approval does not require validation of the 
conceptual and mathematical models embedded in the computer codes.  According to the SCP 
(DOE 1988), verification studies are used to demonstrate that the numerical values produced by 
a computational procedure correspond to the mathematical formulas on which they are based.  
No change has occurred in this approach.
No documented plan exists at present for mathematical model validation.  To date, the approach 
has been generally to develop new mathematical models in parallel with experimental work (e.g., 
waste form and waste package barrier degradation models) and to attempt to replicate laboratory 
and field measurements with existing models (e.g., groundwater flow and contaminant transport 
models, including coupled thermal-hydrological models).  Additional, site-specific validation 
will be part of the performance confirmation program.  This validation will entail predicting 
natural and engineered barrier system conditions expected in the preclosure phase, measuring 
these conditions in the preclosure phase, comparing the predictions with the measurements, and 
evaluating the validity of the models accordingly.  This approach is considered adequate to 
establish the validity of the mathematical models.
Future model development will consist principally of improving the currently used detailed 
process models to better represent conditions at Yucca Mountain as new site and laboratory data 
become available, developing new models to fill gaps identified by the new information, 
abstracting simplifications of the detailed process models for use in TSPAs, and integrating the 
abstractions into the TSPA approach and software.  This process was documented in the TSPA 
plan for the Viability Assessment (CRWMS M&O 1996k, Section 5) and will continue to be 
updated as work continues toward the license application.  In addition, model modifications or 
development may also be necessary to respond to changes in regulatory requirements.


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6.	REFERENCES
The references cited in the text are available for inspection at the DOE public reading room 
located at 1211 Town Center Drive, Las Vegas, Nevada, in open literature, or through 
proceedings volumes for symposia and technical conferences.  Technical reports and research 
products published by participating organizations on the Project may be obtained through the 
DOE Office of Civilian Radioactive Waste Management; the DOE Office of Scientific and 
Technical Information at Oak Ridge, Tennessee, which is the national center for dissemination of 
nonclassified scientific and technical information prepared from research sponsored by DOE; or 
the National Technical Information Service in Springfield, Virginia.  These documents may be 
ordered from:
Office of Civilian Radioactive Waste Management
National Inquiries Response Center
4101B Meadows Lane
Las Vegas, Nevada  89107
(800) 225-NWPA (6972)
Office of Scientific and Technical Information
U.S. Department of Energy
Post Office Box 62
Oak Ridge, TN  37831
(423) 576-8401
National Technical Information Service
U.S. Department of Commerce
5285 Port Royal Road
Springfield, VA  22161
(800) 553-6847
Of the listed Program and Project documents, readers may obtain only those documents that have 
been reviewed and approved by the DOE for public release.  Program and Project documents are 
identified by an accession number at the end of the reference, formatted primarily as 
MOL.########.####, though some have other prefixes (e.g., HQO or NNA).
Externally produced documents are identified with a six-digit catalog number assigned by the 
Project Technical Information Center.
NOTE:	Any draft documents cited in the following reference list are the best available source 
of the cited information.
6.1	DOCUMENTS CITED
Abrahamson, N.A. and Becker, A.M. 1996.  Estimation of Vibratory Ground Motion at Yucca 
Mountain.  Chapter 10 of Seismotectonic Framework and Characterization of Faulting at 
Yucca Mountain, Nevada.  Whitney, J.W., ed. Milestone 3GSH100M.  Denver, Colorado:  U.S. 
Geological Survey.  ACC:  MOL.19970129.0041.  TIC:  237980.  [DIRS 101419].
Ahlers, C.F.; Bandurraga, T.M.; Bodvarsson, G.S.; Chen, G.; Finsterle, S.; and Wu, Y.S. 1995.  
Summary of Model Calibration and Sensitivity Studies Using the LBNL/USGS Three-
Dimensional Unsaturated Zone Site-Scale Model.  Milestone 3GLM107M.  Berkeley, California:  
Lawrence Berkeley National Laboratory.  ACC:  MOL.19960208.0092.  [DIRS 101180]
Altman, S.J.; Arnold, B.W.; Barnard, R.W.; Barr, G.E.; Ho, C.K.; McKenna, S.A.; and Eaton, 
R.R. 1996.  Flow Calculations for Yucca Mountain Groundwater Travel Time (GWTT-95).  
SAND96-0819.  Albuquerque, New Mexico:  Sandia National Laboratories.  
ACC:  MOL.19961209.0152.  [DIRS 100591]
Arnold, B.W.; Altman, S.J.; Robey, T.H.; Barnard, R.W.; and Brown, T.J. 1995.  Unsaturated-
Zone Fast-Path Flow Calculations for Yucca Mountain Groundwater Travel Time Analyses 
(GWTT-94).  SAND95-0857.  Albuquerque, New Mexico:  Sandia National Laboratories.  
ACC:  MOL.19960327.0336.  [DIRS 101423]
Atkins, J.E. and Lee, J.H. 1996.  Users Guide to Waste Package Degradation (WAPDEG) 
Simulation Code, Version 1.0.  Las Vegas, Nevada:  Civilian Radioactive Waste Management 
System Management and Operating Contractor.  TIC:  233426.  [DIRS 130710]
Barnard, R.W.; Wilson, M.L.; Dockery, H.A.; Gauthier, J.H.; Kaplan, P.G.; Eaton, R.R.; 
Bingham, F.W.; and Robey, T.H. 1992.  TSPA 1991:  An Initial Total-System Performance 
Assessment for Yucca Mountain.  SAND91-2795.  Albuquerque, New Mexico:  Sandia National 
Laboratories.  ACC:  NNA.19920630.0033. [DIRS 100309]
Barr, G.E.; Borns, D.J.; and Fridrich, C. 1996.  Scenarios Constructed for the Effects of the 
Tectonic Processes on the Potential Nuclear Waste Repository at Yucca Mountain.  SAND96-
1132.  Albuquerque, New Mexico:  Sandia National Laboratories.  ACC:  MOL.19970610.0644.  
[DIRS 100301]
Benton, H.A. 1993.  "Operational Considerations in Drift Emplacement of Waste Packages."  
High Level Radioactive Waste Management:  Proceedings of the Fourth Annual International 
Conference, Las Vegas, Nevada, April 26-30, 1993.  1, 544-550. La Grange Park, Illinois: 
American Nuclear Society.  TIC: 208542.  [DIRS 157347]
Bish, D.L. and Chipera, S.J. 1994.  Long-Term Steam Heating of Tuffaceous Rocks.  Milestone 
4010.  [Los Alamos, New Mexico]:  Los Alamos National Laboratory.  TIC:  241288. 
[DIRS 130724]
Blakely, R.J.; Langenheim, V.E.; Ponce, D.A.; and Dixon, G.L. 2000.  Aeromagnetic Survey of 
the Amargosa Desert, Nevada and California:  A Tool for Understanding Near-Surface Geology 
and Hydrology.  Open-File Report 00-188.  [Denver, Colorado]:  U.S. Geological Survey.  
TIC:  248767.  [DIRS 151881].
Blanton, J.O., III 1992.  Nevada Test Site Flood Inundation Study, Part of U.S. Geological 
Survey Flood Potential and Debris Hazard Study, Yucca Mountain Site for United States 
Department of Energy, Office of Civilian Radioactive Waste Management.  Denver, Colorado:  
U.S. Department of the Interior, Bureau of Reclamation.  ACC: MOL.20010724.0302.  
[DIRS 100530]
Bodvarsson, G.S. and Bandurraga, T.M., eds. 1996.  Development and Calibration of the Three-
Dimensional Site-Scale Unsaturated Zone Model of Yucca Mountain, Nevada.  LBNL-39315.  
Berkeley, California:  Lawrence Berkeley National Laboratory.  ACC:  MOL.19970701.0692.  
[DIRS 100102]. [DIRS 100102]
Bodvarsson, G.S.; Bandurraga, T.M.; and Wu, Y.S., eds. 1997.  The Site-Scale Unsaturated Zone 
Model of Yucca Mountain, Nevada, for the Viability Assessment.  LBNL-40376.  Berkeley, 
California:  Lawrence Berkeley National Laboratory.  ACC: MOL.19971014.0232.  
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Boyd, P.J.; Noel, J.S.; Hill, T.N.; and Martin, R.J. 1996.  Unconfined Compression Tests on 
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6.2	CODES, STANDARDS, AND REGULATIONS
10 CFR (Code of Federal Regulations) 20.  1997.  Energy:  Standards for Protection Against 
Radiation.  Washington, D.C.:  U.S. Government Printing Office.  TIC:  239489.
10 CFR 60.  1997.  Energy:  Disposal of High-Level Radioactive Wastes in Geologic 
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157375]
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Nuclear Waste Repositories.  Washington, D.C.:  U.S. Government Printing Office.  
TIC:  222719.
30 CFR  1998.  Mineral Resources.  Washington, D.C.:  U.S. Government Printing Office.  
TIC:  240369.
40 CFR 191.  1993.  Protection of Environment:  Environmental Radiation Protection Standards 
for Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive 
Wastes.  Washington, D.C.:  U.S. Government Printing Office.  TIC:  238620.
61 FR (Federal Register) 66158.  1996.  Notice of Proposed Rulemaking and Public Hearing, 
10 CFR Part 960, General Guidelines for the Recommendation of Sites for Nuclear Waste 
Repositories.  Washington, D.C.:  U.S. Government Printing Office.  TIC:  240371.
64 FR 8640.  Disposal of High-Level Radioactive Wastes in a Proposed Geologic Repository at 
Yucca Mountain.  Proposed Rule:  10 CFR 63.  TIC:  242725.  [DIRS 132247].
64 FR 46976.  Environmental Radiation Protection Standards for Yucca Mountain, Nevada.  
Proposed Rule:  40 CFR 197.  TIC:  245374.
66 FR 32074.  40 CFR Part 197, Public Health and Environmental Radiation Protection 
Standards for Yucca Mountain, NV; Final Rule.  Readily available.  [DIRS 155216]
66 FR 57298.  Office of Civilian Radioactive Waste Management; General Guidelines for the 
Recommendation of Sites for Nuclear Waste Repositories; Yucca Mountain Site Suitability 
Guidelines. Final Rule 10 CFR Part 963.  Readily available.  [DIRS 156908]
64 FR 67054.  Office of Civilian Radioactive Waste Management; General Guidelines for the 
Recommendation of Sites for Nuclear Waste Repositories; Yucca Mountain Site Suitability 
Guidelines.  Proposed rule 10 CFR Part 963.  Readily available.  [DIRS 124756].
66 FR 55732.  Disposal of High-Level Radioactive Wastes in a Proposed Geologic Repository at 
Yucca Mountain, NV.  Final Rule 10 CFR Part 63.  Readily available.  [DIRS 156671].
Energy Policy Act of 1992.  42 U.S.C. 13201 et seq.  Readily available.
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U.S. Government Printing Office.  TIC:  241722.  [DIRS 101681].
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