Features, Events, and Processes in SZ Flow and Transport REV 03, ICN 00
 
ANL-NBS-MD-000002 

November 2004

1. PURPOSE 
This analysis report evaluates and documents the inclusion or exclusion of the saturated zone 
(SZ) features, events, and processes (FEPs) with respect to modeling used to support the total 
system performance assessment (TSPA) for license application (LA) of a nuclear waste 
repository at Yucca Mountain, Nevada. 
A screening decision, either Included or Excluded, is given for each FEP along with the technical 
basis for the decision. This information is required by the U.S. Nuclear Regulatory Commission 
(NRC) at 10 CFR 63.114 (d), (e), (f) (DIRS 156605). 
This scientific report focuses on FEP analysis of flow and transport issues relevant to the SZ 
(e.g., fracture flow in volcanic units, anisotropy, radionuclide transport on colloids, etc.) to be 
considered in the TSPA model for the LA. For included FEPs, this analysis summarizes the 
implementation of the FEP in TSPA-LA (i.e., how the FEP is included). For excluded FEPs, this 
analysis provides the technical basis for exclusion from TSPA-LA (i.e., why the FEP is 
excluded). 
The initial version of this report (Revision 00) was developed to support the TSPA for site 
recommendation. The current revision supports the TSPA-LA. 
1.1 PLANNING AND DOCUMENTATION 
This scientific report is governed by Technical Work Plan for: Regulatory Integration Team 
Revision of Features, Events, and Processes (FEPS) Analysis Reports Integration (BSC 2004 
[DIRS 170408]). 
1.2 SCOPE 
The scope of this report is to describe, evaluate, and document screening decisions and technical 
bases for the SZ FEPs for the TSPA-LA. A TSPA-LA disposition is provided for FEPs included 
in the TSPA-LA; the disposition is a consolidated summary of how the FEP has been included 
and addressed in the TSPA-LA model, based on supporting analysis and model reports that 
describe the inclusion of the FEP. The report also provides a list, or reference roadmap, of the 
specific supporting technical reports that provide more detailed discussions of the FEP. 
For FEPs that are excluded from the TSPA-LA, a screening argument identifies the basis for the 
exclusion decision (i.e., low probability, low consequence, or by regulation) and discusses the 
technical basis that supports that decision. The report also provides appropriate references to 
Project and non-Project information that supports the exclusion. 
In cases where a FEP covers multiple technical areas and is shared with other FEP reports, only a 
partial technical basis for the screening decision as it relates to SZ concerns is provided. The full 
technical basis for these shared FEPs is addressed, collectively, by all of the sharing FEP reports. 
This information is provided in Section 6.2 and subsequent sections. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 1-2 November 2004 
An overview of the Yucca Mountain Project (YMP) FEP analysis and scenario development 
process is available in The Development of the Total System Performance Assessment-License 
Application Features, Events, and Processes (BSC 2004 [DIRS 168706], Sections 2.4, 3, and 4), 
describing the TSPA-LA FEP identification and screening process. As part of that process, the 
TSPA-LA FEP list (DTN: MO0407SEPFEPLA.000 [DIRS 170760]) was developed. This data 
tracking number (DTN) was used as an initial input to the SZ FEP analysis. The list of SZ 
TSPA-LA FEPs (Table 1.2-1) was derived from DTN: MO0407SEPFEPLA.000 (DIRS 170760) 
with subsequent modifications to the FEP list, FEP names, and/or FEP descriptions. These 
modifications are documented in the FEP History File in the FEP database (BSC 2004 
[DIRS 168706], Table 6-2) and will be incorporated into a subsequent revision of the TSPA-LA 
FEP list (Section 7). Table 1.2-1 also includes the designation of shared FEPs. 
Direct inputs supporting the screening decisions are listed in Section 4. The individual FEP 
discussions providing identification (FEP number, name, and description) and screening 
(screening decision, screening argument or TSPA disposition) information are in Section 6.2. 
Table 1.2-1. SZ FEPs for the TSPA-LA 
FEP Number FEP Name 
Section Discussed in 
This Document 
FEP Shared with Other 
Disciplines 
1.2.02.01.0A Fractures 6.2.1 UZ 
1.2.02.02.0A Faults 6.2.2 UZ 
1.2.04.02.0A Igneous activity changes rock 
properties 
6.2.3 DE 
UZ 
1.2.04.07.0B Ash redistribution in groundwater 6.2.4 N/A 
1.2.06.00.0A Hydrothermal activity 6.2.5 UZ 
1.2.09.02.0A Large-scale dissolution 6.2.6 UZ 
1.2.10.01.0A Hydrologic response to seismic 
activity 
6.2.7 DE 
UZ 
1.2.10.02.0A Hydrologic response to igneous 
activity 
6.2.8 DE 
UZ 
1.3.07.01.0A Water table decline 6.2.9 UZ 
1.3.07.02.0A Water table rise affects SZ 6.2.10 
Bio 
1.4.07.01.0A Water management activities 6.2.11 Bio 
1.4.07.02.0A Wells 6.2.12 Bio 
1.4.07.03.0A Recycling of accumulated 
radionuclides from soils to 
groundwater 
6.2.46 N/A 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 1-3 November 2004 
Table 1.2-1. SZ FEPs for the TSPA-LA (Continued) 
FEP Number FEP Name 
Section Discussed in 
This Document 
FEP Shared with Other 
Disciplines 
2.1.09.21.0B Transport of particles larger than 
colloids in the SZ 
6.2.13 N/A 
2.2.03.01.0A Stratigraphy 6.2.14 UZ 
2.2.03.02.0A Rock properties of host rock and 
other units 
6.2.15 UZ 
2.2.06.01.0A Seismic activity changes porosity and 
permeability of rock 
6.2.16 DE 
UZ 
2.2.06.02.0A Seismic activity changes porosity and 
permeability of faults 
6.2.17 DE 
UZ 
2.2.06.02.0B Seismic activity changes porosity and 
permeability of fractures 
6.2.18 DE 
UZ 
2.2.07.12.0A Saturated groundwater flow in the 
geosphere 
6.2.19 N/A 
2.2.07.13.0A Water-conducting features in the SZ 6.2.20 N/A 
2.2.07.14.0A Chemically-induced density effects on 
groundwater flow 
6.2.21 N/A 
2.2.07.15.0A Advection and dispersion in the SZ 6.2.22 N/A 
2.2.07.16.0A Dilution of radionuclides in 
groundwater 
6.2.23 UZ 
2.2.07.17.0A Diffusion in the SZ 6.2.24 N/A 
2.2.08.01.0A Chemical characteristics of 
groundwater in the SZ 
6.2.25 
Bio 
2.2.08.03.0A Geochemical interactions and 
evolution in the SZ 
6.2.26 N/A 
2.2.08.06.0A Complexation in the SZ 6.2.27 N/A 
2.2.08.07.0A Radionuclide solubility limits in the SZ 6.2.28 N/A 
2.2.08.08.0A Matrix diffusion in the SZ 6.2.29 N/A 
2.2.08.09.0A Sorption in the SZ 6.2.30 N/A 
2.2.08.10.0A Colloidal transport in the SZ 6.2.31 N/A 
2.2.08.11.0A Groundwater discharge to surface 
within the reference biosphere 
6.2.32 Bio 
2.2.09.01.0A Microbial activity in the SZ 6.2.33 N/A 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 1-4 November 2004 
Table 1.2-1. SZ FEPs for the TSPA-LA (Continued) 
FEP Number FEP Name 
Section Discussed in 
This Document 
FEP Shared with Other 
Disciplines 
2.2.10.02.0A Thermal convection cell develops in 
SZ 
6.2.34 N/A 
2.2.10.03.0A Natural geothermal effects on flow in 
the SZ 
6.2.35 N/A 
2.2.10.04.0A Thermo-mechanical stresses alter 
characteristics of fractures near 
repository 
6.2.36 UZ 
2.2.10.04.0B Thermo-mechanical stresses alter 
characteristics of faults near 
repository 
6.2.37 UZ 
2.2.10.05.0A Thermo-mechanical stresses alter 
characteristics of rocks above and 
below the repository 
6.2.38 UZ 
2.2.10.08.0A Thermo-chemical alteration in the SZ 
(solubility, speciation, phase 
changes, precipitation/dissolution) 
6.2.39 N/A 
2.2.10.13.0A Repository-induced thermal effects 
on flow in the SZ 
6.2.40 N/A 
2.2.11.01.0A Gas effects in the SZ 6.2.41 N/A 
2.2.12.00.0B Undetected features in the SZ 6.2.42 N/A 
2.3.11.04.0A Groundwater discharge to surface 
outside the reference biosphere 
6.2.43 Bio 
3.1.01.01.0A Radioactive decay and ingrowth 6.2.44 Bio 
UZ 
WF 
3.2.07.01.0A Isotopic dilution 6.2.45 N/A 
Bio=biosphere; DE=disruptive event; FEP=feature, event, and process; N/A=not applicable; UZ=unsaturated zone; 
WF=waste form 
1.3 SCIENTIFIC ANALYSIS LIMITATIONS AND USE 
The intended use of this report is to provide FEP screening information for a Project-specific 
FEP database, to promote traceability and transparency for included and excluded SZ FEPs, and 
to document inclusion or exclusion of SZ FEPs within or from the TSPA-LA model. The 
following limitations apply: 
 Because other reports and controlled documents are cited as direct input, the limitations 
inherently include any limitations or constraints described in the cited reports or 
controlled documents. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 1-5 November 2004 
 In cases where FEPs are shared, the scope of this report is limited to the SZ. The full 
technical basis for the shared FEPs is addressed, collectively, by all of the sharing FEP 
reports. 
 For screening purposes, mean values of probabilities, mean amplitude of events, or mean 
value of consequences (e.g., mean time to waste package degradation) are used as a basis 
for reaching a decision to include or exclude. Mean values are determined based on the 
range and distribution of possible values. 
 The results of the FEP screening are specific to the repository design and processes for 
YMP available at the time of the TSPA-LA. Changes in direct inputs listed in 
Section 4.1, in baseline conditions used for this evaluation, or in other subsurface 
conditions will need to be evaluated to determine whether the changes are within the 
limits stated in the FEP evaluations. Engineering and design changes are subject to 
evaluation to determine whether there are any adverse impacts to safety, as codified at 
10 CFR 63.73 and in Subparts F and G (DIRS 156605). See also the requirements at 
10 CFR 63.44. 

Features, Events, and Processes in SZ Flow and Transport 
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Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 2-1 November 2004 
2. QUALITY ASSURANCE 
Development of this report and supporting analyses are subject to the U.S. Department of Energy 
(DOE) Office of Civilian Radioactive Waste Management quality assurance program as 
indicated in Technical Work Plan For: Regulatory Integration Team Revision of Features, 
Events, and Processes (FEPs) Analysis Reports Integration (BSC 2004 [DIRS 170408], 
Section 8.1). Approved quality assurance procedures identified in Section 4.1 of the technical 
work plan have been used to conduct and document the activities described in this report. The 
documentation has been prepared according to AP-SIII.9Q, Scientific Analyses, and in 
accordance with related procedures and guidance documents as outlined in the technical work 
plan. Section 8.4 of the plan identifies applicable controls for the electronic management of data 
during the analysis and documentation activities. 
The report contributes to the analysis and modeling used to support performance assessment. 
The SZ FEPs involve the investigations of items or barriers on the Q-List (BSC 2004 
[DIRS 168361]) and have the potential to affect the calculation of the performance of the natural 
barriers included on the Q-List. However, the SZ FEPs themselves do not qualify as Q-List 
items. The evaluations and conclusions do not directly impact engineered features important to 
safety, as defined in AP-2.22Q, Classification Analyses and Maintenance of the Q-List. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 2-2 November 2004 
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Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 3-1 November 2004 
3. USE OF SOFTWARE 
No computational software, other than the exempt software listed below, was used in preparation 
of this report; therefore, this analysis is not subject to software controls. The analyses and 
arguments are based on guidance and regulatory requirements, on results of analyses presented 
and documented in other reports, or on other technical literature. Software and models used in 
the supporting documents are cited for traceability and transparency purposes but were not used 
in the development of this report. 
Only commercially available software, which is exempt from Yucca Mountain qualification 
procedures, was used. Sigma Plot, Scientific Graphic Software, V3.06, Jandel Corporation, and 
Microsoft Excel 97 Software Release-1 are commercial software packages used to display the 
data visually using only standard, built-in mathematical functions. SigmaPlot also is used to plot 
data used in 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. Microsoft Word 2000 used for word processing is exempt from qualification 
requirements, in accordance with LP-SI.11Q-BSC, Software Management. 

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ANL-NBS-MD-000002 REV 03 3-2 November 2004 
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Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-1 November 2004 
4. INPUTS 
AP-3.15Q, Managing Technical Product Inputs, categorizes technical product input usage as 
either direct or indirect. A direct input is used to develop the results or conclusions in a technical 
product. An indirect input is used to provide additional information that is not used in the 
development of results or conclusions. 
Section 4.1 identifies the direct inputs used in this FEP report. The direct inputs were obtained 
from controlled source documents and other appropriate sources in accordance with the 
controlling procedure AP-3.15Q. Section 4.2 identifies the FEP screening criteria described in 
10 CFR Part 63 (DIRS 156605), along with the regulatory derived FEP screening criteria. 
Section 4.3 discusses codes, standards, and regulations. 
4.1 DIRECT INPUTS 
The LA FEP List (DTN: MO0407SEPFEPLA.000 [DIRS 170760]) was used as a direct input to 
provide the initial list of SZ FEPs for screening in this report. The LA FEP List identifies a FEP 
report or a set of sharing FEP reports for each FEP. Subsequent additions to or changes from the 
FEP list (numbers, names, or descriptions) are reflected in the information provided in 
Section 6.2 and can be traced through the FEP History File in the FEP database (BSC 2004 
[DIRS 168706], Table 6-2). Other direct inputs used for the FEP screening analysis are listed in 
Table 4.1-1 for the included FEPs and Table 4.1-2 for the excluded FEPs. 
The direct inputs are appropriate for use, as discussed below: 
 Established facts: 
 Eckerman and Ryman (1993 [DIRS 107684], Table A-1) present half-life values for 
selected radioisotopes. The half-life value, which is constant for any particular 
isotope, is the time required for one-half the atoms initially present to disintegrate. 
 Domenico and Schwartz (1990 [DIRS 100569], Chapter 14, Equation 14.11) present 
the equation for radioactive decay. The equation is a mathematical exponential 
expression of the decay of radioactive isotopes. 
 Viswanath and Natarajan (1989 [DIRS 129867], p. 715) present the viscosity of water 
value. This is a published engineering handbook containing viscosity tables relating 
to liquids. 
 Streeter and Wylie (1979 [DIRS 145287], p. 534) present the density of water value. 
This is a published engineering handbook containing data relating to fluid mechanics. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-2 November 2004 
 Site characterization information: 
Information on site characterization boreholes is provided in inputs 
DTN: GS010308312322.003 (DIRS 154734) and DTN: GS010908312332.002 
(DIRS 163555). Information on site characterization regarding the number of waste 
packages brought to the surface by a single volcanic event is provided in 
DTN: SN0402T0503303.004 (DIRS 167515). Information on site characterization on 
the dose conversion factors for selected radionuclides is provided in 
DTN: MO0307MWDNPBDC.001 (DIRS 164615). DTN: LA0407DK831811.001 
(DIRS 170768) provides the dimensions of basaltic dikes near Yucca Mountain. This is 
the best available information pertaining to these topics for the site characterization 
evaluated in Sections 6.2.3, 6.2.4, 6.2.33, and 6.2.41. 
 Data qualified within this report: 
Unqualified data used as direct input for this report are qualified in Appendix A, where 
their appropriateness for the intended purpose is documented. 
 All remaining direct inputs: 
All remaining direct inputs are from model and analysis reports qualified for use to 
support the Yucca Mountain license application. The information used as inputs from 
these reports pertains directly to the exclusion arguments in Section 6.2 and, therefore, 
are suitable for their intended use. 
The regulations (10 CFR Part 63 [DIRS 156605]) provide direct inputs to the FEP screening 
process. By specifying characteristics, concepts, and definitions, the regulations serve as 
de facto inputs used for screening FEPs. The regulatory definitions and elucidation of the 
regulatory concepts pertaining to the reference biosphere, geologic setting, reasonably maximally 
exposed individual (RMEI), and human intrusion are explained in detail in Section 4.1.3 of The 
Development of the Total System Performance Assessment-License Application Features, Events, 
and Processes (BSC 2004 [DIRS 168706]). For the SZ FEPs, the inputs of particular interest 
include the reference biosphere, the geologic setting, and the RMEI. Specific direct inputs from 
the regulations addressing these concepts are listed in Table 4.1-3. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-3 November 2004 
Table 4.1-1. Inputs for Included FEPs 
Reference 
Database 
Number Input Source Direct Use In Description 
Input 
Category 
DIRS 
170006 
BSC 2004. Saturated Zone Colloid Transport. 
ANL-NBS-HS-000031 REV 02. Las Vegas, 
Nevada: Bechtel SAIC Company. 
ACC: DOC.20041008.0007. 
Section 7 Section 6.2.31 Parameter distributions related to reversible sorption 
onto colloids are based on field observations and 
laboratory experiments performed on colloids and 
geochemical conditions found in the Yucca Mountain 
vicinity. 
Data 
DIRS 
170008 
BSC 2004. Hydrogeologic Framework Model 
for the Saturated Zone Site-Scale Flow and 
Transport Model. MDL-NBS-HS-000024, 
Rev. 00. Las Vegas, Nevada: Bechtel SAIC 
Company. 
Section 7 Section 6.2.2 Representation of faults and other hydrologic 
features affecting SZ flow are developed in the 
hydrogeologic framework model. 
Data 
DIRS 
170014 
BSC 2004. Probability Distribution for Flowing 
Interval Spacing. ANL-NBS-MD-000003, 
Rev. 01. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: DOC.20040923.0003. 
Entire Section 6.2.1 Only a subset of fractures transmits flow in the SZ. Data 
Appendix E 
Figures E-1 and 
E-2 
Section 6.2.10 (1) Conservative and nonconservative tracer 
breakthrough curves for explicitly modeling 
simulations of a 100 m rise in water table. (2) BTC 
trailing edges for the alternative model domain are 
well over an order of magnitude greater compared to 
those derived using a flux multiplier. 
Data 
Appendix E, 
Section E 1 
Section 6.2.10 An alternative SZ model allows the water table to be 
100 m higher than present conditions under the 
repository footprint. 
Data 
Sections 6.3 
and 6.4 
Section 6.2.22 Advection and dispersion of dissolved radionuclides 
are explicitly included in the conceptual and 
mathematical models for TSPA-LA. 
Data 
Section 6.4.2.1 Section 6.2.24 The dispersion tensor is the sum of the mechanical 
dispersion tensor for the flow system and the 
coefficient of molecular diffusion in porous media. 
Data 
Section 6.4.2.3 Section 6.2.24 The effects of molecular diffusion are explicitly 
included in the SZ flow and transport model by 
numerically including it in the displacement matrix. 
Data 
DIRS 
170036 
BSC 2004. Site-Scale Saturated Zone 
Transport. MDL-NBS-H-000010, Rev. 02. 
Las Vegas, Nevada: Bechtel SAIC Company. 
Table 4-2 Section 6.2.24 1) the lower limit for longitudinal dispersivity is 0.1 m, 
2) the upper limit of effective diffusion coefficient in 
the volcanics is 5x10-10 m2/s. 
Data 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-4 November 2004 
Table 4.1-1. Inputs for Included FEPs (Continued) 
Reference 
Database 
Number Input Source Direct Use In Description 
Input 
Category 
Table 4-2 
(footnote) 
Section 6.2.24 Mean specific discharge value of 0.67 m/year in the 
site-scale SZ flow model. 
Data 
Equations 56 
(a, b) and 57 
Section 6.2.25 Equations 56 (a, b) and 57 (of said document) 
describe SZ radionuclide retarded transport via the 
distribution coefficients and the retardation factors 
Data 
Appendix A Section 6.2.25 Appropriate ranges and distributions of values for Kd 
are chosen based on laboratory and field studies. 
Data 
Sections 6.3 
and 6.4 
Section 6.2.27 Inorganic complexing agents (dominant in the SZ) 
and some organic complexing agents (such as 
humic and fulvic acids) are included in the model. 
Data 
Sections 
6.4.2.4.1 and 
6.4.2.5 
Section 6.2.27 The sorption coefficients Kd and Kc enter the SZ 
transport model via Equations 56a, 56b, 57, 76, 77, 
and 78 (in the SZ transport model). 
Data 
Section 
6.4.2.4.1 
Section 6.2.29 Matrix diffusion is included in Equations 56 and 57 
(in the SZ transport model). 
Data 
Section 
6.4.2.4.1 
Section 6.2.30 Sorption can occur within flowing zones due to the 
rubbleized matrix, and this effect is included in the 
retardation coefficient R in Equation 56a of subject 
report (in the SZ transport model). 
Data 
Equation 77 Section 6.2.30 Sorption in the alluvium is described in Equation 77 
of subject report (in the SZ transport model). 
Data 
Appendix A, 
Section A2 
Section 6.2.30 Kd distributions adopted in the SZ transport model 
encompass the potential nonlinear behavior of the 
sorption processes. 
Data 
Appendix A, 
Section A8 
Section 6.2.30 Alluvium Kd values are slightly higher than those for 
the volcanic units. 
Data 
DIRS 
170036 
(Continued) 
BSC 2004. Site-Scale Saturated Zone 
Transport. MDL-NBS-HS-000010, Rev. 02. 
Las Vegas, Nevada: Bechtel SAIC Company 
(Continued). 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-5 November 2004 
Table 4.1-1. Inputs for Included FEPs (Continued) 
Reference 
Database 
Number Input Source Direct Use In Description 
Input 
Category 
Sections 6.3.3, 
6.5.1, and 8.3.2 
Section 6.2.1 Modeled groundwater flow through fractures in the 
volcanic units uses an effective continuum approach. 
Data 
Section 8.3.1 Section 6.2.1 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. 
Data 
Sections 6.3.2, 
6.3.2.10, and 
6.5.3.1 
Table 6-6 
Section 6.2.2 The flow properties for the hydrologic framework 
model, representing faults and other hydrologic 
features, are developed in the SZ site-scale flow 
model; fault categories are based on hydrological 
impact on SZ flow path and distributions; list of 
modeled faults. 
Data 
Section 6.4.5.1 Sections 
6.2.10 and 
6.2.25 
Approximate maximum elevation water table could 
rise below repository footprint because of wetter 
climatic conditions. 
Data 
Sections 6.5.3.1 
and 6.5.3.4 
Section 6.2.14 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. 
Data 
Section 6.5.3 Section 6.2.14 The source of the hydrogeologic subdivisions used in 
the model. 
Data 
Sections 6.3.2 
and 6.5.3.4 
Section 6.2.14 Major discontinuities between the 19 
hydrostratigraphic units are implemented by including 
17 discrete features. 
Data 
DIRS 
170037 
BSC 2004. Saturated Zone Site-Scale Flow 
Model. MDL-NBS-HS-000011, Rev. 02. 
Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: MOL.20040812.0035. 
Section 6.6.1 Sections 
6.2.12 
6.2.22 
The mean flow field is calibrated to measured 
heads. 
Data 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-6 November 2004 
Table 4.1-1. Inputs for Included FEPs (Continued) 
Reference 
Database 
Number Input Source Direct Use In Description 
Input 
Category 
Section 6.5.3.1 Section 6.2.14 Nineteen hydrogeologic units are used in the 
formulation of the base case SZ flow model. 
Data 
Section 6.5.3 Section 6.2.15 A base case permeability flow field is generated in 
the model. 
Data 
Section 6.5.3.4 
Table 6-6 
Section 6.2.15 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. 
Data 
Section 
6.3.2.10 
Section 6.2.19 Inputs into the SZ base case flow model include 
faults and fault zones and variable permeabilities 
associated with the 19 hydrostratigraphic units. 
Data 
Section 6.3.2.7 Section 6.2.19 Recharge in the SZ is modeled through underflow, 
surface flow infiltration, and UZ infiltration 
components. 
Data 
Sections 6.2 
and 6.3.1 
Section 6.2.19 Steady-state, saturated, 3-D groundwater flow within 
the Yucca Mountain vicinity is modeled 
Data 
Section 6.3.2 
Figure 6-1 
Section 6.2.19 The model domain is within the confines of the Death 
Valley groundwater basin. 
Data 
Figure 6-4 Section 6.2.20 
Figures 6.2-32 
and 6.2-3 
(1) Geologic features incorporated within the area of 
the site-scale flow and transport model. (2) The 
Solitario Canyon Splay fault serves as a groundwater 
divide. 
Data 
Section 6.3.2 
Table 6-6 
Section 6.2.20 Faults and fractures modeled through 17 discrete 
geologic features. 
Data 
Section 6.5.3.4 Section 6.2.20 Features are affected by faults, zones of mineral 
alteration, or contact zones. 
Data 
DIRS 
170037 
(Continued) 
BSC 2004. Saturated Zone Site-Scale Flow 
Model. MDL-NBS-HS-000011, Rev. 02. 
Las Vegas, Nevada: Bechtel SAIC Company 
(Continued). 
Section 6.6.2.2 Section 6.2.22 Mean specific discharge field is output from model. Data 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-7 November 2004 
Table 4.1-1. Inputs for Included FEPs (Continued) 
Reference 
Database 
Number Input Source Direct Use In Description 
Input 
Category 
Tables A-10 and 
A-11 
Section 6.2.25 Uncorrected 14C groundwater ages range from a few 
thousand years in vicinity of the Fortymile Wash to 
values greater than 15,000 years under portions of 
the Yucca Mountain. 
Data 
Section A-7.1.2 Section 6.2.25 Geochemical analysis indicates the current SZ 
groundwater under the repository and along the SZ 
transport path is paleoclimate recharge water. 
Data 
Section 6.5.3.7 Section 6.2.35 Description of the fluid-rock energy equation and 
associated sensitivities as well as how temperature 
and permeability are modeled through spatially 
variable viscosity term and implicitly through 
hydraulic heads. 
Data 
Section 7.4 Section 6.2.35 Heat transport and flow simulations were performed 
using measured temperature values in the SZ. 
Simulation results validate the implicit modeling of 
geothermal effects in SZ flow. 
Data 
DIRS 
170037 
(Continued) 
BSC 2004. Saturated Zone Site-Scale Flow 
Model. MDL-NBS-HS-000011, Rev. 02. 
Las Vegas, Nevada: Bechtel SAIC Company 
(Continued). 
Section 6.6.1 Section 6.2.42 Undetected features are implicitly modeled in the 
site-scale flow model through calibration of various 
hydrologic flow parameters to measured heads. 
Data 
Section 6.5.2.9 Sections 
6.2.1, 6.2.15, 
6.2.20, 6.2.22, 
6.2.23, 6.2.24, 
and 6.2.42 
Longitudinal dispersivity (LDISP) -Direct input for SZ 
FEP disposition for fractures, properties of host rock 
and other units, water conducting features, diffusion 
in the SZ dilution of RNs in the groundwater, 
diffusion, and undetected features. 
Data DIRS 
170042 
BSC 2004. Saturated Zone Flow and Transport 
Model Abstraction. MDL-NBS-HS-000021, 
Rev. 02. Las Vegas, Nevada: Bechtel SAIC 
Company. 
Section 6.5.2.5 Sections 
6.2.1, 6.2.15, 
6.2.20, and 
6.2.42 
Flowing interval porosity in the volcanic units 
(FPVO)- Direct input for SZ FEP disposition for 
fractures, properties of host rock and other units, 
water conducting features, and undetected features. 
Data 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-8 November 2004 
Table 4.1-1. Inputs for Included FEPs (Continued) 
Reference 
Database 
Number Input Source Direct Use In Description 
Input 
Category 
Section 6.5.2.4, Sections 
6.2.1, 6.2.15, 
6.2.20, and 
6.2.42 
Flowing interval spacing in volcanics (FISVO) -Direct 
input for SZ FEP disposition for fractures, properties 
of host rock and other units, water conducting 
features, and undetected features. 
Data 
Section 6.5.2.1 Sections 6.2.1, 
6.2.2, 6.2.14, 
6.2.15, 6.2.20, 
6.2.22, and 
6.2.42 
Groundwater specific discharge parameter (GWSPD) 
- Direct input for SZ FEP dispositions for fractures, 
faults, rock properties of host rock and other units, 
water-conducting features in the SZ, advection, and 
longitudinal, undetected features. 
Data 
Section 6.5.2.10 Sections 6.2.1, 
6.2.2, 6.2.15, 
6.2.20, 6.2.22, 
and 6.2.42 
Horizontal anisotropy in the volcanic units 
(HAVO) - Direct input for SZ FEP disposition for 
fracture, faults, properties of host rock and other 
units, water conducting features, advection and 
dispersion in the SZ, and undetected features. 
Data 
Section 6.5.2.11 
Table 6-8 
Sections 6.2.1, 
6.2.25, 6.2.30, 
and 6.2.31, 
Colloid retardation factor in the volcanics (CORVO)- 
Direct input for SZ FEP disposition for fractures, 
chemical characteristics of groundwater in the SZ 
,sorption in the SZ, colloidal transport in the SZ. 
Data 
DIRS 
170042 
(Continued) 
BSC 2004. Saturated Zone Flow and Transport 
Model Abstraction. MDL-NBS-HS-000021, 
Rev. 02. Las Vegas, Nevada: Bechtel SAIC 
Company. (Continued) 
Section 6.5.2.12 Sections 6.2.1, 
6.2.25,6.2.30, 
and 6.2.31 
(Kd_Pu_Col, Kd_Am_Col, Kd_Cs_Col) - Direct input 
for SZ FEP disposition for fractures, chemical 
characteristics of groundwater in the SZ ,sorption in 
the SZ, colloidal transport in the SZ - sorption 
coefficients onto colloids. 
Data 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-9 November 2004 
Table 4.1-1. Inputs for Included FEPs (Continued) 
Reference 
Database 
Number Input Source Direct Use In Description 
Input 
Category 
Section 6.5.2.2 Sections 
6.2.14, 6.2.15, 
and 6.2.42, 
(1) Uncertainty in the volcanic-alluvium contact zone 
is modeled in the SZ, (2) Undetected features in the 
SZ are implicitly incorporated in the transport 
abstraction model through parameter distributions 
and the probabilistic boundaries of the alluvium 
uncertainty zone. Direct input for TSPA-Dispositions 
for dispersivity, stratigraphy, rock properties, and 
undetected features. 
Data 
Section 6.5 
Table 6-5 
Section 6.2.10 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. Direct input for TSPA disposition 
for water table rise affects SZ. 
Data 
Sections 5(3) 
and 6.3.3 
Sections 
6.2.12 and 
6.2.23 
The total mass of RN crossing the 18- km boundary 
is used to determine concentration in the RMEI well 
water. - Direct input for TSPA-Dispositions for Wells 
and Dilution of Radionuclides in Groundwater. 
Data 
DIRS 
170042 
(Continued) 
BSC 2004. Saturated Zone Flow and Transport 
Model Abstraction. MDL-NBS-HS-000021, Rev. 
02. Las Vegas, Nevada: Bechtel SAIC 
Company (Continued). 
Section 6.3 and 
6.5.2 
Section 6.2.14 (1) Nineteen hydrogeologic units employed in the SZ 
flow and transport model. (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. 
Direct input for TSPA Disposition for Stratigraphy. 
Data 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-10 November 2004 
Table 4.1-1. Inputs for Included FEPs (Continued) 
Reference 
Database 
Number Input Source Direct Use In Description 
Input 
Category 
Sections 
6.5.2.3, 6.5.2.5, 
and 6.5.2.7 
Sections 
6.2.15 and 
6.2.20 
Parameters that account for uncertainty in 
permeability (1) effective porosity in the alluvium 
units 7 and 19 (NVF7 and NVF19), (2) FISVO, (3) 
FPVO in the volcanics, (4) alluvium bulk density (bulk 
density). - Direct input for TSPA-Disposition for SZ 
rock properties and water-conducting features in the 
SZ. 
Data 
Sections 6.5 
and 6.5.1 
Section 6.2.19 The effects of future climatic conditions on SZ flow 
are modeled using a convolution integral method and 
scaling breakthrough curves. Direct input for TSPA 
Disposition for Saturated GW flow in the Geosphere. 
Data 
Sections 
6.5.2.8, 
6.5.2.11, and 
6.5.2.12 
Sections 
6.2.25 and 
6.2.30 
Variability in SZ water chemistry is partially 
accounted for through 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; 
colloid retardation factor in the alluvium (CORAL), 
and the colloid retardation factor in volcanic units 
(CORVO). In TSPA Dispositions for chemistry of SZ 
groundwater and sorption in the SZ. 
Data 
DIRS 
170042 
(Continued) 
BSC 2004. Saturated Zone Flow and Transport 
Model Abstraction. MDL-NBS-HS-000021, Rev. 
02. Las Vegas, Nevada: Bechtel SAIC 
Company (Continued). 
Section 6.5.2.6 
Table 6-8 
Section 6.2.29 Matrix diffusion is modeled in the volcanic units 
through the DCVO stochastically sampled parameter. 
Data 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-11 November 2004 
Table 4.1-1. Inputs for Included FEPs (Continued) 
Reference 
Database 
Number Input Source Direct Use In Description 
Input 
Category 
Sections 
6.5.2.11 and 
6.5.2.12 
Section 6.2.31 
Table 6.2-2. 
(1) Radionuclides are transported via colloids 
reversibly sorbed and irreversibly sorbed. (2) 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. 
Data DIRS 
170042 
(Continued) 
BSC 2004. Saturated Zone Flow and Transport 
Model Abstraction. MDL-NBS-HS-000021, Rev. 
02. Las Vegas, Nevada: Bechtel SAIC 
Company (Continued). 
Sections 6.3.1, 
6.3.2, and 
6.5.1.2 
Section 6.2.44 Radionuclide ingrowth is accounted for in two 
different ways; the radionuclide mass entering the SZ 
at the water table is adjusted to account for the 
potential ingrowth of some radioactive decay product; 
a separate set of SZ transport simulations is run to 
calculate explicitly the decay and ingrowth for the 
four main radionuclide chains. Direct input for TSPA 
disposition for RN decay and ingrowth. 
Data 
3-D=three-dimensional; BTC=break through curve ; DIRS=Document Input Reference System; FEP=feature, event, and process; LA=license application; 
RMEI=reasonably maximally exposed individual; RN=radionuclide; SZ=saturated zone; TBD=to be determined; TSPA=total system performance assessment; 
UZ=unsaturated zone. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-12 November 2004 
Table 4.1-2. Input for Excluded SZ FEPs 
DIRS Input Source Direct Use In Description 
Input 
Category 
DIRS 100088 Szabo, B.J. et al. 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. 
Entire 
Document 
Figure 6 
Section 6.2.9 (1) Past climate fluctuations are cyclical and are 
propagated through unsaturated zone to 
saturated zone. (2) Calcite crystal formation a 
function of 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 indicate 
water table dropped by at least 6 m between 
53,000 and 92,000 years ago. (5) Current 
climate represents an extremely arid condition. 
Data 
Justification  Analysis of global climate cycles and their impact onbasin and range mineral deposits in the Basin and Range Province. Peer reviewed journal 
DIRS 100569 Domenico, P.A. and Schwartz, F.W. 1990. 
Physical and Chemical Hydrogeology. New 
York, New York: John Wiley & Sons. 
TIC: 234782. 
Chapter 14 
Equation 
14.11 
Section 6.2.4 Equation for radioactive decay. Established 
Fact 
Justification  Widely used textbook for geochemistry and hydrology written by experts in their field. 
DIRS 101173 Freeze, R.A. and Cherry, J.A. 1979. 
Groundwater. Englewood Cliffs, New Jersey: 
Prentice-Hall. TIC: 217571. 
pp. 106, 404 Sections 
6.2.6 and 
6.2.4 
(1) Carbonate and halite solubilities, volcanic 
rocks tend to weather to clay minerals with a 
relatively small amount of silica going into 
solution; (2) equation for retardation factor. 
Established 
Fact 
Justification  Widely used textbook for geochemistry and hydrology written by experts in their field. 
Figure 8-2 Section 
6.2.16 
Probability and degree of displacement for the 
Bow Ridge Fault. 
Data 
Figure 8-3 Sections 
6.2.7, 6.2.16, 
6.2.17, and 
6.2.18 
Probability and degree of displacement for the 
Solitario Canyon Fault. 
Data 
Section 8.2 Sections 
6.2.7, 6.2.16, 
6.2.17, and 
6.2.18 
A projected 24 m mean fault displacement for 
majority of faults in Yucca Mountain Project 
(YMP) vicinity at a 1x10-8 annual exceedance 
probability. 
Data 
DIRS 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. 
Section 8 Sections 
6.2.7, 6.2.16, 
and 6.2.18 
Mean displacement in host rock is less than 0.1 
cm for a 1x10-8 annual exceedance probability 
between Solitario Canyon and the Ghost Dance 
Faults and within the repository's elevation. 
Data 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-13 November 2004 
Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
DIRS Input Source Direct Use In Description 
Input 
Category 
DIRS 103731 
(Continued) 
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. 
(Continued) 
Figure 4-9 Section 
6.2.16 
Nine regional and fault hazard displacement 
zones within the YM region. 
Data 
Justification Documentation of expert elicitation of fault displacement and seismic activity within the Yucca Mountain vicinity. 
DIRS 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. 
Chapters 2 
and 5 
Sections 
6.2.7, 
6.2.16, 
6.2.17, 
6.2.18 
(1) Within the Basin and Range Province (which 
includes the Yucca Mountain region) peak 
extension stresses occurred between 10 and 12 
Ma with extension rates between 10 to 30 
mm/year. (2) These rapid extension rates 
formed two mayor north trending extension belts 
and normal faulting zones. (3) Approximately 5 
m.y.a regional extensional stress declined to 5 
10 mm/year and are in a declining state today. 
(1) Predicted rise in water table (wt) given future 
seismic events (2) Numerical results using a 
seismic dislocation model indicate the maximum 
rise in the wt would be approximately 10 m. (3) 
Results from the regional stress model approach 
indicated a maximum wt 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 1015 million 
years. 
Established 
Fact 
Justification An analysis to the effects a seismic event would have on water table performed by experts in the field. 
DIRS 107684 Eckerman, K.F. and Ryman, J.C. 1993. 
External Exposure to Radionuclides in Air, 
Water, and Soil, Exposure-to-Dose Coefficients 
for General Application, Based on the 1987 
Federal Radiation Protection Guidance. EPA 
402-R-93-081. Federal Guidance Report No. 
12. Washington, D.C.: U.S. Environmental 
Protection Agency, Office of Radiation and 
Indoor Air. TIC: 225472. 
Table A-1 Section 6.2.4, 
Table 6.2-1 
Radionuclide half-lives. Established 
Fact 
Justification  Radionuclide half-lives needed for the analysis. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-14 November 2004 
Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
DIRS Input Source Direct Use In Description 
Input 
Category 
DIRS 109148 Paces, J.B.; Whelan, J.F.; Forester, R.M.; 
Bradbury, J.P.; Marshall, B.D.; and Mahan, S.A. 
1997. Summary of Discharge Deposits in the 
Amargosa Valley. Milestone SPC333M4. 
Denver, Colorado: U.S. Geological Survey. 
ACC: MOL.19981104.0151. 
Entire Section 
6.2.32 
Analyzes age, isotope, and paleontological data 
and summarizes the current understanding and 
implications of paleo-spring deposits. 
Data 
Justification Isotopic, mineralological, and paleontological study fo water levels over several millennia within the Yucca Mountain region. 
DIRS 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. 
p. 715 Section 
6.2.13 
Viscosity of water value. Established 
Fact 
Justification Widely cited handbook quoted giving properties of liquids under various conditions. 
DIRS 145287 Streeter, V.L. and Wylie, E.B. 1979. Fluid 
Mechanics, 7th Edition. New York, New York: 
McGraw-Hill. TIC: 4819. 
p. 534 Section 
6.2.13 
Density of water value. Established 
Fact 
Justification Widely cited textbook giving properties of liquid and solids. 
DIRS 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. 
Table 
S01053 003 
Sections 
6.2.33 and 
6.2.41 
Little to no organic carbon in these well waters. Data 
Justification Water chemistry analysis used to determine geochemical evolution and current geochemistry of in situ groundwater within the Yucca Mountain 
vicinity. 
DIRS 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. 
Depth to 
water for well 
ID NCEWDP 
19P 
Section 6.2.4 Approximate UZ thickness in region near 
hypothetical pumping well. 
Data 
Justification Water level measurement taken from Nye County wells specifically drilled to assess depth to water, pump-test, geology, and groundwater 
conditions within the Yucca Mountain vicinity. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-15 November 2004 
Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
DIRS Input Source Direct Use In Description 
Input 
Category 
DIRS 164615 
DTN: MO0307MWDNPBDC.001 Nominal 
Performance Biosphere Dose Conversion 
Factors. Submittal date: 07/08/2003. 
BDCF 
Results for 
GW 
Scenario.xls 
Section 6.2.4 
Tables 6.2-1 
and 4.1-2 
BDCFs for selected radionuclides. Data 
Justification Biosphere dose conversion factors developed by experts in the field and used in the TSPA-LA for the Yucca Mountain Project. 
DIRS 167515 DTN:SN0402T0503303.004. Number of Waste 
Packages Hit by Igneous Intrusion. Submittal 
date: 02/13/2004. 
'ConduitCDF' 
subsection of 
spreadsheet 
Section 6.2.4 
Number of waste packages brought to the 
surface by a single volcanic eruption intersecting 
one drift. 
Data 
Justification  Analysis of number of waste packages brought to surface given repository configuration and predictions of dike widths. 
DIRS 169425 BSC 2004. Dissolved Concentration Limits of 
Radioactive Elements. ANL-WIS-MD-000010, 
Rev. 03. Las Vegas, Nevada: Bechtel SAIC 
Company. 
Section 6 Section 
6.2.28 
General statement that the SZ uses radionuclide 
concentration released from the WF solubility 
model report. 
Data 
Justification Analysis of solubility of radionuclides deemed important for Yucca Mountains TSPA-LA by subject matter experts. 
DIRS 169734 BSC 2004. Yucca Mountain Site Description. 
TDR-CRW-GS-000001 REV 02 ICN 01. Two 
volumes. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: DOC.20040504.0008. 
Figure 7-4 Section 
6.2.32 
Discharge Springs south of the Yucca Mountain. Data 
Justification Compendium of geologic and hydrologic information, reports, and data specific to the Yucca Mountain region. 
Section 6.5 Sections 
6.2.34, 
6.2.36, 
6.2.37, 
6.2.38, 
6.2.39, 
6.2.40 
Description of model used to evaluate mountainscale 
effects of thermal loading on host rock due 
to waste emplacement. 
Data DIRS 169866 
BSC 2004. Mountain-Scale Coupled Processes 
(TH/THC/THM) Models. MDL-NBS-HS-000007 
REV 02. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: DOC.20041108.0001. 
Section 
6.5.10 
Sections 
6.2.34, 
6.2.39, 
6.2.40 
Thermal loading on host rock due to waste 
emplacement causes host rock to reach a peak 
temperature of 103C around 1,000 years after 
waste emplacement. 
Data 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-16 November 2004 
Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
DIRS Input Source Direct Use In Description 
Input 
Category 
Section 6.3.1 
Figures 
6.3.1-6 and 
6.3.1-7 
Sections 
6.2.34, 
6.2.39, 
6.2.40 
(1) The thermal pulse due to waste 
emplacement causes water table temperatures 
to peak around 2,000 years after closure. (2) 
Temperatures at the water table below the 
repository footprint locally vary between 32C to 
34C. (3) Beneath the repository, temperatures 
at the water table decrease to within 1C to 2C 
of ambient levels at about 5,000 years after 
waste emplacement. 
Data 
Figure 
6.5.12-2 
Section 
6.2.36 
At 10,000 years, thermal-mechanical stresses 
do not impart significant changes on vertical 
fracture permeabilities beyond 50 m below the 
repository. 
Data 
Sections 
6.5.10, 
6.5.11 
Sections 
6.2.36, 
6.2.37 
(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. 
Data 
Figures 
6.5.12-1, 
6.5.12-2, 
6.5.12-3 
Sections 
6.2.36, 
6.2.38 
Model results: (1) Thermally induced mechanical 
stresses primarily affect vertical fractures 
residing between 150m 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 thermalmechanical 
stresses, but to a significantly lesser 
extent. (3) There are few to no changes in the 
permeabilities of both vertical and horizontal 
fractures located approximately 150m below the 
repository. 
Data 
DIRS 169866 
(Continued) 
BSC 2004. Mountain-Scale Coupled Processes 
(TH/THC/THM) Models. MDL-NBS-HS-000007 
REV 02. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: DOC.20041108.0001. 
(Continued) 
Sections 
6.5.10, 
6.5.11 
Sections 
6.2.36, 
6.2.37 
Above the repository, thermally induced 
stresses are a combination of compressive and 
tensile stresses 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. 
Data 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-17 November 2004 
Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
DIRS Input Source Direct Use In Description 
Input 
Category 
Section 
6.5.11 
Sections 
6.2.36, 
6.2.37, 
6.2.38 
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. 
Data 
Section 
6.5.12 
Sections 
6.2.36, 
6.2.38 
A reduction in vertically aligned fracture 
apertures reduces fracture permeability. 
Data 
Figures 
6.4-12 and 
6.4-16 
Section 
6.2.39 
Modeling results indicate CO2 concentrations 
just above the water table do not vary 
significantly during the modeled time period. 
Data 
Section 
6.4.3.3 
Figures 
6.4-20 to 
6.4-24 
Section 
6.2.39 
Alteration of silicate bearing-minerals decreases 
with distance from the repository due to the 
repository-induced thermal pulse. 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. 
Data 
DIRS 169866 
(Continued) 
BSC 2004. Mountain-Scale Coupled Processes 
(TH/THC/THM) Models. MDL-NBS-HS-000007 
REV 02. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: DOC.20041108.0001. 
(Continued) 
Sections 
6.4.3.3.1, 
6.4.3.3.2, 
and 6.4.3.3.3 
Figures 
6.4-12, 
6.4-13, 
6.4-16, 
6.4-17, and 
6.4-18 
Sections 
6.2.39, 
6.2.40 
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. 
Data 
Justification  Documents an analysis of impact of thermal pulse due to waste emplacement in repository within the Yucca Mountain vicinity by experts in the field. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-18 November 2004 
Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
DIRS Input Source Direct Use In Description 
Input 
Category 
Section 6.2 Sections 
6.2.3, 
6.2.5 
Igneous activity within the Yucca Mountain 
region is now in a relative quiescent phase. 
Data 
Sections 7.1 
and 7.2 
Section 
6.2.4 
Probability of a dike intersecting the repository 
footprint: 1.7x10-8/year; probability of volcanic 
eruption within the repository footprint, 
conditional on dike intersection: 1.3x10-8/year; 
probability of such an eruptive event within 
10,000 years, when dose rate is potentially 
significant: 1.3x10-4/year. 
Data 
DIRS 169989 BSC 2004. Characterize Framework for Igneous 
Activity at Yucca Mountain, Nevada. ANL-MGRGS-
000001 REV 02. Las Vegas, Nevada: 
Bechtel SAIC Company. ACC: 
DOC.20041015.0002. 
Figure 3 
Sections 6.3.2 
and 6.4.2 
Section 
6.2.5 
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. 
Data 
Justification  Documents an analysis and frequency of igneous activity within the Yucca Mountain vicinity by experts in the field. 
DIRS 170001 BSC 2004. Number of Waste Packages Hit by 
Igneous Intrusion. ANL-MGR-GS-000003 REV 
01, Las Vegas, Nevada: Bechtel SAIC Company. 
Section 7.2 Section 
6.2.4 
Number of waste packages brought to the 
surface by a single volcanic eruption intersecting 
one drift. 
Data 
Justification  Documents an analysis of number of waste packages given predicted dike widths and frequency within the Yucca Mountain vicinity. 
DIRS 170002 BSC 2004. Future Climate Analysis. ANL-NBSGS-
000008 REV 01. Las Vegas, Nevada: 
Bechtel SAIC Company. 
ACC: DOC.20040908.0005. 
Section 7 Section 6.2.9 Prediction of a cooler and wetter glacial 
transition climatic condition will follow the brief 
monsoonal period and will persist for about 
8,0008,700 years, 
Data 
Justification  Documents evidence of past global and regional climatic patterns and cycles and predicts future climatic conditions within the Yucca Mountain 
region by experts in the field. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-19 November 2004 
Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
DIRS Input Source Direct Use In Description 
Input 
Category 
DIRS 170006 BSC 2004. Saturated Zone Colloid Transport. 
ANL-NBS-HS-000031 REV 02. Las Vegas, 
Nevada: Bechtel SAIC Company. ACC: 
DOC.20041008.0007. 
Sections 6.4.2 
and 6.5 
Section 
6.2.13 
Colloid filtering and settling observed in lab and 
field tests. 
Data 
Justification  Documents an analysis of colloid characteristics and behavior in Yucca Mountain waters and porous media by experts in the field. 
DIRS 170008 BSC (Bechtel SAIC Company) 2004. 
Hydrogeologic Framework Model for the 
Saturated-Zone Site-Scale Flow and Transport 
Model. MDL-NBS-HS-000024 REV 00. Las 
Vegas, Nevada. Bechtel SAIC Company. 
Figures 6-1 
and 6-18 
Section 6.2.6 Along the predicted SZ transport path the depth 
of carbonate aquifer is over 1,000 m below the 
current water table. 
Data 
Justification  Documents analysis of geologic properties and stratigraphy taken from boreholes and wells located in the Yucca mountain vicinity. 
DIRS 170009 BSC 2004. Water-Level Data Analysis for the 
Saturated Zone Site-Scale Flow and Transport 
Model. ANL-NBS-HS-000034 REV 02. Las 
Vegas, Nevada: Bechtel SAIC Company. ACC: 
DOC.20041012.0002. 
Table 6-3 Section 
6.2.13 
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. 
Data 
Justification Documentation of water-level measurements and hydraulic gradients in the SZ. 
Section 
6.9.11 
Section 
6.2.37 
Effects of thermal loading on faults are excluded 
in the nearfield. 
Data 
Section 6.8.9 Section 
6.2.34 
Thermal effects have an insignificant impact on 
flow in the UZ. 
Data 
Sections 
6.8.12 and 
6.8.14 
Sections 
6.2.36, 
6.2.38, and 
6.2.39 
Repository induced thermo-mechanical stresses 
on fractures, rock properties, and repository 
induced thermal-chemical effects on dissolution 
and precipitation are excluded in the UZ (nearfield). 
Data 
DIRS 170012 BSC 2004. Features, Events, and Processes in 
UZ Flow and Transport. ANL-NBS-MD-000001 
REV 03. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: DOC.20041108.0004. 
Section 6.3.4 Section 
6.2.13 
Radionuclide bearing particles larger than 
colloids are not introduced from the UZ to the 
SZ. 
Data 
Justification  Documents an analysis of UZ flow and transport FEPS in the Yucca Mountain vicinity. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-20 November 2004 
Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
DIRS Input Source Direct Use In Description 
Input 
Category 
DIRS 170015 BSC 2004. Recharge and Lateral Groundwater 
Flow Boundary Conditions for the Saturated Zone 
Site-Scale Flow and Transport Model. ANL-NBSMD-
000010 REV 01. Las Vegas, Nevada: Bechtel 
SAIC Company. ACC: DOC.20041008.0004. 
Table 6-2 Section 6.2.4 Estimated recharge flux rates in upper Jackass 
Flats is 2.21 mm/year. 
Data 
Justification Documentation of an analysis that interpolates flow from a large scale regional flow system within the Yucca Mountain area, to that through 
boundaries of a smaller region embedded within the larger region. 
Section 
6.2.1.1 
Section 6.2.7 Tectonic activity in the Yucca Mountain region is 
in a waning phase with the focal point moving 
westward. 
Data 
Section 
6.2.1.10 
Sections 
6.2.16, 
6.2.17, 
6.2.18, 
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. 
Data 
Section 
6.2.1.10 
Sections 
6.2.16, 
Zone of alteration in rock can extend a few 
meters to tens of meters due to fault 
displacement. 
Data 
Section 
6.2.1.10 
Sections 
6.2.17, 
6.2.18, 
Energy produced from a seismic event will be 
dissipated along existing faults. 
Data 
DIRS 170017 BSC 2004. Features, Events, and Processes: 
Disruptive Events. ANL-WIS-MD-000005 REV 02. 
Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20041108.0002. 
Section 
6.2.1.10 
Sections 
6.2.17 
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 
Data 
Justification  Documents an analysis of disruptive events and how they may effect the geology and geologic properties within the vicinity of Yucca Mountain. 
DIRS 170022 BSC 2004. Initial Radionuclide Inventories. ANLWIS-
MD-000020 REV 01. Las Vegas, Nevada: 
Bechtel SAIC Company. ACC: 
DOC.20040921.0003, Nevada: Bechtel SAIC 
Company. 
Table 7-1, 
Appendix III 
Section 6.2.4 Grams and activity of radionuclides per CSNF 
waste package - nominal case. 
Data 
Justification  Documents an analysis of number of waste packages, including their content and activity, that are expected to be disposed at Yucca Mountain. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-21 November 2004 
Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
DIRS Input Source Direct Use In Description 
Input 
Category 
DIRS 170025 BSC 2004. Waste Form and In-Drift Colloids- 
Associated Radionuclide Concentrations: 
Abstraction and Summary. MDL-EBS-PA-000004 
REV 01. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: DOC.20041028.0007. 
Section 1.2 
and 
Appendix I, 
Section I-3 
Section 
6.2.13 
(1) Upper limit of colloid diameter. 
(2) Colloid-particle density (Dp) values. 
Data 
Justification  Documents an analysis of colloids and their characteristics produced from Yucca Mountain waste. 
Appendix A, 
Section A4 
Section 
6.2.33 
The range of groundwater compositions in the 
SZ are represented by water taken from wells 
UE-25p#1 and J-13 and used to derive Kd 
distributions. 
Data 
Table 
6.6-1b 
Section 
6.2.39 
In the model, no credit is being taken for 
sorption onto zeolites that reside along the SZ 
flow path. 
Data 
Section 6.3 
Appendix F 
Section 
6.2.26 
Model assumes that the SZ groundwaters along 
the transport path are oxidizing from the UZ/SZ 
interface to the 18-km compliance boundary. 
Data 
DIRS 170036 BSC 2004. Site-Scale Saturated Zone Transport. 
MDL-NBS-HS-000010 REV 02. Las Vegas, 
Nevada: Bechtel SAIC Company. ACC: 
DOC.20041103.0004. 
Appendix E Section 
6.2.32 
Modeling a higher water table beneath the 
repository manifests a water table rise to within 
5 m of the surfaces corresponding to the three 
paleo-spring deposits located along Highway 95 
and at the southern end of Crater Flat. 
Data 
Justification  Documents an analysis of SZ transport processes for radionuclides through the hydrogeology system in the Yucca Mountain area given likely 
scenarios and climatic futures. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-22 November 2004 
Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
DIRS Input Source Direct Use In Description 
Input 
Category 
Figure A6-3 Section 6.2.5 Evidence of past hydrothermal mineral alteration 
seen in Calico Hills, Claim Canyon, and along 
the south flank of Shoshone Mountain, which lie 
north and northeast of Yucca Mountain, is not 
along the SZ flow path. 
Data 
Figure 6-4 Section 
6.2.32 
The Solitario Canyon Splay fault serves as a 
groundwater divide. 
Data 
Section 
A -6.3 
Sections 
6.2.26, 
6.2.33 
Paleoclimate recharge waters are reflective of 
cooler climatic conditions and cooler recharge 
waters 10,00016,000 years old. 
Data 
Section 
A -7.1 
Section 6.2.9 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. 
Data 
Section 
A -7.1.2 
Sections 
6.2.7, 
6.2.26, 
6.2.33 
Geochemical analysis indicates the current SZ 
groundwater under the repository and along the 
SZ transport path is paleoclimate recharge 
water. 
Data 
Section 
A -7.1.4 
Section 
6.2.7 
Geochemical modeled flow patterns and 
deduced mixing zones of paleoclimate waters 
derived from hydrochemical and isotopic data. 
Data 
Section 
7.2.4.1.1 
Section 
6.2.13 
The temperature range for Yucca Mountain SZ 
waters is approximately 20C to 55C, with the 
majority of temperatures within the upper 20C 
to lower 30C. 
Data 
Figure 
7-4 
Section 
6.2.13 
Permeability of the confining unit between the 
carbonate aquifer and the Bullfrog unit is 10-15 
m2. 
Data 
DIRS 170037 BSC (Bechtel SAIC Company) 2004. Saturated 
Zone Site-Scale Flow Model. MDL-NBS-HS- 
000011, Rev. 02. Las Vegas, Nevada: Bechtel 
SAIC Company. 
Figure 
7-4 
Section 
6.2.13 
Mean permeability value for the alluvium is 2.0 x 
10-13 m2. 
Data 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-23 November 2004 
Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
DIRS Input Source Direct Use In Description 
Input 
Category 
Section 
6.6.1.4 
Section 
6.2.13 
On a regional scale, fracture permeability in the 
Bullfrog, Tram, and Prow Pass units ranges over 
3 orders of magnitude. 
Data 
Section 
6.4.3.2 
Figure 6-7 
Section 
6.2.16 
The Imbricate Fault Zone has relatively lower 
anisotropy ratios than other volcanic zones in 
the SZ flow domain. 
Data 
Section 
6.5.3.4 
Section 
6.2.16 
(1) The Bow Ridge Fault is one of many faults 
incorporated in the Imbricate Fault Zone. (2) 
Hydrological properties and dimensions of the 
Imbricate Fault Zone. 
Data 
Section 6.3.2 Section 
6.2.17 
Solitario Canyon Fault is a groundwater divide 
between the Yucca Mountain and the Crater Flat 
regions. 
Data 
Figures 6-4 
and 6-6 
Sections 
6.2.20, 
6.2.32 
Figure 6.2-3 
(1) Geologic features in the area of the model. 
(2) The Solitario Canyon Splay fault serves as a 
groundwater divide. 
Data 
Section 2.4.4 Section 
6.2.26 
On a regional scale, fracture permeability in the 
Bullfrog, Tram and Prow Pass units ranges over 
3 orders of magnitude. 
Data 
Section 
A6.6.6.6.2 
Sections 
6.2.26 and 
6.2.33 
Paleoclimate recharge waters are reflective of 
cooler climatic conditions and cooler recharge 
waters 10,00016,000 years old. 
Data 
Figure 6-11 Section 
6.2.32 
Modeling a higher water table beneath the 
repository manifests a water table rise to within 
5 m of the surface corresponding to the three 
paleo-spring deposits located along Highway 95 
and at the southern end of Crater Flat. 
Data 
Table 7-9 Sections 
6.2.34, 
6.2.40 
Temperatures in UE-25-p#1 increase with depth 
with some as high as 40C to 45C. 
Data 
DIRS 170037 
(Continued) 
BSC 2004. Saturated Zone Site-Scale Flow 
Model. MDL-NBS-HS-000011, Rev. 02. Las 
Vegas, Nevada: Bechtel SAIC Company. 
(Continued) 
Section 
A6.7.1.2 
Section 
6.2.45 
Examples of naturally occurring isotopes within 
the SZ flow domain (84Sr, 86Sr, 87Sr, 88Sr, 234U, 
238U, 12C, 13C). 
Data 
Justification  Documents numerical analysis of potential flow paths between Yucca Mountain and the 18-km boundary. Inputs for the geologic properties and 
predicted water levels are assessed by subject matter experts. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-24 November 2004 
Table 4.1-2. Input for Excluded SZ FEPs (Continued) 
DIRS Input Source Direct Use In Description 
Input 
Category 
DIRS 170760 DTN: MO0407SEPFEPLA.000. LA FEP List. 
Submittal date: 07/31/2003. 
SZ FEPs Sections 
1.2.1, 1.2.2, 
and 6.1 
Tables 1.2-1, 
4.1-1, and 
4.1-2 
List of TSPA-LA FEPs. Data 
Justification List of site-specific Features, Events, and Processes deemed important in determining and developing conceptual and numerical models specific to 
Yucca Mountain. 
DIRS 170768 DTN: LA0407DK831811.001. Physical 
Parameters of Basaltic Magma and Eruption 
Phenomena. Submittal date: 07/15/2004. 
Entry for dike 
widths 
(thickness) 
Section 6.2.3 Dimension of basaltic dikes in the YM vicinity. Data 
Justification Dimension of mean value for dike widths that may intrude in SZ site-scale model for Yucca Mountain vicinity, which is appropriate for this screening 
argument. 
BDCF=biosphere dose conversion factor; DIRS=Document Input Reference System; FEP=feature, event, and process; LA=license application; RN=radionuclide; 
SZ=saturated zone; TSPA=total system performance assessment; UZ=unsaturated zone; YM=Yucca Mountain 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-25 November 200 
Table 4.1-3. Direct Input from Regulation 10 CFR Part 63 Used for the SZ FEP Screening 
Regulatory Section 
10 CFR 63 (DIRS 156605) 
Section in 
the Report Input Description 
63.2 6.2.43 Definition of the reference biosphere in which the RMEI will reside. 
63.2, 
63.305 (a), (b), (c), (d) 
5.3, 
6.2.11, 
6.2.26, 
6.2.32, 
6.2.46 
(1) 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 and can be used to 
predict 10,000 years into the future in TSPA; (2) present socio-economic practices are reflective of future practices 
(prohits changes in society or reference biosphere); (3) Guidance for identifying and examining the effects of FEPs in a 
performance assessment on the Yucca Mountain disposal system. 
63.102 (j) 6.2.46 The disposal system includes the saturated zone whicn is part of the natural barrier system. 
63.102 (j), 
63.114 (d), (e), (f), 
63.342 
4.2.3, 
6.1.2 
6.2.46 
(1) Concept of performance assessment and inclusion or exclusion of FEP. (2) FEP exclusion due to low consequence 
criteria. (3) FEP exclusion due to low probability criterion. 
63.312 (a), (b), (c), (d), (e) 
6.2.12, 
6.2.21, 
6.2.23, 
6.2.32, 
6.2.43 
(1) Characteristics of the RMEI to be used in exposure calculations. (2) Distance from the repository to the receptor 
location. (3) Volume of water within the reference biosphere used to determine RN concentration (3,000 acre-ft). 
63.321 6.2.46 The regulation specifies only a single stylized instance of human interference will ocurr in the engineered and natural 
barrier system and no others. 
63.332 (a)(3) 6.2.4, 
6.2.12,6.2. 
21, 6.2.23, 
6.2.32 
Representative volume of groundwater used to determine RN concentration (3,000 acre-ft). 
FEP=feature, event, and process; RMEI=reasonably maximally exposed individual; RN=radionuclide; TSPA=total system performance assessment 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-26 November 2004 
4.2 CRITERIA 
This section addresses the criteria relevant to the FEP screening process. The criteria relevant to 
the FEP screening process stem from the applicable regulations at 10 CFR Part 63 
(DIRS 156605), as identified in the Project Requirements Document (PRD) (Canori and Leitner 
2003 [DIRS 166275]). These criteria find expression as specific acceptance criteria presented by 
the NRC in Yucca Mountain Review Plan, Final Report (YMRP) (NRC 2003 [DIRS 163274], 
Sections 2.2.1.2.1.3 and 2.2.1.2.2.3). The correlation between the regulations and YMRP 
acceptance criteria is shown in Table 4.2-1. Satisfaction of the criteria is discussed in 
Section 7.1. 
4.2.1 Project Requirements Document 
The PRD (Canori and Leitner 2003 [DIRS 166275]) documents and categorizes the regulatory 
and other Project requirements and provides a crosswalk to the YMP organizations responsible 
for ensuring that the criteria are addressed in the LA. The regulatory requirements include 
criteria relevant to performance assessment activities, in general, and to FEP-related activities as 
they pertain to performance assessment, in particular. Table 4.2-1 provides a crosswalk between 
the regulatory requirements and the PRD locator for these requirements. 
4.2.2 Yucca Mountain Review Plan 
The NRC will be reviewing the LA. The basis of the review is described in the YMRP 
(NRC 2003 [DIRS 163274], Sections 2.2.1.2), and the bases for acceptance are stated as 
acceptance criteria. In Table 4.2-1, YMRP acceptance criteria are correlated to the 
corresponding regulations as they pertain to FEP-related criteria. 
The cited YMRP (NRC 2003 [DIRS 163274]) criteria are provided in Table 4.2-2. The YMRP 
acceptance criteria for FEP screening echo the regulatory screening criteria of low probability 
and low consequence but also allow for exclusion of a FEP if the process is specifically excluded 
by the regulations (see Section 4.2.3). 
Table 4.2-1. Relationships of Regulations to the YMRP Acceptance Criteria 
Regulatory 
Citation 
Associated 
PRD Description of the Applicable 
Regulatory Requirement or 
Acceptance Criterion 
10 CFR Part 63 
(DIRS 156605) 
Canori and Leitner 2003 
(DIRS 166275) 
Associated Criteria 
in the YMRP 
(DIRS 163274) 
General Requirements and Scope Pertinent to FEP Screening 
Include data related to geology, 
hydrology, geochemistry, and 
geophysics 
Include information of the design 
of the engineered barrier system 
used to define parameters and 
conceptual models 
63.114(a) 
PRD-002/ 
T-015 
2.2.1.2.1.3 
Acceptance Criterion 1 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-27 November 2004 
Table 4.2-1. Relationships of Regulations to the YMRP Acceptance Criteria (Continued) 
Regulatory 
Citation 
Associated 
PRD Description of the Applicable 
Regulatory Requirement or 
Acceptance Criterion 
10 CFR Part 63 
(DIRS 156605) 
Canori and Leitner 2003 
(DIRS 166275) 
Associated Criteria 
in the YMRP 
(DIRS 163274) 
Account for uncertainties and 
variabilities in parameter values 
and provide the technical basis for 
parameter ranges, probability 
distributions, or bounding values 
63.114(b) PRD-002/ 
T-015 
2.2.1.2.2.3 
Acceptance Criteria 
2 and 5 
FEP Screening Criteria 
Provide the justification and 
technical basis for excluding FEPs 
specifically excluded by regulation. 
63.114(e) PRD-002/ 
T-015 
2.2.1.2.1.3 
Acceptance Criterion 2 
Provide the technical basis for 
either inclusion or exclusion of 
FEPs. Provide the justification and 
technical basis for those excluded 
based on probability. 
63.114(f) PRD-002/ 
T-015 
2.2.1.2.1.3 
Acceptance Criterion 2 
Provide the technical basis for 
either inclusion or exclusion of 
FEPs. Provide the justification and 
the technical basis for those 
excluded based on lack of 
significant change in resulting 
radiological exposure or release to 
the accessible environment. 
63.114 (e), (f) 
PRD-002/ 
T-015 
2.2.1.2.1.3 Acceptance 
Criterion 2 
FEP=feature, event, and process; PRD=Project Requirements Document 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-28 November 2004 
Table 4.2-2. Relevant YMRP Acceptance Criteria 
YMRP Section Acceptance Criterion Description 
1. The Identification of a 
list of FEPs Is 
Adequate 
(1) The Safety Analysis Report contains a complete list of FEPs 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. 
Scenario Analysis 
and Event 
Probability: 
Scenario Analysis 
(from 
Section 2.2.1.2.1.3 
NUREG-1804 
[DIRS 163274]) 2. Screening of the Initial 
List of Features, 
Events, and 
Processes Is 
Appropriate 
(1) The DOE has identified all FEPs 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. 
(2) The DOE has provided justification for those FEPs that have been excluded. An acceptable 
justification for excluding FEPs is that either the FEP is specifically excluded by regulation; probability of 
the FEP (generally an event) falls below the regulatory criterion; or omission of the FEP 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. 
(3) The DOE has provided an adequate technical basis for each FEP excluded from the performance 
assessment to support the conclusion that either the FEP is specifically excluded by regulation, the 
probability of the FEP falls below the regulatory criterion, or omission of the FEP 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. 
Scenario Analysis 
and Event 
Probability: 
Identification of 
Events with 
Probability Greater 
than 10-8 per Year 
(from 
Section 2.2.1.2.2.3 
NUREG-1804 
[DIRS 163274]) 
1. Events are Adequately 
Defined 
(1) Events or event classes are defined without ambiguity and used consistently in probability models, 
such that probabilities for each event or event class are estimated separately. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-29 November 2004 
Table 4.2-2. Relevant YMRP Acceptance Criteria (Continued) 
YMRP Section Acceptance Criterion Description 
Scenario Analysis 
and Event 
Probability: 
(Continued) 
(Continued) (2) Probabilities of intrusive and extrusive igneous events are calculated separately. Definitions of faulting 
and earthquakes are derived from the historical record, paleoseismic studies, or geological analyses. 
Criticality events are calculated separately by location. 
2. Probability Estimates 
for Future Events Are 
Supported by 
Appropriate Technical 
Bases. 
(1) Probabilities for future natural events have considered past patterns of the natural events in the 
Yucca Mountain region, considering the likely future conditions and interactions of the natural and 
engineered repository system. These probability estimates have specifically included igneous events, 
faulting and seismic events, and criticality events. 
5. Uncertainty in Event 
Probability is 
Adequately Evaluated 
(1) Probability values appropriately reflect uncertainties. Specifically: 
a. The DOE provides a technical basis for probability values used, and the values account for the 
uncertainty in the probability estimates. 
b. The uncertainty for reported probability values adequately reflects the influence of parameter 
uncertainty on the range of model results (i.e., precision) and the model uncertainty, as it affects 
the timing and magnitude of past events (i.e., accuracy). 
DOE=U.S. Department of Energy; FEP=feature, event, and process. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-30 November 2004 
4.2.3 FEPs Screening Criteria 
The criteria for determining low probability, low consequence, or by regulation exclusions are 
described below. 
4.2.3.1 Low Probability 
The low-probability criterion is stated in 10 CFR 63.114(d) (DIRS 156605): 
Consider only events that have at least one chance in 10,000 of occurring over 
10,000 years. 
and supported by 10 CFR 63.342: 
The Department of Energys (DOE) performance assessments shall 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. 
As noted in Assumption 5.2, the low-probability criterion for very unlikely events corresponds to 
an annual-exceedance probability of 10-8. 
4.2.3.2 Low Consequence 
The low consequence criterion is stated in 10 CFR 63.114 (e), (f) (DIRS 156605): 
(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 
radiation exposure 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. 
and supported by 10 CFR 63.342: 
DOEs performance assessments need not evaluate the impacts resulting from any 
features, events, and processes or sequences of events and processes with a higher 
chance of occurrence if the results of the performance assessments would not be 
changed significantly. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 4-31 November 2004 
Some FEPs have a beneficial effect on the TSPA, as opposed to an adverse effect. As identified 
in 10 CFR 63.102(j) (DIRS 156605), the concept of a performance assessment includes: 
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 YMRP (NRC 2003 [DIRS 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 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 that supports the selection of models and parameter 
ranges or distributions must be provided. 
On the basis of these statements, those FEPs that are demonstrated to have only beneficial effects 
on the radiation exposure to the RMEI, or radionuclide releases to the accessible environment, 
can be excluded on the basis of low consequence because they have no adverse effects on 
performance. 
4.2.3.3 By Regulation 
The YMRP (NRC 2003 [DIRS 163274], Section 2.2.1.2.1.3, Acceptance Criterion 2 allows for 
exclusion of a FEP if the process is specifically excluded by the regulations: 
The DOE has provided justification for those FEPs that have been excluded. An 
acceptable justification for excluding FEPs is that either the FEP is specifically 
excluded by regulation; probability of the FEP (generally an event) falls below the 
regulatory criterion; or omission of the feature, 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. 
4.3 CODES, STANDARDS, AND REGULATIONS 
No codes, standards, or regulations other than those identified in Project Requirements 
Document (Canori and Leitner 2003 [DIRS 166275], Table 2-3) and determined to be applicable 
(Table 4.2-1) were used in this analysis. 

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5. ASSUMPTIONS 
Each assumption made in this analysis contains a description of where it is applied and 
justification for its use. 
5.1 ASH FALL LEACHING AND SZ TRANSPORT 
The following assumption is made to estimate the potential impact of leaching contaminants 
from ash fall on the release to the accessible environment (FEP 1.2.04.07.0B, Ash Redistribution 
in Groundwater, Section 6.2.4 of this document). 
AssumptionA volcanic eruption occurs immediately after waste emplacement. 
JustificationAn assumption that a volcanic eruption occurs immediately after waste 
emplacement maximizes the impact of short-lived radionuclides, contributing to radiation 
exposure to the RMEI, with regard to the timing of the release. 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). 
AssumptionFor postclosure naturally occurring FEPs, the probability criterion also can be 
expressed as an annual exceedance probability (i.e., 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 1 chance in 10,000 in 10,000 years (10-4/104 year) is 
equivalent to a 10-8 annual-exceedance probability or annual-exceedance frequency. A stated 
definition of unlikely events as having 1 chance in 10 in 10,000 years (10-1/104 year) of 
occurring is equivalent to a 10-5 annual-exceedance probability or annual-exceedance frequency. 
JustificationThe definition of annual exceedance probability and the following justification for 
this assumption are taken from Characterize Framework for Seismicity and Structural 
Deformation at Yucca Mountain, Nevada (BSC 2004 [DIRS 168030], Glossary). 
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 probability density function that is often used 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.1 This is inferred to mean that naturally occurring, infrequent, and independent 
1 Merriam-Websters Collegiate Dictionary, 10th ed., s.v. Poisson distribution. 

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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 (BSC 2004 [DIRS 168030], 
Section 6.4.2), 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 
AssumptionPotential naturally occurring events, perhaps of different magnitude, have occurred 
at least once in the past within the geologic record used as the basis for determining factors that 
could affect the Yucca Mountain disposal system over the next 10,000 years. 
JustificationThis assumption is justified because it is consistent with the regulations used as 
direct input. At 10 CFR 63.305(c) (DIRS 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. 
The implication of this assumption is that any discernible impacts or processes related to past 
events at the site setting are 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, then they are either of low consequence or of low probability and 
can be excluded from consideration. Because it is consistent with the regulations, no further 
confirmation is necessary. 
Use: This assumption is germane to FEPs related to processes or phenomena that, speculatively, 
could affect future states of the system, but for which the magnitude of 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. These types of events are known to occur. However, the effects of the phenomenon 
or the effects associated with varying magnitudes of the event type and probabilities are not well 
documented (e.g., effects of a supernova); the form of the coupling process is not well defined 
(e.g., changes in the earth's magnetic field); or the phenomenon has been shown to have no 
impact or insignificant impact at the present time (e.g., earth tides). 

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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). 

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ANL-NBS-MD-000002 REV 03 6-1 November 2004 
6. ANALYSIS 
The following sections discuss the SZ FEP analyses. Section 6.1 of this report discusses the 
methods and approach used for the FEP screening. Sections 6.2.1 to 6.2.46 provide the 
screening documentation. 
6.1 APPROACH 
The identification and screening of a comprehensive list of FEPs potentially relevant to the 
postclosure performance of the Yucca Mountain repository is an ongoing, iterative process based 
on site-specific information, design, and regulations. FEP analysis uses the following 
definitions, as taken from the YMRP (NRC 2003 [DIRS 163274], Glossary): 
feature  An object, structure, or condition that has a potential to affect disposal 
system performance. 
event  A natural or human-caused phenomenon that has a potential to affect 
disposal system performance and occurs during an interval that is short 
compared to the period of performance. 
process  A natural or human-caused phenomenon that has a potential to affect 
disposal system performance and operates during all or a significant part 
of the period of performance. 
FEP analysis for TSPA-LA is described in the Development of the Total System Performance 
Assessment-License Application Features, Events, and Processes (BSC 2004 [DIRS 168706]). It 
is summarized in the following subsections. 
6.1.1 FEP Identification 
The first step of FEP analysis is FEP identification and classification, which addresses 
Acceptance Criterion 1 of the YMRP (NRC 2003 [DIRS 163274], Section 2.2.1.2.1.3). The 
TSPA-LA FEP identification and classification process is described in The Development of the 
Total System Performance Assessment-License Application Features, Events, and Processes 
(BSC 2004 ([DIRS 168706], Section 3). This process produced a version of the LA FEP List 
(DTN: MO0407SEPFEPLA.000 [DIRS 170760]) used as initial input in this SZ FEP analysis. 
Subsequent modifications to the FEP list from the information shown in 
DTN: MO0407SEPFEPLA.000 [DIRS 170760], aside from editorial corrections to FEP 
descriptions, are discussed later in this section. All subsequent modifications are also 
documented in the FEP History File in the FEP database (BSC 2004 [DIRS 168706], 
Table 6-2). 
6.1.2 FEP Screening Process 
The second step of FEP analysis is FEP screening, which addresses Acceptance Criterion 2 of 
the YMRP (NRC 2003 [DIRS 163274], Section 2.2.1.2.1.3). The TSPA-LA FEP screening 
process is described in the Development of the Total System Performance Assessment-License 
Application Features, Events, and Processes (BSC 2004 [DIRS 168706], Section 4). 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-2 November 2004 
For FEP screening, each FEP is screened against the specified exclusion criteria (see 
Section 4.2.3), summarized in the following FEP screening statements: 
 FEPs having less than one chance in 10,000 of occurring over 10,000 years may be 
excluded (screened out) from the TSPA on the basis of low probability (as per 
10 CFR 63.114(d) and 63.342 [DIRS 156605]). 
 FEPs whose omission would not significantly change the magnitude and time of the 
resulting radiological exposures to the RMEI, or radionuclide releases to the accessible 
environment, may be excluded (screened out) from the TSPA on the basis of low 
consequence (as per 10 CFR 63.114 (e), (f) and 63.342 [DIRS 156605]). 
 FEPs that are inconsistent with the characteristics, concepts, and definitions specified in 
10 CFR Part 63 (DIRS 156605) may be excluded (screened out) from the TSPA by 
regulation. 
A FEP need only satisfy one of the exclusion screening criteria to be excluded from TSPA. A 
FEP that does not satisfy any of the exclusion screening criteria must be included (screened in) in 
the TSPA-LA model. 
This report documents the screening decisions for the SZ FEPs. In cases where a FEP covers 
multiple technical areas and is shared with other FEP reports, this report provides only a partial 
technical basis for the screening decision as it relates to SZ issues. The full technical basis for 
these shared FEPs is addressed, collectively, by all of the sharing FEP analysis reports. 
Documentation of the screening for each FEP is provided in Section 6.2 using the following 
standardized format. There may be instances where additional text is presented for either 
included or excluded FEPs. The text provides background information and/or a high level of 
detail supporting either the exclusion argument or the TSPA-LA disposition. 
Section Number (e.g., Section 6.2.x) FEP Name (FEP Number) 
FEP Description: This field describes the nature and scope of the FEP under 
consideration. 
Screening Decision: Identifies the screening decision as one of: 
- Included 
- Excluded  Low Probability 
- Excluded  Low Consequence 
- Excluded  By Regulation 
In a few cases, a FEP may be excluded by a combination of two criteria (e.g., Low 
Probability and Low Consequence). 
Screening Argument: This field is used only for excluded FEPs. It provides the 
discussion for why a FEP has been excluded from TSPA-LA. 

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ANL-NBS-MD-000002 REV 03 6-3 November 2004 
TSPA Disposition: This field is used only for included FEPs. It provides the 
consolidated discussion of how a FEP has been included in TSPA-LA, making reference 
to more detailed documentation in other supporting technical reports, as applicable. 
Supporting Reports: This field is only used for included FEPs. It provides the list of 
supporting technical reports that identified the FEP as an included FEP and contain 
information relevant to the implementation of the FEP within the TSPA-LA model. This 
list of supporting technical reports provides traceability of the FEP through the document 
hierarchy. For excluded FEPs, it is indicated as Not Applicable. 
Supplemental Discussion: This provides additional or detailed information to support 
the screening argument or disposition. 
6.1.3 Supporting Reports and Inputs 
Table 6.1-1 provides a list of SZ model and analysis reports that support the rationale for those 
SZ FEPs included in the TSPA-LA. Some SZ analysis and model reports provide expanded 
discussions of a FEP topic, while other reports discuss a FEP topic in only a cursory fashion. 
The rationale for excluding an SZ FEP is provided in this report. The sources of data and 
technical information used in the screening arguments are cited within each FEP discussion 
provided in this report. The TSPA-LA dispositions of included FEPs are provided in this report 
as well. 
Table 6.1-1. SZ Analysis and Model Reports Used to Support SZ Included FEPs 
TSPA- LA 
FEP Number 
FEP Name Supporting Analysis and Model Reports Used in Developing the TSPA Disposition 
1.2.02.01.0A 
Fractures 
 Hydrogeologic Framework Model for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170008]) 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]) 
1.2.02.02.0A 
Faults 
 Hydrogeologic Framework Model for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170008]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]) 
1.3.07.02.0A 
Water table 
rise affects SZ 
 Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model 
(BSC 2004 [DIRS 170009]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-4 November 2004 
Table 6.1-1. SZ Analysis and Model Reports Used to Support SZ Included FEPs (Continued) 
TSPA- LA 
FEP Number 
FEP Name Supporting Analysis and Model Reports Used in Developing the TSPA Disposition 
1.4.07.01.0A 
Water 
management 
activities 
 Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model 
(BSC 2004 [DIRS 170009]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
1.4.07.02.0A 
Wells 
 Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model 
(BSC 2004 [DIRS 170009]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
2.2.03.01.0A 
Stratigraphy 
 Hydrogeologic Framework Model for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170008]) 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]) 
2.2.03.02.0A 
Rock 
properties of 
host rock and 
other units 
 Hydrogeologic Framework Model for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170008]) 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]) 
2.2.07.12.0A 
Saturated 
groundwater 
flow in the 
geosphere 
 Recharge and Lateral Groundwater Flow Boundary Conditions for the Saturated Zone 
Site-Scale Flow and Transport Model (BSC 2004 [DIRS 170015]) 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]) 
2.2.07.13.0A 
Waterconducting 
features in the 
SZ 
 Hydrogeologic Framework Model for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170008]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]) 

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ANL-NBS-MD-000002 REV 03 6-5 November 2004 
Table 6.1-1. SZ Analysis and Model Reports Used to Support SZ Included FEPs (Continued) 
TSPA- LA 
FEP Number 
FEP Name Supporting Analysis and Model Reports Used in Developing the TSPA Disposition 
2.2.07.15.0A 
Advection and 
dispersion in 
the SZ 
 Recharge and Lateral Groundwater Flow Boundary Conditions for the Saturated Zone 
Site-Scale Flow and Transport Model (BSC 2004 [DIRS 170015]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]) 
2.2.07.16.0A 
Dilution of 
radionuclides 
in groundwater 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
2.2.07.17.0A 
Diffusion in the 
SZ 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Saturated Zone Colloid Transport (BSC 2004 [DIRS 170006]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]) 
2.2.08.01.0A 
Chemical 
characteristics 
of groundwater 
in the SZ 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037])  Appendix A 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
2.2.08.06.0A 
Complexation 
in the SZ 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
2.2.08.08.0A 
Matrix diffusion 
in the SZ 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone Colloid Transport (BSC 2004 [DIRS 170006]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]) 
2.2.08.10.0A 
Colloidal 
transport in the 
SZ 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Colloid Transport (BSC 2004 [DIRS 170006]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]) 
2.2.08.09.0A 
Sorption in the 
SZ 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone Colloid Transport (BSC 2004 [DIRS 170006]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]) 

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Table 6.1-1. SZ Analysis and Model Reports Used to Support SZ Included FEPs (Continued) 
TSPA- LA 
FEP Number 
FEP Name Supporting Analysis and Model Reports Used in Developing the TSPA Disposition 
2.2.10.03.0A 
Natural 
geothermal 
effects on flow 
in the SZ 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
2.2.12.00.0B 
Undetected 
features on the 
SZ 
 Hydrogeologic Framework Model for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170008]) 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]) 
3.1.01.01.0A 
Radioactive 
decay and 
ingrowth 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
FEP=feature, event, and process; LA=license application; SZ=saturated zone; TSPA=total system performance 
assessment. 
6.1.4 Qualification of Unqualified Direct Inputs 
Direct inputs are listed in Table 4.1-1. Unqualified data used elsewhere in the report are 
qualified in Appendix A. 
6.1.5 Assumptions and Simplifications 
For included FEPs, the TSPA dispositions may include statements regarding assumptions made 
to implement the FEP within the TSPA-LA model. Such statements are descriptive of the 
manner in which the FEP has been included and are not used as the basis of the screening 
decision to include the FEP with the TSPA-LA model. Because the individual FEPs are specific 
in nature, any discussion of applicable mathematical formulations, equations, algorithms, 
numerical methods, or idealizations or simplifications is provided within the individual FEP 
discussions in Section 6.2. 
6.1.6 Intended Use and Limitations 
The intended use of this report is to provide FEP screening information for a Project-specific 
FEP database, and to promote traceability and transparency regarding FEP screening. This 
report is intended to be used as the source documentation for the FEP database described in The 
Development of the Total System Performance Assessment-License Application Features, Events, 
and Processes (BSC 2004 [DIRS 168706]). For included FEPs, this document summarizes and 
consolidates the method of implementation of the FEP in TSPA-LA in the form of TSPA 
disposition statements, based on more detailed implementation information in the listed 

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supporting technical reports. For excluded FEPs, this document provides the technical basis for 
exclusion in the form of screening arguments. 
Inherent in this evaluation approach is the limitation that the repository will be constructed, 
operated, and closed according to the design used as the basis for the FEP screening and in 
accordance with NRC license requirements. This is inherent in performance evaluation of any 
engineering project, and design verification and performance confirmation are required as part of 
the construction and operation processes. The results of the FEP screening presented herein are 
specific to the repository design evaluated in this report for TSPA-LA. Any changes in direct 
inputs listed in Section 4.1, in baseline conditions used for this evaluation, or in other subsurface 
conditions, will need to be evaluated to determine if the changes are within the limits stated in 
the FEP evaluations. Engineering and design changes are subject to evaluation to determine if 
there are any adverse manner impacts to safety as codified at 10 CFR 63.73 and in Subparts F 
and G (DIRS 156605). See also the requirements at 10 CFR 63.44 and 10 CFR 63.131. 
6.2 ANALYSIS OF SZ FEPS 
Screening information for each of the 46 SZ FEPs is presented in separate subsections. FEPs are 
addressed in numerical order based on the FEP number. 
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. 
Screening Decision: Included 
Screening Argument: N/A 
TSPA Disposition: 
Groundwater flow through fractures in the volcanic units is included in the SZ flow and transport 
model Saturated Zone Flow and Transport Model Abstraction (BSC 2004 
[DIRS 170042]). Groundwater flow through fractures in the volcanic units is modeled in the 
Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037], Sections 6.3.3, 6.5.1, 8.3.2) 
using an effective continuum approach (BSC 2004 [DIRS 170037], Section 6.5.1) implemented 
in the numerical code FEHM V2.20 STN: 10086-2.20-00 (LANL 2003 [DIRS 161725]). 
Observations at Yucca Mountain indicate that in the fractured volcanic units delineated in the 
hydrogeologic framework model (BSC 2004 [DIRS 170008]), the flow is primarily through the 
fracture network instead of the matrix. Furthermore, at the scales of interest (hundreds of meters 
to kilometers), the fracture networks appear to be well-connected over large distances. The 
drawdown response to pumping at wells surrounding the C-Wells complex in multiwell pump 
tests indicates a well-connected fracture network in the Miocene tuffaceous rocks in this area 
(Geldon et al. 1997 [DIRS 100397]; Geldon et al. 1998 [DIRS 129721], p. 31; BSC 2004 
[DIRS 170010], Section 6.2). In addition, Finsterle (2000 [DIRS 151875]) demonstrated through 

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ANL-NBS-MD-000002 REV 03 6-8 November 2004 
the comparison of continuum models and discrete fracture models that the continuum approach 
is valid for predicting long-term average seepage rates. These findings support the use of the 
continuum approach to simulate groundwater flow in fractured rocks in the SZ, a larger scale 
process than drift seepage and, thus, more accurately represented as a continuum. 
Therefore, a continuum approach was adopted to simulate groundwater flow through the 
fractured rock in the SZ. Several continuum approaches are available, including single 
continuum, dual porosity, and dual permeabilitydual porosity. The single continuum approach 
is the porous media approach. The dual porosity approach simulates the flow of water in the 
fractures, but allows for interaction by diffusion with the water in the matrix. In this case, the 
matrix acts as a large storage reservoir for water and solutes. This method is useful for 
simulating flow and transport in fractured media where the permeability of the matrix is much 
less than in the fractures, as is the case for fractured tuff units in the SZ. From a flow 
perspective, steady-state flow in fractured media could be successfully simulated with a single 
continuum approach. However, considerations of transport processes, primarily matrix 
diffusion, require the implementation of a dual porosity effective continuum approach in 
fractured tuff in the SZ (BSC 2004 [DIRS 170036], Section 6.3). 
As discussed in Probability Distribution for Flowing Interval Spacing (BSC 2004 
[DIRS 170014]), only a subset of existing fractures is observed to transmit flow in the SZ. The 
hydrogeologic characteristics of these flowing fractures zones vary from borehole to borehole. 
In the SZ transport abstraction model and the one-dimensional transport model, (both discussed 
in Saturated Zone Flow and Transport Model Abstraction [BSC 2004 (DIRS 170042), 
Sections 6.3.1 and 6.3.2]), variability in the groundwater specific discharge, due to variability in 
fracture permeability and orientation, is modeled by scaling the base-casespecific discharge 
flow field (BSC 2004 [DIRS 170037], Section 8.3.1) with the stochastically sampled scaling 
parameters for groundwater specific discharge (GWSPD), and horizontal anisotropy in the 
volcanic units (HAVO). 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: GWSPD, flowing interval spacing in the 
volcanic units (FISVO), flowing interval porosity (FPVO) in the volcanic units, longitudinal 
dispersivity (LDISP), HAVO, colloid retardation factors in the volcanics (CORVO), and the 
radionuclide sorption coefficients between the rock surfaces (which implicitly includes fracture 
linings and brecciated-fractured zones in the volcanic units) for the radionuclides Pu and Cs 
(Kd_Pu_Vo and Kd_Cs_ Vo) and Am, Th, and Pa (collectively modeled with the parameter 
Kd_Am_ Vo). The above parameters are described in Saturated Zone Flow and Transport 
Model Abstraction (BSC 2004 ([DIRS 170042], Sections 6.5.2.1, 6.5.2.4, 6.5.2.5, 6.5.2.9, 
6.5.2.10, 6.5.2.11, and 6.5.2.12 and Table 6-8). 
Supporting Reports: 
 Hydrogeologic Framework Model for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170008]) 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-9 November 2004 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]). 
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 specifically in the repository area. Faults may represent an 
alteration of the rock permeability and continuity of the rock mass, an 
alteration or short-circuiting of the flow paths and flow distributions 
close to the repository, and/or unexpected pathways through the 
repository. 
Screening Decision: Included 
Screening Argument: N/A 
TSPA Disposition: 
Geologic features and hydrostratigraphic units are explicitly included in the Saturated Zone Flow 
and Transport Model Abstraction (BSC 2004 [DIRS 170042]), Section 6.3.1) in a configuration 
that accounts for the effects of existing faults based on the hydrogeologic framework model 
(BSC 2004 [DIRS 170008]). As discussed in Saturated Zone Site-Scale Flow Model (BSC 2004 
[DIRS 170037], Section 6.5.3.1) and Hydrogeologic Framework Model for the Saturated Zone 
Site-Scale Flow and Transport Model (BSC 2004 [DIRS 170008]), the hydrogeologic framework 
model 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 the hydrogeologic framework 
model (BSC 2004 [DIRS 170008]) and accounts for fault dip, strike, slip, and detachment. The 
hydrogeologic properties of these discrete features are developed in Saturated Zone Site-Scale 
Flow Model (BSC 2004 [DIRS 170037], Section 6.3.2). 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. Hydraulic testing in the volcanic units of the saturated zone has 
investigated large volumes of the aquifer, assessing the anisotropy in permeability, which may be 
influenced by faults (BSC 2004 [DIRS 170010], Section 6.2.6). Faults in the SZ site-scale flow 
model domain with an apparent impact on groundwater flow and necessary to achieve flow 
model calibration were explicitly included in the model. Numerous faults occur near Yucca 
Mountain, and some of these faults greatly affect groundwater flow patterns because they may 
act as preferred conduits or barriers to groundwater flow (BSC 2004 [DIRS 170037], 
Section 6.3.2). Additionally, faults can enhance dispersion caused by their affecting 
heterogeneities in permeability along SZ flow paths (BSC 2004 [DIRS 170036], Section 6.3). 
Important thrust faults were represented by repeating hydrogeologic units in the hydrogeologic 
framework model (BSC 2004 [DIRS 170037], Section 6.5.3.1). 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-10 November 2004 
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 HAVO and 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 HAVO and 
GWSPD parameters are described in Saturated Zone Flow and Transport Model Abstraction 
(BSC 2004 [DIRS 170042], Sections 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 following Supplemental 
Discussion for this FEP in the SZ FEP report. 
Supporting Reports: 
 Hydrogeologic Framework Model for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170008]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]). 
Supplemental Discussion: 
Faults fall under several distinct categories based on their hydrological impact on SZ flow paths 
and distributions (BSC 2004 [DIRS 170037], Table 6-6). A list of the modeled faults also 
denoted as features in Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037], 
Section 6.5.3.4), aggregated under their hydrologic categories, is given below. Note in the 
Supplemental Discussion of FEP 2.2.07.13.02AWater Conducting Features in the SZ, a list of 
features, including faults, developed in Saturated Zone Site-Scale Flow Model (BSC 2004 
[DIRS 170037]) is given accompanied by a figure (Figure 6.2-3) 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 Claim Canyon and terminating near Highway 95, 
almost halfway between Solitario Canyon and the western boundary of the SZ 
site-scale model. Vertically, it extends from the top to the bottom of the model. 
- Solitario Canyon Fault ZoneThis is a north-south trending linear feature just to 
the west of Yucca Mountain. Vertically, it extends from the bottom to the top of 
the model. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-11 November 2004 
- Solitario Canyon Fault, East Branch This is a north-northeast trending linear 
feature just to the east of Yucca Mountain. 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 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 fault, east by the Paintbrush Canyon 
fault, and to the north by the Drill Hole Wash fault. Vertically, it extends from 
the top of the model down through the middle volcanics to the top of the 
undifferentiated units. 
6.2.3 Igneous Activity Changes Rock Properties (1.2.04.02.0A) 
FEP Description: Igneous activity near the underground facility may cause 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. 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
Volcanism and igneous activity within the Yucca Mountain region have undergone two 
developmental phases. Silicic volcanism was dominant between 11 million and 15 million years 
ago (Ma), 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 volcanism within the Yucca Mountain region commenced during the later 
part of the caldera-building phase, around 9 Ma. Postcaldera building basaltic igneous activity 
within the Yucca Mountain peaked approximately 7 Ma. Volcanism and igneous activity within 
the Yucca Mountain region are now in a relatively quiescent phase; future igneous activity in the 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-12 November 2004 
Yucca Mountain region will be basaltic in origin (BSC 2004 [DIRS 169989], Section 6.2). The 
reduction in igneous activity is coupled with a reduction in basaltic intrusions within SZ 
stratigraphic units. Thus, on a regional scale, particularly within the next 10,000 years, 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 11 million to 13 million years. 
Uncertainty exists regarding the impacts of past basaltic intrusions on the SZ site-scale 
groundwater flow system, but no such features have been explicitly identified as having an 
impact on the calibration of the SZ site-scale flow model (BSC 2004 [DIRS 170037]). 
Basaltic intrusions due to igneous activity would be an unlikely event, and if one occurred, it 
would be highly localized, causing minimal to localized changes in the hydrogeologic and 
physical properties (e.g., lower permeability of the intrusion relative to the matrix of the 
nonwelded units) of the intruded (country) rock. This is supported by investigations at the 
Grants Ridge analogue site, which indicates that basaltic intrusion produced only localized 
formation of volcanic glass within the contact zone (CRWMS M&O 1998 [DIRS 105347], 
Section 5, p.74). Investigations of basaltic intrusions at Paiute Ridge (Carter Krogh and 
Valentine 1996 [DIRS 160928], pp. 7 to 8) suggest that igneous activities altered rock properties 
from only a few tens of centimeters to, at most, a meter perpendicular to an intruding dike. 
Because 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 unsaturated zone (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 analogue site, 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 multikilometer scale changes in path length that result 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 SZ flow and transport model abstraction 
(BSC 2004 [DIRS 170042], Section 6.3). The SZ flow and transport model evaluates 
uncertainties assigned to flowing interval properties, such as HAVO, flowing interval spacing, 
FPVO in the volcanics, and longitudinal dispersion (BSC 2004 [DIRS 170042], 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 
[DIRS 166335]). The uncertainty incorporated in the horizontal anisotropypartially a function 
of maximum and minimum stresses imposed on fracture and fault orientations (Faunt 1997 
[DIRS 100146]; BSC 2004 [DIRS 170010], Section 6.2.6)results in transport paths varying by 
several kilometers (BSC 2004 [DIRS 170042], 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. 
An intruding dike could potentially affect horizontal anisotropy. The range of dike widths within 
the Yucca Mountain vicinity is projected to be log-normal distributed, having a minimum of 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-13 November 2004 
0.5 m, a mean of 1.5 m, and a 95th percentile of 4.5 m (DTN: LA0407DK831811.001 
[DIRS 170768]). Relative to the large scale of the areally extensive SZ flow and transport 
domain (approximately 1,350 km2), the predicted widths of the contaminant plume flow path, 
ranging between 100 to 1000 m (BSC 2004 [DIRS 170042], Figure 6-6), and the relatively small 
dike width dimensions would cause minimal to localized changes in the hydrogeologic properties 
of the intruded rocks (e.g., lower permeability of the intrusion relative to the matrix of the 
nonwelded units). Given the scale of the SZ flow and transport 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 Saturated Zone Flow and Transport Model Abstraction 
(BSC 2004 [DIRS 170042], Table 6-8), highly localized effects caused by igneous activity will 
not have significant impacts on the flux at the compliance boundary. More specifically, the large 
uncertainty in horizontal anisotropy modeled in the site-scale flow domain overwhelms any 
small scale changes in anisotropy due to future dike intrusions. As a result, 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 the RMEI. A more detailed discussion of FEPs 
related to igneous activity is given in Features, Events and Processes: Disruptive Events 
(BSC 2004 [DIRS 170017], 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 
radiation exposure to the RMEI or radionuclide releases to the accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
The probability of a volcanic eruption intersecting the repository is approximately 1.3 x 10-8 per 
year (BSC 2004 [DIRS 169989], Section 7.1). The probability of such an eruption occurring, 
and intersecting the repository during the first 10,000 years of waste emplacement is 
approximately 1.3 x 10-4 (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. For this exercise, it is assumed six waste commercial spent 
nuclear fuel (CSNF) packages are considered to be entrained in the volcanic eruption, which is 
the estimated median number of packages brought to the surface by a single volcanic eruption 
intersecting one drift (BSC 2004 [DIRS 170001], Section 7.2; DTN: SN0402T0503303.004 
[DIRS 167515]). It is assumed that all of the waste is uniformly distributed in the ash blanket on 
the ground surface. Given these imposed conditions, the resulting estimated annual dose is 
20.5 mrem/year. The resulting probability-weighted annual dose due to leaching of 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-14 November 2004 
radionuclides from contaminated ash becomes less than 2.7 x 10-3 mrem/year (as calculated in 
the Supplemental Discussion for this FEP). 
In addition, the conservative assumption is made that all radionuclides derived from the volcanic 
ash blanket are captured in the communitys hypothetical pumping wells. This is significantly 
less than the probability-weighted doses resulting from other igneous pathways during this 
period (CRWMS M&O 2000 [DIRS 153246], Section 4.2). The effects of nonuniform 
distribution of the ash blanket are addressed in the following Supplemental Discussion. The 
effects of ashfall on SZ transport are excluded on the basis of low consequence because ashfall 
will not significantly change radiation exposure to the RMEI or radionuclide releases to the 
accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
Supplemental Discussion: 
For this screening analysis, the contents of six waste packages are considered to be entrained in 
the volcanic eruption and 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 2004 
[DIRS 170001], Section 7.2; DTN: SN0402T0503303.004 [DIRS 167515]). 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 
communitys hypothetical pumping wells. 
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. Per requirements given in 10 CFR 63 
(DIRS 156605), the same groundwater volume that is used to determine the radionuclide 
concentration in the TSPA-LA for groundwater and individual protection, 3,000 acre ft 
(10 CFR 63, Subparts 63.312 (c) and 63.332 (a)(3)), is used in this analysis to calculate 
concentration for evaluating dose to the RMEI. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-15 November 2004 
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 
[DIRS 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 (BSC 2004 [DIRS 170015], Table 6-2). 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: GS010308312332.002 [DIRS 154734]). The average transport time from the ground 
surface to the water table for radionuclides is calculated as: 
q 
z R t m 
f 
. 
= 
(Eq. 6-1) 
where t is the average transport time [T], Rf is the retardation factor in the alluvium 
[dimensionless], z is the depth to the water table [L], .m is the moisture content [dimensionless], 
and q is the recharge flux [L/T]. The retardation factor for flow in the UZ is defined by Freeze 
and Cherry (1979 [DIRS 101173], p. 404) as: 
f 
. d b 
f 
K R + =1 (Eq. 6-2) 
where .b 
is the dry bulk density of the alluvium [M/L3], Kd the sorption coefficient (which is the 
ratio of the contaminant mass in a unit volume of solution per contaminant mass sorbed on a unit 
mass of solid) [L3/M], and f is the total porosity of the alluvium [dimensionless]. The value of 
bulk density used in the analysis is 1.91 g/milliliter (g/mL) and the porosity is 0.3, which are the 
expected values (BSC 2004 [DIRS 170042], Table 6-8). The median values for the sorption 
coefficients for the radionuclides, as taken from Saturated Zone Flow and Transport Model 
Abstraction (BSC 2004 [DIRS 170042], Table 6-8), are shown in 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 the report by 
Domenico and Schwartz (1990 [DIRS 100569], Equation 14.11), is: 
) 2 ( 5 . 0 
0 
T 
t 
A A 
- 
= (Eq. 6-3) 
where A is the activity at the water table [Curies], A0 is the activity in the ash [Curies], T0.5 is the 
half-life of the radionuclide, and t is the average transport time. Substituting Equations 6-1 and 
6-2 into Equation 6-3 yields the activity of each radionuclide at the water table in Curies. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-16 November 2004 
Note that the isotopes 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 2004 [DIRS 170042], 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. An 
approximate transport time of 800 years for a nonsorbing 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 2004 [DIRS 170042], Figure 6-28). The 
800-year transport time is the approximate median transport time among the multiple realizations 
of SZ transport. The resulting idealized radionuclide mass breakthrough curve (BTC) 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 BTC is 800 years, at which time the most upstream of the radionuclide mass arrives. The 
average (and also peak) concentration of the nonsorbing 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 approximately 1,600 years, and the radionuclide mass flux is one-half of that for 
the nonsorbing species. 
Ash 
Withdrawal 
Well 
SZ 
UZ 
NOTE: SZ=Saturated Zone; UZ=Unsaturated Zone. 
Figure 6.2-1. Schematic Cross Section Diagram of Simplified One-Dimensional Model for Transport in 
the SZ of Radionuclides Leached from Volcanic Ash 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-17 November 2004 
1600 
Time (years) 
Retardation 
Factor = 2.0 
800 
Relative Radionuclide 
Mass Flux 
Non-Sorbing 
Case 
NOTE: For illustration purposes only. 
Figure 6.2-2. Example of Idealized Radionuclide Mass BTCs at 18-km Distance Resulting from Volcanic 
Ash Leaching for Nonsorbing and Sorbing Radionuclides 
The estimate of annual dose 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 transport 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 expected annual dose is calculated as the product of the 
average concentration and the biosphere dose conversion factor for each radionuclide, as shown 
in Table 6.2-1. The values of the biosphere dose conversion factor for these radionuclides are 
taken for present climatic conditions, which are higher than the values for future, wetter 
conditions. The resulting estimated dose is higher and conservative relative to estimated future 
conditions for most of the next 10,000 years. 
The resulting estimated conditional total annual dose is 20.5 mrem/year. As shown in 
Table 6.2-1, the calculated annual dose 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 annual dose is from 239Pu (17.7 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. 
This conditional annual dose 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 (2004 [DIRS 169989], Section 7.1) concludes 
that the mean annual frequency of igneous intrusion into the repository footprint is 1.7 x 10-8. 
The probability of eruption, conditioned to an intrusion, is less, 1.3 x 10-8 (not all hypothetical 
igneous intrusions would result in an eruption at the repository). Adopting the 1.3 x 10-8/year 
value and assuming that future igneous activity at Yucca Mountain is a Poissonian process, there 
is approximately a 1.3 x 10-4 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 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-18 November 2004 
period, and the probability that the event has already occurred (and that groundwater is 
contaminated) rises from 1.3 x 10-8 in the first year to 1.3 x 10-4 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 for site recommendation for doses incurred by direct exposure to a 
contaminated ash layer (CRWMS M&O 2000 [DIRS 153246], Section 4.2). However, it is 
conservative to assume that the annual dose 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 1.3 x 10-4, 
which yields a probability-weighted annual dose of approximately 2.7 x 10-3 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 of about 0.08 mrem/year (CRWMS M&O 2000 
[DIRS 153246], Section 4.2). Although the analyses of the igneous expected annual dose are 
being reevaluated for the TSPA-LA, it is unlikely that the conditional dose from leaching of 
contaminated ash would be a significant contributor to simulated annual dose, particularly 
considering the conservative nature of the simplified analysis presented here. 
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 annual dose 
from the production of contaminated groundwater. The increase in the estimated peak annual 
dose 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 annual dose would be about five times 
greater. This would be a significant increase relative to the estimated conditional annual dose 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, leaching from radionuclide-laden ash fall is excluded from the SZ on the basis of 
low consequence because it will not significantly change radiation exposure to the RMEI or 
radionuclide releases to the accessible environment. 

ANL-NBS-MD-000002 REV 03 6-19 November 2004 
Features, Events, and Processes in SZ Flow and Transport 
Table 6.2-1. Screening Estimate of Dose from the SZ for Leaching from Volcanic Ash, Conditional on Eruptive Release 
Radionuclide 
Curies per 
Packagea 
Curies 
Releaseda 
Expected 
Kd 
(mL/g)b 
Expected 
Rf 
Half-Life d 
(years) 
Curies at 
Water 
Table 
Water 
Volume (L) 
Concentration 
(pCi/L) 
BDCF 
(mrem/year 
per pCi/L)c 
Annual Dose 
(mrem/year) 
14C 6.12  100 3.67  101 0.0 1.0 5.73  103 2.12  101 2.96  1012 7.16  100 9.06  10-3 6.49  10-2 
90Sr 3.48  105 2.09  106 210.0 1338.0 2.91  101 0.00  100 3.96  1015 0.00  100 1.64  10-1 0.00  100 
99Tc 1.29  102 7.74  102 0.0 1.0 2.13  105 7.36  102 2.96  1012 2.49  102 2.21  10-3 5.50  10-1 
129I 3.09  10-9 1.85  100 0.0 1.0 1.57  107 1.85  100 2.96  1012 6.25  10-1 3.37  10-1 2.11  10-1 
137Cs 5.19  105 3.11  106 728.0 4635.9 3.00  101 0.00  100 1.37  1016 0.00  100 4.87  10-1 0.00  100 
232U 2.27  10-1 1.36  100 4.6 30.3 7.20  101 0.00  100 8.97  1013 0.00  100 5.78  100 0.00  100 
233U 5.61  10-4 3.37  10-3 4.6 30.3 1.59  105 1.85  10-3 8.97  1013 2.06  10-5 1.74  100 3.58  10-5 
234U 1.10  101 6.60  101 4.6 30.3 2.45  105 4.48  101 8.97  1013 4.99  10-1 1.21  100 6.04  10-1 
236U 2.51  100 1.51  101 4.6 30.3 2.34  107 1.50  101 8.97  1013 1.67  10-1 1.08  100 1.80  10-1 
238U 2.66  100 1.60  101 4.6 30.3 4.47  109 1.60  101 8.97  1013 1.78  10-1 1.08  100 1.92  10-1 
237Np 3.26  100 1.96  101 6.4 41.7 2.14  106 1.84  101 1.24  1014 1.48  10-1 6.92  100 1.02  100 
238Pu 2.64  104 1.58  105 N/A 34.0 8.77  101 0.00  100 1.01  1014 0.00  100 4.67  100 0.00  100 
239Pu 2.71  103 1.63  104 N/A 34.0 2.41  104 1.95  102 1.01  1014 1.93  100 9.16  100 1.77  101 
240Pu 4.73  103 2.84  104 N/A 34.0 6.54  103 2.35  10-3 1.01  1014 2.33  10-5 8.93  100 2.08  10-4 
241Am 2.84  104 1.70  105 N/A 34.0 4.32  102 0.00  100 1.01  1014 0.00  100 6.78  100 0.00  100 
243Am 2.51  102 1.51  103 N/A 34.0 7.38  103 8.01  10-4 1.01  1014 7.93  10-6 9.43  100 7.48  10-5 
Total estimated conditional dose 20.5e 
NOTE: The probability of eruptive release of radionuclides is about 1.3 x 10-8/year (BSC 2004 [DIRS 169989], Section 7.2). 
a Source: BSC 2004 (DIRS 170022), calculated from Table 7-1 and Appendix III. 
b Source: BSC 2004 (DIRS 170042), Table 6-8. 
c Source: DTN: MO0307MWDNPBDC.001 [DIRS164615], Table 6.2-5. 
d Source: Eckerman and Ryman 1993 [DIRS 107684], Table A-1. 
e Estimated conditional annual dose. 
BDCF=biosphere dose conversion factor 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-20 November 2004 
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. 
Screening Decision: ExcludedLow consequence 
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 volcanism and 
caldera building and basaltic volcanism 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 (BSC 2004 [DIRS 170037] Appendix A, Figure A6-3); all three 
past hydrothermal areas are not along the SZ flow path and lie north and northeast of Yucca 
Mountain (BSC 2004 [DIRS 169989], Figure 6-1). 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 2004 [DIRS 169989], Figure 6-1). None of the three 
past hydrothermal areas are along the SZ flow path from the repository to the RMEI, and all 
three areas lie north and northeast of Yucca Mountain. Hydrothermal mineral replacement is 
distinguished from deuteric alteration. Deuteric alteration, as tuff cools, causes exsolving 
gaseous and aqueous components precipitating opal, calcite, and zeolites in lithophysae and 
intermittent veins (BSC 2004 [DIRS 169734], Section 3.3). Deuteric, not hydrothermal, mineral 
alteration is ubiquitous in the vicinity of Yucca Mountain. 
The likelihood of future hydrothermal activity to develop within the vicinity of SZ flow paths is 
conditioned to future volcanic and igneous activity. Volcanic activity and igneous intrusions in 
the areally extensive Yucca Mountain region, once extensive in nature, are now in a relatively 
quiescent phase (BSC 2004 [DIRS 169989]). Silicic volcanism was dominant in the region 
between 11 and 15 Ma, coincident with plate extension and an episode of major caldera 
formation in the Great Basin region. Crustal extension rates started to decline about 13 Ma; this 
progression in crustal evolution resulted in silicic volcanism being replaced with basaltic 
volcanism. Basaltic volcanism within the Yucca Mountain region commenced during the later 
part of the caldera-building phase, around 9 Ma Postcaldera building basaltic igneous activity 
within Yucca Mountain peaked approximately 7 Ma and is now in a declining state. These 
intruding dikes could induce alteration of the in situ mineralogy adjacent to the intruded rock 
(i.e., the contact zone). 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 2004 [DIRS 169989], Section 6.3.2). Therefore, mineral alteration in this contact 
zone will be minimal. This is supported by investigations at the Grants Ridge analogue site, 
which indicates that basaltic intrusion produced only localized formation of volcanic glass within 
the contact zone (CRWMS M&O 1998 [DIRS 105347], Section 5, p. 74). Investigations of 
basaltic intrusions at Paiute Ridge (Carter Krogh and Valentine 1996 [DIRS 160928], pp. 7 to 8) 
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. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-21 November 2004 
Studies of two-phase fluid inclusions in the UZ at Yucca Mountain using petrography, 
microthermometry, and U-Pb dating indicate that temperatures have remained close to the 
current ambient values over the past 25 million years (Wilson et al. 2003 [DIRS 163589], 
Section 8). These findings show that significant or widespread hydrothermal activity has not 
occurred in the UZ in the recent geologic past, and suggest that hydrothermal activity has been 
absent from the nearby SZ. 
Radionuclide transport processes in the SZ could potentially be impacted by intrusion of igneous 
dikes by the alteration of sorption characteristics of the tuff aquifer. These alterations could 
include mineralogical changes and changes of sorption coefficient values in response to elevated 
temperatures. As noted above, mineralogical changes would be localized around potential future 
igneous intrusions and would not affect a significant portion of the entire volume of the tuff 
aquifer. Elevated temperatures near dikes would also be localized and data on sorption 
coefficients indicate little statistical variation for temperatures up to 80oC (BSC 2004 
[DIRS 170036], Appendix A). 
Given the lack of evidence of any past hydrothermal activity along the Crater Flat basin 
(BSC 2004 [DIRS 170037], Appendix A, Figure A6-3), coupled with the relatively small widths 
of igneous intrusions that would intersect the SZ flow domain and small interfacial zone where 
the in-situ rocks mineralogy is thermally altered, it is inferred that any associated hydrothermal 
activity produced from future igneous activity will be 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 radiation exposure to the RMEI or 
radionuclide releases to the accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. Large-scale dissolution is a potentially important process in rocks 
that are composed predominantly of water-soluble evaporite minerals, 
such as salt. 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
Large-scale dissolution can be excluded from the SZ flow and transport models because 
evaporites, in particular halite with a solubility of 360,000 mg/L at 1 atmosphere (atm) pressure 
and 25C (Freeze and Cherry 1979 [DIRS 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 [DIRS 100131]; BSC 2004 [DIRS 170008], Figures 6-1 and 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 90500 mg/L, depending on the pCO2, at 1 atm pressure and 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-22 November 2004 
25C (Freeze and Cherry 1979 [DIRS 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 (BSC 2004 [DIRS 170037], Section 6.6.2.3), which 
largely consists of disaggregated tuffaceous rocks (BSC 2004 [DIRS 170036], Appendix A, 
Section A8). The carbonate units are included in the SZ flow and transport model, and the 
assigned permeabilities are representative of the existing solution channels and fractures. The 
carbonate units along the SZ transport pathways are located well below the water table 
(BSC 2004 [DIRS 170008], Figures 6-1 and 6-18) along the SZ flow path. 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 (BSC 2004 [DIRS 170037], Section 6.6.2.3). 
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. The volcanic units in the 
vicinity of Yucca Mountain are primarily comprised of silica (quartz and cristobalite), alkali 
feldspars, and zeolites (BSC 2004 [DIRS 170036], Appendix A, Section A2). The solubility of 
quartz is 12 mg/L at 1 atm pressure and 25C (Freeze and Cherry 1979 [DIRS 101173], p. 106), 
and is relatively low compared to evaporites and carbonate solubilities. 
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 
(BSC 2004 [DIRS 170008], Figures 6-1 and 6-18). 
Anthropogenic water table declines within the Yucca Mountain vicinity have been insignificant. 
In the Jackass Flats hydrographic basin, current groundwater withdrawal rates and their effects 
on water table elevations are insignificant (La Camera et al. 1999 [DIRS 103283], 
pp. 17 through 22; Young 1972 [DIRS 103023]). 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. 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. In conclusion, 
large-scale dissolution is excluded based on low consequence because it will not significantly 
change radiation exposure to the RMEI or radionuclide releases to the accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-23 November 2004 
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. 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
Within the Basin and Range Province (which includes the Yucca Mountain region), peak 
extensional stresses occurred between 10 and 12 Ma with extension rates between 10 and 
30 mm/year (National Research Council 1992 [DIRS 105162], Chapter 2). These rapid 
extension rates formed two major north trending extension belts and normal faulting zones. 
Approximately 5 Ma, regional extensional stress declined to 5 to 10 mm/year; extension rates are 
still in a declining state today (National Research Council 1992 [DIRS 105162], Chapter 2). It is 
the extensional stresses imposed on the areally broad Basin and Range Province that impart the 
extension, compression, and shear stresses on the crust, and determine seismic activity that can 
produce faults, fault slip, fracture formation, and fracture connectivity. The type of stress 
transmitted locally is dependent on location, depth, and juxtaposition of existing faults and 
fractures. These locally imposed stresses, which control existing hydrological properties 
(BSC 2004 [DIRS 170037], Section 6.3.2.10), are driven by the crustal (and now declining) 
extension rates. 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 pressure, 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 
[DIRS 170017], 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). 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. A transient change in water table elevations is associated with the passage of a 
seismically perturbed surface wave that passes through the region. 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. Because seismic activity is closely associated with tectonic 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-24 November 2004 
activity, a decline in tectonic activity coincides with a decline in the frequency and intensity of 
seismic activity. 
Investigations of analogue sites and numerical studies demonstrate future 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 (CRWMS M&O 1998 [DIRS 103731], 
Section 8) determined mean displacement in intact rock in the area between Solitario Canyon 
and the Ghost Dance faults to be less than 0.1 cm for a 1x10-8 annual exceedance probability. 
This area is along the predicted transport pathway between the repository and the 18-km 
boundary. Given this small predicted displacement, it is inferred 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 estimated a 24 m mean fault 
displacement, at an annual-exceedance probability of 1 x10-8, as the upper limit for the majority 
of faults within the Yucca Mountain region (CRWMS M&O 1998 [DIRS 103731], Section 8.2). 
The exception is the predicted 10-m mean displacement along the Solitario Canyon fault at an 
annual-exceedance probability of 1x10-8 (CRWMS M&O 1998 [DIRS 103731], Figure 8-3). It 
is believed these fault displacements will not create new flow paths or significantly alter 
predicted SZ flow paths for the reasons stated in the following paragraph. 
Several investigations have been conducted to estimate the hydrologic response (i.e., change in 
water table elevations) given predicted fault displacements. One investigation was performed by 
the National Research Council (1992 [DIRS 105162], Chapter 5). 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 is 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 than 50 m. Given the 
National Research 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). 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-25 November 2004 
Several other numerical studies estimate the hydrologic response due to fault displacement. 
Analysis performed by Gauthier et al. (1996 [DIRS 100447], pp. 163 to 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 [DIRS 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 [DIRS 100967]) modeled tectonohydrologic responses based on an earthquake 
associated with a 1 m fault slip. Simulation results predicted 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 
[DIRS 100967], p. 1159). 
Investigations focusing on the potentiometric hydrologic response, given changes in rock 
properties adjacent to a fault, demonstrate that the changes in water table elevation are transient 
and local in nature. This type of hydrologic response is commonly referenced as seismic 
pumping. One such investigation was performed by Carrigan et al. (1991 [DIRS 100967]). 
They modeled a 100-m-wide fracture zone centered on a vertical fault, such that vertical 
permeability was increased by three orders of magnitude. Model results indicate a transient 
water table rise of up to 12 m in the fracture zone given 1 m of fault slip. The above results 
indicate changes in permeability along faults due to fault slippage would produce a short-term 
and transient seismic pumping event and would not change regional flow directions or flow paths 
over the 10,000 year time scale. 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. 
Observed changes in water table elevation, given recorded seismic events, support the 
conclusions drawn from the above numerical studies. OBrien (1993 [DIRS 101276]) analyzed 
water level fluctuations at Yucca Mountain due to earthquakes in the region. Water table 
fluctuations range from 90 cm associated with a 7.5 magnitude earthquake near Landers, 
California (approximately 420 km from Yucca Mountain) to 20 cm for a second quake of 6.6 
magnitude near Big Bear Lake, California (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 water table fluctuation of 40 cm. Water levels in another well 
declined approximately 50 cm over the 3 days following the earthquake; this well returned to 
prequake levels over a period of about 6 months. These observations indicate changes in the 
water table due to seismic events in the outlying vicinity are relatively minor and transient in 
nature. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-26 November 2004 
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 
2.2.06.02.0A-Seismic activity changes porosity and permeability of faults). The existing rock 
properties along these zones of alteration are the cumulative product of a highly active seismic 
past regionally imposed on the Basin and Range Province over many millennia. Given the 
predicted lower frequencies of future seismic events, it is inferred that hydrologic properties in 
these zones of alteration will not be significantly altered. (Detailed discussions on the effects of 
seismic events on rock properties are provided in Features, Events, and Processes: Disruptive 
Events (BSC 2004 [DIRS 170017], Sections 6.2.1.8 to 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 
SZ flow and transport model abstraction (BSC 2004 [DIRS 170042], Section 6.3). The SZ flow 
and transport model abstraction evaluates uncertainties assigned to flowing interval properties 
such as horizontal anisotropy in permeability (HAVO), flowing interval spacing (FISVO), 
flowing interval porosity in the volcanic units (FPVO) , and longitudinal dispersion (BSC 2004 
[DIRS 170042], 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 primarily accounts 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 [DIRS 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 2004 
[DIRS 170042], 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 change in rock properties residing in the zone of alteration. 
Additionally, the evolution of the calibration and validation of the base-case flow field is based 
on parameter uncertainty and model sensitivity to grid discretization. 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 (BSC 2004 [DIRS 170037], Sections 6.5.3.2, 6.6.1, and 7.0). Grid resolution is based 
on systematically running the model using grids of differing resolutions (increased or decreased 
grid discretizations in both the horizontal and vertical direction), then comparing results. 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 exercise, the appropriate grid discretization used in the SZ flow and transport model is 
one using 500 m uniformly spaced grid blocks in the horizontal direction, and 10 m to 550 m 
nonuniformly spaced grid blocks in the vertical direction. 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 grid discretization, coupled with model scale 
and the parameter uncertainty incorporated into the SZ model. (Seismic effects on rock fault 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-27 November 2004 
properties adjacent and within faults and zones are discussed in FEP 2.2.06.02.0ASeismic 
activity changes porosity and permeability of faults.) 
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 (BSC 2004 
[DIRS 170037], Appendix A, Section A7.1.2). 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 2004 [DIRS 170037], Appendix A, A7.1.4). 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 radiation exposure to the RMEI or 
radionuclide releases to the accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: ExcludedLow consequence 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-28 November 2004 
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 (BSC 2004 [DIRS 170012], Section 6.8.4). 
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 analogue 
sites can be used to estimate 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 
[DIRS 106634]). The vents and associated dike system formed within a 
north-northwest-trending extensional graben. The site provides exposures at a variety of depths 
of the system, including remnants of surface lava flows, volcanic conduits, and dikes and sills 
intruded into the in situ tuff rock at depths of up to 300 m. Investigation of the site indicates 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 (Carter Krogh and Valentine 1996 [DIRS 160928], pp. 7 and 8). Of interest, the 
SZ permeability observed in the Yucca Mountain region has been interpreted to have a 
maximum principal permeability direction of approximately north-northeast, which is consistent 
with the fault and fracture orientation (Ferrill et al. 1999 [DIRS 118941], p. 1). Additional 
analyses of uncertainty in potential horizontal anisotropy have determined that the most likely 
direction of maximum principal permeability is approximately north-south (BSC 2004 
[DIRS 170010], Section 6.2.6). Coincidentally, the dike margins are parallel and associated with 
the primary direction of increased or decreased permeability. This parallel to subparallel dike 
orientation to the principal and maximum permeability orientation, coupled with the limited 
volume of rock affected by an intruding dike, indicate that magmatic intrusion (dikes) will not 
significantly affect groundwater flow patterns at the mountain scale, even if the intruding dike 
differs in permeability. 
There are several lines of evidence that support eliminating the effects of an igneous activity on 
long-term changes in water temperature and geochemistry. Thermal transfer from an intruding 
dike to the in situ rock can morphologically change the in situ rock to volcanic glass, and 
provides an indication of affected transfer depths. Analysis of igneous activity at Paiute Ridge 
(CRWMS M&O 1998 [DIRS 105347], Section 5, p. 57) indicates that thermal transfer into 
adjacent rock due to an igneous activity is minimal. Igneous activities at the Grants Ridge site 
produced only localized formation of volcanic glass within the contact zone 
(CRWMS M&O 1998 [DIRS 105347], Section 5, p. 74 referenced in 
DTN: MO0310INPDEFEP.000); evidence of any regional hydrothermal response was absent. 
Additionally, Kuiper (1991 [DIRS 163417], p. 121) 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 analogue sites 
(CRWMS M&O 1998 [DIRS 105347], Section 5, pp. 1 to 2) support the inference that minimal 
chemical and mineralogical alteration will occur (meters to a few tens of meters) at the interfaces 
between intruding dikes and the in situ rock due to future igneous activity within the Yucca 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-29 November 2004 
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 igneous-altered rock would have little impact on the characteristics of SZ water chemistry (see 
FEPs 2.2.08.01.0AChemical characteristics of groundwater in the SZ and 
2.2.08.03.0A-Geochemical 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 Features, 
Events and Processes: Disruptive Events (BSC 2004 [DIRS 170017], Section 6.2.2). 
In summary, 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 be 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 elevation, 
or SZ flow and flow paths. Therefore, the hydrologic response to igneous activity is excluded 
based on low consequence because it will not significantly change radiation exposure to the 
RMEI or radionuclide releases to the accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
The primary process affecting water table elevation is the cyclical and climatically driven 
infiltration through the UZ to the SZ (Szabo et al. 1994 [DIRS 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 100,000150,000-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 [DIRS 100088], Figure 6; Forester et al. 1996 [DIRS 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 (BSC 2004 [DIRS 170037], Appendix A, Section A7.1) 
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). 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-30 November 2004 
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 400600 years. After the interglacial 
climatic interval, warmer and wetter monsoonal climatic conditions are predicted to persist for 
approximately 9001400 years. It is predicted that a cooler and wetter glacial transition climatic 
condition will follow the brief monsoonal period and will persist for about 8,000-8,700 years 
(BSC 2004 [DIRS 170002], Section 7). However, while not predicted in Future Climate 
Analysis (BSC 2004 [DIRS 170002]), 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 [DIRS 108865]). 
Calcite crystals grown below the water table are dense and elongated, having porosities much 
less than 1 percent (Szabo et al. 1994 [DIRS 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 less dense, short, and porous (120 percent porosity); free 
growing (Szabo et al. 1994 [DIRS 100088]); do not fluoresce or phosphoresce, locally display 
orange growth banding; and have single-phase fluid inclusions (Whelan et al. 1998 
[DIRS 108865]). Whelan et al. (1998 [DIRS 108865]) report evidence of calcite crystal growth, 
indicative of unsaturated conditions in fracture openings, located 100300 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 [DIRS 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 [DIRS 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. The rationale for this statement follows. 
Based on the SZ base-case flow calculations, the transport pathways, under current and wetter 
climatic conditions, are confined to the following hydrostratigraphic units: the Crater Flat-Prow 
Pass, Crater Flat-Bullfrog, and Crater Flat-Tram (subunits of the Lower Volcanic Aquifer), the 
Upper Volcanic Confining Unit, the Upper Volcanic Aquifer, the Undifferentiated Valley Fill, 
and the Alluvium. Of these seven units, most transport pathways pass through the Crater 
Flat-Bullfrog hydrostratigraphic unit (BSC 2004 [DIRS 170037], Section 6.6.2.3). The 
collective thicknesses of these units along the potential transport path are well over 300 m 
(BSC 2004 [DIRS 170037], Section 6.5.3.3). The Prow Pass and Bullfrog units are the most 
permeable volcanic units in the flow and transport path (BSC 2004 [DIRS 170037], Table 6-19). 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-31 November 2004 
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 were lowered by as much as 300 m, transport times would be greater 
than transport through all the Crater Flat subunits. 
Given the collective alluvium and valley-fill thickness of 400700 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 reduce 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 Saturated Zone Flow and 
Transport Model Abstraction (BSC 2004 [DIRS 170042], Section 6.5.2.2). 
Additionally, a lowering of the water table would create longer transport pathways through the 
UZ, thus delaying and potentially reducing the total mass of radionuclides reaching the SZ, and 
creating lower hydraulic gradients. Lower gradients in the SZ equate to slower groundwater SZ 
specific discharge rates, which mean longer SZ transport times to the compliance boundary. 
Lastly, paleoclimate records indicate arid climatic conditions are short, relative to wetter 
conditions (Forester et al. 1996 [DIRS 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 70-80 percent of the time (Szabo et al. 1994 [DIRS 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 the other within the last 
10,000 years. One can infer the current water table is now at a low point in the 
150,000300,000 years 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 140300 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 
140300 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 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. 
TSPA Disposition: N/A 
Supporting Reports: N/A 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-32 November 2004 
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 radionuclide release 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. 
Screening Decision: Included 
Screening Argument: N/A 
TSPA Disposition: 
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. The rationale for the use of flux multipliers is based, in part, on the impact a wetter 
climate would have on the current water table elevations measured in wells within the SZ flow 
domain. These water-level measurements are used to derive a potentiometric surface 
representative of current climate conditions within the Yucca Mountain vicinity, as reported in 
Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model 
(BSC 2004 [DIRS 170009], Section 6.4). 
Flux multipliers are incorporated in the convolution integral method (BSC 2004 [DIRS 170042], 
Section 6.5). Flux multipliers scale the base-case SZ radionuclide BTCs, effectively modeling 
the impacts a higher water table would have on transport times to the 18-km boundary 
(BSC 2004 [DIRS 170042], Section 5). 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 2004 [DIRS 170042], 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 Saturated Zone 
Site-Scale Flow Model, (BSC 2004 [DIRS 170037]), which is approximately equal to the upper 
estimate that the water table would rise under the repository given a future glacial transition 
climatic condition. Conservative and sorbing radionuclide BTCs show initial tracer 
breakthrough times (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 edge times for the alternative model domain are well over an order of 
magnitude greater compared to those derived using a flux multiplier (BSC 2004 [DIRS 170036], 
Appendix E and Figures E-1 and E-2). The longer transport times using the alternative model 
are a function of several factors. The higher water table incorporated in the alternative model 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-33 November 2004 
domain enables both types of tracers to pass through less permeable upper volcanic confining 
units, resulting in considerably longer path lengths and transport times. For these simulations, 
longer transport times are due to a combination of several factors. A higher water table 
partitions flow through volcanic units having less effective (fracture) permeability, thus, 
facilitating greater matrix diffusion. Additionally, a higher water table promotes longer flow 
paths through the porous alluvium, equating to longer alluvium transport times. 
Based on the results from this alternative model, which explicitly simulates a higher water table, 
it is assumed the simplified, flux multiplier method results in more rapid radionuclide transport 
to the 18-km boundary than the explicit model. That is, the flux multiplier method does not 
underestimate groundwater transport times given wetter climate conditions. 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. 
Water table rise associated with future climates is explicitly included in the radionuclide 
transport simulations for the UZ. To include this water table rise in the TSPA-LA calculations, 
the water table elevation is instantaneously increased by 120 m in the UZ model domain when 
the climate changes from present-day to monsoon climate. The same water table elevation is 
also used for the glacial-transition climate. This is a conservative approach that uses the 
reasonable upper bound (120 m rise) from several estimates of the water table elevation under 
the repository in the past (BSC 2004 [DIRS 170037], Section 6.4.5). 
Supporting Reports: 
 Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model 
(BSC 2004 [DIRS 170009]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037] 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]). 
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. 
Screening Decision: Included 
Screening Argument: N/A 
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 

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ANL-NBS-MD-000002 REV 03 6-34 November 2004 
incorporated in the current potentiometric surface developed from current water-level 
measurement taken within the Yucca Mountain vicinity and reported in Water-Level Data 
Analysis for the Saturated Zone Site-Scale Flow and Transport Model (BSC 2004 
[DIRS 170009], Section 6.4). Future water management activities, are presumed to be those 
currently in practice as given by regulation 10 CFR Section 63.305 (b) (DIRS 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. 
The Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
assumes the SZ flow domain is a steady state system (BSC 2004 [DIRS 170042], Section 6.3), 
thus, implicitly adopting the impact of future water management activities on the predicted flow 
and transport paths. Water management activities are explicitly included in the biosphere models 
that determine irrigation intensity, and fraction of overhead irrigation, through the biospheres 
fish and plant mathematical submodels that ascertain the potential dose to RMEI. This FEP, 
and its impact on the RMEI, is discussed in the Evaluation of Features, Events and 
Processes(FEPs) for the Biosphere Model (BSC 2004 [DIRS 169826], Section 6.2.9). 
Supporting Reports: 
 Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model 
(BSC 2004 [DIRS 170009]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]). 
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. 
Screening Decision: Included 
Screening Argument: N/A 
TSPA Disposition: 
The effects of wells on the dose to the RMEI are included by assuming all of the radionuclide 
mass that reaches the 18-km accessible environment is intercepted by the community wells 
(BSC 2004 [DIRS 170042] Sections 5 (3) and 6.3.3). For the individual and groundwater 
protection standard concentrations, it is assumed that all radionuclide mass that crosses the 
18-km boundary is dissolved in the 3,000 acre-ft of water per year (in accordance with 10 CFR 
Part 63 Subparts 63.312 (c) and 63.332 (a)(3) [DIRS 156605]). The location of future wells and 
their impact on the potentiometric surface is based on consideration of present well locations 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-35 November 2004 
within the SZ flow domain as reported in Water-Level Data Analysis for the Saturated Zone 
Site-Scale Flow and Transport Model (BSC 2004 [DIRS 170009]). Hydraulic heads in these 
existing wells are used in the calibration process in the site-scale saturated zone base-case flow 
model (BSC 2004 [DIRS 170037], Section 6.6.1). 
Supporting Reports: 
 Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model 
(BSC 2004 [DIRS 170009]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]). 
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. 
Screening Decision: ExcludedLow consequence 
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 (BSC 2004 [DIRS 170025], Section 1.2) are not considered to move from the 
waste packages through the engineered barrier system (EBS) and UZ (BSC 2004 
[DIRS 170012], Section 6.4.4), 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 (degree of roughness) and orientations, and less mobile regions. A 
large particle will move along this 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: 
V 
D D gL 
sv w p 
18 
) ( 2 - 
= 
(Eq. 6-4) 

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ANL-NBS-MD-000002 REV 03 6-36 November 2004 
with the following inputs: 
 Particle diameter (L) of 1 micron (1x10-6 m). 
 Particle density (Dp) of 2,500 kg/m3 (BSC 2004 [DIRS 170025], Appendix I, Section I3). 
 Water density (Dw) of 1,000 kg/m3 at 20C (Streeter and Wylie 1979 [DIRS 145287], 
p. 534). 
 Water dynamic viscosity (V) of 1.005x10-3 Ns/m2 at 20C (Viswanath and Natarajan 1989 
[DIRS 129867], p. 715). 
 Acceleration of gravity (g) is 9.81 m/s2. 
Using the above inputs (appropriate for 20C), the sv order of magnitude is 8x10-7 m/s 
(0.07 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 8x10-7 m/s. This 
is unlikely for several reasons. 
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 20C to 55C, with the majority of temperatures within the 
upper 20C to lower 30C (BSC 2004 [DIRS 170037], Section 7.2.4.1.1). The 
temperature dependent density and viscosity of water for this temperature range will 
result in a higher sv. Viscosity varies most with temperature. Consequently, the 
variability in sv would most dramatically be increased due to the large variability in 
viscosity. 
2. The assumed diameter for colloids adopted in this argument (1 m) is upper bounding. 
Therefore, any particles larger than this upper bound diameter will have a larger sv 
than that determined using Equation 6-4, and more readily settle out of solution. 
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 
volcanic hydrostratigraphic units SZ flow primarily passes through the Crater 
Flat-Bullfrog, Crater Flat-Tram, Crater Flat-Prow Pass, the Upper Volcanic Aquifer, 
and the Upper Volcanic Confining Unit. Of these five volcanic units, the majority of 
SZ flow passes through the Crater Flat-Bullfrog hydrostratigraphic unit (BSC 2004 
[DIRS 170037], Section 6.6.2.3). 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 Crater 
Flat-Bullfrog, Crater Flat-Tram, and Crater Flat-Prow Pass hydrostratigraphic units 
ranges over 3 orders of magnitude (BSC 2004 [DIRS 170037], 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 

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ANL-NBS-MD-000002 REV 03 6-37 November 2004 
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 flow component in two known SZ locations 
shows 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 2004 [DIRS 170037], Table 6-18). 
The elevation of the two measuring points 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 1 x 10-15 m2 
(BSC 2004 [DIRS 170037], Figure 7-4). Converting permeability to hydraulic 
conductivity (at 20C) gives about 10-8 m/s. Multiplying by the vertical gradient 
gives about 2 x 10-10 m/s for the specific discharge. If the effective porosity is 
0.01 (BSC 2004 [DIRS 170042], Section 6.5.2.), the calculated upward velocity is 
2 x 10-8 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 (BSC 2004 [DIRS 170009], Table 6-4); the elevation 
difference between these two wells is 293 m, yielding a gradient of 
.018 (5.3 m/293 m). The mean vertical permeability value for the alluvium is 
2 x 10-13 m2 (BSC 2004 [DIRS 170037], Figure 7-5), which converted to 
hydraulic conductivity (at 20C) gives 2 x 10-6m/s. Multiplying this by the 
vertical gradient gives a specific discharge of 4 x 10-8 m/s. For the alluvium, the 
mean effective porosity is 0.18 (BSC 2004 [DIRS 170042], Table 6-8); dividing 
specific discharge by mean effective porosity gives the upward vertical velocity 
of about 2 x 10-7 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 
(BSC 2004 [DIRS 170006], 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 [DIRS 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 the basis of low consequence 
because (1) no radionuclide bearing particles larger than colloids are introduced into the SZ from 
the UZ (BSC 2004 [DIRS 170012], Section 6.4.4); (2) large particles will not be suspended for 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-38 November 2004 
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 fracture voids along the transport pathway promote both settling and filtering. 
Transport of particles larger than colloids is excluded based on low consequence because it will 
not significantly change radiation exposure to the RMEI or radionuclide releases to the 
accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: Included 
Screening Argument: N/A 
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 2004 [DIRS 170037] 
and BSC 2004 [DIRS 170036]). 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 2004 [DIRS 170037], Section 6.3.2). The hydrogeologic 
subdivisions employed for the TSPA-LA are a synthesis of the hydrogeologic framework model 
(BSC 2004 [DIRS 170008]) and the calibrated Saturated Zone Site-Scale Flow Model 
(BSC 2004 [DIRS 170037], Section 6.5.3). 
In all, there are 19 hydrogeologic units employed in the formulation of the base-case SZ flow 
model (BSC 2004 [DIRS 170037], Section 6.5.3.1), and the SZ flow and transport abstraction 
(BSC 2004 [DIRS 170042], Section 6.3). These same units are modeled in the base-case SZ 
transport model (BSC 2004 [DIRS 170036]), as a result of the transport model being constructed 
from the SZ base-case flow model. The uncertainty in transport parameters specific to 
stratigraphy, such as effective diffusion, matrix porosity, and bulk density are described in 
Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042], 
Sections 6.5.2.6, 6.5.2.18, and 6.5.2.19). 
The 19 hydrogeologic units can be grouped into 5 basic SZ hydrogeologic subdivisions: the 
upper volcanic aquifer, upper volcanic confining unit, lower volcanic aquifer, lower volcanic 
confining unit, and lower carbonate aquifer (BSC 2004 [DIRS 170037], Section 6.3.2). In the 
SZ base-case flow model (BSC 2004 [DIRS 170037], Sections 6.3.2 and 6.5.3.4), major 

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ANL-NBS-MD-000002 REV 03 6-39 November 2004 
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 
11 for the volcanic units (BSC 2004 [DIRS 170037], 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 2004 [DIRS 170042], 
Section 6.5.2). For the fractured volcanic units, uncertainty in the spacing between intervals 
conducting significant quantities of groundwater is assessed in Probability Distribution for 
Flowing Interval Spacing (BSC 2004 [DIRS 170014]). Hydraulic and tracer testing in the 
fractured volcanic hydrostratigraphic units has been conducted in the area downgradient of the 
repository (BSC 2004 [DIRS 170010]). 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 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042], 
Sections 6.5.2, 6.5.2.1, 6.5.2.2, 6.5.2.3, 6.5.2.6, 6.5.2.18 and 6.5.2.19) and Site-Scale Saturated 
Zone Transport (BSC 2004 [DIRS 170036], Section 6.3). 
Supporting Reports: 
 Hydrogeologic Framework Model for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170008]) 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]). 
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. 
Screening Decision: Included 
Screening Argument: N/A 
TSPA Disposition: 
Geologic features and heterogeneous hydrostratigraphic units are explicitly included in the SZ 
Transport Abstraction Model (BSC 2004 [DIRS 170042]) as cells with specific hydrologic 
parameter values in a configuration based on the hydrogeologic framework used in the Saturated 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-40 November 2004 
Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037], Section 6.3.2). Available geologic 
information of rock properties that affect SZ flow and transport in the Yucca Mountain region is 
used to determine the 19 hydrostratigraphic units modeled in the site-scale SZ flow domain 
(BSC 2004 [DIRS 170008]). 
There are numerous broad and distinct zones in the SZ flow model categorized as features, 
which are directly or indirectly affected by faults, zones of mineralogical alteration along faults, 
or contact zones between units (BSC 2004 [DIRS 170037], Section 6.5.3.4, Table 6-6). The 
zones are categorized depending upon how their unique rock property characteristics, most 
notably porosity and permeability, affect flow and transport. The nature of the rock properties in 
these zones causes them to act as either barriers or conduits to SZ flow (BSC 2004 
[DIRS 170037], Section 6.5.3.4, Table 6-6). They are grouped as follows: (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 nonfault 
zones, (4) faults and zones representing regions of lower permeability caused by hydrothermal 
alteration, and (5) zones of unknown features. Details of the 17 modeled features are given in 
the FEP 2.2.07.13.0A-Water-conducting features in the SZ. 
In the Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037], Section 6.5.3), a 
base-case permeability flow field is generated. 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 2004 
[DIRS 170037], 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 one-dimensional transport model (both models 
described in Saturated Zone Flow and Transport Model Abstraction, BSC 2004 [DIRS 170042], 
Section 6.5 and Table 6-2) take the base-case transport model and incorporate additional 
uncertainty, heterogeneities, and potential changes in permeability through the stochastically 
sampled GWSPD (BSC 2004 [DIRS 170042], Section 6.5.2.1). This results in multiple 
heterogeneous permeability fields. Additional uncertainty and spatial variability in rock 
properties in the SZ transport abstraction model are encompassed within uncertainty distributions 
for the following stochastically sampled parameters: (1) HAVO, (2) effective porosity in the 
alluvium units 7 and 19 (NVF7 and NVF19), (3) FISVO, (4) FPVO, (5) alluvium bulk density 
(bulk density), (6) sorption coefficients (Kd) for the 9 classes of radionuclides modeled in both 
the alluvium and volcanic units, and (7) LDISP. The above parameters are described in Sections 
6.5.2.1, 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 the SZ flow and 
transport model abstraction. Uncertainty in the flowing interval spacing parameter is assessed in 
Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]). The basis 
for anisotropy in permeability in the volcanic units and assessment of groundwater specific 
discharge in the alluvium are discussed in Probability Distribution for Flowing Interval Spacing 
(BSC 2004 [DIRS 170010]). Other parameters that effectively model the uncertainty in rock 
parameters are the contact zone between the alluvium and the volcanic units and volcanic and 
alluvium porosities, bulk densities, which are discussed in Sections 6.5.2.2, 6.5.2.14, 6.5.2.15, 
6.5.2.16, 6.5.2.17, 6.5.2.18, 6.5.2.19, and 6.5.2.20 of the SZ flow and transport model abstraction 
(BSC 2004 [DIRS 170042]). The impacts of rock properties on sorption coefficients uncertainty 

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ANL-NBS-MD-000002 REV 03 6-41 November 2004 
are discussed in the Site-Scale Saturated Zone Transport (BSC 2004 DIRS [170036], 
Sections 6.3 and 6.4 and Appendix A). 
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 2004 [DIRS 170042], 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. 
Supporting Reports: 
 Hydrogeologic Framework Model for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170008]) 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]). 
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. 
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 Ma, with estimated extension rates ranging 
between 10 and 30 mm/year (National Research Council 1992 [DIRS 105162], Chapter 2). 
During this period, major faults and fractures within the Yucca Mountain vicinity were created. 
Approximately 5 Ma, regional extension stresses declined to 5-10 mm/year; currently, extension 
rates are still in a declining state (National Research Council 1992 [DIRS 105162], Chapter 2). 
On a local scale, regional extension rates impart local extension, compression, and shear stresses 
on the crust, depending on location, depth, 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 

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ANL-NBS-MD-000002 REV 03 6-42 November 2004 
in pore pressure, 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 in the Yucca Mountain region is most likely to cause movement along existing 
faults and fractures (BSC 2004 [DIRS 170017], 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 offset (Sweetkind et al. 
1997 [DIRS 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 [DIRS 100183], pp. 66 to 71). Existing rock hydrologic properties in the 
zone of alteration reflect the cumulative response of a dynamic seismic past, demonstrative of 
rapid extension rates in existence 1012 Ma, and, to a lesser extent, the lower extension rates in 
effect today. 
Expert elicitation, documented in the PSHA report (CRWMS M&O 1998 [DIRS 103731]), 
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 the vicinity of Yucca 
Mountain, the expert group analyzed nine local fault displacement hazard points they considered 
as representative of repository conditions (CRWMS M&O 1998 [DIRS 103731], Figure 4-9). 
One region of interest 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 [DIRS 103731], 
Zone 8 in Figure 4-9), which is due west of the repository, 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 1  10-8 annual-exceedance probability 
(CRWMS M&O 1998 [DIRS 103731], Section 8). This area encompasses the same rock type as 
that along the origin of the SZ flow and transport 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 1  10-8 
(CRWMS M&O 1998 [DIRS 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 [DIRS 103731], Points 2 and 9 in Figure 4-9), which are block-bounding 
faults and are expected to have higher displacements. The panel predicted approximately a 10 m 
mean fault displacement for the Solitario Canyon fault at an annual exceedance probability of 
1  10-8, and a 7.5 m mean displacement for the Bow Ridge fault at an annual exceedance 
probability of 1  10-5 (CRWMS M&O 1998 [DIRS 103731], Figures 8-2 and 8-3). These 
displacements will not affect SZ transport and flow paths for the following reasons: 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-43 November 2004 
 The Solitario Canyon fault has a cumulative displacement of approximately 260 m where 
it intersects the Enhanced Characterization of the Repository Block (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 [DIRS 170017], 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 Features, Events, and 
Processes: Disruptive Events (BSC 2004 [DIRS 170017], Sections 6.2.1.8 to 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 Saturated Zone Site-Scale Flow 
Model (BSC 2004 [DIRS 170037], Section 6.5.3.4 and Table 6-6). 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 brecciated 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 2004 
[DIRS 170037], Section 6.4.3.2 and Figure 6-7). 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 points 
identified by the PSHA 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 (1992 [DIRS 105162], 
Chapter 5) 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. By 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 than 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 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-44 November 2004 
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. OBrien (1993 [DIRS 101276]) analyzed water level fluctuations at Yucca Mountain 
due to earthquakes. Fluctuations range from 90 cm related to a 7.5 magnitude earthquake near 
Landers, California (approximately 420 km from Yucca Mountain) to 20 cm for a second quake 
of 6.6 magnitude near Big Bear Lake, California (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 at one well, with water levels in another 
well declining approximately 50 cm over the 3 days following the earthquake. Water levels in 
that well returned to prequake 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 than 
5 Ma, 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 are dominated by existing fractures, fracture clusters, 
and fracture spacing collectively labeled as flowing intervals in the SZ flow and transport model 
(BSC 2004 [DIRS 170042], Section 6.3). The SZ flow and transport model evaluates 
uncertainties assigned to flowing interval properties, such as HAVO, flowing interval spacing, 
FPVO in the volcanics, and longitudinal dispersion (BSC 2004 [DIRS 170042], Table 6-8). 
Transport times through the SZ are quite sensitive to parameter uncertainty associated with 
flowing interval properties; only the uncertainty incorporated in the specific discharge scaling 
parameter meant to account for increased infiltration, and a rise in the water table 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 [DIRS 166335]). The uncertainty incorporated in the horizontal anisotropy 
(partially a function of maximum and minimum in situ stresses imposed on fracture and fault 
orientations (Faunt 1997 [DIRS 100146] and BSC 2004 [DIRS 170010], Section 6.2.6) results in 
the suite of transport paths varying by several kilometers from one another (BSC 2004 
[DIRS 170042], 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 radiation exposure to the RMEI 
or radionuclide releases to the accessible environment. 

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ANL-NBS-MD-000002 REV 03 6-45 November 2004 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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 pre-existing faults or generation of new faults, which could 
significantly change the flow and transport paths, alter or short-circuit the 
flow paths and flow distributions close to the repository, and/or create 
new pathways through the repository. These effects may decrease the 
transport times for potentially released radionuclides. 
Screening Decision: ExcludedLow consequence 
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 Ma 
with extension rates between 10 and 30 mm/year (National Research Council 1992 
[DIRS 105162], Chapter 2). These rapid extension rates formed two major north trending 
extension belts and normal faulting zones. Approximately 5 Ma, regional extensional stress 
declined to 5 to 10 mm/year; extension rates are still in a declining state today (National 
Research Council 1992 [DIRS 105162], Chapter 2). It is the extensional 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 (BSC 2004 [DIRS 170037], 
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 future fault formation and displacement within the Yucca 
Mountain region. 
Expert elicitation, documented in the PSHA report (CRWMS M&O 1998 [DIRS 103731]), 
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 
1  10-8 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. 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 1  10-8 (CRWMS M&O 1998 [DIRS 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 [DIRS 103731], Points 2 and 9 in Figure 4-9), which are 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-46 November 2004 
block-bounding faults and are expected to have higher displacements. The panel predicted 
approximately a 10-m mean fault displacement for the Solitario Canyon fault at an annual 
exceedance probability of 1  10-8, and a 7.5 m mean displacement for the Bow Ridge fault at an 
annual exceedance probability of 1  10-5 (CRWMS M&O 1998 [DIRS 103731], Figures 8-2 
and 8-3). As discussed in Features, Events and Processes: Disruptive Events (BSC 2004 
[DIRS 170017], 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 [DIRS 100183]). Generally, the zone of alteration adjacent to the fault is relatively narrow. 
Faults with 1 to 5 m of cumulative offset have a zone of alteration width of only 1-m; faults with 
tens of meters of offset can have a zone of alteration up to tens of meters wide (Sweetkind et al. 
1997 [DIRS 100183], pp. 66 to 71). 
Several studies have been performed to determine changes in water table elevations due to 
seismically induced changes in fault properties, implicitly due to fault offset. Carrigan et al. 
(1991 [DIRS 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 23 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 [DIRS 100967], 
p. 1159). 
Gauthier et al. (1996 [DIRS 100447], pp. 163 to 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 [DIRS 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 14 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 (1992 [DIRS 105162], Chapter 5) on the geologic and 
climatic processes that could affect water table 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. (Seismic pumping is a transient water table rise as a result of a seismic event.) 
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 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-47 November 2004 
(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 upon 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 the approach taken, that the 
maximum water table rise, given a seismic event, would be less than 50 m and transient in 
nature. Because water table fluctuations were transient for both modeling approaches, 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 [DIRS 149850], pp. 48 to 65). 
With this relatively large fault displacement, its zone of alteration consists of an approximate 
20-m brecciated and gouge zone and seismically induced fractured area that extends tens of 
meters from the fault (BSC 2004 [DIRS 170017], 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 10-12 million years incurred in the parent rock and embedded faults within 
the Yucca Mountain region (National Research Council 1992 [DIRS 105162], Chapter 5). It is 
these global and areally extensive stresses imposed on the fault that determine the hydrologic 
properties of the fault, such as permeability and porosity. The logical conclusion that the 
Solitario Canyon faults hydrologic properties will remain essentially unchanged, given an 
approximate 10-m displacement. The fault will continue to serve as a groundwater divide 
between the Yucca Mountain and the Crater Flat regions (BSC 2004 [DIRS 170037], 
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. OBrien (1993 [DIRS 101276]) analyzed water table level 
fluctuations at Yucca Mountain due to earthquakes. Water table fluctuations range from 90 cm, 
related to a 7.5 magnitude earthquake near Landers, California (approximately 420 km from 
Yucca Mountain), to 20 cm for a second quake of 6.6 magnitude near Big Bear Lake, California 
(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 prequake 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, and, by implication, regional flow paths. 
Additionally, the uncertainty in the effective hydrologic properties incorporated in the SZ flow 
and transport model (BSC 2004 [DIRS 170042], Table 6-8), which reflects the cumulative 
changes in a faults hydrologic properties during a heightened seismically active past, coupled 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-48 November 2004 
with the scale of the model (a grid discretized 500 m in the horizontal direction and 10550 m in 
the vertical direction), overwhelms the changes in fault properties, and their effects on flow paths 
and transport times, 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 SZ flow and transport model (BSC 2004 
[DIRS 170042], Section 6.3). The SZ flow and transport model evaluates uncertainties assigned 
to flowing interval properties, such as HAVO, flowing interval spacing, FPVO in the volcanics, 
and longitudinal dispersion (BSC 2004 [DIRS 170042], 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 [DIRS 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 2004 [DIRS 170042], 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 (which 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 [DIRS 170017], 
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 

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ANL-NBS-MD-000002 REV 03 6-49 November 2004 
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. 
In conclusion, changes in fault properties in the SZ can be excluded based on low consequence 
because they will not significantly affect radiation exposure to the RMEI or radionuclide releases 
to the accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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 pre-existing fractures or 
generation of new fractures, which could significantly change the flow 
and transport paths, alter or short-circuit the flow paths and flow 
distributions close to the repository, and/or create new pathways through 
the repository. These effects may decrease the transport times for 
potentially released radionuclides. 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
Fault displacement, and concomitant fracture formation, is a result of regional plate tectonic 
activity that imparts crustal extensional stresses causing rupture of the parent rock. Within the 
Basin and Range Province (which includes the Yucca Mountain region), peak extensional 
stresses were 10-30 mm/year between 10 and 12 Ma (National Research council 1992 
[DIRS 105162], Chapter 2). These rapid extension rates formed two major north trending 
extension belts and normal faulting zones. Approximately 5 Ma, regional extensional stress 
declined to 5-10 mm/year; extension rates are still in a declining state today (National Research 
Council 1992 [DIRS 105162], Chapter 2). It is the extension stresses of the areally broad Basin 
and Range Province that impart 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 (BSC 2004 
[DIRS 170037], 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. 

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ANL-NBS-MD-000002 REV 03 6-50 November 2004 
Expert elicitation documented in the PSHA report predicts less than a 1-cm displacement within 
the vicinity of the repository host rock (between Solitario Canyon and the Ghost Dance faults) at 
a 1  10-8 exceedance probability (CRWMS M&O 1998 [DIRS 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 
and the Bow Ridge faults (block-bounding faults), 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 1  10-8 (CRWMS M&O 1998 [DIRS 103731], 
Section 8.2). Movement on the block-bounding faults may exceed that for intrablock faults. At 
the same low exceedance probability, the panel predicted a 10-m mean fault displacement for the 
Solitario Canyon fault and a 7.5 m mean displacement for the Bow Ridge fault at an annual 
exceedance probability of 1  10-5 (CRWMS M&O 1998 [DIRS 103731], Figures 8-2 and 8-3). 
As discussed in Features, Events and Processes: Disruptive Events (BSC 2004 [DIRS 170017], 
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 
[DIRS 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 [DIRS 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 [DIRS 170017], 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. Brief summaries of their findings follow. 
Carrigan et al. (1991 [DIRS 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 accompanying 
one meter of fault slip (the rise labeled as seismic pumping). The Carrigan study predicts 
short-term water table excursions given 14 m fault slips and attendant alteration of adjacent 
fractures. It is inferred that an approximate 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 (National Research Council 1992 [DIRS 105162]) on the geologic and climatic 
processes that could affect water table elevations. 
The National Research Council addressed the maximum level the water table could rise within 
the next 10,000 years, as a result of several processes, including 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 upon the elastic properties of the bulk rock and the mineral grains. The 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-51 November 2004 
extent of water table fluctuations differed for both models. By 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 that, regardless of what approach is taken, 
the maximum water table rise, given a seismic event, would be less than 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 stresses imposed by a 10 m 
slip along the Solitario Canyon fault, will not alter the regional fracture hydrologic properties. 
These studies suggest seismic pumping due to changes in fracture permeability along faults 
would produce a short-term and transient water table rise. 
The magnitude and transient nature of a predicted water table rise is consistent with observations 
of water table fluctuations, given seismic events. OBrien (1993 [DIRS 101276]) analyzed water 
table fluctuations at Yucca Mountain due to earthquakes. Water table fluctuations range from 
90 cm, related to a 7.5 magnitude earthquake near Landers, California (approximately 420 km 
from Yucca Mountain), to 20 cm for a second quake of 6.6 magnitude near Big Bear Lake, 
California (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 at one well, while water levels in another well declined approximately 
50 cm over the 3 days following the earthquake. Water levels in that well returned to prequake 
levels over a period of about 6 months. 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 SZ flow and transport model 
(BSC 2004 [DIRS 170042], Section 6.3). The SZ flow and transport model evaluates 
uncertainties assigned to flowing interval properties, such as HAVO, flowing interval spacing, 
FPVO in the volcanics, and longitudinal dispersion (BSC 2004 [DIRS 170042], 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 
[DIRS 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 2004 [DIRS 170042], 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 1012 Ma. 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. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-52 November 2004 
Therefore, it is inferred that 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, resulting from seismic activity, are excluded based on low consequence because they 
will not significantly affect radiation exposure to the RMEI or radionuclide releases to the 
accessible environment. 
Additional discussions on the effects of seismic events on rock properties are provided in 
Features, Events, and Processes: Disruptive Events (BSC 2004 [DIRS 170017], 
Sections 6.2.1.8, 6.2.1.9, 6.2.1.10, and 6.2.1.11). 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: Included 
Screening Argument: N/A 
TSPA Disposition: 
Steady-state, saturated, three-dimensional groundwater flow within the Yucca Mountain vicinity 
is modeled in the Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037], 
Section 6.3.1) and the Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036], 
Section 6.3) using the numerical code FEHM. The estimated groundwater flow rates into the SZ 
site-scale flow model domain, both as recharge (infiltration) at the upper boundary (water table) 
and as underflow at the lateral boundaries, are determined from a larger scale regional model and 
reported in Recharge and Lateral Groundwater Flow Boundary Conditions for the Saturated 
Zone Site-Scale Flow and Transport Model (BSC 2004 [DIRS 170015], Section 6) and a much 
smaller scale model, which calculates infiltration from the UZ to the SZ in the area of the 
repository footprint (BSC 2004 [DIRS 170015] Section 6.2.2). The site-scale model domain is a 
30 km by 45 km region within the confines of the Death Valley groundwater basin (BSC 2004 
[DIRS 170037], Section 6.3.2). Inputs include faults and fault zones (BSC 2004 [DIRS 170037], 
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 used in the base-case flow model (BSC 2004 [DIRS 170008]). The 
most significant flow units are the volcanic Crater Flat Tuff hydrogeologic (hydraulic) units and 
the shallow alluvial aquifer of Fortymile Wash. As discussed in the report Probability 
Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]), only a subset of existing 
fractures is observed to transmit flow in the SZ. Flow through fractures is modeled through an 
effective continuum flow model (BSC 2004 [DIRS 170037], Section 6.3.3). Uncertainty in the 
saturated flow through fractures is incorporated in the flow modeling with parameters of flowing 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-53 November 2004 
interval spacing, specific discharge, and the horizontal anisotropy (BSC 2004 [DIRS 170042], 
Sections 6.5.2.1, 6.5.2.4, and 6.5.2.10). Uncertainty in groundwater specific discharge in the 
alluvium is discussed in Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010], Section 
6.5.5). 
Recharge is modeled through underflow, surface flow infiltration, and UZ infiltration 
components. More specifically it includes distributed vertical recharge from the regional-scale 
groundwater flow model, recharge from infiltration of surface water flows in Fortymile Wash, 
and recharge from the UZ site-scale flow model. The UZ infiltration components include an area 
outside of the repository footprint (defined as the distributed UZ infiltration component), and 
infiltration from the more refined discretized area of the repository footprint (BSC 2004 
[DIRS 170037], Section 6.3.2.7). The impact of future climatic conditions on flow are modeled 
in the Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042], 
Sections 6.5 and 6.5.2.1) using a convolution integral method (SZ_Convolute V2.2, 
STN: 10207 2.2-00 software code Sandia National Laboratories 2003 [DIRS 163344]; and 
BSC 2004 [DIRS 170042], Sections 6.5 and 6.5.1) that scales radionuclide BTC simulations 
representing current climatic conditions using representative scaling factors (BSC 2004 
[DIRS 170042], Section 6.5.1). 
Supporting Reports: 
 Recharge and Lateral Groundwater Flow Boundary Conditions for the Saturated Zone 
Site-Scale Flow and Transport Model (BSC 2004 [DIRS 170015]) 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]). 
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. 
Screening Decision: Included 
Screening Argument: N/A 
TSPA Disposition: 
Faults and fractures in the volcanic units are explicitly modeled in the SZ (BSC 2004 
[DIRS 170042]) through 17 discrete geologic features incorporated in the SZ base-case model 
(BSC 2004 [DIRS 170037], Section 6.3.2). The impacts of these various features on SZ 
transport are evaluated in Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036], 
Sections 6.3 and 6.4). The variability and uncertainty due to the presence of fracture clusters, 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-54 November 2004 
flowing intervals, and rubblized zones (all possible subsets of water-conducting features within 
the faulted and fractured system) are modeled in the SZ transport abstraction model and the SZ 
one-dimensional transport model, both described in Saturated Zone Flow and Transport Model 
Abstraction (BSC 2004 [DIRS 170042]). The variability and uncertainty are represented through 
the following stochastically sampled parameters: GWSPD, FISVO, HAVO, FPVO, and LDISP, 
as shown in Section 6.5.2 and Table 6-8 of the SZ flow and transport model abstraction. The 
ranges of uncertainty in these parameters encompass the possibility of channelized flow along 
preferred pathways. The 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 the abstraction. 
Numerous broad and distinct zones in the SZ flow model are categorized as features and, 
depending upon their physical properties, these act as either barriers or conduits to SZ 
groundwater flow. These areas are directly or indirectly affected by faults, zones of 
mineralogical alteration along faults, or contact zones between units (BSC 2004 [DIRS 170037], 
Section 6.5.3.4). In total, there are 17 features defined in the SZ site-scale flow model for Yucca 
Mountain. 
A feature with no known association with a distinct fault or fault zones is also incorporated into 
the SZ flow and transport 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 the cause of the 
large hydraulic gradient, but no one theory is overwhelmingly favored over others. Nevertheless, 
this feature has been incorporated into the model to produce a large hydraulic gradient north of 
the repository. 
All 17 features are distinct from the subhorizontal geologic formations of the hydrogeologic 
framework model (BSC 2004 [DIRS 170008]) in which they reside; most are essentially vertical, 
with some linear in the horizontal extent, and others areally extensive (BSC 2004 
[DIRS 170037], Figure 6-4). Depending upon their hydrologic impact on groundwater flow 
patterns, these features fall under several distinct categories as follows: (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 nonfault 
zones; (4) features, some bordered by faults, representing regions of lower permeability caused 
by hydrothermal alteration and; (5) zones of unknown features (Saturated Zone Site-Scale Flow 
Model (BSC 2004 [DIRS 170037], Table 6-6). A list of the 17 features modeled in Saturated 
Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037], Table 6-6), aggregated under 
hydrologic categories, is given in the supplemental discussion. 
Smaller-scale water conducting features are assessed as flowing intervals in the fractured 
volcanic units, as described in Probability Distribution for Flowing Interval Spacing (BSC 2004 
[DIRS 170014]). In situ testing of smaller scale water conducting features was performed at the 
C-wells complex, as documented in Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]). 
Supporting Reports: 
 Hydrogeologic Framework Model for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170008]) 

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ANL-NBS-MD-000002 REV 03 6-55 November 2004 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Saturated Zone Site-Scale Flow Model(BSC 2004 [DIRS 170037]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]). 
Supplemental Discussion: 
In Figure 6.2-3, a depiction of the 17 discrete features is modeled in the SZ flow and transport 
model and described in detail in the Saturated Zone Site-Scale Flow Model (BSC 2004 
[DIRS 170037], Table 6-6). 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 Claim Canyon and terminating near Highway 95, 
almost halfway between the western boundary of the Solitario Canyon and the SZ 
site-scale model domain. Vertically, it extends from the top to the bottom of the 
model. 
- Solitario Canyon Fault ZoneThis is a 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 Branch This is a north-northeast trending linear 
feature just to the east of Yucca Mountain. Vertically, it extends from the bottom 
to the top of the model. 
- Solitario Canyon Fault, West Branch This is a north-northeast trending linear 
feature just to the west of Yucca Mountain. Vertically, it extends from the 
bottom 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. 

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- Imbricate Fault ZoneThis is a highly faulted area bounded in the west by the 
Ghost Dance fault, to the south by the Dune Wash, to the east by the Paintbrush 
Canyon fault, and to the north by the Drill Hole 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 nonfault 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 ZoneThis north-south linear feature is 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) Zones 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 CalderaThis zone spans 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. Zones These 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. 

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ANL-NBS-MD-000002 REV 03 6-57 November 2004 
535000 540000 545000 550000 555000 560000 
81 
82 
57,58
59 
61,62 63,64 
65,66 
69-72 
74
75 
76 
77 
78
79 
80 
90 
83 
84 
88 
91 
45 
UTM-X (meters) 
56 
535000 540000 545000 550000 555000 560000 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
UTM-Y (meters) 
UTM-X (meters) 
Highway 95 Fault 
Gravity 
Fault 
Bare 
Mountain Fault 
Crater 
Flat Fault 
Specter 
Range 
Thrust Fault 
Windy 
Wash 
Fault 
Paintbrush Canyon 
Fault 
Solitario 
Canyon Fault 
Bow 
RidgeFault 
Dune WashFault 
Ghost Dance 
Claim Canyon 
Caldera Boundary 
Fault 
Splay of 
Calico 
Hills 
Shoshone 
Mountain 
Fatigue Wash 
Fault 
Fortymile 
Wash 
Source: Modified from BSC 2004 (DIRS 170037), Figures 6-4 and 6-6. 
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. 
- Calico Hills Zones These 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, they extend 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 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-58 November 2004 
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. 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
The FEP is excluded based on the bounding and imposed condition that a contaminant plume 
reaches the water table with same density as that of in situ waters, thus, not promoting flow due 
to density gradients. Density gradients due to the introduction of groundwater with higher solute 
concentration and higher density would spread the plume laterally in both the horizontal and 
vertical directions. Lateral spreading would expose the plume to more fracture-matrix interfaces 
in the volcanic units, thus, facilitating matrix diffusion. Additionally, more matrix diffusion 
means the plume is exposed to more sorption sites. These two processes enhance the plumes 
chemical (via sorption) and physical (via matrix diffusion) retardation, thus, increasing the 
plumes transport time to the accessible environment. Consequently, by not considering 
chemically induced density effects, the potential dose to the hypothetical exposed community is 
overestimated and the plume transport times are underestimated. 
The TSPA-LA models calculate the concentration of contaminants in groundwater by capturing 
all of 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 redistribution 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 groundwater (per guidance given in 10 CFR Part 63 Subparts and 63.312 (c) 63.332 
(a)(3) [DIRS 156605]), the potential dose to the hypothetical and exposed community will not be 
underestimated. Including chemically induced density effects 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 of 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. 
TSPA Disposition: N/A 
Supporting Reports: N/A 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-59 November 2004 
6.2.22 Advection and Dispersion in the SZ (2.2.07.15.0A) 
FEP Description: Advection and dispersion processes may affect radionuclide transport in 
the saturated zone. 
Screening Decision: Included 
Screening Argument: N/A 
TSPA Disposition: 
Advection and longitudinal dispersion of dissolved radionuclides are explicitly included in the 
conceptual and mathematical models for TSPA-LA (BSC 2004 [DIRS 170036], Sections 6.3 and 
6.4). The numerical code FEHM implements the 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. The estimated groundwater flow 
rates into the SZ site-scale flow model domain, both as recharge (infiltration) at the upper 
boundary (water table) and as underflow at the lateral boundaries, are determined from a larger 
scale regional model and reported in Recharge and Lateral Groundwater Flow Boundary 
Conditions for the Saturated Zone Site-Scale Flow and Transport Model (BSC 2004 
[DIRS 170015], Section 6). 
FEHM generates the three-dimensional flow field of the SZ site-scale flow model using 
calibrated permeability as input. The base-case specific discharge field is output from the 
Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037], Section 8.2). The base-case 
calibrated permeability field is scaled with the stochastically sampled GWSPD and HAVO 
(BSC 2004 [DIRS 170042], Sections 6.5.2.1 and 6.5.2.10) to produce 200 unique 
three-dimensional 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 2004 [DIRS 170010]); calibration of the 
base-case flow field to measured heads, discussed in Saturated Zone Site-Scale Flow Model 
(BSC 2004 [DIRS 170037], Section 6.6.1); and expert elicitation, discussed in Saturated Zone 
Flow and Transport Expert Elicitation Project (CRWMS M&O 1998 [DIRS 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 Saturated Zone In-Situ 
Testing (BSC 2004 [DIRS 170010], Section 6.2.6) and numerical analysis discussed in Saturated 
Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037], Section 6.5.3). Detailed discussions of 
the scaling parameters GWSPD and HAVO implementation are located in Saturated Zone Flow 
and Transport Model Abstraction (BSC 2004 ([DIRS 170042], Sections 6.5.2.1 and 6.5.2.10). 
Uncertainty in the dispersion tensor is modeled by stochastically varying the input longitudinal 
dispersivity (LDISP) value. This approach is done using the LDISP (BSC 2004 [DIRS 170042], 
Section 6.5.2.9). The range for the LDISP parameter is based on recommendations from the 
expert elicitation panel (CRWMS M&O 1998 [DIRS 100353], Section 3.2), which were used as 
the basis for determining the bounds on the longitudinal dispersivity. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-60 November 2004 
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 Saturated 
Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042], Section 6.5.2.9). 
Supporting Reports: 
 Recharge and Lateral Groundwater Flow Boundary Conditions for the Saturated Zone 
Site-Scale Flow and Transport Model (BSC 2004 [DIRS 170015]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]). 
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. 
Screening Decision: Included 
Screening Argument: N/A 
TSPA Disposition: 
Dilution of radionuclides as a result of pumping is included in the TSPA-LA in two ways 
(BSC 2004 [DIRS 170042]). First, dilution of simulated radionuclide concentrations within the 
contaminant plume is explicitly modeled through the transverse hydrodynamic dispersion 
parameter and caused, in part, by heterogeneities in permeability at all scales (BSC 2004 
[DIRS 170036], Section 6.3). Transverse dispersivity is a function of the stochastically sampled 
LDISP (BSC 2004 [DIRS 170042], Sections 6.7.2 and 6.5.2.9). Secondly, it is assumed in 
Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042], 
Sections 5 (3) and 6.3.3) that all of the radionuclide mass crossing the 18-km regulatory 
boundary is dissolved in the representative volume of water per 10 CFR Part 63 Subparts 63.312 
(c) and 63.332 (a)(3) (DIRS 156605), 3,000 acre-ft (about 3.7 x 109 L). Therefore, the degree of 
dilution is the ratio of the flux of contaminated groundwater to the representative volume of 
water defined by regulation. 
Supporting Reports: 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]). 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-61 November 2004 
6.2.24 Diffusion in the SZ (2.2.07.17.0A) 
FEP Description: Molecular diffusion processes may affect radionuclide transport in the 
SZ. 
Screening Decision: Included 
Screening Argument: N/A 
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). 
The effects of diffusion are particularly noticeable in a dual continuum media, such as that in 
effect in the Yucca Mountain volcanic units, where the majority of flow takes place in a limited 
number of fractures and minimal flow takes place in the rock matrix. Because the alluvium is 
not a dual continuum media, the effects of diffusion are minimal there. Thus, no credit is taken 
for diffusive transport in the alluvium. 
In the site-scale transport model diffusion is one of two components of a dispersion tensor. This 
tensor, denoted as D' (BSC 2004 [DIRS 170036], Section 6.4.2.1), is the sum of the mechanical 
dispersion tensor (D) for the flow system and the coefficient of molecular diffusion (D0) in 
porous media. Together, these processes are modeled using the stochastically sampled LDISP 
(BSC 2004 [DIRS 170042], 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 Site-Scale Saturated 
Zone Transport (BSC 2004 [DIRS 170036], Section 6.4.2.3). 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 [DIRS 156269], p. 581). The specific discharge value of 0.67 m/year 
reported in the Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036], Table 4-2) leads 
to fluid velocities on the order of 10-7 to 10-4 m/s. Combining this with the lower limit of the 
LDISP of 0.1 m given in Table 4-2 of Site-Scale Saturated Zone Transport (BSC 2004 
[DIRS 170036]), 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 2004 
[DIRS 170036]) is 5x10-10 m2/s. Thus, the effects of molecular diffusion, which are included in 
the SZ flow and transport models (BSC 2004 [DIRS 170042] Section 6.5.2.6) are overshadowed 
by advection and dispersion. Colloid transport, as described in Saturated Zone Colloid 
Transport (BSC 2004 [DIRS 170006]), is also subject to diffusion but is also dominated by 
advection and hydrodynamic dispersion. Matrix diffusion (which contributes to retardation) is 
addressed in the FEP 2.2.08.08.0AMatrix diffusion in the SZ. 
Supporting Reports: 
 Saturated Zone Colloid Transport (BSC 2004 [DIRS 170006]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-62 November 2004 
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. 
Screening Decision: Included 
Screening Argument: N/A 
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, 
affect the sorption coefficient, Kd, and thus, the retardation factor, Rf, for each radionuclide. In 
the Site-Scale Saturated Zone Transport model (BSC 2004 [DIRS 170036], Appendices A 
and C), these coefficients are entered directly in the transport base-case model that describes 
radionuclide transport via the distribution coefficients and the retardation factors (BSC 2004 
[DIRS 170036], Section 6.4.2.4, Equations 56 (a, b) and 57), which describe reactive transport 
through porous media. Appropriate ranges and distributions of values for Kds (BSC 2004 
[DIRS 170036], Appendix A) are chosen based on expert elicitation (CRWMS M&O 1998 
[DIRS 100353], Section 3.2), and laboratory and field studies for the sorption coefficient Kd 
(BSC 2004 [DIRS 170036], Appendix A). These ranges implicitly include variations in the 
chemical characteristics of SZ waters. Of particular interest, partitioning coefficients are 
bounded by the assumption that SZ groundwaters are oxidizing (BSC 2004 [DIRS 170036], 
Section 6.3, Items 4 and 7). These parameter ranges are incorporated in the model abstraction 
through the Kd variables KDNPVO (neptunium sorption coefficient in volcanic units), KDRAVO 
(radium sorption coefficient in volcanic units), KDSRVO (strontium sorption coefficient in 
volcanic units), KDUVO (uranium sorption coefficient in volcanic units), KDNPAL (neptunium 
sorption coefficient in the alluvium), KDRAAL (radium sorption coefficient in the alluvium), 
KDSRAL (strontium sorption coefficient in the alluvium), KDUAL (uranium sorption 
coefficient in the alluvium), KD_AM_VO (americium sorption coefficient in the volcanic units), 
KD_CS_VO (cesium sorption coefficient in the volcanic units), KD_PU_VO (plutonium 
sorption coefficient in the volcanic units), KD_AM_AL (americium sorption coefficient in the 
alluvium), KD_CS_AL (cesium sorption coefficient in the alluvium), KD_PU_AL (plutonium 
sorption coefficient in the alluvium), and the equilibrium sorption between aqueous and solid 
phases and a colloidal phase for the radionuclides Am, Cs, Pa, Pu, and Th (BSC 2004 
[DIRS 170042], Section 6.5.2.12). The sampled parameters Kd_Pu_Col and Kd_Cs_Col model 
partitioning between the aqueous and colloidal phases for Pu and Cs, respectively. The colloid 
retardation factor in the alluvium and the volcanic units are modeled through the sampled 
parameters, the colloid retardation factor in the alluvium (CORAL), and CORVO (the colloid 
retardation factor in volcanic units) (BSC 2004 [DIRS 170042], Sections 6.5.2.8 and 6.5.2.11). 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-63 November 2004 
Regarding the spatial and temporal dependencies of Kd, geochemical analysis indicates that 
current SZ groundwater under the repository and along the SZ transport path is oxidized 
paleoclimate recharge water (BSC 2004 [DIRS 170037], Appendix A, Section A7.1.2). Spatial 
variability in the composition of the groundwater reflects, in part, temporal variability in 
recharge when data from the Fortymile Wash are included. Uncorrected 14C groundwater ages 
range from a few thousand years in the vicinity of the Fortymile Wash to values greater than 
15,000 years under portions of Yucca Mountain (BSC 2004 [DIRS 170037], Appendix A, 
Section A.6.6.6.6.2 and Table A6-9). 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 between wells J-13 and 
UE-25p#1 in the model area brackets the temporal variations expected to occur in the water 
composition (BSC 2004 [DIRS 170036], Appendix A, Section A-3). Additionally, 
approximately a 120 m rise in the water table within the repository vicinity is taken as a 
reasonable upper bound for UZ transport simulations under glacial-transition climatic conditions 
(BSC 2004 [DIRS 170037], Section 6.4.5.1), corresponding to paleoclimatic conditions. 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 ranges 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. 
Supporting Reports: 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037], Appendix) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]). 
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 
radionuclides. 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. 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
Geochemical analysis indicates current SZ groundwater under the repository and along the SZ 
transport path is paleoclimate recharge water (BSC 2004 [DIRS 170037], Appendix A, 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-64 November 2004 
Section A7.1.2). These waters represent a mixture of waters from past flow systems having 
different climatic signatures than those indicative of current dry climatic conditions. These 
waters are reflective of cooler climatic conditions and cooler recharge waters 10,00016,000 
years ago (BSC 2004 [DIRS 170037], Appendix A, Section A-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 sorption 
coefficient (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 (BSC 2004 [DIRS 170036], Appendix A, 
Section A-3). Specific details pertaining to variability in Eh are discussed below. 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. 
For the TSPA-LA transport model (BSC 2004 [DIRS 170036], Section 6.3 and Appendix F), it is 
assumed that the groundwaters along the transport path are oxidizing from the UZ/SZ water table 
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, or will 
they increase in size. A large-scale change in oxidation state from that measured currently at 
Yucca Mountain is excluded on low consequence 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 [DIRS 100783], Section IV) and USW WT-17 (BSC 2004 
[DIRS 170036], Appendix F, Section F2.2). The reducing agents for groundwater in 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-65 November 2004 
these wells could be located in the groundwater itself or in the rock matrix. Because 
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 
[DIRS 103200]). Predicted radionuclide flow paths are focused primarily in the Prow 
Pass and Bullfrog units (BSC 2004 [DIRS 170037], Section 6.6.2.3). 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, indicates Eh 
measurements from this well may not be reflective of the rocks in situ redox 
conditions. The chemistry of groundwater pumped from borehole USW WT-17 in 
1998 was unique from other wells in the area. Groundwater from this well shows 
reducing characteristics (Eh less than 0.0 mV), little or no dissolved oxygen and 
nitrate, and high organic carbon (DTN: GS980908312322.008 [DIRS 145412], up to 
20 mg/L). 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 
downgradient 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 [DIRS 107425], p. 7-11) and no hydrocarbon activity. Because 
regulations dictate present socio-economic practices are reflective of future practices 
(10 CFR 63.305 (b) [DIRS 156605]), hydrocarbon exploration that could potentially 
produce a large reduction zone is 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 10,00016,000 years old 
(BSC 2004 [DIRS 170037], Appendix A, Section A6.6.6.6.2). 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 

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ANL-NBS-MD-000002 REV 03 6-66 November 2004 
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 
credible. 
5. There is no current mechanism known to support that reducing conditions will be more 
extensive along the flow path than what is currently measured. 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 
reducing 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 reducing 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 reducing zones is not likely to occur within the next 10,000 
years. 
Detailed discussions pertaining to related FEPs in groundwater chemistry as they affect 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: Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037], 
Appendix A, Section A-6.7); Saturated Zone Colloid Transport (BSC 2004 [DIRS 170006]); and 
Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036], Appendices A, B, C, and D). 
All of the above reasoned arguments support the conclusion that geochemical interactions and 
evolution is excluded based on low consequence to radiation exposure to the RMEI. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: Included 
Screening Argument: N/A 
TSPA Disposition: 
Complexing agents are included in the TSPA-LA (BSC 2004 [DIRS 170036], Appendix A). In 
the SZ inorganic complexing agents, such as carbonates, are dominant, whereas organic 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-67 November 2004 
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 (radionuclide 
sorption coefficients on the rock surfaces) and Kc (radionuclide sorption coefficients on colloids) 
enter via Equations 56 (a), 56 (b), 57, 76, 77, and 78 in Site-Scale Saturated Zone Transport 
(BSC 2004 [DIRS 170036], Sections 6.4.2.4.1), 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 Site-Scale Saturated Zone Transport (BSC 2004 
[DIRS 170036], Appendices A and B, respectively) and incorporated in the Saturated Zone Flow 
and Transport Model Abstraction (BSC 2004 [DIRS 170042], Sections 6.5.2.8, 6.5.2.11 and 
6.5.2.12 and Table 6-8). Available data are summarized in Site-Scale Saturated Zone Transport 
(BSC 2004 [DIRS 170036], Appendices B, C and D) . The parameter distributions for Kd and Kc 
are developed on the basis of these data. 
Supporting Reports: 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]). 
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. 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
The Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) does 
not implement a solubility limit for each transported radionuclide (similar to the UZ and the EBS 
regions). Solubility limits are imposed at the source term in the TSPA (BSC 2004 
[DIRS 169425], Section 6). This implementation allows 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 2004 [DIRS 169425]), 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 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-68 November 2004 
a solid phase onto mineral surfaces (due to precipitation, not adsorption) can reduce 
permeability, increase tortuosity, and clog pores, thus increasing transport times. 
Potential precipitation of a radionuclide due to solubility limits in the SZ would increase the 
transport time of that radionuclide in the SZ relative to the approach assuming no precipitation. 
Longer transport times in the SZ allow radioactive decay to diminish the mass of radionuclides 
that are ultimately released to the accessible environment. Consequently, the process of 
precipitation due to solubility limits would enhance the performance of the SZ with regard to its 
capability as a barrier to radionuclide migration. 
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. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: Included 
Screening Argument: N/A 
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 6.4.2.4.1 of Site-Scale Saturated Zone Transport (BSC 2004 
[DIRS 170036]), and in the numerical implementation of the model FEHM through the use of 
the diffusion coefficient and the random-walk particle-tracking method with a semi-analytical 
solution. Colloids undergo retardation in fractured volcanic rocks (BSC 2004 [DIRS 170006]) 
but are not subject to matrix diffusion in the simulations of colloid-factilitated radionuclide 
transport (BSC 2004 [DIRS 170036]). Diffusion into the matrix occurs from a subset of all 
fractures in the fractured volcanic units (i.e., flowing intervals), as described in Probability 
Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]). 
Matrix diffusion is included in the SZ transport model abstraction (BSC 2004 [DIRS 170042], 
Section 6.3 and Table 6-8) through the matrix diffusion parameter diffusion coefficient in 
volcanics (DCVO) , and is sensitive to the range of sampled parameters for flowing interval 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-69 November 2004 
spacing and porosity in the volcanic units (BSC 2004 [DIRS 170042], Sections 6.5.2.4 and 
6.5.2.5). 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 2004 
[DIRS 170042], Section 6.5.2.6). The cumulative distribution function 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 cumulative distribution function. 
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 (BSC 2004 [DIRS 170010], 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 volcanic units or the alluvium, because the effects would 
be small and would only retard transport. 
Supporting Reports: 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Saturated Zone Colloid Transport (BSC 2004 [DIRS 170006]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]). 
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. 
Screening Decision: Included 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-70 November 2004 
Screening Argument: N/A 
TSPA Disposition: 
Sorption of radionuclides onto rock surfaces can occur both in the volcanic rocks and the 
alluvium (BSC 2004 [DIRS 170036], Appendix A). This process is modeled through a suite of 
partitioning coefficients, Kds (BSC 2004 [DIRS 170042], Section 6.5.2.8) for the radionuclides 
Am, Cs, Np, Pa, Pu, Ra, Sr, Th, and U (BSC 2004 [DIRS 170036], Section 6.3 (Item 4 and 7), 
6.4.2.4, 6.4.2.5 and Appendix A, Sections A8 and A.9). The process of sorption during transport 
in fractured volcanic units has been confirmed at the field scale by tracer testing at the C-wells 
complex (BSC 2004 [DIRS 170010], Section 6.3). 
For many radionuclides the sorption kinetic time frame is relatively slow compared to the solute 
flow rates adjacent to the sorbing sites. That is, the exposure times of solute passing the sorbing 
sites is fast relative to the time it takes for the dissolved mass to sorb to the potential sorption 
sites. Additionally, the affinity of solute to sorb to a solid (the sorbing site) is dependent on the 
mineral composition and the shape of the solid. In the SZ flow and transport domain, the 
uncertainty in sorption kinetics is implemented by biasing sorption kinetics downward. 
Effectively, the model adopts partitioning coefficients based on the low points of the 
laboratory-derived sorption isotherms. This approach underestimates the range, median, and 
mean partitioning coefficient values used for the nine radionuclide classes modeled in the SZ 
(BSC 2004 [DIRS 170036], Appendices A and D). 
In the volcanic rocks, sorption in the matrix is explicitly included in the retardation coefficient Rf 
in Equations 56b and 57 of Site-Scale Saturated Zone Transport, (BSC 2004 [DIRS 170036], 
Section 6.4.2.4.1). Sorption within individual fractures is not included in the conceptual model; 
however, sorption can occur within flowing zones due to the rubblized matrix. This effect is 
included in the retardation coefficient R in Equation 56a in Section 6.4.2.4.1 of the site-scale SZ 
transport report; sorption in the alluvium is described in Equation 77 of that report. 
Radionuclides modeled as entrained irreversible colloids in Waste Form and In-Drift 
Colloids-Associated Radionuclide Concentrations: Abstraction and Summary (BSC 2004 
[DIRS 170025], Sectionand 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 2004 [DIRS 170036], Appendix A, Section A2). 
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 2004 [DIRS 170036], Appendix A, Section A8) and are reflected as 
such in alluvium Kd distributions. Table A-4 in Site-Scale Saturated Zone Transport (BSC 2004 
[DIRS 170036]) summarizes SZ sorption model parameters. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-71 November 2004 
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 2004 [DIRS 170042], Section 6.5.2.8 and Table 6-8); sorption for the same radionuclides 
in the alluvium is modeled through the parameters KDNPAL, KDRAAL, KDSRAL, and 
KDUAL (BSC 2004 [DIRS 170042], Section 6.5.2.8 and Table 6-8). 
Sorption of Reversible Colloids: Equilibrium sorption between aqueous and solid phases and a 
colloidal phase is modeled for nine radionuclide classes represented by partitioning of the 
radionuclides Am, Cs, Pa, Pu, and Th (BSC 2004 [DIRS 170036], Section 6.4.2.6 and 
Table 5-1). The sampled parameters Kd_Pu_Col and Kd_Cs_Col model partitioning of Pu and 
Cs 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 2004 [DIRS 170042], 
Section 6.5.2.12). 
Sorption of Irreversible Colloids: In the volcanic units, the dispersed advectively transported 
Pu and Am colloids (BSC 2004 [DIRS 170006], Section 6.4 and BSC 2004 [DIRS 170025], 
Section 6.3.3.2) sorb onto fracture surfaces through a colloid retardation factor CORVO 
(BSC 2004 [DIRS 170042], Section 6.5.2.11). In the alluvium, these same colloids are 
effectively sorbed via a sampled retardation factor CORAL (BSC 2004 [DIRS 170042], 
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 Sorption 
Radionuclide Partitioning Parameters Between 
Colloids and Parent Rock Radionuclide Partitioned 
Between Solution and Parent 
Rock (No colloid transport) 
Sorption Between Solution 
and Rock Surface 
Radionuclide 
Irreversibly Sorbed to 
Colloids 
RN 
Volcanic 
Units Alluvium 
Volcanic 
Units Alluvium 
Sorption 
Between 
Solution and 
colloids 
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 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-72 November 2004 
Table 6.2-2. Summary of the SZ Sampled Parameters Specific to Radionuclide Sorption (Continued) 
Radionuclide Partitioning Parameters Between 
Colloids and Parent Rock Radionuclide Partitioned 
Between Solution and Parent 
Rock (No colloid transport) 
Sorption Between Solution 
and Rock Surface 
Radionuclide 
Irreversibly Sorbed to 
Colloids 
RN 
Volcanic 
Units Alluvium 
Volcanic 
Units Alluvium 
Sorption 
Between 
Solution and 
colloids 
Volcanic 
Units Alluvium 
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 
Source: BSC 2004 [DIRS 170042], Sections 6.5.2.8, 6.5.2.11, 6.5.2.12. 
RN= radionuclide 
Supporting Reports: 
 Saturated Zone Colloid Transport (BSC 2004 [DIRS 170006]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]). 
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. 
Screening Decision: Included 
Screening Argument: N/A 
TSPA Disposition: 
The colloid-facilitated transport of radionuclides is explicitly included in the SZ transport 
abstraction model and the SZ one-dimensional transport model (BSC 2004 [DIRS 170042] 
Sections 6.5.2.11 and 6.5.2.12). Colloids are subject to advection in the alluvium and fractures 
of tuff units and are not assumed to diffuse into the fractured rock matrix (BSC 2004 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-73 November 2004 
[DIRS 170036], Section 6.4.2.6 and Appendix B). Colloid transport in the SZ has been 
investigated at the field scale by tracer testing using microspheres, as described in Saturated 
Zone In-Situ Testing (BSC 2004 [DIRS 170010], Section 6.3). 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 2004 [DIRS 170042], 
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 
(BSC 2004 [DIRS 170025], Section 6.3.1). Colloids with irreversibly attached radionuclides are 
subject to retardation in the SZ both in the fractured tuff and the alluvium. However, a small 
fraction of colloids with irreversibly attached radionuclides are transported through the SZ with 
no retardation due to the kinetic nature of colloid attachment to the aquifer materials (BSC 2004 
[DIRS 170006], Section 6.6) The parameter distributions related to reversible sorption onto 
colloids are based on field observations and laboratory experiments performed on colloids and 
geochemical conditions found in the Yucca Mountain vicinity (BSC 2004 [DIRS 170006], 
Section 7). These are labeled as Kd_Am_Col, Kd_Pu_Col, Kd_Cs_Col, and Conc_Col 
(groundwater concentration of colloids) in Saturated Zone Flow and Transport Model 
Abstraction (BSC 2004 [DIRS 170042], Table 4-3). The parameters related to the retardation of 
colloids with irreversibly attached radionuclides are CORVO and CORAL (BSC 2004 
[DIRS 170042], Table 6-8). 
Supporting Reports: 
 Saturated Zone Colloid Transport (BSC 2004 [DIRS 170006]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]). 
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. 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
Currently, groundwater discharge from the Yucca Mountain flow system occurs at Franklin Lake 
Playa (also known as Alkali Flat) and Ash Meadows (DAgnese et al. 1997 [DIRS 100131] 
pp. 40 to 48), both over 10 km beyond the 18-km accessible environment boundary and the 
reference biosphere (BSC 2004 [DIRS 169734], Figure 7-4). There is evidence of paleospring 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-74 November 2004 
discharge points within northern Amargosa Desert that could become reactivated during wetter 
climatic conditions. These are the paleospring deposits located in Crater Flat, Crater Flat Wash, 
Amargosa Valley Diatomite, Indian Pass, Stranton Well, Mesquite Wash and the Amargosa 
River Snail Site (Paces et. al 1997 [DIRS 109148]). The Stranton Wells, Mesquite Wash and 
Amargosa River Snail Site paleospring deposits lie at the far terminus of Fortymile Wash and 
downstream from the projected flow path (from the repository to the 18-km boundary). The 
other paleospring deposits are separated from Fortymile Wash by faults and ridges and are not 
along the projected transport path. Therefore, they would not contain contaminants originating 
from the repository if reactivated under wetter climatic conditions. 
Geochemical analysis indicates paleospring deposits along the far terminus of Fortymile Wash 
are not likely to be activated within the regulatory time frame. With the exception of the 
Amargosa River Snail Site, geochemical dating indicates the last episode of paleospring activity 
for the majority of paleosprings occurred between 1420 ka ago (Paces et. al 1997 
[DIRS 109148]). Stranton Wells was active 4060 ka, Mesquite Wash active 30 ka, and the 
Amargosa River Snail Site between 9 to 12 ka (Paces et. al 1997 [DIRS 109148]). There is some 
uncertainty regarding the 912 ka activity for the Amargosa River Snail Site. Surface lag 
samples taken from this site, and collected for dating, indicate plant petrifications may have 
tapped a subsided water source (a one-time discharge point that has been lowered below the 
ground surface). Thus surface discharge may have ceased much earlier than indicated from 
geochemical dating. Nevertheless, if the plume potentially discharges at those few reactivated 
discharge deposits located south of Fortymile Wash, it would be of a lower concentration than 
that at the 18-km boundary, simply because these locations are located several kilometers beyond 
the accessible environment boundary. Longer path lengths from the repository facilitate the 
processes of sorption and transverse dispersion; these two processes lower the plumes 
concentration levels as the path length increases. Additionally, a longer path length coupled with 
more sorption and dispersion equates to longer transport times, thus allowing more time for 
radioactive decay; more time for decay reduces the radionuclide concentrations in groundwater 
withdrawn from the community wells. 
Groundwater modeling results demonstrate any discharge to the land surface within the next 
10,000 years, if it occurs at all, would be expected to occur at least 4 km downstream of the 
18-km boundary. DAgnese et al.s (1999 [DIRS 120425]) Death Valley regional groundwater 
model investigated future spring locations given a full glacial climate scenario and a postglacial 
warming scenario. Results from the full glacial simulations show groundwater discharging at the 
land surface in Fortymile Wash located about 4 km downstream from the 18-km boundary. 
Under the postglacial warming scenario, these simulations resulted in land surface discharge 
occurring about 8 km beyond the 18-km boundary. The full glacial climate scenario assumes the 
wettest climate conditions within the 400,000 year climate cycle. For the 10,000 year regulatory 
period, climatic conditions will be in a glacial transition phase, which is not as wet or cool as the 
full glacial climate scenario. Therefore, predicted groundwater discharge using the full glacial 
climate scenario is considered unrealistic (too much recharge) within the 10,000 year time frame 
of interest (BSC 2004 [DIRS 169734], Section 6.5.3.5). 
Flow and transport modeling efforts were performed on the site-scale model domain to assess 
water table elevations reflective of glacial climatic conditions (BSC 2004 [DIRS 170036], 
Appendix E). For these simulations the water table was allowed to rise under the repository by 

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ANL-NBS-MD-000002 REV 03 6-75 November 2004 
as much as 100 m. Model results from these simulations do not manifest spring formation within 
the 18-km boundary but do show a shallow water table within 5 m of the surface. The shallow 
water table corresponds to the three paleospring deposits located along Highway 95 and at the 
southern end of Crater Flat (BSC 2004 [DIRS 170037], Figure 6-11). All are located within the 
fork of the Solitario Canyon Splay fault (BSC 2004 [DIRS 170037], Figure 6-4). Even if the 
water table were to rise another 5 m to form springs, the splay fault (BSC 2004 [DIRS 170037], 
Figure 6-4) serves as a barrier between Crater Flat and Fortymile Wash. It is in the Fortymile 
Wash where flow paths from the repository to the 18-km boundary converge. Consequently, if 
springs were to develop in the shallow water table area, radionuclides released from the 
repository will not likely be constituents of the spring waters. 
In summary, current natural groundwater discharge points along the SZ flow paths are several 
kilometers downstream from the 18-km boundary. Future discharge points, if they occur at all, 
will be located several kilometers downstream from the 18-km boundary. Radionuclide 
concentrations at natural discharge locations would be less than concentrations at the 18-km 
boundary due to increased dispersion and sorption. Thus, future potential natural discharge 
points in the accessible environment will implicitly have a lower concentration than groundwater 
that crosses the 18-km boundary. Natural groundwater discharged to the surface several 
kilometers downstream from the reference biosphere will have more lateral dispersion, sorption, 
and a longer time for radioactive decay, thus a lower concentration than groundwater withdrawn 
from the community wells. 
The biosphere model for the groundwater exposure scenario includes all exposure pathways 
expected to contribute to the annual dose to the RMEI, as required by 10 CFR 63.311 
(DIRS 156605). Exposure is calculated for the radionuclide concentration in groundwater at the 
boundary of the accessible environment. As noted above, this concentration would be greater 
than that for the predicted discharge points along the groundwater flow path from Yucca 
Mountain, downstream from the compliance point. The potential pathways from exposure to 
water flowing from reactivated springs or other groundwater discharge points are 
(1) consumption of water, (2) external exposure from contaminated soil around springs, and 
(3) water immersion. These pathways are included in the biosphere model because groundwater 
entering the biosphere from a spring or other discharge point would be used in the same way as 
groundwater from a well. Moreover, the consequences of exposure arising from a spring would 
be negligible compared to the exposure received from the pathways included in the biosphere 
model. For example, consumption of water from a spring by the RMEI would not affect the 
calculated dose because exposure from drinking water is modeled using the radionuclide 
concentration at the compliance point and a fixed water consumption rate, as required by 
10 CFR 63.312 (c). External exposure from water was excluded from the biosphere model 
because immersion in water from a spring or well would have an insignificant contribution to the 
dose (BSC 2004 [DIRS 169460], Section 7.4.8.2). External exposure from the soil around 
springs would not exceed external exposure calculated in the biosphere model because the 
average exposure time at springs for the population would be low and the external exposure in 
that model is calculated for cultivated soil continuously irrigated with contaminated water. The 
concentration of radionuclides in irrigated soil would be higher than in soil around springs at the 
predicted discharge points along the groundwater flow path from Yucca Mountain. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-76 November 2004 
In conclusion, it is not necessary to specifically address the potential consequences of exposure 
to water discharged to the surface within the reference biosphere because such exposure would 
be insignificant and is bounded by the dose calculated using the biosphere model. As a result, 
this FEP has no adverse effects on performance and is excluded based on low consequence. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: ExcludedLow consequence 
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 percent liquid saturated, thus favoring vapor exchange and microbial growth, resulting 
in the UZ including this FEP (BSC 2004 [DIRS 170012], Section 6.2.33). However in the SZ 
evidence of microbial activity is minimal, which is supported by geochemical analysis of 
groundwater samples taken from SZ wells within the Yucca Mountain vicinity 
(DTN: GS931100121347.007 [DIRS 149611]; DTN: GS010308312322.003 [DIRS 154734]). 
Results from the above analysis found little to no organic carbon in these waters. 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 (BSC 2004 [DIRS 170037], Appendix A, Section A7.1.2), reflective of 
cooler climatic conditions and cooler recharge waters (BSC 2004 [DIRS 170037], Appendix A, 
Section A6.6.6.6.2). Paleoclimate recharge waters have higher carbonate concentrations, which are 
components of inorganic complexing agents and higher concentrations of dissolved CO2 gas 
(BSC 2004 [DIRS 170037], Section 6.7.5.3). 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 and Site-Scale Saturated Zone Transpor, (BSC 2004 [DIRS 170036], 
Appendix A, Section A4). 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. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-77 November 2004 
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 (BSC 2004 [DIRS 170042], 
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 radiation exposure to the RMEI or radionuclide releases to the accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
Development of thermal convection cells in porous media is classically driven by an underlying 
heat source. In the case of the SZ at Yucca Mountain the repository heat source is located above 
the SZ, in the UZ. Elevated temperatures at the water table resulting from repository heat would 
lead to lateral density gradients in groundwater and could induce some lateral groundwater 
movement. These effects would lead primarily to greater transverse mixing and dispersion in the 
SZ below the repository. Enhanced dispersive mixing in the SZ would lead to greater dilution of 
radionuclide concentrations and would be of low consequence with regard to radionuclide 
release rates to the accessible environment. 
Thermal effects will have more of an impact on flow in the near-field than in the SZ. In 
Features, Events, and Processes in UZ Flow and Transport (BSC 2004 [DIRS 170012], 
Section 6.9.9), 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 UZ (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 
radiation exposure to the RMEI or radionuclide releases to the accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-78 November 2004 
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 saturated zones. 
Screening Decision: Included 
Screening Argument: N/A 
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 Saturated Zone Site-Scale Flow 
Model (BSC 2004 [DIRS 170037]) using a conservation of fluid-rock energy equation in the 
numerical code FEHM. The fluid-rock energy equation is, in part, a function of permeability, 
density, viscosity, and temperature (BSC 2004 [DIRS 170037], Section 6.5.3.7). For 
temperatures that range between 20C to 100C, 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 Saturated Zone 
Site-Scale Flow Model (BSC 2004 [DIRS 170037], Section 6.5.3.7) assigns a specified 
temperature to each node, which varies with depth and is based on variable temperature 
measurements reported by Sass et al. (1988 [DIRS 100644]), using an average geothermal 
gradient. Temporal variations in the natural geothermal gradient are expected to be minor, as 
explained with regard to hydrothermal activity. Specifically, studies of two-phase fluid 
inclusions in the UZ at Yucca Mountain using petrography, microthermometry, and U-Pb dating 
indicate that temperatures have remained close to the current ambient values over the past 
2 million5 million years (Wilson et al. 2003 [DIRS 163589], Section 8). These findings show 
that significant or widespread alteration of the geothermal gradient has not occurred in the UZ in 
the recent geologic past, and suggest that such variations have been absent from the nearby SZ. 
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 2004 [DIRS 170037], 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. The site-scale SZ transport 
model (BSC 2004 [DIRS 170036]) incorporates these effects by using the calibrated SZ site-scale 
flow model as its basis. Furthermore, the uncertainty that temperature may have on matrix 
diffusion is implicitly captured in the range for effective diffusion coefficients adopted in the SZ 
flow and transport model (BSC 2004 [DIRS 170042], Section 6.5.2.6). 
Additionally, numerical simulations coupling heat transport and flow processes were performed 
using, as input, SZ temperature values in the SZ (BSC 2004 [DIRS 170037], Section 7.2.4). The 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-79 November 2004 
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. 
Supporting Reports: 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]). 
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 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. 
Screening Decision: ExcludedLow consequence 
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 2004 [DIRS 169866], 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 2004 [DIRS 169866], 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 2004 [DIRS 169866], Sections 6.5.10 and 6.5.11). 
Compressive stresses transition to tensile stresses at approximately 180 m above the repository 
(BSC 2004 [DIRS 169866], Section 6.5.11). 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 subvertical fractures are affected most by compressive stresses, with many fractures 
closing to their residual fracture aperture widths. Horizontal fracture apertures are least affected 
by thermally induced mechanical stresses; under compressive stresses they tend to open slightly. 
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 2004 
[DIRS 169866], 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 2004 [DIRS 169866], Figures 6.5.12-1, 6.5.12-2, and 6.5.12-3). 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-80 November 2004 
There are few to no changes in the permeabilities of both vertical and horizontal fractures located 
approximately 150 m below the repository. However, if a compressional pulse were to affect SZ 
fractures at the water table, it would most likely affect vertical to subvertical fractures since it is 
the vertical to subvertical fractures that are most sensitive to compressional stresses. Below the 
repository SZ flow primarily takes place in the fractures of the volcanic units. Therefore a 
reduction in permeability of vertical to subvertical fractures will promote flow in the surrounding 
less permeable rock matrix and thus increase groundwater transport times. 
At 10,000 years, when the repository is well into a cooling phase, thermal-mechanical stresses do 
not impart significant changes in vertical and horizontal fractures beyond 50 m below the 
repository (BSC 2004 [DIRS 169866], Figure 6.5.12-2). Because the top of the SZ is 
approximately 335 m below the repository (DTN: GS000808312312.007 [DIRS 155270], 
Table S00397 001; CRWMS M&O 2000 [DIRS 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 report Features, Events, and Processes in UZ Flow and Transport (BSC 2004 
[DIRS 170012], Section 6.9.12), it is concluded that thermally induced stresses would have no 
long-term effect on rock and fracture properties above and below the repository that would affect 
long-term UZ flow and transport. Specifically, thermally induced stresses would tend to reduce 
UZ fracture permeabilities and effectively reduce UZ transport times below the repository. 
Consequently, this FEP was excluded in the UZ based on low consequence. Because 
thermal-mechanical stresses are excluded in the UZ near-field, by deduction, the 
thermal-mechanical stress pulse will have less of an impact further out in the region of the SZ. 
To summarize, thermal-mechanical stresses cause few 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 decrease with distance and 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 effect on SZ fractures. In conclusion, thermal-mechanical 
stresses imposed on fractures within the vicinity of the repository have little to no effect on SZ 
fractures properties. Thermal-mechanical stresses on fractures in the SZ are excluded based on 
low consequence because they will not significantly change radiation exposure to the RMEI or 
radionuclide releases to the accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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 to the stress field that may change the properties 
(both hydrologic and mechanical) in and along faults. Cooling following 
the peak thermal period will also change the stress field, further affecting 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-81 November 2004 
fault properties near the repository. 
Screening Decision: ExcludedLow consequence 
Screening Argument: 
For purposes of assessing the thermal-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 2004 [DIRS 169866], 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 2004 [DIRS 169866], Section 6.5.11). Moving away from the repository, stresses dampen. 
Above the repository, thermally induced stresses are both compressive and tensile in nature 
(BSC 2004 [DIRS 169866], 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 subvertical 
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), are 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 its size and distance from the heat source. If thermally induced 
mechanical stresses will not affect fracture hydrologic properties in the SZ, 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 (BSC 2004 [DIRS 170012], Section 6.9.11). Because thermal-mechanical 
stresses are excluded in the UZ, by deduction, the thermal-mechanical stress pulse will have 
less of an impact further out in the region of the SZ, so it is also excluded in the SZ. 
In summary, thermal-mechanical stresses from waste emplacement imposed on faults located in 
the SZ are excluded due to low consequence, because they will not significantly change radiation 
exposure to the RMEI or radionuclide releases to the accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-82 November 2004 
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 may produce tension 
fracturing in the Paintbrush non-welded tuff and other units above the 
repository. These fractures may 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 may affect flow and radionuclide transport to the saturated 
zone. 
Screening Decision: ExcludedLow consequence 
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 2004 [DIRS 169866], 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 2004 
[DIRS 169866], Section 6.5.11). The compressional stress pulse loses strength as it moves 
outward from the repository. Because 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 2004 
[DIRS 169866], Section 6.5.12). Below the repository, compressive stresses primarily affect 
vertical to subvertical fractures and their permeabilities, in a region that extends approximately 
100150 m directly below the repository (BSC 2004 [DIRS 169866], Figure 6.5.12-3). At the 
water table thermal-mechanical stresses are not enough to produce a compressional stress that 
would significantly affect fracture permeability in the SZ (see FEP 2.2.10.04.0A 
Thermo-mechanical stresses alter characteristics of fractures near repository). Since fractures are 
more susceptible to thermally induced stresses than the rock matrix 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 2.2.10.04.0A-Thermo-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. Thermal-mechanical stresses on the UZ rock 
properties are excluded in the UZ (BSC 2004 [DIRS 170012], Section 6.9.12). By deduction, 
thermal-mechanical stresses will have less of an effect in the far-field and should be excluded as 
well. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-83 November 2004 
Thermal-mechanical stress 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 2004 [DIRS 170012], 
Section 6.9.12). 
In summary, thermal-mechanical stresses on the SZ rock properties are excluded due to low 
consequence, because they will not significantly change radiation exposure to the RMEI or 
radionuclide releases to the accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: ExcludedLow consequence 
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 2004 [DIRS 169866], 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 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-84 November 2004 
(BSC 2004 [DIRS 169866], 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 32C to 34C 
(BSC 2004 [DIRS 169866], Section 6.3.1; Figures 6.3.1-6 and 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 2004 [DIRS 169866], Figures 6.4-12 and 6.4-16). Concurrently, no significant 
precipitation or dissolution of calcite-bearing minerals in fracture fillings is seen (BSC 2004 
[DIRS 169866], Section 6.4.3.3.3; Figure 6.4-18). If there is no significant precipitation or 
dissolution of calcite in fracture fillings just above the water table due to thermal loading, there 
will be no significant precipitation or dissolution of calcite along the SZ transport path due to 
thermal effects.. 
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 by noticeable precipitation or 
dissolution minerals such as calcite in fracture fillings (BSC 2004 [DIRS 169866], 
Section 6.4.3.3.1, Figures 6.4-13 and 6.4-14; and Section 6.4.3.3.2, Figures 6.4-16 and 6.4-17). 
Temperatures at or above 50C facilitate mineral-water reactions, causing vitric and 
silica-bearing minerals to degrade to zeolites and other secondary minerals, including clays. 
Zeolites tend to have the highest porosity and sorption capacity of all the secondary minerals 
found at Yucca Mountain. 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 silica-bearing minerals in the 
SZ. This is corroborated with modeling results reported in Mountain-Scale Coupled Processes 
(TH/THC/THM) Models (BSC 2004 [DIRS 169866]); alteration of silicate minerals decreases 
with distance from the repository. Minimal-to-no mineral alteration is seen just above the water 
table (BSC 2004 [DIRS 169866], Section 6.4.3.3; Figures 6.4-20 through 6.4-24). 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 (BSC 2004 [DIRS 170036], Table 6.6-1b). 
Consequently, any possible alteration of zeolites in the SZ will not affect the SZ barrier 
capability. 
The SZ Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) does not implement 
a solubility limit for each transported radionuclide. The radionuclide concentration that is 
introduced into the SZ from the UZ is unconstrained. Furthermore, radionuclides introduced in 
the UZ from the EBS are also unconstrained; that is, the solubility is not reduced as 
radionuclides go from the higher temperature repository conditions to the UZ. Therefore, SZ 
temperature variability on radionuclide solubility will have no effect on radionuclide transport in 
the SZ. 
In the report Features, Events, and Processes in UZ Flow and Transport (BSC 2004 
[DIRS 170012], Section 6.9.14), thermal-chemical effects on dissolution and precipitation in the 
Calico Hills unit are evaluated. That analysis indicates thermal-chemical effects are limited to 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-85 November 2004 
the near-field environment and are of short duration, which will not have a significant effect on 
UZ contaminant transport or the release to the accessible environment. Because 
thermal-chemical effects are excluded in the near-field, by deduction, the thermal-chemical 
alteration will have less of an impact further out in the region of the SZ and are also excluded 
there. All of these reasons support excluding this FEP due to low consequence, because it will 
not significantly change radiation exposure to the RMEI or radionuclide releases to the 
accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: ExcludedLow consequence 
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 2004 [DIRS 169866], 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 2004 [DIRS 169866], 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 32C to 34C (BSC 2004 [DIRS 169866], Section 6.3.1 and 
Figures 6.3.1 6, 6.3.1-7). These elevated temperatures are, at most, only 0C4C above ambient 
water table temperatures beneath the repository. The model indicates that elevated temperatures 
decrease to within 1C2C 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 30C and 34C (Fridrich et al. 1994 [DIRS 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 40C45C in units where transport takes place (measured in well UE-25p#1, Site-Scale 
Saturated Zone Flow Model, BSC 2004 [DIRS 170037], Table 7-9), 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 by noticeable precipitation or dissolution minerals 
such as calcite in fracture fillings (BSC 2004 [DIRS 169866], Sections 6.4.3.3.1, 6.4.3.3.2, 
6.4.3.3.2 and Figures 6.4-13, 6.4-14, 6.4-16, 6.4-17, and 6.4-18). If a thermal pulse emanating 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-86 November 2004 
from the repository does not significantly increase pH and CO2 concentrations at the water table, 
there will not be a significant increase of these two components in the SZ flow domain farther 
away from the heat source. 
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. In the SZ models, 
radionuclide partitioning coefficients are based on ambient SZ temperatures and are not 
temperature-dependent. An increase in sorption capacity due to an increase in SZ water 
temperatures would tend to increase SZ transport times. Thus, including the effects of elevated 
SZ groundwater temperatures would not have an adverse effect on performance. 
Radionuclide-bearing waters at elevated temperatures would be less dense than ambient waters. 
Density and temperatures gradients, together, would promote lateral dispersion along the 
transport path. Lateral dispersion would facilitate matrix diffusion (i.e., physical retardation) as 
the plume extends laterally along a wider transport path, reducing transport times and 
radionuclide peak concentrations. The combination of the above conditions in the SZ transport 
model would both increase transport times and reduce peak concentrations, thus reducing peak 
exposure to the RMEI. Therefore, temperature-induced density effects would not have an 
adverse effect on performance. Repository-induced thermal effects on SZ mechanical properties 
are discussed in FEP 2.2.10.05.0A - Thermo-Mechanical Stresses Alter Characteristics of Rocks 
Above and Below the Repository. 
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 radiation 
exposure to the RMEI or radionuclide releases to the accessible environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: ExcludedLow consequence 
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 [DIRS 107425], p. 5). While the geologic elements required for 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-87 November 2004 
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 [DIRS 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 SZ flow and transport model. As a result, 
gas-generating processes 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 (Kvenvolden 1998 
[DIRS 166162], pp. 9 to 11). Clathrates are not a potential hydrocarbon source in the Yucca 
Mountain vicinity since low-temperature, high-pressure conditions do not exist in the region. 
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 [DIRS 149611]; 
DTN: GS010308312322.003 [DIRS 154734]; DTN: GS011108312322.006 [DIRS 162911]). 
Organic carbon is a biproduct of microbial activity. 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. 
Because the repository is situated in the UZ approximately 335 m above the water table 
(DTN: GS000808312312.007 [DIRS 155270], Table S00397 001; CRWMS M&O 2000 
[DIRS 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 2004 [DIRS 170012], Section 6.7.2). 
In summary, the potential effects of naturally occurring gases in the geosphere can be excluded 
from the SZ flow and transport model based on low consequence, because they will not 
significantly change radiation exposure to the RMEI or radionuclide releases to the accessible 
environment. 
TSPA Disposition: N/A 
Supporting Reports: N/A 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-88 November 2004 
6.2.42 Undetected Features in the SZ (2.2.12.00.0B) 
FEP Description: Undetected features in the SZ portion of the geosphere 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. 
Screening Decision: Included 
Screening Argument: N/A 
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 one-dimensional transport model 
through parameter distributions (BSC 2004 [DIRS 170042]); both models are described in the 
report by BSC (2004 [DIRS 170042], 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. 
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, one 
implicitly incorporates undetected features into the model (BSC 2004 [DIRS 170037], 
Section 6.6.1). The site-scale SZ transport model (BSC 2004 [DIRS 170036]) incorporates these 
effects by using the calibrated SZ site-scale flow model as its basis. 
Groundwater specific discharge 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 
volcanic units these could be undetected faults and fractures or fracture clusters. Uncertainty in 
parameters related to these features are applied to the hydrogeologic units defined in the 
hydrogeologic framework model documented in Hydrogeologic Framework Model for the 
Saturated Zone Site Scale Flow and Transport Model (BSC 2004 [DIRS 170008]). Uncertainty 
in groundwater specific discharge in the SZ is based on data gathered from single- and multiwell 
hydrologic testing in the volcanic units near Yucca Mountain and field testing in the alluvium at 
the alluvial tracer complex. In the TSPA, the GWSPD parameter is a multiplication factor 
applied to all SZ permeability values and specified boundary fluxes (BSC 2004 [DIRS 170042], 
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. Uncertainty in the 
flowing interval spacing parameter (BSC 2004 [DIRS 170014]) implicitly accounts for 
smaller-scale undetected features that transmit significant quantities of groundwater in the SZ. 
The assessment of horizontal anisotropy in permeability, as documented in Saturated Zone 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-89 November 2004 
In-Situ Testing (BSC 2004 [DIRS 170010]), potentially includes the effects of preferentially 
oriented undetected features on groundwater flow in the SZ. 
The key parameters that implicitly model undetected features (BSC 2004 [DIRS 170042]) are 
(1) GWSPD, (2) HAVO, (3) FISVO, (4) LDISP, and (5) sorption coefficients (Kd) for 9 the 
classes of radionuclides modeled in both the alluvium and volcanic units (parameters are 
described in Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042], 
Sections 6.5.2.1, 6.5.2.9, 6.5.2.10, 6.5.2.4, and 6.5.2.8 and Table 6-8). 
Additional parameters that model undetected SZ features are FPVO, LDISP incorporated in both 
the volcanic units and the alluvium, effective porosity in the alluvium units 7 and 19 (NV7 and 
NV19), and alluvium bulk density (bulk density). Additionally, in the SZ transport abstraction 
model (BSC 2004 [DIRS 170042], 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 alluvium uncertainty zone are defined with the sampled parameters FPLAW 
and FPLAN . The above parameters that implicitly model undetected features are described in 
Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042], 
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). 
Supporting Reports: 
 Hydrogeologic Framework Model for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170008]) 
 Probability Distribution for Flowing Interval Spacing (BSC 2004 [DIRS 170014]) 
 Saturated Zone Site-Scale Flow Model (BSC 2004 [DIRS 170037]) 
 Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]) 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]) 
 Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010]). 
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. 
Screening Decision: Excludedby regulation 
Screening Argument: 
The reference biosphere is defined as the description of the environment inhabited by the RMEI 
(10 CFR 63.2 [DIRS 156605]). FEPs that describe the reference biosphere are those that affect 
the RMEI. Conversely, FEPs that occur outside the reference biosphere do not affect the 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-90 November 2004 
RMEIs exposure and are not included. The postclosure individual protection standard is 
formulated in terms of annual doses to the RMEI (10 CFR 63.311(b)). Because the performance 
assessment uses the characteristics of the reference biosphere to demonstrate compliance with 
the individual protection standard (66 FR 55732 [DIRS 156671], p. 55784) the FEPs related to 
any processes occurring outside the reference biosphere are implicitly excluded. Therefore, 
groundwater discharge to surface outside the reference biosphere is excluded on the basis of 
inconsistency with the requirements for demonstration of compliance with the postclosure 
performance objectives (10 CFR 63.113(b)). 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: Included 
Screening Argument: N/A 
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 (both models are described in SZ Flow and Transport Model Abstraction 
BSC 2004 [DIRS 170042], 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 radioactive decay products, resulting in a boosting 
of the initial inventory of some radioactive decay products (BSC 2004 [DIRS 170042], 
Section 6.3.1). This approach is a conservative simplification that overestimates the mass of 
these radioactive decay products 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 one-dimensional transport model (BSC 2004 [DIRS 170042], 
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 
radioactive decay products. Consequently, the simplified approach of decay product source 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-91 November 2004 
boosting is used for some direct radioactive decay products, and the SZ one-dimensional 
transport model is used for the longer decay chains. 
Supporting Reports: 
 Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042]). 
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. 
Screening Decision: ExcludedLow consequence 
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 (84Sr, 
86Sr, 87Sr, 88Sr), uranium (234U and 238U), and carbon (12C and 13C) (BSC 2004 [DIRS 170037], 
Appendix A, A6.3.1.2)). In the SZ flow and transport 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. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
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. 
Screening Decision: Excludedby regulation 
Screening Argument: 
The applicable regulations do not require consideration of the irrigation-recycling process in 
calculating the dose to the RMEI under 10 CFR 63.311 (DIRS 156605). See Ziegler (2004 
[DIRS 172234]) for a complete discussion of the regulatory screening argument for this FEP. 
The SZ FEPs relate to natural conditions and do not include human-induced changes to 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-92 November 2004 
radionuclide transport and concentration, as postulated in irrigation recycling. In any event, a 
sensitivity study to evaluate the maximum impacts that could occur as a result of irrigation 
recycling shows that the irrigation recycling phenomenon is of low consequence (see 
Supplemental Discussion). Therefore, it is not a significant FEP and can be excluded per 10 
CFR 63.114(e). 
The performance assessment is an analysis that identifies and examines the effects of FEPs on 
the Yucca Mountain disposal system as defined in 10 CFR 63.2 (DIRS 156605). The Yucca 
Mountain disposal system includes natural barriers that prevent or substantially reduce releases 
from the waste. The saturated zone is one of these natural barriers but does not include the 
reference biosphere in which the RMEI is projected to be located. Pursuant to 10 CFR 63.102(j), 
each FEP to be analyzed in the performance assessment relates to the effect of natural conditions, 
rather than human activities, on the performance of the engineered and/or the natural barrier 
systems. As described by the U.S. Environmental Protection Agency in estimating the dose 
incurred by the RMEI, the exposure variations are calculated as a function of the parameters 
that control radionuclide transport from the contamination source (here, the repository) (66 FR 
32074 [DIRS 155216], p. 32089). In other words, the dose the RMEI is projected to receive is 
derived solely from the performance of the repository as affected by the identified FEPs and is 
not to take into account any potential human-induced changes to the geosphere. Conversely, 
there is no indication in the regulations that, once the radionuclides are transported to the 
compliance point, any human-induced changes are to affect the delivered concentration. 
At present, there is no human behavior, including irrigated farming, affecting the groundwater 
between the proposed location of the repository and the 18-km compliance location, or at the 
18-km compliance location itself. In order to avoid the interjection of speculation that cannot be 
scientifically documented and analyzed, 10 CFR 63.305 (DIRS 156605) prohibits the projection 
of changes in society or the biosphere (other than climate). As a consequence, to avoid 
speculation regarding the existence or nature of future human activities, no assumptions are 
made regarding future sites of cultivation or future farming and irrigation practices within the 
controlled area between the repository and the 18-km compliance location or at the 18-km 
compliance location. Human activity that has the potential to affect performance of the 
engineered and natural barrier system is taken into account only in conjunction with determining 
compliance with the single stylized human intrusion scenario set forth in the separate individual 
protection standard of 10 CFR 63.321. By specifying this single instance of human interference 
and no others, the NRC regulations indicate that no other forms of human interference, including 
irrigated farming, are to be considered. 
TSPA Disposition: N/A 
Supporting Reports: N/A 
Supplemental Discussion: 
If human-induced changes to the geosphere were to be considered, a sensitivity analysis confirms 
that the postulated process of irrigation recycling would not result in total recapture of 
radionuclides, and not result in simulated doses that are significantly greater. Losses of 
radionuclide mass from a closed recycling system would occur from nonagricultural uses of 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-93 November 2004 
groundwater and non-capture of contaminated recharge by receptor wells. The steady-state 
solution for a recycling system with losses indicates that contaminant concentrations 
(discounting radioactive decay) would be the same or not greater than a factor of 1.5, relative to 
concentrations with no recycling, in four potential scenarios. Derivation of the steady-state 
solution for radionuclide recycling is presented in Appendix B. 
The ratio of radionuclide concentration in a receptor well for a closed system (with two loss 
mechanisms considered, as discussed above) to the open system receptor well concentration is 
given by the following equation (see attachment for derivation). 
[ ]i c O w
w 
F F C
C 
- 
= 
- 1 
1 (Eq. 6-5) 
Where: Cw = The concentration in the receptor well (Ci/m3) assuming the system is 
closed with two loss mechanisms considered. 
Cw-o = The concentration in the receptor well (Ci/m3) assuming the system is 
open. 
Fc = The fraction of recycled water that is recaptured by the wells. 
Fi = The fraction of the total water demand that is used for agricultural 
irrigation. 
The characteristics of the RMEI and the reference biosphere lead to a set of assumed scenarios 
for use in this sensitivity analysis, consistent with 10 CFR 63.312 and 63.305 (DIRS 156605), 
respectively. Estimates of the closed to open system ratio are used to evaluate the potential 
impacts of recycling. 
The RMEI meets the requirements of 10 CFR 63 (DIRS 156605) in all scenarios. In its 
background information to 40 CFR Part 197 (66 FR 32074 [DIRS 155216], p. 32112), the EPA 
assumed in its determination of the 3,000 acre-ft/year representative volume that 
2550 acre-ft/year is for agricultural use, 100 acre-ft/year for commercial/industrial water use, and 
120 acre-ft/year for individual/municipal water use. Therefore, for all scenarios it is assumed 
that 92 percent of the representative volume is used for irrigation and other uses that potentially 
can contribute to recycling (Fi = 0.92). 
Each scenario below provides an estimate of the fraction of recycled water that is recaptured by 
withdrawal wells. These recapture fractions are based on general hydrologic properties and do 
not explicitly consider well capture properties (i.e., cone of influence). Explicit consideration of 
these properties is expected to reduce the likelihood that such wells would recapture recycled 
contaminant. The closed to open system ratio is determined by comparing pumping demands 
to the aquifer water budget. This ratio represents the likelihood that recycled water is not 
recaptured by the withdrawal well. This approach considers features such as that irrigation is 
applied at a distance from the pumping location and the contaminant plume. 
These sensitivity analyses are simplified and conservative, bounding analyses that do not account 
for all of the other enumerated loss mechanisms or for other realistic circumstances that would 
further reduce the predicted radionuclide concentrations. These analyses do not, in effect, 
represent systems that are entirely open, and instead focus on two significant loss mechanisms 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-94 November 2004 
to provide a more realistic evaluation of the potential impacts of recycling. The scenarios do not 
take into account additional mitigating effects such as crop rotation and the properties of 
withdrawal wells, either of which would reduce the ratios discussed below. In addition, the 
estimates of closed to open system ratios are based on current conditions. Future climate states 
are expected to be wetter, resulting in increased aquifer flow rates, reduced irrigation 
requirements, and lower recapture fractions. These additional assumptions and loss mechanisms 
would further reduce any potential impacts of recycling. 
Scenario 1: Locally Grown Food Produced at Current Location Using Well Water 
Withdrawn at that Location 
In this scenario, locally grown food consumed by the receptor is assumed to be produced in its 
current location, approximately 30 km downgradient from the repository in the Town of 
Amargosa Valley. All water used to produce this food is assumed to be withdrawn at that 
location. Two cases are considered. 
The first case assumes that the concentration of radionuclides withdrawn at 30 km is 
conservatively assumed to be the same as the highest concentration at 18 km and the 
representative volume is 3,000 acre-ft/year. This case is clearly conservative since the annual 
pumping demand at the 30 km location is approximately 14,000 acre-ft/year (as estimated for 
1997) and the total water budget for the Amargosa Desert hydrologic basin is on the order of 
40,000 acre-ft/year (66 FR 32074 [DIRS 155216], p. 32113). 
The second, and more realistic case, considers a 14,000 acre-ft/year water demand. A significant 
amount of dilution and dispersion would occur between the 18-km and 30-km locations, but is 
not explicitly included in this analysis which only focuses on capture fractions. 
In either case, the larger number of farms in this area would effectively spread any contaminant 
across a fairly large area, minimizing the amount of recycled contaminant that would be 
recaptured in the wells. Capture fractions can be estimated using both the representative volume 
(3,000 acre-ft/year) and the actual water demand (14,000 acre-ft/year) as compared to the water 
budget within the Amargosa Desert hydrologic basin (40,000 acre-ft/year). 
Use of the 3,000 acre-ft/year representative volume yields a capture fraction of approximately 
7.5 percent (3,000 acre-ft/year / 40,000 acre-ft / year) and a closed to open system ratio of 
1.07. Using a capture fraction of 35 percent (14,000 acre-ft/year / 40,000 acre-ft/year) yields a 
closed to open system ratio of 1.5. However, although the closed to open system ratio is 
larger in the case of the 14,000 acre-ft/year water demand, the open system radionuclide 
concentration would be significantly smaller due to dilution and dispersion loss mechanisms not 
taken into account in this analysis. 
Scenario 2: Locally Grown Food Produced at Current Location Using Well Water 
Withdrawn at the 18-km Compliance Point 
In this scenario, locally grown food consumed by the receptor is assumed to be produced in its 
current location, 30 km downgradient from the repository in the Town of Amargosa Valley. All 
water used to produce this food is assumed to be withdrawn at the 18-km compliance location. 
Well water would be used to irrigate crops a considerable distance downgradient from the 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-95 November 2004 
withdrawal point. Because the irrigation would occur at 30 km from the repository, the recycling 
of radionuclides would affect the uncontaminated water at this location. Because the 30-km 
location is downgradient of the compliance point, the recycled radionuclides cannot migrate to 
the 18-km compliance point. In this scenario, the irrigation recycling at 30 km would have no 
effect on the radionuclide concentrations in water withdrawn at the 18-km compliance point. 
Scenario 3: Locally Grown Food Produced at the 18-km Compliance Point Using Well 
Water Withdrawn at that Location 
In this scenario, locally grown food consumed by the receptor is assumed to be produced at the 
18-km compliance point. All water used to produce this food is assumed to be withdrawn at the 
18-km compliance location. Agriculture is assumed to occur in the immediate vicinity of the 
wells. This would be unlikely, because the fields would be in the flood zone of Fortymile Wash. 
Under current conditions, the groundwater outflow from the Jackass Flats hydrographic basin 
(227-A), which includes Yucca Mountain and the point of compliance location, is 
8,100 acre ft/year (EPA 1999 [DIRS 143799], p. 8-36). This indicates that approximately 
37 percent (3,000 acre-ft/year / 8,100 acre-ft/year) of the water recaptured by receptor wells 
would be recycled water. This yields a closed to open system ratio of 1.5. 
Scenario 4: Locally Grown Food Produced 18-km Downgradient From the Repository, 
Out of Fortymile Wash, Using Well Water Withdrawn at the 18-km 
Compliance Location 
In this scenario, locally grown food consumed by the receptor is assumed to be produced at the 
18-km compliance point. All water used to produce this food is assumed to be withdrawn at the 
18-km compliance location. However, unlike Scenario 3, agriculture is assumed to occur out of 
Fortymile Wash such that flash flooding does not impact farming. 
Well water would be used to irrigate crops some distance from the withdrawal point. This 
distance would further reduce the likelihood of recycling such that the closed to open system 
ratio would be substantially less than estimated for Scenario 3. 
It is important to note that the steady-state contaminant concentrations due to recycling would 
require a significant period of continuous irrigation at one location with contaminated 
groundwater to develop. For groundwater advection in the unsaturated conditions of the 
alluvium below the irrigated field the advective velocity is defined as: 
 
 
= 
l T 
w
S 
q v 
f 
(Eq. 6-6) 
Where: qw = The vertical groundwater flux (corresponding to the recharge rate due to 
over watering of the irrigated field). 
Sl = The liquid saturation of the alluvium beneath the irrigated field. 
fT = The total porosity of the alluvium. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 6-96 November 2004 
The advective transport velocity of a nonsorbing radionuclide is estimated using representative 
values for these parameters. The recharge rate is taken from the average value of the 
overwatering rate for irrigated alfalfa farming as about 0.15 m/year (BSC 2003 [DIRS 169673], 
Table 6.9-1). The liquid saturation in the alluvium beneath the irrigated fields is estimated to be 
about 0.45 based on the average of measurements of gravimetric moisture content in cores from 
six wells in the Amargosa Farms area (Stonestrom et al. 2003 [DIRS 165862]). The average 
total porosity of alluvium is estimated to be about 0.30 (BSC 2004 [DIRS 170042], 
Section 6.5.2.14). The resulting estimate for the vertical advective velocity of groundwater in 
the UZ beneath the irrigated fields is 1.1 m/year. 
The depth to the water table at the boundary of the accessible environment along the likely SZ 
flow path from the repository can be estimated from information at well NC-EWDP-19P, 
resulting in a depth of 111.7 m to the water table (DTN: GS010908312332.002 [DIRS 163555]). 
Using this depth and the estimated advective velocity, the transport time of a nonsorbing 
radionuclide from beneath an irrigated field to the water table would be approximately 100 years. 
This transport time would constitute one cycle of return flow to the pumping well, and numerous 
cycles would be required to attain the steady-state contaminant concentration in a recycling 
system. The expected transport time of a moderately sorbing radionuclide, such as 237Np, 
beneath the irrigated field to the water table would be about 4,100 years, based on the median 
value of the sorption coefficient of 6.35 mL/g in alluvium (BSC 2004 [DIRS 170042], 
Table 7-1). The depth to the water table at the boundary of the accessible environment would be 
less under future wetter climatic conditions. The transport times of radionuclides from beneath 
an irrigated field to the water table is proportional to the depth of the water table, so transport 
times would also be less. However, water table rise at this location would be significantly less 
than the approximate maximum rise of 100 m at the repository (see Section 6.2.10), because of 
its location closer to potential groundwater discharge areas activated by glacial-transition 
climatic conditions in Amargosa Valley. Consequently, there still would be significantly long 
transport times from beneath an irrigated field to the water table for moderately to strongly 
sorbing radionuclides under future wetter climatic conditions. 
Overall, this sensitivity analysis indicates that the impact of recycling of radionuclides by 
leaching from soils in irrigated fields would be small. Open system behavior resulting from 
non-agricultural uses of groundwater and noncapture of contaminated recharge by receptor wells 
would lead to only small increases in steady-state radionuclide concentrations in groundwater. 
In addition, the estimated transport times of radionuclides in the UZ beneath the irrigated fields 
would require relatively long time periods of continuous irrigation with contaminated 
groundwater for such steady-state conditions to be achieved. This conclusion provides 
additional support for the screening decision to exclude this FEP based on regulatory arguments. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 7-1 November 2004 
7. CONCLUSIONS 
The conclusions from this document (FEP Screening Decision, TSPA Disposition for included 
FEPs, or Screening Argument for excluded FEPs), along with any modifications to the FEP list, 
FEP names, and/or FEP descriptions, are incorporated in the Yucca Mountain TSPA-LA FEP 
database. The FEP database also contains Screening Decisions (Include or Exclude), Screening 
Arguments, and TSPA Dispositions quoted all other FEP reports. 
Table 7.1-1 summarizes the SZ FEP screening decisions. 
Table 7.1-1. Summary of SZ FEPs Screening 
Section 
Number LP FEP Number FEP Name Screening Decision Basis 
6.2.1 1.2.02.01.0A Fractures Included N/A 
6.2.2 1.2.02.02.0A Faults Included N/A 
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 N/A 
6.2.11 1.4.07.01.0A Water management activities Included N/A 
6.2.12 1.4.07.02.0A Wells Included N/A 
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 N/A 
6.2.15 2.2.03.02.0A Rock properties of host rock and 
other units 
Included N/A 
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 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 7-2 November 2004 
Table 7.1-1. Summary of SZ FEPs Screening (Continued) 
Section 
Number LP FEP Number FEP Name Screening Decision Basis 
6.2.19 2.2.07.12.0A Saturated groundwater flow in the 
geosphere 
Included N/A 
6.2.20 2.2.07.13.0A Water-conducting features in the 
SZ 
Included N/A 
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 N/A 
6.2.23 2.2.07.16.0A Dilution of radionuclides in 
groundwater 
Included N/A 
6.2.24 2.2.07.17.0A Diffusion in the SZ Included N/A 
6.2.25 2.2.08.01.0A Chemical characteristics of 
groundwater in the SZ 
Included N/A 
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 N/A 
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 N/A 
6.2.30 2.2.08.09.0A Sorption in the SZ Included N/A 
6.2.31 2.2.08.10.0A Colloidal transport in the SZ Included N/A 
6.2.32 2.2.08.11.0A Groundwater discharge to surface 
within the reference biosphere 
Excluded Low Consequence 
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 N/A 
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 
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 Consequences 
6.2.39 2.2.10.08.0A Thermo-chemical alteration in the 
SZ (solubility, speciation, phase 
changes, precipitation/dissolution) 
Excluded Low Consequences 
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 N/A 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 7-3 November 2004 
Table 7.1-1. Summary of SZ FEPs Screening (Continued) 
Section 
Number LP FEP Number FEP Name Screening Decision Basis 
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 N/A 
6.2.45 3.2.07.01.0A Isotopic dilution Excluded Low Consequence 
6.2.46 1.4.07.03.0A Recycling of accumulated 
radionuclides from soils to 
groundwater 
Excluded By Regulation 
FEP=feature, event, and process; LP=License Position; N/A=not applicable; SZ=saturated zone 
All FEP information, including the 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 list represented by a DTN. Documentation of the FEP database is given in a separate report. 
The final LA FEP list DTN supersedes all of the previous DTNs (e.g., 
DTN: MO0407SEPFEPLA.000 [DIRS 170760]). 
The PRD (Canori and Leitner 2003 [DIRS 166275]) documents and categorizes the regulatory 
requirements and other project requirements and provides a crosswalk to the various YMP 
organizations that are responsible for ensuring that the criteria have been addressed in the LA. 
The regulatory requirements include criteria relevant to performance assessment activities, in 
general, and to FEP-related activities as they pertain to performance assessment, in particular. 
Table 7.2-1 provides a crosswalk between the regulatory requirements, the PRD, and the 
acceptance criteria provided in the YMRP NUREG-1804 (NRC 2003 [DIRS 163274], Sections 
2.2.1.2.1.3 and 2.2.1.2.2.3). 
The cited YMRP criteria (NRC 2003 [DIRS 163274]) are provided in Table 7.1-2. The YMRP 
acceptance criteria for FEP screening echo the regulatory screening criteria of low probability 
and low consequence but also allow for exclusion of a FEP if the process is specifically excluded 
by regulations (see Section 4.2.3). The relevant YMRP acceptance criteria and how they are 
addressed for the SZ FEPs are shown in Table 7.1-2. 

ANL-NBS-MD-000002 REV 03 7-4 November 2004 
Features, Events, and Processes in SZ Flow and Transport 
Table 7.1-2. Relevant YMRP Acceptance Criteria and the Saturated Zone FEPs AMR 
YMRP Section 
Acceptance 
Criterion Description How and where addressed 
1. The 
Identification of a 
list of FEPs Is 
Adequate 
(1) The Safety Analysis Report contains a complete list of FEPs 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. 
The list of saturated zone FEPs is 
presented in Section 1.2, and FEP 
descriptions are presented in Section 6.2. 
Description and origin of the saturated zone 
FEP list and descriptions are presented in 
Section 6.1.1. 
(1) The DOE has identified all FEPs 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 excluded saturated zone FEPs are 
listed in Table 7-1. 
Scenario 
Analysis and 
Event 
Probability: 
Scenario 
Analysis 
(from Section 
2.2.1.2.1.3 
NUREG-1804 
[DIRS 
163274]) 
2. Screening of the 
Initial List of 
Features, Events, 
and Processes Is 
Appropriate (2) The DOE has provided justification for those FEPs that have been 
excluded. An acceptable justification for excluding FEPs is that either 
the FEP is specifically excluded by regulation; probability of the FEP 
(generally an event) falls below the regulatory criterion; or omission of 
the FEP 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. 
See the method and approach discussion 
provided in Section 6.1.2 and the individual 
justification (by regulation, low probability, 
low consequence) for excluding FEPs. The 
justification (basis) is also included in 
Table 7-1. 
(3) The DOE has provided an adequate technical basis for each FEP 
excluded from the performance assessment to support the conclusion 
that either the FEP is specifically excluded by regulation, the probability 
of the FEP falls below the regulatory criterion, or omission of the FEP 
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. 
The individual FEP screening decisions and 
supporting technical bases are discussed in 
Section 6.2. 

ANL-NBS-MD-000002 REV 03 7-5 November 2004 
Features, Events, and Processes in SZ Flow and Transport 
Table 7.1-2. Relevant YMRP Acceptance Criteria and the Saturated Zone FEPs AMR (Continued) 
YMRP Section 
Acceptance 
Criterion Description How and where addressed 
(1) Events or event classes are defined without ambiguity and used 
consistently in probability models, such that probabilities for each event 
or event class are estimated separately. 
See the FEP Description provided for each 
FEP in Section 6.2 and the cited supporting 
AMRs. 
1. Events are 
Adequately Defined 
(2) Probabilities of intrusive and extrusive igneous events are calculated 
separately. Definitions of faulting and earthquakes are derived from the 
historical record, paleoseismic studies, or geological analyses. 
Criticality events are calculated separately by location. 
The individual FEP screening decisions and 
supporting technical bases are discussed in 
Section 6.2. Criticality events and issues 
are not part of the Saturated Zone class of 
FEPs 
2. Probability 
Estimates for 
Future Events Are 
Supported by 
Appropriate 
Technical Bases. 
(1) Probabilities for future natural events have considered past patterns 
of the natural events in the Yucca Mountain region, considering the 
likely future conditions and interactions of the natural and engineered 
repository system. These probability estimates have specifically 
included igneous events, faulting and seismic events, and criticality 
events. 
Future naturally occurring events are 
addressed in the subsections of Section 6.2 
of this analysis report. 
Scenario 
Analysis and 
Event 
Probability: 
Identification of 
Events with 
Probability 
Greater than 
10-8 per Year 
(from Section 
2.2.1.2.2.3 
NUREG-1804 
[DIRS 
163274]) 
5. Uncertainty in 
Event Probability is 
Adequately 
Evaluated 
(1) Probability values appropriately reflect uncertainties. Specifically: 
a. The DOE provides a technical basis for probability values used, 
and the values account for the uncertainty in the probability 
estimates. 
b. The uncertainty for reported probability values adequately reflects 
the influence of parameter uncertainty on the range of model 
results (i.e., precision) and the model uncertainty, as it affects the 
timing and magnitude of past events (i.e., accuracy). 
The technical basis and discussion of 
uncertainties used for exclusion of saturated 
zone FEPs are discussed in the subsections 
of Section 6.2 for the individual FEPs. 
DOE = U.S. Department of Energy; FEP = feature, event, and process. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 7-6 November 2004 
INTENTIONALLY LEFT BLANK 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 8-1 November 2004 
8. INPUTS AND REFERENCES 
The following is a list of the references cited in this document. Column 2 represents the unique 
six-digit numerical identifiers (the Document Input Reference System numbers), which are 
placed in the text following the reference callout (e.g., BSC 2004 [DIRS 166335]). The purpose 
of these numbers is to assist in locating a specific reference. Multiple sources by the same author 
(e.g., BSC 2004) are sorted alphabetically by title. 
8.1 DOCUMENTS CITED 
Arnold, B.W.; Zhang, H.; and Parsons, A.M. 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. Geophysical Monograph 122. Pages 313-322. 
Washington, D.C.: American Geophysical Union. TIC: 255306. 
166335 
Bear, J. 1972. Dynamics of Fluids in Porous Media. Environmental Science Series. 
Biswas, A.K., ed. New York, New York: Elsevier. TIC: 217356. 
156269 
BSC (Bechtel SAIC Company) 2004. Agricultural and Environmental Input 
Parameters for the Biosphere Model. ANL-MGR-MD-000006 REV 02. Las Vegas, 
Nevada: Bechtel SAIC Company. ACC: DOC.20040915.0007. 
169673 
BSC 2004. Biosphere Model Report. MDL-MGR-MD-000001 REV 01. Las Vegas, 
Nevada: Bechtel SAIC Company. ACC: DOC.20041108.0005. 
169460 
BSC 2004. Characterize Framework for Igneous Activity at Yucca Mountain, 
Nevada. ANL-MGR-GS-000001 REV 02. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: DOC.20041015.0002. 
169989 
BSC 2004. Characterize Framework for Seismicity and Structural Deformation at 
Yucca Mountain, Nevada. ANL-CRW-GS-000003 REV 00 Errata 001. Las Vegas, 
Nevada: Bechtel SAIC Company. ACC: MOL.20000510.0175; 
DOC.20040223.0007. 
168030 
BSC 2004. Dissolved Concentration Limits of Radioactive Elements. ANL-WISMD-
000010 REV 03. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20041109.0006. 
169425 
BSC 2004. Evaluation of Features, Events, and Processes (FEP) for the Biosphere 
Model. ANL-MGR-MD-000011 REV 04. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: DOC.20041028.0002. 
169826 
BSC 2004. Features, Events, and Processes in UZ Flow and Transport. 
ANL-NBS-MD-000001 REV 03. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20041108.0004. 
170012

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 8-2 November 2004 
BSC 2004. Features, Events, and Processes: Disruptive Events. 
ANL-WIS-MD-000005 REV 02. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20041108.0002. 
170017 
BSC 2004. Future Climate Analysis. ANL-NBS-GS-000008 REV 01. Las Vegas, 
Nevada: Bechtel SAIC Company. ACC: DOC.20040908.0005. 
170002 
BSC 2004. Hydrogeologic Framework Model for the Saturated Zone Site Scale Flow 
and Transport Model. MDL-NBS-HS-000024, Rev. 00. Las Vegas, Nevada: 
Bechtel SAIC Company. 
170008 
BSC 2004. Initial Radionuclide Inventories. ANL-WIS-MD-000020 REV 01. 
Las Vegas, Nevada: Bechtel SAIC Company. ACC: DOC.20040921.0003. 
170022 
BSC 2004. Mountain-Scale Coupled Processes (TH/THC/THM) Models. 
MDL-NBS-HS-000007 REV 02. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20041108.0001. 
169866 
BSC 2004. Number of Waste Packages Hit by Igneous Intrusion. 
ANL-MGR-GS-000003 REV 01. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20041015.0001. 
170001 
BSC 2004. Probability Distribution for Flowing Interval Spacing. 
ANL-NBS-MD-000003 REV 01. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20040923.0003. 
170014 
BSC 2004. Q-List. 000-30R-MGR0-00500-000-000 REV 00. Las Vegas, Nevada: 
Bechtel SAIC Company. ACC: ENG.20040721.0007. 
168361 
BSC 2004. Recharge and Lateral Groundwater Flow Boundary Conditions for the 
Saturated Zone Site-Scale Flow and Transport Model. ANL-NBS-MD-000010 REV 
01. Las Vegas, Nevada: Bechtel SAIC Company. ACC: DOC.20041008.0004. 
170015 
BSC 2004. Saturated Zone Colloid Transport. ANL-NBS-HS-000031 REV 02. 
Las Vegas, Nevada: Bechtel SAIC Company. ACC: DOC.20041008.0007. 
170006 
BSC 2004. Saturated Zone Flow and Transport Model Abstraction. 
MDL-NBS-HS-000021 REV 02. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20041028.0003. 
170042 
BSC 2004. Saturated Zone In-Situ Testing. ANL-NBS-HS-000039, Rev. 01. 
Las Vegas, Nevada: Bechtel SAIC Company. 
170010 
BSC 2004. Saturated Zone Site-Scale Flow Model. MDL-NBS-HS-000011, Rev. 02. 
Las Vegas, Nevada: Bechtel SAIC Company. 
170037

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 8-3 November 2004 
BSC 2004. Site-Scale Saturated Zone Transport. MDL-NBS-HS-000010 REV 02. 
Las Vegas, Nevada: Bechtel SAIC Company. ACC: DOC.20041103.0004. 
170036 
BSC 2004. Technical Work Plan for: Regulatory Integration Team Revision of 
Features, Events, and Processes (FEPs) Analysis Reports Integration. 
TWP-MGR-PA-000022 REV 00. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20040706.0006. 
170408 
BSC 2004. The Development of the Total System Performance Assessment-License 
Application Features, Events, and Processes. TDR-WIS-MD-000003, Rev. 01. 
Las Vegas, Nevada: Bechtel SAIC Company. 
168706 
BSC 2004. Waste Form and In-Drift Colloids-Associated Radionuclide 
Concentrations: Abstraction and Summary. MDL-EBS-PA-000004 REV 01. 
Las Vegas, Nevada: Bechtel SAIC Company. ACC: DOC.20041028.0007. 
170025 
BSC 2004. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and 
Transport Model. ANL-NBS-HS-000034 REV 02. Las Vegas, Nevada: Bechtel 
SAIC Company. ACC: DOC.20041012.0002. 
170009 
BSC 2004. Yucca Mountain Site Description. TDR-CRW-GS-000001 REV 02 ICN 
01. Two volumes. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20040504.0008. 
169734 
Canori, G.F. and Leitner, M.M. 2003. Project Requirements Document. 
TER-MGR-MD-000001 REV 02. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20031222.0006. 
166275 
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. 
100967 
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. 
160928 
CRWMS (Civilian Radioactive Waste Management System) M&O (Management and 
Operating Contractor) 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. 
103731 
CRWMS M&O 1998. Saturated Zone Flow and Transport Expert Elicitation 
Project. Deliverable SL5X4AM3. Las Vegas, Nevada: CRWMS M&O. 
ACC: MOL.19980825.0008. 
100353

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ANL-NBS-MD-000002 REV 03 8-4 November 2004 
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. 
105347 
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. 
153246 
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. 
100131 
D'Agnese, F.A.; O'Brien, G.M.; Faunt, C.C.; and San Juan, C.A. 1999. Simulated 
Effects of Climate Change on the Death Valley Regional Ground-Water Flow System, 
Nevada and California. Water-Resources Investigations Report 98-4041. Denver, 
Colorado: U.S. Geological Survey. TIC: 243555. 
120425 
DOE (U.S. Department of Energy) 1997. Quality Assurance Surveillance Record, 
Verify Compliance with USGS Procedures in the Preparation of Memorandum 
Report Milestone SPC333M4 Evaluation of Paleo Groundwater Discharge. 
Surveillance No. USGS-SR-97-061. Las Vegas, Nevada: U.S. Department of 
Energy, Office of Civilian Radioactive Waste Management. ACC: 
MOL.19980204.0201. 
171970 
DOE 2004. Quality Assurance Requirements and Description. DOE/RW-0333P, 
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171539 
Domenico, P.A. and Schwartz, F.W. 1990. Physical and Chemical Hydrogeology. 
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100569 
Eckerman, K.F. and Ryman, J.C. 1993. External Exposure to Radionuclides in Air, 
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the 1987 Federal Radiation Protection Guidance. EPA 402-R-93-081. Federal 
Guidance Report No. 12. Washington, D.C.: U.S. Environmental Protection 
Agency, Office of Radiation and Indoor Air. TIC: 225472. 
107684 
EPA (U.S. Environmental Protection Agency) 1999. Background Information 
Document for 40 CFR 197, Environmental Radiation Protection Standards for Yucca 
Mountain, Nevada. Washington, D.C.: U.S. Environmental Protection Agency, 
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143799 
Faunt, C.C. 1997. Effect of Faulting on Ground-Water Movement in the Death 
Valley Region, Nevada and California. Water-Resources Investigations Report 
95-4132. Denver, Colorado: U.S. Geological Survey. ACC: MOL.19980429.0119. 
100146

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Ferrill, D.A.; Winterle, J.; Wittmeyer, G.; Sims, D.; Colton, S.; Armstrong, A.; and 
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118941 
Finsterle, S. 2000. Using the Continuum Approach to Model Unsaturated Flow in 
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151875 
Forester, R.M.; Bradbury, J.P.; Carter, C.; Elvidge, A.B.; Hemphill, M.L.; 
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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. 
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100148 
Freeze, R.A. and Cherry, J.A. 1979. Groundwater. Englewood Cliffs, New Jersey: 
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101173 
French, D.E. 2000. Hydrocarbon Assessment of the Yucca Mountain Vicinity, Nye 
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107425 
Fridrich, C.J.; Dudley, W.W., Jr.; and Stuckless, J.S. 1994. Hydrogeologic 
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100575 
Gauthier, J.H.; Wilson, M.L.; Borns, D.J.; and Arnold, B.W. 1996. Impacts of 
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J. 1998. Analysis of a Multiple-Well Interference Test in Miocene Tuffaceous Rocks 
at the C-Hole Complex, May-June 1995, Yucca Mountain, Nye County, Nevada. 
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129721 
Geldon, A.L.; Umari, A.M.A.; Fahy, M.F.; Earle, J.D.; Gemmell, J.M.; and Darnell, 
J. 1997. Results of Hydraulic and Conservative Tracer Tests in Miocene Tuffaceous 
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Johnson, M.J.; Mayers, C.J.; and Andraski, B.J. 2002. Selected Micrometeorological 
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165069 
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. 
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103282 
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Mountain. EOS, Transactions, 72, (1-26), 121. Washington, D.C.: American 
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163417 
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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 
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103283 
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 
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149850 
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163274 
O'Brien, G.M. 1993. Earthquake-Induced Water-Level Fluctuations at Yucca 
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101276 
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Between a Proposed Repository Site and the Accessible Environment. 
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100783

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 8-7 November 2004 
Paces, J.B.; Whelan, J.F.; Forester, R.M.; Bradbury, J.P.; Marshall, B.D.; and Mahan, 
S.A. 1997. Summary of Discharge Deposits in the Amargosa Valley. Milestone 
SPC333M4. Denver, Colorado: U.S. Geological Survey. 
ACC: MOL.19981104.0151. 
109148 
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. 
106634 
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. 
100644 
Stonestrom, D.A.; Prudic, D.E.; Laczniak, R.J.; Akstin, K.C.; Boyd, R.A.; and 
Henkelman, K.K. 2003. Estimates of Deep Percolation Beneath Native Vegetation, 
Irrigated Fields, and the Amargosa-River Channel, Amargosa Desert, Nye County, 
Nevada. Open-File Report 03-104. Denver, Colorado: U.S. Geological Survey. 
TIC: 255088. 
165862 
Streeter, V.L. and Wylie, E.B. 1979. Fluid Mechanics. 7th Edition. New York, 
New York: McGraw-Hill. TIC: 4819. 
145287 
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. 
100183 
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. 
100088 
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. 
103200 
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. 
129867

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ANL-NBS-MD-000002 REV 03 8-8 November 2004 
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. 
108865 
Wilson, N.S.F.; Cline, J.S.; and Amelin, Y.V. 2003. Origin, Timing, and 
Temperature of Secondary CalciteSilica Mineral Formation at Yucca Mountain, 
Nevada. Geochimica et Cosmochimica Acta, 67, (6), 1145-1176. New York, New 
York: Pergamon. TIC: 254369. 
163589 
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. 
103023 
Ziegler, J.D. 2004. Incorporation of Licensing Position on Radionuclide Recycling 
into the License Application. Letter from J.D. Ziegler (DOE/ORD) to N.H. 
Williams (BSC), November 3, 2004, 1105043829, OLA&S:CMN-0167, with 
enclosure. ACC: MOL.20041104.0455. 
172234 
8.2 CODES, STANDARDS, REGULATIONS, AND PROCEDURES 
10 CFR 63. Energy: Disposal of High-Level Radioactive Wastes in a Geologic 
Repository at Yucca Mountain, Nevada. Readily available. 
156605 
66 FR 32074. 40 CFR Part 197, Public Health and Environmental Radiation 
Protection Standards for Yucca Mountain, NV; Final Rule. Readily available. 
155216 
66 FR 55732. Disposal of High-Level Radioactive Wastes in a Proposed Geologic 
Repository at Yucca Mountain, NV, Final Rule. 10 CFR Parts 2, 19, 20, 21, 30, 40, 
51, 60, 61, 63, 70, 72, 73, and 75. Readily available. 
156671 
AP-2.22Q, Rev. 1, ICN 1. Classification Analyses and Maintenance of the Q-List. 
Washington, D.C.: U.S. Department of Energy, Office of Civilian Radioactive 
Waste Management. ACC: DOC.20040714.0002. 
AP-3.15Q, Rev. 4, ICN 5. Managing Technical Product Inputs. Washington, 
D.C.: U.S. Department of Energy, Office of Civilian Radioactive Waste 
Management. ACC: DOC.20040812.0004. 
AP-SIII.2Q, Rev. 1, ICN 2. Qualification of Unqualified Data. Washington, D.C.: 
U.S. Department of Energy, Office of Civilian Radioactive Waste Management. 
ACC: DOC.20040127.0008. 
AP-SIII.9Q, Rev. 1, ICN 7. Scientific Analyses. Washington, D.C.: U.S. 
Department of Energy, Office of Civilian Radioactive Waste Management. 
ACC: DOC.20040920.0001. 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 8-9 November 2004 
LP-SI.11Q-BSC, Rev. 0, ICN 1. Software Management. Washington, D.C.: U.S. 
Department of Energy, Office of Civilian Radioactive Waste Management. 
ACC: DOC.20041005.0008. 
8.3 SOURCE DATA, LISTED BY DATA TRACKING NUMBER 
GS000808312312.007. Ground-Water Altitudes from Manual Depth-to-Water 
Measurements at Various Boreholes November 1998 through December 1999. 
Submittal date: 08/21/2000. 
155270 
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. 
154734 
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 
GS011108312322.006. Field and Chemical Data Collected between 1/20/00 and 
4/24/01 and Isotopic Data Collected between 12/11/98 and 11/6/00 from Wells in the 
Yucca Mountain Area, Nye County, Nevada. Submittal date: 11/20/2001. 
162911 
GS931100121347.007. Selected Ground-Water Data for Yucca Mountain Region, 
Southern Nevada and Eastern California, Through December 1992. Submittal 
date: 11/30/1993. 
149611 
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. 
145412 
LA0407DK831811.001. Physical Parameters of Basaltic Magma and Eruption 
Phenomena. Submittal date: 07/15/2004. 
170768 
MO0307MWDNPBDC.001. Nominal Performance Biosphere Dose Conversion 
Factors. Submittal date: 07/08/2003. 
164615 
MO0407SEPFEPLA.000. LA FEP List. Submittal date: 07/20/2004. 170760 
SN0402T0503303.004. Number of Waste Packages Hit by Igneous Intrusion. 
Submittal date: 02/13/2004. 
167515 
8.4 SOFTWARE CODES 
LANL (Los Alamos National Laboratory) 2003. Software Code: FEHM. V2.20. 
SUN, PC. 10086-2.20-00. 
161725 
SNL (Sandia National Laboratories) 2003. Software Code: SZ_Convolute. V2.2. 
PC, Windows 2000. 10207-2.2-00. 
163344

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APPENDIX A 
QUALIFICATION OF UNQUALIFIED DATA 

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A1. QUALIFICATION OF ANALYSIS FROM PALEO-SPRING DEPOSITS IN THE 
NORTHERN AMARGOSA DESERT 
Some analyses used as direct input were obtained from outside sources. These data are 
demonstrated in this appendix to be suitable for use within this report, in accordance with 
AP-SIII.2Q, Qualification of Unqualified Data, and AP-SIII.9Q, Scientific Analyses. 
A1.1 DATA FOR QUALIFICATION 
Summary of Discharge Deposits in the Amargosa Valley (Paces et al. 1997 [DIRS 109148]) was 
prepared by the Environmental Science Team, Earth Science Investigations Program, YMP 
Branch, Water Resources Division of USGS regarding activities conducted in association with 
Milestone SPC333M4, Evaluation of Paleo Ground-Water Discharge (USGS 1997 
[DIRS 171970]). This USGS report analyzes age, isotope, and paleontological data and 
summarizes the current understanding and implications of paleo-spring deposits located in the 
Amargosa Valley area. 
The USGS report (Paces et al. 1997 [DIRS 109148]) is cited as direct input in this analysis report 
to exclude FEP 2.2.08.11.0A, Groundwater Discharge to Surface Within the Reference 
Biosphere on the basis of low consequence. 
A1.2 QUALIFICATION METHOD AND RATIONALE FOR SELECTION 
The data qualification was performed in accordance with the data qualification plan 
(Figure A-1), developed according to AP-SIII.2Q. The Equivalent QA Program method, 
described in Attachment 3 of AP-SIII.2Q Rev.1 ICN 2, was selected for use. This method was 
chosen, because the YMP Branch of the USGS has worked in cooperation with the YMP 
Management and Operating Contractor for many years, and USGS Milestone SPC333M4, 
(USGS 1997 [DIRS 171970]) activities underwent a DOE Office of Quality Assurance (OQA) 
surveillance in late 1997. The objective of the surveillance was to verify compliance with USGS 
technical and implementing procedures in the production of the milestone. 

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Figure A-1. Qualification of Analysis from Paleo-Spring Deposits in the Northern Amargosa Desert 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 A-3 November 2004 
A1.3 EVALUATION CRITERIA 
The evaluation criteria are based on the requirements in Attachment 3 and the applicable 
qualification attributes listed in Attachment 4 of AP-SIII.2Q. Use of qualification Method 1, 
Equivalent QA Program, requires that an initial evaluation of the data quality and correctness be 
made by comparing the methods used to plan, collect, and analyze the data against generally 
accepted scientific or engineering practices. If this comparison is adequate, then the acquisition, 
development, or processing of data must be demonstrated to be functionally equivalent (i.e., 
similar in scope and implementation) to the general process requirements of the Quality 
Assurance Requirements and Description (QARD) (DOE 2004 [DIRS 171539]). A condition of 
this method is that the qualification team assess the functional equivalence of the data-gathering 
process to applicable QARD concepts, as identified by the attributes in AP-SIII.2Q, Attachment 
4 (e.g., Attributes 1, 2, 5, 6, 8, and/or 11). These attributes are listed here: 
 Qualification Attribute 1Qualifications of personnel or organizations generating the 
data are comparable to qualification requirements of personnel generating similar data 
under approved 10 CFR 60, Subpart G, program. 
 Qualification Attribute 2The technical adequacy of equipment and procedures used 
to collect and analyze the data. 
 Qualification Attribute 5The quality and reliability of the measurement control 
program under which the data were generated. 
 Qualification Attribute 6The extent to which conditions under which the data were 
generated may partially meet 10 CFR 60, Subpart G. 
 Qualification Attribute 8Prior peer or other professional reviews of the data and their 
results. 
 Qualification Attribute 11The degree to which independent audits of the process that 
generated the data were conducted. 
A1.4 EVALUATION RESULTS 
In the initial evaluation of data quality and correctness, Paces et al. (1997 [DIRS 109148]) 
analyze the new age, isotope, and paleontological data and present an interpretive evaluation on 
past discharge activity in the northern Amargosa Valley. Thermoluminescence data, stable 
isotope data (O and C), other isotope data (Sr and U-series disequilibrium), as well as diatom and 
ostracode (paleontological) data, are generally accepted by the scientific (geologic and 
hydrologic) community for use in determining age, temperature, climatic, and environmental 
conditions of paleo flowing springs. Standard geologic field practices were used for sampling 
from trench wall and natural outcrops, mass spectrometry was used in collecting isotopic data, 
and thermoluminescence data were collected by a commonly accepted technique. A list of all 
procedures used for this activity are found in OQA surveillance record No. USGS-SR-97-061 
(USGS 1997 [DIRS 171970], Item 8). These technical procedures are all USGS approved. The 

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data quality and correctness are determined to be adequate for the implementation of the 
Equivalent QA Program qualification method. 
OQA Surveillance No. USGS-SR-97-061 (USGS 1997 [DIRS 171970]) was conducted to verify 
compliance with USGS procedures in the preparation of memorandum report Milestone 
SPC333M4, Evaluation of Paleo Ground-Water Discharge, September 23 through October 3, 
1997. The conclusion of the surveillance was that the USGS has adequately implemented the 
QA program as it applied to the activities conducted in association with Milestone SPC333M4. 
No deficiency documents were issued as a result of this surveillance. 
The results of assessment of the functional equivalence of the data-gathering process to 
applicable QARD (DOE 2004 [DIRS 171539]) concepts, as identified by the attributes in 
Attachment 4, AP-SIII.2Q, are the following: 
 Qualification Attribute 1Surveillance record No. USGS-SR-97-061 (USGS 1997 
[DIRS 171970]), Items 1 and 2, and Attachment 1 indicate that the qualification of 
personnel generating the data are comparable to those qualifications approved by the 10 
CFR 60, Subpart G (DIRS 156605) program. 
 Qualification Attribute 2Items 3, 4, 8, and 10 of the surveillance record (USGS 1997 
[DIRS 171970]) demonstrate the technical adequacy of equipment and procedures used 
to collect and analyze the data. 
 Qualification Attribute 5Items 3, 4, 5, 6, 7, 8, and 10 of the surveillance record 
(USGS 1997 [DIRS 171970]) demonstrate the quality and reliability of the measurement 
control program under which the data were generated. 
 Qualification Attribute 6The surveillance record determined that the USGS has 
adequately implemented a QA program as it applies to activities associated with 
Milestone SPC333M4 (USGS 1997 [DIRS 171970]). This conclusion was based on 
objective evidence and discussions with USGS personnel. There were no deficiency 
documents issued as a result of the surveillance. The conditions under which the data 
were generated partially meet 10 CFR 60, Subpart G (DIRS 156605). 
 Qualification Attribute 8Item 11 of the surveillance record (USGS 1997 
[DIRS 171970]) demonstrates that technical reviews were done before the data packages 
were sent to the YMP. Dr. Zell Peterman, Chief of the USGS YMPB Environmental 
Science Team, conducted a management review. 
 Qualification Attribute 11There were no independent audits conducted in association 
with the data generation process. 
A1.5 EVALUATION RECOMMENDATION 
The evaluation found that the USGS report (Paces et al. 1997 [DIRS 109148]) analyses data 
were adequate for the implementation of the Equivalent QA Program qualification method. The 

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Equivalent QA Program method was used to determine that qualification Attributes 1, 2, 5, 6, 
and 8 (Attachment 4, AP-SIII.2Q) were satisfied by the USGS QA program. The USGS QA 
program was found to be the functional equivalent to the general processes required by the 
QARD (DOE 2004 [DIRS 171539]). Consequently, it is recommended that the USGS report be 
qualified for use as direct input within this analysis report. 
A2. JUSTIFICATION OF DATA FROM OUTSIDE SOURCES 
The following information is being provided to justify that these data are suitable for the 
intended use and are qualified for use in this report. 
A2.1 JUSTIFICATION FOR USING JOURNAL ARTICLE 
Paleoclimatic Inferences from a 120,000-year Calcite Record of Water-Table Fluctuation in 
Browns Room of Devils Hole, Nevada (Szabo et al. 1994 [DIRS 100088]) is a professional 
journal article. Submissions to Quaternary Research undergo a peer review before acceptance. 
The petrographic and morphologic differences between calcite precipitated below, at, or above 
the present water table and uranium-series dating were used to reconstruct a chronology of 
water-table fluctuation for the past 120,000 years in Browns Room. This location is a 
subterranean air-filled chamber of Devils Hole fissure adjacent to the discharge area of the large 
Ash Meadows groundwater flow system in southern Nevada. The chronology of water-table 
fluctuation permits the following interpretations: 
 Past climate fluctuations are cyclical and are propagated through the unsaturated zone to 
saturated zone. 
 Calcite crystal formation is a function of degree of saturation. 
 Evidence of past water table elevations is seen in crystal morphology and growth in 
Browns Room. 
 Crystal morphology in Browns Room indicates the water table dropped by at least 6 m 
between 53,000 and 92,000 years ago. 
 The current climate represents an extremely arid condition. 
A2.2 JUSTIFICATION FOR USING HYDROLOGY TEXTBOOK 
Groundwater (Freeze and Cherry 1979 [DIRS 101173]) is a hydrology textbook. Technical 
information in the book has undergone peer review before publication. This book is designed for 
use as a text in introductory groundwater courses of the type normally taught in the junior or 
senior year of college undergraduate geology, geological engineering, or civil engineering 
curricula. Technical information presented in the textbook and used in this report includes 
(1) carbonate and halite solubilities, which are important in describing how volcanic rocks tend 
to weather to clay minerals with a relatively small amount of silica going into solution, and 
(2) the equation for retardation factor for flow in the saturated zone. 

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A2.3 JUSTIFICATION FOR USING NATIONAL RESEARCH COUNCIL REPORT 
The National Research Council (1992 [DIRS 105162]) reference provides the basis for regional 
extensional rates declining from a peak of 10-30 mm/year, 10-12 ma, to 5-10 mm/year 5 ma 
and are in a declining state today. The reference also predicts a rise in water table given future 
seismic events. Numerical results using a seismic dislocation model indicate the maximum 
rise would be approximately 10 m. 
A2.3.1 Extent to which the Data Demonstrate the Properties of Interest 
Seismic dislocation and water-level changes are discussed in a report prepared by the Panel on 
Coupled Hydrologic/Tectonic/Hydrothermal Systems at Yucca Mountain, commissioned by 
the National Research Council. The panel reviewed an alternative conceptual model that 
predicted large changes in groundwater level, and concluded that the model was infeasible. 
The panel stated that seismic dislocation would at most elevate the water levels a few tens of 
meters (National Research Council 1992 [DIRS 105162]), page 7). 
A2.3.2 Reliability of Data Source 
The project that is the subject of this report was approved by the governing board of the 
National Research Council, whose members are drawn from the councils of the National 
Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. 
The members of the committee responsible for the report were chosen for their special 
competencies and with regard for appropriate balance. This report has been reviewed by a 
group other than the authors according to procedures approved by a Report Review Committee 
consisting of members of the National Academy of Sciences, the National Academy of 
Engineering, and the Institute of Medicine. 
PANEL ON COUPLED PROCESSES AT YUCCA MOUNTAIN: 
C. BARRY RALEIGH, University of Hawaii, Chairman 
GEORGE A. THOMPSON, Stanford University, Vice-Chairman 
WILLIAM F. BRACE, Massachusetts Institute of Technology (ret.) 
BARRY H. G. BRADY, DowellSchlumberger 
JOHN D. BREDEHOEFT, U. S. Geological Survey 
RAYMOND M. BURKE, Humboldt State University 
ROBERT O. FOURNIER, U. S. Geological Survey 
SABODH K. GARG, SCubed 
GEORGE M. HORNBERGER, University of Virginia 
ROBIN K. McGUIRE, Risk Engineering, Inc. 
AMOS M. NUR, Stanford University 
H. J. RAMEY, Stanford University 
EDWIN W. ROEDDER, Harvard University 
DOUGLAS RUMBLE, Geophysical Laboratory, Carnegie Institution of Washington 
W. GEOFFREY SPAULDING, Dames & Moore 
BRIAN P. WERNICKE, California Institute of Technology 
MARY LOU ZOBACK, U. S. Geological Survey 

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The report was published by the National Academies Press (NAP). The NAP was created by the 
National Academies to publish the reports issued by the National Academy of Sciences, the 
National Academy of Engineering, the Institute of Medicine, and the National Research Council, 
all operating under a charter granted by the Congress of the United States. NAP publishes over 
200 books a year on a wide range of topics in science, engineering, and health, capturing the 
most authoritative views on important issues in science and health policy. The institutions 
represented by NAP are unique in that they attract the nation's leading experts in every field to 
serve on their blue ribbon panels and committees. 
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of 
distinguished scholars engaged in scientific and engineering research, dedicated to the 
furtherance of science and technology and to their use for the general welfare. Upon the 
authority of the charter granted to it by Congress in 1863, the Academy has a mandate that 
requires it to advise the federal government on scientific and technical matters. 
The National Research Council was organized by the National Academy of Sciences in 1916 to 
associate the broad community of science and technology with the Academy's purposes of 
furthering knowledge and of advising the federal government. Functioning in accordance with 
general policies determined by the Academy, the Council has become the principal operating 
agency of both the National Academy of Sciences and the National Academy of Engineering in 
providing services to the government, the public, and the scientific and engineering 
communities. The Council is administered jointly by both Academies and the Institute of 
Medicine. 

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APPENDIX B 
DERIVATION OF THE CLOSED (WITH LOSSES) TO OPEN SYSTEM RECEPTOR 
WELL CONCENTRATION RATIO 

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B1. DERIVATION OF THE CLOSED (WITH LOSSES) TO OPEN SYSTEM 
RECEPTOR WELL CONCENTRATION RATIO 
A control volume that contains the entire receptor wellbiosphere system is defined to determine 
the time-dependent contaminant mass within the volume. This control volume assumes that 
contaminated water used for irrigation is recycled back to the well. Boundary conditions are (1) 
the introduction of contaminant from the saturated zone, (2) the removal of contaminant from the 
system through the use of groundwater for purposes other than irrigation, and (3) any recycled 
contaminant that is not captured by the receptor wells. The inherent assumption is that the entire 
contaminant plume arriving from the saturated zone is intercepted by the receptor wells. This 
control volume is shown schematically below. 
m 
V 
Q 
w
D I - 
m 
V
Q
S
L 
sz m& 
Figure B-1. Diagram of the Control Volume for Radionuclide Recycling 
The differential equation that describes the change in contaminant mass within the control 
volume as a function of time is given by Equation B-1: 
. .. 
. 
. .. 
. 
+ - = - 
s
L 
w
D I 
sz V
Q 
V 
Q 
m m 
t 
m & 
d 
d (Eq. B-1) 
where: 
m = mass of contaminant in the control volume (kg) 
sz m& = mass flux of contaminant entering the control volume from the saturated 
zone (kg/year) 
QI-D = amount of water used annually for purposes other than irrigation 
(acre-ft/year) 
QL = amount of contaminated recycled water annually lost from the system 
(amount that is not captured by the receptor wells) (acre-ft/year) 
Vw = volume of the well (m3) 
Vs = volume of the soil that contaminated water is used to irrigate (m3) 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 B-2 November 2004 
This equation becomes: 
. .. 
. 
. .. 
. 
+ = 
= + 
- 
s
L 
w
D I 
sz 
V
Q 
V 
Q Z
m Zm 
t 
m 
: Where 
d 
d & 
(Eq. B-2) 
This is a linear, first-order differential equation that takes on the following solution: 
C dt Zdt m Zdt 
sz + . = . .e e m & (Eq. B-3) 
Which becomes: 
. .. 
. 
. .. 
. 
+ =
- + = 
- 
s
L 
w
D I 
sz 
V
Q 
V 
Q 
Z 
Zt Ce 
Z 
m 
m 
: Where
& 
(Eq. B-4) 
or: 
t 
V
Q 
V 
Q 
Ce 
V
Q 
V 
Q 
m 
m s
L 
w
D I 
s
L 
w
D I 
sz 
. .. 
. 
. .. 
. 
+ - 
+ 
. .. 
. 
. .. 
. 
+ 
= 
- 
- 
& 
(Eq. B-5) 
Initially, the mass in the control volume is equal to zero, which results in: 
. .. 
. 
. .. . 
+ 
- = 
- 
s
L 
w
D I 
sz 
V
Q 
V 
Q 
m 
C 
& 
(Eq. B-6) 
Thus, the equation that defines the time-dependent mass in the control volume becomes: 
t 
V
Q 
V 
Q 
e 
V
Q 
V 
Q 
m 
V
Q 
V 
Q 
m 
m s
L 
w
D I 
s
L 
w
D I 
sz 
s
L 
w
D I 
sz 
. .. 
. 
. .. 
. 
+ - 
. .. 
. 
. .. 
. 
+ 
- 
. .. 
. 
. .. 
. 
+ 
= 
- 
- - 
& & 
(Eq. B-7) 

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ANL-NBS-MD-000002 REV 03 B-3 November 2004 
or: 
. . . . . 
.
. 
. . . . . 
.
. 
. .. 
. 
. .. 
. 
+ - 
- 
. .. 
. 
. .. 
. 
+ 
= 
- 
- 
t 
V
Q 
V 
Q 
e 
V
Q 
V 
Q 
m 
m s
L 
w
D I 
s
L 
w
D I 
sz 1 
& 
(Eq. B-8) 
The purpose in developing this equation is not to explicitly calculate the time-dependent mass of 
contaminant in the control volume. Rather, this equation shows that losses will ultimately cause 
the system to arrive at steady-state conditions. 
The overall control volume above is next divided into two control volumes: one for the receptor 
wells and one for the surface soil. These control volumes and the in-flows and out-flows from 
each are shown below. Note that the transfer of contaminant along other transport pathways in 
the biosphere is ignored. 
Soil Control 
Volume 
Well Control 
Volume 
w LC Q s s L c V C F . 
s s L c V C F . ) 1 ( - 
sz m& w D I C Q - 
Figure B-2. Diagram of the Control Volumes for Receptor Wells and Surface Soils 
Two coupled differential equations define the rate of change of contaminant mass within each of 
the control volumes. 
s s L w I 
s 
w D I w I s s L c sz 
w 
V C C Q 
t 
m 
C Q C Q V C F m 
t 
m 
.
. 
- = 
- - + = - 
d 
d 
: SOIL 
d 
d 
: WELL & 
(Eq. B-9) 
QICw

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 B-4 November 2004 
Where: 
mw = mass of contaminant in the well control volume (kg) 
ms = mass of contaminant in the soil control volume (kg) 
Cw = concentration of contaminant in the well (kg/m3) 
Cs = concentration of contaminant in the soil (kg-contaminant/kg-soil) 
sz m& = mass flux of contaminant entering the control volume from the saturated 
zone (kg/year) 
Vw = volume of the well in the control volume (m3) 
Vs = volume of the surface soil in the control volume (m3) 
QI-D = amount of water used annually for purposes other than irrigation 
(acre-ft/year) 
QI = amount of recycled water used annually for irrigation (acre-ft/year) 
.L = leach rate of contaminant from the soil (year-1) 
Fc = the fraction of recycled water that is recaptured by the wells. 
The derivation above demonstrates that ultimately, the entire system will reach a steady state 
condition. As such, the two control volume system will also reach a steady state, and both 
differential equations can be set to zero. This results in the following relation (from the soil 
equation): 
L 
w I 
s s 
C Q V C 
. 
= (Eq. B-10) 
and (from the well equation): 
0 = - - + - w D I w I 
L 
w I 
L c sz C Q C Q C Q F m 
. 
. & (Eq. B-11) 
This becomes: 
[ ] 0 = - - + - w D I I I c sz C Q Q Q F m& (Eq. B-12) 
Solving for Cw gives: 
I c I D I 
sz 
w Q F Q Q 
m C 
- + 
= 
- 
& (Eq. B-13) 
The total amount of water withdrawn, QT equals QI-D + QI. The amount of water used for 
irrigation is also a fraction of the total amount of water withdrawn, giving QI equal to Fi QT. So, 
the steady state concentration of contaminant in the well assuming a portion of the contaminant 
mass is recycled from the soil to the water table becomes: 

Features, Events, and Processes in SZ Flow and Transport 
ANL-NBS-MD-000002 REV 03 B-5 November 2004 
[ ]i c T 
sz 
T i c T 
sz 
w F F Q 
m 
Q F F Q 
m C 
- 
= 
- 
= 
1 
& & (Eq. B-14) 
The open-system concentration of contaminant in the well is defined as the well concentration 
assuming no recycling of contaminant. This is given as: 
T
sz 
O w Q
m C & = - (Eq. B-15) 
So, the maximum increase in the contaminant concentration in the well as a result of recycling is 
given by the following: 
[ ] 
[ ]i c 
T
sz 
i c T 
sz 
O w
w 
F F 
Q
m 
F F Q 
m 
C
C 
- 
= - = 
- 1 
1 1 
&
& 
(Eq. B-16) 

Features, Events, and Processes in SZ Flow and Transport 
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INTENTIONALLY LEFT BLANK