LEFT INTENTIONALLY BLANK 

1. PURPOSE..............................................................................................................................13 
1.1 SCOPE..............................................................................................................................14 
1.2 FEP ANALYSISBACKGROUND................................................................................14 
1.2.1 FEP Identification and Screening...............................................................................14 
1.2.2 Integration of SZ FEP Screening into the TSPA-LA FEP Database..........................42 
2. QUALITY ASSURANCE.....................................................................................................43 
3. USE OF COMPUTER SOFTWARE...................................................................................45 
4. INPUTS..................................................................................................................................47 
4.1 DATA AND PARAMETERS...........................................................................................47 
4.2 CRITERIA........................................................................................................................62 
4.2.1 Acceptance Criterion for FEP Identification..............................................................62 
4.2.2 Acceptance Criterion for FEP Screening....................................................................62 
4.3 REGULATORY BASIS FOR NRC GUIDANCE............................................................63 
4.3.1 Low-Probability Criterion...........................................................................................63 
4.3.2 Low-Consequence Criteria.........................................................................................64 
4.3.3 By-Regulation Criteria................................................................................................65 
4.4 CODES AND STANDARDS............................................................................................68 
5. ASSUMPTIONS....................................................................................................................69 
5.1 ASHFALL LEACHING AND SZ TRANSPORT............................................................69 
5.2 PROBABILITY CRITERION...........................................................................................69 
5.3 EVOLUTION OF THE GEOLOGIC SETTING AND CLIMATE..................................70 
6. ANALYSIS............................................................................................................................71 
6.1 APPROACH......................................................................................................................71 
6.2 ANALYSIS OF SZ FEPS..................................................................................................72 
6.2.1 Fractures (1.2.02.01.0A).............................................................................................72 
6.2.2 Faults (1.2.02.02.0A)..................................................................................................73 
6.2.3 Igneous Activity Changes Rock Properties (1.2.04.02.0A)........................................75 
6.2.4 Ash Redistribution in Groundwater (1.2.04.07.0B)....................................................77 
6.2.5 Hydrothermal Activity (1.2.06.00.0A).......................................................................84 
6.2.6 Large-Scale Dissolution (1.2.09.02.0A).....................................................................85 
6.2.7 Hydrologic Response to Seismic Activity (1.2.10.01.0A)..........................................86 
6.2.8 Hydrologic Response to Igneous Activity (1.2.10.02.0A)..........................................91 
6.2.9 Water Table Decline (1.3.07.01.0A)...........................................................................92 
6.2.10 Water Table Rise Affects SZ (1.3.07.02.0A)............................................................95 
6.2.11 Water Management Activities (1.4.07.01.0A)..........................................................96 
6.2.12 Wells (1.4.07.02.0A).................................................................................................97 
6.2.13 Transport of Particles Larger Than Colloids in the SZ (2.1.09.21.0B)....................97 
6.2.14 Stratigraphy (2.2.03.01.0A)....................................................................................100 
6.2.15 Rock Properties of Host Rock and Other Units (2.2.03.02.0A).............................101 
6.2.16 Seismic Activity Changes Porosity and Permeability of Rock (2.2.06.01.0A)......103 
6.2.17 Seismic Activity Changes Porosity and Permeability of Faults (2.2.06.02.0A)....106
6.2.18 Seismic Activity Changes Porosity and Permeability of Fractures (2.2.06.02.0B)111 
6.2.19 Saturated Groundwater Flow in the Geosphere (2.2.07.12.0A).............................114 
6.2.20 Water-Conducting Features in the SZ (2.2.07.13.0A)............................................115 
6.2.21 Chemically-Induced Density Effects on Groundwater Flow (2.2.07.14.0A).........119 
6.2.22 Advection and Dispersion in the SZ (2.2.07.15.0A)...............................................119 
6.2.23 Dilution of Radionuclides in Groundwater (2.2.07.16.0A)....................................121 
6.2.24 Diffusion in the SZ (2.2.07.17.0A).........................................................................121 
6.2.25 Chemical Characteristics of Groundwater in the SZ (2.2.08.01.0A)......................122 
6.2.26 Geochemical Interactions and Evolution in the SZ (2.2.08.03.0A)........................124 
6.2.27 Complexation in the SZ (2.2.08.06.0A)..................................................................127 
6.2.28 Radionuclide Solubility Limits in the SZ (2.2.08.07.0A).......................................128 
6.2.29 Matrix Diffusion in the SZ (2.2.08.08.0A).............................................................128 
6.2.30 Sorption in the SZ (2.2.08.09.0A)...........................................................................130 
6.2.31 Colloidal Transport in the SZ (2.2.08.10.0A).........................................................132 
6.2.32 Groundwater Discharge to Surface Within the Reference Biosphere (2.2.08.11.0A)
...............................................................................................................................133 
6.2.33 Microbial Activity in the SZ (2.2.09.01.0A)..........................................................134 
6.2.34 Thermal Convection Cell Develops in SZ (2.2.10.02.0A).....................................135 
6.2.35 Natural Geothermal Effects on Flow in the SZ (2.2.10.03.0A)..............................136 
6.2.36 Thermo-Mechanical Stresses Alter Characteristics of Fractures Near Repository 
(2.2.10.04.0A)........................................................................................................137 
6.2.37 Thermo-Mechanical Stresses Alter Characteristics of Faults Near Repository 
(2.2.10.04.0B)........................................................................................................139 
6.2.38 Thermo-Mechanical Stresses Alter Characteristics of Rocks Above and Below the 
Repository (2.2.10.05.0A).....................................................................................140 
6.2.39 Thermo-Chemical Alteration in the SZ (Solubility, Speciation, Phase Changes, 
Precipitation/Dissolution) (2.2.10.08.0A)..............................................................141 
6.2.40 Repository-Induced Thermal Effects on Flow in the SZ (2.2.10.13.0A)...............143 
6.2.41 Gas Effects in the SZ (2.2.11.01.0A)......................................................................145 
6.2.42 Undetected Features in the SZ (2.2.12.00.0B)........................................................146 
6.2.43 Groundwater Discharge to Surface Outside the Reference Biosphere (2.3.11.04.0A)
...............................................................................................................................147 
6.2.44 Radioactive Decay and Ingrowth (3.1.01.01.0A)...................................................148 
6.2.45 Isotopic Dilution (3.2.07.01.0A).............................................................................149 
6.2.46 Recycling of Accumulated Radionuclides from Soils to Groundwater (1.4.07.03.0A)
...............................................................................................................................150 
7. CONCLUSIONS..................................................................................................................152 
7.1 SATURATED ZONE SCREENED FEPS......................................................................152 
8. INPUTS AND REFERENCES...........................................................................................155 
8.1 DOCUMENTS CITED....................................................................................................155 
8.2 PROCEDURES AND GUIDANCE................................................................................162 
8.3 CODES AND REGULATIONS......................................................................................163 

FIGURES 
Page 
Figure 1.2-1. Development and Screening Process for FEPs Related to the Saturated 
Zone.......................................................................................................................30 
Figure 6.2-1. Cross-Section Diagram of Simplified One-Dimensional Model for 
Transport in the SZ of Radionuclides Leached from Volcanic Ash......................80 
Figure 6.2-2. Example of Idealized Radionuclide Mass Breakthrough Curves at 18-km 
Distance Resulting from Volcanic Ash Leaching for Non-Sorbing and 
Sorbing Radionuclides...........................................................................................81 
Figure 6.2-3. Geologic Features in the Area of the Site-Scale Flow Model (from BSC 
2003 [166262], Figure 19)...................................................................................118 
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TABLES 
Page 
Table 1.2-1. SZ FEPs Considered in the TSPA-SR and TSPA-LA and Changes Between 
the Two Lists.............................................................................................................16 
Table 1.2-2. Included Saturated Zone FEPs.................................................................................31 
Table 1.2-3. Excluded Saturated Zone FEPs................................................................................36 
Table 4.1-1. Input Data for Included SZ FEPs.............................................................................48 
Table 4.1-2. Input Data for Excluded SZ FEPs............................................................................49 
Table 4.1-3. Other Regulations Used in This FEP AMR.............................................................61 
Table 6.2-1. Screening Estimate of Dose from the SZ for Leaching from Volcanic Ash, 
Conditional on Eruptive Release..............................................................................83 
Table 6.2-2. Summary of the SZ Sampled Parameters Specific to Radionuclide (RN) 
Sorption...................................................................................................................132 
Table 7.1-1. Summary of SZ FEPs Screening............................................................................152 

LEFT INTENTIONALLY BLANK 

ACRONYMS AND ABBREVIATIONS 
1-D One-Dimensional 
Am americium 
AMR Analysis Model Report 
ATC Alluvial Tracer Complex 
atm atmosphere 
BDCF Biosphere Dose Conversion Factor 
BSC Bechtel SAIC Company 
C centigrade 
CA California 
CDF cumulative distribution function 
CFR Code of Federal Regulations 
cm centimeter 
COLVO Colloid Retardation in the Volcanics (a sampled parameter used in the SZFT 
models) 
CORAL Colloid Retardation Factor in the Alluvium 
CORVO Colloid Retardation Factor in Volcanic Units 
CRWMS M&O Civilian Radioactive Waste Management System Management and Operating 
Contractor 
Cs cesium 
CSNF commercial spent nuclear fuel 
DCVO Diffusion Coefficient in Volcanics 
DE disruptive event 
DIRS Document Input Reference System 
DOE U. S. Department of Energy 
DTN Data Tracking Number 
Dw water density 
EBS Engineered Barrier System 
Eh electrode potential 
EPA Environmental Protection Agency 
ESF Exploratory Studies Facility 
FEP Feature, Event, and Process 
FISVO Flowing Interval Spacing in the Volcanic Units (a sampled parameter used in 
the SZFT models) 
FPVO Flowing Interval Porosity (sampled parameter used in the SZFT models) 
FPLAW western boundary of the alluvial uncertainty zone 
FPLAN northern boundary of the alluvial uncertainty zone 

ACRONYMS AND ABBREVIATIONS (Continued) 
GWSPD scaling parameter for groundwater specific discharge (a sampled parameter 
used in the SZFT models) 
HAVO Horizontal Anisotropy in the Volcanic Units (a sampled parameter used in the 
SZFT models) 
HFM Hydrogeologic Framework Model 
ka thousand years 
Kd sorption coefficient 
km kilometer 
LA License Application 
LANL Los Alamos National Laboratory 
LDISP Longitudinal Dispersivity (sampled parameter used in the SZFT models) 
m meter 
m.y.a. million years ago 
ml milliliter 
N/A Not Applicable 
Np neptunium 
NRC Nuclear Regulatory Commission or National Research Council 
NTS Nevada Test Site 
OCRWM Office of Civilian Radioactive Waste Management 
ORD Office of Repository Development 
Pa protactinium 
PA Performance Assessment 
Pd particle density 
PSHA Probabilistic Seismic Hazard Analysis 
Pu plutonium 
QA Quality Assurance 
QARD Quality Assurance Requirements and Description 
Ra radium 
RMEI Reasonably Maximally Exposed Individual 
RN radionuclide 
SAR Safety Analysis Report 
SNL Sandia National Laboratories 
SR Site Recommendation 

ACRONYMS AND ABBREVIATIONS (Continued) 
STN software tracking number 
sv settling velocity 
SZ saturated zone 
SZFT Saturated Zone Flow and Transport 
Tc technetium 
Th thorium 
THC Thermal-Hydrologic-Chemical 
TSPA Total System Performance Assessment 
U uranium 
USGS United States Geological Survey 
UZ unsaturated zone 
WF waste form 
YM Yucca Mountain 
YMP Yucca Mountain Project 

LEFT INTENTIONALLY BLANK 

1. PURPOSE 
The U.S. Department of Energy (DOE) must provide a reasonable assurance that the 
performance objectives for the Office of Repository Development (ORD) radioactive-waste 
repository can be achieved for a 10,000-year post-closure period. The guidance that mandates 
this direction is under the provisions of the Code of Federal Regulations 10 CFR Part 63 
[156605] (Nuclear Regulatory Commission (NRC) regulations governing Yucca Mountain). 
This assurance must be demonstrated in the form of a performance assessment (PA). From 10 
CFR Part 63.2, the definition of performance assessment means an analysis that: 
1. Identifies the features, events, processes (except human intrusion), and sequences of 
events and processes (except human intrusion) that might affect the Yucca Mountain 
disposal system and their probabilities of occurring during 10,000 years after disposal; 
2. Examines the effects of those features, events, processes, and sequences of events and 
processes upon the performance of the Yucca Mountain disposal system; and 
3. Estimates the dose incurred by the reasonably maximally exposed individual, 
including the associated uncertainties, as a result of releases caused by all significant 
features, events, processes, and sequences of events and processes, weighted by their 
probability of occurrence. 
To demonstrate that regulatory-specified performance objectives of 10 CFR Part 63.2 [156605] 
can be achieved for a 10,000-year post-closure period, the ORD is implementing a Features, 
Events, Processes (FEP) analysis and scenario development methodology based on the work of 
Cranwell et al. (1990 [101234]). The methodology, incorporated into a Total System 
Performance Assessment (TSPA), provides a systematic approach for considering, as completely 
as practical, the possible future state of a repository system. The TSPA seeks to span the set of 
all possible future states using a finite set of scenario classes. A scenario is a well-defined, 
connected sequence of FEPs that is an outline of a possible future condition of the proposed 
repository system. A scenario class is a set of related scenarios sharing sufficient similarities that 
they can usefully be aggregated for the purposes of screening or analysis. The objective of FEP 
analysis and scenario development is to define a limited set of scenario classes and scenarios that 
can reasonably be analyzed quantitatively while still maintaining comprehensive coverage of the 
range of possible future states of the disposal system. 
Thus, FEPs are a fundamental aspect of a PA, where (1) a feature is an object, structure, or 
condition that has a potential to affect disposal system performance, (2) an event is a natural or 
human-caused phenomenon that has a potential to affect disposal system performance and that 
occurs during an interval that is short compared to the period of performance, and (3) a process 
is a natural or human-caused phenomenon that has a potential to affect disposal system 
performance and that operates during all or a significant part of the period of performance. 
Identifying FEPs that are potentially relevant to the functioning of the disposal system 
conceptually produces the initial domain or parameter space of the model of the disposal system, 
and a screening process omits those portions of the domain that are not pertinent. When 
developing the conceptual model of the disposal system, the formal and defensible selection of 
the pertinent domain of FEPs is one aspect that sets PAs apart from typical scientific or 

engineering analyses. Because of the nature of FEP screening and model development, several 
iterations of the PA process are potentially necessary, both to eliminate those FEPs of negligible 
influence and to improve the modeling of those retained FEPs. 
This scientific analysis report focuses on FEP analysis of saturated-zone (SZ) FEPs to be 
considered in the TSPA model for the license application (LA). 
1.1 SCOPE 
This scientific analysis report is governed by the Office of Civilian Radioactive Waste 
Management (OCRWM) Technical Work Plan for: Saturated Zone Flow and Transport 
Modeling and Testing Technical Work Plan TWP-NBS-MD-000002 Rev 01 ICN 01 (BSC 2003 
[166034], Section 2.7), Work Package ASZM04. 
This report has a two-fold scope: 
1. It gives the TSPA-LA disposition (i.e., how the FEP is implemented) for 21 SZ FEPs to 
be included in the TSPA-LA analysis model and relates them to the scientific analyses 
reports or model reports in which these dispositions are developed and documented. 
2. It documents the screening argument (i.e., technical basis and rationale) for the 25 SZ 
FEPs that are excluded from the TSPA-LA analysis based on the criteria specified in 10 
CFR Part 63 [156605]. These criteria are identified in Section 4.3 of this report. 
The scope of this report also provides evidence for the acceptance criteria as specified in the 
Yucca Mountain Review Plan, Final Report (NRC 2003 [163274], Section 2.2.1.2.1.3) and 
summarized in Section 4.2 of this report. 
1.2 FEP ANALYSISBACKGROUND 
1.2.1 FEP Identification and Screening 
The development of a comprehensive list of FEPs potentially relevant to post-closure 
performance of the Yucca Mountain repository is an ongoing, iterative process based on site-
specific information, design, and regulations. The first step of the FEP analysis process is the 
identification of FEPs potentially relevant to the performance of the potential Yucca Mountain 
repository. An initial list of FEPs relevant to Yucca Mountain was developed from a 
comprehensive list of FEPs from radioactive waste disposal programs in other countries (BSC 
2001 [154365], Section 2.1) and was supplemented with additional Yucca Mountain Project 
(YMP)-specific FEPs from project literature, technical workshops, and reviews (Freeze et al. 
2001 [154365], Sections 2.2 through 2.4). The initial FEP list contained 328 FEPs, of which 176 
were included in TSPA-Site Recommendation (SR) models (Total System Performance 
Assessment for the Site Recommendation, CRWMS M&O 2000 [153246], Tables B-9 through B-
17). 
For TSPA-LA, FEP analysis included a reorganization and re-evaluation of the FEP list in 
accordance with The Enhanced Plan for Features Events and Processes (FEPs) at Yucca 

Mountain (BSC 2002 [158966], Section 3.2) and the Key Technical Issue Letter Report 
Response to Additional Information Needs on TSPAI 2.05 and TSPAI 2.06 REG-WIS-PA-
000003 REV 00 ICN 04 (Freeze 2003 [165394]). The reorganization and re-evaluation resulted 
in a preliminary list of SZ FEPs as extracted from the preliminary TSPA-LA FEP list (Data 
Tracking Number (DTN): MO0307SEPFEPS4.000 [164527]). Further evaluation by 
knowledgeable SZ subject-matter experts resulted in subsequent changes from the preliminary 
TSPA-LA FEP list. The result was a list of 46 SZ FEPs, as identified in Table 1.2-1. Table 1.2-
1 summarizes the changes from TSPA-SR to the FEP organization and descriptions being used 
for TSPA-LA that appear in this report. Changes made subsequent to the preliminary TSPA-LA 
FEP list (DTN: MO0307SEPFEPS4.000 [164527]) are identified with italicized text. 

Table 1.2-1. SZ FEPs Considered in the TSPA-SR and TSPA-LA and Changes Between the Two Lists 
TSPA-SR FEP Name and Description 
TSPA-LA FEP Name and Description 
Change from SR to LA a 
1.2.02.01.00 Fractures 
Groundwater flow in the Yucca Mountain region 
and transport of any released radionuclides may 
take place along fractures. Transmissive fractures 
may be existing, reactivated, or newly formed 
fractures. The rate of flow and the extent of 
transport in fractures are influenced by 
characteristics such as orientation, aperture, 
asperity, fracture length, connectivity, and the 
nature of any linings or infills. Generation of new 
fractures and reactivation of preexisting fractures 
may significantly change the flow and transport 
paths. Newly formed and reactivated fractures 
typically result from thermal, seismic, or tectonic 
events. 
1.2.02.01.0A Fractures 
Groundwater flow in the Yucca Mountain region and 
transport of any released radionuclides may take 
place along fractures. The rate of flow and the extent 
of transport in fractures are influenced by 
characteristics such as orientation, aperture, asperity, 
fracture length, connectivity, and the nature of any 
linings or infills. 
This FEP now addresses existing fractures. 
Changes to fractures are moved to 2.2.10.04.0A 
(thermal) and 2.2.06.02.0B (seismic). 
1.2.02.02.00 Faulting 
Faulting may occur due to sudden major changes 
in the stress situation (e.g. seismic activity) or due 
to slow motions in the rock mass (e.g., tectonic 
activity). Movement along existing fractures and 
faults is more likely than the formation of new 
faults. Faulting may alter the rock permeability in 
the rock mass and alter or short-circuit the flow 
paths and flow distributions close to the repository 
and create new pathways through the repository. 
New faults or the cavitation of existing faults may 
enhance the groundwater flow, thus decreasing the 
transport times for potentially released 
radionuclides. 
1.2.02.02.0A Faults 
Numerous faults of various sizes have been noted in 
the Yucca Mountain Region and in the repository 
area in specific. Faults may represent an alteration 
of the rock permeability and continuity of the rock 
mass, alteration or short-circuiting of the flow paths 
and flow distributions close to the repository, and 
represent unexpected pathways through the 
repository. 
Name changed to be consistent with fractures, 
FEP 1.2.02.01.0A. 
The FEP description has changed to focus on 
effects of existing faults and how incorporated 
into the models. 
Changes to faults were moved to 2.2.10.04.0B 
(thermal) and 2.2.06.02.0A (seismic). 
(Minor typo in description corrected.) 

Table 1.2-1. SZ FEPs Considered in the TSPA-SR and TSPA-LA and Changes Between the Two Lists (Continued) 
TSPA-SR FEP Name and Description 
TSPA-LA FEP Name and Description 
Change from SR to LA a 
1.2.03.01.00 Seismic Activity 
Seismic activity (i.e., earthquakes) could produce 
jointed-rock motion, rapid fault growth, slow fault 
growth or new fault formation, resulting in changes 
in hydraulic heads, changes in groundwater 
recharge or discharge zones, changes in rock 
stresses, and severe disruption of the integrity of 
the drifts (e.g., vibration damage, rockfall). 
Not applicable  Not assigned to SZ for LA 
This FEP was deleted because it was redundant 
to other seismic FEPs. 
1.2.04.02.00 Igneous Activity Causes Changes 
to Rock Properties 
Igneous activity near the underground facility 
causes extreme changes to rock hydrologic and 
mineralogic properties. Permeabilities of dikes and 
sills and the heated regions immediately around 
them can differ from those of country rock. Mineral 
alterations can also change the chemical response 
to contaminants. 
1.2.04.02.0A Igneous activity changes rock 
properties 
Igneous activity near the underground facility causes 
extreme changes in rock stress and the thermal 
regime, and may lead to rock deformation, including 
activation, creation, and sealing of faults and 
fractures. This may cause changes in the rock 
hydrologic and mineralogic properties. Permeabilities 
of dikes and sills and the heated regions immediately 
around them can differ from those of country rock. 
Mineral alterations can also change the chemical 
response of the host rock to contaminants. 
FEP description modified to address concerns 
with thermal changes due to intrusion and to 
clarify that chemical response of host rock is an 
issue. 
1.2.04.07.00 Ashfall 
Finely divided waste particles are carried up a 
volcanic vent and deposited on the surface from an 
ash cloud or pyroclastic flow. 
1.2.04.07.0B Ash redistribution in groundwater 
Following deposition of contaminated ash on the 
surface, contaminants may leach out of the ash 
deposit and be transported through the subsurface to 
the compliance point. 
This FEP was split into three to address direct 
exposure from ashfall (A), redistribution of ash 
via groundwater (B), and redistribution of ash via 
surface transport mechanisms (C). Only 
1.2.04.07.0B is addressed in this report. 
1.2.06.00.00 Hydrothermal Activity 
This category contains FEPs associated with 
naturally-occurring high-temperature groundwater, 
including processes such as density-driven 
groundwater flow and hydrothermal alteration of 
minerals in the rocks through which the high-
temperature groundwater flows. 
1.2.06.00.0A Hydrothermal activity 
Naturally-occurring high-temperature groundwater 
may induce hydrothermal alteration of minerals in the 
rocks through which the high-temperature 
groundwater flows. 
Description edited for clarity. 

1.2.09.02.00 Large-scale Dissolution 
Dissolution can occur when any soluble mineral is 
removed by flowing water, and large-scale 
dissolution is a potentially important process in 
rocks that are composed predominantly of water-
soluble evaporite minerals, such as salt. 
1.2.09.02.0A Large-scale dissolution 
Dissolution can occur when any soluble mineral is 
removed by flowing water, and large-scale dissolution 
is a potentially important process in rocks that are 
composed predominantly of water-soluble evaporite 
minerals, such as salt. 
No change. 
1.2.10.01.00 Hydrologic Response to Seismic 
Activity 
Seismic activity, associated with fault movement, 
may create new or enhanced flow pathways and/or 
connections between stratigraphic units, or it may 
change the stress (and therefore fluid pressure) 
within the rock. These responses have the 
potential to significantly change the surface and 
groundwater flow directions, water level, water 
chemistry and temperature. 
1.2.10.01.0A Hydrologic response to seismic 
activity 
Seismic activity, associated with fault movement, may 
create new or enhanced flow pathways and/or 
connections between stratigraphic units, or it may 
change the stress (and therefore fluid pressure) 
within the rock. These responses have the potential 
to significantly change the surface- and groundwater-
flow directions, water level, water chemistry, and 
temperature. 
Name changed to Hydrologic from 
Hydrological. 
1.2.10.02.00 Hydrologic Response to Igneous 
Activity 
Igneous activity may change the groundwater flow 
directions, water level, water chemistry and 
temperature. Igneous activity includes magmatic 
intrusions, which may change rock properties and 
flow pathways, and thermal effects which may heat 
up groundwater and rock. 
1.2.10.02.0A Hydrologic response to igneous 
activity 
Igneous activity includes magmatic intrusions which 
may alter groundwater flow pathways, and thermal 
effects which may heat up groundwater and rock. 
Igneous activity may change the groundwater flow 
directions, water level, water chemistry, and 
temperature. Eruptive and extrusive phases may 
change the topography, surface drainage patterns, 
and surface soil conditions. This may affect 
infiltration rates and locations. 
FEP description modified to more clearly identify 
potential for hydrologic response due to surface 
effects of igneous activity. 
1.3.07.01.00 Drought/Water Table Decline 
Climate change could produce an extended 
drought, leading to a decline in the water table in 
the saturated zone, which would affect the release 
and exposure pathways from the repository. 
1.3.07.01.0A Water table decline 
Climate change could produce decreased infiltration 
(e.g., an extended drought), leading to a decline in 
the water table in the saturated zone, which would 
affect the release and exposure pathways from the 
repository. 
Name and description edited for clarity. 
Potential deleted from description, no longer a 
potential repository. 

1.3.07.02.00 Water Table Rise 
Climate change could produce increased 
infiltration, leading to a rise in the regional water 
table, possibly affecting the release and exposure 
pathways from the repository. A regionally higher 
water table and change in flow patterns might 
move discharge points closer to the repository, or 
flood the repository. 
1.3.07.02.0A Water table rise affects SZ 
Climate change could produce increased infiltration, 
leading to a rise in the regional water table, possibly 
affecting the release and exposure from the 
repository by altering flow and transport pathways in 
the SZ. A regionally higher water table and change in 
SZ flow patterns might move discharge points closer 
to the repository. 
FEP split into SZ and Unsaturated Zone (UZ). 
Name and description edited to be SZ specific. 
Also, the word potential deleted from 
description, no longer a potential repository. 
1.4.07.01.00 Water Management Activities 
Water management is accomplished through a 
combination of dams, reservoirs, canals, pipelines, 
and collection and storage facilities. Water 
management activities could have a major 
influence on the behavior and transport of 
contaminants in the biosphere. 
1.4.07.01.0A Water management activities 
Water management is accomplished through a 
combination of dams, reservoirs, canals, pipelines, 
and collection and storage facilities. Water 
management activities could have a major influence 
on the behavior and transport of contaminants in the 
biosphere. 
No change. 
1.4.07.02.00 Wells 
One or more wells drilled for human use (e.g. 
drinking water, bathing) or agricultural use (e.g. 
irrigation, animal watering) may intersect the 
contaminant plume. 
1.4.07.02.0A Wells 
One or more wells drilled for human use (e.g. 
drinking water, bathing) or agricultural use (e.g. 
irrigation, animal watering) may intersect the 
contaminant plume. 
Recycling issue now addressed in 1.4.07.03.0A 
Not applicable (new FEP for TSPA-LA) 
1.4.07.03.0A Recycling of accumulated 
radionuclides from soils to groundwater 
Radionuclides that have accumulated in soils (e.g., 
from deposition of contaminated irrigation water) may 
leach out of the soil and be recycled back into the 
groundwater as a result of recharge (either from 
natural or agriculturally induced infiltration). The 
recycled radionuclides may lead to enhanced 
radionuclide exposure at the receptor. 
New FEP created to cover the recycling issue. 

2.1.09.21.00 Suspension of Particles Larger 
than Colloids 
Ground water flow through the waste could remove 
radionuclide-bearing particles by a rinse 
mechanism. Particles of radionuclide bearing 
material larger than colloids could then be 
transported in water flowing through the waste and 
Engineered Barrier System (EBS) by suspension. 
2.1.09.21.0B Transport of particles larger than 
colloids in the SZ 
Particles of radionuclide-bearing material larger than 
colloids could be entrained in suspension and then be 
transported in water flowing through the SZ. 
FEP split into EBS, UZ, and SZ. Name and 
description edited to be SZ specific. 
2.2.03.01.00 Stratigraphy 
Stratigraphic information is necessary information 
for the performance assessment. This information 
should include identification of the relevant rock 
units, soils and alluvium, and their thickness, lateral 
extents, and relationships to each other. Major 
discontinuities should be identified. 
2.2.03.01.0A Stratigraphy 
Stratigraphic information is necessary information for 
the performance assessment. This information 
should include identification of the relevant rock units, 
soils and alluvium, and their thickness, lateral 
extents, and relationships to each other. Major 
discontinuities should be identified. 
No change. 
2.2.03.02.00 Rock Properties of Host Rock and 
Other Units 
Physical properties such as porosity and 
permeability of the relevant rock units, soils, and 
alluvium are necessary for the performance 
assessment. Possible heterogeneities in these 
properties should be considered. 
2.2.03.02.0A Rock properties of host rock and 
other units 
Physical properties such as porosity and permeability 
of the relevant rock units, soils, and alluvium are 
necessary for the performance assessment. Possible 
heterogeneities in these properties should be 
considered. Questions concerning events and 
processes that may cause these physical properties 
to change over time are considered in other FEPs. 
Description edited for clarity. 
2.2.06.01.00 Changes in Stress Change Porosity 
and Permeability of Rock 
Changes in stress due to all causes, including 
heating, seismic activity, and regional tectonic 
activity, have a potential to result in strains that 
affect flow properties in rock outside the 
excavation-disturbed zone. 
(This FEP was not assigned to SZ for TSPA-
SR.) 
2.2.06.01.0A Seismic activity changes porosity 
and permeability of rock 
Seismic activity (fault displacement or vibratory 
ground motion) has a potential to change rock 
stresses and result in strains that affect flow 
properties in rock outside the excavation-disturbed 
zone. It could result in strains that alter the 
permeability in the rock matrix. These effects may 
decrease transport times for potentially released 
radionuclides. 
FEP Description modified to limit discussion in 
this FEP to seismic-related events. Thermal 
effects on rock stresses are covered in FEP 
2.2.10.05.0B. 
Minor typo in description corrected. 

2.2.06.02.00 Changes in Stress Produce Change 
in Permeability of Faults 
Stress changes due to thermal, tectonic and 
seismic processes result in strains that alter the 
permeability along and across faults. 
2.2.06.02.0A Seismic activity changes porosity 
and permeability of faults 
Seismic activity (fault displacement or vibratory 
ground motion) has a potential to produce jointed-
rock motion and change stress and strains that alter 
the permeability along faults. This could result in 
reactivation of preexisting faults or generate new 
faults and significantly change the flow and transport 
paths, alter or short-circuit the flow paths and flow 
distributions close to the repository, and create new 
pathways through the repository. These effects may 
decrease transport times for potentially released 
radionuclides. 
FEP Description modified to limit discussion in 
this FEP to seismic-related events. Due to the 
linkage between changes in stress, fault 
displacement, and change in fault 
characteristics, these aspects of faulting have 
been incorporated from the TSPA-SR FEP 
1.2.02.02.00 Faulting. Thermal effects on faults 
are covered in FEP 2.2.10.04.0B. 
Not Applicable (new FEP for TSPA-LA) 
2.2.06.02.0B Seismic activity changes porosity 
and permeability of fractures 
Seismic activity (fault displacement or vibratory 
ground motion) has a potential to change stress and 
strains that alter the permeability along fractures. 
This could result in reactivation of preexisting 
fractures or generation of new fractures. Generation 
of new fractures and reactivation of preexisting 
fractures may significantly change the flow and 
transport paths, alter or short-circuit the flow paths 
and flow distributions close to the repository and 
create new pathways through the repository. These 
effects may decrease transport times for potentially 
released radionuclides. 
New FEP created for consistent level of detail to 
address changes in fractures, similar to that for 
rocks and faults. This FEP Description limits 
discussion in this FEP to seismic-related events. 
Due to the linkage between changes in stress, 
fracturing, and changes in fractures 
characteristics, these aspects of fracturing have 
been incorporated from the TSPA-SR FEP 
1.2.02.01.00 Fractures. Thermal effects on 
fractures are covered in FEP 2.2.10.04.0A. 
2.2.06.03.00 Changes in Stress Alter Perched 
Water Zones 
Strain caused by stress changes from tectonic or 
seismic events alters the rock permeabilities that 
allow formation and persistence of perched water 
zones. 
Not applicable  Not assigned to SZ for LA 
This FEP is now assigned to Disruptive Event 
(DE) and UZ. 

2.2.07.12.00 Saturated Groundwater Flow 
Groundwater flow in the saturated zone below the 
water table may affect long-term performance of 
the repository. The location, magnitude, and 
direction of flow under present and future 
conditions and the hydraulic properties of the rock 
are all relevant. 
2.2.07.12.0A Saturated groundwater flow in the 
geosphere 
Groundwater flow in the saturated zone below the 
water table may affect long-term performance of the 
repository. The location, magnitude, and direction of 
flow under present and future conditions and the 
hydraulic properties of the rock are all relevant. 
Name changed, description changed to reflect 
that it is no longer a potential repository. 
2.2.07.13.00 Water-Conducting Features 
Geologic features in the saturated zone may affect 
groundwater flow by providing preferred pathways 
for flow. 
2.2.07.13.0A Water-conducting features in the SZ 
Geologic features in the saturated zone may affect 
groundwater flow by providing preferred pathways for 
flow. 
Name changed. 
2.2.07.14.00 Density Effects on Groundwater 
Flow (Concentration) 
Spatial variation in groundwater density may affect 
groundwater flow. 
2.2.07.14.0A Chemically-induced density effects 
on groundwater flow 
Chemically-induced spatial variation in groundwater 
density may affect groundwater flow. 
Name and description edited to included 
chemically-induced. Thermally induced density 
effects are covered by 2.2.10.13.0A. 
2.2.07.15.00 Advection and Dispersion 
Advection and dispersion processes may affect 
contaminant transport in the saturated zone. 
2.2.07.15.0A Advection and dispersion in the SZ 
Advection and dispersion processes may affect 
contaminant transport in the SZ. 
Name changed. 
2.2.07.16.00 Dilution of Radionuclides in 
Groundwater 
Dilution due to mixing of contaminated and 
uncontaminated water may affect radionuclide 
concentrations in groundwater during transport in 
the saturated zone and during pumping at a 
withdrawal well 
2.2.07.16.0A Dilution of radionuclides in 
groundwater 
Dilution due to mixing of contaminated and 
uncontaminated water may affect radionuclide 
concentrations in groundwater during transport in the 
saturated zone and during pumping at a withdrawal 
well. 
No change. 
2.2.07.17.00 Diffusion 
Molecular diffusion processes may affect 
radionuclide transport in the saturated zone. 
2.2.07.17.0A Diffusion in the SZ 
Molecular diffusion processes may affect radionuclide 
transport in the SZ. 
Name changed. 

2.2.08.01.00 Groundwater 
Chemistry/Composition in UZ and SZ 
Chemistry and the characteristics of groundwater in 
the saturated and unsaturated zones may affect 
groundwater flow and radionuclide transport. 
Groundwater chemistry and other characteristics, 
including temperature, pH, Eh, ionic strength, and 
major ionic concentrations, may vary spatially 
throughout the system as a result of different rock 
mineralogy, and may also change through time, as 
a result of the evolution of the disposal system or 
from mixing with other waters. 
2.2.08.01.0A Chemical characteristics of 
groundwater in the SZ 
Chemistry and other characteristics of groundwater in 
the saturated zone may affect groundwater flow and 
radionuclide transport of dissolved and colloidal 
species. Groundwater chemistry and other 
characteristics, including temperature, pH, Eh, ionic 
strength, and major ionic concentrations, may vary 
spatially throughout the system as a result of different 
rock mineralogy. 
Split FEP into SZ and UZ. Name and description 
edited to be SZ specific. 
For LA, this FEP addresses ambient SZ 
chemistry and spatial variability in SZ chemistry. 
2.2.08.02.00 Radionuclide Transport in a Carrier 
Plume 
Radionuclide transport occurs in a carrier plume in 
the geosphere. Transport may be as dissolved or 
colloidal species, and transport may occur in both 
the unsaturated and saturated zone. 
Not applicable  Not assigned to SZ for LA 
This FEP was deleted because it was found to 
be redundant with SZ FEPs 2.2.08.01.0A and 
2.2.08.03.0A, and with UZ FEPs 2.2.08.01.0B 
and 2.2.08.03.0B. 
2.2.08.03.00 Geochemical Interactions in the 
Geosphere 
Geochemical interactions may lead to dissolution 
and precipitation of minerals along the groundwater 
flow path, affecting groundwater flow, rock 
properties, and sorption on contaminants. These 
interactions may result from the evolution of 
disposal system or from external processes such 
as weathering. Effects on hydrologic flow 
properties of the rock, radionuclide solubility, 
sorption processes, and colloidal transport are 
relevant. Kinetics of chemical reactions should be 
considered in the context of the time-scale of 
concern. 
2.2.08.03.0A Geochemical interactions and 
evolution in the SZ 
Groundwater chemistry and other characteristics, 
including temperature, pH, Eh, ionic strength, and 
major ionic concentrations, may change through time, 
as a result of the evolution of the disposal system or 
from mixing with other waters. Geochemical 
interactions may lead to dissolution and precipitation 
of minerals along the groundwater flow path, affecting 
groundwater flow, rock properties and sorption of 
contaminants. Effects on hydrologic flow properties 
of the rock, radionuclide solubilities, sorption 
processes, and colloidal transport are relevant. 
Kinetics of chemical reactions should be considered 
in the context of the time scale of concern. 
Split FEP into UZ and SZ. Name and description 
edited to be SZ specific. For LA, this FEP 
addresses changes to SZ chemistry over time. 

2.2.08.06.00 Complexation in the Geosphere 
Complexing agents such as humic and fulvic acids 
present in natural groundwater could affect 
radionuclide transport. 
2.2.08.06.0A Complexation in the SZ 
Complexing agents such as humic and fulvic acids 
present in natural groundwaters could affect 
radionuclide transport in the SZ. 
Split FEP into SZ and UZ. Name and description 
edited to be SZ specific. 
2.2.08.07.00 Radionuclide Solubility Limits in 
the Geosphere 
Solubility limits for radionuclides in geosphere 
groundwater may be different than in the water in 
the waste and EBS. 
2.2.08.07.0A Radionuclide solubility limits in the 
SZ 
Solubility limits for radionuclides may be different in 
saturated zone groundwater than in the water in the 
unsaturated zone or in the waste and EBS. 
Split FEP into SZ and UZ. Name and description 
edited to be SZ specific. 
2.2.08.08.00 Matrix Diffusion 
Matrix diffusion is the process by which 
radionuclides and other species transported by 
advective flow in fractures or other pathways move 
into the matrix of the porous rock by diffusion. 
Matrix diffusion can be a very efficient retarding 
mechanism, especially for strongly sorbed 
radionuclides due to the increase in rock surface 
accessible to sorption. 
2.2.08.08.0A Matrix diffusion in the SZ 
Matrix diffusion is the process by which radionuclides 
and other species transported in the SZ by advective 
flow in fractures or other pathways move into the 
matrix of the porous rock by diffusion. Matrix 
diffusion can be a very efficient retarding mechanism, 
especially for strongly sorbed radionuclides due to 
the increase in rock surface accessible to sorption. 
Split FEP into SZ and UZ. Name and description 
edited to be SZ specific. 
2.2.08.09.00 Sorption in the UZ and SZ 
Sorption of dissolved and colloidal radionuclides 
can occur on the surfaces of both fractures and 
matrix in rock or soil along the transport path. 
Sorption may be reversible or irreversible, and it 
may occur as a linear or nonlinear process. 
Sorption kinetics and the availability of sites for 
sorption should be considered. 
2.2.08.09.0A Sorption in the SZ 
Sorption of dissolved and colloidal radionuclides in 
the SZ can occur on the surfaces of both fractures 
and matrix in rock or soil along the transport path. 
Sorption may be reversible or irreversible, and it may 
occur as a linear or nonlinear process. Sorption 
kinetics and the availability of sites for sorption should 
be considered. Sorption is a function of the 
radioelement type, mineral type, and groundwater 
composition. 
Split FEP into SZ and UZ. Name and description 
edited to be SZ specific. 
2.2.08.10.00 Colloid Transport in the Geosphere 
Radionuclides may be transported in groundwater 
in the geosphere as colloidal species. Types of 
colloids include true colloids, pseudo colloids, and 
microbial colloids. 
2.2.08.10.0A Colloidal transport in the SZ 
Radionuclides may be transported in groundwater in 
the SZ as colloidal species. Types of colloids include 
true colloids, pseudo colloids, and microbial colloids. 
Split FEP into SZ and UZ. Name and description 
edited to be SZ specific. 

2.2.08.11.00 Distribution and Release Of 
Nuclides 
Radionuclides may be released to the biosphere 
following groundwater transport in unsaturated and 
saturated zones. 
2.2.08.11.0A Groundwater discharge to surface 
within the reference biosphere 
Radionuclides transported in groundwater as solutes 
or solid materials (colloids) from the far field may 
discharge at specific "entry" points that are within the 
reference biosphere. Natural surface discharge 
points, including those resulting from water table or 
capillary rise, may be surface water bodies (rivers, 
lakes), springs, wetlands, holding ponds, or 
unsaturated soils. 
For LA, only addresses natural discharge. Well 
discharge is in 1.4.07.01.0A and 1.4.07.02.0A. 
Corresponding changes to name and 
description. 
2.2.09.01.00 Microbial activity in Geosphere 
Microbial activity in the geosphere may affect 
radionuclide mobility in rock and soil through 
colloidal processes, by influencing the availability of 
complexing agents, or by influencing groundwater 
chemistry. 
2.2.09.01.0A Microbial activity in the SZ 
Microbial activity in the SZ may affect radionuclide 
mobility in rock and soil through colloidal processes, 
by influencing the availability of complexing agents, 
or by influencing groundwater chemistry. 
Split FEP into SZ and UZ. Name and description 
edited to be SZ specific. 
2.2.10.01.00 Repository Induced Thermal 
Effects in the Geosphere 
Thermal effects on groundwater density may cause 
changes in flow in the unsaturated and saturated 
zones. 
Not applicable  Not assigned to SZ for LA 
This FEP was changed to be UZ specific. 
2.2.10.13.0A now covers this information for the 
SZ. 
2.2.10.02.00 Thermal Convection Cell Develops 
in SZ 
Thermal effects due to waste emplacement result 
in convective flow in the saturated zone beneath 
the repository. 
2.2.10.02.0A Thermal convection cell develops in 
SZ 
Thermal effects due to waste emplacement result in 
convective flow in the saturated zone beneath the 
repository. 
Description edited; no longer a potential 
repository. 
2.2.10.03.00 Natural Geothermal Effects 
The existing geothermal gradient, and spatial or 
temporal variability in that gradient, may affect 
groundwater flow in the unsaturated and saturated 
zones. 
2.2.10.03.0A Natural geothermal effects on flow in 
the SZ 
The existing geothermal gradient, and spatial or 
temporal variability in that gradient, may affect 
groundwater flow in the SZ. 
Split FEP into SZ and UZ. Name and description 
edited to be SZ specific. 

2.2.10.04.00 Thermo-mechanical Alteration of 
Fractures Near Repository 
Heat from the waste causes thermal expansion of 
the surrounding rock, generating changes in the 
stress field that may change the material properties 
(both hydrologic and mechanical) of fractures in the 
rock. Cooling following the peak thermal period will 
also change the stress field, further affecting 
fracture properties near the repository. 
(This FEP was not assigned to SZ for TSPA-
SR.) 
2.2.10.04.0A Thermo-mechanical stresses alter 
characteristics of fractures near repository 
Heat from the waste causes thermal expansion of the 
surrounding rock, generating changes in the stress 
field that may change the fracture properties (both 
hydrologic and mechanical) of fractures in the rock. 
Cooling following the peak thermal period will also 
change the stress field, further affecting fracture 
properties near the repository. 
This FEP now includes text related to thermal 
effects on fractures in the UZ and SZ from 
TSPA-SR FEPs 2.2.06.01.00, 2.2.06.02.00, 
2.2.06.03.00, and 1.2.02.01.00. 
Not Applicable (new FEP for the TSPA-LA) 
2.2.10.04.0B Thermo-mechanical stresses alter 
characteristics of faults near repository 
Heat from the waste causes thermal expansion of the 
surrounding rock, generating changes to the stress 
field that may change the fault properties (both 
hydrologic and mechanical) in and along faults. 
Cooling following the peak thermal period will also 
change the stress field, further affecting fault 
properties near the repository. 
New FEP created for consistent level of detail to 
address thermal effects on faults, similar to that 
for rocks and fractures. This FEP includes text 
related to thermal effect on faults in the SZ and 
UZ from TSPA-SR FEPs 2.2.06.01.00, 
2.2.06.02.00, 2.2.06.03.00, and 1.2.02.02.00. 
2.2.10.05.00 Thermo-mechanical Alteration of 
Rocks Above and Below the Repository 
Thermal-mechanical compression at the repository 
produces tension-fracturing in the PTn and other 
units above the repository. These fractures alter 
unsaturated zone flow between the surface and the 
repository. Extreme fracturing may propagate to 
the surface, affecting infiltration. Thermal fracturing 
in rocks below the repository affects flow and 
radionuclide transport to the saturated zone. 
(This FEP was not assigned to SZ for TSPA-
SR.) 
2.2.10.05.0A Thermo-mechanical stresses alter 
characteristics of rocks above and below the 
repository 
Thermal-mechanical compression at the repository 
produces tension-fracturing in the PTn and other 
units above the repository. These fractures alter 
unsaturated zone flow between the surface and the 
repository. Extreme fracturing may propagate to the 
surface, affecting infiltration. Thermal fracturing in 
rocks below the repository affects flow and 
radionuclide transport to the saturated zone. 
This FEP now includes text related to thermal 
effects on rock properties in the UZ and SZ from 
TSPA-SR FEPs 2.2.06.01.00, 2.2.06.02.00, and 
2.2.06.03.00. 

2.2.10.06.00 Thermo-chemical Alteration 
Thermal and chemical processes related to the 
emplacement of waste in the repository may alter 
the hydrologic properties of the saturated zone. 
Precipitation of zeolites, silica, or calcite is a 
relevant process. 
Not applicable  Not assigned to SZ for LA 
This FEP was changed to be UZ specific. 
2.2.10.08.0A now covers this information for the 
SZ. 
2.2.10.07.00 Thermo-chemical Alteration of the 
Calico Hills unit 
Fracture pathways in the Calico Hills are altered by 
the thermal and chemical properties of the water 
flowing out of the repository. 
Not applicable  Not assigned to SZ for LA 
This is applicable to the UZ only. 
2.2.10.08.00 Thermo-chemical Alteration of the 
Saturated Zone (precipitation plugs primary 
porosity) 
Thermal and chemical processes related to the 
emplacement of waste in the repository may alter 
the hydrologic properties of the saturated zone. 
Precipitation of zeolites, silica, or calcite are 
relevant processes 
2.2.10.08.0A Thermo-chemical alteration in the SZ 
(solubility, speciation, phase changes, 
precipitation/dissolution) 
Thermal effects may affect radionuclide transport 
directly by causing changes in radionuclide speciation 
and solubility in the SZ, or, indirectly, by causing 
changes to host rock mineralogy that affect the flow 
path. Relevant processes include volume effects 
associated with silica phase changes, precipitation 
and dissolution of fracture filling minerals (including 
silica and calcite), and alteration of zeolites and other 
minerals to clays. 
Name and description edited. SZ information 
merged from TSPA-SR FEP 2.2.10.06.00. 
2.2.10.13.00 Density-driven Groundwater Flow 
(thermal) 
Thermal effects in the geosphere could affect the 
long-term performance of the disposal system. 
Thermal effects are most important in waste, 
engineered barrier system, and the disturbed zone 
surrounding the excavation. 
2.2.10.13.0A Repository-induced thermal effects 
on flow in the SZ 
Thermal effects in the geosphere could affect the 
long-term performance of the disposal system, 
including effects on groundwater flow (e.g., density-
driven flow), mechanical properties, and chemical 
effects in the SZ. 
Name and description edited to be SZ specific. 
SZ information merged from TSPA-SR FEP 
2.2.10.01.00. 

2.2.11.01.00 Naturally Occurring Gases in the 
Geosphere 
Naturally occurring gases in the geosphere may 
intrude into the repository or may influence 
groundwater flow paths and releases to the 
biosphere. Potential sources for gas might be 
clathrates, microbial degradation of organic 
material or deep gases in general. 
2.2.11.01.0A Gas effects in the SZ 
Pressure variations due to gas generation may affect 
flow patterns and contaminant transport in the SZ. 
Degassing could affect flow and transport of gaseous 
contaminants. Potential gas sources include 
degradation of repository components and naturally 
occurring gases from clathrates, microbial 
degradation of organic material or deep gases in 
general. 
Name and description edited to be SZ specific. 
2.2.12.00.00 Undetected Features 
This category contains FEPs related to undetected 
features in the geosphere that can affect long-term 
performance of the disposal system. Undetected 
but important features may be present, and may 
have significant impacts. These features include 
unknown active fracture zones, inhomogeneities, 
faults and features connecting different zones of 
rock, different geometries for fracture zones, and 
induced fractures due to the construction or 
presence of the repository. 
2.2.12.00.0B Undetected features in the SZ 
This FEP is related to undetected features in the SZ 
portion of the geosphere that can affect long-term 
performance of the disposal system. Undetected but 
important features may be present, and may have 
significant impacts. These features include unknown 
active fracture zones, inhomogeneities, faults and 
features connecting different zones of rock, and 
different geometries for fracture zones. 
FEP Split into SZ and UZ. Name and description 
edited to be SZ specific. 
2.3.02.02.00 Radionuclide Accumulation in 
Soils 
Radionuclide accumulation in soils may occur as a 
result of upwelling of contaminated groundwater 
(leaching, evaporation at discharge location) or 
deposition of contaminated water or particulates 
(irrigation water, runoff, atmospheric deposition). 
Not applicable  Not assigned to SZ for LA 
This FEP is now assigned to Biosphere. 
Recycling of radionuclides is addressed in 
1.4.07.03.0A 

2.3.11.04.00 Groundwater Discharge to Surface 
Radionuclides transported in groundwater as 
solutes or solid materials (colloids) from the far field 
to the biosphere will discharge at specific entry 
points in the biosphere. Surface discharge points 
may be surface water bodies (rivers, lakes), 
wetlands, or unsaturated terrestrial soils. 
2.3.11.04.0A Groundwater discharge to surface 
outside the reference biosphere 
Radionuclides transported in groundwater as solutes 
or solid materials (colloids) from the far field may 
discharge at specific "entry" points that are outside 
the reference biosphere. Natural surface discharge 
points, including those resulting from water table or 
capillary rise, may be surface water bodies (rivers, 
lakes), springs, wetlands, holding ponds, or 
unsaturated soils. 
Name and description edited to include water 
table and capillary rise. 
3.1.01.01.00 Radioactive Decay and Ingrowth 
Radioactive decay of the fuel in the repository 
changes the radionuclide content in the fuel with 
time and generates heat. Radionuclide quantities 
in the system at any time are the result of the 
radioactive decay and the growth of daughter 
products as a consequence of that decay (i.e., 
ingrowth). The type of radiation generated by the 
decay depends on the radionuclide, and the 
penetrating distance of the radiation depends on 
the type of radiation, its energy, and the 
surrounding medium. 
3.1.01.01.0A Radioactive decay and ingrowth 
Radioactivity is the spontaneous disintegration of an 
unstable atomic nucleus that results in the emission 
of subatomic particles. Radioactive isotopes are 
known as radionuclides. Radioactive decay of the 
fuel in the repository changes the radionuclide 
content in the fuel with time and generates heat. 
Radionuclide quantities in the system at any time are 
the result of the radioactive decay and the growth of 
daughter products as a consequence of that decay 
(i.e., ingrowth). Over a 10,000-year performance 
period, these processes will produce daughter 
products that need to be considered in order to 
adequately evaluate the release and transport of 
radionuclides to the accessible environment. 
Description edited for clarity. 
3.2.07.01.00 Isotopic Dilution 
Mixing or dilution of the radioactive species from 
the waste with species of the same element from 
other sources (i.e., stable and/or naturally occurring 
isotopes of the same element) will lead to a 
reduction of the radiological consequences. 
3.2.07.01.0A Isotopic dilution 
Mixing or dilution of the radioactive species from the 
waste with species of the same element from other 
sources (i.e., stable and/or naturally occurring 
isotopes of the same element) could lead to a 
reduction of the radiological consequences. 
No change. 
a Italicized text indicates changes made subsequent to DTN: MO0307SEPFEPS4.000 [164527]. 

The second step of the FEP analysis process is the screening of potentially relevant FEPs based 
on the criteria identified in Section 4.3 of this report. A schematic of the FEP identification and 
screening process is given in Figure 1.2-1. Although shown as sequential activities, iteration 
occurs as new information becomes available that might result in new FEPs and/or changes to 
the technical bases for screening. 
Figure 1.2-1. Development and Screening Process for FEPs Related to the Saturated Zone 
Table 1.2-2 and Table 1.2-3 list all SZ included and excluded FEPs, accompanied by FEP 
descriptions. Additionally, Table 1.2-2 maps the included SZ FEPs to supporting SZ reports 
where the FEP implementation in TSPA-LA is fully documented (where the TSPA-LA 
disposition is developed). Table 1.2-2 also identifies supplemental supporting SZ reports where 
a partial treatment of the implementation of the FEP is described. For each excluded FEP, Table 
1.2-3 identifies this report as the SZ report where the FEP screening argument is fully 
documented. It also identifies supplemental supporting SZ reports that provide additional 
information about the technical basis for exclusion and are used to support exclusion of that 
particular FEP. Note that excluded FEPs are not explicitly mentioned in the supporting SZ 
reports. In some cases, a FEP covers multiple technical areas and is shared with other FEP 
analysis reports. Shared FEPs are identified in Tables 1.2-2 and 1.2-3. 

Table 1.2-2. Included Saturated Zone FEPs 
LA FEP 
Number 
FEP Name 
YMP Description 
Supporting SZ Reports Listed by Document 
Identifiers (SZ Reports Listed in Italics Only 
Partially Address the FEP) 
FEP Shared 
With 
1.2.02.01.0A
Fractures
Groundwater flow in the Yucca Mountain region and 
transport of any released radionuclides may take place 
along fractures. The rate of flow and the extent of 
transport in fractures are influenced by characteristics 
such as orientation, aperture, asperity, fracture length, 
connectivity, and the nature of any linings or in-fills. 
MDL-NBS-HS-000021 (BSC 2003 [167651], 
Section 6.2) 
MDL-NBS-HS-000010 (BSC 2003 [167208]); 
MDL-NBS-HS-000011 (BSC 2003 [166262]); 
ANL-NBS-HS-000039 (BSC 2003 [167209]) 
UZ 
1.2.02.02.0A
Faults
Numerous faults of various sizes have been noted in 
the Yucca Mountain region and in the repository area in 
specific. Faults may represent an alteration of the rock 
permeability and continuity of the rock mass, alteration 
or short-circuiting of the flow paths and flow 
distributions close to the repository, and represent 
unexpected pathways through the repository. 
MDL-NBS-HS-000021 (BSC 2003 [167651], 
Section 6.2) 
MDL-NBS-HS-000010 (BSC 2003 [167208]); 
MDL-NBS-HS-000011 (BSC 2003 [166262]; 
ANL-NBS-HS-000039 (BSC 2003 [167209]) 
UZ 
1.3.07.02.0A
Water tablerise affects SZ 
Climate change could produce increased infiltration, 
leading to a rise in the regional water table, possibly 
affecting the release and exposure pathways from the 
repository by altering flow and transport pathways in the 
SZ. A regionally higher water table and change in SZ 
flow patterns might move discharge points closer to the 
repository. 
MDL-NBS-HS-000021 (BSC 2003 [167651]) 
NOTE: This FEP was not explicitly listed as an 
included FEP in any of the supporting SZ reports. 
However, details of the implementation of the FEP 
in TSPA-LA are described in MDL-NBS-HS-
000021 (BSC 2003 [167651]). 
None 
1.4.07.01.0A
Watermanagement 
activities 
Water management is accomplished through a 
combination of dams, reservoirs, canals, pipelines, and 
collection and storage facilities. Water management 
activities could have a major influence on the behavior 
and transport of contaminants in the biosphere. 
MDL-NBS-HS-000021 (BSC 2003 [167651]) 
Biosphere 
1.4.07.02.0A 
Wells 
One or more wells drilled for human use (e.g., drinking 
water, bathing) or agricultural use (e.g., irrigation, 
animal watering) may intersect the contaminant plume. . 
MDL-NBS-HS-000021 (BSC 2003 [167651], 
Section 6.2) 
MDL-NBS-HS-000011 (BSC 2003 [166262]) 
Biosphere 

Table 1.2-2. Included Saturated Zone FEPs (Continued) 
LA FEP 
Number 
FEP Name 
YMP Description 
Supporting SZ Reports Listed by Document 
Identifiers (SZ Reports Listed in Italics Only 
Partially Address the FEP) 
FEP Shared 
With 
2.2.03.01.0A
Stratigraphy
Stratigraphic information is necessary information for 
the performance assessment. This information should 
include identification of the relevant rock units, soils, 
and alluvium, and their thickness, lateral extents, and 
relationships to each other. Major discontinuities 
should be identified. 
MDL-NBS-HS-000011 (BSC 2003 [166262], 
Section 6) 
MDL-NBS-HS-000021 (BSC 2003 [167651] 
UZ 
2.2.03.02.0A
Rockproperties of 
host rock and 
other units 
Physical properties such as porosity and permeability of 
the relevant rock units, soils, and alluvium are 
necessary for the performance assessment. Possible 
heterogeneities in these properties should be 
considered. Questions concerning events and 
processes that may cause these physical properties to 
change over time are considered in other FEPs. 
MDL-NBS-HS-000021 (BSC 2003 [167651], 
Section 6.2) 
ANL-NBS-HS-000039 (BSC 2003 [167209]); 
MDL-NBS-HS-000010 (BSC 2003 [167208]); 
MDL-NBS-HS-000011 (BSC 2003 [166262]) 
UZ 
2.2.07.12.0A
Saturatedgroundwater 
flow in the 
geosphere 
Groundwater flow in the saturated zone below the water 
table may affect long-term performance of the 
repository. The location, magnitude, and direction of 
flow under present and future conditions and the 
hydraulic properties of the rock are all relevant. 
MDL-NBS-HS-000011 (BSC 2003 [166262]), 
Section 6.2) 
ANL-NBS-HS-000021 (BSC 2003 [167211]) 
None 
2.2.07.13.0A
Water-conduct-ing features in 
the SZ 
Geologic features in the saturated zone may affect 
groundwater flow by providing preferred pathways for 
flow. 
MDL-NBS-HS-000021 (BSC 2003 [167651], 
Section 6.2) 
MDL-NBS-HS-000010 (BSC 2003 [167208]); 
MDL-NBS-HS-000011 (BSC 2003 [166262]); 
ANL-NBS-HS-000039 (BSC 2003 [167209]) 
None 
2.2.07.15.0A
Advection anddispersion in 
the SZ 
Advection and dispersion processes may affect 
contaminant transport in the SZ. 
MDL-NBS-HS-000010 (BSC 2003 [167208], 
Section 6) 
MDL-NBS-HS-000011 (BSC 2003 [166262]); 
MDL-NBS-HS-000021 (BSC 2003 [167651]); 
ANL-NBS-HS-000039 (BSC 2003 [167209]) 
None 
2.2.07.16.0A
Dilution ofradionuclides 
in groundwater 
Dilution due to mixing of contaminated and 
uncontaminated water may affect radionuclide 
concentrations in groundwater during transport in the 
saturated zone and during pumping at a withdrawal 
well. 
MDL-NBS-HS-000021 (BSC 2003 [167651], 
Section 6.2) 
MDL-NBS-HS-000010 (BSC 2003 [167208]) 
None 

Table 1.2-2. Included Saturated Zone FEPs (Continued) 
LA FEP 
Number 
FEP Name 
YMP Description 
Supporting SZ Reports Listed by 
Document Identifiers (SZ Reports Listed in 
Italics Only Partially Address the FEP) 
FEP 
Shared 
With 
2.2.07.17.0A
Diffusion in the 
SZ 
Molecular diffusion processes may affect radionuclide 
transport in the SZ. 
MDL-NBS-HS-000010 (BSC 2003 [167208], 
Section 6.2) 
MDL-NBS-HS-000021 (BSC 2003 [167651]); 
ANL-NBS-HS-000039 (BSC 2003 [167209]) 
None 
2.2.08.01.0A
Chemicalcharacteristics 
of groundwater 
in the SZ 
Chemistry and other characteristics of groundwater in 
the saturated zone may affect groundwater flow and 
radionuclide transport of dissolved and colloidal 
species. Groundwater chemistry and other 
characteristics, including temperature, pH, Eh, ionic 
strength, and major ionic concentrations, may vary 
spatially throughout the system as a result of different 
rock mineralogy. 
MDL-NBS-HS-000010 (BSC 2003 [167208], 
Section 6) 
MDL-NBS-HS-000011 (BSC 2003 [166262]); 
ANL-NBS-HS-000021 (BSC 2003 [167211]); 
MDL-NBS-HS-000021 (BSC 2003 [167651]) 
None 
2.2.08.06.0A
Complexationin the SZ 
Complexing agents such as humic and fulvic acids 
present in natural groundwaters could affect 
radionuclide transport in the SZ. 
MDL-NBS-HS-000010 (BSC 2003 [167208], 
Section 6.2) 
MDL-NBS-HS-000021 (BSC 2003 [167651]) 
None 
2.2.08.08.0A
Matrix diffusionin the SZ 
Matrix diffusion is the process by which radionuclides 
and other species transported in the SZ by advective 
flow in fractures or other pathways move into the matrix 
of the porous rock by diffusion. Matrix diffusion can be 
a very efficient retarding mechanism, especially for 
strongly sorbed radionuclides, due to the increase in 
rock surface accessible to sorption. 
MDL-NBS-HS-000010 (BSC 2003 [167208], 
Section 6.2) 
MDL-NBS-HS-000021 (BSC 2003 [167651]); 
ANL-NBS-HS-000039 (BSC 2003 [167209]) 
None 

2.2.08.09.0A 
Sorption in the 
SZ 
Sorption of dissolved and colloidal radionuclides in the 
SZ can occur on the surfaces of both fractures and 
matrix in rock or soil along the transport path. Sorption 
may be reversible or irreversible, and it may occur as a 
linear or nonlinear process. Sorption kinetics and the 
availability of sites for sorption should be considered. 
Sorption is a function of the radio-element type, mineral 
type, and groundwater composition. 
MDL-NBS-HS-000010 (BSC 2003 [167208], 
Section 6.2) 
MDL-NBS-HS-000021 (BSC 2003 [167651]) 
None 
2.2.08.10.0A
Colloidaltransport in the 
SZ 
Radionuclides may be transported in groundwater in the 
SZ as colloidal species. Types of colloids include true 
colloids, pseudo colloids, and microbial colloids. 
MDL-NBS-HS-000021 (BSC 2003 [167651], 
Section 6.2) 
MDL-NBS-HS-000010 (BSC 2003 [167208]); 
ANL-NBS-HS-000031 (BSC 2003 [162729]); 
ANL-NBS-HS-000039 (BSC 2003 [167209) 
None 
2.2.08.11.0A
Groundwaterdischarge to 
surface within 
the reference 
biosphere 
Radionuclides transported in groundwater as solutes or 
solid materials (colloids) from the far-field may 
discharge at specific "entry" points that are within the 
reference biosphere. Natural surface discharge points, 
including those resulting from water table or capillary 
rise, may be surface water bodies (rivers, lakes), 
springs, wetlands, holding ponds, or unsaturated soils. 
MDL-NBS-HS-000021 (BSC 2003 [167651], 
Section 6.2) 
Biosphere 
2.2.10.03.0A
Naturalgeothermal 
effects on flow 
in the SZ 
The existing geothermal gradient, and spatial or 
temporal variability in that gradient, may affect 
groundwater flow in the SZ. 
MDL-NBS-HS-000011 (BSC 2003 [166262], 
Section 6) 
None 

2.2.12.00.0B
Undetectedfeatures in the 
SZ 
This FEP is related to undetected features in the SZ 
portion of the geosphere that can affect long-term 
performance of the disposal system. Undetected but 
important features may be present and may have 
significant impacts. These features include unknown 
active fracture zones, inhomogeneities, faults and 
features connecting different zones of rock, and 
different geometries for fracture zones. 
MDL-NBS-HS-000021 (BSC 2003 [167651], 
Section 6.2) 
ANL-NBS-HS-000039 (BSC 2003 [167209]) 
None 
3.1.01.01.0A
Radioactivedecay and 
ingrowth 
Radioactivity is the spontaneous disintegration of an 
unstable atomic nucleus that results in the emission of 
subatomic particles. Radioactive isotopes are known 
as radionuclides. Radioactive decay of the fuel in the 
repository changes the radionuclide content in the fuel 
with time, and generates heat. Radionuclide quantities 
in the system at any time are the result of the 
radioactive decay and the growth of daughter products 
as a consequence of that decay (i.e. ingrowth). Over a 
10,000-year performance period, these processes will 
produce daughter products that need to be considered 
in order to adequately evaluate the release and 
transport of radionuclides to the accessible 
environment. 
MDL-NBS-HS-000021 (BSC 2003 [167651], 
Section 6.2) 
Biosphere, 
UZ, WF 
NOTE: Titles of the scientific analyses reports and model reports listed in this table under their document identifiers are as follows: 
MDL-NBS-HS-000021, SZ Flow and Transport Model Abstraction (BSC 2003 [167651]); MDL-NBS-HS-000010, Site-Scale Saturated Zone Transport (BSC 2003 
[167208]); MDL-NBS-HS-000011, Site-Scale Saturated Zone Flow Model (BSC 2003 [166262]); ANL-NBS-HS-000021, Geochemical and Isotopic Constraints on 
Groundwater Flow Directions and Magnitudes, Mixing, and Recharge at Yucca Mountain (BSC 2003 [167211]); ANL-NBS-HS-000031, Saturated Zone Colloid 
Transport (BSC 2003 [162729]); ANL-NBS-HS-000039, Saturated Zone In-Situ Testing (BSC 2003 [167209]). 

Table 1.2-3. Excluded Saturated Zone FEPs 
LA FEP 
Number 
FEP Name 
YMP Description 
Supporting SZ Reports Listed by Document 
Identifiers (SZ Reports Listed in Italics Only 
Partially Address the FEP) 
FEP Shared 
With 
1.2.04.02.0A
Igneousactivity 
changes rock 
properties 
Igneous activity near the underground facility causes 
extreme changes in rock stress and the thermal regime, 
and may lead to rock deformation, including activation, 
creation, and sealing of faults and fractures. This may 
cause changes in the rock hydrologic and mineralogic 
properties hydrologic and mineralogic properties. 
Permeabilities of dikes and sills and the heated regions 
immediately around them can differ from those of 
country rock. Mineral alterations can also change the 
chemical response of the host rock to contaminants. 
This report. 
DE, UZ 
1.2.04.07.0B
Ashredistribution 
in groundwater 
Following deposition of contaminated ash on the 
surface, contaminants may leach out of the ash deposit 
and be transported through the subsurface to the 
compliance point. 
This report. 
None 
1.2.06.00.0A
Hydrothermalactivity 
Naturally-occurring high-temperature groundwater may 
induce hydrothermal alteration of minerals in the rocks 
through which the high-temperature groundwater flows. 
This report. 
ANL-NBS-HS-000021 (BSC 2003 [167211]) 
UZ 
1.2.09.02.0A
Large-scaledissolution 
Dissolution can occur when any soluble mineral is 
removed by flowing water, and large-scale dissolution 
is a potentially important process in rocks that are 
composed predominantly of water-soluble evaporite 
minerals, such as salt. 
This report. 
UZ 
1.2.10.01.0A
Hydrologicresponse to 
seismic activity 
Seismic activity, associated with fault movement, may 
create new or enhanced flow pathways and/or 
connections between stratigraphic units, or it may 
change the stress (and therefore, fluid pressure) within 
the rock. These responses have the potential to 
significantly change the surface- and groundwater-flow 
directions, water level, water chemistry, and 
temperature. 
This report. 
ANL-NBS-HS-000021 (BSC 2003 [167211]); 
MDL-NBS-HS-000011 (BSC 2003 [166262]) 
DE, UZ 

Table 1.2-3. Excluded Saturated Zone FEPs (Continued) 
LA FEP 
Number 
FEP Name 
YMP Description 
Supporting SZ Reports Listed by Document 
Identifiers (SZ Reports Listed in Italics Only 
Partially Address the FEP) 
FEP Shared 
With 
1.2.10.02.0A
Hydrologicresponse to 
igneous 
activity 
Igneous activity includes magmatic intrusions, which 
may alter groundwater flow pathways, and thermal 
effects, which may heat up groundwater and rock. 
Igneous activity may change the groundwater flow 
directions, water level, water chemistry, and 
temperature. Eruptive and extrusive phases may 
change the topography, surface drainage patterns, and 
surface soil conditions. This may affect infiltration rates 
and locations. 
This report. 
DE, UZ 
1.3.07.01.0A
Water tabledecline 
Climate change could produce decreased infiltration 
(e.g., an extended drought), leading to a decline in the 
water table in the saturated zone, which would affect 
the release and exposure pathways from the repository. 
This report. 
MDL-NBS-HS-000010 (BSC 2003 [167208]); 
MDL-NBS-HS-000011 (BSC 2003 [166262]); 
MDL-NBS-HS-000021 (BSC 2003 [167651]); 
ANL-NBS-HS-000021 (BSC 2003 [167211]) 
UZ 
1.4.07.03.0A 
Recycling of 
accumulated 
radionuclides 
from soils to 
groundwater 
Radionuclides that have accumulated in soils (e.g., 
from deposition of contaminated irrigation water or 
particulates) may leach out of the soil and be recycled 
back into the groundwater as a result of recharge 
(either from natural or agriculturally induced infiltration). 
The recycled radionuclides may lead to enhanced 
radionuclide exposure at the receptor 
This report. 
None 
2.1.09.21.0B
Transport ofparticles larger 
than colloids in 
the SZ 
Particles of radionuclide-bearing material larger than 
colloids could be entrained in suspension and then be 
transported in water flowing through the SZ. 
This report. 
MDL-NBS-HS-000011 (BSC 2003 [166262]) 
MDL-NBS-HS-000021 (BSC 2003 [167651]); 
ANL-NBS-HS-000031 (BSC 2003 [162729]) 
None 
2.2.06.01.0A
Seismicactivity 
changes 
porosity and 
permeability of 
rock 
Seismic activity (fault displacement or vibratory ground 
motion) has a potential to change rock stresses and 
result in strains that affect flow properties in rock 
outside the excavation-disturbed zone. It could result in 
strains that alter the permeability in the rock matrix. 
These effects may decrease the transport times for 
potentially released radionuclides. 
This report. 
MDL-NBS-HS-000021 (BSC 2003 [167651]) 
DE, UZ 

2.2.06.02.0A
Seismicactivity 
changes 
porosity and 
permeability of 
faults 
Seismic activity (fault displacement or vibratory ground 
motion) has a potential to produce jointed-rock motion 
and change stress and strains that alter the 
permeability along faults. This could result in 
reactivation of preexisting faults or generate new faults, 
and significantly change the flow and transport paths, 
alter or short-circuit the flow paths and flow distributions 
close to the repository, and create new pathways 
through the repository. These effects may decrease 
the transport times for potentially released 
radionuclides. 
This report. 
DE, UZ 
2.2.06.02.0B
Seismicactivity 
changes 
porosity and 
permeability of 
fractures 
Seismic activity (fault displacement or vibratory ground 
motion) has a potential to change stress and strains 
that alter the permeability along fractures. This could 
result in reactivation of preexisting fractures or 
generation of new fractures. Generation of new 
fractures and reactivation of preexisting fractures may 
significantly change the flow and transport paths, alter 
or short-circuit the flow paths and flow distributions 
close to the repository, and create new pathways 
through the repository. These effects may decrease 
the transport times for potentially released 
radionuclides. 
This report. 
DE, UZ 
2.2.07.14.0A
Chemically-
induced 
density effects 
on 
groundwater 
flow 
Chemically-induced spatial variation in groundwater 
density may affect groundwater flow. 
This report. 
None 

2.2.08.03.0A
Geochemicalinteractions 
and evolution 
in the SZ 
Groundwater chemistry and other characteristics, 
including temperature, pH, Eh, ionic strength, and 
major ionic concentrations, may change through time, 
as a result of the evolution of the disposal system or 
from mixing with other waters. Geochemical 
interactions may lead to dissolution and precipitation of 
minerals along the groundwater flow path, affecting 
groundwater flow, rock properties, and sorption of 
contaminants. Effects on hydrologic flow properties of 
the rock, radionuclide solubilities, sorption processes, 
and colloidal transport are relevant. Kinetics of 
chemical reactions should be considered in the context 
of the time scale of concern. 
This report. 
MDL-NBS-HS-000010 (BSC 2003 [167208]); 
ANL-NBS-HS-000021 (BSC 2003 [167211] 
None 
2.2.08.07.0A
Radionuclidesolubility limits 
in the SZ 
Solubility limits for radionuclides may be different in 
saturated-zone groundwater than in the water in the 
unsaturated zone or in the waste and EBS. 
This report. 
MDL-NBS-HS-000021 (BSC 2003 [167651]) 
None 
2.2.09.01.0A
Microbialactivity in the 
SZ 
Microbial activity in the SZ may affect radionuclide 
mobility in rock and soil through colloidal processes, by 
influencing the availability of complexing agents, or by 
influencing groundwater chemistry. 
This report. 
MDL-NBS-HS-000010 (BSC 2003 [167208]) 
None 
2.2.10.02.0A
Thermalconvection cell 
develops in SZ 
Thermal effects due to waste emplacement result in 
convective flow in the saturated zone beneath the 
repository. 
This report. 
MDL-NBS-HS-000011 (BSC 2003 [166262]) 
None 
2.2.10.04.0A
Thermo-
mechanical 
stresses alter 
characteristics 
of fractures 
near repository 
Heat from the waste causes thermal expansion of the 
surrounding rock, generating changes in the stress field 
that may change the fracture properties (both 
hydrologic and mechanical) of fractures in the rock. 
Cooling following the peak thermal period will also 
change the stress field, further affecting fracture 
properties near the repository. 
This report. 
UZ 

2.2.10.04.0B
Thermo-
mechanical 
stresses alter 
characteristics 
of faults near 
repository 
Heat from the waste causes thermal expansion of the 
surrounding rock, generating changes to the stress field 
that may change the fault properties (both hydrologic 
and mechanical) in and along faults. Cooling following 
the peak thermal period will also change the stress 
field, further affecting fault properties near the 
repository. 
This report. 
UZ 
2.2.10.05.0A
Thermo-
mechanical 
stresses alter 
characteristics 
of rocks above 
and below the 
repository 
Thermal-mechanical compression at the repository 
produces tension-fracturing in the PTn and other units 
above the repository. These fractures alter unsaturated 
zone flow between the surface and the repository. 
Extreme fracturing may propagate to the surface, 
affecting infiltration. Thermal fracturing in rocks below 
the repository affects flow and radionuclide transport to 
the saturated zone. 
This report. 
UZ 
2.2.10.08.0A 
Thermo-
chemical 
alteration in 
the SZ 
(solubility, 
speciation, 
phase 
changes, 
precipitation/ 
dissolution) 
Thermal effects may affect radionuclide transport 
directly by causing changes in radionuclide speciation 
and solubility in the SZ, or, indirectly, by causing 
changes to host rock mineralogy that affect the flow 
path. Relevant processes include volume effects 
associated with silica phase changes, precipitation and 
dissolution of fracture filling minerals (including silica 
and calcite), and alteration of zeolites and other 
minerals to clays. 
This report. 
MDL-NBS-HS-000021 (BSC 2003 [167651]; 
MDL-NBS-HS-000010 (BSC 2003 [167208]) 
None 
2.2.10.13.0A 
Repository-
induced 
thermal effects 
on flow in the 
SZ 
Thermal effects in the geosphere could affect the long-
term performance of the disposal system, including 
effects on groundwater flow (e.g., density-driven flow), 
mechanical properties, and chemical effects in the SZ. 
This report. 
MDL-NBS-HS-000011 (BSC 2003 [166262]) 
None 

2.2.11.01.0A 
Gas effects in 
the SZ 
Pressure variations due to gas generation may affect 
flow patterns and contaminant transport in the SZ. 
Degassing could affect flow and transport of gaseous 
contaminants. Potential gas sources include 
degradation of repository components and naturally 
occurring gases from clathrates, microbial degradation 
of organic material, or deep gases in general. 
This report. 
None 
2.3.11.04.0A
Groundwaterdischarge to 
surface 
outside the 
reference 
biosphere 
Radionuclides transported in groundwater as solutes or 
solid materials (colloids) from the far-field may 
discharge at specific "entry" points that are outside the 
reference biosphere. Natural surface discharge points, 
including those resulting from water table or capillary 
rise, may be surface water bodies (rivers, lakes), 
springs, wetlands, holding ponds, or unsaturated soils. 
This report. 
Biosphere 
3.2.07.01.0A
Isotopicdilution 
Mixing or dilution of the radioactive species from the 
waste with species of the same element from other 
sources (i.e., stable and/or naturally occurring isotopes 
of the same element) could lead to a reduction of the 
radiological consequences. 
This report. 
ANL-NBS-HS-000021 (BSC 2003 [167211]) 
None 
NOTE: Titles of the scientific analyses reports and model reports listed in this table under their document identifiers are as follows: 
MDL-NBS-HS-000021, SZ Flow and Transport Model Abstraction (BSC 2003 [167651]); MDL-NBS-HS-000010, Site-Scale Saturated Zone Transport (BSC 2003 
[167208]); MDL-NBS-HS-000011, Site-Scale Saturated Zone Flow Model (BSC 2003 [166262]); ANL-NBS-HS-000021, Geochemical and Isotopic Constraints on 
Groundwater Flow Directions and Magnitudes, Mixing, and Recharge at Yucca Mountain (BSC 2003 [167211]); ANL-NBS-HS-000031, Saturated Zone Colloid 
Transport (BSC 2003 [162729]); ANL-NBS-HS-000039, Saturated Zone In-Situ Testing (BSC 2003 [167209]). 

1.2.2 Integration of SZ FEP Screening into the TSPA-LA FEP Database 
The FEP list used for the TSPA-LA screening presented in this analysis report was extracted 
from DTN: MO0307SEPFEPS4.000 [164527] and revised by SZ subject matter experts as 
documented in Table 1.2-1. In order to assist the Project during the license-review process, the 
ORD FEP team is constructing an electronic FEP database (i.e., the Yucca Mountain FEP 
database), where each FEP is entered as a separate record. Fields within each record provide 
unique FEP identification numbers, FEP descriptions, origin, FEP mapping to their assigned 
analysis and model reports, and mapping to related FEPs. Fields also provide (1) summaries of 
screening arguments for excluded FEPs, (2) TSPA dispositions for included FEPs, and (3) 
references to supporting documentation for each included and excluded FEP. 
This analysis report documents the technical bases for screening arguments and TSPA 
dispositions for the SZ FEPs that will be incorporated into the YMP TSPA-LA FEP database. 
For shared FEPs, this analysis report may provide only a partial technical basis for the screening 
of the FEP. The full technical basis for these shared FEPs is addressed collectively by all of the 
sharing FEP AMRs. 

2. QUALITY ASSURANCE 
The scientific analysis documented in this report was evaluated in accordance with AP-2.27Q, 
Planning for Science Activities [159604] and AP-SIII.9Q, Scientific Analyses [167992], and was 
determined to be quality-affecting and subject to the OCRWM Quality Assurance Requirements 
and Description (QARD) (DOE 2002 [159475]). Accordingly, efforts to develop this report 
have been conducted in accordance with the ORD quality assurance (QA) program using 
approved procedures identified in the Technical Work Plan For: Saturated Zone Flow and 
Transport Modeling and Testing, TWP-NBS-MD-000002 (BSC 2003 [166034]). Additional 
guidance has been provided in the Scientific Processes Guidelines Manual (BSC 2002 
[160313]). 
The FEPs documented herein do not themselves qualify as Q items listed on the Q-list (a list of 
structures, systems, or components that are determined to be important to safety and natural or 
engineered barriers that are determined to be important to waste isolation (Q-List, BSC 2003 
[165179], Appendix A), but have the potential to affect the performance of the natural barriers 
included on the Q-list. The report contributes to the analysis and modeling used to support 
performance assessment and provides insight into the performance of natural barriers identified 
in the Q-List as safety significance, reflecting their importance to waste isolation. The 
conclusions of this analysis report do not directly impact engineered features important to safety, 
as defined in AP-2.22Q, Classification Analyses and Maintenance of the Q-List [164786]. 

LEFT INTENTIONALLY BLANK 

3. USE OF COMPUTER SOFTWARE 
This scientific analysis report uses no computational software; therefore, this analysis is not 
subject to software controls. The analyses and arguments presented herein are based on 
guidance and regulatory requirements, results of analyses and model reports, or technical 
literature. 
This report was developed using only commercially available software, which is exempt from 
Yucca Mountain (YM) qualification procedures. Sigma Plot, Scientific Graphic Software, 
Version 3.06, Jandel Corporation, and Microsoft Excel 97 Software Release-1 are commercial 
software packages used in this analysis to display the data visually using only standard built-in 
mathematical functions. SigmaPlot is also used to plot data from the analysis. Except for simple 
built-in functions in support of simple calculations, plotting and visualization, no routines or 
macros were developed using this commercial software. The values used and displayed are 
approximate in nature and are used only to identify a range of expected values. The discussions 
in this report provide the technical basis to include or exclude a FEP. Any values or data used to 
represent included FEPs are developed in the cited reports according to their respective and 
appropriate QA procedures. 

LEFT INTENTIONALLY BLANK 

4. INPUTS 
Section 4.1 identifies all direct inputs (data, parameters, and technical information) used in this 
analysis. The status of each input is reflected on the Document Input Reference System (DIRS) 
report. Inputs have been obtained from controlled source documents and other appropriate 
sources in accordance with the controlling procedures AP-SIII.9Q, Scientific Analysis [167992], 
and AP-3.15Q Managing Technical Product Inputs [163414]. Section 4.2 addresses the FEPs 
screening criteria and relevant definitions detailed in NRCs 10 CFR 63 [156605] as identified in 
Project Requirements Document (Canori and Leitner 2003 [161770]). 
4.1 DATA AND PARAMETERS 
The inputs for included FEP TSPA dispositions are identified in Table 4.1-1 and are listed 
numerically by the DIRS number of the originating report. The inputs for excluded FEP 
screening arguments are identified in Table 4.1-2 and are also listed numerically by DIRS 
number. The nature of the FEPs screening arguments is such that cited data, parameters, and 
values are often used to derive reasoned arguments. Consequently, these cited inputs to the FEPs 
screening arguments will be affected by any anticipated cited input uncertainties of the above. 
These inputs (inclusive of conclusions drawn from analyses and model reports) are considered 
appropriate for inclusion or exclusion of SZ FEPs (i.e., FEP screening) in the development of the 
SZ Flow and Transport Model Abstraction for TSPA-LA. These direct inputs to the analysis 
developed in this report are the best relevant and qualified inputs because they are taken from the 
Yucca Mountain site and region. Justifications in using those data obtained from outside sources, 
and not considered as established fact, are also listed in Table 4.1-2. 

Table 4.1-1. Inputs for Included SZ FEPs 
Applicable Section 
FEP 
Data Name 
Originating Report 
Table 1.2-1 
All 
List of TSPA-LA FEPs 
DTN: MO0307SEPFEPS4.000 
[164527] 
Section 6.2.14 
2.2.03.01.0A 
TSPA Disposition for 
Stratigraphy 
Site-Scale Saturated Zone Flow 
Model (BSC 2003 [166262], 
Section 6.2) 
Section 6.2.19 
2.2.07.12.0A 
TSPA Disposition for 
Saturated groundwater flow in the 
geosphere 
Section 6.2.35 
2.2.10.03.0A 
TSPA Disposition for 
Natural geothermal effects on flow in 
the saturated zone 
Section 6.2.22 
2.2.07.15.0A 
TSPA Disposition for 
Advection and dispersion in the SZ 
Site-Scale Saturated Zone 
Transport (BSC 2003 [167208], 
Section 6.2) 
Section 6.2.24 
2.2.07.17.0A 
TSPA Disposition for 
Diffusion in the SZ 
Section 6.2.25 
2.2.08.01.0A 
TSPA Disposition for 
Chemical characteristics of groundwater 
in the SZ 
Section 6.2.27 
2.2.08.06.0A 
TSPA Disposition for 
Complexation in the SZ 
Section 6.2.29 
2.2.08.08.0A 
TSPA Disposition for 
Matrix diffusion in the SZ 
Section 6.2.30 
2.2.08.09.0A 
TSPA Disposition for 
Sorption in the SZ 
Section 6.2.1 
1.2.02.01.0A 
TSPA Disposition for 
Fractures 
SZ Flow and Transport Model 
Abstraction (BSC 2003 
[167651], Section 6.2) 
Section 6.2.2 
1.2.02.02.0A 
TSPA Disposition for 
Faults 
Section 6.2.10 
1.3.07.02.0A * 
(Implicit) TSPA Disposition * for 
Water table rise affects SZ 
Section 6.2.11 
1.4.07.01.0A 
TSPA Disposition for 
Water management activities 
Section 6.2.12 
1.4.07.02.0A 
TSPA Disposition for 
Wells 
Section 6.2.15 
2.2.03.02.0A 
TSPA Disposition for 
Rock properties of host rock and other 
units 
Section 6.2.20 
2.2.07.13.0A 
TSPA Disposition for 
Water-conducting features in the SZ 
Section 6.2.23 
2.2.07.16.0A 
TSPA Disposition for 
Dilution of radionuclides in groundwater 
Section 6.2.31 
2.2.08.10.0A 
TSPA Disposition for 
Colloidal transport in the SZ 
Section 6.2.32 
2.2.08.11.0A 
TSPA Disposition for 
Groundwater discharge to surface 
within the reference biosphere 
Section 6.2.42 
2.2.12.00.0B 
TSPA Disposition for 
Undetected features in the saturated 
zone 
Section 6.2.44 
3.1.01.01.0A 
TSPA Disposition for 
Radioactive decay and ingrowth 
* = This FEP was not explicitly listed as an included FEP in any of the supporting SZ reports. However, details of the 
implementation of the FEP in TSPA-LA are described in BSC 2003 [167651], Section 6.5). 

Table 4.1-2. Input for Excluded SZ FEPs 
Where Used 
FEP Number 
Data Name 
Used From 
Originating Report 
Section 6.2.9 
1.3.07.01.0A 
1) Past climate fluctuations are cyclical and 
are propagated through the UZ to SZ. 2) 
Calcite crystal formation is a function of the 
degree of saturation. 3) Evidence of past water 
table elevations is seen in crystal morphology 
and growth in Browns Room. 4) Crystal 
morphology in Browns Room indicates that the 
water table dropped by at least 6 m between 
53,000 and 92,000 years ago. 5) The current 
climate represents an extremely arid condition. 
Entire and Figure 6 
"Paleoclimatic Inferences from a 120,000-Yr 
Calcite Record of Water-Table Fluctuation in 
Browns Room of Devils Hole, Nevada." 
Quaternary Research (Szabo, B.J.; Kolesar, 
P.T.; Riggs, A.C.; Winograd, I.J.; and 
Ludwig, K.R. 1994. [100088]) 
Intended Use Justification: 1) Authors considered as experts in the field of paleo-climatology. 2) Journal publication that, as a prerequisite for publication, has 
gone through rigorous peer review. 3) Information in this article widely used in other Yucca Mountain documents. 
Section 6.2.4 
1.2.04.07.0B 
Equation for radioactive decay. 
Chapter 14, Equation 
14.11 
Physical and Chemical Hydrogeology 
(Domenico, P.A. and Schwartz, F.W. 1990 
[100569]) 
Sections 6.2.4, 
6.2.6 
1.2.04.07.0B, 
1.2.09.02.0A 
1) Carbonate and halite solubilities; 2) volcanic 
rocks tend to weather to clay minerals with a 
relatively small amount of silica going into 
solution; 3) equation for retardation factor. 
Pages 106, 404 
Groundwater (Freeze, R.A. and Cherry, 
J.A. 1979 [101173]) 
Sections 6.2.7, 
6.2.16, 6.2.17, 
6.2.18 
1.2.10.01.0A, 
2.2.06.01.0A, 
2.2.06.02.0A, 
2.2.06.02.0B 
Probability and degree of displacement for the 
Solitario Canyon Fault. 
Figure 8-3 
Probabilistic Seismic Hazard Analyses for 
Fault Displacement and Vibratory Ground 
Motion at Yucca Mountain, Nevada 
(CRWMS M&O 1998 [103731]) 
Section 6.2.16 
2.2.06.01.0A 
Probability and degree of displacement for the 
Bow Ridge Fault. 
Figure 8-2 
Section 6.2.16 
2.2.06.01.0A 
Nine regional and fault hazard displacement 
zones within the YM region. 
Figure 4-9 
Sections 6.2.7, 
6.2.16, 6.2.17, 
6.2.18 
1.2.10.01.0A, 
2.2.06.01.0A, 
2.2.06.02.0A, 
2.2.06.02.0B 
A projected 2 to 4 m mean fault displacement 
for majority of faults in Yucca Mountain Project 
(YMP) vicinity at a 1E-8 annual exceedance 
probability. 
Section 8.2 
Sections 6.2.7, 
6.2.16, 6.2.18 
1.2.10.01.0A, 
2.2.06.01.0A, 
2.2.06.02.0B 
Mean displacement in host rock is less than 
0.1 cm for a 1E-08 annual exceedance 
probability between Solitario Canyon and the 
Ghost Dance Faults and within the repository's 
elevation. 
Section 8 
Intended Use Justification: 1) Authors considered as experts in the field of seismology. 2) This is an expert elicitation document. 3) Information in this article 
widely used in other Yucca Mountain documents. 

Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
Where Used 
FEP Number 
Data Name 
Used From 
Originating Report 
Sections 6.2.7, 
6.2.16, 6.2.17 
1.2.10.01.0A, 
2.2.06.01.0A, 
2.2.06.02.0A 
1) Predicted rise in water table given future 
seismic events. 2) Numerical results using a 
seismic dislocation model indicate the 
maximum rise in the water table would be 
approximately 10 m. 3) Results from the 
regional stress model approach indicated a 
maximum water table rise of 50 m. 4) 
Predicted seismic events within the YM region 
over the next 10,000 years will not alter the 
large and globally extensive stresses imposed 
in the rock and in effect over the past 10-15 
million years. 
Chapter 5 
Ground Water at Yucca Mountain, How High 
Can It Rise? Final Report of the Panel on 
Coupled Hydrologic/Tectonic /Hydrothermal 
Systems at Yucca Mountain (National 
Research Council. 1992. [105162]) * 
Located within DTN: 
MO0310INPDEFEP.000 [165880] 
Intended Use Justification: 1) Council consists of experts in their respective geoscience fields. 2) Information in this article widely used in other Yucca 
Mountain documents. 
Sections 6.2.3, 
6.2.5, 6.2.8 
1.2.04.02.0A, 
1.2.02.02.0A, 
1.2.06.00.0A 
Grants Ridge and Paiute Ridge igneous 
activity produced only localized changes in 
rock mineralogy. 
Section 5, pages 57 and 
74 
Synthesis of Volcanism Studies for the 
Yucca Mountain Site Characterization 
Project (CRWMS M&O 1998 [105347]) * 
*Located within DTN: 
MO0310INPDEFEP.000 [165880] 
Section 6.2.8 
1.2.10.02.0A 
An intruding dike chemically and 
mineralogically alters the parent rock within a 
few meters to a few tens of meters within the 
intruding dike parent rock interface. 
Section 5, pages 1-2 
Section 6.2.8 
1.2.10.02.0A 
Paiute Ridge intrusive/extrusive center that 
formed during a brief magmatic pulse 
representing a single volcanic event. 
Entire 
"Paleomagnetic Record of a Geomagnetic 
Field Reversal from Late Miocene Mafic 
Intrusions, Southern Nevada." Science 
(Ratcliff, C.D.; Geissman, J.W.; Perry, F.V.; 
Crowe, B.M.; and Zeitler, P.K. 1994 
[106634]) 
Intended Use Justification: 1) Journal publication that, as a prerequisite for publication, has gone through rigorous peer review. 2) Information in this 
publication widely used in other Yucca Mountain documents. 
Section 6.2.13 
2.1.09.21.0B 
Viscosity of water value. 
Page 715 
Data Book on the Viscosity of Liquids 
(Viswanath, D.S. and Natarajan, G. 1989 
[129867]) 
Section 6.2.13 
2.1.09.21.0B 
Density of water value. 
Page 534 
Fluid Mechanics (Streeter, V.L. and Wylie, 
E.B. 1979 [145287]) 

Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
Where Used 
FEP Number 
Data Name 
Used From 
Originating Report 
Sections 6.2.33, 
6.2.41 
2.2.09.01.0A 
2.2.11.01.0A 
Organic carbon levels in YM wells. 
Table S01053003 
Field, Chemical and Isotopic Data from 
Wells in Yucca Mountain Area, Nye County, 
Nevada, Collected Between 12/11/98 and 
11/15/99. DTN: GS010308312322.003 
[154734] (Table S01053003) 
Sections 6.2.4, 
6.2.21 
1.2.04.07.0B, 
2.2.07.14.0A 
Expected volume of groundwater is to be used 
in determining RN concentration in 
contaminant plume equals 3,000 acre-feet per 
year. 
63.332 
10 CFR 63. Energy: Disposal of High-Level 
Radioactive Wastes in a Geologic 
Repository at Yucca Mountain, 
Nevada [156605] 
Section 6.2.26 
2.2.08.03.0A 
Regulations dictate present socio-economic 
practices are reflective of future practices. 
63.305 
Sections 6.2.43, 
6.2.46 
2.3.11.04.0A 
Reference biosphere in which the RMEI will 
reside; RMEI lives above the highest 
concentration of RN in plume. 
63.2, 63.312 
Intended Use Justification: Volume of water to be used to determine RN concentrations, definitions, and projected societal futures considered in the analysis 
are specified in the above NRC regulation. 
Sections 6.2.3, 
6.2.5, 6.2.8 
1.2.04.02.0A, 
1.2.02.02.0A, 
1.2.06.00.0A 
Paiute Ridge investigations suggest igneous 
activities altered rock properties within only a 
few tens of centimeters out from the rock/dike 
interface and at most a meter perpendicular to 
the intruding dike. 
Pages 7 and 8 
Structural Control on Basaltic Dike and Sill 
Emplacement, Paiute Ridge Mafic Intrusion 
Complex, Southern Nevada (Carter Krogh, 
K.E. and Valentine, G.A. 1996 [160928]) * 
Located within DTN: 
MO0310INPDEFEP.000 [165880] 
Section 6.2.8 
1.2.10.02.0A 
Paiute Ridge investigation suggests that dike 
location and orientation was influenced by the 
orientation of the local stress field and the 
presence of existing faults. 
Pages 7 and 8 
Intended Use Justification: 1) Authors considered as experts in the field of volcanology. 2) Information in this article widely used in other Yucca Mountain 
documents. 
Section 6.2.4 
1.2.04.07.0B 
Number of waste packages brought to the 
surface by a single volcanic eruption 
intersecting one drift. 
Attachment A 
Number of Waste Packages Hit by Igneous 
Intrusion (BSC 2003 [161851]) 
Section 6.2.4 
1.2.04.07.0B 
Grams and activity of radionuclides per CSNF 
waste package - nominal case.. 
Table 21, 
Attachment III 
Initial Radionuclide Inventories. (BSC 2003 
[161961]) 
Section 6.2.13 
2.1.09.21.0B 
Colloid filtering and settling observed in lab 
and field tests. 
Sections 6.4.2 and 6.5 
Saturated Zone Colloid Transport (BSC 
2003 [162729]) 

Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
Where Used 
FEP Number 
Data Name 
Used From 
Originating Report 
Section 6.2.4 
1.2.04.07.0B 
Approximate UZ thickness in region near 
hypothetical pumping well. 
Borehole data 
GS010908312332.002. Borehole Data from 
Water-Level Data Analysis for the Saturated 
Zone Site-Scale Flow and Transport Model. 
Submittal date: 10/02/2001. [163555] 
Sections 6.2.3, 
6.2.5 
1.2.04.02.0A 
1.2.06.00.0A 
Igneous activity within the Yucca Mountain 
region is now in a relatively quiescent phase. 
Section 6.2 
Characterize Framework for Igneous Activity 
at Yucca Mountain, Nevada (BSC 2003 
[163769]) 
Section 6.2.4 
1.2.04.07.0B 
Probability of a dike intersecting the repository 
footprint1.7 E-08/year; probability of volcanic 
eruption within the repository footprint, 
conditional on dike intersection1.3 E-08/year; 
probability of such an eruptive event within 
10,000 years, when dose rate is potentially 
significant1.3 E-04/year. 
Sections 7.1, 7.2 
Section 6.2.5 
1.2.06.00.0A 
Past hydrothermal areas (Calico Hills, Claim 
Canyon, and along the south flank of 
Shoshone Mountain) are not along the SZ flow 
path and lie north and northeast of Yucca 
Mountain; future igneous activity within the 
Crater Flat basin will typically cause minimal, 
highly localized basaltic dike-like intrusions. 
Figure 3, Sections 
6.3.2, 6.4.2 
Section 6.2.4 
1.2.04.07.0B 
BCDFs for selected radionuclides. 
Table 6.2-5 
Nominal Performance Biosphere Dose 
Conversion Factor Analysis (BSC 2003 
[164403]) 
Table 1.2-1 
All 
List of TSPA-LA FEPs. 
Entire 
DTN: MO0307SEPFEPS4.000 [164527] 
Section 6.2.4 
1.2.04.07.0B 
Estimated recharge flux rates in upper Jackass 
Flats is 2.21 mm/year. 
Table 6.1.3-1 
Recharge and Lateral Groundwater Flow 
Boundary Conditions for the Saturated Zone 
Site-Scale Flow and Transport Model (BSC 
2001[164648]) 

Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
Where Used 
FEP Number 
Data Name 
Used From 
Originating Report 
Section 6.2.13 
2.1.09.21.0B 
RN bearing particles larger than colloids are 
not introduced from the UZ to the SZ. 
Section 6.3.4 
Features, Events, and Processes in UZ Flow 
and Transport (BSC 2003 [164873]) 
Section 6.2.34 
2.2.10.02.0A 
Thermal effects have an insignificant impact 
on flow in the UZ. 
Section 6.8.9 
Sections 6.2.36, 
6.2.38, 6.2.39 
2.2.10.04.0A, 
2.2.10.05.0A, 
2.2.10.08.0A 
Repository induced thermo-mechanical 
stresses on fractures, rock properties, and 
repository induced thermal-chemical effects on 
dissolution and precipitation are excluded in 
the UZ (near field). 
Sections 6.8.12, 6.8.14 
Section 6.2.37 
2.2.10.04.0B 
Effects of thermal loading on faults are 
excluded in the near field. 
Section 6.8.11 
Section 6.2.4 
1.2.04.07.0B 
Average volumetric moisture content for 
Amargosa Desert native soil. 
Entire and Figure 16 
Selected Micrometerological and Soil-
Moisture Data at Amargosa Desert 
Research Site in Nye County Near Beatty, 
Nevada, (Johnson, Michael J., Charles J. 
Mayers, and Brian J. Andraski 2002 
[165069]) 
Intended Use Justification: 1) USGS soil moisture data taken from site specific location. 2) Publication, that as a prerequisite for release, has gone through 
USGS review. 
Section 6.2.6 
1.2.09.02.0A 
Along the predicted SZ transport path the 
depth of carbonate aquifer is over 1,000 m 
below the current water table. 
Figures 6-2 and 6-18 
Errata, Hydrogeologic Framework Model for 
the Saturated-Zone Site-Scale Flow and 
Transport Model (USGS 2003 [165176]) 

Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
Where Used 
FEP Number 
Data Name 
Used From 
Originating Report 
Section 6.2.6 
1.2.09.02.0A 
The transport pathways in the SZ are primarily 
through volcanic tuffs and alluvial material. 
Section 6.6.2.3 
Site-Scale Saturated Zone Flow Model 
(BSC 2003 [166262]) 
Section 6.2.7 
1.2.10.01.0A 
Calibration process includes (1) spatially 
varying multiple flow and transport parameters 
such as permeability, porosity, anisotropy, 
faults and fault zones, and the orientation and 
nature of faults to measured and interpolated 
water levels, and (2) sensitivity of the 
calibrated parameters to grid size and grid 
resolution. 
Sections 6.5.3.2, 6.6.1, 
and 7.0 
Section 6.2.9 
1.3.07.01.0A 
Collective thickness of SZ units where most of 
flow and transport takes place is 300 m. 
Section 6.5.3.3 
Sections 6.2.9, 
6.2.13 
1.3.07.01.0A, 
2.1.09.21.0B 
Saturated zone base case flow calculations 
show transport path under current and wetter 
climate conditions is mainly in the following 
units: Prow Pass, Bullfrog, and Tram subunits 
of Crate Flat Formation, Upper Volcanic 
Confining Unit, Upper Volcanic Aquifer, 
Undifferentiated Valley Fill and Alluvium. 
Sections 6.6.2.2, 6.6.2.3 
Section 6.2.13 
2.1.09.21.0B 
Permeability of the confining unit between the 
Carbonate aquifer and the Bullfrog unit is 
10E-15 m2. 
Figure 37 
Section 6.2.13 
2.1.09.21.0B 
The temperature range for Yucca Mountain SZ 
waters is approximately 20 to 55C, with the 
majority of temperatures within the upper 20 to 
lower 30C. 
Section 7.4 
Section 6.2.13 
2.1.09.21.0B 
Carbonate Aquifer hydraulic head 
measurements is 752.4 m at well UE-25p#1 
and 730.2 m in shallower units at 
approximately the same location (wells UE-
25c#1, UE-25c#2, UE-25c#3). 
Table 13 
Section 6.2.13 
2.1.09.21.0B 
Mean permeability value for the alluvium is 
2E-13 m2. 
Table 23 

Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
Where Used 
FEP Number 
Data Name 
Used From 
Originating Report 
Section 6.2.13 
2.1.09.21.0B 
On a regional scale, fracture permeability in 
the Bullfrog, Tram and Prow Pass units ranges 
over 3 orders of magnitude. 
Section 6.6.1.4 
Site-Scale Saturated Zone Flow Model 
(BSC 2003 [166262]) (continued) 
Section 6.2.16 
2.2.06.01.0A 
1) The Bow Ridge Fault is one of many faults 
incorporated in the Imbricate Zone. 
2) Hydrological properties and dimensions of 
the Imbricate Zone. 
Section 6.5.3.4 and 
Table 12 
Section 6.2.16 
2.2.06.01.0A 
The Imbricate Zone has relatively lower 
anisotropy ratios than other volcanic regions in 
the SZ flow domain. 
Section 6.4.3.2 and 
Figure 7 
Section 6.2.17 
2.2.06.02.0A 
Solitario Canyon fault is a groundwater divide 
between the Yucca Mountain and Crater Flat 
regions. 
Section 6.3.2 
Section 6.2.26 
2.2.08.03.0A 
1) SZ flow primarily takes place in the Prow 
Pass and Bullfrog units; 2) characteristics of 
flow in Prow Pass and Bullfrog units. 
Section 6.2.4.4 
Sections 6.2.34, 
6.2.40 
2.2.10.02.0A, 
2.2.10.13.0A 
There are locations along the SZ transport 
path where ambient temperatures increase 
with depth, with some temperatures as high as 
40 to 45C. 
Table 28 
Sections 6.2.34, 
6.2.36, 6.2.37, 
6.2.38, 6.2.39, 
6.2.40 
2.2.10.02.0A, 
2.2.10.04.0A, 
2.2.10.04.0B, 
2.2.10.05.0A, 
2.2.10.08.0A, 
2.2.10.13.0A 
Description of model used to evaluate 
mountain-scale effects of thermal loading on 
host rock due to waste emplacement. 
Section 6.5 
Mountain-Scale Coupled Processes 
(TH/THC/THM) (BSC 2003 [166498]) 
Sections 6.2.34, 
6.2.39, 6.2.40 
2.2.10.02.0A, 
2.2.10.08.0A, 
2.2.10.13.0A 
Thermal loading on host rock due to waste 
emplacement causes host rock to reach a 
peak temperature of 103oC around 1000 years 
after waste emplacement. 
Section 6.5.10 

Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
Where Used 
FEP Number 
Data Name 
Used From 
Originating Report 
Sections 6.2.34, 
6.2.39, 6.2.40 
2.2.10.02.0A, 
2.2.10.08.0A, 
2.2.10.13.0A 
1) The thermal pulse due to waste 
emplacement causes water table temperatures 
to peak around 2,000 years. 2) Temperatures 
at the water table below the repository footprint 
vary locally between at 32 to 34C. 3) Beneath 
the repository, temperatures at the water table 
decrease to within 1 to 2C of ambient levels 
at about 5,000 years after waste 
emplacement. 
Section 6.3.1 and 
Figures 6.3.1-6, 6.3.1-7 
Mountain-Scale Coupled Processes 
(TH/THC/THM) (BSC 2003 [166498]) 
(continued) 
Section 6.2.36 
2.2.10.04.0A 
At 10,000 years, thermal-mechanical stresses 
do not impart significant changes on vertical 
fracture permeabilities beyond 50 m below the 
repository. 
Figure 6.5.12-2 
Sections 6.2.36, 
6.2.37 
2.2.10.04.0A, 
2.2.10.04.0B 
1) Thermally induced stresses due to waste 
emplacement impart compressive stresses in 
fractures below the repository. 2) Thermally 
induced stresses due to waste emplacement 
impart a combination of compressive and 
tensile stresses above the repository. 
Sections 6.5.10, 6.5.11 
Sections 6.2.36, 
6.2.38 
2.2.10.04.0A, 
2.2.10.05.0A 
Model results: 1) Thermally induced 
mechanical stresses primarily affect vertical 
fractures residing between 150 m above and 
70 m below the repository and approximately 
100 m lateral to the repository plane; 2) 
Horizontal fractures located between 140 m 
above and 50 m below the repository are 
affected by thermal-mechanical stresses, but 
to a significantly lesser extent; 3) There are 
little to no changes in the permeabilities of 
both vertical and horizontal fractures located 
approximately 150 m below the repository. 
Figures 6.5.12-1, 
6.5.12-2, 6.5.12-3 
Sections 6.2.36, 
6.2.37, 6.2.38 
2.2.10.04.0A, 
2.2.10.04.0B, 
2.2.10.05.0A 
Results indicate the highest thermally induced 
stresses occur at approximately 100 years 
within the repository horizon, are horizontal in 
direction, and are compressive in nature below 
the repository; moving away from the 
repository, stresses dampen. 
Section 6.5.11 

Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
Where Used 
FEP Number 
Data Name 
Used From 
Originating Report 
Sections 6.2.36, 
6.2.37 
2.2.10.04.0A, 
2.2.10.04.0B 
Above the repository thermally induced 
stresses are a combination of compressive 
and tensile in nature. Compressive stresses 
transition to tensile stresses at approximately 
180 m above the repository. Changes from 
compressive to tensile stresses are not seen 
below the repository. 
Sections 6.5.10 and 
6.5.11 
Mountain-Scale Coupled Processes 
(TH/THC/THM) (BSC 2003 [166498]) 
(Continued) 
Sections 6.2.36, 
6.2.38 
2.2.10.04.0A, 
2.2.10.05.0A 
A reduction in vertically aligned fracture 
apertures reduces fracture permeability. 
Section 6.5.12 
Section 6.2.39 
2.2.10.08.0A 
Modeling results indicate CO2 concentrations 
just above the water table do not vary 
significantly during the modeled time period. 
Figures 6.4-12 and 6.4-
16 
Section 6.2.39 
2.2.10.08.0A 
Alteration of silicate bearing minerals 
decreases with distance from the repository. 
Minimal-to-no mineral alteration is seen just 
above the water table. Concurrently, no 
noticeable precipitation or dissolution of calcite 
bearing minerals in fracture fillings is seen. 
Section 6.4.3.3 and 
Figures 6.4-20 through 
6.4-24 
Sections 6.2.39, 
6.2.40 
2.2.10.08.0A, 
2.2.10.13.0A 
Model results show pH concentrations above 
the water table vary between 8.14 and 8.45. 
Variations in pH just above the water table are 
not accompanied with noticeable precipitation 
or dissolution of minerals such as calcite in 
fracture fillings. 
Section 6.4.3.3.1, 
Figures 6.4-12 and 6.4-
13; Section 6.4.3.3.2 
and Figures 6.4-16 and 
6.4-17; Section 
6.4.3.3.3 Figure 6.4-18 
Section 6.2.13 
2.1.09.21.0B 
Colloid particle density (Pd) values. 
Sections 5.10 and 6.3.1 
Waste Form and In-Drift Colloids-Associated 
Radionuclide Concentrations: Abstraction 
and Summary (BSC 2003 [166845]) 

Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
Where Used 
FEP Number 
Data Name 
Used From 
Originating Report 
Section 6.2.26 
2.2.08.03.0A 
Model assumes that the SZ groundwaters 
along the transport path are oxidizing from the 
UZ/SZ interface to the 18-km compliance 
boundary. 
Section 6.3 
Site-Scale Saturated Zone Transport (BSC 
2003 [167208]) 
Section 6.2.33 
2.2.09.01.0A 
The range of groundwater compositions in the 
SZ are represented by water taken from wells 
UE-25p#1 and J-13 used to derive Kd 
distributions. 
Attachment I 
Section 6.2.39 
2.2.10.08.0A 
In the model, no credit is being taken for 
sorption onto zeolites that reside along the SZ 
flow path. 
Table 6.4-1 
Section 6.2.5 
1.2.06.00.0A 
Evidence of past hydrothermal mineral 
alteration seen in Calico Hills, Claim Canyon, 
and along the south flank of Shoshone 
Figure 3 
Geochemical and Isotopic Constraints on 
Groundwater Flow Directions and 
Magnitudes, Mixing, and Recharge at Yucca 
Mountain (BSC 2003 [167211]) 
Section 6.2.7 
1.2.10.01.0A 
Geochemical modeled flow patterns and 
deduced mixing zones of paleoclimate waters 
Section 7.1.4 
Sections 6.2.7, 
6.2.26, 6.2.33 
1.2.10.01.0A, 
2.2.08.03.0A, 
2.2.09.01.0A 
Geochemical analysis indicates the current SZ 
groundwater under the repository and along 
the SZ transport path is paleoclimate recharge 
water. 
Section 7.1.2 
Section 6.2.9 
1.3.07.01.0A 
Geochemical and isotopic analyses indicate 
SZ groundwater along the projected flow path 
is between 10,000 to 16,000 years old, and its 
composition reflects recharge that occurred up 
until the late Pleistocene. 
Section 7.1 
Sections 6.2.26, 
6.2.33 
2.2.08.03.0A, 
2.2.09.01.0A 
Paleoclimate recharge waters are reflective of 
cooler climatic conditions and cooler recharge 
waters 10,000 to 16,000 years old. 
Section 6.3 
Section 6.2.45 
3.2.07.01.0A 
Examples of naturally occurring isotopes within 
the SZ flow domain (84S, 86S, 87S, 88S, 
234U, 238U, 12C, 13C). 
Section 6.7.1.2 

Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
Where Used 
FEP Number 
Data Name 
Used From 
Originating Report 
Sections 6.2.3, 
6.2.7, 6.2.16, 
6.2.17, 6.2.18 
1.2.04.02.0A, 
1.2.10.01.0A 
2.2.06.01.0A, 
Evaluation of uncertainties in flowing interval 
properties. 
Section 6.3, Table 6-8, 
Figure 6-6 
SZ Flow and Transport Model Abstraction 
(BSC 2003 [167651]) 
Section 6.2.4 
1.2.04.07.0B 
Values for, Kd, bulk density, sorption, porosity, 
and retardation factor. 
Table 6-8 
Section 6.2.4 
1.2.04.07.0B 
800-year SZ transport time starting below the 
repository footprint to compliance boundary. 
Figure 6-28 
Section 6.2.9 
1.2.04.07.0B 
Uncertainty in the volcanic-alluvium contact 
zone is modeled in the SZ. 
Section 6.5.2.2 
Section 6.2.13 
2.1.09.21.0B 
In the alluvium mean effective porosity is 0.18. 
Table 6-8 
Section 6.2.13 
2.1.09.21.0B 
Effective porosity in SZ volcanic units is 0.01. 
Section 6.5.2 
Sections 6.2.28, 
6.2.39 
2.2.08.07.0A, 
2.2.10.08.0A 
A solubility limit for each radionuclide is not 
implemented in the SZ. 
Entire 
Section 6.2.33 
2.2.09.01.0A 
RN bearing SZ colloids natural inorganic 
ligands and inorganic constituents generated 
by the degradation of emplaced waste. 
Sections 6.5.2.11 and 
6.5.2.12 
Section 6.2.7 
1.2.10.01.0A 
Tectonic activity in the Yucca Mountain region 
is in a waning phase with the focal point 
moving westward. 
Section 6.2.1.1 
Errata for Features, Events, and 
Processes: Disruptive Events 
(BSC 2004 [167720]) 
Section 6.2.16 
2.2.06.01.0A 
Zone of alteration in rock can extend a few 
meters to tens of meters due to fault 
displacement. 
Section 6.2.1.10 

Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
Where Used 
FEP Number 
Data Name 
Used From 
Originating Report 
Section 6.2.17 
2.2.06.02.0A 
A seismically induced change in rock 
properties adjacent to a fault (which implicitly 
affects the rocks hydrologic properties) will 
tend to occur in a relatively narrow zone and 
be on the order of a few meters to, at most, 
tens of meters wide. 
Section 6.2.1.10 
Errata for Features, Events, and 
Processes: Disruptive Events 
(BSC 2004 [167720]) 
(Continued) 
Sections 6.2.17, 
6.2.18 
2.2.06.02.0A, 
2.2.06.02.0B 
Energy produced from a seismic event will be 
dissipated along existing faults. 
Section 6.2.1.10 
Sections 6.2.16, 
6.2.17, 6.2.18 
2.2.06.01.0A, 
2.2.06.02.0A 
2.2.06.02.0B 
Solitario Canyon Faults cumulative 
displacement is approximately 260 m where it 
intersects the ECRB Cross-drift; with this 
relatively large displacement, its zone of 
alteration consists of approximately a 20-m 
brecciated and gouge zone and seismically 
induced fractured area that extends tens of 
meters from the fault. 
Section 6.2.1.10 
Section 6.2.46 
1.4.07.03.0A 
Regulatory basis that determines where 
RMEIs well is to be located and where RMEI 
resides. 
Entire 
Adoption of Licensing Position - Paper - LP-
028 DRAFT REV0F -Recycling of 
Radionuclides at the Location of the 
Reasonably Maximally Exposed Individual in 
the Screening Argument for the SZ FEP 
1.4.07.03.0A (Recycling of Accumulated 
Radionuclides from Soils to Groundwater) 
(Economy 2004 [167914]) 
Intended Use Justification: 1) Position based on NRC requirements. 2) Interpretation of regulatory based position developed by Regulatory Coordination 
Group. 
Section 6.2.9 
1.3.07.01.0A 
Prediction of a cooler and wetter glacial 
transition climatic condition will follow the brief 
monsoonal period and will persist for about 
8,500 years 
Section 7 
Eratta for Future Climate Analysis (USGS 
2003 [167961]) 
Section 6.2.13 
2.1.09.21.0B 
The difference between the alluvium head 
measurement at NC-EWDP 19D and NC-
EWDP 19P is 5.3 m, the elevation difference 
between these 2 wells is 293 m. 
Table 6-1 
Water-Level Data Analysis for the Saturated 
Zone Site-Scale Flow and Transport Mode, , 
with 001 Errata 001 002. (USGS 2004 
[168473]) 

Citations marked with an * were classified as TBV in the Errata for Features, Events, and 
Processes: Disruptive Events (BSC 2004 [167720], Section 4.1.1), as part of DTN 
MO0310INPDEFEP.000 [DIRS 165880] per the governing procedure. In accordance with AP-
3.15Q, data that need to be verified comprise factual information comprising site 
characterization samples and values that were collected prior to QA program implementation or 
collected by other entities that do not or did not have an approved QA program. If the data 
cannot be verified it will be qualified or replaced as part of the data confirmation process. 
Table 4.1-3. Other Regulations Used in This FEP AMR 
Where Used 
Data Name 
Originating Report 
Section 4.3.1 
Low probability criterion. 
10 CFR 63. Energy: Disposal of High-Level 
Radioactive Wastes in a Geologic Repository at 
Yucca Mountain, Nevada. [156605] (63.312, 
63.102, 63.114, 6.3.342, 63.305, 63.302, 63.2, 
entire) 
Section 4.3.2 
Low consequence criteria. 
Section 4.3.3.1 
Reference biosphere and geologic 
setting. 
Section 4.3.3.2 
Characteristics of the RMEI to be used 
in exposure calculations, distance from 
the repository to the receptor 
Section 5.3 
Justification for assumption that 
potential and naturally occurring 
geologic and climatic events (but 
perhaps not necessarily the magnitude) 
have occurred at least once in the past 
within the geologic record used as the 
basis for the TSPA. 
Section 1 
Definition of performance assessment, 
provisions followed, FEPS analysis 
issued to follow provisions 
Section 1 
Criteria specified in regulations. 

4.2 CRITERIA 
4.2.1 Acceptance Criterion for FEP Identification 
The NRC provides guidance in the Yucca Mountain Review Plan, Final Report (NRC 2003 
[163274], Section 2.2.1.2.1.3) on the screening process to exclude FEPs as follows: 
Acceptance Criterion 1: The Identification of an Initial List of Features, 
Events, and Processes is Adequate 
The Safety Analysis Report contains a complete list of features, events, and 
processes, related to the geologic setting or the degradation, deterioration, or 
alteration of engineered barriers (including those processes that would affect the 
performance of natural barriers), that have the potential to influence repository 
performance. The list is consistent with the site characterization data. Moreover, 
the comprehensive features, events, and processes list includes, but is not limited 
to, potentially disruptive events related to igneous activity (extrusive and 
intrusive); seismic shaking (high-frequency-low magnitude, and rare 
large-magnitude events); tectonic evolution (slip on existing faults and formation 
of new faults); climatic change (change to pluvial conditions); and criticality. 
How Addressed 
FEPs related to the SZ flow and transport processes evaluated in this report are listed in Section 
1, Tables 1.2-2 and 1.2-3, of this report. Identified on the two tables are those SZ Analysis 
Model Reports (AMRs) that provide supporting technical discussions relevant to a specific FEP. 
Documentation of the evolution of the YMP FEP list is provided in Section 1.2.1. 
4.2.2 Acceptance Criterion for FEP Screening 
The NRC (2003 [163274], Section 2.2.1.2.1.3) stipulates Acceptance Criterion 2 to be: 
Acceptance Criterion 2: Screening of the Initial List of Features, Events, 
and Processes Is Appropriate 
The U.S. Department of Energy has identified all features, events, and processes 
related to either the geologic setting or to the degradation, deterioration, or 
alteration of engineered barriers (including those processes that would affect the 
performance of natural barriers) that have been excluded; 
The U.S. Department of Energy has provided justification for those features, 
events, and processes that have been excluded. An acceptable justification for 
excluding features, events, and processes is that either the feature, event, and 
process is specifically excluded by regulation; probability of the feature, event, 
and process (generally an event) falls below the regulatory criterion; or omission 
of the feature, event, and process does not significantly change the magnitude and 

time of the resulting radiological exposures to the reasonably maximally exposed 
individual, or radionuclide releases to the accessible environment; and 
The U.S. Department of Energy has provided an adequate technical basis for each 
feature, event, and process, excluded from the performance assessment, to support 
the conclusion that either the feature, event, or process is specifically excluded by 
regulation; the probability of the feature, event, and process falls below the 
regulatory criterion; or omission of the feature, event, and process does not 
significantly change the magnitude and time of the resulting radiological 
exposures to the reasonably maximally exposed individual, or radionuclide 
releases to the accessible environment. 
How Addressed 
The above criterion permits an exclusion argument for FEPs that are not consistent with the 
regulations because of waste characteristics, repository design, or site characteristics, provided 
there is adequate rationale and justification. Additionally, a FEP may be excluded from TSPA-
LA if it is demonstrated that the likelihood of a specific occurrence is below the quantitative 
probability of one chance in 10,000 of occurring over a period of 10,000 years. The final 
criterion permits exclusion of FEPs that do not significantly change radiological exposure to the 
reasonably maximally exposed individual and release to the accessible environment, provided 
there is adequate technical basis in accompanying discussions or calculations, including the use 
of either bounding or representative estimates. The sequence implemented in excluding a SZ 
FEP is provided in Section 6.1. Generally, a regulatory-type screening criterion is examined 
first, followed by a screening rationale based on either a low-probability or a low-consequence 
criteria. In Section 6.2 are brief discussions, labeled as Screening Arguments, providing the 
rationale behind excluding a FEP. A summary of Screening Arguments and the exclusion 
criterion is provided in Section 7, Table 7.1-1. 
4.3 REGULATORY BASIS FOR NRC GUIDANCE 
This scientific analysis report complies with the NRCs criteria for FEP screening, given in 10 
CFR Part 63 [156605]. The criteria that can be used to exclude a FEP from TSPA-LA are given 
in the following subsections. 
4.3.1 Low-Probability Criterion 
The low-probability criterion is explicitly stated in 10 CFR Part 63, Section 114(d) [156605]: 
Consider only events that have at least one chance in 10,000 of occurring over 
10,000 years. 
and supported by 10 CFR Section 63.342 [156605]: 
DOEs performance assessments should not include consideration of very 
unlikely features, events, or processes, i.e., those that are estimated to have less 
than one chance in 10,000 of occurring within 10,000 years of disposal. 

The low-probability criterion (i.e., very unlikely FEPs) is stated as less than one chance in 
10,000 of occurring in 10,000 years (10-4/104 year). As explained in Assumption 5.2, an 
equivalence of 10-8 annual-exceedance probability is assumed by the DOE. 
Furthermore, it is stated in Section 63.342 [156605] that: 
DOE's assessments for the human intrusion and ground-water protection 
standards should not include consideration of unlikely features, events, and 
processes, or sequences of events and processes, i.e., those that are estimated to 
have less than one chance in 10 and at least one chance in 10,000 of occurring 
within 10,000 years of disposal. 
As explained in Assumption 5.2, this criterion for unlikely FEPs corresponds to an annualized 
probability of less than 10-5, but greater than or equal to 10-8, which is the lower boundary for 
very unlikely events. 
4.3.2 Low-Consequence Criteria 
Criteria for low-consequence screening arguments are provided in 10 CFR Part 63 [156605], 
Section 114(e) and (f), which indicates that performance assessments shall: 
(e) Provide the technical basis for either inclusion or exclusion of specific 
features, events, and processes in the performance assessment. Specific features, 
events, and processes must be evaluated in detail if the magnitude and time of the 
resulting radiological exposures to the reasonably maximally exposed individual, 
or radionuclide releases to the accessible environment, would be significantly 
changed by their omission. 
(f) Provide the technical basis for either inclusion or exclusion of degradation, 
deterioration, or alteration processes of engineered barriers in the performance 
assessment, including those processes that would adversely affect the 
performance of natural barriers. Degradation, deterioration, or alteration processes 
of engineered barriers must be evaluated in detail if the magnitude and time of the 
resulting radiological exposures to the reasonably maximally exposed individual, 
or radionuclide releases to the accessible environment, would be significantly 
changed by their omission. 
This is supported by 10 CFR 63.342 [156605]: 
DOEs performance assessments need not evaluate, the impacts resulting from 
any features, events, and processes or sequences of events or processes with a 
higher chance of occurrence if the results of the performance assessments would 
not be changed significantly. 

The terms significantly changed and changed significantly are undefined terms in the NRCs 
regulations. The absence of significant change is inferred for FEPs screening purposes to be 
equivalent to having negligible or no effect. Because the relevant performance measures differ 
for different FEPs (e.g., effects on performance can be measured in terms of changes in 
concentrations, flow rates, travel times, or other measures as well as overall exposure to the 
reasonably maximally exposed individual (RMEI), and release to the accessible environment), 
there is no single quantitative test of significance. 
Some FEPs have a beneficial effect on the TSPA, as opposed to an adverse effect. As identified 
in 10 CFR 63.102(j) [156605], the concept of a performance assessment includes that: 
The features, events, and processes considered in the performance assessment 
should represent a wide range of both beneficial and potentially adverse effects on 
performance (e.g., beneficial effects of radionuclide sorption; potentially adverse 
effects of fracture flow or a criticality event). Those features, events, and processes 
expected to materially affect compliance with [10 CFR] 63.113(b) or be potentially 
adverse to performance are included, while events (event classes or scenario 
classes) that are very unlikely (less than one chance in 10,000 over 10,000 years) 
can be excluded from the analysis.  
The Yucca Mountain Review Plan, NUREG-1804 (NRC 2003 [163274], Section 2.2.1), states 
that: 
In many regulatory applications, a conservative approach can be used to decrease 
the need to collect additional information or to justify a simplified modeling 
approach. Conservative estimates for the dose to the reasonably maximally 
exposed individual may be used to demonstrate that the proposed repository 
meets U.S. Nuclear Regulatory Commission regulations and provides adequate 
protection of public health and safety. The total system performance 
assessment is a complex analysis with many parameters, and the U.S. Department 
of Energy may use conservative assumptions to simplify its approaches and data 
collection needs. However, a technical basis  must be provided. 
On the basis of these statements, those FEPs that are demonstrated to have only beneficial effects 
on the radiological exposures to the reasonably maximally exposed individual, or radionuclide 
releases to the accessible environment, can be excluded on the basis of low consequence because 
they have no adverse effects on performance. 
4.3.3 By-Regulation Criteria 
Regulations that specify characteristics, concepts, and definitions may serve as the basis for 
exclusion of FEPs by regulation. These include the characteristics, concepts and definitions 
pertaining to the reference biosphere and geologic setting (see Section 4.3.3.1), climatic cycle 
(see Section 4.3.3.1), and the RMEI (see Section 4.3.3.2). Explicit in 10 CFR Section 63.305(c) 
[156605] is the ability to predict the evolution of a future geologic and hydrologic setting and 
climatic condition given current knowledge of these natural processes. 

Also pertinent are characteristics, concepts, and definitions that must be considered during the 
FEP screening, such as the areal extent of the accessible environment and of the controlled area, 
and the spatial relationship to the distance from the repository to the RMEI. These terms define 
or imply accompanying geographical constraints or constrain the future state of the geologic 
setting and evaluate whether there is a potentially significant consequence of such events. 
4.3.3.1 Reference Biosphere, Geologic Setting, and Climate 
NRC regulations 10 CFR Part 63, [156605] and Environmental Protection Agency (EPA) 
regulations 40 CFR Section 197.15 (64 FR 46976 [105065]) specify assumptions (which, in 
effect, serve as criteria) pertinent to screening many of the SZ FEPs regarding the reference 
biosphere and geologic setting. Per 10 CFR Section 63.2 [156605], the reference biosphere is 
defined as: 
Reference biosphere means the description of the environment inhabited by the 
reasonably maximally exposed individual. The reference biosphere comprises the 
set of specific biotic and abiotic characteristics of the environment, including, but 
not necessarily limited to, climate, topography, soils, flora, fauna, and human 
activities. 
An assumption pertaining to the characteristics of the reference biosphere is presented in 
10 CFR Section 63.305(a) [156605]: 
Features, events, and processes that describe the reference biosphere must be 
consistent with present knowledge of the conditions in the region surrounding the 
Yucca Mountain site. 
This assumption is important in that it echoes the regulations at 10 CFR Section 63.305(b) 
[156605] that: 
DOE should not project changes in society, the biosphere (other than climate), 
human biology, and increase or decreases of human knowledge or technology. 
Consequently, by definition, changes to soils, topography, flora, fauna, and human activities 
must be consistent with present knowledge of the conditions in the region. 
Furthermore, 10 CFR Section 63.305(d) [156605] states that: 
Biosphere pathways must be consistent with arid or semi-arid conditions. 
With regard to evaluation of changes in the geologic setting and climate, 10 CFR Section 
63.305(c) [156605] states that: 
DOE must vary factors relating to the geology, hydrology, and climate, based 
upon cautious, but reasonable assumptions, consistent with present knowledge of 

factors that could affect the Yucca Mountain disposal system in the next 10,000 
years. 
This criterion requires that evolution of the geologic and hydrologic system and climate cycle be 
considered based on present knowledge of the factors that could affect the Yucca Mountain 
disposal system. 
Guidance to assumptions pertaining to the characteristics of the reference biosphere and geologic 
setting, and adopted in this report, is presented in the Yucca Mountain Review Plan, Final Report 
(NRC 2003 [163274]), Section 2.2.1.3.12.4 (2)): 
Specific features, events, and processes have been included in the analyses, and 
appropriate technical bases have been provided for inclusion or exclusion, in 
compliance. 
4.3.3.2 Reasonably Maximally Exposed Individual (RMEI) 
The characteristics of the RMEI to be used in exposure calculations are given at 10 CFR Section 
63.312 (a, b, c, d, and e) [156605]. Pertinent to the SZ FEPs is the criteria in 10 CFR Section 
63.312(a) [156605] that the RMEI: 
Lives in the accessible environment above the highest concentration of 
radionuclides in the plume of contamination. 
For the SZ FEPs, the distance from the repository to the receptor is a criterion of primary 
interest. From 10 CFR Section 63.302 [156605]: 
Accessible environment means any location outside the controlled area. 
Moreover, the controlled area is defined as: 
(1) The surface area, identified by passive institutional controls, that 
encompasses no more than 300 square kilometers (km2). It must not extend 
farther 
(i) south than 36 40' 13.6661" north latitude, in the predominant direction of 
ground water flow; and 
(ii) than 5 km from the repository footprint in any other direction; and, 
(2) The subsurface underlying the surface area. 
The preamble to 10 CFR 63 (66 FR 55732 [156671], p. 55753) states that: 
At distances less than 18 km to the Yucca Mountain site, there is evidence of 
intermittent or temporary occupation in modern (historic) times in and around the 
sitefor prospecting or ranching. There also are a number of Native American 
archeological sites reported throughout Nevada Test Site (NTS) closer to the site 
than the Lathrop Wells location. However, the literature indicates that these were 

never permanently occupied, and most were abandoned by the end of the 1800s. 
Overall, the literature suggests many reasons for the absence of permanent 
inhabitation at distances much closer than 18 km to the siteunfavorable 
agricultural conditions, inhospitable terrain, the scarcity of mineral resources, and 
limitations on water availability. 
These definitions and concepts indicate that the RMEI is located no closer than 18 km to the 
south in the direction of groundwater flow and over a contaminated groundwater plume (in 
accordance with 10 CFR 63.312 (a, b, c, d, and e) [156605]) and that the limit of the controlled 
area is no greater than 5 km from the repository in any other direction (as specified at 10 CFR 
63.302 [156605]). 
4.4 CODES AND STANDARDS 
This analysis report falls under the requirements outlined for Disposal of High-Level Radioactive 
Wastes in a Geologic Repository at Yucca Mountain, Nevada given in the 10 CFR Part 63 
[156605]. 

5. ASSUMPTIONS 
For each assumption made in this analysis, a description of where it is applied and the 
justification for the assumption is discussed in the following subsections. 
5.1 ASHFALL LEACHING AND SZ TRANSPORT 
The following assumptions are made to estimate the potential impact of leaching contaminants 
from ashfall on the release to the accessible environment (FEP 1.2.04.07.0B, Section 6.2.4). 
A volcanic eruption occurs immediately after waste emplacement. 
Justification: This is equivalent to assuming that the volcanic eruption occurs immediately after 
waste emplacement, thus maximizing the impact of short-lived radionuclides, with regard to the 
timing of the release, contributing to radionuclide exposure to the RMEI. No further verification 
is needed. 
5.2 PROBABILITY CRITERION 
The following assumption is applicable to FEPs related to seismic and igneous activity. They 
include FEPs 1.2.04.02.0AIgneous activity changes rock properties (Section 6.2.3); 
1.2.04.07.0BAsh redistribution in groundwater (Section 6.2.4); 1.2.10.01.0AHydrologic 
response to seismic activity (Section 6.2.7); 1.2.10.02.0AHydrologic response to igneous 
activity (Section 6.2.8); 2.2.06.01.0ASeismic activity changes porosity and permeability of rock 
(Section 6.2.16); 2.2.06.02.0ASeismic activity changes porosity and permeability of faults 
(Section 6.2.17); and 2.2.06.02.0BSeismic activity changes porosity and permeability of 
fractures (Section 6.2.18). 
For post-closure naturally occurring FEPs, it is assumed that the probability criterion can also be 
expressed as an annual exceedance probability, which is defined as the probability that a 
specified value (such as ground motions or fault displacement) will be exceeded during one year. 
More specifically, a stated probability screening criterion of one chance in 10,000 in 10,000 
years (10-4/104 year) is assumed equivalent to a 10-8 annual-exceedance probability or annual-
exceedance frequency, and a stated definition of unlikely events as having one chance in 10 in 
10,000 years (10-1/104 year) of occurring is assumed equivalent to a 10-5 annual-exceedance 
probability or annual-exceedance frequency. 
Justification: The definition of annual exceedance probability is taken from (CRWMS M&O 
2000, Glossary [142321]) and the following justification also is presented in that referenced 
document. The assumption of equivalence of annual-exceedance probability is appropriate if the 
possibility of an event is equal for any given year. This satisfies the definition of a Poisson 
distribution as  a mathematical model of the number of outcomes obtained in a suitable 
interval of time and space, that has its mean equal to its variance  (Merriam-Webster 1993, p. 
899 [100468]). This is inferred to mean that naturally occurring, infrequent, and independent 
events can be represented as stochastic processes in which distinct events occur in such a way 
that the number of events occurring in a given period of time depends only on the length of the 
time period. The use of this assumption is justified in Characterize Framework for Seismicity 

and Structural Deformation at Yucca Mountain, Nevada (CRWMS M&O 2000 [142321]), which 
indicates that assuming that the behavior of the earth is generally Poissonian or random is the 
underlying assumption in all probabilistic hazard analyses. 
In other words, naturally occurring events (e.g., earthquakes, meteorite impacts) are considered 
as independent events with regard to size, time, and location. Although there may be cases 
where sufficient data and information exist to depart from this assumption, the Poissonian model 
is generally an effective representation of nature and represents a compromise between the 
complexity of natural processes, availability of information, and the sensitivity of results of 
engineering relevance. Consequently, for natural processes that occur over long time spans, 
assuming annual equivalence over a 10,000-year period (a relatively short time span) is 
reasonable and consistent with the basis of probabilistic hazard analyses. Therefore, no further 
confirmation is required. 
5.3 EVOLUTION OF THE GEOLOGIC SETTING AND CLIMATE 
Potential and naturally occurring geologic and climatic events (but perhaps not necessarily the 
magnitude) have occurred at least once in the past within the geologic record used as the basis 
for the TSPA-LA. 
Justification: This assumption is justified because it is consistent with the regulation used as 
direct input. At 10 CFR Section 63.305(c) [156605], DOE is directed to vary factors related to 
the geology, hydrology, and climate based upon cautious, but reasonable assumptions consistent 
with present knowledge of factors that could affect the Yucca Mountain disposal system over the 
next 10,000 years. 
See also the discussion on the regulatory concepts for reference biosphere and geologic setting 
provided in Section 4.3.3.1. Because it is required by regulation, no further confirmation is 
necessary. 
The implication of this assumption is that any discernible impacts or processes related to past 
events on the site setting are presumably reflected in the present knowledge of natural processes 
that form the basis of the TSPA. If the subject FEP phenomena are not reflected or discernible in 
the data used to describe past settings, they are either of low consequence or low probability 
and can be excluded from consideration. 
Use: This assumption is used throughout and is particularly germane for FEPs 1.3.07.01.0A 
Water table decline (Section 6.2.9); 1.3.07.02.0AWater table rise affects SZ (Section 6.2.10); 
2.2.06.01.0ASeismic activity changes porosity and permeability of rock (Section 6.2.16); 
2.2.06.02.0ASeismic activity changes porosity and permeability of faults (Section 6.2.17); 
2.2.06.02.0BSeismic activity changes porosity and permeability of fractures (Section 6.2.18); 
2.2.08.01.0AChemical characteristics of groundwater in the SZ (Section 6.2.25); and 
2.2.08.03.0AGeochemical interactions and evolution in the SZ (Section 6.2.26). It is 
particularly germane to FEPs related to processes or phenomena that, speculatively, could affect 
future states of the system, but for which the magnitude and/or coupling to the effect on the 
repository is not well defined, or for which consequences in present time are known to be minor. 

6. ANALYSIS 
6.1 APPROACH 
To ensure clear documentation of the treatment of potentially relevant future states of the system, 
the DOE has chosen to adopt a FEP analysis and scenario development process based on the 
methodology developed by Cranwell et al. (1990 [101234]) for the NRC. The approach is 
fundamentally the same as that used in many performance assessments including DOEs Waste 
Isolation Pilot Plant (DOE 1996 [100975]), PAs by the Nuclear Energy Agency, and by other 
radioactive waste programs internationally (e.g., Skagius and Wingefors 1992 [101018]). 
Regardless of the method chosen for the performance assessment, the FEP analysis process 
involves (a) the development of a FEP list, and (b) the screening of the FEPs for inclusion or 
exclusion. 
The development of the Yucca Mountain FEP list for LA is documented in the Enhanced Plan 
for Features, Events, and Processes (FEPs) at Yucca Mountain (BSC 2002 [158966] and 
supplemented by the KTI Letter Report Response to Additional Information Needs on TSPAI 
2.05 and TSPAI 2.06 (Freeze 2003 [165394], Section 3.2). Forty-six (46) FEPs relevant to the 
SZ were identified for assignment and analysis by knowledgeable SZ subject-matter experts, the 
results of which are presented in this analysis report. These FEPs were identified in the 
preliminary TSPA-LA FEP list (DTN: MO0307SEPFEPS4.000 [164527]) and were revised (see 
italicized changes in Table 1.2-1) during subsequent evaluation by the SZ subject-matter experts. 
Alternative classification and assignments of the FEPs are entirely possible but would still be 
based on subjective judgment. Alternative approaches for determining probabilities and 
consequences used as a basis for screening are discussed in Section 6.2 under the individual FEP 
analyses. 
The NRC requires the consideration and evaluation of FEPs as part of the performance 
assessment activities. More specifically, the NRC regulations allow the exclusion of FEPs from 
the TSPA if they can be shown to be of low probability or of low consequence. The specified 
criteria can be summarized in the form of the two following FEP screening statements. 
1) The event has at least one chance in 10,000 of occurring over 10,000 years (see 10 CFR 
63.114(d) [156605]). 
2) The magnitude and time of the resulting radiological exposure to the RMEI, or radionuclide 
release to the accessible environment, would be significantly changed by its omission (see 
10 CFR 63.114(e and f) [156605]). 
Additionally, the Acceptance Criteria in the Yucca Mountain Review Plan (NRC 2003 [163274], 
Section 2.2.1.2.1.3) calls for evaluating the FEPs based on the regulations. This criterion can be 
summarized in the form of a third FEP screening statement. 
3) The FEP is not excluded by regulation. 

If there are affirmative conditions for all three screening criteria, the FEP is Included in the 
TSPA-LA model. If there is a negating condition in any of the three screening criteria, the FEP 
is Excluded from the TSPA-LA model. 
Evaluation of the FEPs against these screening statements may be done in any order. In practice, 
by-regulation criteria were examined first, and then either low probability or low consequence 
criteria were examined. FEPs that were retained on one criterion (e.g., regulatory guidance) 
were also considered against the other criteria (probability and consequence). Consequently, the 
application of the analysts judgment regarding the order in which to apply the criteria does not 
affect the final decision. Allowing the analyst to choose the most appropriate order to apply the 
criteria prevents needless work, such as developing quantitative probability arguments for low-
consequence events or complex consequence models for low-probability events. 
Regardless of the specific approach chosen to perform the screening, the screening process is in 
essence a comparison of the FEP against the set of criteria specified in Section 4.3. 
Consequently, the outcome of the screening is independent of the particular methodology or 
assignments selected to perform the screening. 
If applicable, alternative conceptual models and uncertainty are addressed in the supporting 
documentation cited in the individual FEP evaluations. For included FEPs, alternative 
conceptual models are incorporated into the TSPA-LA based on their development and 
evaluation in the supporting model report. For excluded FEPs, the discussions of the alternative 
conceptual models from the supporting model report are cited in the screening decision for each 
FEP. 
6.2 ANALYSIS OF SZ FEPS 
The following subsections summarize the screening of SZ FEPs. For Included FEPs, the TSPA 
disposition describes the technical basis for and the implementation of the FEP within the TSPA-
LA models. For Excluded FEPs, the screening argument describes the technical basis relevant to 
the exclusion criteria. In cases where a FEP covers multiple technical areas and is shared with 
other FEP AMRs, this analysis report provides only a partial technical basis for the screening of 
the FEP. The full technical basis for these shared FEPs is addressed collectively by all of the 
sharing FEP AMRs. 
6.2.1 Fractures (1.2.02.01.0A) 
FEP Description: Groundwater flow in the Yucca Mountain region and transport of 
any released radionuclides may take place along fractures. The 
rate of flow and the extent of transport in fractures are influenced 
by characteristics such as orientation, aperture, asperity, fracture 
length, connectivity, and the nature of any linings or infills. 
Descriptor Phrases: Fractures in the SZ; Fractures (characteristics); Fractures (infills) 
Screening Decision: Included 

Related FEPs: 1.2.02.02.0A, 1.2.10.01.0A, 2.2.03.01.0A, 2.2.03.02.0A, 
2.2.06.01.0A, 2.2.06.02.0A, 2.2.06.02.0B, 2.2.07.13.0A, 
2.2.10.04.0A, 2.2.12.00.0B 
TSPA Disposition: 
Groundwater flow through fractures in the volcanic units is included in the Saturated Zone Flow 
and Transport (SZFT) model (SZ Flow and Transport Model Abstraction, BSC 2003 [167651], 
Section 6.2). Groundwater flow through fractures in the volcanic units is modeled in the Site 
Scale Saturated Zone Flow Model (BSC 2003 [166262], Sections 6.3.3, 6.5.1, 7, 8, and Figures 
6.4-1 and 6.2-2) using an effective continuum approach (BSC 2003 [166262], Section 6.5.1) 
implemented in the numerical code FEHM V 2.20 (STN: 10086-2.20-00, LANL 2003 [161725]). 
In the SZ Transport Abstraction Model and the SZ one-dimensional (1-D) Transport Model (both 
discussed in BSC 2003 [167651], Section 6.5) variability in the groundwater specific discharge, 
due to variability in fracture permeability and orientation, is modeled by scaling the base case 
specific discharge flow field (BSC 2003 [166262], Section 8) with the stochastically sampled 
scaling parameters for groundwater specific discharge (GWSPD), and horizontal anisotropy in 
the volcanic units (HAVO), to stochastically produce 3-D flow fields. Additionally, the 
characteristics of the fracture properties such as fracture orientation, aperture size, degree of 
infilling, and tortuosity are modeled through the following probabilistically modeled parameters; 
groundwater specific discharge (GWSPD), flowing interval spacing in volcanics (FISVO), 
flowing interval porosity in the volcanic units (FPVO), longitudinal dispersivity (LDISP), 
horizontal anisotropy in the volcanic units (HAVO), colloid partitioning coefficients in the 
volcanics (COLVO), and the sorption coefficients onto colloids (Kd_Pu_Col, Kd_Am_Col, 
Kd_Cs_Col). The above parameters are described in the BSC 2003 ([167651], Sections 6.5.2.1, 
6.5.2.4, 6.5.2.5, 6.5.2.9, 6.5.2.10, 6.5.2.12, and 6.5.2.15). 
6.2.2 Faults (1.2.02.02.0A) 
FEP Description: Numerous faults of various sizes have been noted in the 
Yucca Mountain Region and in the repository area in specific. 
Faults may represent an alteration of the rock permeability and 
continuity of the rock mass, alteration or short-circuiting of the 
flow paths and flow distributions close to the repository, and 
represent unexpected pathways through the repository. 
Descriptor Phrases: Faults (displacement); Faults (dip-slip); Faults (strike-slip); Faults 
(detachment); Faults in the SZ 
Screening Decision: Included 
Related FEPs: 1.2.02.01.0A, 1.2.10.01.0A, 2.2.03.02.0A, 2.2.06.01.0A, 
2.2.06.02.0A, 2.2.06.02.0B, 2.2.07.13.0A, 2.2.12.00.0B 

TSPA Disposition: 
Geologic features and hydrostratigraphic units are explicitly included in the SZ Flow and 
Transport Model Abstraction (BSC 2003 [167651], Section 6.2) in a configuration that accounts 
for the effects of existing faults, based on the hydrogeologic framework model (HFM). As 
discussed in Site-Scale Saturated Zone Flow Model (BSC 2003 [166262], Section 6.4), the HFM 
represents faults and other hydrogeologic features (such as zones of hydrothermal alteration) that 
affect SZ flow. Model configuration of these discrete features is developed in BSC 2003 
([166262], Section 6.3.2) and accounts for fault dip, strike, slip and detachment. Faults in the 
model area can dip at almost any angle, but most are high-angle faults. Given numerical flow 
model resolution, faults were treated as vertical features. Faults deemed important to flow near 
Yucca Mountain were modeled explicitly in the numerical SZ flow model. Important thrust 
faults were represented by repeating hydrogeologic units in the HFM. 
The offsets of hydrostratigraphic units across major faults are incorporated into the model, and 
some key faults (e.g., Solitario Canyon fault, Highway 95 fault, and Fortymile Wash structure) 
are explicitly included as high- or low-permeability features. Model parameters, including 
horizontal anisotropy in the volcanic units (HAVO) and groundwater specific discharge 
(GWSPD), implicitly include the potential impacts of faults on groundwater flow and are 
modeled probabilistically to account for the uncertainty in hydrologic properties associated with 
faults and fractures in the volcanic units. The above two parameters are described in Sections 
6.5.2.1 and 6.5.2.10 of BSC 2003 ([167651], Section 6.5.2.1 and 6.5.2.10). A more detailed 
description of the manner in which specific faults have been addressed is provided in the 
Supplemental Discussion for this FEP in this SZ FEP report. 
Supplemental Discussion: 
Faults fall under several distinct categories based on their hydrological impact on SZ flow paths 
and distributions (BSC 2003 [166262], Table 12). A list of the modeled faults (also denoted as 
features in BSC 2003 [166262], Section 6.4) aggregated under their hydrologic categories is 
given below. Note in the Supplemental Discussion of FEP 2.2.03.02ARock properties of host 
rock and other units, a list of all features, including faults, developed in BSC 2003 ([166262]) is 
given accompanied with a figure depicting their location. 
(1) Zones of permeability enhancement parallel to faults and zones of permeability 
reduction perpendicular to faults 
 Crater Flat FaultThis is a linear feature running north-south in the western half of 
the model, starting south of Claims Canyon and terminating near Highway 195, 
almost halfway between the western boundary of the Solitario Canyon. Vertically it 
extends from the top to the bottom of the model. 
 Solitario Canyon Fault ZoneA north-south trending linear feature just to the west 
of Yucca Mountain. Vertically it extends from the top to the bottom of the model. 
 Solitario Canyon Fault, East BranchA north-northeast trending linear feature just 
to the west of Yucca Mountain. Vertically, it extends from the bottom of the model 
to the top of the model. 

 Highway 95 Fault (West)This is a linear feature in the lower half of the western 
portion of the model. It is east-southeast trending. Vertically, it extends from the 
bottom to the top of the model. 
 Solitario Canyon Fault, West BranchA north-northeast trending linear features 
just to the west of Yucca Mountain. Vertically, it extends from the bottom of the 
model to the top of the model. 
(2) Fault Zones with enhanced permeability 
 Bare Mountain FaultThis is a northwest- to southeast-trending linear feature in the 
southwestern corner of the model. Vertically, it extends from the bottom to the top of 
the model. 
Imbricate Fault ZoneThis is a highly faulted area bounded in the west by the Ghost 
Dance fault, south by the Dune Wash, east by the Paintbrush Canyon fault, and to the 
north by the Drillhole Wash. Vertically, it extends from the top of the model down 
through the middle volcanics to the top of the undifferentiated units. 
(3) Faults representing regions of lower permeability caused by hydrothermal 
alteration 
 Northern Zone (entire Claim Canyon, Calico Hills, and Shoshone Mt.)This zone 
is wedge-shaped, spanning almost the entire northern boundary (except the western 
corner of the northern boundary) and approximately the upper fourth of the eastern 
boundary. Vertically, it extends from the top to the bottom of the model. 
 Northern Crater Flat ZoneThis wedge-shaped zone is at the northern third of the 
western boundary of the model. Vertically, it extends from the top to the bottom of 
the model. 
 Claim Canyon CalderaThese zones span much of the northern boundary of the 
model, extending south as triangular shapes and terminating north of the Yucca 
Wash. Vertically, it extends from the top to the bottom of the model. 
 Shoshone Mt. ZoneThese two zones are in the northeastern corner of the model. 
They extend from the top of the carbonate aquifer up to the top of the model. 
Vertically, it extends from the top to the bottom of the model. 
 Calico Hills ZoneThese two zones are near the eastern end of the model, south of 
the Shoshone Mountain Zones, at approximately the same northing as the Yucca 
Wash. Vertically, it extends from the top to the bottom of the model. 
6.2.3 Igneous Activity Changes Rock Properties (1.2.04.02.0A) 
FEP Description: Igneous activity near the underground facility causes extreme 
changes to rock stress and the thermal regime, and may lead to 
rock deformation, including activation, creation and sealing of 
faults and fractures. This may cause changes in the rock 
hydrologic and mineralogic properties. Permeabilities of dikes and 
sills and the heated regions immediately around them can differ 
from those of country rock. Mineral alterations can also change 
the chemical response of the host rock to contaminants. 

Descriptor Phrases: Igneous activity (rock properties in the UZ); Igneous activity (rock 
properties in the SZ) 
Screening Decision: ExcludedLow consequence 
Related FEPs: 1.2.10.02.0A, 1.2.06.00.0A, 1.2.04.07.0A 
Screening Argument: 
Volcanism and igneous activity within the Yucca Mountain region has undergone two 
developmental phases. Silicic volcanism was dominant between 15 and 11 million years ago 
(m.y.a.), coincident with plate extension and an episode of major caldera formation in the Great 
Basin Region. As extension rates declined, silicic volcanism was replaced with basaltic 
volcanism. Basaltic volcanic caldera building and igneous activity within Yucca Mountain 
region commenced between 13 and 11 m.y.a. Post-caldera building igneous activity within the 
Yucca Mountain peaked approximately 7 m.y.a. Volcanism and igneous activity within the 
Yucca Mountain region is now in a relatively quiescent phase; any future igneous activity in the 
Yucca Mountain region will be basaltic in origin (Characterize Framework for Igneous Activity 
at Yucca Mountain, Nevada, BSC 2003 [163769], Section 6.2). The reduction in igneous 
activity is coupled with a reduction in basaltic intrusions within SZ stratigraphic units. Thus 
changes in existing SZ rock properties due to future basaltic intrusions will be less than the 
cumulative effect of igneous intrusions that occurred over the last 13 to 11 million years. 
Basaltic intrusions due to igneous activity will typically be minimal and highly localized and 
thus cause minimal to localized changes in the physical properties (e.g., lower permeability of 
the intrusion relative to the matrix of the non-welded units) of the intruded rock. This is 
supported by investigations at the Grants Ridge analog sites, which indicate that basaltic 
intrusion produced only localized formation of volcanic glass within the contact zone (Synthesis 
of Volcanism Studies for the Yucca Mountain Site Characterization Project, CRWMS M&O 
1998 [105347], Section 5, p.74 referenced in DTN: MO0310INPDEFEP.000 [DIRS 165880]). 
Investigations of basaltic intrusions at Paiute Ridge (Carter Krogh and Valentine 1996 [160928], 
pp. 7 through 8 referenced in DTN: MO0310INPDEFEP.000 [DIRS 165880]) suggest that 
igneous activities altered rock properties to only a few tens of centimeters to, at most, a meter 
perpendicular to an intruding dike. Since the SZ contains completely saturated pores, heat 
transfer will occur through both conduction and convection. The heat produced from the dike, 
which is a primary component in mineral alteration, will be transferred more efficiently away 
from the dike in the SZ compared to the UZ. Therefore, it is inferred that mineral alteration in 
the SZ due to a dike intrusion will be similar to that of the Grants Ridge analog sites, where 
mineral alteration is constrained to a narrow width on either side of the dike. 
The limited, meter scale effects of mineral alteration, and possible change in flow paths, are 
insignificant when compared to the multi-kilometer scale changes in path length that results from 
existing considerations of uncertainty in fracture properties and flowing intervals. Flow and 
transport in the SZ is dominated by existing fractures, fracture clusters and fracture spacing, 
collectively labeled as flowing intervals in the SZFT model abstraction (SZ Flow and Transport 
Model Abstraction, BSC 2003 [167651], Section 6.3). The SZFT model evaluates uncertainties 

assigned to flowing interval properties such as horizontal anisotropy in the volcanic units, 
flowing interval spacing, flowing interval porosity in the volcanics, and longitudinal dispersion 
(BSC 2003 [167651], Table 6-8). Transport times through the SZ are quite sensitive to 
parameter uncertainty associated with flowing interval properties (only uncertainty in the 
specific discharge scaling parameter, which is meant to account for increased specific discharge 
due to a wetter climate, produces a greater variation in transport times). As an example, 
parameter uncertainty in flowing interval spacing results in transport times that vary by several 
thousands of years (Arnold et al. 2000 [166335]). The uncertainty incorporated in the horizontal 
anisotropy (which accounts for maximum and minimum stresses imposed on fracture clusters 
and faults and their orientation) results in transport paths varying by several kilometers (BSC 
2003 [167651], Figure 6-6). Thus the incorporated parameter uncertainty in fracture and fault 
regional properties overwhelms any changes in SZ transport times and flows paths associated 
with localized changes in mineral alteration. 
Given the scale of the SZFT model (18 km to the discharge point and the modeled 500-m model 
grid discretization) and the uncertainties in the flowing interval properties incorporated in BSC 
2003 ([167651], Table 6-8), highly localized effects caused by igneous activity will not have 
significant impacts on the flux at the compliance boundary. As a result, any localized changes in 
flow or transport properties due to igneous activity (inclusive of geochemical changes) will not 
have a significant effect on the exposure to RMEI. A more detailed discussion of FEPs related to 
igneous activity is given in Errata for Features, Events and Processes: Disruptive Events (BSC 
2004 [167720], Section 6.2.2). Therefore, changes in rock properties due to igneous activity can 
be excluded based on low consequence because they will not significantly change radiological 
exposures to the RMEI or radionuclide releases to the accessible environment. 
6.2.4 Ash Redistribution in Groundwater (1.2.04.07.0B) 
FEP Description: Following deposition of contaminated ash on the surface, 
contaminants may leach out of the ash deposit and be transported 
through the subsurface to the compliance point. 
Descriptor Phrases: Leaching of contaminated ash; Redistribution of contaminated ash 
(pumping) 
Screening Decision: ExcludedLow consequence 
Related FEPs: 1.2.04.06.0A, 2.3.02.02.0A 
Screening Argument: 
The probability of a volcanic eruption intersecting the repository is approximately 1.3E-8/year 
(Characterize Framework for Igneous Activity at Yucca Mountain, Nevada, BSC 2003 [163769], 
Sections 7.1,7.2). The probability of such an eruption occurring during the first 10,000 years, 
when the dose rate is potentially significant, is approximately 1.3E-4 (see Supplemental 
Discussion for this FEP in this SZ FEP report). If a volcanic eruption were to occur within the 
repository entraining radioactive waste, contaminated radionuclide bearing ash deposited on the 

surface could leach and be transported through the UZ and SZ to the compliance point. 
Assuming the contents of six waste commercial spent nuclear fuel (CSNF) packages are 
entrained in the volcanic eruption (which is the median number of packages brought to the 
surface by a single volcanic eruption intersecting one drift (Number of Waste Packages Hit by 
Igneous Intrusion, BSC 2003 [161851], Attachment A)) and that all of the waste is uniformly 
distributed in the ash blanket on the ground surface, the resulting estimated conditional dose rate 
is 20.5mrem/year. The probability that a volcanic eruption will occur within the repository 
during the first 10,000 years of waste emplacement is 1.3E-04. The resulting probability-
weighted dose rate due to leaching of radionuclides from contaminated ash becomes less than 
2.66E-03 mrem/year (as calculated in the Supplemental Discussion for this FEP in this SZ FEP 
report). In addition, the conservative assumption is made that all radionuclides derived from the 
volcanic ash blanket are captured in the hypothetical pumping wells of the RMEI. This is 
consistent with the TSPA nominal class scenario model, in which radionuclide contamination of 
groundwater in the SZ is assumed to be completely captured in the groundwater usage of the 
hypothetical future farming community. This is significantly less than the probability-weighted 
doses resulting from other igneous pathways during this period (Total System Performance 
Assessment for the Site Recommendation, CRWMS M&O 2000 [153246], Section 4.2). The 
effects of non-uniform distribution of the ash blanket are addressed in the Supplemental 
Discussion. The effects of ashfall on SZ transport is excluded on the basis of low consequence 
because they will not significantly change radiological exposures to the RMEI or radionuclide 
releases to the accessible environment. 
Supplemental Discussion: 
For this screening analysis, it is assumed that the contents of six waste packages are entrained in 
the volcanic eruption and that all of the waste resulting from the eruption is uniformly distributed 
in the ash blanket on the ground surface. Six waste packages are the median number of packages 
brought to the surface by a single volcanic eruption intersecting one drift (BSC 2003 [161851], 
Attachment A). The six waste packages are assumed to contain CSNF, which is the most 
common type of waste package in the repository. The radionuclide inventory in the waste 
packages is assumed to be the average for CSNF at the time of waste emplacement. This is 
equivalent to assuming that the volcanic eruption occurs immediately after waste emplacement, 
an assumption that conservatively maximizes the impact of short-lived radionuclides. The 
inventories for key radionuclides in the erupted ash are shown in Table 6.2-1. The volcanic ash 
blanket is assumed to be entirely and evenly distributed in the 18-km region between the 
repository and the RMEI. This assumption maximizes the quantity of radionuclides that is 
available for transport via the SZ to the hypothetical pumping wells of the RMEI. 
It is assumed that the radionuclides in the ash layer are entirely and immediately dissolved in the 
infiltrating groundwater along the 18-km flow path. It is also conservatively assumed that 
radionuclides are transported without radioactive decay in the SZ; however, radioactive decay is 
accounted for during transport from the ground surface to the water table. In addition, the 
conservative assumption is made that all radionuclides derived from the volcanic ash blanket are 
captured in the hypothetical pumping wells of the RMEI. This is consistent with the TSPA 
nominal scenario class model, in which radionuclide contamination of groundwater in the SZ is 
assumed to be completely captured in the groundwater usage of the hypothetical future farming 

community. The same groundwater volume that is used determine radionuclide concentrations 
in the TSPA-LA, 3,000 acre-ft/year (10 CFR 63 [156605], Subpart 63.332 (3)), is used to 
determine the expected value withdrawn from the RMEIs well in this analysis. 
Transport of radionuclides from the ash blanket to the water table is conceptualized to occur by 
one-dimensional flow downward through alluvium. The groundwater velocity in the UZ above 
the water table is calculated using an average volumetric moisture content of 0.1. This is a 
reasonable average value for vegetated native soil in the region (Johnson et al. 2002 [165069], 
Figure 16) and is likely lower than what would occur under washes in which intermittent 
infiltration occurs. The calculation of groundwater velocity also uses an infiltration flux of 
2.21 mm/year, which is the estimated recharge rate along Fortymile Wash in the upper Jackass 
Flats reach (Recharge and Lateral Groundwater Flow Boundary Conditions for the Saturated 
Zone Site-Scale Flow and Transport Model, BSC 2001 [164648], Table 6.1.3-1). In addition, the 
thickness of the UZ is assumed to be 100 m, which is an approximate value in the region near the 
hypothetical pumping wells, based on the depth to the water table in well NC-EWDP-19P 
(DTN: GS010908312332.002 [163555]). The average transport time from the ground surface to 
the water table for radionuclides is calculated as: 
(Eq. 1) 
where t is the average transport time [T], is the retardation factor in the alluvium [-], z is the 
depth to the water table [L], is the moisture content [-], and q is the recharge flux [L/T]. The 
retardation factor for flow in the UZ is defined by Freeze and Cherry (1979 [101173], p. 404) as: 
(Eq. 2) 
where is the dry bulk density of the alluvium [M/L3], is the sorption coefficient [L3/M], 
and is the total porosity of the alluvium [-]. The value of bulk density used in the analysis is 
1.91 g/milliliter (ml) and the porosity is 0.3, which are the expected values (SZ Flow and 
Transport Model Abstraction, BSC 2003 [167651], Table 6-8). The median values for the 
sorption coefficients for the radionuclides, as taken from BSC 2003 ([167651], Table 6-8), are 
shown Table 6.2-1. Radionuclides will experience radioactive decay during transport in the UZ 
to the water table. The remaining activity of radionuclides after transport through the UZ, which 
can be derived from Domenico and Schwartz (1991 [100569], Equation 14.11), is: 
(Eq. 3) 

Ash 
where A is the activity at the water table [Curies], is the activity in the ash [Curies], and T0.5 
is the half-life of the radionuclide and t is the average transport time. Substituting Equations 1 
and 2 into Equation 3 yields the activity of each radionuclide at the water table in Curies. 
Note that radionuclides of Pu and Am are treated as irreversibly attached to colloids in the 
analysis presented here. Consequently, the retardation factor used is the median value for the 
retardation factor of colloids in alluvium (BSC 2003 [167651], Table 6-8). Radionuclides 
irreversibly attached to colloids migrate more rapidly than radionuclides reversibly attached to 
colloids, so this assumption is conservative with regard to estimated dose. 
The SZ is conceptualized as a simplified one-dimensional flow system between the repository 
and the accessible environment as shown in Figure 6.2-1. In the simplified conceptual model of 
radionuclide transport in the SZ, uniform, one-dimensional flow is assumed to deliver the 
radionuclide mass to the hypothetical pumping wells of the RMEI at a steady rate. A transport 
time of 800 years, for a non-sorbing species, from the water table located just below the 
repository footprint, is taken from the analysis of SZ transport using the three-dimensional SZ 
Transport Abstraction Model (BSC 2003 [167651], Figure 6-28). The 800-year travel time is the 
approximate median transport time among the multiple realizations of SZ transport. The 
resulting idealized radionuclide mass breakthrough curve is shown in Figure 6.2-2. Note that the 
first radionuclide mass is released to the accessible environment at the time of first arrival at the 
water table (shown as time zero in Figure 6.2-2). The duration of the breakthrough curve is 800 
years, at which time the most upstream of the radionuclide mass arrives. The average (and also 
peak) concentration of the non-sorbing radionuclide in the water supply of the hypothetical 
farming community is calculated by dividing the total radionuclide mass delivered to the SZ 
from the contaminated ash by the water usage over the 800 years. For those radionuclides that 
experience sorption and retardation in the SZ, the distribution of radionuclide mass arrival at 18 
km is spread over a longer period of time, as indicated by the example shown in Figure 6.2-2. A 
retardation factor of two means that the arrival of radionuclide mass at 18 km is spread over 
about 1600 years and the radionuclide mass flux is one half of that for the non-sorbing species. 
Figure 6.2-1. Cross-Section Diagram of Simplified One-Dimensional Model for Transport in the SZ of 
Radionuclides Leached from Volcanic Ash 

Figure 6.2-2. Example of Idealized Radionuclide Mass Breakthrough Curves at 18-km Distance Resulting 
from Volcanic Ash Leaching for Non-Sorbing and Sorbing Radionuclides 
The estimate of dose rate from this simplified analysis is shown in Table 6.2-1. The 
representative volume of water for each radionuclide is calculated as the product of the expected 
annual groundwater usage, the 800-year travel time, and the retardation factor. The 
concentration is calculated by dividing the activity of the radionuclide at the water table by the 
representative water volume. The dose rate is calculated as the product of the average 
concentration and the Biosphere Dose Conversion Factor (BDCF) for each radionuclide, as 
shown in Table 6.2-1. Note that the values of the BDCF for these radionuclides are taken for 
present climatic conditions, which are higher than the values for future, wetter conditions. The 
resulting estimated dose is thus higher and conservative relative to estimated future conditions 
for most of the next 10,000 years. 
The resulting estimated conditional total dose rate is 20.5 mrem/year. As shown in Table 6.2-1, 
the calculated dose rate from shorter-lived radionuclides (e.g., 90Sr and 137Cs) is zero due to 
decay during transport to the water table following leaching from the ash layer. The largest 
single contribution to the total calculated dose rate is from 239Pu (21.4 mrem/year). As noted 
above, the dose from 239Pu is probably overestimated due to the conservative assumption that Pu 
is transported as irreversibly attached to colloids. 99Tc, 129I, 234U, and 237Np contribute smaller 
but significant amounts to the total calculated dose rate. 
This conditional dose rate should be weighted by the probability of the occurrence of a volcanic 
eruption to evaluate its potential impact on the overall exposure to RMEI. Volcanic eruptions at 
Yucca Mountain are unlikely; BSC 2003 ([163769], Sections 7.1, 7.2) concludes that the mean 
annual frequency of igneous intrusion into the repository footprint is 1.7E-08. The probability of 
eruption, conditioned to an intrusion, is less, 1.3E-08 (not all hypothetical igneous intrusions 
would result in an eruption at the repository). Adopting the 1.3E-08/year value and assuming 
that future igneous activity at Yucca Mountain is a Poisson process, there is approximately a 

1.3E-04 probability of an eruptive igneous event at Yucca Mountain in the next 10,000 years. 
This event is equally likely to occur in any year during the 10,000-year period, and the 
probability that the event has already occurred (and that groundwater is contaminated) rises from 
1.3E-08 in the first year to 1.3E-04 after 10,000 years. A rigorous approach to estimating the 
probability-weighted dose through time would require evaluating consequences of events at each 
year and summing the probability-weighted doses, as done in the TSPA-Site Recommendation 
(SR) for doses incurred by direct exposure to a contaminated ash layer (CRWMS M&O 2000 
[153246], Section 4.2). However, it is conservative to assume that the dose rate estimated for an 
igneous event occurring in the first year is representative of events that might occur at any time 
in the first 10,000 years. In fact, the first-year event provides an upper bound on the radionuclide 
inventory available for later events. The probability of an eruptive igneous event occurring 
during the first 10,000 years is 1.3E-04, which yields a probability-weighted dose rate of 
approximately 2.66E-03 mrem/year for leaching of radionuclides from contaminated ash and 
contamination of the groundwater used by the RMEI. This is significantly less than the 
probability-weighted doses resulting from other igneous pathways during this period (CRWMS 
M&O 2000 [153246], Section 4.2). 
One assumption of the simplified analysis summarized in Table 6.2-1 is that the blanket of ash is 
uniformly deposited on the ground surface above the aquifer. A plausible alternative scenario is 
that the ash could be redistributed, for example, by running water in Fortymile Wash before 
leaching of radionuclides. A thicker deposit of ash in one area would lead to higher 
concentrations of radionuclides in that area of the SZ and consequent higher peak dose rate from 
the production of contaminated groundwater. The increase in the estimated peak dose rate would 
be approximately proportional to the increased thickness of the ash deposit relative to the 
average thickness due to erosional and depositional processes. In other words, if the ash deposit 
were redistributed such that it was five times thicker at the downstream end of Fortymile Wash 
relative to the average ash thickness, then the peak dose rate would be about five times greater. 
This would be a significant increase relative to the estimated conditional dose rate of 20.5 
mrem/year. However, considering the probability weighting presented above and the numerous 
conservative simplifying assumptions used in the analysis, this aspect of ash redistribution has 
low consequence to repository performance. In conclusion ashfall is excluded from the SZ on 
the basis of low consequence because it will not significantly change radiological exposures to 
the RMEI or radionuclide releases to the accessible environment. 

Table 6.2-1. Screening Estimate of Dose from the SZ for Leaching from Volcanic Ash, Conditional on Eruptive Release 
Radio-
nuclide 
Curies per 
packagea 
Curies 
Released 
Expected 
Kd 
(ml/g)b 
Expected 
Rf 
Half-life 
(years) 
Curies at 
water 
table 
Water 
Volume (L) 
Concen-
tration 
(picoCi/L) 
BDCF 
(mrem/yr 
per pCi/L)c 
Dose Rate 
(mrem/yr) 
C-14
6.12E+00
3.67E+01 
0.0
1.0
5.73E+03
2.12E+01
2.96E+12
7.16E+00
9.06E-03
6.49E-02
Sr-90
3.48E+05
2.09E+06
210.0
1338.0
2.91E+01
0.00E+00
3.96E+15
0.00E+00
1.64E-01
0.00E+00
Tc-99
1.29E+02
7.74E+02
0.0
1.0
2.13E+05 
7.36E+02 
2.96E+12 
2.49E+02
2.21E-03
5.50E-01
I-129
3.09E-09
1.85E+00
0.0
1.0
1.57E+07
1.85E+00
2.96E+12
6.25E-01
3.37E-01
2.11E-01
Cs-137
5.19E+05
3.11E+06
728.0
4635.9
3.00E+01
0.00E+00
1.37E+16
0.00E+00
4.87E-01
0.00E+00
U-232
2.27E-01
1.36E+00
4.6
30.3
7.20E+01
0.00E+00
8.97E+13
0.00E+00
5.78E00
0.00E+00
U-233
5.61E-04
3.37E-03
4.6
30.3
1.59E+05
1.85E-03
8.97E+13
2.06E-05
1.74E00
3.58E-05
U-234
1.10E+01
6.60E+01
4.6
30.3
2.45E+05
4.48E+01
8.97E+13
4.99E-01
1.21E00
6.04E-01
U-236
2.51E+00
1.51E+01
4.6
30.3
2.34E+07 
1.50E+01 
8.97E+13
1.67E-01
1.08E00
1.80E-01 
U-238
2.66E+00
1.60E+01
4.6
30.3
4.47E+09
1.60E+01
8.97E+13
1.78E-01
1.08E00
1.92E-01
Np-237
3.26E+00
1.96E+01
6.4
41.7
2.14E+06
1.84E+01
1.24E+14
1.48E-01
6.92E00
1.02E+00
Pu-238
2.64E+04
1.58E+05
N/A
34.0
8.77E+01
0.00E+00
1.01E+14
0.00E+00
4.67E00
0.00E+00
Pu-239
2.71E+03
1.63E+04
N/A
34.0
2.41E+04
1.95E+02
1.01E+14
1.93E+00
9.16E00
1.77E+01
Pu-240
4.73E+03
2.84E+04
N/A
34.0
6.54E+03
2.35E-03
1.01E+14
2.33E-05
8.93E00
2.08E-04
Am-241
2.84E+04
1.70E+05
N/A
34.0
4.32E+02
0.00E+00
1.01E+14
0.00E+00
6.78E00
0.00E+00
Am-243
2.51E+02
1.51E+03
N/A
34.0
7.38E+03
8.01E-04
1.01E+14
7.93E-06
9.43E00
7.48E-05 
20.5 
a Source: 2003 [161961], calculated from Table 21 and Attachment III. 
b Source: BSC 2003 [167651], Table 6-8. 
c Source: BSC 2003 [164403], Table 6.2-5. 
Note that the probability of eruptive release of radionuclides is about 1.3E-8/year (BSC 2003 [163769], Section 7.2). 
.

6.2.5 Hydrothermal Activity (1.2.06.00.0A) 
FEP Description: Naturally-occurring high-temperature groundwater may induce 
hydrothermal alteration of minerals in the rocks through which the 
high-temperature groundwater flows. 
Descriptor Phrases: Hydrothermal alteration of the SZ 
Screening Decision: ExcludedLow consequence 
Related FEPs: 1.2.04.02.0A, 1.2.10.02.0A, 2.2.10.02.0A, 2.2.08.03.0A, 
2.2.10.08.0A, 2.2.10.03.0A 
Screening Argument: 
The presence of silica, calcite, and clay vein deposits and mineral replacement assemblages 
indicate the presence of past hydrothermal activity associated with both silicic and basaltic 
caldera building within the Basin and Range province. Evidence of hydrothermal mineral 
alteration is seen in the Calico Hills, Claim Canyon, and along the south Flank of Shoshone 
Mountain (Geochemical and Isotopic Constraints on Groundwater Flow Directions and 
Magnitudes, Mixing, and Recharge at Yucca Mountain, Nevada, BSC 2003 [167211], Figure 3); 
all three past hydrothermal areas are not along the SZ flow path and lie north and north east of 
Yucca Mountain (Characterize Framework for Igneous Activity at Yucca Mountain, Nevada, 
BSC 2003 [163769], Figure 3). Hydrothermal mineral replacement is distinguished from 
deuteric alteration, which, as tuff cools, causes exsolving gaseous and aqueous components 
precipitating opal, calcite and zeolites in lithophysae and intermittent veins (Yucca Mountain Site 
Description, CRWMS M&O 2000 [151945], Section 4.9). Deuteric, not hydrothermal, mineral 
alteration is ubiquitous in the vicinity of Yucca Mountain. Yucca Mountain is located outside 
the caldera margin that encompasses Claim Canyon and Shoshone Mountain; hence it was never 
near this ancient hydrothermal source (BSC 2003 [163769], Figure 3). 
The likelihood of future hydrothermal activity to develop within the vicinity of SZ flow paths is 
conditioned to future volcanic and igneous activity. Silicic volcanism was dominant between 15 
and 11 million years ago (m.y.a.), coincident with plate extension and an episode of major 
caldera formation in the Great Basin Region. Crustal extension rates started to decline about 13 
m.y.a.; this progression in crustal evolution resulted in silicic volcanism being replaced with 
basaltic volcanism. Basaltic volcanic caldera building and igneous activity within the Yucca 
Mountain region commenced between 13 and 11 m.y.a. Post-caldera building igneous activity 
within the Yucca Mountain peaked approximately 7 m.y.a. Igneous intrusions in the areally 
extensive Yucca Mountain region, once extensive in nature, are now in a relatively quiescent 
phase (BSC 2003 [163769], Section 6.2). Future igneous activity within the Crater Flat basin 
will typically cause minimal, highly localized basaltic dike-like intrusions with average widths 
on the order of one meter (BSC 2003 [163769], Section 6.3.2). This is supported by 
investigations at the Grants Ridge analog sites, which indicate that basaltic intrusion produced 
only localized formation of volcanic glass within the contact zone (Synthesis of Volcanism 

Studies for the Yucca Mountain Site Characterization Project, CRWMS M&O 1998 [105347], 
Section 5, p.74 referenced in DTN: MO0310INPDEFEP.000 [DIRS 165880]). Investigations of 
basaltic intrusions at Paiute Ridge (Carter Krogh and Valentine 1996 [160928], pp. 7 through 8 
referenced in DTN: MO0310INPDEFEP.000 [DIRS 165880]) suggest that igneous activities 
altered rock properties to only a few tens of centimeters to, at most, a meter perpendicular to an 
intruding dike. Associated hydrothermal activity is conditioned to these localized igneous 
events. It is inferred, given the lack of evidence of any past hydrothermal along the Crater Flat 
basin (BSC 2003 [167211], Figure 3 ), coupled with the relatively small widths of igneous 
intrusions that would intersect the SZ flow domain, that any associated hydrothermal activity 
produced from future igneous activity will be minimal (localized) and of low consequence to the 
long term and regional SZ flow paths. In summary, hydrothermal activity is excluded based on 
low consequence because it will not significantly change radiological exposures to the RMEI or 
radionuclide releases to the accessible environment. 
6.2.6 Large-Scale Dissolution (1.2.09.02.0A) 
FEP Description: Dissolution can occur when any soluble mineral is removed by 
flowing water, and large-scale dissolution is a potentially important 
process in rocks that are composed predominantly of water-soluble 
evaporite minerals, such as salt. 
Descriptor Phrases: Large-scale dissolution in the SZ 
Screening Decision: ExcludedLow consequence 
Related FEPs: 1.3.07.01.0A, 1.3.07.02.0A, 2.2.08.01.0A, 2.2.08.03.0A, 
2.2.08.06.0A 
Screening Argument: 
Large-scale dissolution can be excluded from the Saturated Zone Flow and Transport (SZFT) 
models because evaporites, in particular halite with a solubility of 360,000 mg/L at P=1 
atmosphere (atm) and T=25C (Freeze and Cherry 1979 [101173], p. 106), are not dominant 
minerals in the formations along the simulated transport pathways. The hydrogeologic 
framework model, which is based on the available geologic information from the Yucca 
Mountain region (DAgnese et al. 1997 [100131] and United States Geological Survey (USGS) 
2003 [165176], Figures 6-2, 6-18), uses 19 hydrogeologic units to represent the geologic system. 
Of these hydrogeologic units, the carbonates are the most soluble in groundwater (solubility of 
90-500 mg/L depending on the pCO2 at P=1 atm and T=25C (Freeze and Cherry 1979 [101173], 
p. 106)), and the permeability of these units is primarily due to solution channels and fractures. 
The transport pathways in the SZ are primarily through volcanic tuffs and alluvial material (Site-
Scale Saturated Zone Flow Model, BSC 2003 [166262], Section 6.6.2.3), which largely consists 
of disaggregated tuffaceous rocks (Site-Scale Saturated Zone Transport, BSC 2003 [166260], 
Attachment I and Section 8). The carbonate units are included in the SZFT model, and the 
assigned permeabilities are representative of the existing solution channels and fractures. The 
carbonate units along the SZ transport path are located well below the water table (USGS 2003 

[165176], Figures 6-2 and 6-18). New extensive dissolution cavities are unlikely to develop at 
depths well below the water table where CO2 has been depleted. Even if they did form, there 
would be no detrimental effect on the simulated performance of the site as transport occurs near 
the water table in the upper volcanic, lower volcanic and alluvial aquifers. 
The volcanic rocks present at the water table are not readily soluble in water; their solubility is 
low enough that large-scale dissolution does not occur. Volcanic rocks tend to weather to clay 
minerals with a relatively small amount of silica going into solution. Freeze and Cherry (1979 
[101173], p. 106) give the solubility of quartz 12 mg/L at P=1 atm and T=25C. Secondary 
permeability in volcanic rocks is primarily due to the formation of open fractures. Fracture flow 
and transport are explicit features of the site-scale 3-D saturated flow and transport model. 
In summary, transport of radionuclides will primarily take place in the relatively insoluble 
volcanic units located near the surface of the water table and well above the more soluble 
carbonate units where large-scale dissolution could take place. Given unusually drier climatic 
conditions the water table may drop to lower levels from its current potentiometric surface. 
While unlikely, there is mineralogical evidence that the maximum decline in the water table from 
current levels could be at most 300 m (see FEP 1.3.07.01.0AWater table decline). This 
potential decline still retains the water table several hundreds of meters above the carbonate 
aquifer along the simulated SZ transport paths (USGS 2003 [165176], Figures 6-2 and 6-18). 
Current groundwater withdrawal rates and their effects on water table elevations in the Jackass 
Flats hydrographic basin (La Camera et al. 1999 [103283], pp. 17 through 22; Young 1972 
[103023]) are insignificant. Based on these observations, it is concluded that future withdrawal 
rates will not cause the water table to drop along the transport paths to the more soluble 
carbonate units. In conclusion, large-scale dissolution is excluded based on low consequence 
because it will not significantly change radiological exposures to the RMEI or radionuclide 
releases to the accessible environment. 
6.2.7 Hydrologic Response to Seismic Activity (1.2.10.01.0A) 
FEP Description: Seismic activity, associated with fault movement, may create new 
or enhanced flow pathways and/or connections between 
stratigraphic units, or it may change the stress (and therefore fluid 
pressure) within the rock. These responses have the potential to 
significantly change the surface- and groundwater- flow directions, 
water level, water chemistry and temperature. 
Descriptor Phrases: Water table elevation; Saturated flow and pathways in the SZ 
Screening Decision: ExcludedLow consequence 
Related FEPs: 1.2.02.01.0A, 1.2.02.02.0A, 2.2.06.01.0A, 2.2.06.02.0A, 
2.2.06.02.0B 

Screening Argument: 
Water table elevations can change from a few centimeters to several tens of meters in response to 
seismic activity. The change in water table elevation can also affect (1) SZ flow and pathways, 
if the change in water table elevations are extensive enough to change the regional 
potentiometric surfaces, and (2) groundwater geochemistry, as the displaced water is moved into, 
and interacts with, rocks composed of different mineralogy. Seismic activity is caused by 
changes in the stress imposed on the country rock, fault and fracture formation and fault 
displacement. A transient change in water table elevations is associated with the passage of the 
seismically perturbed surface wave that passes through the region. Long-term changes in water 
table elevations are associated with seismically induced permanent changes in pore pressure and 
volume strain or permanent changes in regional permeability. In the Basin and Range Province, 
which includes the Yucca Mountain region, seismic activity is ultimately controlled by the more 
areally extensive tectonic activity, a result of broad crustal plate extension. Tectonic activity in 
the Yucca Mountain region is in a waning phase with the focal point moving westward (Errata 
for Features, Events and Processes: Disruptive Events, BSC 2004 [167720], Section 6.2.1.1). 
Because seismic activity is closely associated with tectonic activity, a decline in tectonic activity 
coincides with a decline in the frequency and intensity of seismic activity. Investigations of 
analog sites and numerical studies demonstrate seismic activity within the Yucca Mountain 
region will not change long-term (i.e., over the 10,000-year regulatory period) regional SZ 
groundwater flow patterns, water chemistry, and temperatures. A brief summary of these 
investigations is given below. 
Given the predicted decline in seismic activity over a 10,000-year time frame, the Probabilistic 
Seismic Hazard Analysis (PSHA) expert elicitation group (Probabilistic Seismic Hazard 
Analyses for Fault Displacement and Vibratory Ground Motion at Yucca Mountain, Nevada, 
CRWMS M&O 1998 [103731], Section 8) determined mean displacement in intact rock is less 
than 0.1 cm for a 1E-08 annual exceedance probability in the area between Solitario Canyon and 
the Ghost Dance Faults. Consequently, no significant new faults and fractures, which would 
have the potential to create new flow paths or significantly change the existing flow paths and 
flow directions, are expected in the intact rock. 
Because it is unlikely a seismic event will create new faults, movement along existing faults is of 
primary interest. Expert elicitation from the PSHA group estimate a 2-m to 4-m mean fault 
displacement, at an annual-exceedance probability of 1E-8, as the upper limit for the majority of 
faults within the Yucca Mountain region (CRWMS M&O 1998 [103731], Section 8.2). The 
exception is the predicted 10-m mean displacement along the Solitario Canyon fault at an 
annual-exceedance probability of 1E-8, (CRWMS M&O 1998 [103731], Figure 8-3). Several 
investigations have been conducted to estimate the hydrologic response to a fault displacement 
(i.e., change in water table elevations) given predicted fault displacements. One investigation 
was performed by the National Research Council (NRC 1992 [105162], Chapter 5 referenced in 
DTN: MO0310INPDEFEP.000 [DIRS 165880]). This group estimated the maximum changes 
in water table elevations over a 10,000-year period in response to seismic activity, which 
presumes some degree of fault displacement. They estimated fault displacement using two 
modeling approaches: (1) a dislocation approach, where zones of extension on one side of a fault 
are balanced by compression across the fault; and (2) the more realistic changes in the regional 

stress approach caused by normal fault slippage in regions of extension. The regional stress 
approach evaluated the effect of stress on pore pressure, which is dependent on the elastic 
properties of the bulk rock and the mineral grains. Both models resulted in a transient change in 
water table elevation given a seismic event in the Yucca Mountain region. However, the extent 
of the rise differed for both models. Adopting the dislocation model, the maximum rise in the 
water table would be approximately 10 m. Results from the regional stress approach resulted in 
a maximum water table rise of 50 m. The later approach assumes realistically conservative rock 
and mineral elastic properties. The panel concluded that regardless of which approach is taken, 
the maximum water table rise given a seismic event would be less that 50 m. Given the 
Councils study, it is inferred that a 10-m slip along Solitario Canyon fault, which could 
implicitly impose the maximum change in volume stress strain changes on pore pressure, would 
result in no more than a 50-m rise in the water table (see related FEP 2.2.06.02.0ASeismic 
activity changes porosity and permeability of faults). 
Several other numerical studies estimate the hydrologic response due to fault displacement. 
Analysis performed by Gauthier et al. (1996 [100447], pp. 163 through 164) indicates that the 
greatest strain-induced changes in water table elevation occur with strike-slip faults. Simulations 
of the timing, magnitude, and duration of water table rise indicate a maximum rise of 50 m 
within an hour of the simulated event. The simulated system returns to steady-state conditions 
within 6 months. Gauthier et al. 1996 [100447] concluded that: 
In general, seismically induced water table excursions caused by poroelastic 
coupling would not influence the models presently being used to determine long-
term performance of a repository at Yucca Mountain; therefore, we excluded 
them from the total-system simulations. 
The magnitude and transient nature of the simulated, seismically induced, water table rise is 
consistent with other estimates and observations. Numerical simulations performed by Carrigan 
et al. (1991 [100967]) modeled tectonohydrologic responses based on an earthquake associated 
with a 1-m fault slip, which produced a simulated water table rise of 2 m to 3 m for a water table 
500 m below ground surface. Extrapolation to a more hypothetical event of a 4-m slip results in 
a transient rise of 17 m near the fault (Carrigan et al. 1991 [100967], p. 1159). 
Investigations focusing on the potentiometric hydrologic response given changes in rock 
properties adjacent to the fault demonstrate that the changes in water table elevation are transient 
and local in nature. Carrigan et al. (1991 [100967]) modeled a 100-m wide fracture zone 
centered on a vertical fault, such that vertical permeability was increased by three orders of 
magnitude. The results of that model indicate transient water table rise of up to 12 m, in the 
fracture zone, with 1 m of slip. These results indicate seismic pumping due to changes in 
permeability along faults would produce a short-term and transient water table rise and for the 
10,000-year time scale, would not change regional flow directions or flow paths. 
Observations of changes in water table elevation given recorded seismic events support the 
conclusions drawn from the above numerical studies. The United States Geological Survey 
(USGS) has produced an Open File Report 93-73 (OBrien 1993 [101276]) wherein water level 
fluctuations at Yucca Mountain due to earthquakes in the region were analyzed. Water table 

fluctuations range from 90 centimeter (cm) associated with a 7.5 magnitude earthquake near 
Landers, California (CA) (approximately 420 km from Yucca Mountain) to 20 cm for a second 
quake of 6.6 magnitude near Big Bear Lake, CA (approximately 400 km from Yucca Mountain). 
More notably, a 5.6 magnitude quake at Little Skull Mountain (approximately 23 km from Yucca 
Mountain) resulted in a maximum fluctuation of 40 cm, with water levels in another well 
declining approximately 50 cm over the 3 days following the earthquake. Water levels in that 
well returned to pre-quake levels over a period of about 6 months. Thus, observed changes in 
the water table from seismic events in the outlying vicinity are relatively minor and transient in 
nature. 
A seismic event can alter in-situ rock hydrologic properties along a relatively narrow zone 
adjacent to the fault, labeled herein as a zone of alteration. The zone of alteration can be on 
the order of a few meters to tens of meters wide adjacent to the fault (see FEPs 2.2.06.01.0A
Seismic activity changes porosity and permeability of rock and 2.2.06.02.0ASeismic activity 
changes porosity and permeability of faults). The current perturbed rock properties along zones 
of alteration are in response to the cumulative effects of a highly active seismic past regionally 
imposed on the Basin and Range Province over many millennia. It is inferred, given the 
predicted lower frequencies of future seismic events, hydrologic properties in these zones of 
alterations will not be significantly altered (Detailed discussions on the effects of seismic events 
on rock properties are provided in BSC (2004 [167720], Sections 6.2.1.8 through 6.2.1.11). 
Furthermore, flow and transport in the SZ is dominated by fault orientation and existing 
fractures, fracture clusters and fracture spacing, collectively labeled as flowing intervals in the 
Saturated Zone Flow and Transport (SZFT) model abstraction (SZ Flow and Transport Model 
Abstraction, BSC 2003 [167651], Section 6.3). The SZFT model evaluates uncertainties 
assigned to flowing interval properties such as horizontal anisotropy in the volcanic units, 
flowing interval spacing, flowing interval porosity in the volcanics, and longitudinal dispersion 
(BSC 2003 [167651], Table 6-8). Transport times through the SZ are quite sensitive to 
parameter uncertainty associated with flowing interval properties (only uncertainty in the 
specific discharge scaling parameter, which is meant to account for increased specific discharge 
due to a wetter climate, produces a greater variation in transport times). As an example, 
parameter uncertainty in flowing interval spacing results in transport times that vary by several 
thousands of years (Arnold et al. 2000 [166335]). The uncertainty incorporated in the horizontal 
anisotropy (which accounts for maximum and minimum stresses imposed on faults and fracture 
clusters and their orientation) results in transport paths that vary by several kilometers (BSC 
2003 [167651], Figure 6-6). Thus the incorporated parameter uncertainty for fracture and fault 
properties, on a regional scale, overwhelms any transient changes in SZ transport times and 
flows paths given a localized changes in rock properties residing in the zone of alteration. 
Additionally, the calibration and validation of the base case flow field is based on parameter 
uncertainty and model sensitivity to grid discretization. More specifically, the calibration 
process includes (1) spatially varying multiple flow and transport parameters such as 
permeability, porosity, anisotropy, faults and fault zones, and the orientation and nature of faults 
to measured and interpolated water levels, and (2) sensitivity of the calibrated parameters to grid 
size and grid resolution (Site-Scale Saturated Zone Flow Model, BSC 2003 [166262], Sections 
6.5.3.2, 6.6.1 and 7.0). Grid resolution is based on systematically running the model, then 

comparing results, using grids of differing resolutions (increased or decreased grid 
discretizations in both the horizontal and vertical direction). Given this type of exercise, the grid 
considered suitable for stochastic modeling is one that produces minimal differences in the 
model results compared to results from a grid with increased (i.e., more refined) discretization. 
Given this type of exercise, the appropriate grid discretization used in the SZFT model is for 
500-m grid blocks (uniformly spaced) in the horizontal direction, and 10-m to 550-m non-
uniformly spaced grid blocks in the vertical direction. For the TSPA-LA SZFT model, on a 
regional and long-term scale, the transient hydrologic response due to seismically induced 
changes in the relatively small and discrete zones of alteration is insignificant due to the 
parameter uncertainty incorporated into the SZ model and model scale and grid discretization 
(Seismic effects on rock fault properties adjacent and within faults and zones are discussed in 
FEP 2.2.06.02.0ASeismic activity changes porosity and permeability of faults). 
Results from the above investigations indicate the hydrologic response due to fault displacement 
(i.e. changes in the water table elevation) from predicted seismic events within the Yucca 
Mountain region will be transient and local in nature. 
Lastly, the effect of a seismically induced hydrologic response on SZ groundwater chemistry will 
be insignificant. Groundwater isotopic and geochemical signatures within the Yucca Mountain 
region are indicative of groundwater flow directions and flow paths that have existed over the 
past 10,000 years. Geochemical analysis indicates the current SZ groundwater under the 
repository and along the SZ transport path is paleoclimate recharge water (Geochemical and 
Isotopic Constraints on Groundwater Flow Directions and Magnitudes, Mixing, and Recharge at 
Yucca Mountain, Nevada, BSC 2003 [167211], Section 7.1.2). Flow and transport modeling 
results show good history matching with the geochemical modeled flow patterns and deduced 
mixing relations using hydrochemical and isotopic data (BSC 2003 [167211], Section 7.1.4). 
These isotopic and geochemical signatures indicate changes in groundwater temperatures and 
geochemistry are primarily a result of climatic events and recharge points, followed by 
rock-water interactions. By deduction, the large volume of paleoclimate recharge water 
undergoes more rock-water interactions in the UZ and SZ, and more mixing of waters from 
different flow systems due to climatic events, than the relatively small volume of water that 
contacts a seismically produced zone of alteration. Thus, the large influx of paleoclimate 
recharge waters, now underneath the repository location and along the transport path, represents 
the maximum geochemical and temperature variability in the SZ and overshadows any minor 
change in groundwater geochemistry due to a transient seismically induced event. 
In summary, the SZ hydrologic response due to a future seismic event is negligible over the 
temporal and spatial scale of concern. A seismically induced hydrologic response in the SZ will 
not change long-term flow directions or flow paths and will not have a significant effect on the 
release of radionuclides to the accessible environment. This FEP is excluded based on low 
consequence because it will not significantly change radiological exposures to the RMEI or 
radionuclide releases to the accessible environment. 

6.2.8 Hydrologic Response to Igneous Activity (1.2.10.02.0A) 
FEP Description: Igneous activity includes magmatic intrusions which may alter 
groundwater flow pathways, and thermal effects which may heat 
up groundwater and rock. Igneous activity may change the 
groundwater flow directions, water level, water chemistry, and 
temperature. Eruptive and extrusive phases may change the 
topography, surface drainage patterns, and surface soil conditions. 
This may affect infiltration rates and locations. 
Descriptor Phrases: Water table elevation; Saturated flow and pathways in the SZ 
Screening Decision: ExcludedLow consequence 
Related FEPs: 1.2.04.02.0A, 1.2.06.00.0A, 2.2.08.01.0A, 2.2.08.03.0A 
Screening Argument: 
The effects of igneous intrusions on UZ flow and flow paths, topography, surface drainage 
patterns, surface soil conditions and infiltration rates are addressed in the UZ FEP analysis report 
(Features, Events, and Processes in UZ Flow and Transport, BSC 2003 [164873], Section 
6.7.4). 
Igneous intrusions within the SZ flow domain are expected to be of low consequence to water 
table elevations and SZ flow patterns and flow paths for the following reasons. Several analog 
sites can be used to eliminate the effects of an igneous activity on SZ hydrology. The Paiute 
Ridge intrusive/extrusive center located in the northeastern margin of the Nevada Test Site is one 
example. Paleomagnetic, geochronologic, and geochemical data indicate that the complex 
formed during a brief magmatic pulse representing a single volcanic event (Ratcliff et al. 1994 
[106634]). The vents and associated dike system formed within a north-northwest-trending 
extensional graben provide exposures of a variety of depths of the system including remnants of 
surface lava flows, volcanic conduits, and dikes and sills intruded into tuff country rock at depths 
of up to 300 m. Carter Krogh and Valentines 1996 ([160928], pp. 7 and 8 referenced in 
DTN: MO0310INPDEFEP.000 [DIRS 165880]) investigation of the site suggests that (1) 
igneous activities altered rock properties within only a few tens of centimeters out from the 
rock/dike interface and at most, a meter perpendicular to an intruding dike, and (2) dike location 
and orientation was influenced by the orientation of the local stress field and the presence of 
existing faults. The anisotropic permeability in the SZ observed in the Yucca Mountain region 
has a maximum principal permeability direction of approximately north-northeast, which is 
consistent with the fault and fracture orientation (Ferrill et al. 1999 [118941], p. 1). 
Additionally, the dike margins are parallel and coincident with the primary direction of increased 
or decreased permeability. This parallel to subparallel orientation of dikes and maximum 
principal permeability, coupled with the expected limited affected volume of material around the 
dikes, indicate that dikes, even if differing in permeability, will not significantly affect 
groundwater flow patterns at the mountain scale. 

There are several lines of evidence that support eliminating the effects of an igneous activity on 
long-term changes in water temperature and geochemistry. Analysis of igneous activity at Paiute 
Ridge (Synthesis of Volcanism Studies for the Yucca Mountain Site Characterization Project, 
CRWMS M&O 1998 [105347], Section 5, p. 57 referenced in DTN: MO0310INPDEFEP.000 
[DIRS 165880]) indicates that thermal transfer into adjacent rock due to an igneous activity was 
minimal. Igneous activities at the Grants Ridge site produced only localized formation of 
volcanic glass within the contact zone (CRWMS M&O 1998 [105347], Section 5, p. 74 
referenced in DTN: MO0310INPDEFEP.000 [DIRS 165880]); evidence of any regional 
hydrothermal response was absent. Additionally, Kuiper (1991 [163417]) suggests if a 10-km 
long, 5-km deep, and 100-m wide, disc-shaped dike initially intruded into the SZ, the transient 
rise in the water table due to heat effects would be on the order of 25 m. Studies of natural-
analog sites (CRWMS M&O 1998 [105347], Section 5, pp. 1  2 referenced in 
DTN: MO0310INPDEFEP.000 [DIRS 165880]) support minimal chemical and mineralogical 
alteration (meters to a few tens of meters of the intrusion itself) from the rock intruding dike 
interface due to any future igneous activity within the Yucca Mountain region. Lastly, because 
SZ water chemistry is dominated by the chemical and atmospheric conditions and the large 
volume of paleoclimate recharge waters, the small volume of igneously altered rock would have 
little impact on the global characteristics of SZ water chemistry (see FEPs 2.2.08.01.0A
Chemical characteristics of groundwater in the SZ and 2.2.08.03.0AGeochemical interactions 
and evolution in the SZ). Thus, the regional SZ geochemistry in the Yucca Mountain vicinity 
will not be significantly affected by igneous activity (A more detailed discussion of FEPs related 
to igneous activity is given in Errata for Features, Events and Processes: Disruptive Events 
(BSC 2004 [167720], Section 6.2.2). 
In summary, any igneous intrusions that are expected to occur in the time frame of the regulatory 
period will affect a relatively small volume of the SZ and are likely to have the orientation of the 
intrusive features or parallel to existing features. Consequently, the intrusion will not have a 
significant effect on rock permeabilities at the scale that affects site-wide water table elevations, 
SZ flow and flow paths. Therefore, the hydrologic response to igneous activity is excluded 
based on low consequence because it will not significantly change radiological exposures to the 
RMEI or radionuclide releases to the accessible environment. 
6.2.9 Water Table Decline (1.3.07.01.0A) 
FEP Description: Climate change could produce decreased infiltration (e.g., an 
extended drought), leading to a decline in the water table in the 
saturated zone, which would affect the release and exposure 
pathways from the repository. 
Descriptor Phrases: Climate change (drier); Time-dependent infiltration (decrease); 
Water table elevation 
Screening Decision: ExcludedLow consequence 
Related FEPs: 1.3.01.00.0A, 1.2.09.02.0A, 2.2.08.11.0A 

Screening Argument: 
The primary process affecting water table elevations is the cyclical and climatically driven 
infiltration through the UZ to the SZ (Szabo et al. 1994 [100088]). One can predict relative 
future water table elevations based on several physical lines of evidence, such as mineralogy and 
geochemistry and fossil, glacial and marine records. These records indicate a cyclical rise and 
fall of the water table coincident with the 100,000- to 150,000-year cyclical change in climate 
punctuated by the periodicity of smaller climate cycles ranging between 10,000 to 40,000 years 
(Szabo et al. 1994 [100088], Figure 6; Forester et al. 1996 [100148], p. 52). Reasoned 
arguments are given below for the maximum depth in which the water table could be lowered 
within the next 10,000 years given an unexpectedly dry climate and the effects of a much lower 
water table on transport times. 
Geochemical and isotopic analyses (Geochemical and Isotopic Constraints on Groundwater 
Flow Directions and Magnitudes, Mixing, and Recharge at Yucca Mountain, Nevada, BSC 2003 
[167211], Section 7.1) indicate that SZ groundwater along the projected flow path is between 
10,000 to 16,000 years old (the average mixed age), and its composition reflects recharge that 
occurred up until the late Pleistocene. Groundwater pressures respond much more quickly than 
groundwater geochemistry to changes in boundary conditions (i.e., recharge rates, inflow from 
adjacent boundaries). Consequently, water table elevations are more reflective of the current, 
interglacial, climate pressure pulse. 
Present groundwater elevations in North Americas Basin and Range Province (which includes 
the Yucca Mountain region) are reflective of current arid climatic conditions and the (time 
dependent) decrease in infiltration (i.e., lower recharge) of the interglacial climatic interval. The 
interglacial climatic interval is predicted to persist for the next 400 to 600 years. After the 
interglacial climatic interval, warmer and wetter monsoonal climatic conditions are predicted to 
persist for approximately 900 to 1400 years. It is predicted that a cooler and wetter glacial 
transition climatic condition will follow the brief monsoonal period and will persist for about 
8,500 years (USGS 2001 [158378], Section 7). However, while not predicted in Future Climate 
Analysis (USGS 2001 [158378]), this FEP addresses variability within the interglacial climatic 
interval that may produce an extreme arid condition that could potentially cause the current water 
table to fall significantly. By investigating the geologic, fossil, and mineralogic records, one can 
ascertain the lower bound in which a water table could potentially fall within the next 600 years, 
given extremely unusual and increasingly more arid climatic conditions. 
An indication of past water table elevations can be found by examining calcite crystal 
morphology within saturated and unsaturated fractures (Whelan et al. 1998 [108865]). Calcite 
crystals grown below the water table are dense and elongated, having porosities much less than 
1% (Szabo et al. 1994 [100088]). Calcite crystals grown in unsaturated fractures (above the 
water table) are distinctly different from those grown in saturated fractures (below the water 
table). They are porous (120% porosity), free growing, short (Szabo et al. 1994 [100088]), do 
not fluoresce or phosphoresce, locally display orange growth banding, and have single-phase 
fluid inclusions (Whelan et al. 1998 [108865]). Whelan et al. (1998 [108865]) report evidence of 
calcite crystal growth, indicative of unsaturated conditions in fracture openings, located 100 to 
300 m below the current water table. The evidence suggests the water table dropped to these 

levels at least once during the last 11.6 million years. Szabo et al. 1994 [100088] studied 
evidence of past water table fluctuations in Browns Room, a subterranean air-filled room 
adjacent to the Ash Meadows discharge area. Their investigations indicate the water table 
dropped by at least 6 m from its current level between 92,000 and 53,000 years ago. (Szabo et al. 
1994 [100088] do not give estimates of how much beyond 6 m the water table may have 
declined.) Based on the above findings one can conclude there is a relatively low probability 
that the water table will decline to depths of 300 m. However, if the water table were to fall by 
as much as 300 m, the change in flow path and transport time that a plume would take from the 
repository to the 18-km compliance boundary would be of low consequence. Based on the SZ 
base case flow calculations, the transport path, under current and wetter climatic conditions, is 
confined to the Prow Pass, Bullfrog, and Tram sub-units of the Crater Flat Formation, the Upper 
Volcanic Confining Unit, Upper Volcanic Aquifer, Undifferentiated Valley Fill and Alluvium, 
with most of it going through the Bullfrog (Site-Scale Saturated Zone Flow Model, BSC 2003 
[166262], Section 6.6.2.3). The collective thicknesses of these units along the potential transport 
path are well over 300 m (BSC 2003 [166262], Section 6.5.3.3). The Prow Pass and Bullfrog 
units are the most permeable volcanic units in the flow and transport path (BSC 2003 [166262], 
Table 14). Lowering the water table by as much as 300 m in the volcanic units would put the 
potential transport path primarily in the Tram subunit and potentially in the Lower Volcanic 
Confining unit. The permeability of these units is several orders of magnitude lower than the 
Bullfrog. Therefore, if the water table was lowered by as much as 300 m, transport times would 
be greater than transport through the all Crater Flat sub-units. 
Given the collective alluvium and valley-fill thickness of 400 to 700 m and the uncertainty in 
transport properties through both the undifferentiated valley fill and alluvium units, a potential 
lowering of the water table from its current elevation would not affect predicted transport times. 
The uncertainty as to whether a plume would flow in the alluvium and valley fill or the volcanic 
units, due to a lower water table, is implicitly captured using stochastic simulations of the 
location of the northern and western boundaries of the alluvial units in the SZ Flow and 
Transport Model Abstraction (BSC 2003 [167651], Section 6.5.2.2). 
Additionally, a lowering of the water table would create longer transport pathways through the 
unsaturated zone, thus delaying and potentially reducing the total mass of radionuclides reaching 
the SZ, and create lower hydraulic gradients. Lower gradients in the SZ equate to slower 
groundwater SZ specific discharge rates, which mean longer SZ travel times to the compliance 
boundary. 
Lastly, paleoclimate records indicate arid climatic conditions are short relative to wetter 
conditions. Forester et al.s (1996 [100148], p. 52) investigations of proxy climate records 
indicate climatic conditions during the past 2 million years were much wetter than current 
climatic conditions for about 70 to 80 percent of the time. Szabo et al.s (1994 [100088], Figure 
6) analysis of Searles Lake deposits indicate extreme arid conditions have only occurred twice 
during the past 600,000 years, once around 290,000 years ago and between 10,000 years ago to 
the present. One can infer the water table is now at a low point in the 150,000- to 300,000-year 
climate cycle and will not significantly drop below current groundwater elevations during the 
10,000-year regulatory period. Based on the above evidence, if the water table were to decline, 
the likelihood of it declining 140 to 300 m below its current level is very low. 

Given the above rationale, it is not likely the water table will decline to levels lower than 140 to 
300 m from its present position. However, if the water table were to decline to these levels, the 
overall effect would be to increase SZ transport travel times and thus not adversely affect 
repository performance. Therefore, water table decline is excluded based on low consequence 
because it has no adverse effects on performance. 
6.2.10 Water Table Rise Affects SZ (1.3.07.02.0A) 
FEP Description: Climate change could produce increased infiltration, leading to a 
rise in the regional water table, possibly affecting the release and 
exposure pathways from the repository by altering flow and 
transport pathways in the SZ. A regionally higher water table and 
change in SZ flow patterns might move discharge points closer to 
the repository. 
Descriptor Phrases: Climate change (wetter); Time-dependent infiltration (increase); 
Water table elevation; Saturated flow and pathways in the SZ 
Screening Decision: Included 
Related FEPs: 1.2.09.02.0A, 1.3.01.00.0A, 2.2.08.11.0A 
Screening Argument: 
The TSPA-LA implicitly models a higher water table in the SZ to reflect wetter climatic 
conditions (resulting in an increase in time dependent infiltration) with the use of flux 
multipliers. Flux multipliers are incorporated in the convolution integral method (SZ Flow and 
Transport Model Abstraction, BSC 2003 [167651], Section 6.5). Flux multipliers scale the base 
case saturated zone radionuclide breakthrough curves, effectively modeling the impacts a higher 
water table would have on transport times to the 18-km boundary. Three flux multipliers are 
used to characterize changes in water table elevations reflective of three climatic conditions. 
Current climatic conditions are represented by a flux multiplier of 1.0; for a monsoonal climate 
the multiplier is 2.7; and for a glacial transition climate the multiplier is 3.9 (BSC 2003 
[167651], Table 6-5). An upper bound estimate of SZ transport times to the 18-km boundary, 
reflective of a higher water table produced during a glacial transition climatic condition, is 
conservatively bounded with the use of the 3.9 flux multiplier. The rationale supporting this 
assumption is given below. 
SZ transport times at the 18-km boundary using the 3.9 flux multiplier method (representative of 
a glacial transition climate) have been compared to transport times performed on an alternative 
model domain. The alternative model domain method allows the water table to be 100 m higher 
than present conditions under the repository footprint (Section 6.4.5.1 of Site-Scale Saturated 
Zone Flow Model, (BSC 2003 [166262]), which is the upper estimate the water table would rise 
under the repository given a future glacial transition climatic condition. Conservative and 
sorbing tracer breakthrough curves (BTCs) show initial tracer breakthroughs (the leading edge of 

the BTC) are at least an order of magnitude greater for the alternative model method compared to 
breakthrough using the flux multiplier method. Additionally, BTC trailing edges for the 
alternative model domain are well over an order of magnitude greater compared to those derived 
using a flux multiplier (BSC 2003 [167208], Attachment V and Figures V-1 and V-2). The 
longer transport times using the alternative model are a function of several factors. The higher 
water table incorporated in the alternative model domain enables both types of tracers to pass 
through less permeable upper volcanic confining units, resulting in considerably longer path 
lengths and transport times. The longer transport times in the volcanic units facilitate greater 
matrix diffusion. Additionally, a higher water table promotes longer flow paths through the 
porous alluvium, equating to longer alluvium transport times. Because the flux multiplier 
method results in more rapid radionuclide transport relative to explicitly simulating a higher 
water table, this simplified representation of the effect of climate change on water table 
elevations conservatively estimates the effects of a higher water table on SZ transport times to 
the 18-km boundary. 
6.2.11 Water Management Activities (1.4.07.01.0A) 
FEP Description: Water management is accomplished through a combination of 
dams, reservoirs, canals, pipelines, and collection and storage 
facilities. Water management activities could have a major 
influence on the behavior and transport of contaminants in 
the biosphere. 
Descriptor Phrases: Land use; Water use; Surface activities (water management); 
Radionuclide release to the biosphere (irrigation water) 
Screening Decision: Included 
Related FEPs: 1.4.07.02.0A, 1.4.07.03.0A, 2.3.11.04.0A, 2.2.08.11.0A 
TSPA Disposition: 
For the SZ, this FEP pertains to the impacts on projected SZ flow and transport times due to the 
construction of future water management edifices. The effects of existing water management 
activities on the saturated flow system, while not directly quantifiable, are implicitly 
incorporated in the calibrated heads of the SZ flow model. Future water management activities, 
other than future well withdrawal rates specifically covered in 10 CFR Section 63.332, are 
presumed to be those currently in practice as stated by regulation Section 63.305 [156605], 
which states: 
DOE should not project changes in society, the biosphere (other than climate), 
human biology, or increases or decreases of human knowledge or technology. In 
all analyses done to demonstrate compliance with this part, DOE must assume 
that all of those factors remain constant as they are at the time of submission of 
the license application. 

Water management activities are explicitly included in the biosphere models that determine 
irrigation intensity, fraction of overhead irrigation, and through the biospheres fish and 
plant mathematical sub-models that determine the potential dose to RMEI. This FEP, and its 
impact on the RMEI, is discussed in the Evaluation of Features, Events and Processes for the 
Biosphere Model (BSC 2003 [165843], Section 6.2.9). 
6.2.12 Wells (1.4.07.02.0A) 
FEP Description: One or more wells drilled for human use (e.g., drinking water, 
bathing) or agricultural use (e.g., irrigation, animal watering) may 
intersect the contaminant plume. 
Descriptor Phrases: Radionuclide release to biosphere (drinking water wells); 
Radionuclide release to biosphere (irrigation water wells); Water 
use 
Screening Decision: Included 
Related FEPs: 1.4.07.01.0A, 1.4.07.03.0A, 2.2.07.16.0A, 2.3.11.04.0A, 
2.2.07.12.0A, 2.2.08.11.0A 
TSPA Disposition: 
The effects of wells on the dose to members of the RMEI are included through the volume of 
radionuclide-affected groundwater used by that group (SZ Flow and Transport Model 
Abstraction, BSC 2003 [167651], Sections 6.2). The groundwater system in the vicinity of the 
hypothetical communitys well system is modeled assuming that all the contaminants discharged 
at the 18-km boundary are intercepted by the communitys wells. The total volume extracted 
from all wells (which includes wells used for agricultural, domestic, irrigation, drinking water) to 
be used by the farming community will not exceed 3,000 acre-feet per year (in accordance with 
10 CFR Part 63 Subpart 63.332 (3) [156605]). The volume of extracted well water used to 
determine the concentration of radionuclides is 3,000 acre-feet per year. 
6.2.13 Transport of Particles Larger Than Colloids in the SZ (2.1.09.21.0B) 
FEP Description: Particles of radionuclide-bearing material larger than colloids could 
be entrained in suspension and then be transported in water flowing 
through the SZ. 
Descriptor Phrases: Groundwater rinse in the SZ; Gravitational settling of colloids in 
the SZ 
Screening Decision: ExcludedLow consequence 
Related FEPs: 2.2.08.10.0A 

Screening Argument: 
This FEP deals with particles larger than 1 m, the upper limit in colloidal size particles that 
could potentially transport radionuclide-bearing material. Because radionuclide bearing particles 
larger than 1 m are not considered to move from the waste packages through the Engineered 
Barrier System (EBS) and UZ, these large particles would first have to be formed in the SZ, then 
transported downstream to the compliance boundary. Two processes, precipitation and colloid 
accretion and flocculation, could contribute to the formation of large radionuclide bearing 
particles. Once formed, these larger particles could be entrained (i.e., rinsed) in the groundwater 
downstream for some distance before filtering or settling. 
Horizontal flow is the dominant flow component along the potential SZ transport path. Large 
particles will be carried, horizontally, along contorted flow paths, encountering varying fracture 
widths, fracture asperities and orientations, and less mobile regions. A large particle will bump 
and grind along this less than ideal flow path, losing energy due to frictional forces to the point 
where its velocity will be reduced such that it will settle out or be filtered. It is only possible for 
the smallest of large particles (i.e., slightly larger than a colloid) to be sustained along the entire 
18-km flow path if the upward vertical component of the pore water velocity exceeds the 
particles settling velocity (sv). An estimation of a particles sv is derived using Stokes Law: 
(Eq. 4) 
and the following inputs: 
1. Particle diameter (L) of 1 micron (1E-06 m). 
2. Particle density (Pd) of 2500 kilogram (kg)/m3 (Waste Form and In-Drift Colloids-
Associated Radionuclide Concentrations: Abstraction and Summary, BSC 2003 
[166845], Section 5.10 & 6.3.1). 
3. Water density of (Dw) - 1000 kg/m3 at 20C (Streeter and Wylie 1979 [145287], 
p. 534). 
4. Water dynamic viscosity (V) of 1.005E-03 Ns/m2 at 20C (Viswanath and Natarajan 
1989 [129867], p. 715). 
5. Acceleration of gravity (g) - 9.81 m/s2. 
Using the above inputs (appropriate for 20C), the sv order of magnitude is 8E-07 m/s 
(0.08 m/d). Thus, to keep the smallest of large particles sustained along the entire path length, 
the upward vertical component of the pore water velocity must exceed the sv of 8E-07 m/s. This 
is unlikely for several reasons. 
Most particles larger than colloids will have a sv greater than the 8E-07 m/s, since: 
1. Minor increases in temperature cause a large increase in sv, enabling relatively small 
particles to settle more readily. The temperature range for Yucca Mountain SZ waters is 

approximately 20 to 55C, with the majority of temperatures within the upper 20 to lower 
30C (Site-Scale Saturated Zone Flow Model, BSC 2003 [166262], Section 7.4). The 
temperature dependent density and viscosity of water for this temperature range will 
result in a higher sv. It is viscosity that varies most with temperature. Consequently, the 
variability in sv would most dramatically be increased due to the large variability in 
viscosity. 
2. Most particles will be larger than the upper bound diameter for colloids (1 m) and 
thus have a higher sv than that used in Equation 4. 
3. Using Stokes Law to calculate sustainability of particles in an open solution presumes 
particle settling is unhindered as it moves horizontally, which is not the case in porous 
media. SZ flow is not along open and unhindered flow paths. In the volcanics SZ flow is 
primarily through the Crater Flat group (consisting of the Bullfrog, Tram, and Prow Pass 
units), the Upper Volcanic Aquifer, and the Upper Volcanic Confining Unit, with the 
majority of SZ flow going through the Bullfrog unit (BSC 2003 [166262], 
Section 6.6.2.2). In the Crater Flat group the SZ flow passes through fractured zones 
consisting of rubblized and brecciated material producing large variability in 
permeability. On a regional scale, fracture permeability in the Bullfrog, Tram and Prow 
Pass units ranges over 3 orders of magnitude (BSC 2003 [166262], Section 6.6.1.4). 
Locally, this variability is even greater. This leads to variability in the magnitude of the 
vertical component of pore/fracture water velocity. Thus a large particle, if suspended 
when transported downstream, will encounter low permeability and rubblized zones 
where the vertical flow vector is less than the sv. In these locations large particles will 
settle out. 
4. A calculation of the upward vertical component in two known SZ locations show the sv 
is not exceeded as follows: 
a. The difference between the Carbonate Aquifer head measurements (752.4 m at 
UE-25p#1) and shallower measurements in the same area (730.2 m at UE-25c#1, 
UE-25c#2, UE-25c#3) is about 20 m (BSC 2003 [166262], Table 13). The 
elevation differences are -410 m for UE-25p#1 and about 500 m average for c#1, 
c#2, c#3. This gives an average vertical gradient of 20 m/910 m or 0.022. The 
confining unit between the Carbonate aquifer and the Bullfrog unit (a primary 
flow path) has a mean permeability value of 1E-15 m2 (BSC 2003 [166262], 
Figure 37), converting to hydraulic conductivity (at 20C) gives 10-10 m/s. 
Multiplying by the vertical gradient gives 2.2E-12 m/s for the specific discharge. 
If the effective porosity is 0.01 (SZ Flow and Transport Model Abstraction, BSC 
2003 [167651], Section 6.5.2.), the calculated upward velocity is 2.2E-10 m/s, 
which is less than calculated sv. 
b. The difference between the alluvium head measurement at NC-EWDP 19D and 
NC-EWDP 19P is 5.3 m (USGS 2004 [168473], Table 6-1); the elevation 
difference between these 2 wells is 293 m, yielding a gradient of .018 (5.3 m/293 
m). The mean permeability value for the alluvium is 2E-13 m2 (BSC 2003 

[166262], Table 23), which converted to hydraulic conductivity (at 20C) gives 
5.1 x 10-06m/s. Multiplying this by the vertical gradient gives a specific discharge 
of 4.56E-8 m/s. For the alluvium the mean effective porosity is 0.18 (BSC 2003 
[167651], Table 6-8); multiplying mean porosity by specific discharge gives the 
upward vertical velocity of 2.54E-7 m/s, which is less than the calculated sv. 
5. Laboratory and field measurements on Yucca Mountain tuffs indicate that colloid 
filtering and settling is a mechanism that removes colloid size particles from solution 
(Saturated Zone Colloidal Transport, BSC 2003 [162729], Sections 6.4.2 and 6.5). 
Laboratory experiments performed on 30-cm length core tubes demonstrated that colloids 
stick and settle along fracture surfaces, especially in those fractures oriented 
horizontally and parallel to the flow direction. Results from these laboratory experiments 
are supported with field observations. At the Nevada Test Site, a five-order decrease in 
Pu colloid concentrations was observed in ER-20-5 wells for colloids formed as a result 
of the BENHAM underground nuclear tests. The ER-20-5 wells are located several 
kilometers downstream from the test area (Kersting et al. 1999 [103282]). Physical 
filtering was the process attributed to the loss of colloid mass downstream. Because 
filtering occurs for colloidal size particles, this process will be exacerbated for larger 
particles. 
Transport of particles larger than colloids is screened out on low consequence because (1) no 
radionuclide bearing particles larger than colloids are introduced into the SZ from the UZ 
(Features, Events, and Processes in UZ Flow and Transport, BSC 2003 [164873], Section 
6.3.4), (2) large particles will not be suspended for great distances along the flow paths given the 
variable vertical velocity component that would be encountered along the transport path, and (3) 
the highly variable size, shape, orientation, and roughness of the transporting fracture voids 
promote both settling and filtering. Transport of particles larger than colloids is excluded based 
on low consequence because it will not significantly change radiological exposures to the RMEI 
or radionuclide releases to the accessible environment. 
6.2.14 Stratigraphy (2.2.03.01.0A) 
FEP Description: Stratigraphic information is necessary information for the 
performance assessment. This information should include 
identification of the relevant rock units, soils and alluvium, and 
their thickness, lateral extents, and relationships to each other. 
Major discontinuities should be identified. 
Descriptor Phrases: Rock properties in the SZ; Hydrologic properties in the SZ 
Screening Decision: Included 
Related FEPs: 1.2.02.01.0A, 2.2.03.02.0A, 2.2.07.12.0A, 2.2.07.13.0A, 
2.2.08.01.0A, 2.2.12.00.0B 

TSPA Disposition: 
The stratigraphic (i.e., hydrologic) nature of the rock as it affects flow and transport is 
incorporated into the TSPA-LA site-scale flow and transport models (BSC 2003 [166262], 
Section 6.2). The primary hydrogeologic subdivisions are based on and coincide with (1) 
common permeability and porosity characteristics (on a regional scale) of the rock and (2) 
whether the rocks primary mode of origin is volcanic, clastic, sedimentary (carbonates), or 
alluvial in nature (BSC 2003 [166262], Section 6.3.2). The hydrogeologic subdivisions 
employed for the TSPA-LA are a synthesis of the Hydrogeologic Framework Model (HFM) 
(USGS 2003 [165176]) and the calibrated Site-Scale Saturated Zone Flow Model (BSC 2003 
[166262], Section 6.5.3). In all, there are 19 hydrogeologic units employed in the formulation of 
the base case SZ flow model (BSC 2003 [166262], Section 6.5.3.1), the base case transport 
model (Site-Scale Saturated Zone Transport, BSC 2003 [167208], Section 6.3), and the SZ flow 
and transport abstraction (SZ Flow and Transport Model Abstraction, BSC 2003 [167651], 
Section 6.3). 
The 19 hydrogeologic units can be grouped into five basic SZ hydrogeologic subdivisions: the 
upper volcanic aquifer, upper volcanic confining unit, lower volcanic aquifer, lower volcanic 
confining unit, and lower carbonate aquifer (BSC 2003 [166262], Section 6.3.2). In SZ base 
case flow model (BSC 2003 [166262], Sections 6.3.2 and 6.5.3.4), major discontinuities between 
the 19 hydrostratigraphic units are implemented by including 17 discrete features. These 
features reflect the degree of fracturing, faulting, fault orientation, and mineralogical alteration of 
glassy materials to zeolites and clay minerals. In the hydrogeologic units where flow and 
transport is expected to take place (the alluvium units and Units 15 through Units 11 for the 
volcanic units (BSC 2003 [166262], Section 6.6.2.2)), variability in transport properties between 
the major hydrogeologic units is implemented using a range of sampled parameters assigned to 
each unit for a particular realization (BSC 2003 [167651], Section 6.5.2). How the physical 
properties of stratigraphic units are modeled is discussed in FEP 2.2.03.02.0ARock properties 
of host rock and other units. Further discussions of the various aspects of stratigraphy affecting 
flow and transport in the SZ are found in BSC 2003 ([167651], Sections 6.5.2.1 and 6.5.2.2, and 
Table 6-3), and BSC 2003 ([167208], Section 6.3). 
6.2.15 Rock Properties of Host Rock and Other Units (2.2.03.02.0A) 
FEP Description: Physical properties such as porosity and permeability of the 
relevant rock units, soils, and alluvium are necessary for the 
performance assessment. Possible heterogeneities in these 
properties should be considered. Questions concerning events and 
processes that may cause these physical properties to change over 
time are considered in other FEPs. 
Descriptor Phrases: Rock properties in the SZ; Hydrologic properties in the SZ 
Screening Decision: Included 

Related FEPs: 1.2.02.01.0A, 1.2.02.02.0A, 2.2.03.01.0A, 2.2.07.12.0A, 
2.2.08.01.0A, 2.2.07.13.0A 
TSPA Disposition: 
Geologic features and heterogeneous hydrostratigraphic units are explicitly included in the SZ 
Transport Abstraction Model (SZ Flow and Transport Model Abstraction, BSC 2003 [167651], 
Section 6.2) as cells with specific hydrologic parameter values in a configuration based on the 
hydrogeologic framework used in the SZ Site-Scale Flow Model (BSC 2003 [166262], Section 
6.3.2). Spatial variability in rock properties is encompassed within uncertainty distributions for 
key parameters, such as groundwater specific discharge (GWSPD), horizontal anisotropy in 
volcanic units (HAVO), flowing interval spacing in volcanic units (FISVO), and sorption 
coefficients. Uncertainty in the location of the contact between alluvium and volcanic units at 
the southern end of the site-scale model is modeled probabilistically using the parameters related 
to the northern and western boundaries of the alluvial uncertainty zone, respectively (FPLAN 
and FPLAW). A more detailed description of the manner in which rock properties for specific 
hydrostratigraphic units are implemented is provided in the Supplemental Discussion for this 
FEP in this SZ FEP report. 
Supplemental Discussion: 
A base case permeability flow field is generated in the Site-Scale Saturated Zone Flow Model 
(BSC 2003 [166262], Section 6.5.3). Variability in permeability, due to the presence of faults 
and fractures, is accounted for in the base case flow model by incorporating 17 key 
heterogeneous features within the 19 modeled hydrostratigraphic units (BSC 2003 [166262], 
Sections 6.3.1 and 6.3.2). The presence of faults and fractures can either increase or decrease 
permeability within a unit. The SZ Transport Abstraction Model and the SZ 1-D Transport 
Model (both models described in BSC 2003 [167651], Section 6.5 and Table 6-2) take the base 
case flow model and incorporate additional uncertainty, heterogeneities, and potential changes in 
permeability through the stochastically sampled GWSPD (BSC 2003 [167651], Section 6.5.2.1). 
This results in multiple heterogeneous permeability fields. Additional uncertainty in 
permeability is accounted for in the SZ Transport Abstraction Model (BSC 2003 [167651], 
Section 6.5 and Table 6-2) through the following stochastically sampled parameters (1) 
horizontal anisotropy in the volcanic units (HAVO), (2) effective porosity in the alluvium units 7 
and 19 (NVF7 and NVF19), (3) flowing interval spacing (FISVO), (4) flowing interval porosity 
(FPVO) in the volcanics, (5) alluvium bulk density (bulk density), (6) sorption coefficients (Kdij) 
for the 9 radionuclides modeled in both the alluvium and volcanic units, and (7) longitudinal 
dispersivity (LDISP). The above parameters are described in Sections 6.5.2.3, 6.5.2.4, 6.5.2.5, 
6.5.2.7, 6.5.2.8, 6.5.2.9, and 6.5.2.10 of BSC 2003 ([167651]). 
The uncertainty in rock properties to be modeled along the alluvium-volcanic contact boundary 
is explicitly accounted for through the probabilistically sampled parameters, FPLAW and 
FPLAN (BSC 2003 [167651], Section 6.5.2.2), which define the western and northern 
boundaries, respectively, of the alluvium (valley-fill aquifer). These parameters determine 
whether alluvial or volcanic rock properties will be modeled within an area along the alluvial-
volcanic interface. 

There are numerous broad and distinct zones in the SZ flow model, categorized as features, 
which depend on their physical properties such as porosity and permeability. These zones act as 
either barriers or conduits to SZ groundwater flow and are directly or indirectly affected by 
faults, zones of mineralogical alteration along faults, or contact zones between units (BSC 2003 
[166262], Section 6.5.3.4, Table 12). These zones are (1) zones of permeability enhancement 
parallel to faults and zones of permeability reduction perpendicular to faults, (2) fault zones with 
enhanced permeability, (3) contact zones between units and non-fault zones, (4) faults 
representing regions of lower permeability caused by hydrothermal alteration, and (5) zones of 
unknown features. Details of the seventeen modeled features are given the FEP 2.2.07.13.0A
Water-conducting features in the SZ. 
6.2.16 Seismic Activity Changes Porosity and Permeability of Rock (2.2.06.01.0A) 
FEP Description: Seismic activity (fault displacement or vibratory ground motion) 
has a potential to change rock stresses and result in strains that 
affect flow properties in rock outside the excavation-disturbed 
zone. It could result in strains that alter the permeability in the 
rock matrix. These effects may decrease the transport times for 
potentially released radionuclides. 
Descriptor Phrases: Seismic activity (rock properties in the SZ) 
Related FEPs: 1.2.02.01.0A, 1.2.02.02.0A, 1.2.10.01.0A, 2.2.06.02.0A, 
2.2.06.02.0B, 2.2.10.05.0A 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
Plate tectonic activity has imparted crustal extension stresses within the Basin and Range 
Province (which includes the Yucca Mountain region) during the past 12 million years. The 
height of this activity occurred between 10 and 12 million years ago (m.y.a.) with estimated 
extension rates ranging between 10 and 30 mm/year (NRC 1992 [105162], Chapter 2). During 
this period major faults and fractures within the Yucca Mountain vicinity were created. 
Approximately 5 m.y.a. regional extension stresses declined to 5-10 mm/year; extension rates are 
still in a declining state today (NRC 1992 [105162], Chapter 2). On a local scale, regional 
extension rates impart local extension, compression and shear stresses on the crust depending on 
location, depths, and juxtaposition to parent rock units and existing faults. Release of stress 
results in seismic activities that create vibratory motion, faults (rupture), fault displacement, or 
areal redistribution of stresses not associated with specific faults. Vibratory stresses caused by 
seismic activity can alter the hydrologic properties of the parent rock. A seismic event can 
permanently affect rock hydrologic properties by (1) causing a change in pore pressures, which 
is usually a product of regional stress changes, or (2) an increase or decrease in permeability 
produced by either dilation, compression or breakage of granular structures produced from 
dynamic ground motion. 

A seismic event is most likely to cause movement along existing faults and fractures (BSC 2004 
[167720], Section 6.2.1.10) or change rock and inter-granular stresses, thus affecting rock 
hydrologic properties due to the creation of brecciation and gouge zones adjacent to the faults 
and existing fractures and possibly the production of new fractures (outside of the brecciated 
zone). This disturbed rock zone, labeled herein as a zone of alteration, is correlated with the 
amount of fault offsets (Sweetkind et al. 1997 [100183]). Faults with 15 m of cumulative offset 
have a zone of alteration width of only 12 m; faults with tens of meters of offset can have a 
zone of alteration tens of meters wide (Sweetkind et al. 1997 [100183], pp. 66 through 71). 
Existing rock hydrologic properties in the zone of alteration reflect the cumulative response to 
cumulative displacements of a dynamic seismic past, reflective of rapid extension rates in 
existent 10 to 12 m.y.a. and to a lesser extent, the lower extension rates in effect today. 
Expert elicitation, documented in the Probabilistic Seismic Hazard Analysis (PSHA) report, 
provides information that can be used to assess the effects of a seismic event on the hydrologic 
properties of intact rock. Of the numerous faults and seismic zones within vicinity of Yucca 
Mountain, the group identified nine regional and local fault displacement hazard zones they 
considered as most likely to contribute to maximum vibratory stresses (Probabilistic Seismic 
Hazard Analyses for Fault Displacement and Vibratory Ground Motion at Yucca Mountain, 
Nevada, CRWMS M&O 1998 [103731], Figure 4-9). 
One region of concern in the SZ flow domain is the area between Solitario Canyon and the Ghost 
Dance Faults, identified as Zone 8 by the PSHA group (CRWMS M&O 1998 [103731], Zone 8 
in Figure 4-9), which is due west of the source point for all SZ flow paths. In this region the 
PSHA group assessed the mean displacement for intact rock in the vicinity of the repository to be 
less than 0.1 cm for a 1E-08 annual-exceedance probability (CRWMS M&O 1998 [103731], 
Section 8). This area encompasses the same rock type as that along the origin of the Saturated 
Zone Flow and Transport (SZFT) paths. Therefore, it is inferred that future seismic activity will 
not result in any significant new faults and fractures in the intact rock, nor will it alter the 
hydrologic properties in the existing zone of alteration within that region that would affect SZ 
flow path origins. Flow path trajectories or flow velocities will not be significantly altered given 
predicted seismic activity within the area bounded by the Solitario Canyon and Ghost Dance 
Faults over the regulatory period. 
The PSHA panel estimated mean fault displacement for the majority of intrablock faults in the 
Yucca Mountain vicinity to be between 2 to 4 m at an annual exceedance probability of 1E-8 
(CRWMS M&O 1998 [103731], Section 8.2). The exceptions to this predicted range are the 
predicted displacements for the Solitario Canyon and Bow Ridge faults (CRWMS M&O 1998 
[103731], Zones 2 and 9 in Figure 4-9). The panel predicted approximately a 10-m mean fault 
displacement for the Solitario Canyon fault at an annual exceedance probability of 1E-8, and a 
7.5-m mean displacement for the Bow Ridge Fault at an annual exceedance probability of 1E-5 
(CRWMS M&O 1998 [103731], Figures 8-2 and 8-3). These displacements will not affect SZ 
transport and flow paths for the following reasons. 
The Solitario Canyon Fault has a cumulative displacement of approximately 260 m where it 
intersects the ECRB Cross-drift. With this relatively large displacement, its zone of alteration 

consists of approximately a 20-m brecciated and gouge zone and a seismically induced fractured 
area that extends tens of meters from the fault (BSC 2004 [167720], Section 6.2.1.10). The 10-m 
predicted displacement represents a fraction of the faults response to multiple seismic events 
imposed in the region for many millennia. It is inferred, given estimated future fault 
displacements inclusive of the approximately 10-m displacement for the Solitario Canyon fault, 
the hydrologic properties in the zone of alteration will not be significantly altered from current 
conditions in the next 10,000 years. Detailed discussions on the effects of seismic events on rock 
properties are provided in BSC (2004 [167720], Sections 6.2.1.8 through 6.2.1.11). 
The Bow Ridge fault is one of many faults included in the areally extensive faulted region 
identified as the Imbricate Fault Zone in the Site-Scale Saturated Zone Flow Model (BSC 2003 
[166262], Section 6.5.3.4 and Table 12). The Imbricate Fault Zone is modeled in a 
parallelogram shaped region encompassing an area approximately 3.5 km wide and 8 km long. 
It includes highly fractured and brecciation zones and numerous interconnected faults, the Bow 
Ridge Fault being one. Due to the higher incidence of interconnected fractures and faults located 
in this area, the SZ flow and transport model specifically incorporates relatively higher 
permeabilities here (BSC 2003 [166262], Section 6.4.3.2 and Figure 7). Because the Imbricate 
Fault Zone is areally extensive and includes numerous faults and their attendant zones of 
alteration, a 7.5-m fault displacement within the Bow Ridge fault would not alter the range of 
effective permeabilities attributed to this region. All other displacement hazard zones identified 
by the PHSA group are outside of the predicted SZ flow paths and thus will not affect SZ flow 
paths. 
An investigation conducted by the National Research Council (NRC 1992 [105162], Chapter 5 
referenced in DTN: MO0310INPDEFEP.000 [DIRS 165880]) looked at water table fluctuations 
given a predicted seismic event. Results from this report support the assumption that a future 
seismic event will not permanently alter the regional hydrologic properties of intact rock. The 
group looked at two modeling approaches in estimating the change in water table elevations 
given a seismically induced event: (1) a dislocation approach, where zones of extension on one 
side of a fault are balanced by compression across the fault, and (2) the more realistic changes in 
regional stress approach caused by normal fault slippage in regions of extension. The regional 
stress approach evaluates the effect of stress on pore pressure, which is dependent on the elastic 
properties of the bulk rock and the mineral grains. The extent of water table fluctuations differed 
for both models. Adopting the dislocation model, the water table rose approximately 10 m. 
Adopting the regional stress approach resulted in maximum water table rise of 50 m. The latter 
approach assumes realistically conservative rock and mineral elastic properties. The panel 
concluded, regardless of what approach is taken, the maximum water table rise given a seismic 
event would be less that 50 m and transient in nature. Because water table fluctuations were 
transient for both modeling approaches, it is inferred that a future seismic event (predicted over 
the next 10,000 years) will not permanently alter the rock hydrologic properties (including pore 
pressures) on a regional scale. 
Observations of water table responses to recorded seismic events support the above modeling 
results. The United States Geological Survey (USGS) has produced an Open File Report 93-73 
(OBrien 1993 [101276]), wherein water level fluctuations at Yucca Mountain due to 
earthquakes were analyzed. Fluctuations range from 90 cm related to a 7.5 magnitude 

earthquake near Landers, CA (approximately 420 km from Yucca Mountain), to 20 cm for a 
second quake of 6.6 magnitude near Big Bear Lake, CA (approximately 400 km from Yucca 
Mountain). More notably, a 5.6 magnitude quake at Little Skull Mountain (approximately 23 km 
from Yucca Mountain) resulted in a maximum fluctuation of 40 cm, with water levels in another 
well declining approximately 50 cm over the 3 days following the earthquake. Water levels in 
that well returned to pre-quake levels over a period of about 6 months. Implicit in the 
observations, given the short duration and relatively small magnitude of seismically induced 
water table fluctuations, was that a seismically induced permanent change in regional rock 
hydrologic properties from the observed earthquakes did not occur. 
As stated earlier, existing rock hydrologic properties along a faults zone of alteration reflect the 
cumulative response to cumulative displacements of a dynamic seismic past. Because the Yucca 
Mountain region is now experiencing lower extension rates and is tectonically less active, 
predicted fault displacements are minor and will alter rock properties minimally compared to 
intact rock alterations due to the cumulative fault displacements of an active tectonic past. 
Furthermore, flow and transport in the SZ is dominated by existing fractures, fracture clusters 
and fracture spacing, collectively labeled as flowing intervals in the SZFT model (BSC 2003 
[167651], Section 6.3). The SZFT model evaluates uncertainties assigned to flowing interval 
properties such as horizontal anisotropy in the volcanic units, flowing interval spacing, flowing 
interval porosity in the volcanics, and longitudinal dispersion (SZ Flow and Transport Model 
Abstraction, BSC 2003 [167651], Table 6-8). Transport times through the SZ are quite sensitive 
to parameter uncertainty associated with flowing interval properties (only uncertainty in the 
specific discharge scaling parameter, which is meant to account for increased specific discharge 
due to a wetter climate, produces a greater variation in transport times). As an example, 
parameter uncertainty in flowing interval spacing results in transport times that vary by several 
thousands of years (Arnold et al. 2000 [166335]). The uncertainty incorporated in the horizontal 
anisotropy (which accounts for the uncertainty in maximum and minimum in-situ stresses 
imposed on fractures and faults) results in transport paths varying by several kilometers (BSC 
2003 [167651], Figure 6-6). Thus the incorporated parameter uncertainty in regional flowing 
interval properties overwhelms any changes in SZ transport times and flow paths associated with 
seismically induced changes in hydrologic properties of the rock matrix inclusive of the Bow 
Ridge fault in the Imbricate Fault Zone and the Solitario Canyon fault (see related FEPs 
1.2.10.01.0AHydrologic response to seismic activity, 2.2.06.02.0ASeismic activity changes 
porosity and permeability of faults, and 2.2.06.02.0BSeismic activity changes porosity and 
permeability of fractures). 
In summary, the expected changes in rock properties due to seismic activity are excluded based 
on low consequence because they will not significantly change radiological exposures to the 
RMEI or radionuclide releases to the accessible environment. 
6.2.17 Seismic Activity Changes Porosity and Permeability of Faults (2.2.06.02.0A) 
FEP Description: Seismic activity (fault displacement or vibratory ground motion) 
has a potential to produce jointed-rock motion and change stress 
and strains that alter the permeability along faults. This could 
result in reactivation of preexisting faults or generate new faults 

and significantly change the flow and transport paths, alter or 
short-circuit the flow paths and flow distributions close to the 
repository and create new pathways through the repository. These 
effects may decrease the transport times for potentially released 
radionuclides. 
Descriptor Phrases: Seismic activity (faults in the SZ) 
Screening Decision: ExcludedLow consequence 
Related FEPs: 1.2.02.01.0A, 1.2.02.02.0A, 1.2.10.01.0A, 2.2.06.01.0A, 
2.2.06.02.0B, 2.2.10.05.0A 
Screening Argument: 
Fault displacement is a result of regional plate tectonic activity that imparts crustal extension 
stresses causing rupture of the parent rock. Within the Basin and Range Province (which 
includes the Yucca Mountain region) peak extension stresses occurred between 10 and 12 
million years ago (m.y.a.) with extension rates between 10 and 30 mm/year (NRC 1992 
[105162], Chapter 2). These rapid extension rates formed two major north trending extension 
belts and normal faulting zones. Approximately 5 m.y.a. regional extensional stress declined to 
510 mm/year; extension rates are still in a declining state today (NRC 1992 [105162], Chapter 
2). It is the extension stresses imposed on the areally broad Basin and Range Province that 
impart the extension, compression and shear stresses on the crust and determine fault 
development. The type of stress transmitted locally is dependent on location, depth, and 
juxtaposition to existing faults. These locally imposed stresses, which control existing fault 
hydrological properties (Site-Scale Saturated Zone Flow Model, BSC 2003 [166262], Section 
6.3.2.10), are driven by the crustal (and now declining) extension rates. Of interest is the 
likelihood of future fault formation and displacement within the Yucca Mountain region. 
Expert elicitation, documented in the Probabilistic Seismic Hazard Analysis (PSHA) report, 
provides information that can be used to assess the effects of a seismic event on fault formation. 
The PSHA group assessed the mean displacement in intact rock to be less than the 0.1 cm for a 
1E-08 annual-exceedance probability. Consequently, no significant new faults are likely to form 
in the Yucca Mountain vicinity within the next 10,000 years. 
A seismic event is most likely to cause movement along existing faults and could affect a faults 
hydrologic properties. With the exception of the Solitario Canyon fault, the PSHA panel 
estimated mean fault displacement for the majority of intra-block faults in the Yucca Mountain 
vicinity to be between 2 to 4 m at an annual exceedance probability of 1E-8 (Probabilistic 
Seismic Hazard Analyses for Fault Displacement and Vibratory Ground Motion at Yucca 
Mountain, Nevada, CRWMS M&O 1998 [103731], Section 8.2). At the same low exceedance 
probability the panel predicted a 10-m mean fault displacement the for Solitario Canyon fault 
(CRWMS M&O 1998 [103731], Figure 8-3). As discussed in Errata for Features, Events and 
Processes: Disruptive Events (BSC 2004 [167720], Section 6.2.1.10), the energy produced from 
a seismic event will be dissipated along existing faults. This energy can cause deformation and 
breakage of the parent rock creating brecciation and gouge zones adjacent to the faults and 

existing fractures and possibly the production of new fractures (outside of the brecciated zone). 
This disturbed rock zone, labeled herein as a zone of alteration, is correlated with the amount 
of fault offset (Sweetkind et al. 1997 [100183]). Generally, the zone of alteration adjacent to the 
fault is relatively narrow. Faults with 15 m of cumulative offset have a zone of alteration width 
of only 12 m; faults with tens of meters of offset can have zone of alteration up to tens of 
meters wide (Sweetkind et al. 1997 [100183], pp. 66 through 71). 
Several studies have been performed to determine changes in water table elevations due to 
seismic induced changes in fault properties, implicitly due to fault offset. Carrigan et al. 1991 
[100967] modeled a 100-m wide fracture zone centered on a vertical fault (i.e., a seismically 
induced altered zone) such that vertical permeability was increased by three orders of magnitude. 
The results of that model indicate (a short-term) transient water table rise of up to 12 m in the 
fracture zone with 1 m of fault slip. Their tectonohydrologic model simulated earthquakes 
typical of the Basin and Range Province (with approximately a 1-m slip) to produce a simulated 
rise of 2 m to 3 m for a water table 500 m below ground surface. Extrapolation to a 4-m slip 
results in a transient rise of 17 m near the fault (Carrigan et al. 1991 [100967], p. 1159). 
Gauthier et al. (1996 [100447], pp. 163 through 164) analyzed the potential changes in water 
table elevation due to the effects of seismic activity as a result of three different types of fault 
displacements. For all three fault types, a 1-m displacement with a 30-km rupture length was 
considered. Simulations of the timing, magnitude, and duration of water table rise indicate a 
maximum rise of 50 m within an hour of the simulated event. The simulated system returns to 
steady-state conditions within 6 months. Gauthier et al. 1996 [100447] concluded that: 
In general, seismically induced water table excursions caused by poroelastic 
coupling would not influence the models presently being used to determine long-
term performance of a repository at Yucca Mountain; therefore, we excluded 
them from the total-system simulation. 
The above studies predict short-term water table excursion given 1-m to 4-m fault slips. It is 
inferred that an approximately 10-m displacement along the Solitario Canyon fault will result in 
transient and slightly higher water table excursions. These early studies substantiate an 
investigation headed by the National Research Council (NRC 1992 [105162]) on the geologic 
and climatic processes that could affect water elevations. The council addressed the maximum 
level the water table could rise within the next 10,000 years given several processes, one being 
seismic pumping. They evaluated water table responses due to two types of seismic processes: 
(1) dislocation, where zones of extension on one side of a fault are balanced by compression 
across the fault; and (2) the more realistic changes in regional stress approach caused by 
normal fault slippage in regions of extension. The regional stress approach evaluates the effect 
of stress on pore pressure, which is dependent on the elastic properties of the bulk rock and the 
mineral grains. The extent of water table fluctuations differed for both models. Adopting the 
dislocation model, the water table rose approximately 10 m. Adopting the regional stress 
approach resulted in maximum water table rise of 50 m. The later approach assumes realistically 
conservative rock and mineral elastic properties. The panel concluded, regardless of what 
approach is taken, the maximum water table rise given a seismic event would be less that 50 m 
and transient in nature. Because water table fluctuations were transient for both modeling 
approaches, it is inferred that a future seismic event (predicted over the next 10,000 years) that 

could result in a 10-m slip along the Solitario Canyon fault will not alter the faults hydrologic 
properties. 
Moreover, current Solitario Canyon fault hydrologic properties reflect the cumulative effects of a 
highly active tectonic and seismic past that resulted in a 260-m cumulative fault displacement 
where it intersects the ECRB Cross-drift (Mongano et al. 1999 [149850], pp. 48-65). With this 
relatively large fault displacement, its zone of alteration consists of approximately a 20-m 
brecciated and gouge zone and seismically induced fractured area that extends tens of meters 
from the fault (BSC 2004 [167720], Section 6.2.1.10). An approximately 10-m displacement of 
the Solitario Canyon fault (and other faults) will release local stresses accumulated along the 
fault plane but will not alter the large and globally extensive stresses in effect over the past 10 to 
12 million years, incurred in the parent rock and embedded faults within the Yucca Mountain 
region (NRC 1992 [105162], Chapter 5 referenced in DTN: MO0310INPDEFEP.000 
[DIRS 165880]). It is these global and areally extensive stresses imposed on the fault that 
determine the faults hydrologic properties. It is logically concluded the Solitario Canyon faults 
hydrologic properties will be remain essentially unchanged given an approximately 10-m 
displacement. The fault will continue to serve as a groundwater divide between the Yucca 
Mountain and the Crater Flat regions (Site-Scale Saturated Zone Flow Model, BSC 2003 
[166262], Section 6.3.2). As observed with other fault displacements, the water table could rise 
or decrease due to seismic response, but the fluctuation will be (at most) a few tens of meters and 
transient in nature. 
The magnitude and transient nature of a predicted water table rise is consistent with observation 
of recorded seismic events. The United States Geological Survey (USGS) has produced an Open 
File Report 93-73 (OBrien 1993 [101276]) wherein water table level fluctuations at Yucca 
Mountain due to earthquakes are analyzed. Water table fluctuations range from 90 cm, related to 
a 7.5 magnitude earthquake near Landers, CA (approximately 420 km from Yucca Mountain), to 
20 cm for a second quake of 6.6 magnitude near Big Bear Lake, CA (approximately 400 km 
from Yucca Mountain). More notably, a 5.6 magnitude quake at Little Skull Mountain 
(approximately 23 km from Yucca Mountain) resulted in a maximum fluctuation of 40 cm, with 
water levels in another well declining approximately 50 cm over the 3 days following the 
earthquake. Water levels in that well returned to pre-quake levels over a period of about 6 
months. The above reports support the fact that recorded fault slippage in the Yucca Mountain 
region has resulted in a transient hydrologic response but has not resulted in permanent alteration 
of the faults regional hydrologic properties. 
Additionally, the uncertainty in the effective hydrologic properties incorporated in the SZ flow 
and transport model (SZ Flow and Transport Model Abstraction, BSC 2003 [167651], Table 
6-8), which reflects the cumulative changes in a faults hydrologic properties during a heightened 
seismically active past, coupled with the scale of the model (a grid discretized 500 m in the 
horizontal direction and 10 to 550 m in the vertical direction), overwhelms the changes in fault 
properties that would be caused by seismic events within the next 10,000 years. Flow and 
transport in the SZ is dominated by existing fractures, fracture clusters and fracture spacing, 
collectively labeled as flowing intervals in the Saturated Zone Flow and Transport (SZFT) model 
(BSC 2003 [167651], Section 6.3). The SZFT model evaluates uncertainties assigned to flowing 
interval properties such as horizontal anisotropy in the volcanic units, flowing interval spacing, 

flowing interval porosity in the volcanics, and longitudinal dispersion (BSC 2003 [167651], 
Table 6-8). Transport times through the SZ are quite sensitive to parameter uncertainty 
associated with flowing interval properties (only uncertainty in the specific discharge scaling 
parameter, which is meant to account for increased specific discharge due to a wetter climate, 
produces a greater variation in transport times). As an example, parameter uncertainty for 
flowing interval spacing results in transport times that vary by several thousands of years 
(Arnold et al. 2000 [166335]). The uncertainty incorporated in the horizontal anisotropy (which 
accounts for the uncertainty in maximum and minimum in-situ stresses imposed on fractures and 
faults) results in transport paths varying by several kilometers (BSC 2003 [167651], Figure 6-6). 
Thus the incorporated parameter uncertainty in regional flowing interval properties overwhelms 
any potential changes in a faults hydrologic properties associated with future seismic activity 
(and is reflective of regional tectonic activity). 
Consequently, future seismic events will not alter the range of existing fault permeability and 
porosity values incorporated in the SZ flow and transport model (See related FEPs 1.2.10.01.0A
Hydrologic response to seismic activity and 2.2.06.02.0BSeismic activity changes porosity and 
permeability of fractures). 
In summary, seismic events will have a minimal effect on the simulated flux at the compliance 
boundary and on the release of radionuclides to the accessible environment based on the 
following conclusions: 
1. The energy of future seismic events will be primarily transmitted through existing 
fractures and faults, rather than development of new ones. 
2. Changes to fault properties (which implicitly affect the faults hydrologic properties) will 
tend to occur in a relatively narrow zone, and be on the order of a few meters to, at most, 
tens of meters wide along the length of the fault (BSC 2004 [167720], Section 6.2.1.10). 
3. Current fault porosities and permeabilities reflect the effects of a seismically active past 
within the Yucca Mountain region. Past seismic activity is reflective of major plate 
extension and caldera formation phases in the Basin and Range Province, which includes 
the Yucca Mountain region. Seismic activity within the Yucca Mountain region is 
currently in a relatively quiescent period. Consequently, seismic events that will occur 
in the next 10,000 years will have a relatively low impact on existing fault 
hydrologic properties. 
4. The uncertainty in the effective hydrologic properties incorporated in the SZ flow and 
transport model, coupled with the flux multiplier that effectively models wetter climatic 
conditions, overwhelms the changes that would be caused by small movements along 
existing faults. 
5. Observed, seismically-induced water table fluctuations, and those simulated with 
numerical models, indicate future seismic events will alter water table elevations for a 
relatively short period of time. After a seismic event, water table elevations will return to 
pre-existing levels within about a 6-month period. 

In conclusion, changes in fault properties in the SZ can be excluded based on low consequence 
because they will not significantly affect radiological exposures to the RMEI or radionuclide 
releases to the accessible environment. 
6.2.18 Seismic Activity Changes Porosity and Permeability of Fractures (2.2.06.02.0B) 
FEP Description Seismic activity (fault displacement or vibratory ground motion) 
has a potential to change stress and strains that alter the 
permeability along fractures. This could result in reactivation of 
preexisting fractures or generation of new fractures. Generation of 
new fractures and reactivation of preexisting fractures may 
significantly change the flow and transport paths, alter or short-
circuit the flow paths and flow distributions close to the repository, 
and create new pathways through the repository. These effects 
may decrease the transport times for potentially released 
radionuclides. 
Descriptor Phrases: Seismic activity (fractures in the SZ) 
Related FEPs: 1.2.02.01.0A, 1.2.02.02.0A, 1.2.10.01.0A, 2.2.06.01.0A, 
2.2.06.02.0A, 2.2.10.04.0A 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
Fault displacement, and concomitant fracture formation, is a result of regional plate tectonic 
activity that imparts crustal extension stresses causing rupture of the parent rock. Within the 
Basin and Range Province (which includes the Yucca Mountain region) peak extension stresses 
were 1030 mm/year between 10 and 12 million years ago (m.y.a.) (NRC 1992 [105162], 
Chapter 2). These rapid extension rates formed two major north trending extension belts and 
normal faulting zones. Approximately 5 m.y.a. regional extensional stress declined to 510 
mm/year; extension rates are still in a declining state today (NRC 1992 [105162], Chapter 2). It 
is the extension stresses imposed on the areally broad Basin and Range Province that imparts the 
extension, compression and shear stresses on the crust and determine fault and concomitant 
fracture development and properties. The type of stress transmitted locally is dependent on 
location, depths, and juxtaposition to existing faults. These locally imposed stresses, which 
control existing fault hydrological properties (Site-Scale Saturated Zone Flow Model, BSC 2003 
[166262], Section 6.3.2.10), are driven by the crustal (and now declining) extension rates. 
Concurrent with declining extension rates are declining fault and fracture development and fault 
displacement. Of interest is the likelihood of fracture formation within the Yucca Mountain 
region. 
Expert elicitation documented in the Probabilistic Seismic Hazard Analysis (PSHA) report 
predict less than a 1-cm displacement within the vicinity of the repository host rock (between 

Solitario Canyon and the Ghost Dance Faults) at a 1E-08 exceedance probability (Probabilistic 
Seismic Hazard Analyses for Fault Displacement and Vibratory Ground Motion at Yucca 
Mountain, Nevada, CRWMS M&O 1998 [103731], Section 8). Consequently, no significant 
new faults and fractures are likely to form in the Yucca Mountain vicinity within the next 10,000 
years. Furthermore, future seismic events are most likely to cause movement along existing 
faults and fractures. With the exception of the Solitario Canyon fault, the PSHA panel estimated 
mean fault displacement for the majority of intra-block faults in the Yucca Mountain vicinity to 
be between 2 to 4 m at an annual exceedance probability of 1E-8 (CRWMS M&O 1998 
[103731], Section 8.2). At the same low exceedance probability the panel predicted a 10-m 
mean fault displacement for the Solitario Canyon fault (CRWMS M&O 1998 [103731], Figure 
8-3). As discussed in Errata for Features, Events and Processes: Disruptive Events (BSC 2004 
[167720], Section 6.2.1.10), the energy produced from a seismic event will be dissipated along 
existing faults. Changes in rock properties along the length of existing faults, due to the creation 
of brecciation and gouge zones adjacent to the fault and the production of fractures (outside of 
brecciated zone), are correlated with the amount of fault offsets (Sweetkind et al. 1997 
[100183]). Generally, the zone of alteration adjacent to the fault (which includes fractures) is 
relatively narrow. Faults with 15 m of cumulative offset have a zone of alteration width of only 
12 m; faults with tens of meters of offset can have zone of alteration up to tens of meters wide 
(Sweetkind et al. 1997 [100183], pp. 66 through 71). The Solitario Canyon Fault has a 
cumulative displacement of approximately 260 m where it intersects the ECRB Cross-drift; with 
this relatively large displacement its zone of alteration consists of approximately a 20-m 
brecciated and gouge zone and seismically induced fractures that extend tens of meters from the 
fault (BSC 2004 [167720], Section 6.2.1.10). 
Several studies have been performed to determine changes in water table elevations due to 
seismically induced changes in fault and fracture properties. Carrigan et al. (1991 [100967]) 
modeled a 100-m wide fracture zone centered on a vertical fault, such that vertical permeability 
was increased by three orders of magnitude. The results of that model indicate a transient water 
table rise of up to 12 m in the fracture zone with one meter of slip. These results indicate seismic 
pumping due to changes in fracture permeability along faults would produce a short-term and 
transient water table rise. 
The above study predicts short-term water table excursion given 1- to 4-m fault slips and 
attendant alteration of adjacent fractures. It is inferred that an approximately 10-m displacement 
along the Solitario Canyon fault, and resulting changes in fracture properties, will result in 
transient and slightly higher water table excursions. This assumption is supported by an 
investigation headed by the National Research Council on the geologic and climatic processes 
that could affect water elevations. The council addressed the maximum level the water table 
could rise within the next 10,000 years given several processes, one being seismic pumping. 
They evaluated water table responses due to two types of seismic processes: (1) dislocation, 
where zones of extension on one side of a fault are balanced by compression across the fault; and 
(2) the more realistic changes in regional stress approach caused by normal fault slippage in 
regions of extension. The regional stress approach evaluates the effect of stress on pore pressure, 
which is dependent on the elastic properties of the bulk rock and the mineral grains. The extent 
of water table fluctuations differed for both models. Adopting the dislocation model, the water 
table rose approximately 10 m. Adopting the regional stress approach resulted in maximum 

water table rise of 50 m. The later approach assumes realistically conservative rock and mineral 
elastic properties. The panel concluded that regardless of what approach is taken, the maximum 
water table rise given a seismic event would be less that 50 m and transient in nature. Because 
water table fluctuations were transient for both modeling approaches, it is inferred that a future 
seismic event (predicted over the next 10,000 years) that could result in changes in the regional 
stress field imposed on fractures, inclusive of a stresses imposed by a 10-m slip along the 
Solitario Canyon fault, will not alter the regional fracture hydrologic properties. 
The magnitude and transient nature of a predicted water table rise is consistent with observation 
of recorded seismic events. The United States Geological Survey (USGS) has produced an Open 
File Report 93-73 (OBrien 1993 [101276]), wherein water table level fluctuations at Yucca 
Mountain due to earthquakes are analyzed. Water table fluctuations range from 90 cm, related to 
a 7.5 magnitude earthquake near Landers, CA (approximately 420 km from Yucca Mountain), to 
20 cm for a second quake of 6.6 magnitude near Big Bear Lake, CA (approximately 400 km 
from Yucca Mountain). More notably, a 5.6 magnitude quake at Little Skull Mountain 
(approximately 23 km from Yucca Mountain) resulted in a maximum fluctuation of 40 cm, with 
water levels in another well declining approximately 50 cm over the 3 days following the 
earthquake. Water levels in that well returned to pre-quake levels over a period of about 6 
months. The above reports support the fact that recorded seismic events in the Yucca Mountain 
region resulted in a transient hydrologic response. Given the observed transient responses to 
seismic events within the southwest portion of the Basin and Range province, it is inferred that 
the above seismic events did not alter regional fracture hydrologic properties. 
Additionally, flow and transport in the SZ is dominated by existing fractures, fracture clusters 
and fracture spacing, collectively labeled as flowing intervals in the Saturated Zone Flow and 
Transport (SZFT) model (SZ Flow and Transport Model Abstraction, BSC 2003 [167651], 
Section 6.3). The SZFT model evaluates uncertainties assigned to flowing interval properties 
such as horizontal anisotropy in the volcanic units, flowing interval spacing, flowing interval 
porosity in the volcanics, and longitudinal dispersion (BSC 2003 [167651], Table 6-8). 
Transport times through the SZ are quite sensitive to parameter uncertainty associated with 
flowing interval properties (only uncertainty in the specific discharge scaling parameter, which is 
meant to account for increased specific discharge due to a wetter climate, produces a greater 
variation in transport times). As an example, parameter uncertainty in flowing interval spacing 
results in transport times that vary by several thousands of years (Arnold et al. 2000 [166335]). 
The uncertainty incorporated in the horizontal anisotropy (which accounts for the uncertainty in 
maximum and minimum in-situ stresses imposed on fractures and faults) results in transport 
paths varying by several kilometers (BSC 2003 [167651, Figure 6-6). Thus the incorporated 
parameter uncertainty in regional flowing interval properties overwhelms any changes in SZ 
transport times and flows paths associated with seismically induced changes in flowing interval 
properties. 
Furthermore, existing regional stresses imposed on fracture hydrologic properties reflect the 
crustal extension stresses in effect today. A fractures physical properties (orientation, length, 
connectivity and clustering) are reflective of a cumulative response to seismic events in existence 
10 to 12 million years ago. A change in regional fracture properties, given predicted seismic 
activity, will be minimal relative to multiple seismic events imposed in the region for many 

millennia. Therefore, it is inferred, regional fracture hydrologic properties will not be 
significantly altered from current conditions in the next 10,000 years. As a result changes in 
intact fracture properties are excluded based on low consequence because they will not 
significantly affect radiological exposures to the RMEI or radionuclide releases to the accessible 
environment. 
(Additional discussions on the effects of seismic events on rock properties are provided in BSC 
2004 [167720], Sections 6.2.1.8, 6.2.1.9, 6.2.1.10, and 6.2.1.11.) 
6.2.19 Saturated Groundwater Flow in the Geosphere (2.2.07.12.0A) 
FEP Description: Groundwater flow in the saturated zone below the water table may 
affect long-term performance of the repository. The location, 
magnitude, and direction of flow under present and future 
conditions and the hydraulic properties of the rock are all relevant. 
Descriptor Phrases: Saturated flow and pathways in the SZ 
Related FEPs: 1.4.07.02.0A, 2.2.03.01.0A, 2.2.03.02.0A, 2.2.07.13.0A, 
2.2.07.16.0A, 2.2.07.15.0A, 2.2.12.00.0B 
Screening Decision: Included 
TSPA Disposition: 
Steady-state, saturated, 3-D groundwater flow within the Yucca Mountain vicinity is modeled 
through the Site-Scale Saturated Zone Flow Model (BSC 2003 [166262], Sections 6.2 and 6.3.1) 
using the numerical code FEHM V 2.20 (LANL 2003 [161725], STN: 10086-2.20-00). The 
model domain is a 30- by 45-km region within the confines of the Death Valley groundwater 
basin (BSC 2003 [166262], Section 6.3.2). Inputs include faults and fault zones (BSC 2003 
[166262], Section 6.3.2.10) and variable permeabilities associated with the 19 hydrostratigraphic 
units (FEP 2.2.03.02.0ARock properties of host rock and other units) identified through the 
Hydrogeologic Framework Model (USGS 2003 [165176]). The most significant flow units are 
the volcanic Crater Flat Tuff hydrogeologic (hydraulic) units and the shallow alluvial aquifer of 
Fortymile Wash. Flow through fractures is modeled through an effective continuum flow model 
(BSC 2003 [166262], Section 6.3.3). 
Recharge is modeled through underflow, surface flow infiltration, and UZ infiltration 
components (BSC 2003 [166262], Section 6.3.2.7). The impact of future climatic conditions on 
flow are modeled in the SZ Flow and Transport Model Abstraction (BSC 2003 [167651], Section 
6.5) using a convolution integral method (SZ_Convolute V 2.2 software code (STN: 10207-2.2-
00, Sandia National Laboratories (SNL) 2003 [163344]) and BSC 2003 [167651], Section 6.5) 
that scales radionuclide breakthrough curve simulations representing current climatic conditions 
using representative scaling factors (BSC 2003 [167651], Section 6.5.1). 

6.2.20 Water-Conducting Features in the SZ (2.2.07.13.0A) 
FEP Description: Geologic features in the saturated zone may affect groundwater 
flow by providing preferred pathways for flow. 
Descriptor Phrases: Fracture flow in the SZ 
Screening Decision: Included 
Related FEPs: 1.2.02.01.0A, 1.2.02.02.0A, 2.2.03.01.0A, 2.2.03.02.0A, 
2.2.07.12.0A, 2.2.12.00.0A, 2.2.12.00.0B 
TSPA Disposition: 
Faults and fractures in the volcanic units are explicitly modeled in the SZ (SZ Flow and 
Transport Model Abstraction, BSC 2003 [167651], Section 6.2) through 17 discrete geologic 
features incorporated in the SZ base case model (Site-Scale Saturated Zone Flow Model, BSC 
2003 [166262], Section 6.3.2). The variability and uncertainty due to the presence of fracture 
clusters, flowing intervals, and rubblized zones (all possible subsets of water-conducting features 
within the faulted and fractured system) is modeled in the SZ Transport Abstraction Model and 
the SZ 1-D Transport Model (both described in BSC 2003 [167651], Section 6.5.2 and Table 6-
2) through the following stochastically sampled parameters: (1) groundwater specific discharge 
(GWSPD), (2) the flowing interval parameter (FISVO), (3) horizontal anisotropy in the volcanic 
units (HAVO), (4) flowing interval porosity in the volcanics (FPVO), and (5) longitudinal 
dispersivity (LDISP). The ranges of uncertainty in these parameters encompass the possibility of 
channelized flow along preferred pathways. The above parameters are described in Sections 
6.5.2.1, 6.5.2.4, 6.5.2.5, 6.5.2.9, and 6.5.2.10 of BSC 2003 [167651]. 
There are numerous broad and distinct zones in the SZ flow model, categorized as features 
and, depending on their physical properties, act as either barriers or conduits to SZ groundwater 
flow. These are areas directly or indirectly affected by faults, zones of mineralogical alteration 
along faults, or contact zones between units (BSC 2003 [166262], Section 6.5.3.4). A more 
detailed description of the modeling of water conducting features in the SZ is provided in the 
Supplemental Discussion for this FEP in this SZ FEP report. 
Supplemental Discussion: 
There are numerous broad and distinct zones in the SZ flow model, categorized as features, 
which act as either barriers or conduits to SZ groundwater flow. These are areas directly or 
indirectly affected by faults, zones of mineralogical alteration along faults, or contact zones 
between units (BSC 2003 [166262], Section 6.5.3.4). A feature with no known association with 
distinct fault or fault zones is also incorporated into the Saturated Zone Flow and Transport 
(SZFT) model and is based on a large hydraulic gradient, which exists just north and slightly 
west of Yucca Mountain. There are several theories as to what is the cause of the large hydraulic 
gradient, but no one theory is overwhelmingly favored over others. Nevertheless, a feature (with 

no geologic significance) has been incorporated into the model to produce a large hydraulic 
gradient north of the repository. 
All 17 features are distinct from the sub-horizontal geologic formations in which they reside; 
most are essentially vertical, with some linear in the horizontal extent, and others areally 
extensive (BSC 2003 [166262], Figure 19). Depending on their hydrologic impact on 
groundwater flow patterns, these features fall under several distinct categories. A list of the 17 
features modeled in the Site-Scale Saturated Zone Flow Model (BSC 2003 [166262], Table 12), 
aggregated under hydrologic categories, is given below. Figure 6.2-3 is a depiction of the 
seventeen discrete features modeled in the SZFT model; many of these features are based on 
known faults and fault zones depicted on the left side of the figure. 
(1) Zones of permeability enhancement parallel to faults and zones of permeability 
reduction perpendicular to faults 
 Crater Flat FaultThis is a linear feature running north-south in the western half of 
the model, starting south of Claims Canyon and terminating near Highway 195, 
almost halfway between the western boundary of the Solitario Canyon. Vertically, it 
extends from the top to the bottom of the model. 
 Solitario Canyon Fault ZoneA north-south trending linear feature just to the west 
of Yucca Mountain. Vertically it extends from the top to the bottom of the model. 
 Solitario Canyon Fault, East BranchA north-northeast trending linear feature just 
to the west of Yucca Mountain. Vertically, it extends from the bottom of the model 
to the top of the model. 
 Solitario Canyon Fault, West BranchA north-northeast trending linear features 
just to the west of Yucca Mountain. Vertically, it extends from the bottom of the 
model to the top of the model. 
 Highway 95 Fault (West)This is a linear feature in the lower half of the western 
portion of the model. It is east-southeast trending. Vertically, it extends from the 
bottom to the top of the model. 
(2) Fault zones with enhanced permeability 
 Bare Mountain FaultThis is a northwest- to southeast-trending linear feature in the 
southwestern corner of the model. Vertically, it extends from the bottom to the top of 
the model. 
 Imbricate Fault ZoneThis is a highly faulted area bounded in the west by the Ghost 
Dance fault, south by the Dune Wash, east by the Paintbrush Canyon fault, and to the 
north by the Drillhole Wash. Vertically, it extends from the top of the model down 
through the middle volcanics to the top of the undifferentiated units. 
(3) Contact zones between units and non-fault zones 
 Alluvial Uncertainty ZoneThis feature represents the uncertainty zone between the 
alluvium and tuff boundaries. It is roughly a rectangular region to the south of Yucca 
Mountain in the southern half of the model. Vertically, it extends from the top of the 
model down through the undifferentiated units. 

 Spotted Range-Mine Mountain ZoneThis triangular feature is in the southeast 
corner of the model. Vertically, it extends from top of the model down to the bottom. 
A zone of enhanced permeability is associated with the Spotted Range Thrust Region. 
 Fortymile Wash ZonesThese two north-south linear features are located 
approximately halfway between Yucca Mountain and the eastern model boundary. 
Vertically, it extends from the top to the bottom of the model. 
 Lower Fortymile Wash ZoneThis quadrilateral, enhanced permeability feature 
encompasses the Lower Fortymile Wash part of the model. The depth of the zone 
includes the alluvium unit to the top of the model. 
(4) Faults representing regions of lower permeability caused by hydrothermal 
alteration 
 Northern Zone (entire Claim Canyon, Calico Hills, and Shoshone Mt.)This zone 
is wedge-shaped, spanning almost the entire northern boundary (except the western 
corner of the northern boundary) and approximately the upper fourth of the eastern 
boundary. Vertically, it extends from the top to the bottom of the model. 
 Northern Crater Flat ZoneThis wedge-shaped zone is at the northern third of the 
western boundary of the model. Vertically, it extends from the top to the bottom of 
the model. 
 Claim Canyon CalderaThese zones span much of the northern boundary of the 
model, extending south as triangular shapes and terminating north of the Yucca 
Wash. Vertically, it extends from the top to the bottom of the model. 
 Shoshone Mt. ZoneThese two zones are in the northeastern corner of the model. 
They extend from the top of the carbonate aquifer up to the top of the model. 
Vertically, it extends from the top to the bottom of the model. 
 Calico Hills ZoneThese two zones are near the eastern end of the model, south of 
the Shoshone Mountain Zones, at approximately the same northing as the Yucca 
Wash. Vertically, it extends from the top to the bottom of the model. 
(5) Zones of unknown features 
 East-West BarrierThis linear feature runs east-west just to the north of Yucca 
Mountain, starting at the western edge of Yucca Mountain and extending eastwards 
short of the Calico Hills. Vertically, it extends from the bottom to the top of the 
model. It is a permeability reduction zone. 

Figure 6.2-3. Geologic Features in the Area of the Site-Scale Flow Model (from BSC 2003 
[166262], Figure 19) 
Text Box: from BSC 2003 [166262] Figure 19 
DTN: GS010908314221.001 (left panel) Output DTN: LA0304TM831231.002 (right panel).
NOTE: Field data are on the left panel, and the SZ model representation is on the right panel. Numbers designate the following regions: 45 - Lower FortyMile Wash Zone; 56 - East-West Barrier Zone; 57 and 58 - Fortymile Wash Zones; 59 - Spotted Range-Mine Mountain Zone; 61 and 62 - Claim Canyon Caldera Zones; 63 and 64 - Shoshone Mountain Zones; 65 and 66 - Calico Hills Zones; 69, 70, 71, and 72 - Crater Flat Fault Zones; 74, 83, and 84 - Solitario Canyon Fault Zones; 75 and 76 - Solitario Canyon Fault Zones (East Branch); 77 and 78 - Solitario Canyon Fault Zones (West Branch); 79 - Highway 95 Fault Zone; 80 and 90 - Bare Mountain Fault Zones; 81 - Northern Zone; 82 - Northern Crater Flat Zone; 88 - Alluvial Uncertainty Zone (expected case); 91 - Imbricate Fault Zone.

6.2.21 Chemically-Induced Density Effects on Groundwater Flow (2.2.07.14.0A) 
FEP Description: Chemically induced spatial variation in groundwater density may 
affect groundwater flow. 
Descriptor Phrases: Density-driven flow in the SZ 
Screening Decision: ExcludedLow consequence 
Related FEPs: 2.2.08.01.0A, 2.2.10.04.0A, 2.2.10.08.0A, 2.2.10.13.0A, 
2.2.11.01.0A, 2.2.12.00.0B 
Screening Argument: 
The FEP is based on the bounding and imposed condition that a contaminant plume reaches the 
water table with the signature of the repository (i.e., relatively higher temperature and different 
solute concentrations than the groundwater at the water table). Buoyancy effects, coupled with 
density gradients, would cause the plume to flow along the water table surface, relatively 
unmixed, for a considerable distance. Density gradients tend to spread the plume laterally. 
These effects would all tend to hinder contaminant and radionuclide transport to the accessible 
environment. Consequently, the potential dose to the hypothetical and exposed community is 
overestimated rather than underestimated. 
The TSPA-LA models calculate the concentration of contaminants in groundwater by capturing 
all the contaminants that cross the regulatory boundary in the wells at the compliance point. No 
credit is taken for partial plume capture due to density-driven flow effects. The mixing model 
assumes that pumping and re-distribution of well water will be far greater than any other energy 
gradients (e.g., thermal, chemical, and gravitational) that exist in the groundwater system. There 
is no modeled groundwater flow component resulting from buoyancy effects, or differences in 
the groundwater density due to the presence or absence of contaminants. The TSPA approach to 
dose modeling is predicated on the use of a prescribed volume of water. As long as that 
prescribed volume of water is defensible and consistent with regulations, by assuming that all the 
particles that cross the regulatory boundary are dissolved in the prescribed volume of water 
(3,000 acre-feet per year, per guidance given in 10 CFR Part 63 Subpart 63.332(3) [156605]), the 
potential dose to the hypothetical, exposed community will not be underestimated. Including 
this FEP into the TSPA-LA calculations would be beneficial to repository performance. Given 
that the volume of extracted water consumed is independent of density and thermal gradients, 
and all the contaminants that cross the regulatory boundary are contained in that volume of 
water, the potential dose to the hypothetical and exposed community is overestimated rather than 
underestimated. Therefore, this FEP is excluded based on low consequence because it has no 
adverse effects on performance. 
6.2.22 Advection and Dispersion in the SZ (2.2.07.15.0A) 
FEP Description: Advection and dispersion processes may affect contaminant 
transport in the saturated zone. 

Descriptor Phrases: Advection of dissolved radionuclides in the SZ; Dispersion of 
dissolved radionuclides in the SZ 
Related FEPs: 2.2.07.12.0A, 2.2.07.16.0A, 2.2.07.17.0A, 2.2.08.08.0A, 
2.2.08.10.0A 
Screening Decision: Included 
TSPA Disposition: 
Advection and longitudinal dispersion of dissolved radionuclides are explicitly included in the 
conceptual and mathematical models for TSPA-LA (Site-Scale Saturated Zone Transport, BSC 
2003 [167208], Sections 6.2, 6.3 and 6.5). The numerical code FEHM (V 2.20 STN: 10086-2.0-
00, LANL 2003 [161725]) implements dispersion tensor and random walk particle tracking 
method. The flow field and the dispersion tensor input to this model are dependent on the nature 
of the geologic material and the scale of the model. 
FEHM V 2.20 (STN: 10086-2.20-00, LANL 2003 [161725]) generates a mean 3-D specific 
discharge (advection) flow field using calibrated permeability as input. The mean specific 
discharge field is output from the Site-Scale Saturated Zone Flow Model (BSC 2003 [166262], 
Section 6.6.2.2). The mean calibrated permeability field is scaled with the stochastically 
sampled scaling parameters for groundwater-specific discharge (GWSPD) and the horizontal 
anisotropy in volcanic units (HAVO) (SZ Flow and Transport Model Abstraction, BSC 2003 
[167651], Sections 6.5.2.1 and 6.5.2.10) to produce 200 unique 3-D permeability fields. 
GWSPD scales permeabilities in both the volcanic and alluvium units. The range for the 
GWSPD scaling parameter is based on field-test analyses (discussed in Saturated Zone In-Situ 
Testing, BSC 2003 [167209]), calibration of the mean flow field to measured heads (discussed 
in BSC 2003 [166262], Section 6.5.3), and expert elicitation (discussed in Saturated Zone Flow 
and Transport Expert Elicitation Project, CRWMS M&O 1998 [100353], Section 3.2). The 
HAVO parameter determines the degree of anisotropy in permeability for only the volcanic 
units. HAVO is based on field-test analyses discussed in BSC 2003 [167209] and numerical 
analysis discussed in BSC 2003 [166262], Section 6.5.3. Detailed discussions of the scaling 
parameters GWSPD and HAVO implementation are located in BSC 2003 ([167651], Sections 
6.5.2.1 and 6.5.2.10). 
Uncertainty in the dispersion tensor is modeled by stochastically varying the input longitudinal 
dispersivity value. This approach is done using the longitudinal dispersion parameter (LDISP) 
(BSC 2003 [167651], Section 6.5.2.9). The range for the LDISP parameter is based on 
recommendations from the expert elicitation panel (CRWMS M&O 1998 [100353], Section 3.2), 
which were used as the basis for determining the bounds on the longitudinal dispersivity. 
The transverse and vertical dispersion parameters are less than longitudinal dispersivity, not 
varied independently, and scaled based on the stochastically sampled LDISP value input to each 
flow field. Further discussions on transverse and vertical dispersion are located in BSC 2003 
([167651], Section 6.5.2.9). 

6.2.23 Dilution of Radionuclides in Groundwater (2.2.07.16.0A) 
FEP Description: Dilution due to mixing of contaminated and uncontaminated water 
may affect radionuclide concentrations in groundwater during 
transport in the saturated zone and during pumping at a 
withdrawal well. 
Descriptor Phrases: Radionuclide dilution (in groundwater) 
Screening Decision: Included 
Related FEPs: 1.4.07.02.0A, 2.2.07.12.0A, 2.2.07.15.0A, 2.2.08.09.0A, 
3.2.07.01.0A 
TSPA Disposition: 
Dilution of radionuclides as a result of pumping is included in the TSPA-LA in two ways (SZ 
Flow and Transport Model Abstraction, BSC 2003 [167651], Section 6.2). First, dilution of 
simulated radionuclide concentrations within the contaminant plume is explicitly modeled 
through the transverse hydrodynamic dispersion parameter. Transverse dispersivity is a function 
of the stochastically sampled longitudinal dispersivity parameter (LDISP) (BSC 2003 [167651], 
Sections 6.7.2 and 6.5.2.9). Secondly, it is assumed in BSC 2003 ([167651], Section 6.7.2) that 
all the radionuclide mass crossing the 18-km regulatory boundary is captured by the pumping 
well of the hypothetical farming community. The volume of water (per guidance given in 
10 CFR Part 63 Subpart 63.332, (3) [156605]) pumped from the hypothetical farming 
community is 3,000 acre-feet per year (about 3.7 x 109 liters), which is larger than the volumetric 
flow of contaminated groundwater crossing the 18-km boundary. Therefore, the degree of 
dilution is the ratio of the flux of contaminated groundwater to volume of water pumped by the 
hypothetical farming community. 
6.2.24 Diffusion in the SZ (2.2.07.17.0A) 
FEP Description: Molecular diffusion processes may affect radionuclide transport in 
the SZ. 
Descriptor Phrases: Diffusion of dissolved radionuclides in the SZ 
Screening Decision: Included 
Related FEPs: 2.2.08.08.0A, 2.2.07.15.0A 
TSPA Disposition: 
This FEP addresses diffusive transport (e.g., fracture diffusion) such as is modeled numerically 
as part of the hydrodynamic dispersion coefficient (part mechanical dispersion, part diffusion). 
Matrix diffusion (which contributes to retardation) is addressed in the FEP 2.2.08.08.0AMatrix 

diffusion in the SZ. The dispersion tensor appearing in Equation 1 (Site-Scale Saturated 
Zone Transport, BSC 2003 [167208]) is the sum of the mechanical dispersion tensor () for the 
flow system and the coefficient of molecular diffusion () in porous media. Together, these 
processes are modeled using the stochastically sampled longitudinal dispersivity parameter 
(LDISP) (BSC 2003 [167651], Sections 6.7.2 and 6.5.2.9) and the transverse hydrodynamic 
dispersion parameter, which is a function of LDISP. The effects of molecular diffusion are 
explicitly included also in the displacement matrix given by Equation 55 in the SZ Transport 
Abstraction Model (BSC 2003 [167208]). The effects of molecular diffusion are thus explicitly 
included in the SZ transport model. These effects are significant only at low flow velocities 
(Bear 1972 [156269], p. 581). The specific discharge value of 0.67 m/year reported in Site-Scale 
Saturated Zone Flow Model (BSC 2003 [166262], Section 6.6.2.3) leads to fluid velocities on the 
order of 10-7 to 10-4 m/s. Combining this with the lower limit of the longitudinal dispersivity of 
0.1 m given in Table 4-2 of BSC 2003 [167208], this leads to a lower limit of dispersion 
coefficient in excess of 10-8 m2/s. The upper limit of effective diffusion coefficient for volcanics 
given in Table 4-2 (BSC 2003 [167208]) is 5x10-10 m2/s. Thus, the effects of molecular 
diffusion, which are included in the SZ flow and transport models (BSC 2003 [167208], Section 
6.2) are overshadowed by advection and dispersion. 
6.2.25 Chemical Characteristics of Groundwater in the SZ (2.2.08.01.0A) 
FEP Description: Chemistry and other characteristics of groundwater in the saturated 
zone may affect groundwater flow and radionuclide transport of 
dissolved and colloidal species. Groundwater chemistry and other 
characteristics, including temperature, pH, Eh, ionic strength, and 
major ionic concentrations, may vary spatially throughout the 
system as a result of different rock mineralogy. 
Descriptor Phrases: Initial THC characteristics in the SZ (temperature, pH, Eh, water 
conc., gas conc., ionic strength); Spatially dependent chemical 
effects on sorption in the SZ 
Screening Decision: Included 
Related FEPs: 2.2.07.14.0A, 3.2.07.01.0A, 2.2.10.08.0A, 2.2.09.01.0A, 
2.2.10.04.0A, 3.1.01.01.0A, 2.2.08.09.0A, 2.2.08.07.0A, 
2.2.08.06.0A, 1.2.09.02.0A, 2.2.03.01.0A, 2.2.03.02.0A, 
2.2.08.03.0A 
TSPA Disposition: 
Variations in temperature, pH, Eh, ionic strength, and major ionic concentrations in the 
groundwater affect sorption of radionuclides onto the rock surface and colloids, which in turn, 
affects the sorption coefficient, Kd, and thus, the retardation factor, Rf, for each radionuclide. In 
the Site-Scale Saturated Zone Transport model (BSC 2003 [167208], Sections 6.2 and 
6.5.2.4.1), these coefficients are entered directly in the transport base case model that describes 
radionuclide transport via the distribution coefficients and the retardation factors (BSC 2003 

[167208], Equations 56 and 57), which describe reactive transport through porous media. The 
effects of THC and dissolved gases within the SZ are implicitly included in the variations in 
temperature, pH, Eh, ionic strength, and major ionic concentrations in the groundwater. 
Appropriate ranges and distributions of values for Kds are chosen based on expert elicitation 
(Saturated Zone Flow and Transport Expert Elicitation Project, CRWMS M&O 1998 [100353], 
Section 3.2) and laboratory and field studies for the sorption coefficient Kd (BSC 2003 [167208], 
Attachment I). The parameter ranges are incorporated in the model abstraction through the Kd 
variables KDNPVO, KDRAVO, KDSRVO, KDUVO, KDNPAL, KDRAAL, KDSRAL, 
KDUAL, KD_AM_VO, KD_CS_VO, KD_PU_VO, KD_AM_AL, KD_CS_AL, KD_PU_AL, 
the colloid retardation factor in the alluvium (CORAL), and the colloid retardation factor in 
volcanic units (CORVO) (SZ Flow and Transport Model Abstraction, BSC 2003 [167651], 
Sections 6.5.2.8 and 6.5.2.11). 
Regarding the spatial and temporal dependencies of Kd, geochemical analysis indicates that 
current SZ groundwater under the proposed repository and along the SZ transport path is 
paleoclimate recharge water (Geochemical and Isotopic Constraints on Groundwater Flow 
Directions and Magnitudes, Mixing, and Recharge at Yucca Mountain, Nevada, BSC 2003 
[167211], Section 7.1.2). Spatial variability in the composition of the ground water reflects, in 
part, temporal variability in recharge when data from the Forty Mile Wash are included. 
Uncorrected 14C ground water ages range from a few thousand years in vicinity of the Forty Mile 
Wash to values greater than 15,000 years under portions of the Yucca Mountain (BSC 2003 
[167211], Tables 10 and 11). Using the reasonable approach that spatial variability within the 
recharge domain brackets the temporal variability expected to occur at a given location within 
the domain, the observed variability in geochemistry among the wells in the model area brackets 
the temporal variations expected to occur in the water composition. Additionally, significant 
water table rise is evidenced to have occurred under paleoclimatic conditions (Site-Scale 
Saturated Zone Flow Model, BSC 2003 [166262], Section 6.4.5.1 and BSC 2003 [167208], 
Attachment V). Thus, the water quality of sampled paleoclimate recharge water reflects past 
interactions with rock types overlying the current water table as well as the rock types along the 
expected transport pathways. Consequently, the range in each radionuclide Kd and effective 
colloidal retardation factor bracket the temporal variations in water composition given volume 
and time of recharge, as well as the variability in pH, Eh, mineralogy, and the number of rock 
sorption sites. 
. 

6.2.26 Geochemical Interactions and Evolution in the SZ (2.2.08.03.0A) 
FEP Description: Groundwater chemistry and other characteristics, including 
temperature, pH, Eh, ionic strength, and major ionic 
concentrations, may change through time, as a result of the 
evolution of the disposal system or from mixing with other waters. 
Geochemical interactions may lead to dissolution and precipitation 
of minerals along the groundwater flow path, affecting 
groundwater flow, rock properties and sorption of contaminants. 
Effects on hydrologic flow properties of the rock, radionuclide 
solubilities, sorption processes, and colloidal transport are relevant. 
Kinetics of chemical reactions should be considered in the context 
of the time scale of concern. 
Descriptor Phrases: Time-dependent THC characteristics in the SZ (temperature, pH, 
Eh, water conc., gas conc., ionic strength); Time-dependent 
chemical effects on sorption in the SZ; Effects of 
precipitation/dissolution in the SZ; Effects of weathering in the SZ 
Screening Decision: ExcludedLow consequence 
Related FEPs: 1.2.06.00.0A, 1.2.09.02.0A, 2.2.08.01.0A, 2.2.08.06.0A, 
2.2.08.07.0A, 2.2.08.09.0A, 2.2.08.10.0A, 2.2.09.01.0A, 
3.2.07.01.0A 
Screening Argument: 
Geochemical analysis indicates current SZ groundwater under the repository and along the SZ 
transport path is paleoclimate recharge water (Geochemical and Isotopic Constraints on 
Groundwater Flow Directions and Magnitudes, Mixing, and Recharge at Yucca Mountain, 
Nevada, BSC 2003 [167211], Section 7.1.2). The paleoclimate recharge water currently 
undergoes rock-water interactions in the UZ and SZ and in the past has mixed with waters from 
flow systems having different recharge waters than those indicative of current dry climatic 
conditions. These waters are reflective of cooler climatic conditions and cooler recharge waters 
10,000 to 16,000 years old (BSC 2003 [167211], Section 6.3). Cooler water is able to dissolve 
more oxygen and thus has a higher oxidation state than warmer water (i.e., the temperature 
dependency of Henrys Law). Compared to recharge waters reflective of current climatic 
conditions, paleoclimate recharge waters have higher carbon contents and higher concentrations 
of dissolved CO2 gas, which also contributes to higher oxidation states (Eh potential) and a lower 
pH. Lower pHs and higher CO2 concentrations equate to waters that are more aggressive and 
will participate in more dissolution and subsequent precipitation along the transport path 
compared to groundwaters originating from current climatic conditions. Consequently, resident 
SZ water chemistry currently encountered along the SZ transport path reflects the maximum 
time-dependent variability in pH and CO2 gas concentrations. As a result, current geochemical 
conditions, used to derive the range in each radionuclide Kd and effective colloidal retardation 
factor, bracket the temporal variations in water chemistry given the volume and time of recharge, 

as well as the variability in pH, Eh, mineralogy, and the number of rock sorption sites (specific 
details pertaining to variability in Eh are discussed the Supplemental Discussion). Therefore, 
temporal changes in water geochemistry are excluded based on low consequence. 
Regional Yucca Mountain SZ recharge waters mainly occur through direct infiltration through 
the UZ and not through surface water recharge (such as lakes and perennial rivers). 
Consequently, temporal changes in surface water quantities are excluded based on low 
consequence. Since hydrothermal activity is considered to be low consequence to regional SZ 
flow and flow paths in the Yucca Mountain vicinity (see FEP 1.2.06.00.0AHydrothermal 
activity), temporal geochemical changes due to an increase in geothermal (hydrothermal) activity 
will not affect SZ geochemistry and are therefore excluded based on low consequence. 
Detailed discussions pertaining to related FEPs in groundwater chemistry as it effects transport 
and sorption are addressed by FEPs 2.2.08.01.0AChemical characteristics of groundwater in the 
SZ, 2.2.08.06.0AComplexation in the SZ; 2.2.08.07.0ARadionuclide solubility limits in the 
SZ; 2.2.08.09.0ASorption in SZ; 2.2.08.10.0AColloid transport in the SZ; and the following 
analysis and model reports: Geochemical and Isotopic Constraints on Groundwater Flow 
Directions and Magnitudes, Mixing, and Recharge at Yucca Mountain, Nevada (BSC 2003 
[167211], Section 6.7); Saturated Zone Colloid Transport (BSC 2003 [162729], Section 6.2); 
and Site-Scale Saturated Zone Transport (BSC (2003 [167208], Attachments I, II, III, and IV). 
All of the above reasoned arguments support the conclusion that geochemical interactions and 
evolution is excluded based on low consequence to radiological exposures to the RMEI. A more 
detailed discussion of future geochemical interactions and evolution in the SZ is provided in the 
Supplemental Discussion for this FEP in this SZ FEP report. 
Supplemental Discussion: 
For the TSPA-LA transport model (BSC 2003 [167208]), it is assumed that the SZ groundwaters 
along the transport path are oxidizing from the UZ/SZ interface to the 18-km compliance 
boundary. However, there is evidence of localized reducing zones along the SZ transport 
pathway that may result in the reduction of redox sensitive radionuclides such as Np, Pu, Tc, and 
U. These radionuclides are less soluble at lower oxidation states (i.e., reducing environments) 
and could precipitate out of solution and accumulate in localized reduction zones. A subsequent 
return to oxidizing conditions within the localized reduction zones during the regulatory 
timeframe would favor dissolution of these precipitates back into solution, causing groundwater 
concentrations to increase to levels above those that were in effect prior to reaching these 
reduction zones. 
It is not likely the local reduction zones will be oxidized during the regulatory period, nor will 
they increase in size. A large-scale change in oxidation state from that seen currently at 
Yucca Mountain is excluded on low probability and regulatory grounds. The rationale for this 
statement is as follows: 
1. Reducing conditions were found in boreholes USW H-1, USW H-4, and UE-25b#1 
(Ogard and Kerrisk 1984 [100783], Section IV, and USW WT-17 (BSC 2003 [167208], 
Table 4-1). The reducing agents for groundwater in these wells could be located in the 

groundwater itself or in the rock matrix. Since the reducing zones are local in extent, the 
aquifer matrix most likely supplies most of the reduction capacity. Generally, in volcanic 
rocks the reduction capacity is associated with solid sulfides (e.g., pyrite), biotite, and 
other ferrous iron-bearing minerals. Although data points are sparse, pyrite (a reducing 
agent) is found deep in borehole USW H-3 in the Tram member of the Crater Flat tuff 
(Thordarson et al. 1984 [103200]). Predicted radionuclide flow paths are focused 
primarily in the Prow Pass and Bullfrog units (Site-Scale Saturated Zone Flow Model, 
BSC 2003 [166262], Section 6.2.4.4). Therefore, most, if not all, of the predicted 
plumes flow path will pass through oxidized, and not reduced, zones. On this basis, 
potential changes in localized oxidation states in the SZ are excluded on 
low consequence. 
2. The high iron contents measured in groundwater from USW WT-17 suggest that the 
parent rock may contain some reducing agents. However, the well history, coupled with 
its high organic concentrations and low Eh measurements, indicate Eh measurements 
from this well may not be reflective of the rocks in-situ redox conditions. Groundwater 
chemistry pumped from borehole USW WT-17 in 1998 was unique from other wells in 
the area. Groundwater from this well shows reducing characteristics (Eh < 0.0 mv), little 
or no dissolved oxygen and nitrate, and high organic carbon (up to 20 mg/L, 
DTN: GS980908312322.008 [145412]). One possible explanation for this unique 
combination is well contamination. This well was originally drilled to assess water table 
elevations and not as a pump test well. Consequently, it was not developed after well 
completion. It is possible drilling fluid, containing organic materials, had migrated from 
the borehole down gradient and was eventually withdrawn during the subsequent 
pumping event performed several years after initial drilling. This scenario would explain 
the low Eh, high organic carbon concentrations, and the low dissolved oxygen and nitrate 
concentrations. The above indicates Eh measurements in borehole USW WT-17 are 
suspect and do not conclusively support that reducing conditions exist in the vicinity of 
this borehole. 
3. An alternative explanation for the reducing conditions in borehole WT-17 is that the site 
is located above a source of hydrocarbons in the deeper SZ (i.e., the Paleozoic aquifer). 
However, Yucca Mountain is considered to be an area with low hydrocarbon potential 
(French 2000 [107425], p. 7-11) and no hydrocarbon activity. Because regulations 
dictate present socio-economic practices are reflective of future practices (Section 63.305 
[156605]), hydrocarbon exploration that could potentially produce a large reduction zone 
are not included as part of the TSPA-LA model. 
4. Resident groundwaters along the projected groundwater flow path are reflective of cooler 
climatic conditions and cooler recharge waters 10,000 to 16,000 years old (BSC 2003 
[167211], Section 6.3). Cooler water is able to dissolve more oxygen and thus has a 
higher oxidation state than warmer water (i.e., the temperature dependency of Henrys 
Law). Compared to recharge waters reflective of current climatic conditions, 
paleoclimate recharge waters have higher carbon contents and higher CO2 concentrations, 
which also contributes to higher oxidation states and a lower pH. The above conditions 
promote more dissolution and subsequent precipitation than that of groundwaters 

originating from current climatic conditions. Consequently, the capability of future 
groundwaters, reflective of the current climate pulse, to further oxidize localized reducing 
zones within the next 10,000 years is not a credible mechanism. 
5. There is no current mechanism known to support that reducing conditions will be more 
extensive along the flow path than what is currently seen. The total reduction capacities 
in the parent rock are a function of the concentration of the rocks in-situ reducing agents 
and the volume of these reducing zones. To date, only localized reduction zones have 
been produced over the past several million years. It is reasonable to presume that this 
reduction capacity will remain localized over the relatively short 10,000-year regulatory 
time frame. Therefore, a significant increase in the size of these local reduction zones is 
not credible. 
Furthermore, the reduction capacity of the parent rock has persisted over several million 
years. As it has over the past several million years, the reduction capacity will continue 
to persist, and not be depleted, over the relatively short 10,000-year regulatory time 
frame. Therefore, a significant switch between reducing to oxidizing conditions in these 
local reduction zones is not likely to occur within the next 10,000 years. 
6.2.27 Complexation in the SZ (2.2.08.06.0A) 
FEP Description: Complexing agents such as humic and fulvic acids present in 
natural groundwaters could affect radionuclide transport in the SZ. 
Descriptor Phrases: Complexation in the SZ 
Screening Decision: Included 
Related FEPs: 1.2.09.02.0A, 2.2.08.01.0A, 2.2.08.03.0A, 2.2.08.07.0A, 
2.2.09.01.0A, 3.2.07.01.0A, 2.2.08.09.0A 
TSPA Disposition: 
Complexing agents are included in the TSPA-LA (Site-Scale Saturated Zone Transport, BSC 
2003 [167208], Sections 6.3 and 6.5). In the SZ inorganic complexing agents, such as 
carbonates are dominant, whereas organic complexing agents, such as humic and fulvic acids, 
are not found in significant amounts (see FEP 2.2.09.01.0A  Microbial activity in the SZ). 
Complexing agents can affect sorption of radionuclides onto the rock surface and colloids. The 
sorption coefficients Kd and Kc enter via Equations 56, 57, 76, 77, and 78 in BSC 2003 
([167208], Sections 6.5.2.4.1 and 6.5.2.5), which describe reactive transport through porous 
media. These effects are included in the model by choosing appropriate ranges of values for the 
sorption coefficients Kd and Kc as described in BSC 2003 [167208], Attachments I and II, 
respectively. Available data are summarized in the BSC (2003 [167208], Table 6.2-2); Kd and 
Kc distributions are developed on the basis of these data. 

6.2.28 Radionuclide Solubility Limits in the SZ (2.2.08.07.0A) 
FEP Description: Solubility limits for radionuclides may be different in saturated 
zone groundwater than in the water in the unsaturated zone or in 
the waste and EBS. 
Descriptor Phrases: Radionuclide solubility (concentration) limits in the SZ 
Screening Decision: ExcludedLow consequence 
Related FEPs: 2.2.08.01.0A, 2.2.08.03.0A, 2.2.08.06.0A, 2.2.08.09.0A 
2.2.08.10.0A, 2.2.10.04.0A, 2.2.10.08.0A, 3.1.01.01.0A, 
3.2.07.01.0A 
Screening Argument: 
The SZ Flow and Transport Model Abstraction (SZ Flow and Transport Model Abstraction, BSC 
2003 [167651]) does not implement a solubility limit for each transported radionuclide, thus 
allowing the radionuclide solution concentration that is introduced into SZ from the UZ to be 
unconstrained. The rationale supporting this position is as follows. Solubility determines the 
maximum concentration a constituent can reach in the aqueous phase solution; therefore it is 
considered a bounding property. Once a particular radionuclide reaches that maximum 
concentration or solubility limit, it will form a precipitate or solid. The solid can be either a pure 
radionuclide-bearing solid or a solid solution of two (or more) end-members. The radionuclide 
constituent will then be in secular equilibrium between the solid and aqueous phase. The 
precipitate forming solid phase will increase in mass until the concentration in the solution phase 
falls below the solubility limit. Once this happens, the solid phase will then dissolve into the 
aqueous phase. Thus, if a solubility limit were to be imposed into the SZ model that is lower 
than that implemented in the Dissolved Concentration Limits of Radioactive Elements (BSC 
2001 [154431], Section 6.5), it would cause precipitates to form, pulling constituents out of the 
aqueous phase and reducing the maximum aqueous concentration capable of being transported 
downstream to the compliance boundary. Additionally, physical build-up of a solid phase onto 
mineral surfaces (due to precipitation not adsorption) can reduce permeability, increase 
tortuosity, and clog pores, thus increasing transport times. 
In summary, introduction of a solubility limit in the SZ would be beneficial to performance. 
Therefore, this FEP is excluded based on low consequence because not imposing a solubility 
limit in the model has no adverse effects on performance. 
6.2.29 Matrix Diffusion in the SZ (2.2.08.08.0A) 
FEP Description: Matrix diffusion is the process by which radionuclides and other 
species transported in the SZ by advective flow in fractures or 
other pathways move into the matrix of the porous rock by 
diffusion. Matrix diffusion can be a very efficient retarding 

mechanism, especially for strongly sorbed radionuclides due to the 
increase in rock surface accessible to sorption. 
Descriptor Phrases: Matrix diffusion in the SZ 
Screening Decision: Included 
Related FEPs: 2.2.07.15.0A, 2.2.07.17.0A 
TSPA Disposition: 
Matrix diffusion is the process by which radionuclides transported in the SZ move into the 
matrix of the porous rock. This process can be a very effective retarding mechanism and is 
explicitly included in the conceptual model of transport in the mathematical model transport 
Equations 56 and 57, Section 6.5.2.4.1 (Site-Scale Saturated Zone Transport, BSC 2003 
[167208]), and in the numerical implementation of the model FEHM (V 2.20 STN: 10086-2.0-00 
[161725]) through the use of the diffusion coefficient and the random-walk particle-tracking 
method with a semi-analytical solution. 
Matrix diffusion is included in the SZ transport model abstraction (SZ Flow and Transport 
Model Abstraction, BSC 2003 [167651], Table 6.8) through the matrix diffusion parameter 
diffusion coefficient in volcanics (DCVO). The semianalytical matrix diffusion equation obeys 
Ficks law and incorporates concentration gradients and the temporal and spatial changes in the 
gradient along the transport pathway. Matrix diffusion is modeled only in the matrix portion of 
the volcanic units (BSC 2003 [167651], Section 6.5.2.6). The cumulative distribution function 
(CDF) for the DVCO is based on: 
 field and laboratory diffusion experiments performed in and on volcanic tuffs located 
within the Yucca Mountain vicinity 
 a least-squares linear empirical equation fit to diffusion experiment results and measured 
values for matrix porosity and permeability. 
The effective matrix diffusion coefficients for diffusing radionuclides are stochastically sampled 
from this same CDF. 
Given the inhomogeneous nature of the alluvium, flow could preferentially occur through high-
permeability regions, and matrix diffusion could potentially occur into the low permeability 
regions of the alluvium. Data is available only from single-hole tracer tests conducted at the 
Alluvial Testing Complex (ATC) (Saturated Zone In-Situ Testing, BSC 2003 [167209], Section 
6.5.4, Figures 6.5-18 through 6.5-20). Based on this available data, as a conservative approach 
no credit is taken for matrix diffusion into low-permeability regions within the alluvium. 
Similarly, no credit is taken for matrix diffusion of colloids in either the volcanics or the 
alluvium, because the effects would be small and would only retard transport. 

6.2.30 Sorption in the SZ (2.2.08.09.0A) 
FEP Description: Sorption of dissolved and colloidal radionuclides in the SZ can 
occur on the surfaces of both fractures and matrix in rock or soil 
along the transport path. Sorption may be reversible or 
irreversible, and it may occur as a linear or nonlinear process. 
Sorption kinetics and the availability of sites for sorption should be 
considered. Sorption is a function of the radioelement type, 
mineral type, and groundwater composition. 
Descriptor Phrases: Sorption of dissolved radionuclides in the SZ; Sorption of colloids 
in the SZ 
Screening Decision: Included 
Related FEPs: 2.2.07.16.0A, 2.2.08.01.0A, 2.2.08.03.0A, 2.2.08.06.0A, 
2.2.08.07.0A, 2.2.08.10.0A, 2.2.10.08.0A 
TSPA Disposition: 
Sorption of radionuclides onto rock surfaces can occur both in the volcanic rocks and the 
alluvium (Site-Scale Saturated Zone Transport, BSC 2003 [167208], Attachment I). This 
process is modeled through a suite of partitioning coefficients Kds (SZ Flow and Transport 
Model Abstraction, BSC 2003 [167651], Section 6.5.2.8) for the radionuclides Am, Cs, Np, Pa, 
Pu, Ra, Th, and U (BSC 2003 [167208], Attachment I). In the volcanic rocks, sorption in the 
matrix is explicitly included in the retardation coefficient Rf in Equations 56b and 57 (BSC 2003 
[167208], Section 6.5.2.4.1). Sorption within individual fractures is not included in the 
conceptual model as an extreme case; however, sorption can occur within flowing zones due to 
the rubblized matrix, and this effect is included in the retardation coefficient R in Equation 56a. 
Sorption in the alluvium is described in Equation 77 in the Site-Scale Saturated Zone Transport 
(BSC 2003 [167208]). 
Radionuclides modeled as entrained irreversible colloids in Waste Form and In-Drift Colloids-
Associated Radionuclide Concentrations: Abstraction and Summary (BSC 2003 [166845], 
Sections 6.2 and 6.3.1) are sorbed as well. The alluvium is largely composed of disaggregated 
tuffaceous material, mixed with clays and other secondary minerals. Each developed 
radionuclide Kd distribution brackets the regional variability in Kd values due to variations in pH, 
Eh, water composition (representative of J-13 and UE-25 p#1 waters), mineralogy, and the 
number of rock sorption sites. Additionally, Kd distributions encompass the potential nonlinear 
behavior of the sorption processes, thus accounting for sorption kinetics (BSC 2003 [167208], 
Attachment I). 
The volcanic units are primarily composed of zeolitic and devitrified tuffaceous materials. The 
alluvium is largely composed of disaggregated tuffaceous material, mixed with clays and other 
secondary minerals. Because radionuclides have a greater sorption affinity onto clays and 
secondary minerals than tuffaceous materials, alluvium Kd values are slightly higher than those 

for the volcanic units (BSC 2003 [167208], Attachment I) and are reflected as such in alluvium 
Kd distributions. Table I-4 in BSC 2003 [167208] summarizes SZ sorption model parameters. 
Sorption of Dissolved Radionuclides: In the volcanic units, Np, Ra, Sr, and U sorption between 
the aqueous phase and the solid phase (parent rock) is modeled in the FEHM flow and transport 
code using the sampled parameters KDNPVO, KDRAVO, KDSRVO, KDUVO, respectively 
(BSC 2003 [167651], Section 6.5.2.8); sorption for the same radionuclides in the alluvium is 
modeled through the parameters KDNPAL, KDRAAL, KDSRAL, and KDUAL. 
Sorption of Reversible Colloids: Equilibrium sorption between aqueous and solid phases and a 
colloidal phase is modeled for the radionuclides Am, Cs, Pa, Pu, and Th (BSC 2003 [167208], 
Attachment I). The sampled parameters Kd_Pu_Col and Kd_Cs_Col model Pu and Cs 
partitioning between the aqueous and colloidal phases, respectively. Partitioning between the 
aqueous and colloidal phase for the radionuclides Am, Th, and Pa is modeled through the 
sampled parameter Kd_Am_Col. Partitioning between the colloidal and aqueous phase is the 
same in both the volcanics and the alluvium. Partitioning between the aqueous and solid phase 
(parent rock) for each species differs between the volcanic and alluvial units. In the volcanic 
units, Pu and Cs aqueous- and solid-phase partitioning is modeled through the sampled 
parameters Kd_Pu_Vo and Kd_Cs_Vo, respectively. For Am, Th, and Pa, the same partitioning 
is modeled through the single sampled parameter Kd_Am_Vo. In the alluvium, Pu and Cs 
partitioning between aqueous and solid phases is modeled with the sampled parameters 
Kd_Pu_Al, Kd_Cs_Al; for Am, Pa, and Th, it is modeled through the parameter Kd_Am_Al 
(BSC 2003 [167651], Section 6.5.2.12.) 
Sorption of Irreversible Colloids: In the volcanic units, the dispersed advectively transported 
Pu and Am colloids (Saturated Zone Colloidal Transport, BSC 2003 [162729], Section 6.4 and 
BSC 2003 [166845], Section 6.3.3.2) sorb onto fracture surfaces through a colloid retardation 
factor CORVO (BSC 2003 [167651], Section 6.5.2.11). In the alluvium, these same colloids are 
effectively sorbed via a sampled retardation factor CORAL (BSC 2003 [167651], Section 
6.5.2.11). 
Table 6.2-2 summarizes which radionuclides have sorption coefficients (Kd) assigned to them, 
their parameter name, whether they are sorbed reversibly or irreversibly to the parent rock, 
colloids, or both (i.e., in secular equilibrium with which surface components). 

Table 6.2-2. Summary of the SZ Sampled Parameters Specific to Radionuclide (RN) Sorption 
Radionuclide (RN) Partitioned 
Between Solution and 
Parent Rock 
(No colloid transport) 
Radionuclide Partitioning Parameters Between 
Colloids and Parent Rock 
Radionuclide 
Irreversibly Sorbed to 
Colloids 
Sorption Between 
Solution and Rock Surface 
Sorption 
Between 
Solution 
and colloids 
RN 
Volcanic 
Units 
Alluvium 
Volcanic 
Units 
Alluvium 
Volcanic 
Units 
Alluvium 
Am 
No 
No 
Yes 
KD_Am_VO 
Yes 
KD_Am_AL 
Yes 
KD_Am_Col 
Yes 
CORVO 
Yes 
CORAL 
Cs 
No 
No 
Yes 
KD_Cs_VO 
Yes 
KD_Cs_AL 
Yes 
KD_Cs_Col 
No 
No 
Np 
Yes 
KDNPVO 
Yes 
KDNPAL 
No 
No 
No 
No 
No 
Pa 
No 
No 
Yes 
KD_Am_VO 
Yes 
KD_Am_AL 
Yes 
KD_Am_Col 
No 
No 
Pu 
No 
No 
Yes 
KD_Pu_VO 
Yes 
KD_Pu_AL 
Yes 
KD_Pu_Col 
Yes 
CORVO 
Yes 
CORAL 
Ra 
Yes 
KDRAVO 
Yes 
KDRAAL 
No 
No 
No 
No 
No 
Sr 
Yes 
KDSRVO 
Yes 
KDSRAL 
No 
No 
No 
No 
No 
Th 
No 
No 
Yes 
KD_Am_VO 
Yes 
KD_Am_AL 
Yes 
KD_Am_Col 
No 
No 
U 
Yes 
KDUVO 
Yes 
KDUAL 
No 
No 
No 
No 
No 
6.2.31 Colloidal Transport in the SZ (2.2.08.10.0A) 
FEP Description: Radionuclides may be transported in groundwater in the SZ as 
colloidal species. Types of colloids include true colloids, pseudo 
colloids, and microbial colloids. 
Descriptor Phrases: Advection of colloids in the SZ; Diffusion of colloids in the SZ; 
Sorption of colloids in the SZ 
Screening Decision: Included 
Related FEPs: 2.1.09.21.0B, 2.2.07.15.0A, 2.2.08.03.0A, 2.2.08.07.0A, 
2.2.08.09.0A 
TSPA Disposition: 
The colloid-facilitated transport of radionuclides is explicitly included in the SZ Transport 
Abstraction Model and the SZ 1-D Transport Model (SZ Flow and Transport Model Abstraction, 
BSC 2003 [167651], Section 6.2). Colloids are subject to advection in the fractures of tuff units 
and are not assumed to diffuse into the rock matrix. Radionuclide transport in association with 
colloids is simulated to occur by two modes: 1) as reversibly sorbed onto colloids, and 2) as 
irreversibly attached to colloids (BSC 2003 [167651], Sections 6.5.2.11 and 6.5.2.12). 
Reversible sorption of radionuclides may occur onto any colloidal material present in the 

groundwater, and measurements of natural colloids in groundwater of the SZ include mineral and 
microbial colloids. Colloids with irreversibly attached radionuclides originate from the 
degradation of the glass waste form in the repository (Waste Form and In-drift 
Colloids-Associated Radionuclide Concentrations: Abstraction and Summary, BSC 2003 
[166845], Section 6.3.1). The parameters related to reversible sorption onto colloids are 
Kd_Am_Col, Kd_Pu_Col, Kd_Cs_Col, and Conc_Col. The parameters related to the retardation 
of colloids with irreversibly attached radionuclides are CORVO and CORAL (BSC 2003 
[167651], Table 6-2). 
6.2.32 Groundwater Discharge to Surface Within the Reference Biosphere (2.2.08.11.0A) 
FEP Description: Radionuclides transported in groundwater as solutes or solid 
materials (colloids) from the far field may discharge at specific 
entry points that are within the reference biosphere. Natural 
surface discharge points, including those resulting from water table 
or capillary rise, may be surface water bodies (rivers, lakes), 
springs, wetlands, holding ponds, or unsaturated soils. 
Descriptor Phrases: Radionuclide release to biosphere (surface discharge at receptor); 
Water table elevation 
Screening Decision: Included 
Related FEPs: 1.3.07.01.0A, 1.3.07.02.0A, 1.4.07.01.0A, 1.4.07.02.0A, 
2.3.11.04.0A 
TSPA Disposition: 
The groundwater system in the vicinity of the hypothetical communitys well system is modeled 
such that all the contaminants discharged at the 18-km boundary are intercepted by the 
communitys wells (SZ Flow and Transport Model Abstraction, BSC 2003 [167651], Section 
6.2). Direct discharge of groundwater to the surface via springs, unsaturated soils, etc. is 
bounded by the simplifying assumption of complete capture of the contaminant plume in the 
wells. 
Direct discharge points (including those resulting from water table rise to form surface water 
bodies (rivers, lakes), springs, wetlands, and holding ponds at the accessible environment) would 
first be withdrawn by a well supplying the hypothetical farming community (10 CFR 63.332 
[156605]). Thus, these potential entry points to the accessible environment are implicitly 
included through the representative volume extracted by the hypothetical community well. 
Documentation as to the effects of unsaturated soils and capillary wicking on releases to the 
accessible environment fall under the biosphere model domain and discussed in the biosphere 
FEP analysis report (Evaluation of Features, Events and Processes for the Biosphere Model, 
BSC 2003 [165843], Section 6.2.14). 

6.2.33 Microbial Activity in the SZ (2.2.09.01.0A) 
FEP Description: Microbial activity in the SZ may affect radionuclide mobility in 
rock and soil through colloidal processes, by influencing the 
availability of complexing agents, or by influencing groundwater 
chemistry. 
Descriptor Phrases: Microbial effects on sorption in the SZ 
Screening Decision: ExcludedLow consequence 
Related FEPs: 2.2.08.01.0A, 2.2.08.03.0A, 2.2.08.06.0A, 2.2.11.01.0A, 
2.2.10.04.0A, 2.2.10.08.0A, 2.2.10.13.0A 
Screening Argument: 
Microbial activity can potentially change groundwater pH and Eh, and introduce additional 
complexing agents, which could affect Kd distributions. Of interest is sorption behavior of a 
limited number of elements, particularly U and Np, which are affected by variations in water 
chemistry. Microbial activity is more favorable in unsaturated conditions, where pores are less 
than 100% liquid saturated thus favoring vapor exchange and microbial growth resulting in the 
UZ including this FEP (Features, Events, and Processes in UZ Flow and Transport BSC 2003 
[164873], Section 6.1.36). However in the SZ evidence of microbial activity is lacking, which is 
supported by geochemical analysis of groundwater samples taken from SZ wells within the 
Yucca Mountain vicinity (DTN: GS931100121347.007 [149611] and DTN: 
GS010308312322.003 [154734]). Results from the above analysis found little to no organic 
carbon in these waters. Organic carbon is a bi-product of microbial activity. It is logically 
concluded, because there is little organic carbon found in SZ waters, there is insignificant 
microbial activity in the SZ regime. 
Additionally, geochemical analysis indicates current SZ groundwater along the SZ transport path 
is paleoclimate recharge water (Geochemical and Isotopic Constraints on Groundwater Flow 
Directions and Magnitudes, Mixing, and Recharge at Yucca Mountain, BSC 2003 [167211], 
Section 7.1.2), reflective of cooler climatic conditions and cooler recharge waters (BSC 2003 
[167211], Section 6.3). Paleoclimate recharge waters have higher carbon contents (which are 
components of inorganic complexing agents) and higher concentrations of dissolved CO2 gas. 
Higher CO2 gas concentrations contribute to higher oxidation states (Eh potential) and lower pH 
in resident waters, resulting in solutions that are more aggressive, participate in more dissolution 
and precipitation along the transport path, and contribute to more surface complexing sorption 
sites and the production of inorganic complexing agents. Two end member groundwater 
compositions that could exist within the SZ, reflective of the large variability in paleoclimate 
recharge waters, were used in deriving the Kd distributions (water from wells UE-25p#1 and J-
13, Site-Scale Saturated Zone Transport, BSC 2003 [167208], Attachment I). The resulting 
distributions used to represent the uncertainty in Kd and colloid parameter values, inclusive of U 
and Pu, are based on conditions in the natural system dominated by the more aggressive nature 

of paleoclimate recharge waters and overshadow any effects naturally occurring microbial 
activity would have on SZ water chemistry. 
Furthermore, radionuclide bearing colloidal formation, transport, and complexation are 
dominated by natural inorganic ligands and inorganic constituents generated by the degradation 
of emplaced waste forms and not those produced by SZ microbes (SZ Flow and Transport Model 
Abstraction, BSC 2003 [167651], Section 6.5.2.11 and 6.5.2.12). In conclusion, including the 
effects of microbial activity will not affect water chemistry used to derive Kd distribution and the 
presence of radionuclide bearing colloids. This FEP is excluded based on low consequence 
because it will not significantly change radiological exposures to the RMEI or radionuclide 
releases to the accessible environment. 
6.2.34 Thermal Convection Cell Develops in SZ (2.2.10.02.0A) 
FEP Description: Thermal effects due to waste emplacement result in convective 
flow in the saturated zone beneath the repository. 
Descriptor Phrases: Thermally-driven flow (convection) in the SZ 
Screening Decision: ExcludedLow consequence 
Related FEPs: 2.2.10.04.0B, 1.2.06.00.0A 
Screening Argument: 
A numerical model of the mountain scale effects of thermal loading on the host rock due to 
waste emplacement is evaluated in Mountain-Scale Coupled Processes (TH/THC/THM) (BSC 
2003 [166498], Section 6.5). The numerical model encompasses a domain extending from the 
ground surface to the water table. The model assessed changes in thermal, chemical and 
hydrologic properties as a result of heat induced stresses on the host rock. Model results indicate 
that the host rock temperatures reach a high of about 103C at approximately 1,000 years after 
waste emplacement (BSC 2003 [166498], Section 6.5.10). These elevated host rock 
temperatures produce a heat wave, originating at the repository and propagating outwards. At 
the water table, temperatures peak around 2,000 years and, depending on location within the 
repository footprint, locally vary between at 32 to 34C (BSC 2003 [166498], Section 6.3.1 and 
Figures 6.3.1-6, 6.3.1-7). These elevated temperatures are, at most, only 0 to 4C above ambient 
water table temperatures beneath the repository. Temperatures decrease to within 1 to 2C of 
ambient levels at about 5,000 years after waste emplacement. Relative to the scale of the SZ 
flow domain, this small increase in water table temperatures is local and small relative to the 
large variability in water table temperatures along the SZ flow and transport path, which ranges 
between 30 to 34C (Fridrich et al. 1994 [100575], Figure 8). Furthermore, there are locations 
along the SZ transport path where ambient temperatures increase with depth, with some 
temperatures as high as 40 to 45C (measured in well UE-25-p#1; Site-Scale Saturated Zone 
Flow Model, BSC 2003 [166262], Table 28). It is logically concluded that the increase in water 
table temperatures due to waste emplacement is a small perturbation in the SZ flow system given 
the large variability in groundwater temperatures along the SZ flow path. The resulting 

temperature perturbation will not create a thermally induced convection cell that will alter SZ 
flow paths. 
Thermal effects will have more of an impact on flow in the near field. In Features, Events, and 
Processes in UZ Flow and Transport (BSC 2003 [164873], Section 6.8.9), it is concluded that 
thermal effects due to waste emplacement will have an insignificant impact on flow in the UZ 
(FEP 2.2.10.01.0A Repository-induced thermal effects on flow in the UZ). In the UZ it is the 
potential of large-scale convection cells, driven by the vaporization and condensation cycle at the 
mountain scale that could potentially dominate UZ flow paths. It is logically concluded that if 
thermal effects on flow are excluded in the near field, then by deduction, they will have less of 
an impact in the far field. In conclusion, waste emplacement will not produce SZ thermal 
convection cells that will affect SZ flow paths; this FEP is excluded based on low consequence 
because it will not significantly change radiological exposures to the RMEI or radionuclide 
releases to the accessible environment. 
6.2.35 Natural Geothermal Effects on Flow in the SZ (2.2.10.03.0A) 
FEP Description: The existing geothermal gradient, and spatial or temporal 
variability in that gradient, may affect groundwater flow in the 
unsaturated and saturated zones. 
Descriptor Phrases Natural geothermal effects on flow in the SZ 
Screening Decision: Included 
Related FEPs: 1.2.06.00.0A, 2.2.10.02.0A, 2.2.10.04.0A, 2.2.10.08.0A, 
2.2.10.13.0A, 2.2.11.01.0A 
TSPA Disposition: 
Natural geothermal effects, as they influence fluid properties, are implicitly included in the SZ 
site-scale flow model. Groundwater flow is simulated in the Site-Scale Saturated Zone Flow 
Model (BSC 2003 [166262]), detailed disposition in Section 6.2) using a conservation of fluid-
rock energy equation in the numerical code FEHM V 2.20 (STN: 10086-2.20-00, LANL 2003 
[161725]). The fluid-rock energy equation is, in part, a function of permeability, density, 
viscosity, and temperature (BSC 2003 [166262], Section 6.5.3.7). For temperatures that range 
between 20oC to 100oC, the density of water changes by only a few percent. In contrast, the 
variation in water viscosity changes by a factor of 3.3 over the same temperature range. 
Consequently, natural geothermal effects on groundwater flow are more effectively captured by 
spatially varying viscosity rather than density. The Site-Scale Saturated Zone Flow Model (BSC 
2003 [166262], Section 6.5.3.7) assigns a specified temperature to each node, which varies with 
depth and is based on variable temperature measurements reported in Sass et al. (1988 [100644]). 
Permeability and viscosity are also assigned to each node. Temperatures are used to calculate 
nodal viscosities. Using the spatially varying viscosity, a fluid property, allows the calibration of 
hydraulic conductivity, a lumped fluid/rock property parameter. Estimated hydraulic 
conductivity at each node is calibrated to hydraulic head measurements, while nodal viscosities 

and temperatures remain fixed (BSC 2003 [166262], Section 6.5.3.7). Hydraulic heads are, in 
part, manifestations of multiple processes within the system, including geothermal effects. By 
calibrating hydraulic conductivity to hydraulic heads and keeping spatially varying temperature 
and viscosity fixed, geothermal effects on flow are implicitly captured. 
Additionally, Bechtel SAIC Company (BSC) performed a set of heat transport and flow 
simulations using measured temperature values in the SZ (BSC 2003 [166262], Section 7.4). 
The results of the coupled thermal modeling provide a general independent validation of the SZ 
site-scale flow model and validate the implicit modeling of geothermal effects in SZ flow. 
6.2.36 Thermo-Mechanical Stresses Alter Characteristics of Fractures Near Repository 
(2.2.10.04.0A) 
FEP Description: Heat from the waste causes thermal expansion of the surrounding 
rock, generating changes in the stress field that may change the 
fracture properties (both hydrologic and mechanical) of fractures in 
the rock. Cooling following the peak thermal period will also 
change the stress field, further affecting fracture properties near 
the repository. 
Descriptor Phrases: Thermal-mechanical effects (fractures in the UZ); 
Thermal-mechanical effects (fractures in the SZ); 
Thermal-mechanical effects (stress change) 
Screening Decision: ExcludedLow consequence 
Related FEPs: 2.2.10.13.0A, 2.2.11.01.0A, 2.2.10.08.0A, 2.2.10.04.0B, 
2.2.10.03.0A, 2.2.09.01.0A, 2.2.08.07.0A, 2.2.08.01.0A, 
2.2.07.14.0A, 2.2.06.02.0B, 1.2.02.01.0A, 
Screening Argument: 
The effects of thermal loading due to waste emplacement on fractures within the vicinity of the 
repository drifts are evaluated in Mountain-Scale Coupled Processes (TH/THC/THM) (BSC 
2003 [166498], Section 6.5). The numerical model encompasses a domain extending from the 
ground surface to the water table. Changes in hydrologic properties as a result of heat-induced 
stresses on the fractures and the host rock are assessed. Results indicate the highest thermally 
induced stresses are in the horizontal direction and occur at approximately 100 years (BSC 2003 
[166498], Section 6.5.11). Thermally induced stresses on fractures are compressive in nature 
below the repository and a combination of compressive and tensile in nature above the repository 
(BSC 2003 [166498], Sections 6.5.10 and 6.5.11). Compressive stresses transition to tensile 
stresses at approximately 180 m above the repository. The transition is due to a redistribution of 
horizontal stresses as the heat induced stress pulse encounters the unconfined and much cooler 
surface. Changes from compressive to tensile stresses are not seen below the repository. 

Vertical and sub-vertical fractures are affected most by these compressive stresses, with many 
fractures closing to their residual fracture aperture widths. Horizontal fracture apertures are least 
affected by thermally induced mechanical stresses; under compression stresses they tend to 
slightly open up. Thermally induced mechanical stresses primarily affect vertical fractures 
residing between 150 m above and 70 m below the repository and approximately 100 m lateral to 
the repository plane. Model results indicate it is the vertically aligned fracture that undergoes a 
significant reduction in permeability in response to compressive stresses from thermal loading 
(BSC 2003 [166498], Section 6.5.12). Horizontal fracture permeabilities located between 140 m 
above and 50 m below the repository are affected by thermal-mechanical stresses, but to a 
significantly lesser extent (BSC 2003 [166498], Figures 6.5.12-1, 6.5.12-2, 6.5.12-3). There are 
little to no changes in the permeabilities of both vertical and horizontal fractures located 
approximately 150 m below the repository. However, if a compression pulse were to affect SZ 
fractures at the water table, it would most likely affect vertical to sub-vertical fractures since it is 
the vertical to sub-vertical fractures that are most sensitive to compression stresses. Below the 
repository SZ flow primarily takes place in the fractures of the volcanic units. Therefore a 
reduction in permeability of vertical to sub-vertical fractures will promote flow in the less 
permeable rock and thus increase groundwater travel times. 
At 10,000 years, when the repository is well into a cooling phase, thermal-mechanical stresses do 
not impart significant on changes vertical fracture permeabilities beyond 50 m below the 
repository (BSC 2003 [166498], Figure 6.5.12-2). Because the top of the SZ is approximately 
335 m below the repository (DTN: GS000808312312.007 [155270], Table S00397 001; Total 
System Performance Assessment for the Site Recommendation, CRWMS M&O 2000 [153246], 
Figure 3.2-10), it is inferred that the effects of the thermally induced changes in the mechanical 
and hydrologic properties of SZ fractures will be insignificant during the cooling phase of the 
thermally induced stress pulse. 
In the analysis report Features, Events, and Processes in UZ Flow and Transport (BSC 2003 
[164873], Section 6.8.12), it is concluded that thermally induced stresses would have no effect 
on rock properties above and below the repository, including fracture properties. Specifically, 
thermally induced stresses would have no global effect on UZ fracture permeabilities below the 
repository or at most, would cause a reduction in permeability. Consequently, this FEP was 
excluded in the UZ based on low consequence. Since thermo-mechanical stresses are excluded 
in the near field, by deduction, the thermo-mechanical stress pulse will have less of an impact 
further out in the region of the SZ. 
To summarize, thermal-mechanical stresses cause little to no changes in horizontal hydrologic 
and mechanical properties in fractures located 50 m or more below the repository. Changes in 
vertical fracture properties are affected by thermal loading but are minimal at elevations 70 m 
below the repository. Because the top of the SZ is approximately 335 m below the repository, it 
is inferred that the effects of the thermal-mechanical induced stress changes will have little to no 
affect on SZ fractures. In conclusion, thermo-mechanical stresses imposed on fractures within 
the vicinity of the repository have little to no effect on SZ fractures properties. Thermo-
mechanical stresses on fractures in the SZ are excluded based on low consequence because they 
will not significantly change radiological exposures to the RMEI or radionuclide releases to the 
accessible environment. 

6.2.37 Thermo-Mechanical Stresses Alter Characteristics of Faults Near Repository 
(2.2.10.04.0B) 
FEP Description: Heat from the waste causes thermal expansion of the surrounding 
rock, generating changes in the stress field that may change the 
fault properties (both hydrologic and mechanical) in and along 
faults. Cooling following the peak thermal period will also change 
the stress field, further affecting fault properties near 
the repository. 
Descriptor Phrases: Thermal-mechanical effects (faults in the UZ); 
Thermal-mechanical effects (faults in the SZ); 
Thermal-mechanical effects (stress change) 
Screening Decision: ExcludedLow consequence 
Related FEPs 2.2.10.02.0A, 2.2.10.04.0A, 2.2.10.05.0A, 2.2.10.13.0A 
Screening Argument: 
For purposes of assessing the thermo-mechanical stresses on SZ faults due to waste 
emplacement, SZ faults can be considered as large fractures. Therefore, it is appropriate to 
review the impacts of thermal-mechanical stresses on fractures in order to understand similar 
stress effects on faults. The effects of thermal-mechanical loading due to waste emplacement on 
fractures within the vicinity of the repository drifts are evaluated in Mountain-Scale Coupled 
Processes (TH/THC/THM) (BSC 2003 [166498], Section 6.5). Results indicate the highest 
thermally induced stresses occur at approximately 100 years within the repository horizon, are 
horizontal in direction, and are compressive in nature below the repository (BSC 2003 [166498], 
Section 6.5.11). Moving away from the repository, stresses dampen. Above the repository 
thermally induced stresses are a combination of compressive and tensile in nature (BSC 2003 
[166498], Sections 6.5.10 and 6.5.11). Compressive stresses transition to tensile stresses at 
approximately 180 m above the repository. Changes from compressive to tensile stresses are not 
seen below the repository. Model results indicate thermal-mechanical stresses induced from 
waste emplacement do not significantly affect SZ vertical and sub-vertical and horizontal 
fracture hydrologic properties (FEP 2.2.10.04.0A Thermo-mechanical stresses alter 
characteristics of fractures near repository). 
Faults in the SZ are further from the heat source (the repository), larger than fractures, and 
extend deep into the SZ. A faults response to the same thermally induced stresses imposed on 
fractures will be mitigated due to their size and distance from the heat source. It is logically 
concluded, if thermally induced mechanical stresses will not affect fracture hydrologic properties 
in the SZ, then they will not affect fault properties within the SZ either. 

Furthermore, thermal effects on faults in the UZ due to waste emplacement are excluded due to 
low consequence (Features, Events, and Processes in UZ Flow and Transport, BSC 2003 
[164873], Section 6.8.11). Since thermo-mechanical stresses are excluded in the near field, by 
deduction, the thermo-mechanical stress pulse will have less of an impact further out in the 
region of the SZ and is also excluded. 
In summary, thermo-mechanical stresses due to waste emplacement imposed on faults located in 
the SZ are excluded due to low consequence because they will not significantly change 
radiological exposures to the RMEI or radionuclide releases to the accessible environment. 
6.2.38 Thermo-Mechanical Stresses Alter Characteristics of Rocks Above and Below the 
Repository (2.2.10.05.0A) 
FEP Description: Thermal-mechanical compression at the repository produces 
tension-fracturing in the PTn and other units above the repository. 
These fractures alter unsaturated zone flow between the surface 
and the repository. Extreme fracturing may propagate to the 
surface, affecting infiltration. Thermal fracturing in rocks below 
the repository affects flow and radionuclide transport to the 
saturated zone. 
Descriptor Phrases: Thermal-mechanical effects (rock properties in the UZ); 
Thermal-mechanical effects (rock properties in the SZ); 
Thermal-mechanical effects (stress change) 
Screening Decision: ExcludedLow consequence 
Related FEPs: 2.2.06.01.0A, 2.2.06.02.0A, 2.2.06.03.0A, 2.2.10.01.0B, 
2.2.10.04.0A, 2.2.10.04.0A, 2.2.10.04.0B, 
Screening Argument: 
A numerical model of the mountain scale effects of thermal loading on rock properties due to 
waste emplacement is evaluated in Mountain-Scale Coupled Processes (TH/THC/THM) (BSC 
2003 [166498], Section 6.5). The numerical model encompasses a domain extending from the 
ground surface to the water table. The model assessed changes in hydrologic properties as a 
result of heat-induced stresses on the host rock. Model results indicate that the largest thermally 
induced stresses are compressive in nature, are in the horizontal direction, and occur at the 
repository horizon at approximately 100 years after waste emplacement (BSC 2003 [166498], 
Section 6.5.11). The compression stress pulse loses strength as it moves outward from the 
repository. Since fractures have unconfined boundaries, a reduction in fracture apertures uses 
less work than a reduction of matrix porosity. Therefore it is fracture porosity (and attendant 
permeabilities) rather than matrix porosity, that is most affected by compressive stresses. Model 
results indicate vertically aligned fractures undergo a reduction in permeability in response to 
compressive stresses from thermal loading (BSC 2003 [166498], Section 6.5.12). Below the 
repository, compressive stresses primarily affect vertical to sub-vertical fractures and their 

permeabilities, in a region that extends approximately 100 m to 150 m directly below the 
repository (BSC 2003 [166498], Figure 6.5.12-3). At the water table thermal-mechanical 
stresses are not enough to produce a compression stress to significantly affect fracture 
permeability the SZ (see FEP 2.2.10.04.0AThermo-mechanical stresses alter characteristics of 
fractures near repository). Since fractures are more susceptible to thermally induced stresses 
and, at the water table, their hydrologic properties are not significantly affected by compressive 
stresses, then it is inferred neither will matrix hydrologic properties be affected by thermally 
induced stresses (see FEP 2.2.10.04.0AThermo-mechanical stresses alter characteristics of 
fractures near repository). 
Additionally, thermal-mechanical stresses affect the near field environment to a greater extent 
than the far-field region, the province of the SZ. Thermo-mechanical stresses on the UZ rock 
properties are excluded in the UZ (BSC 2003 [164873], Section 6.8.12). By deduction, thermo-
mechanical stresses will have less of an effect in the far-field and should be excluded as well. 
Thermal mechanical stresses in the units above the repository is a UZ issue and outside the 
province of the SZ. A screening decision with respect to thermal fracturing of these units is 
found in Features, Events, and Processes in UZ Flow and Transport (BSC 2003 [164873], 
Section 6.8.12). 
In summary, thermo-mechanical stresses on the SZ rock properties are excluded due to low 
consequence because they will not significantly change radiological exposures to the RMEI or 
radionuclide releases to the accessible environment. 
6.2.39 Thermo-Chemical Alteration in the SZ (Solubility, Speciation, Phase Changes, 
Precipitation/Dissolution) (2.2.10.08.0A) 
FEP Description: Thermal effects may affect radionuclide transport directly by 
causing changes in radionuclide speciation and solubility in the SZ, 
or, indirectly, by causing changes to host rock mineralogy that 
affect the flow path. Relevant processes include volume effects 
associated with silica phase changes, precipitation and dissolution 
of fracture filling minerals (including silica and calcite), and 
alteration of zeolites and other minerals to clays. 
Descriptor Phrases: Thermal-chemical effects (precipitation/dissolution in the SZ); 
Thermal-chemical effects (alteration in the SZ); Thermal-chemical 
effects (solubility limits in the SZ) 
Screening Decision: ExcludedLow consequence 
Related FEPs: 2.2.10.04.0A, 2.2.10.13.0A, 2.2.10.03.0A, 2.2.09.01.0A, 
2.2.08.09.0A, 2.2.08.07.0A, 2.2.08.01.0A, 2.2.07.14.0A, 
1.2.06.00.0A 

Screening Argument: 
Two primary components that affect mineral water interactions are CO2 concentrations and pH. 
Of the two components, CO2 concentrations are more sensitive to changes in temperature. Small 
changes in CO2 concentrations greatly affect pH variability. Therefore, it is possible that 
temperature variations along the SZ flow path can result in changes in SZ rock mineralogy. 
CO2 becomes less soluble at elevated temperatures. As temperatures increase CO2 exsolves out 
of solution causing pH to rise and calcite to precipitate in pores and fractures. Calcite 
precipitation in pores and along fractures can decrease permeability. As temperatures drop, CO2 
dissolution increases, potentially causing dissolution of calcite in pores and fractures. Calcite 
dissolution in fracture linings and within pore spaces can cause permeability to increase. 
Dissolution of CO2 bearing minerals can occur if they come into contact with low pH waters, 
thus increasing permeability and porosity. Therefore, a shift to lower pH bearing waters can 
cause calcite bearing minerals to dissolve, resulting in an increase in porosity and permeability. 
A numerical model of the mountain scale effects of thermal loading on the host rock due to 
waste emplacement is evaluated in Mountain-Scale Coupled Processes (TH/THC/THM) (BSC 
2003 [166498], Section 6.5). The model encompasses a domain extending from the ground 
surface to the water table and assesses changes in the water chemistry and mineralogy due to 
thermal loading at the repository. Model results indicate the host rock temperatures at the 
repository reach a high of about 103C at approximately 1,000 years after waste emplacement 
(BSC 2003 [166498], Section 6.5.10). A heat wave is produced, originating at the repository and 
propagating outwards. These elevated temperatures cause CO2 to exsolve out of solution above 
and below the repository. Just above the water table, within the repository footprint, 
temperatures peak around 2,000 years and locally vary between at 32 to 34C (BSC 2003 
[166498], Section 6.3.1 and Figures 6.3.1-6, 6.3.1-7). Variability in temperature can cause 
significant variability in CO2 concentrations and promote precipitation and/or dissolution of 
calcite in fractures and pore spaces. Modeling results indicate CO2 concentrations just above the 
water table do not vary significantly during the modeled time period (BSC 2003 [166498], 
Figures 6.4-12 and 6.4-16). Concurrently, no significant precipitation or dissolution of calcite 
bearing minerals in fracture fillings is seen (BSC 2003 [166498], Section 6.4.3.3.3 and Figure 
6.4-18). As such, it is logically concluded that if there is no measurable precipitation or 
dissolution of calcite in fracture fillings just above the water table due to thermal loading, there 
will be no measurable precipitation or dissolution of calcite along the SZ transport path due to 
thermal loading. 
Model results show pH concentrations above the water table vary between 8.14 and 8.45. 
Variations in pH just above the water table are not accompanied with noticeable precipitation or 
dissolution minerals such as calcite in fracture fillings (BSC 2003 [166498], Section 6.4.3.3.1, 
Figures 6.4-12 and 6.4-13; and Section 6.4.3.3.2, Figures 6.4-16 and 6.4-17). 
Temperatures at or above 50oC facilitate mineral-water reactions, causing vitric and silica 
bearing minerals to degrade to zeolites and other secondary minerals (which include clays). 
Zeolites tend to have the highest porosity and sorption capacity of all the secondary minerals. 
These types of mineral alterations can change sorption capacity, porosity and permeability in the 

SZ. Since temperatures at the water table stay within the low 30oC range, it is logically 
concluded there will be no alteration of silicic bearing minerals in the SZ. This is corroborated 
with modeling results reported in BSC 2003 ([166498]); alteration of silicate bearing minerals 
decreases with distance from the repository. Minimal-to-no mineral alteration is seen just above 
the water table (BSC 2003 [166498], Section 6.4.3.3 and Figures 6.4-20 through 6.4-24). Any 
mineral alteration at the water table would be degradation of silicic and vitric minerals to zeolites 
and other clays, which have a high sorption capacity. However, no credit is being taken for 
sorption onto zeolites that reside along the SZ flow path (Site-Scale Saturated Zone Transport, 
BSC 2003 [167208], Table 6.4-1). Consequently, any possible alteration of zeolites in the SZ 
will not affect the SZ barrier capability. 
The SZ Flow and Transport Model Abstraction (BSC 2003 [167651]) does not implement a 
solubility limit for each transported radionuclide. The radionuclide concentration that is 
introduced into SZ from the UZ is unconstrained. Furthermore, radionuclides introduced in the 
UZ from the Engineered Barrier System (EBS) are also unconstrained; that is, the solubility is 
not reduced as radionuclides go from the higher temperature repository conditions to the UZ. 
Therefore, thermo-chemical alteration on radionuclide solubility will have no effect on 
radionuclide transport in the SZ. 
In the analysis report Features, Events, and Processes in UZ Flow and Transport (BSC 2003 
[164873], Section 6.8.14), thermal chemical effects on dissolution and precipitation in the Calico 
Hills units are evaluated. That analysis indicates that thermo-chemical effects are limited to the 
near field environment, are of short duration, and will not have a significant effect on UZ 
contaminant transport or the release to the accessible environment. Since thermo-chemical 
stresses are excluded in the near field, by deduction, the thermo-chemical alteration will have 
less of an impact further out in the region of the SZ and are also excluded. All of the above 
reasons support excluding this FEP due to low consequence because it will not significantly 
change radiological exposures to the RMEI or radionuclide releases to the accessible 
environment. 
6.2.40 Repository-Induced Thermal Effects on Flow in the SZ (2.2.10.13.0A) 
FEP Description: Thermal effects in the geosphere could affect the long-term 
performance of the disposal system, including effects on 
groundwater flow (e.g., density-driven flow), mechanical 
properties, and chemical effects in the SZ. 
Descriptor Phrases: Thermal effects on flow in the SZ; Time-dependent THC 
characteristics in the SZ (temperature, pH, density) 
Screening Decision: ExcludedLow consequence 
Related FEPs: 2.2.11.01.0A, 2.2.10.08.0A, 2.2.10.04.0A, 2.2.10.04.0B, 
2.2.10.03.0A, 2.2.09.01.0A, 2.2.07.14.0A 

Screening Argument: 
Numerical modeling of the mountain scale effects of thermal loading on the host rock due to 
waste emplacement is evaluated in Mountain-Scale Coupled Processes (TH/THC/THM) (BSC 
2003 [166498], Section 6.5). Model results indicate that the host rock temperatures at the 
repository will reach a high of about 103C at approximately 1,000 years after waste 
emplacement (BSC 2003 [166498], Section 6.5.10). These elevated temperatures produce a heat 
wave that originates at the repository and propagates outwards. Just above the water table 
temperatures peak around 2,000 years and, depending on location within the repository footprint, 
locally vary between at 32 to 34C (BSC 2003 [166498], Section 6.3.1 and Figures 6.3.1-6, 
6.3.1-7). These elevated temperatures are, at most, only 0 to 4C above ambient water table 
temperatures beneath the repository. The model indicates that elevated temperatures decrease to 
within 1 to 2C of ambient levels at approximately 5,000 years after waste emplacement. 
Ambient SZ water temperatures at the water table along the transport path range between 30 and 
34C (Fridrich et al. 1994 [100575], Figure 8). Relative to the scale of the SZ flow domain, this 
increase in water table temperatures is local and small relative to the large variability in water 
table temperatures along the SZ flow and transport path. Furthermore, SZ ambient temperatures 
increase with depth along the transport path, with some temperatures as high as 40 to 45C in 
units where transport takes place (measured in well UE-25p#1 Site-Scale Saturated Zone Flow 
Model, BSC 2003 [166262], Table 28), and as temperatures increase, there is a potential for CO2 
to exsolve out of solution causing pH to rise and calcite to precipitate in pores and fractures. 
Calcite precipitation in pores and along fractures can decrease permeability. Just above the 
water table, variations in both pH (ranging between 8.14 to 8.45) and CO2 concentrations are not 
accompanied with noticeable precipitation or dissolution minerals such as calcite in fracture 
fillings (BSC 2003 [166498], Sections 6.4.3.3.1, 6.4.3.3.2, 6.4.3.3.2 and Figures 6.4-12, 6.4-13, 
6.4-16, 6.4-17, and 6.4-18). It is logically concluded that if a thermal pulse emanating from the 
repository does not significantly increase pH and CO2 concentrations at the water table, then 
there will not be a significant increase of these two components in the SZ flow domain farther 
away from the heat source. 
Temperature dependent sorption is not modeled in the SZ. Sorption is a temperature dependent 
process and increases as temperature increases. An increase in groundwater temperatures would 
increase the sorption capacity of the transported radionuclides, thus retarding transport to the 
accessible environment. Since modeled radionuclide partitioning coefficients in the SZ are 
based on ambient SZ temperatures, an increase in sorption capacity due to an increase in SZ 
water temperatures would not have an adverse effect on performance. 
Elevated temperatures of radionuclide bearing waters would be less dense than ambient waters. 
Density and temperatures gradients would promote lateral dispersion along the transport path. 
Lateral dispersion would reduce concentrations and thus reduce exposure to the RMEI. 
Therefore, temperature-induced density effects would not have an adverse effect on 
performance. 
All of the above support the conclusion that repository-induced thermal effects on flow in the SZ 
can be excluded due to low consequence because they will not significantly change radiological 
exposures to the RMEI or radionuclide releases to the accessible environment. 

6.2.41 Gas Effects in the SZ (2.2.11.01.0A) 
FEP Description: Pressure variations due to gas generation may affect flow patterns 
and contaminant transport in the SZ. Degassing could affect flow 
and transport of gaseous contaminants. Potential gas sources 
include degradation of repository components and naturally 
occurring gases from clathrates, microbial degradation of organic 
material, or deep gases in general. 
Descriptor Phrases: Gas pressure effects on flow in the SZ; Naturally occurring gases 
in the SZ 
Screening Decision: ExcludedLow consequence 
Related FEPs: 2.2.10.04.0A, 2.2.10.13.0A, 2.2.10.03.0A, 2.2.09.01.0A, 
2.2.07.14.0A 
Screening Argument: 
The effects of gas pressurization are excluded on several bases. There is no evidence of 
large-scale gas buildup in, or flow of gas through, the SZ. Additionally, no significant volumes 
of oil or gas have been found in the Yucca Mountain vicinity, and proven source rocks in the 
region are lacking (French 2000 [107425], p. 5). While the geologic elements required for a 
petroleum system are present in the Yucca Mountain region, stratigraphic seals (important in a 
viable hydrocarbon producing region) are not well developed in the Yucca Mountain area, 
causing the hydrocarbon potential to be classified as low (French 2000 [107425], p. 39). 
In the unlikely event that gas-generating processes occur in the sedimentary rocks below the 
tuffs, the influence on the flow and transport pathways would tend to be highly localized. Given 
the coarse grid used in the flow model and the uncertainty in the flow and transport pathways 
incorporated in the model, undetected localized processes or features that divert flow would 
either be too small in scale to impact the simulations or would be accounted for in the 
heterogeneity and parameter uncertainties in the Saturated Zone Flow and Transport (SZFT) 
model. As a result, it would not have a significant effect on the effective model parameter values 
and therefore would not affect radionuclide release to the accessible environment. 
The presence of clathrates and microbial degradation of organic components are two potential 
sources of gas that may affect flow and transport in the SZ. Clathrates, methane gas molecules 
bound in a cage-like structure made up of water molecules, form under high pressures and low 
temperatures. Clathrates are found in polar and deep oceanic regions (Henriet and Mienert, 1998 
[166162], pp. 9-11). Exploratory drilling has the potential to penetrate clathrates fields, which 
could release a large volume of gas in the SZ, in turn affecting SZ flow patterns. Clathrates are 
not a potential hydrocarbon source in the Yucca Mountain vicinity since low-temperature, high-
pressure conditions do not exist in the region, which are requisite conditions for clathrate 
formation. 

Microbial degradation of organic components is not considered a potential gas source in the SZ. 
Analysis of groundwater samples taken from SZ wells within the Yucca Mountain vicinity have 
found little to no organic carbon (DTN: GS931100121347.007 [149611] and DTN: 
GS010308312322.003 [154734]). Organic carbon is a bi-product of microbial activity. It is 
logically concluded, because there is little organic carbon found in SZ waters, there is 
insignificant microbial activity in the SZ producing CO2 gas that would affect SZ flow and 
transport. 
Since the repository is situated in the UZ approximately 335 m above the water table (DTN: 
GS000808312312.007 [155270], Table S00397 001; Total System Performance Assessment for 
the Site Recommendation, CRWMS M&O 2000 [153246], Figure 3.2-10), degradation of 
repository components that would potentially produce gas will not affect flow and transport in 
the SZ. A screening decision related to gas production from repository components as it affects 
UZ flow and transport is found in Features, Events, and Processes in UZ Flow and Transport 
(BSC 2003 [164873], Section 6.6.2). 
In summary, the potential effects of naturally occurring gases in the geosphere can be excluded 
from the SZFT model based on low consequence because they will not significantly change 
radiological exposures to the RMEI or radionuclide releases to the accessible environment. 
6.2.42 Undetected Features in the SZ (2.2.12.00.0B) 
FEP Description: This FEP is related to undetected features in the SZ portion of the 
geosphere than can affect long-term performance of the disposal 
system. Undetected but important features may be present, and 
may have significant impacts. These features include unknown 
active fracture zones, inhomogeneities, faults and features 
connecting different zones of rock, and different geometries for 
fracture zones. 
Descriptor Phrases: Undetected features (flow and pathways in the SZ); Undetected 
features (fractures in the SZ); Undetected features (faults in the SZ) 
Screening Decision: Included 
Related FEPs 2.2.07.14.0A, 2.2.07.13.0A, 2.2.07.12.0A, 2.2.03.01.0A, 
1.2.02.02.0A, 1.2.02.01.0A 
TSPA Disposition: 
Undetected features in the SZ, such as fracture zones, inhomogeneities, faults, gravel lenses and 
channels in the alluvium, and their potential impacts on groundwater flow are implicitly 
incorporated in the SZ Transport Abstraction Model and the SZ 1-D Transport Model through 
parameter distributions (SZ Flow and Transport Model Abstraction, BSC 2003 [167651], Section 
6.2); both models are described in BSC 2003 ([167651], Section 6.3). The generation of 

multiple flow and transport realizations, using stochastically sampled key parameters as input, 
significantly varies flow and transport pathways in the SZ. The key parameters that implicitly 
model undetected features (BSC 2003 [167651], Section 6.2) are (1) groundwater specific 
discharge (GWSPD), (2) horizontal anisotropy in the volcanic units (HAVO), (3) flowing 
interval spacing in the volcanic units (FISVO) and (4) sorption coefficients (Kdij) for 9 
radionuclides modeled in both the alluvium and volcanic units (parameters are described in BSC 
2003 ([167651], Sections 6.5.2.1, 6.5.2.10, 6.5.2.4, 6.5.2.8 and Table 6-8). A more detailed 
description of the manner in which undetected features are implicitly captured through the use of 
lumped parameters is provided in the Supplemental Discussion for this FEP in this SZ FEP 
report. 
Supplemental Discussion: 
Modeling of natural processes is, in many instances, based on using lumped parameters. 
Lumped parameters are parameters that are based on empirical observations (i.e., not all 
processes or first order physics are explicitly understood or known). Hydraulic conductivity, 
permeability, and transmissivity are examples of lumped parameters. In matching hydraulic 
heads (a response to the system) with variable lumped parameters such as permeability, 
anisotropy ratios, and dispersivity (to name a few), one implicitly incorporates undetected 
features into the model. 
Groundwater specific discharge (GWSPD) in the SZ may be enhanced due to the presence of 
undetected features. In the alluvium features could be undetected gravel lenses and channels, 
and in the volcanics these could be undetected faults and fractures or fracture clusters. 
Uncertainty in groundwater specific discharge in the SZ is based on data gathered from single- 
and multi-well hydrologic testing in the volcanic units near Yucca Mountain and field testing in 
the alluvium at the alluvial tracer complex (ATC). In the TSPA, the GWSPD parameter is a 
multiplication factor applied to all SZ permeability values and specified boundary fluxes (BSC 
2003 [167651], Section 6.5.2.1) to effectively scale the simulated specific discharge and 
implicitly model the effects undetected features may have on groundwater specific discharge. 
Additional parameters that model undetected SZ features are flowing interval porosity in the 
volcanic units (FPVO, longitudinal dispersivity (LDISP) incorporated in both the volcanic units 
and the alluvium, effective porosity in the alluvium units 7 and 19 (NV7 and NV19), alluvium 
bulk density (bulk density), and sorption coefficients (Kd) for 9 radionuclides modeled in both 
the alluvium and volcanic units. Additionally, in the SZ Transport Abstraction Model (BSC 
2003 [167651], Section 6.5.2.2), undetected features are accounted for through the probabilistic 
boundaries of the alluvium uncertainty zone. The western and northern boundaries of the 
alluvial uncertainty zone are defined with the sampled parameters FPLAW and FPLAN. The 
above parameters that implicitly model undetected features are described in BSC 2003 [167651], 
Sections 6.5.2.1, 6.5.2.2, 6.5.2.10, 6.5.2.4, 6.5.2.5, 6.5.2.7, 6.5.2.3, 6.5.2.8, respectively. 
6.2.43 Groundwater Discharge to Surface Outside the Reference Biosphere (2.3.11.04.0A) 
FEP Description: Radionuclides transported in groundwater as solutes or solid 
materials (colloids) from the far field may discharge at specific 

entry points that are outside the reference biosphere. Natural 
surface discharge points, including those resulting from water table 
or capillary rise, may be surface water bodies (rivers, lakes), 
springs, wetlands, holding ponds, or unsaturated soils. 
Descriptor Phrases: Radionuclide release to biosphere (surface discharge away from 
receptor) 
Screening Decision: Excludedby regulation 
Related FEPs: 2.2.08.011.0A, 1.4.07.02.0A, 1.4.07.01.0A 
Screening Argument: 
Groundwater discharge to the surface outside the reference biosphere is excluded on a regulatory 
basis defined in 10 CFR 63 [156605] as follows. The reference biosphere is defined in Section 
63.2 as: 
The environment inhabited by the reasonably maximally exposed individual 
(RMEI). 
Section 63.312(a) specifies the location where the RMEI will reside as: 
The reasonably maximally exposed individual is a hypothetical person who 
meets the following criteria: 
Lives in the accessible environment above the highest concentration of 
radionuclides in the plume of contamination. 
It is only the highest dose that is calculated in the performance assessment. And by definition, 
the reference biosphere, where groundwater is withdrawn to calculate the dose to the RMEI, is 
located within the accessible environment and is above the highest radionuclide concentration of 
the contaminated plume. Groundwater discharge outside the reference biosphere, which by 
definition would have a lower radionuclide concentration than that withdrawn from the reference 
biosphere, is excluded by regulation. 
6.2.44 Radioactive Decay and Ingrowth (3.1.01.01.0A) 
FEP Description: Radioactivity is the spontaneous disintegration of an unstable 
atomic nucleus that results in the emission of subatomic particles. 
Radioactive isotopes are known as radionuclides. Radioactive 
decay of the fuel in the repository changes the radionuclide content 
in the fuel with time and generates heat. Radionuclide quantities in 
the system at any time are the result of the radioactive decay and 
the growth of daughter products as a consequence of that decay 
(i.e., ingrowth). Over a 10,000-year performance period, these 

processes will produce daughter products that need to be 
considered in order to adequately evaluate the release and transport 
of radionuclides to the accessible environment. 
Descriptor Phrases: Radioactive decay and ingrowth (in the SZ) 
Screening Decision: Included 
Related FEPs: 3.2.07.01.0A, 2.2.08.07.0A, 2.2.08.01.0A 
TSPA Disposition: 
Radioactive decay during transport in the SZ is explicitly included in the convolution integral 
method used to couple the SZ Transport Abstraction Model with the TSPA model and in the SZ 
1-D Transport Model (SZ Flow and Transport Model Abstraction, BSC 2003 [167651], Section 
6.2; both models are described in BSC 2003 [167651], Section 6.3). Ingrowth is accounted for in 
two different ways in the TSPA models. First, the radionuclide mass entering the SZ at the water 
table is adjusted to account for the potential ingrowth of some radionuclide daughter products, 
resulting in a boosting of the initial inventory of some daughter products (BSC 2003 
([167651], Section 6.3.1). This approach is a conservative simplification that overestimates the 
mass of these daughter radionuclides being transported in the SZ. Second, a separate set of SZ 
transport simulations is run to calculate explicitly the decay and ingrowth for the four main 
radionuclide chains, using the SZ 1-D Transport Model (BSC 2003 [167651], Section 6.3.2 and 
6.5.1.2). These two ways of accounting for ingrowth in the SZ transport simulations differ from 
the approach used in the UZ transport simulations because of the differing numerical methods 
used. The convolution integral method, as implemented in the SZ Transport Abstraction model, 
is not able to explicitly calculate radioactive ingrowth and transport of daughter products. 
Consequently, the simplified approach of daughter product source boosting is used for some 
direct daughter products, and the SZ 1-D Transport Model is used for the longer decay chains. 
6.2.45 Isotopic Dilution (3.2.07.01.0A) 
FEP Description: Mixing or dilution of the radioactive species from the waste with 
species of the same element from other sources (i.e., stable and/or 
naturally occurring isotopes of the same element) could lead to a 
reduction of the radiological consequences. 
Descriptor Phrases: Radionuclide dilution (by naturally occurring isotopes) 
Screening Decision: ExcludedLow consequence 
Related FEPs: 2.2.08.03.0A, 2.2.08.06.0A, 2.2.08.07.0A, 2.2.08.01.0A, 
2.2.07.16.0A, 3.1.01.01.0A 

Screening Argument: 
Isotopic dilution in the SZ could occur if elements that are in the waste also occur naturally. 
Prime examples of naturally occurring isotopes in SZ groundwaters are those of strontium, (84S, 
86S 87S 88S), uranium (234U and 238U), and carbon (12C and 13C) (Geochemical and Isotopic 
Constraints on Groundwater Flow Directions and Magnitudes, Mixing, and Recharge at 
Yucca Mountain, Nevada, BSC 2003 [167211], Section 6.7.1.2). In the Saturated Zone Flow and 
Transport (SZFT) model the concentration of radionuclides released from the UZ to the SZ is not 
diluted due to the presence of naturally occurring isotopes such as those listed above. Isotopic 
dilution would dilute the concentration of radioactive contaminants in the groundwater 
withdrawn from wells in the hypothetical farming community, thus reducing radiological 
exposure to the RMEI. Therefore, isotopic dilution is excluded based on low consequence 
because it has no adverse effects on performance. 
6.2.46 Recycling of Accumulated Radionuclides from Soils to Groundwater (1.4.07.03.0A) 
FEP Description: Radionuclides that have accumulated in soils (e.g., from deposition 
of contaminated irrigation water) may leach out of the soil and be 
recycled back into the groundwater as a result of recharge (either 
from natural or agriculturally induced infiltration). The recycled 
radionuclides may lead to enhanced radionuclide exposure at the 
receptor. 
Descriptor Phrases: Radionuclide accumulation (soil); Radionuclide release to the 
biosphere (recycling) 
Screening Decision: Excludedby regulation 
Related FEPs: 1.4.07.01.0A, 1.4.07.02.0A, 2.3.02.02.0A, 2.3.11.03.0A, 
2.4.09.01.0B 
Screening Argument: 
Uptake of radionuclide bearing groundwater by agricultural wells, then recycling this water back 
to the groundwater due to leaching out of cultivated fields, is excluded on a regulatory basis 
(Economy 2004 [167914]). The rationale referenced in Economy 2004 [167914] is summarized 
below. 
It is stated in 10 CFR 63.312 (b) [156605] that the RMEI communitys well be located within the 
accessible environment above the highest radionuclide concentration of the contaminated plume. 
The plumes highest concentration is projected to arrive to the accessible environment along the 
primary groundwater flow direction at 18 km down gradient from the repository. In accordance 
with 10 CFR Part 63 Subpart 63.332 (3) [156605] the annual water demand of 3000 acre-feet 
will be used to determine the concentration of radionuclides extracted at this location. Per 
requirements stated in 10 CFR 63.312 (b) the RMEI partakes in the same diets and lifestyles 
representative of the people now residing in the farming community of Amargosa Valley. The 

farming community of Amargosa Valley is located approximately 12 km down gradient from the 
accessible environment. 
In 10 CFR 63.305 (b) the regulation specifically prohibits the projection of changes in society, 
the biosphere (other than climate), and increases or decreases in human knowledge or technology 
at the time of license application submittal. Per these requirements, the location of the RMEI 
community, the communitys everyday activities, and RMEIs water supply well be held 
constant through time and are consistent with current practices. Therefore, consistent with the 
points above, and to avoid unsupportable speculation regarding the future activities of the 
farming community, the following regulatory position is adopted with respect to the location of 
the RMEI community and the communitys well. 
The concentration of radionuclides in the contaminated plume is based on the RMEIs well 
withdrawing 3,000 acre-feet per year. The RMEI does not pump the entire 3000 acre-feet of 
ground water. The RMEIs well pumps only that amount of water necessary to supply drinking 
water for the RMEI, irrigate a small vegetable garden, and irrigate a small orchard or pasture. 
The RMEIs well is located at the accessible environment. Future cultivation, farming and 
irrigation sites undertaken by the RMEIs community are at the same location during the time of 
license application submittal. That is, all water use activities undertaken by the RMEIs farming 
community (which includes all agricultural uses) are located approximately 12 km down-
gradient from the farming communitys well. This presumes the well that withdraws the 
representative volume of groundwater to be used in determining the RMEI dose is not engaged 
in center-pivot irrigation. 
While the RMEI is a rural resident, it is not a subsistence farmer and does not have significant 
acreage under cultivation. The RMEIs well does not engage in center pivot agricultural 
irrigation. Because the model adopts the position that the RMEIs irrigation water is withdrawn 
from wells located at the 18-km accessible environment boundary, which is 12 km up-gradient 
from the cultivated fields located in Amargosa Valley, recycling of contaminated water will not 
occur and radionuclides will not accumulate in soils. In conclusion, recycling of radionuclides is 
excluded on the basis of inconsistency with the requirements of 10 CFR 63.305(b) and 63.312(b) 
(Economy 2004 [167914]). 

7. CONCLUSIONS 
7.1 SATURATED ZONE SCREENED FEPS 
The following 46 FEPs were evaluated with respect to SZ screening criteria given in Sections 
4.2.2 and 4.3. By default, a FEP will be included in the TSPA if it cannot be excluded based on 
the criteria. For included FEPs, the TSPA-LA Dispositions provided in Section 6.2 describe how 
each FEP is included in the TSPA-LA (i.e., through a parameter or TSPA model or sub-model). 
For excluded FEPs, the screening decision is based on the screening criteria (by regulation, low 
probability, low consequence) and the technical basis for exclusion is elaborated in the Screening 
Arguments provided in Section 6.2. Table 7.1-1 summarizes the screening arguments for 
excluded FEPs and the TSPA dispositions for included FEPs. 
This document may be affected by technical product input information that requires 
confirmation. Any changes to the document that may occur as a result of completing the 
confirmation activities will be reflected in subsequent revisions. The status of the technical 
product input information quality can be confirmed by review of the DIRS database. 
Table 7.1-1. Summary of SZ FEPs Screening 
Section 
Number 
LA FEP Number 
FEP Name 
Screening Decision 
6.2.1 
1.2.02.01.0A 
Fractures 
Included 
6.2.2 
1.2.02.02.0A 
Faults 
Included 
6.2.3 
1.2.04.02.0A 
Igneous activity changes rock properties 
Excluded 
Low Consequence 
6.2.4 
1.2.04.07.0B 
Ash redistribution in groundwater 
Excluded 
Low Consequence 
6.2.5 
1.2.06.00.0A 
Hydrothermal activity 
Excluded 
Low consequence 
6.2.6 
1.2.09.02.0A 
Large-scale dissolution 
Excluded 
Low Consequence 
6.2.7 
1.2.10.01.0A 
Hydrologic response to seismic activity 
Excluded 
Low Consequence 
6.2.8 
1.2.10.02.0A 
Hydrologic response to igneous activity 
Excluded 
Low Consequence 
6.2.9 
1.3.07.01.0A 
Water table decline 
Excluded 
Low Consequence 
6.2.10 
1.3.07.02.0A 
Water table rise affects SZ 
Included 
6.2.11 
1.4.07.01.0A 
Water management activities 
Included 
6.2.12 
1.4.07.02.0A 
Wells 
Included 
6.2.46 
1.4.07.03.0A 
Recycling of accumulated radionuclides 
from soils to groundwater 
Excluded 
By Regulation 

Table 7.1-1. Summary of SZ FEPs Screening (Continued) 
Section 
Number 
LA FEP Number 
FEP Name 
Screening Decision 
6.2.13 
2.1.09.21.0B 
Transport of particles larger than colloids in 
the SZ 
Excluded 
Low Consequence 
6.2.14 
2.2.03.01.0A 
Stratigraphy 
Included 
6.2.15 
2.2.03.02.0A 
Rock properties of host rock and other 
units 
Included 
6.2.16 
2.2.06.01.0A 
Seismic activity changes porosity and 
permeability of rock 
Excluded 
Low Consequence 
6.2.17 
2.2.06.02.0A 
Seismic activity changes porosity and 
permeability of faults 
Excluded 
Low Consequence 
6.2.18 
2.2.06.02.0B 
Seismic activity changes porosity and 
permeability of fractures 
Excluded 
Low Consequence 
6.2.19 
2.2.07.12.0A 
Saturated groundwater flow in the 
geosphere 
Included 
6.2.20 
2.2.07.13.0A 
Water-conducting features in the SZ 
Included 
6.2.21 
2.2.07.14.0A 
Chemically-induced density effects on 
groundwater flow 
Excluded 
Low Consequence 
6.2.22 
2.2.07.15.0A 
Advection and dispersion in the SZ 
Included 
6.2.23 
2.2.07.16.0A 
Dilution of radionuclides in groundwater 
Included 
6.2.24 
2.2.07.17.0A 
Diffusion in the SZ 
Included 
6.2.25 
2.2.08.01.0A 
Chemical characteristics of groundwater in 
the SZ 
Included 
6.2.26 
2.2.08.03.0A 
Geochemical interactions and evolution in 
the SZ 
Excluded 
Low Consequence 
6.2.27 
2.2.08.06.0A 
Complexation in the SZ 
Included 
6.2.28 
2.2.08.07.0A 
Radionuclide solubility limits in the SZ 
Excluded 
Low Consequence 
6.2.29 
2.2.08.08.0A 
Matrix diffusion in the SZ 
Included 
6.2.30 
2.2.08.09.0A 
Sorption in the SZ 
Included 
6.2.31 
2.2.08.10.0A 
Colloidal transport in the SZ 
Included 
6.2.32 
2.2.08.11.0A 
Groundwater discharge to surface within 
the reference biosphere 
Included 
6.2.33 
2.2.09.01.0A 
Microbial activity in the SZ 
Excluded 
Low Consequence 
6.2.34 
2.2.10.02.0A 
Thermal convection cell develops in SZ 
Excluded 
Low Consequence 
6.2.35 
2.2.10.03.0A 
Natural geothermal effects on flow in the SZ
Included 
6.2.36 
2.2.10.04.0A 
Thermo-mechanical stresses alter 
characteristics of fractures near repository 
Excluded 
Low Consequence 
6.2.37 
2.2.10.04.0B 
Thermo-mechanical stresses alter 
characteristics of faults near the repository 
Excluded 
Low Consequence 

6.2.38 
2.2.10.05.0A 
Thermo-mechanical stresses alter 
characteristics of rocks above and below 
the repository 
Excluded 
Low Consequence 
6.2.39 
2.2.10.08.0A 
Thermo-chemical alteration in the SZ 
(solubility, speciation, phase changes, 
precipitation/dissolution) 
Excluded 
Low Consequence 
6.2.40 
2.2.10.13.0A 
Repository-induced thermal effects on flow 
in the SZ 
Excluded 
Low Consequence 
6.2.41 
2.2.11.01.0A 
Gas effects in the SZ 
Excluded 
Low Consequence 
6.2.42 
2.2.12.00.0B 
Undetected features in the SZ 
Included 
6.2.43 
2.3.11.04.0A 
Groundwater discharge to surface outside 
the reference biosphere. 
Excluded 
By Regulation 
6.2.44 
3.1.01.01.0A 
Radioactive decay and ingrowth 
Included 
6.2.45 
3.2.07.01.0A 
Isotopic dilution 
Excluded 
Low Consequence 
The conclusions from this document (FEP screening decisions and supporting rationale) are 
considered technical product output with no assigned DTN. The SZ FEP screening decision, 
TSPA-LA disposition (for included FEPs), or screening argument (for excluded FEPs), will be 
incorporated in the Yucca Mountain TSPA-LA FEP database. This database will contain all 
Yucca Mountain FEPs considered for TSPA-LA with FEP Number, Name, Description, and 
relevant FEP AMRs where specific FEPs are screened. The FEP database will also contain 
Descriptor Phrases, Screening Decisions (Include or Exclude), Screening Arguments, and TSPA 
Dispositions quoted from this and all other FEP AMRs. Documentation of the FEP database will 
be given in an AP-3.11Q report. All FEP information, including the 46 SZ FEPs considered in 
this report, will be submitted to Technical Data Management System by the Yucca Mountain 
FEP database team as a final LA FEP DTN. These final data will be qualified as Technical 
Product Output from the AP-3.11Q report. The final FEP DTN will supersede all of the previous 
DTNs. It will then be citable by any downstream documents, such as the Safety Analysis Report 
(SAR) or AMR Revisions. 

8. INPUTS AND REFERENCES 
8.1 DOCUMENTS CITED 
100088 Szabo, B.J.; Kolesar, P.T.; Riggs, A.C.; Winograd, I.J.; and Ludwig, K.R. 1994. 
"Paleoclimatic Inferences from a 120,000-Yr Calcite Record of Water-Table 
Fluctuation in Browns Room of Devils Hole, Nevada." Quaternary Research, 41, 
(1), 59-69. [New York, New York: Academic Press]. TIC: 234642. 
100131 D'Agnese, F.A.; Faunt, C.C.; Turner, A.K.; and Hill, M.C. 1997. Hydrogeologic 
Evaluation and Numerical Simulation of the Death Valley Regional Ground-Water 
Flow System, Nevada and California. Water-Resources Investigations Report 96-
4300. Denver, Colorado: U.S. Geological Survey. ACC: MOL.19980306.0253. 
100148 Forester, R.M.; Bradbury, J.P.; Carter, C.; Elvidge, A.B.; Hemphill, M.L.; 
Lundstrom, S.C.; Mahan, S.A.; Marshall, B.D.; Neymark, L.A.; Paces, J.B.; Sharpe, 
S.E.; Whelan, J.F.; and Wigand, P.E. 1996. Synthesis of Quaternary Response of the 
Yucca Mountain Unsaturated and Saturated Zone Hydrology to Climate Change. 
Milestone 3GCA102M. Las Vegas, Nevada: U.S. Geological Survey. ACC: 
MOL.19970211.0026. 
100183 Sweetkind, D.S.; Barr, D.L.; Polacsek, D.K.; and Anna, L.O. 1997. Administrative 
Report: Integrated Fracture Data in Support of Process Models, Yucca Mountain, 
Nevada. Milestone SPG32M3. [Las Vegas, Nevada]: U.S. Geological Survey. 
ACC: MOL.19971017.0726. 
100353 CRWMS M&O 1998. Saturated Zone Flow and Transport Expert Elicitation 
Project. Deliverable SL5X4AM3. Las Vegas, Nevada: CRWMS M&O. ACC: 
MOL.19980825.0008. 
100447 Gauthier, J.H.; Wilson, M.L.; Borns, D.J.; and Arnold, B.W. 1996. "Impacts of 
Seismic Activity on Long-Term Repository Performance at Yucca Mountain." 
Proceedings of the Topical Meeting on Methods of Seismic Hazards Evaluation, 
Focus '95, September 18-20, 1995, Las Vegas, Nevada. Pages 159-168. La Grange 
Park, Illinois: American Nuclear Society. TIC: 232628. 
100569 Domenico, P.A. and Schwartz, F.W. 1990. Physical and Chemical Hydrogeology. 
New York, New York: John Wiley & Sons. TIC: 234782. 
100575 Fridrich, C.J.; Dudley, W.W., Jr.; and Stuckless, J.S. 1994. "Hydrogeologic Analysis 
of the Saturated-Zone Ground-Water System, Under Yucca Mountain, Nevada." 
Journal of Hydrology, 154, 133-168. Amsterdam, The Netherlands: Elsevier. TIC: 
224606. 

100644 Sass, J.H.; Lachenbruch, A.H.; Dudley, W.W., Jr.; Priest, S.S.; and Munroe, R.J. 
1988. Temperature, Thermal Conductivity, and Heat Flow Near Yucca Mountain, 
Nevada: Some Tectonic and Hydrologic Implications. Open-File Report 87-649. 
[Denver, Colorado]: U.S. Geological Survey. TIC: 203195. 
100783 Ogard, A.E. and Kerrisk, J.F. 1984. Groundwater Chemistry Along Flow Paths 
Between a Proposed Repository Site and the Accessible Environment. LA-10188-
MS. Los Alamos, New Mexico: Los Alamos National Laboratory. ACC: 
HQS.19880517.2031. 
100967 Carrigan, C.R.; King, G.C.P.; Barr, G.E.; and Bixler, N.E. 1991. "Potential for 
Water-Table Excursions Induced by Seismic Events at Yucca Mountain, Nevada." 
Geology, 19, (12), 1157-1160. Boulder, Colorado: Geological Society of America. 
TIC: 242407. 
101018 Skagius, K. and Wingefors, S. 1992. Application of Scenario Development Methods 
in Evaluation of the Koongarra Analogue. Volume 16 of Alligator Rivers Analogue 
Project. SKI TR 92:20-16. DOE/HMIP/RR/92/086. Manai, New South Wales, 
Australia: Australian Nuclear Science and Technology Organisation. TIC: 231268. 
101173 Freeze, R.A. and Cherry, J.A. 1979. Groundwater. Englewood Cliffs, New Jersey: 
Prentice-Hall. TIC: 217571. 
101234 Cranwell, R.M.; Guzowski, R.V.; Campbell, J.E.; and Ortiz, N.R. 1990. Risk 
Methodology for Geologic Disposal of Radioactive Waste, Scenario Selection 
Procedure. NUREG/CR-1667. Washington, D.C.: U.S. Nuclear Regulatory 
Commission. ACC: NNA.19900611.0073. 
101276 O'Brien, G.M. 1993. Earthquake-Induced Water-Level Fluctuations at Yucca 
Mountain, Nevada, June 1992. Open-File Report 93-73. Denver, Colorado: U.S. 
Geological Survey. ACC: NNA.19930326.0022. 
103023 Young, R.A. 1972. Water Supply for the Nuclear Rocket Development Station at the 
U.S. Atomic Energy Commission's Nevada Test Site. Water-Supply Paper 1938. 
Washington, D.C.: U.S. Geological Survey. ACC: NNA.19870519.0070. 
103200 Thordarson, W.; Rush, F.E.; Spengler, R.W.; and Waddell, S.J. 1984. Geohydrologic 
and Drill-Hole Data for Test Well USW H-3, Yucca Mountain, Nye County, Nevada. 
Open-File Report 84-149. Denver, Colorado: U.S. Geological Survey. ACC: 
NNA.19870406.0056. 
103282 Kersting, A.B.; Efurd, D.W.; Finnegan, D.L.; Rokop, D.J.; Smith, D.K.; and 
Thompson, J.L. 1999. "Migration of Plutonium in Ground Water at the Nevada Test 
Site." Nature, 397, ([6714]), 56-59. [London, England: Macmillan Journals]. TIC: 
243597. 

103283 La Camera, R.J.; Locke, G.L.; and Munson, R.H. 1999. Selected Ground-Water Data 
for Yucca Mountain Region, Southern Nevada and Eastern California, Through 
December 1997. Open-File Report 98-628. Carson City, Nevada: U.S. Geological 
Survey. ACC: MOL.19990921.0120. 
103731 CRWMS M&O 1998. Probabilistic Seismic Hazard Analyses for Fault 
Displacement and Vibratory Ground Motion at Yucca Mountain, Nevada. Milestone 
SP32IM3, September 23, 1998. Three volumes. Las Vegas, Nevada: CRWMS 
M&O. ACC: MOL.19981207.0393. 
105162 National Research Council. 1992. Ground Water at Yucca Mountain, How High Can 
It Rise? Final Report of the Panel on Coupled Hydrologic/Tectonic/Hydrothermal 
Systems at Yucca Mountain. Washington, D.C.: National Academy Press. TIC: 
204931. 
105347 CRWMS M&O 1998. Synthesis of Volcanism Studies for the Yucca Mountain Site 
Characterization Project. Deliverable 3781MR1. Las Vegas, Nevada: CRWMS 
M&O. ACC: MOL.19990511.0400. 
106634 Ratcliff, C.D.; Geissman, J.W.; Perry, F.V.; Crowe, B.M.; and Zeitler, P.K. 1994. 
"Paleomagnetic Record of a Geomagnetic Field Reversal from Late Miocene Mafic 
Intrusions, Southern Nevada." Science, 266, 412-416. Washington, D.C.: American 
Association for the Advancement of Science. TIC: 234818. 
107425 French, D.E. 2000. Hydrocarbon Assessment of the Yucca Mountain Vicinity, Nye 
County, Nevada. Open-File Report 2000-2. [Reno, Nevada]: Nevada Bureau of 
Mines and Geology. ACC: MOL.20000609.0298. 
108865 Whelan, J.F.; Moscati, R.J.; Roedder, E.; and Marshall, B.D. 1998. "Secondary 
Mineral Evidence of Past Water Table Changes at Yucca Mountain, Nevada." High-
Level Radioactive Waste Management, Proceedings of the Eighth International 
Conference, Las Vegas, Nevada, May 11-14, 1998. Pages 178-181. La Grange Park, 
Illinois: American Nuclear Society. TIC: 237082. 
118941 Ferrill, D.A.; Winterle, J.; Wittmeyer, G.; Sims, D.; Colton, S.; Armstrong, A.; and 
Morris, A.P. 1999. "Stressed Rock Strains Groundwater at Yucca Mountain, 
Nevada." GSA Today, 9, (5), 1-8. Boulder, Colorado: Geological Society of 
America. TIC: 246229. 
129867 Viswanath, D.S. and Natarajan, G. 1989. Data Book on the Viscosity of Liquids. 
714-715. New York, New York: Hemisphere Publishing Corporation. TIC: 
247513. 
142321 CRWMS M&O 2000. Characterize Framework for Seismicity and Structural 
Deformation at Yucca Mountain, Nevada. ANL-CRW-GS-000003 REV 00. Las 
Vegas, Nevada: CRWMS M&O. ACC: MOL.20000510.0175. 

145287 Streeter, V.L. and Wylie, E.B. 1979. Fluid Mechanics. 7th Edition. New York, 
New York: McGraw-Hill. TIC: 4819. 
145412 GS980908312322.008. Field, Chemical, and Isotopic Data from Precipitation 
Sample Collected Behind Service Station in Area 25 and Ground Water Samples 
Collected at Boreholes UE-25 C #2, UE-25 C #3, USW UZ-14, UE-25 WT #3, UE-
25 WT #17, and USW WT-24, 10/06/97 to 07/01/98. Submittal date: 09/15/1998. 
149611 GS931100121347.007. Selected Ground-Water Data for Yucca Mountain Region, 
Southern Nevada and Eastern California, Through December 1992. Submittal date: 
11/30/1993. 
149850 Mongano, G.S.; Singleton, W.L.; Moyer, T.C.; Beason, S.C.; Eatman, G.L.W.; Albin, 
A.L.; and Lung, R.C. 1999. Geology of the ECRB Cross Drift - Exploratory Studies 
Facility, Yucca Mountain Project, Yucca Mountain, Nevada. [Deliverable 
SPG42GM3]. Denver, Colorado: U.S. Geological Survey. ACC: 
MOL.20000324.0614. 
151945 CRWMS M&O 2000. Yucca Mountain Site Description. TDR-CRW-GS-000001 
REV 01 ICN 01. Las Vegas, Nevada: CRWMS M&O. ACC: 
MOL.20001003.0111. 
153246 CRWMS M&O 2000. Total System Performance Assessment for the Site 
Recommendation. TDR-WIS-PA-000001 REV 00 ICN 01. Las Vegas, Nevada: 
CRWMS M&O. ACC: MOL.20001220.0045. 
154365 BSC (Bechtel SAIC Company) 2001. The Development of Information Catalogued 
in REV00 of the YMP FEP Database. TDR-WIS-MD-000003 REV 00 ICN 01. Las 
Vegas, Nevada: Bechtel SAIC Company. ACC: MOL.20010301.0237. 
154431 BSC (Bechtel SAIC Company) 2001. Dissolved Concentration Limits for Certain 
Radioactive Elements. CAL-WIS-MD-000012 REV 00. Las Vegas, Nevada: 
Bechtel SAIC Company. ACC: MOL.20010806.0071. 
154734 GS010308312322.003. Field, Chemical and Isotopic Data from Wells in Yucca 
Mountain Area, Nye County, Nevada, Collected Between 12/11/98 and 11/15/99. 
Submittal date: 03/29/2000. 
155270 GS000808312312.007. Ground-Water Altitudes from Manual Depth-to-Water 
Measurements at Various Boreholes November 1998 through December 1999. 
Submittal date: 08/21/2000. 
156269 Bear, J. 1972. Dynamics of Fluids in Porous Media. Environmental Science Series. 
Biswas, A.K., ed. New York, New York: Elsevier. TIC: 217356. 

158966 BSC (Bechtel SAIC Company) 2002. The Enhanced Plan for Features, Events, and 
Processes (FEPs) at Yucca Mountain. TDR-WIS-PA-000005 REV 00. Las Vegas, 
Nevada: Bechtel SAIC Company. ACC: MOL.20020417.0385. 
160928 Carter Krogh, K.E. and Valentine, G.A. 1996. Structural Control on Basaltic Dike 
and Sill Emplacement, Paiute Ridge Mafic Intrusion Complex, Southern Nevada. 
LA-13157-MS. Los Alamos, New Mexico: Los Alamos National Laboratories. 
ACC: MOL.20030828.0138. 
161725 LANL (Los Alamos National Laboratory) 2003. Software Code: FEHM. V2.20. 
SUN, PC. 10086-2.20-00. 
161851 BSC (Bechtel SAIC Company) 2003. Number of Waste Packages Hit by Igneous 
Intrusion. ANL-MGR-GS-000003 REV 00C. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: MOL.20030711.0099. TBV-5399 
161961 BSC (Bechtel SAIC Company) 2003. Initial Radionuclide Inventories. ANL-WIS-
MD-000020 REV 00. Las Vegas, Nevada: Bechtel SAIC Company. ACC: 
DOC.20031110.0002. 
162729 BSC (Bechtel SAIC Company) 2003. Saturated Zone Colloid Transport. ANL-
NBS-HS-000031 REV 01. Las Vegas, Nevada: Bechtel SAIC Company. ACC: 
DOC.20030916.0008. 
163344 SNL (Sandia National Laboratories) 2003. Software Code: SZ_Convolute. V2.2. 
PC, Windows 2000. 10207-2.2-00. 
163417 Kuiper, L 1991. "Water-table Rise due to Magma Intrusion beneath Yucca 
Mountain." EOS, Transactions. 72, Numbers 1-26, 121. Washington, DC: 
American Geophysical Union. 
163555 GS010908312332.002. Borehole Data from Water-Level Data Analysis for the 
Saturated Zone Site-Scale Flow and Transport Model. Submittal date: 10/02/2001. 
163769 BSC (Bechtel SAIC Company) 2003. Characterize Framework for Igneous Activity 
at Yucca Mountain, Nevada. ANL-MGR-GS-000001 REV 01. Las Vegas, Nevada: 
Bechtel SAIC Company. ACC: MOL.20040106.003. 
164403 BSC (Bechtel SAIC Company) 2003. Nominal Performance Biosphere Dose 
Conversion Factor Analysis. ANL-MGR-MD-000009 REV 02. Las Vegas, Nevada: 
Bechtel SAIC Company. ACC: DOC.20030728.0008. 
164527 MO0307SEPFEPS4.000. LA FEP List. Submittal date: 07/31/2003. 

164648 BSC (Bechtel SAIC Company) 2001. Recharge and Lateral Groundwater Flow 
Boundary Conditions for the Saturated Zone Site-Scale Flow and Transport Model. 
ANL-NBS-MD-000010 REV 00 ICN 01. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: MOL.20020129.0093. 
164873 BSC (Bechtel SAIC Company) 2003. Features, Events, and Processes in UZ Flow 
and Transport. ANL-NBS-MD-000001 REV 02A. Las Vegas, Nevada: Bechtel 
SAIC Company. ACC: MOL.20031016.0004. TBV-5483 
165069 Johnson, Michael J., Charles J. Mayers, and Brian J. Andraski 2002. Selected 
Micrometerological and Soil-Moisture Data at Amargosa Desert Research Site in 
Nye County Near Beatty, Nevada, 1998-2000. USGS Open-File Report 02-348. 
Carson City, NV: U.S. Geological Survey. 
165176 USGS (U.S. Geological Survey) 2003. Errata, Hydrogeologic Framework Model for 
the Saturated-Zone Site-Scale Flow and Transport Model. ANL-NBS-HS-000033 
REV 00 ICN 02. Denver, Colorado: U.S. Geological Survey. ACC: 
DOC.20030319.0002; MOL.20011112.0070. 
165394 Freeze, G. 2003. KTI Letter Report, Response to Additional Information Needs on 
TSPAI 2.05 and TSPAI 2.06. REG-WIS-PA-000003 REV 00 ICN 04. Las Vegas, 
Nevada: Bechtel SAIC Company. ACC: DOC.20030825.0003. 
165843 BSC (Bechtel SAIC Company) 2003. Evaluation of Features, Events, and Processes 
(FEP) for the Biosphere Model. ANL-MGR-MD-000011 REV 03. Las Vegas, 
Nevada: Bechtel SAIC Company. ACC: DOC.20031014.0008. 
165880 MO0310INPDEFEP.000. Pre-1999 USGS and Los Alamos Field Observations at 
Yucca Mountain, Paiute Ridge, and Nevada Test Site Used to Exclude DE FEPS. 
Submittal date: 10/16/2003. 
166034 BSC (Bechtel SAIC Company) 2003. Technical Work Plan for: Saturated Zone 
Flow and Transport Modeling and Testing. TWP-NBS-MD-000002 REV 01 ICN 
01. Las Vegas, Nevada: Bechtel SAIC Company. ACC: DOC.20031203.0002. 
166162 Henriet, J.P. and Mienert, J. (editors) 1998. "Gas Hydrates- Relevance to World 
Margin Stability and Climate Change" Geological Society Special Publication No 
137, . London, England: The Geological Society of London. 
166262 BSC (Bechtel SAIC Company) 2003. Site-Scale Saturated Zone Flow Model. MDL-
NBS-HS-000011 REV 01. Las Vegas, Nevada: Bechtel SAIC Company. ACC: 
DOC.20040126.0004. 

166335 Arnold, Bill W., Hubao Zhang and Alva M. Parsons 2000. "Effective-Porosity and 
Dual-Porosity Approaches to Solute Transport in the Saturated Zone at Yucca 
Mountain: Implications for Repository Performance Assessment." Dynamics of 
Fluids in Fractured Rock [Papers Selected from a Symposium held at Ernest Orlando 
Lawrence Berkeley National Laboratory on February 10-12, 1999].. Faybishenko, 
B.; Witherspoon, A.; and Benson, S.M.. Geophysical Monograph 122., 313-322. 
Washington, D.C, D.C.: American Geophysical Union. 
166498 BSC (Bechtel SAIC Company) 2003. Mountain-Scale Coupled Processes 
(TH/THC/THM). MDL-NBS-HS-000007 REV 01. Las Vegas, Nevada: Bechtel 
SAIC Company. ACC: DOC.200. 31216.0003. 
166845 BSC (Bechtel SAIC Company) 2003. Waste Form and In-Drift Colloids-Associated 
Radionuclide Concentrations: Abstraction and Summary. MDL-EBS-PA-000004 
REV 00 ICN 01. Las Vegas, Nevada: Bechtel SAIC Company. ACC: 
DOC.20031222.0012. 
167208 BSC (Bechtel SAIC Company) 2003. Site-Scale Saturated Zone Transport. MDL-
NBS-HS-000010 REV 01. Las Vegas, NV: Bechtel SAIC Company. ACC: 
DOC.20040126.0003. 
167209 BSC (Bechtel SAIC Company) 2003. Saturated Zone In-Situ Testing. ANL-NBS-
HS-000039 REV 00. Las Vegas, Nevada: Bechtel SAIC Company. ACC: 
DOC.20040128.0003. 
167211 BSC (Bechtel SAIC Company) 2003. Geochemical and Isotopic Constraints on 
Groundwater Flow Directions and Magnitudes, Mixing, and Recharge at Yucca 
Mountain. ANL-NBS-HS-000021 REV 01. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: MOL.20030604.0164. 
167651 BSC (Bechtel SAIC Company) 2003. Saturated Zone Flow and Transport Model 
Abstraction. MDL-NBS-HS-000021 REV 01. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: DOC.20040128.0001. 
167720 BSC (Bechtel SAIC Company) 2004. Errata for Features, Events, and Processes: 
Disruptive Events. ANL-WIS-MD-000005 REV 001. Las Vegas, Nevada: Bechtel 
SAIC Company. ACC: DOC.20031212.0005; DOC.20040209.0001. 
167914 Economy, K. 2004. "Adoption of Licensing Position - Paper - LP-028 DRAFT 
REV0F - Recycling of Radionuclides at the Location of the Reasonably Maximally 
Exposed Individual in the Screening Argument for the SZ FEP 1.4.07.03.0A 
(Recycling of Accumulated Radionuclides from Soils to Groundwater)." 
Memorandum from K. Economy (John Hart and Associates) to S. Kuzio (SNL), 
March 9, 2004, with attachment. ACC: MOL.20040301.0190; 
MOL.20040311.0001. 

167961 USGS (U.S. Geological Survey) 2003. Errata for Future Climate Analysis. ANL-
NBS-GS-000008 REV 00 ICN 01. Denver, Colorado: U.S. Geological Survey. 
ACC: MOL.20011107.0004; DOC.20031015.0003. 
168473 USGS (U.S. Geological Survey) 2004. Water-Level Data Analysis for the Saturated 
Zone Site-Scale Flow and Transport Model, 001 Errata 001 002. ANL-NBS-HS-
000034 REV 01. Denver, Colorado: U.S. Geological Survey. ACC: MOL. 
20020209.0058; MOL.20020917.0136; DOC.20040303.0006 
8.2 PROCEDURES AND GUIDANCE 
159475 DOE (U.S. Department of Energy) 2002. Quality Assurance Requirements and 
Description. DOE/RW-0333P, Rev. 12. Washington, D.C.: U.S. Department of 
Energy, Office of Civilian Radioactive Waste Management. ACC: 
MOL.20020819.0387. 
159604 AP-2.27Q, Rev. 0, ICN 0. Planning for Science Activities. Washington, 
D.C.: U.S. Department of Energy, Office of Civilian Radioactive Waste 
Management. ACC: MOL.20020701.0184. 
160313 BSC (Bechtel SAIC Company) 2002. Scientific Processes Guidelines Manual. MIS-
WIS-MD-000001 REV 01. Las Vegas, Nevada: Bechtel SAIC Company. ACC: 
MOL.20020923.0176. 
161770 Canori, G.F. and Leitner, M.M. 2003. Project Requirements Document. TER-MGR-
MD-000001 REV 01. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20030404.0003. 
163274 NRC (U.S. Nuclear Regulatory Commission) 2003. Yucca Mountain Review Plan, 
Final Report. NUREG-1804, Rev. 2. Washington, D.C.: U.S. Nuclear Regulatory 
Commission, Office of Nuclear Material Safety and Safeguards. TIC: 254568. 
163414 AP-3.15Q, Rev. 4, ICN 1. Managing Technical Product Inputs. Washington, D.C.: 
U.S. Department of Energy, Office of Civilian Radioactive Waste Management. 
ACC: DOC.20030512.0006. 
164786 AP-2.22Q, Rev. 1, ICN 0. Classification Analyses and Maintenance of the Q-List. 
Washington, D.C.: U.S. Department of Energy, Office of Civilian Radioactive Waste 
Management. ACC: DOC.20030807.0002. 
165179 BSC 2003. Q-List. TDR-MGR-RL-000005. Las Vegas, Nevada: BSC. 
ACC: DOC.20030930.0002. 
167992 AP-SIII.9Q, Rev. 1, ICN 03. Scientific Analyses. Washington, D.C.: U.S. 
Department of Energy, Office of Civilian Radioactive Waste Management. 
ACC: DOC.20040301.0002. 

8.3 CODES AND REGULATIONS 
100975 DOE (U.S. Department of Energy) 1996. Title 40 CFR Part 191 Compliance 
Certification Application for the Waste Isolation Pilot Plant. DOE/CAO-1996-2184. 
Twenty-one volumes. Carlsbad, New Mexico: U.S. Department of Energy, Carlsbad 
Area Office. TIC: 240511. 
105065 64 FR 46976. Environmental Radiation Protection Standards for Yucca Mountain, 
Nevada. Proposed rule 40 CFR Part 197. Readily available. 
156605 10 CFR 63. Energy: Disposal of High-Level Radioactive Wastes in a Geologic 
Repository at Yucca Mountain, Nevada. Readily available. 
156671 66 FR 55732. Disposal of High-Level Radioactive Wastes in a Proposed Geologic 
Repository at Yucca Mountain, NV. Final Rule 10 CFR Part 63.