Features, Events and Processes: Disruptive Events 
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2 December 2003 Features, Events and Processes: Disruptive Events 
CONTENTS 
3 
Page 
ACRONYMS AND ABBREVIATIONS....................................................................................... 6 
1. PURPOSE........................................................................................................................ 9 
1.1 PLANNING AND DOCUMENTATION ..................................................................... 10 
1.2 SCOPE.......................................................................................................................... 10 
1.3 SCIENTIFIC ANALYSIS USE AND LIMITATIONS ................................................ 11 
2. QUALITY ASSURANCE...................................................................................................... 13 
3. COMPUTER SOFTWARE AND MODEL USAGE............................................................. 15 
4. INPUTS......................................................................................................................... 17 
4.1 DIRECT INPUTS .......................................................................................................... 17 
4.1.1 Data-Qualified and Factual Information............................................................ 17 
4.1.2 Product Outputs ................................................................................................. 20 
4.1.2.1 YMP FEP Database and Included FEPs............................................ 20 
4.1.2.2 Information Exchange Drawings....................................................... 21 
4.1.2.3 Product Output and Preliminary Technical Information Used 
for DE FEP Exclusion........................................................................................ 22 
4.1.3 Other Technical Information ............................................................................. 23 
4.1.3.1 Regulations that Provide Direct Input for FEP Screening ................ 23 
4.1.3.2 Other Technical Information ............................................................. 28 
4.2 CRITERIA..................................................................................................................... 28 
4.3 CODES AND STANDARDS........................................................................................ 30 
5. ASSUMPTIONS.................................................................................................................... 35 
6. SCIENTIFIC ANALYSES ..................................................................................................... 37 
6.1 METHOD AND APPROACH ...................................................................................... 37 
6.1.1 DE FEPs Origin and Identification.................................................................... 37 
6.1.2 FEP Screening Process ...................................................................................... 49 
6.1.2.1 Exclusion by Low Probability........................................................... 50 
6.1.2.2 Exclusion by Low Consequence ....................................................... 50 
6.1.2.3 Exclusion by Regulation ................................................................... 52 
6.1.3 Background, Supporting AMRs, Technical Information, and Literature Searches...... 52 
6.1.4 Assumptions and Simplifications, Alternative Conceptual Models, and 
Consideration of Uncertainty in FEP Screening................................................ 55 
6.1.5 Alternative Approaches, Mathematical Formulations, and Units of Measure .. 56 
6.1.6 Model and Software Issues for Previously Developed and Validated Models.. 57 
6.1.7 Intended Use and Limitations............................................................................ 57 
6.2 DISRUPTIVE EVENTS FEP EVALUATION AND ANALYSIS .............................. 57 
6.2.1 Seismic-Related FEPs........................................................................................ 58 
6.2.1.1 Tectonic ActivityLarge Scale (1.2.01.01.0A) ............................... 58 
December 2003 
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CONTENTS (Continued) 
Page 
6.2.1.2 Fault Displacement Damages EBS Components 
(1.2.02.03.0A)..........................................................................70 
6.2.1.3 Seismic Ground Motion Damages EBS Components 
(1.2.03.02.0A) ................................................................................... 77 
6.2.1.4 Seismic-induced Rockfall Damages EBS Components 
(1.2.03.02.0B).................................................................................... 80 
6.2.1.5 Seismic-induced Drift Collapse Damages EBS Components 
(1.2.03.02.0C).................................................................................... 84 
6.2.1.6 Seismic-Induced Drift Collapse Alters In-drift 
Thermohydrology (1.2.03.02.0D) ..................................................... 88 
6.2.1.7 Seismicity Associated with Igneous Activity (1.2.03.03.0A) ........... 90 
6.2.1.8 Hydrologic Response to Seismic Activity (1.2.10.01.0A) ................ 93 
6.2.1.9 Seismic Activity Changes Porosity and Permeability of Rock 
(2.2.06.01.0A) ................................................................................... 95 
6.2.1.10 Seismic Activity Changes Porosity and Permeability of Faults 
(2.2.06.02.0A) ................................................................................... 98 
6.2.1.11 Seismic Activity Changes Porosity and Permeability of 
Fractures (2.2.06.02.0B).................................................................. 103 
6.2.1.12 Seismic Activity Alters Perched Water Zones (2.2.06.03.0A) ....... 108 
6.2.2 Igneous-Related FEPs...................................................................................... 109 
6.2.2.1 Igneous Activity Changes Rock Properties (1.2.04.02.0A) ............ 110 
6.2.2.2 Igneous Intrusion Into Repository (1.2.04.03.0A) .......................... 114 
6.2.2.3 Igneous Intrusion Interacts with EBS Components 
(1.2.04.04.0A) ................................................................................. 121 
6.2.2.4 Magma or Pyroclastic Base Surge Transports Waste 
(1.2.04.05.0A) ................................................................................. 126 
6.2.2.5 Eruptive Conduit to Surface Intersects Repository 
(1.2.04.06.0A) ................................................................................. 131 
6.2.2.6 Ashfall (1.2.04.07.0A)..................................................................... 136 
6.2.2.7 Ash Redistribution via Soil and Sediment Transport 
(1.2.04.07.0C).................................................................................. 139 
6.2.2.8 Hydrologic Response to Igneous Activity (1.2.10.02.0A) .............. 141 
7. CONCLUSIONS................................................................................................................... 149 
8. INPUTS AND REFERENCES............................................................................................. 150 
8.1 DOCUMENTS CITED................................................................................................ 150 
8.2 CODES, STANDARDS, REGULATIONS, AND PROCEDURES........................... 159 
8.3 SOURCE DATA.......................................................................................................... 160 
ATTACHMENT A..................................................................................................................... A-1 
December 2003 4 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
4-1. 
4-2. 
4-3. 
4-4. 
4-5. 
4-6. 
4-7. 
6-1. 
6-2. 
6-3. 
6-4. 
6-5. 
ANL-WIS-MD-000005 REV 01 
TABLES 
5 
Page 
Data-Qualified and Factual Information Used for DE FEP Exclusion...........................17 
Included DE FEPs and Supporting AMRs......................................................................20 
Drawings and Design Documents Used as Basis for DE FEP Exclusion.......................21 
Specific Product Output Used for DE FEP Exclusion....................................................22 
Direct Input from Regulations Used for DE FEP Exclusion ..........................................25 
Relationship of EPA and NRC Regulations to the PRD and the Acceptance 
Criteria from YMRP .......................................................................................................28 
YMRP Criteria and the DE FEPs AMR. ........................................................................31 
Changes to the DE FEPs from TSPA-SR to TSPA-LA..................................................39 
Supporting AMRs Used to Quantify Seismic-Related FEPs..........................................53 
Supporting AMRs Used to Quantify Igneous-Related FEPs..........................................54 
Annualized Frequency of Exceedance and Displacements forVarious Locations 
within the TSPA-LA Repository Footprint.....................................................................71 
Calculation of Shallowest Depth of Waste Emplacement Drifts..................................130 
December 2003 Features, Events and Processes: Disruptive Events 
BSC 
CDF 
CFR 
CRWMS 
CSNF 
ICN 
ka 
Ma 
M&O 
Mw 
NBS 
NEA 
NRC 
NTS 
OCRWM 
PGV 
PRD 
ACRONYMS AND ABBREVIATIONS 
AMR analysis model report 
AMRs analysis model reports 
AP administrative procedure 
Bechtel-SAIC Company, LLC 
cumulative distribution function 
Code of Federal Regulations 
Civilian Radioactive Waste Management System 
commercial spent nuclear fuel 
defense high-level (radioactive) waste 
U.S. Department of Energy 
Discrete Regional Key Block Analysis 
defense spent nuclear fuel 
Data Tracking Number 
DE disruptive events 
DHLW 
DOE 
DRKBA 
DSNF 
DTN 
Enhanced Characterization of the Repository Block 
U.S. Environmental Protection Agency 
EBS engineered barrier system 
ECRB 
EPA 
ESF Exploratory Studies Facility 
FEP feature, event, and process 
FR Federal Register 
Interim Change Notice 
thousand years (before present) 
LA license application 
million years (before present) 
Management and Operating Contractor 
moment magnitude ( a measure of earthquake magnitude) 
natural barrier system 
U.S. Nuclear Energy Agency 
U.S. Nuclear Regulatory Commission 
Nevada Test Site 
Office of Civilian Radioactive Waste Management 
peak ground velocity 
Project requirements document 
6 ANL-WIS-MD-000005 REV 01 December 2003 Features, Events and Processes: Disruptive Events 
PSHA 
PVHA 
RMEI 
YMP 
YMRP 
ACRONYMS AND ABBREVIATIONS (Continued) 
Probabilistic Seismic Hazard Analyses for Fault Displacement and Vibratory 
Ground Motion at Yucca Mountain, Nevada 
PTn Paintbrush, nonwelded tuff 
PWR pressurized water reactor 
Probabilistic Volcanic Hazard Analysis for Yucca Mountain, Nevada 
QA quality assurance 
QARD Quality Assurance Requirements and Description 
reasonably maximally exposed individual 
Scientific Processes Guidelines Manual 
SDS seismicity and structural deformation 
SME subject-matter expert 
SPGM 
SR site recommendation 
SZ saturated zone 
technical work plan 
TBV to be verified 
TSPA total system performance assessment 
TSPA-SR total system performance assessment for site recommendation 
TPSA-LA total system performance assessment for license application 
TWP 
USGS U.S. Geological Survey 
UZ unsaturated zone 
Yucca Mountain Project 
Yucca Mountain Review Plan 
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8 December 2003 Features, Events and Processes: Disruptive Events 
addressed in Section 6.1. 
1. PURPOSE 
The primary purpose of this analysis is to evaluate seismic- and igneous-related features, events, 
and processes (FEPs). These FEPs represent areas of natural system processes that have the 
potential to produce disruptive events (DE) that could impact repository performance and are 
related to the geologic processes of tectonism, structural deformation, seismicity, and igneous 
activity. Collectively, they are referred to as the DE FEPs. This evaluation determines which of 
the DE FEPs are excluded from modeling used to support the total system performance 
assessment for license application (TSPA-LA). The evaluation is based on the data and results 
presented in supporting analysis reports, model reports, technical information, or corroborative 
documents that are cited in the individual FEP discussions in Section 6.2 of this analysis report. 
By default, FEPs are included in the TSPA-LA unless they can be excluded based on low 
probability, low consequence, or by regulation. The U. S. Nuclear Regulatory Commission 
(NRC) provides the evaluation criteria, or screening criteria, in the Code of Federal Regulations 
(CFR) at 10 CFR Part 63.114(d, e, and f) (66 Federal Register (FR) 55732 [DIRS 156671]). The 
NRC regulations also incorporate the performance standards of the U.S. Environmental 
Protection Agency (EPA) found at 40 CFR Part 197 (66 FR 32074 [DIRS 155216]). A FEP can 
be excluded from the TSPA-LA per 10 CFR 63.114(d) (66 FR 55732 [DIRS 156671]) by 
showing that the probability of occurrence is less than 1 in 10,000 in 10,000 years (or an 
approximately equivalent annualized probability of 10-8). A FEP also can be excluded from the 
TSPA-LA per 10 CFR 63.114(e or f) (66 FR 55732 [DIRS 156671]), by showing that omitting 
the FEP would not significantly change the resulting radiological exposure to the reasonably 
maximally exposed individual (RMEI) or change the radionuclide release to the accessible 
environment. In a few instances, FEPs may also be excluded by regulation based on 
characteristics, definitions, or concepts specifically stated in applicable NRC and EPA 
regulations. Results of the FEP evaluations are such that the DE FEPs are either included or are 
excluded based on low consequence. 
This revision addresses updates in the Yucca Mountain Project (YMP) administrative procedures 
as they pertain to this analysis report; the current procedures are discussed in Section 2. 
Sections 4 and 6 incorporate updates to the technical basis that are provided in supporting 
analysis model reports (AMRs) and also provide additional information pertaining to the relevant 
FEP-related acceptance criteria presented in the Yucca Mountain Review Plan, Final Report 
NUREG-1804 (NRC 2003, [DIRS 163274]), herein referred to as the YMRP. 
More importantly, this report documents changes to the DE FEP list that have occurred since 
issuance of REV 00 ICN 01 (CRWMS M&O 2000 [DIRS 151553]). These changes resulted 
from reevaluation of the FEP list as outlined in The Enhanced Plan for Features, Events, and 
Processes (FEPs) at Yucca Mountain (BSC 2002 [DIRS 158966]) and KTI Letter Report, 
Response to Additional Information Needs on TSPAI 2.05 and TSPAI 2.06 (Freeze 2003 
[DIRS 165394]). Reorganization and redefinition of the DE FEPs between the Total System 
Performance Assessment for Site Recommendation (TSPA-SR) and TSPA-LA are more fully 
Preceding versions of this report include REV 00 (CRWMS M&O 2000 [DIRS 146681]) and 
REV 00 ICN 01 (CRWMS M&O 2000 [DIRS 151553]). REV 00 was originally issued based on 
9 December 2003 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
consideration of a repository with backfill and drip shields, as described in the License 
Application Design Selection Report (CRWMS M&O 1999, EDA II pp. 5-41 and 5-42 
[DIRS 102715]). REV 00 ICN 01 addressed a repository design without backfill and with 
changes to resolve certain thermal design issues, reorientation of the drift azimuths, and 
70,000-metric-ton of uranium (MTU) and 95,000 MTU designs (CRWMS M&O 2000 
[DIRS 150088] and CRWMS M&O 2000 [DIRS 149137]), which were not addressed in 
REV 00. 
1.1 PLANNING AND DOCUMENTATION 
Documentation requirements for this analysis report are described in the technical work plan 
(TWP), Development of Seismic Design Inputs, Preparation of a Seismic Topical Report, and 
Evaluation of Disruptive Events Features, Events, and Processes (BSC 2002 [DIRS 161737]). 
Detailed planning information and work scope for the seismic-related FEPs are provided in the 
TWP. Information and work scope for igneous-related FEPs are described in detail in the related 
TWP Igneous Activity Analyses for Disruptive Events (BSC 2003 [DIRS 164143]). The work 
described in the TWPs was based on the TSPA-SR DE FEP list. Changes in the assigned DE 
FEP list for the TSPA-LA resulted from the planned work scope and are further described in 
Table 6-1. 
1.2 SCOPE 
The scope of this report is to describe, evaluate, and document DE FEPs for the TSPA-LA. 
Activities for TSPA-LA FEPs were described in The Enhanced Plan for Features Events and 
Processes (FEPs) at Yucca Mountain (BSC 2002 [DIRS 158966]) and the KTI Letter Report 
Response to Additional Information Needs on TSPAI 2.05 and TSPAI 2.06 (Freeze 2003 
[DIRS 165394]). The results of the TSPA-LA FEP activities included FEP reorganization 
(eliminating Primary and Secondary FEP classification and eliminating redundant FEPs); 
changes in the level-of-detail of FEP descriptions; and reevaluation of FEP screening decisions, 
arguments, and TSPA dispositions. Changes from the FEP list used for the TSPA-SR evaluation 
include: revising the descriptions, deleting and reassigning FEPs, and creating and assigning 
new FEPs. The reorganization and reevaluation of the DE FEPs for TSPA-LA has resulted in a 
revised list of 20 DE FEPs, as extracted from the LA FEP list (DTN: MO0307SEPFEPS4.000 
[DIRS 164527]) and as modified during the review process for this analysis report. These 
revisions and changes are discussed in Section 6.1.1 and are summarized in Table 6-1. 
For a DE FEP that is Included in the TSPA-LA, this analysis report summarizes how the DE FEP 
is included and addressed in the TSPA-LA model, and cites the AMRs that fully provide the 
technical basis and detailed description of disposition of the DE FEP. For a DE FEP that is 
Excluded from the TSPA-LA, this analysis report identifies the basis for the screening decision 
(i.e., low probability, low consequence, or by regulation) and discusses the technical basis that 
supports that decision. In some cases, where an included or excluded DE FEP covers multiple 
technical areas and is shared with other FEP AMRs, this report may provide only a partial 
technical basis for the screening of the FEP. The full technical basis for these shared FEPs is 
addressed, collectively, by all of the sharing FEP AMRs. 
ANL-WIS-MD-000005 REV 01 10 December 2003 Features, Events and Processes: Disruptive Events 
In cases where a FEP covers multiple technical areas and is shared with other FEP AMRs, this 
analysis report provides only a partial technical basis for the screening decision as it relates to the 
initiating event. For those cases, the scope and intent of this FEP is only to define the probability 
of the event, describe the post-event conditions of the repository (e.g., in-drift conditions 
following an igneous intrusion), or quantify the event (e.g., amplitude of fault displacement or 
ground motion hazard). In some cases, a summary of the related information in sharing FEP 
AMRs is cited. The full technical basis for these shared FEPs is addressed, collectively, by all of 
the sharing FEP AMRs. Each DE FEP may, as indicated in parentheses in the list below, be 
shared with one or more of the analysis reports addressing the FEPs for the unsaturated zone 
(UZ), the saturated zone (SZ), the engineered barrier system (EBS), waste form, and the 
biosphere. The sharing FEP AMRs are listed in DTN: MO0307SEPFEPS4.000 [DIRS 164527]. 
The following list of 20 DE FEPs for TSPA-LA, and the sharing FEPs AMRs, results from the 
above-mentioned activities and includes: 
Seismic - Related FEPs: 
1.2.01.01.0A Tectonic activitylarge-scale (DE only) 
1.2.02.03.0A Fault displacement damages EBS components (DE, EBS) 
1.2.03.02.0A Seismic ground motion damages EBS components (DE, EBS) 
1.2.03.02.0B Seismic-induced rockfall damages EBS components (DE, EBS) 
1.2.03.02.0C Seismic-induced drift collapse damages EBS components (DE, EBS) 
1.2.03.02.0D Seismic-induced drift collapse alters in-drift thermohydrology (DE, EBS) 
1.2.03.03.0A Seismicity associated with igneous activity (DE only) 
1.2.10.01.0A Hydrologic response to seismic activity (DE, US, SZ) 
2.2.06.01.0A Seismic activity changes porosity and permeability of rock (DE, UZ, SZ) 
2.2.06.02.0A Seismic activity changes porosity and permeability of faults (DE, UZ, SZ) 
2.2.06.02.0B Seismic activity changes porosity and permeability of fractures (DE, UZ, SZ) 
2.2.06.03.0A Seismic activity alters perched water zones (DE, UZ) 
Igneous-Related FEPs: 
1.2.04.02.0A Igneous activity changes rock properties (DE, UZ, SZ) 
1.2.04.03.0A Igneous intrusion into repository (DE only) 
1.2.04.04.0A Igneous intrusion interacts with EBS components (DE, Waste Form) 
1.2.04.05.0A Magma or pyroclastic base surge transports waste (DE only) 
1.2.04.06.0A Eruptive conduit to surface intersects repository (DE only) 
1.2.04.07.0A Ashfall (DE, Biosphere) 
1.2.04.07.0C Ash redistribution via soil and sediment transport (DE only) 
1.2.10.02.0A Hydrologic response to igneous activity (DE, UZ, SZ) 
1.3 SCIENTIFIC ANALYSIS USE AND LIMITATIONS 
The intended use of this analysis report is to provide FEP screening information for a 
project-specific FEP database and to promote traceability and transparency for FEP dispositions. 
This report also is intended to be used as the source documentation and to provide the technical 
basis and supporting arguments for exclusion of DE FEPs from the TSPA-LA model. For shared 
FEPs, this report may provide only the DE-related portion of the technical basis. A short 
summary of the related discussions in other analysis reports is provided, as appropriate. For the 
DE FEPs that are designated for inclusion into the TSPA-LA model, the manner in which the 
ANL-WIS-MD-000005 REV 01 11 December 2003 Features, Events and Processes: Disruptive Events 
FEP has been included, the associated list of parameters, and any uncertainty considerations are 
provided in the cited analysis and model reports. 
The following limitations apply to this report: 
 Because this report cites supporting AMRs, the limitations inherently include any 
limitations or constraints described in the supporting AMRs. 
 In some cases where DE FEPs are shared, the scope of this analysis report is limited to 
providing only a quantification of the initiating DE (e.g., the amplitude of fault 
displacements and ground motions, or in some cases, probability of a given event or the 
resulting in-drift conditions). This is particularly germane for FEPs dealing with the 
response of the EBS components to fault displacement and ground motion. The 
discussion of the remainder of the technical basis is deferred to the technical AMRs, 
because analysis of the consequence for engineered features of the repository are better 
addressed by subject matter experts (SMEs) familiar with the performance of engineered 
components of the repository. 
 For screening purposes, this report generally uses mean values of probabilities, mean 
amplitude of events, or mean value of consequences as a basis for reaching a decision to 
include or exclude. Mean values are determined based on the range of possible values. 
 The results of the FEP screening presented herein 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 evaluation. 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 (66 FR 55732 [DIRS 156671]). (See also the 
requirements at 10 CFR 63.44 and 10 CFR 63.131 (66 Federal Register (FR) 55732 
[DIRS 156671]). 
ANL-WIS-MD-000005 REV 01 12 December 2003 Features, Events and Processes: Disruptive Events 
2. QUALITY ASSURANCE 
This work constitutes an analysis report that has been prepared according to AP-SIII.9Q, 
Scientific Analyses, and in accordance with related procedures and guidance documents as 
outlined in the TWP and Section 2 of this report. 
Development of this analysis report and the supporting analyses has been determined to be 
subject to the Office of Civilian Radioactive Waste Management (OCRWM) quality assurance 
(QA) program (BSC 2002, Section 8.3, Work Package ADEM06 [DIRS 161737]). Approved 
QA procedures identified in the TWP (BSC 2002, Section 4.3 [DIRS 161737]) have been used to 
conduct and document the activities described in this report. The TWP also identifies that no 
special controls beyond current work processes and procedures for the electronic management of 
data were applicable (BSC 2002, Section 8.3 [DIRS 161737]) during the analysis and 
documentation activities. 
The report contributes to the analysis and modeling used to support performance assessment. 
The DE FEPs documented herein have the potential to affect the performance of the natural 
barriers and various EBS components but do not themselves 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. 
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3. COMPUTER SOFTWARE AND MODEL USAGE 
This analysis report uses no computational software; therefore, the analysis is not subject to 
software controls. The analyses and arguments presented herein are based on guidance and 
regulatory requirements, results of analyses presented and documented in other analysis reports, 
or other technical literature. Software and models used in the supporting documents are cited, as 
appropriate, in this report for traceability and transparency purposes but were not used in its 
development. 
This analysis report was developed using only commercial off-the-shelf software (Microsoft 
Word 2000) for word processing, which is exempt from qualification requirements in accordance 
with AP-SI.1Q Software Management (Section 2.1). No additional applications (routines or 
macros) were developed using this commercial off-the-shelf software. 
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4. INPUTS 
The data, product output, technical information, and references used in this report were obtained 
from controlled source documents and other appropriate sources in accordance with the 
controlling procedure AP-3.15Q, Managing Technical Product Inputs. 
4.1 DIRECT INPUTS 
The procedure for managing inputs categorizes technical product inputs as either Direct Input or 
Reference Only. Direct Input constitutes the input used to address safety and waste isolation 
issues. Direct Input is further classified as Data-Qualified or as Other Direct Technical Product 
Input, which is further subdivided as Product Output, Technical Information, To Be Verified 
(TBV) data or factual information, Preliminary Technical Information (also denoted as TBV), 
Assumptions, or Software. 
No assumptions needing further confirmation are cited in this report. Software and models 
developed in the supporting documents are cited for traceability and transparency purposes; 
however, they were not used directly in development of the analyses and arguments presented 
herein. 
Data Description 
SeismicRelated FEPs 
Data Name 
Dip-steepening of 
lithologic units 
DTN / Data Source 
DTN: MO0310INPDEFEP.000 
[DIRS 165880] 
*Day et al. 1996, p. 2-7 
[DIRS 124302] 
No more than 20: based on Bow 
Ridge fault, faulted tuffs dip steeply to 
the east (20 to 30) into the graben(s) 
relative to the beds farther west in the 
unfaulted areas (8 to 15) 
About 25 
4.1.1 Data-Qualified and Factual Information 
This section identifies qualified data and other factual information used to justify exclusion of 
DE FEPs. The governing procedure, AP-3.15Q , defines qualified data. Table 4-1 lists qualified 
data and includes data and information developed for or by the Project, which are statused as to 
be verified (TBV). The TBV information is noted in Table 4-1 with an asterisk. In these cases, 
the factual information comprises site characterization samples and values that were collected 
prior to QA program implementation or collected by other entities that may or may not have had 
an approved QA program. Table 4-1 lists all Document Tracking Numbers (DTN) cited to 
justify the FEP exclusion regardless of qualification status. 
Table 4-1. Data-Qualified and Factual Information Used for DE FEP Exclusion 
Analysis 
Report 
Section 
6.2.1.1 
Critical angle of 
tilting 
DTN: MO0310INPDEFEP.000 
[DIRS 165880] 
*Fridrich et al. 1996, pp. 2-21 and 
2-22 [DIRS 105086] 
About 60 km Source depth of 
basaltic magma 
DTN: MO0310INPDEFEP.000 
[DIRS 165880] 
*Crowe et al. 1995, pp. 5-2, 5-5, and 
Figure 5.1 [DIRS 100110] 
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Table 4-1. Data-Qualified and Factual Information Used for DE FEP Exclusion (Continued) 
Analysis 
Report 
Section 
6.2.1.8 
6.2.1.10, 
6.2.1.11 
6.2.1.11 
6.2.2.1 
ANL-WIS-MD-000005 REV 01 18 December 2003 
Data Name 
Water level rise at 
Yucca Mountain 
due to 
earthquakes 
Water level rise 
due to seismic 
pumping 
Results of the 
Yucca Mountain 
Probabilistic 
Seismic Hazard 
Analysis (PSHA) 
Results of the 
Yucca Mountain 
Probabilistic 
Seismic Hazard 
Analysis (PSHA) 
Field observations 
for intruded dikes 
at Paiute Ridge 
Width of zone of 
alteration around 
intruding dikes 
Data Description 
SeismicRelated FEPs (continued) 
Fluctuations range from 90 cm related 
to a 7.5 magnitude earthquake near 
Landers, CA, to 20 cm for a second 
quake of 6.6 magnitude near Big Bear 
Lake, CA. 
Results of evaluation indicate at most a 
rise of a few tens of meters 
Mean displacement in intact rock: less 
than 0.1 cm for a 10-8 
annual-exceedance probability 
Mean value for displacement along the 
Solitario Canyon fault of 10 m 
Mean displacement on existing 
fractures: less than 1 cm for a 10-8 
annual-exceedance probability 
Igneous-Related FEPs 
Fused wall rock extends only 20-100 
cm into the wall rock. Cooling joints 
extend 10-20 cm into the wall rock. 
Evidence of interaction with faults. 
Presence of platy texture along margin 
of dike, and vesicles in the welded tuff. 
Limited to a few meters to a few 
hundred meters for observed dikes. 
Analogue site at Nevada Test Site 
indicates less than 10 m. 
DTN / Data Source 
DTN: MO0310INPDEFEP.000 
[DIRS 165880] 
*OBrien 1993 [DIRS 101276] 
DTN: MO0310INPDEFEP.000 
[DIRS 165880] 
*National Research Council 1992 
[DIRS 105162] 
DTN: MO0004MWDRIFM3.002 
[DIRS 149092] 
CRWMS M&O 1998, p. 8-7 and 
Figure 8.3 [DIRS 103731] 
Mean displacements at selected 
points taken from files: 
./displ/tot_haz/s7d.frac_mean.gz 
./displ/tot_haz/s8d.frac_mean.gz 
DTN: MO0004MWDRIFM3.002 
[DIRS 149092] 
CRWMS M&O 1998, Figures 8.10 
and 8.13 [DIRS 103731] 
Mean displacements at selected 
points taken from files: 
./displ/tot_haz/s7c.frac_mean.gz 
./displ/tot_haz/s8c.frac_mean.gz 
DTN: MO0310INPDEFEP.000 
[DIRS 165880] 
*Carter-Krogh and Valentine (1996, 
pp. 7 and 8 [DIRS 160928]) 
DTN: MO0310INPDEFEP.000 
[DIRS 165880] 
*CRWMS M&O 1998, pp. 5-41, 5-42, 
5-57, 5-71 and 5-72 [DIRS 105347] Features, Events and Processes: Disruptive Events 
Table 4-1. Data-Qualified and Factual Information Used for DE FEP Exclusion (Continued) 
Limited to between a few meters to a 
few hundred meters for observed dikes. [DIRS 165880] 
Analogue site at Nevada Test Site 
indicates less than 10 m. 
DTN / Data Soure 
DTN: MO0310INPDEFEP.000 
[DIRS 165880] 
*Crowe et al. (1986, p. 32-34 
[DIRS 101532]) 
DTN: MO0310INPDEFEP.000 
[DIRS 165880] 
*Crowe et al. (1986,Figure 19 
[DIRS 101532]) 
DTN MO0002SPATOP00.001 
[DIRS 152643] 
(for grid node coordinates shown) 
DTN: MO0310INPDEFEP.000 
[DIRS 165880] 
*Carter-Krogh and Valentine (1996, 
pp. 7 and 8 [DIRS 160928] 
DTN: MO0310INPDEFEP.000 
*CRWMS M&O 1998, pp. 5-1, 5-2, 
5-41, 5-42, 5-57 5-71, and 5-72 
[DIRS 105347] 
DTN: MO0310INPDEFEP.000 
[DIRS 165880] 
*CRWMS M&O 1998, p. 5-57 
[DIRS 105347] 
DTN: MO0310INPDEFEP.000 
[DIRS 165880] 
*Flint and Flint 1995 [DIRS 100394] 
Data Description 
Igneous-Related FEPs (continued) 
Base surge deposits at Lathrop Wells 
Cone extend no more than 1 km. 
Relative frequency Mean value of 91 m and maximum 
of crater depths depth of 365 m. Crater depths greater 
for known than 215 m occur approximately 15 
hydrovolcanic percent of the time. 
craters. 
Coordinates and elevations selected 
included 
Northing Easting Elevations: 
775,000 565,500 1262 m 
771,300 564,100 1267 m 
769,300 563,500 1283 m 
Fused wall rock extends only 20-100 
cm into the wall rock. Cooling joints 
extend 10-20 cm into the wall rock. 
Evidence of interaction with faults. 
Presence of platy texture along margin 
of dike, and vesicles in the welded tuff. 
Analogue site indicates thermal transfer 
to surrounding rock is minimal. 
Soils exceeding 6 m thickness eliminate 
the infiltration of water to the 
soil/bedrock contact except in channels. 
Data Name 
Extent of base 
surge deposits 
Topographic 
elevations at 
select points in the 
eastern part of the 
repository 
Field observations 
for intruded dikes 
at Paiute Ridge 
Width of zone of 
alteration around 
intruding dikes 
Potential for 
development of 
hydrothermal 
systems 
Influence of soil 
thickness on 
infiltration 
Analysis 
Report 
Section 
6.2.2.4 
6.2.2.8 
Note: Citations marked with an * were classified as TBV as part of DTN MO0310INPDEFEP.000 [DIRS 165880] 
per the governing procedure. In accordance with AP-3.15Q, data that need to be verified comprise factual 
information comprising site characterization samples and values that were collected prior to QA program 
implementation or collected by other entities that do not or did not have an approved QA program. If the 
data cannot be verified it will be qualified or replaced as part of the data confirmation process. 
ANL-WIS-MD-000005 REV 01 19 December 2003 Features, Events and Processes: Disruptive Events 
4.1.2 Product Outputs 
Where possible, other direct input has been obtained from controlled source documents (product 
output) using the appropriate document identifiers or records system accession numbers. 
Sources include, but are not limited, to YMP-prepared databases, drawings, and other technical 
documents. 
TSPA-LA 
FEP Number 
4.1.2.1 YMP FEP Database and Included FEPs 
The FEP list used for the TSPA-LA screening documented in this report was extracted from 
DTN: MO0307SEPFEPS4.000 [DIRS 164527]. The list of FEPs was reviewed for possible DE 
FEPs and evaluated for appropriateness of use and comprehensiveness and was determined to be 
comparable and traceable to the list of DE FEPs presented for site recommendation (SR) and 
suitable for use as a preliminary list of DE FEPs to be further evaluated for the LA. 
Modifications to the DE FEP list for the LA are detailed in Section 6.1.1. 
The process- and model-level AMRs provide a list of included FEPs and discuss the technical 
basis for inclusion. The list of included FEPs is taken from supporting AMRs and is considered 
as direct input for this report. Table 4-2 lists the included FEPs and the source AMRs wherein 
the technical basis for including the FEP is discussed. However, the technical basis for inclusion 
given in the supporting AMRs and cited in the FEP discussions in Section 6.2 is considered as 
reference only material within the context of this report. Furthermore, data sets developed in 
those process- and model-level AMRs are referenced for transparency; unless the numeric values 
are used directly in a calculation or screening decision in this report, the data sets are not 
considered as direct input and are not addressed in this section. The supporting AMRs for 
included FEPs are discussed briefly in Section 6.1.3. Tables 6-2 and 6-3 list the documents that 
include DE FEPs and describe the DE-related conceptual models included in TSPA-LA. 
Table 4-2. Included DE FEPs and Supporting AMRs 
Analysis 
Report 
Section 
TSPA-LA FEP Name 
Seismic-Related FEPs 
Supporting AMR Documentation 
BSC 2003, Table 4 [DIRS 161812] 6.2.1.2 1.2.02.03.0A Fault displacement damages EBS 
components 
BSC 2003, Table 4 [DIRS 161812] 6.2.1.3 1.2.03.02.0A Seismic ground motion damages EBS 
components 
6.2.1.4 1.2.03.02.0B Seismic-induced rockfall damages BSC 2003, Table 4 [DIRS 161812] EBS components 
6.2.1.6 1.2.03.02.0D Seismic-induced drift collapse alters 
in-drift thermohydrology 
This FEP is derived from 2.1.07.02.0A 
Drift Collapse, see Table 6-1 of this 
report for additional clarification. 
Supporting documentation for this new 
FEP is taken from BSC 2003, Table 4 
[DIRS 161812] from FEP 1.2.03.02.0D. 
BSC 2003, Table 6.4.2 [DIRS 166274] 6.2.1.7 1.2.03.03.0A Seismicity associated with igneous 
activity 
ANL-WIS-MD-000005 REV 01 20 December 2003 Features, Events and Processes: Disruptive Events 
Analysis 
Report 
Section 
6.2.2.2 1.2.04.03.0A 
6.2.2.3 1.2.04.04.0A Igneous intrusion interacts with EBS 
components 
6.2.2.5 1.2.04.06.0A Eruptive conduit to surface intersects 
repository 
6.2.2.6 1.2.04.07.0A Ashfall 
6.2.2.7 1.2.04.07.0C Ash redistribution via soil and 
4.1.2.2 
Information exchange drawings (IEDs) or design documents used to provide technical 
information for DE FEP exclusion include those shown in Table 4-3. 
Analysis 
Report Section 
6.2.2.4 
Table 4-3. Drawings and Design Documents Used as Basis for DE FEP Exclusion 
Type of Information 
Elevation of drift ends 
in the eastern 
repository 
Approximate drift end 
coordinates (ft) from 
State Plane 
Coordinate grid 
Value 
Seismic-Related FEPs 
(None Used) 
Igneous-Related FEPs 
Maximum of Elevation of Drifts 
Within Block 2E 
1042 m for Drift 2-1E 
1055 m for Drift 2-12E 
1063 m for Drift 2-19E 
Drift Northing Easting 
2-1E 775,000 565,500 
2-12E 771,300 564,100 
2-19E 769,300 563,500 
IED Reference 
800-IED-EBSO-00402-000-00B 
[DIRS 161727] 
800-IED-EBSO-00401-000-00C 
[DIRS 162289] 
Information Exchange Drawings 
ANL-WIS-MD-000005 REV 01 21 December 2003 
Table 4-2. Included DE FEPs and Supporting AMRs (Continued) 
TSPA-LA 
FEP Number 
Igneous intrusion into repository 
sediment transport 
TSPA-LA FEP Name 
Igneous-Related FEPs 
Supporting AMR Documentation 
BSC 2003, Table 9 [DIRS 163769]; 
BSC 2003, Table 5 [DIRS 161838]; 
BSC 2003, Table 4 [DIRS 165923] 
BSC 2003 Table 5 [DIRS 161838]; 
BSC 2003 Table 4 [DIRS 165923]; 
BSC 2003, Table 3 [DIRS 161851]; 
BSC 2003, Table 6-1 [DIRS 165002] 
BSC 2003 Table 5 [DIRS 161838]; 
BSC 2003 Table 3 [DIRS 161851]; 
BSC 2003, Table 6 [DIRS 161840] 
BSC 2003 Table 5 [DIRS 161838]; 
BSC 2003, Table 6 [DIRS 161840] 
BSC 2003 Table 5 [DIRS 161838] Features, Events and Processes: Disruptive Events 
4.1.2.3 Product Output and Preliminary Technical Information Used for DE FEP 
Exclusion 
Table 4-4 lists product output from supporting AMRs that is specifically cited to exclude DE 
FEPs. 
Analysis 
Report 
Section 
6.2.1.1 
6.2.1.1, 
6.2.1.2 
6.2.1.5 
6.2.1.9 
6.2.1.1, 
6.2.1.8, 
6.2.1.9, 
6.2.1.10 
6.2.1.11 
6.2.1.11 
6.2.1.12 
6.2.2.1 
6.2.2.4 
Table 4-4. Specific Product Output Used for DE FEP Exclusion 
Value 
SeismicRelated FEPs 
Low to moderate rate, with low to 
moderate historical seismicity. 
Experiencing declining strain rates. 
12.7 to 11.6 million years ago 
0.0010.03 mm/yr 
46 blocks with total volume of 50.6 
m3, and maximum block size of 
7.63 m3 for 10-7 ground motions in 
non-lithophysal zone. 
Collapse is total at 106 ground 
motions 
Overestimation is conservative 
Method of inclusion of fractures Conceptual approach 
Results of sensitivity analysis 
Low to moderate rate, with low to 
moderate historical seismicity. 
Experiencing declining strain rates. 
Perched water zone calculation Volume of water in fracture space 
IgneousRelated FEPs 
Centers around N30E, and highest 
probabilities for azimuths of 
between 20 and 40 degrees 
Results of sensitivity analysis 
Basalt flows extend no more than 1 
km from the scoria cone 
Surface topography contours 
above the repository 
Type of Input 
Extensional strain rate for Basin 
and Range and relative 
seismicity 
Time of peak tectonism 
Local fault slip rates 
Volume and number of blocks 
for seismic-induced drift 
collapse in non-lithophysal 
zone. 
Seismic-induced collapse of 
lithophysal zone 
Flowing interval spacing in SZ 
Sensitivity analysis for change 
in fracture aperture 
Extensional strain rate for Basin 
and Range and relative 
seismicity 
Most commonly assigned dike 
orientation and highest 
probabilities of dike orientation. 
Sensitivity analysis for change 
in fracture aperture. 
Direction of maximum 
transmissivity for horizontal 
anisotropy 
Extent of lava flows and other 
surface flow related volcanic 
deposits 
Depth of Repository below 
surface 
of perched water zone compared to [DIRS 164873 ] 
annual flux 
The direction of maximum 
transmissivity may be about N 15 E [DIRS 164870] 
Data Source 
CRWMS M&O 2000, Section 
6.3.2 [DIRS 142321] 
CRWMS M&O 2000, Table 6 
[DIRS 142321] 
BSC 2003, Tables 31 and 33 
[DIRS 162711] 
BSC 2003, Section 6.4.1.1 
[DIRS 162711] 
BSC 2001, Section 1 
[DIRS 156965] 
BSC 2003, Section 6.2.5 
[DIRS 164870] 
CRWMS M&O 2000, 
Section 7 [DIRS 151953] 
CRWMS M&O 2000, 
Section 6.3.2 [DIRS 142321] 
BSC 2003 Attachment I 
BSC 2003, Section 6.3.2 and 
Table 18 [DIRS 163769] 
CRWMS M&O 2000, 
Section 7 [DIRS 151953] 
BSC 2003, Section 6.2.5.10 
BSC 2003, Section 6.2 
[DIRS 163769] 
BSC2002, Figure 1 
[DIRS 159124] 
ANL-WIS-MD-000005 REV 01 22 December 2003 Features, Events and Processes: Disruptive Events 
Table 4-4. Specific Product Output Used for DE FEP Exclusion (Continued) 
Type of Input Value 
IgneousRelated FEPs (continued) 
Data Source 
BSC 2003, Section 6.3.2 and 
Table 18 [DIRS 163769] 
Centers around N30E, and highest 
probabilities for azimuths of 
between 20 and 40 degrees 
Most commonly assigned dike 
orientation and highest 
probabilities of dike orientation. 
Results of sensitivity analysis CRWMS M&O 2000, 
Section 7 [DIRS 151953] 
Sensitivity analysis for change 
in fracture aperture. 
Analysis 
Report 
Section 
6.2.2.8 
BSC 2003, Section 6.2.5.10 
[DIRS 164870] 
The direction of maximum 
transmissivity is about N15E 
Direction of maximum 
transmissivity for horizontal 
anisotropy 
USGS 2001, Section 6.1.2 
[DIRS 160355] 
Thicker soils tend to decrease 
infiltration 
Relation of soil thickness to 
infiltration rates 
4.1.3 Other Technical Information 
For this report, other technical information consists of CFR citations and non-YMP specific 
technical journal articles. 
4.1.3.1 Regulations that Provide Direct Input for FEP Screening 
The nature of the FEP screening arguments and TSPA dispositions is such that the NRC 
regulations (and the corresponding and incorporated portions of 40 CFR 197) serve as direct 
inputs for determining whether a FEP can be excluded from further considerations. 
Regulatory Basis for Screening FEPs on Low ProbabilityThe application of the 
low-probability threshold for FEP screening is further described in Section 6.1.2. For 
probability, the direct input is expressed as: 
10 CFR 63.114(d) 
(66 FR 55732 [DIRS 156671]). 
One chance in 10,000 of occurring 
over 10,000 years 
The EPA provides essentially the same criterion in 40 CFR 197.36 (66 FR 32074 
[DIRS 155216]): 
The DOEs performance assessments should not include consideration of very 
unlikely features, events, or processes, i.e., those that are estimated to have less 
than one chance in 10,000 of occurring within 10,000 years of disposal. The 
NRC shall exclude unlikely features, events, and processes, or sequence of 
processes from the assessments for the human intrusion and ground water 
protection standards. The specific probability of the unlikely features, events, and 
processes is to be specified by NRC. 
The low-probability criterion is stated as less than one chance in 10,000 of occurring in 
10,000 years (10-4/104 yr). As explained in Assumption 5.1, this is assumed equivalent to a 10-8 
annual-exceedance probability. 
ANL-WIS-MD-000005 REV 01 23 December 2003 Features, Events and Processes: Disruptive Events 
Regulatory Basis for Screening FEPs on Low ConsequenceThe application of the 
low-consequence arguments for FEP screening is described further in Section 6.1.2 of this report. 
For low consequence, the direct input is expressed as: 
10 CFR 63.114 (e and f) 
(66 FR 55732 [DIRS 156671]). 
Would be significantly changed 
by its omission 
The terms significantly changed and changed significantly are undefined terms in the NRC 
and EPA regulations. The absence of significant change, or an insignificant change, if the FEP is 
omitted, is inferred for FEP-screening purposes to be equivalent to having no effect or negligible 
effect. 
The low-consequence criteria described in 10 CFR 63.114(e and f) (66 FR 55732 
[DIRS 156671]), are provided as follows: 
Provide the technical basis for either inclusion or exclusion of specific features, 
events, and processes in the performance assessment. Specific features, events, 
and processes must be evaluated in detail if the magnitude and time of the 
resulting radiological exposures to the reasonably maximally exposed individual, 
or radionuclide releases to the accessible environment, would be significantly 
changed by their omission. 
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. 
The EPA provides essentially the same criteria for low consequence at 40 CFR 197.36 
(66 FR 32074 [DIRS 155216]): 
In addition, unless specified in NRC regulations, the DOEs performance 
assessments need not evaluate the impacts resulting from any features, events and 
processes or sequences of events or processes with a higher chance of occurrence 
if the results of the performance assessments would not be changed significantly. 
In addition to the regulatory FEP screening criteria, the characteristics, definitions, and concepts 
given in the regulations also provide direct input for screening the DE FEPs by regulation. 
Regulatory Basis for Screening FEPs By RegulationRegulations also address required 
characteristics, definitions, and concepts, which may serve as the basis for exclusion of FEPs by 
regulation, as further discussed in Section 4.2. Because the regulatory concepts and definitions 
ANL-WIS-MD-000005 REV 01 24 December 2003 Features, Events and Processes: Disruptive Events 
are used as part of the technical basis for an exclude decision, the relevant regulatory cites are 
listed and addressed as direct input and listed in Table 4-5. 
By specifying characteristics, concepts, and definitions, the regulations serve as de facto inputs 
used for screening related FEPs. For the DE FEPs, these criteria include the characteristics, 
concepts, and definitions pertaining to the reference biosphere, the geologic setting, and the 
RMEI. Also pertinent are characteristics, concepts, and definitions that must be considered 
during the FEP screening, such as the areal extent of the accessible environment and of the 
controlled area, and the spatial relationship to the distance from the repository to the RMEI. 
These terms define or imply geographical limits or constrain the consideration of the future state 
of the reference biosphere and/or geologic setting. 
Table 4-5. Direct Input from Regulations Used for DE FEP Exclusion 
Value 
Igneous-Related FEPs 
Type of Input 
Location of the RMEI Within the accessible environment 
Data Source 
10 CFR 63.312 (a, b, c, d, e) 
(66 FR 55732 [DIRS 156671]) 
10 CFR 63.302 
(66 FR 55732 [DIRS 156671]). 
Analysis 
Report 
Section 
6.2.2.4 
Definition of the 
accessible 
environment and limit 
of controlled area 
No closer than 18 km to the south in 
direction of groundwater flow and 
over a contaminated groundwater 
plume 
No greater than 5 km in any direction 
other than direction of groundwater 
flow 
10 CFR 63.305 (b and c) 
(66 FR 55732 [DIRS 156671]) 
DOE should not project changes to 
the biosphere or than climate 
Characteristics of 
reference biosphere 
6.2.2.8 10 CFR 63.2 
(66 FR 55732 [DIRS 156671]) 
DOE must vary factors related to 
geology, hydrology and climate 
Definition of reference 
biosphere 
Definition specifically includes 
topography and soils 
Lives in the accessible environment above the highest concentration of 
radionuclides in the plume of contamination. 
Accessible environment means any location outside the controlled area. 
Reasonably Maximum Exposed IndividualThe characteristics of the RMEI to be used in 
exposure calculations are given at 10 CFR 63.312 (a, b, c, d, and e) (66 FR 55732 
[DIRS 156671], and also at 40 CFR 197.21(a, b, and c) (66 FR 32074 [DIRS 155216])). 
Pertinent to the DE FEPs is the criterion in 10 CFR 63.312(a) (66 FR 55732 [DIRS 156671]) that 
the RMEI: 
For the DE FEPs, the distance from the repository to the receptor is a criterion of primary 
interest. From 10 CFR 63.302 (66 FR 55732 [DIRS 156671] and also at 40 CFR 197.12 
(66 FR 32074 [DIRS 155216])): 
ANL-WIS-MD-000005 REV 01 25 December 2003 Features, Events and Processes: Disruptive Events 
Moreover, the controlled area is: 
(1) The surface area identified by passive institutional controls that encompasses no more 
than 300 square kilometers. It must not extend farther: 
i. South than 36 40 13.6661 north latitude, in the predominant direction of ground 
water flow; and 
ii. Than five kilometers from the potential repository footprint in any other direction; 
and 
(2) The subsurface underlying the surface area. 
The preamble in the regulations for 40 CFR 197 (66 FR 32074, p. 32117 [DIRS 155216]) states 
further that: 
If fully employed by DOE, and based on current repository design, the controlled 
area could extend approximately 18 km in the direction of ground water flow 
(presently believed to be in a southerly direction) and extend no more than 5 km 
from the repository footprint in any other direction. 
Furthermore, the NRC states in the preamble to 10 CFR Part 63 (66 FR 55732, p. 55753 
[DIRS 156671]) that: 
At distances less than 18 km to the Yucca Mountain site, there is evidence of 
intermittent or temporary occupation in modern (historic) times in and around the 
sitefor prospecting or ranching.  There also are a number of Native American 
archeological sites reported throughout NTS closer to the site than the Lathrop 
Wells location. However, the literature indicates that these were never 
permanently occupied, and most were abandoned by the end of the 1800s. 
Overall, the literature suggests many reasons for the absence of permanent 
inhabitation at distances much closer than 18 km to the site - unfavorable 
agricultural conditions, inhospitable terrain, the scarcity of mineral resources, and 
limitations on water availability. 
These concepts are pertinent because the distance from the repository is of primary interest in 
evaluating potential exposure risk from igneous-related releases. These definitions and concepts 
indicate that the RMEI is located no closer than 18 km to the south in the direction of 
groundwater flow and over a contaminated groundwater plume (in accordance with 
10 CFR 63.312 (a, b, c, d, and e) 66 FR 55732 [DIRS 156671]), and that the limit of the 
controlled area is no greater than 5 km from the repository in any other direction (as specified at 
10 CFR 63.302 66 FR 55732 [DIRS 156671]). The location and characteristics of the RMEI for 
the nominal scenario also are used for the disruptive scenario. The location of the RMEI is also 
of importance for determining exposure and is part of the technical basis for included FEPs. 
Reference Biosphere and Geologic SettingCPer 10 CFR 63.2 (66 FR 55732 [DIRS 156671]), 
the reference biosphere is defined as: 
ANL-WIS-MD-000005 REV 01 26 December 2003 Features, Events and Processes: Disruptive Events 
Reference biosphere means the description of the environment inhabited by the 
reasonably maximally exposed individual. The reference biosphere comprises the 
set of specific biotic and abiotic characteristics of the environment, including, but 
not necessarily limited to, climate, topography, soils, flora, fauna, and human 
activities. 
Characteristics pertaining to the reference biosphere are presented in 10 CFR 63.305(a) and 
(b) (66 FR 55732 [DIRS 156671]). 
(a) Features, events, and processes that describe the reference biosphere must be 
consistent with present knowledge of the conditions in the region surrounding the 
Yucca Mountain site. 
(b) DOE should not project changes in society, the biosphere (other than climate), human 
biology, and increase or decreases of human knowledge or technology. In all analyses 
done to demonstrate compliance with this part, DOE must assume that all those factors 
remain constant as they are at the time of license application. 
The evolution of the reference biosphere and the geologic setting are linked by the NRC at 
10 CFR 63.305(c) ((66 FR 5732 [DIRS 156671]; also by the EPA at 40 CFR 197.15 
(66 FR 32074 [DIRS 155216])). 
(c) DOE must vary factors relating to the geology, hydrology, and climate, based upon 
cautious, but reasonable assumptions, consistent with present knowledge of factors 
that could affect the Yucca Mountain disposal system in the next 10,000 years. 
The EPA language varies slightly by stating reasonable assumptions of the changes in these 
factors; in contrast, the NRC states consistent with present knowledge of factors. Per 
10 CFR 63.2 (66 FR 55732 [DIRS 156671]), the geologic setting is defined as: 
The geologic, hydrologic, and geochemical systems of the region in which a 
geologic repository is or may be located. 
It is inferred from 10 CFR 63.114(a) that the evolution of the geologic setting is to be based on 
data related to Yucca Mountain and the surrounding regions, inclusive of disruptive process and 
events. Although not specifically defined in 10 CFR Part 63, as applied to the geologic setting 
and for purposes of this report, disruptive events is inferred to mean seismic- and 
igneous-related events and processes. Other YMP project documents also list criticality and 
human intrusion as disruptive events. FEPs relevant to those considerations are beyond the 
scope of this document and are addressed separately. 
By NRCs juxtaposition of the geologic and hydrologic factors within the subsection that is 
addressing the required characteristics of the reference biosphere, it is inferred that the listed 
regulatory constraint of changes in the reference biosphere also may be applicable to conditions 
that may occur at Yucca Mountain. In particular, it is inferred that changes in the biosphere 
(other than climate) that result from geologic disruptive events should not be projected. Changes 
to soil, topography, and flora are specifically identified in the definition of the referenced 
ANL-WIS-MD-000005 REV 01 27 December 2003 Features, Events and Processes: Disruptive Events 
biosphere. This has particular application for FEPs related to changes triggered by an eruptive 
igneous event. Such an event has the potential to change or influence soil characteristics 
(e.g., water retention characteristics rates and distribution of percolation); alter the topography 
(e.g., changes to hillside slopes, creation of lava flows and volcanic cones, changes in drainage 
patterns, drainages clogging with eroding ash, drainages damming); and alter the surrounding 
flora. Seismic events also have the potential for altering topography. The application of this 
regulatory input with regard to changes in topography and soils stemming from an eruptive 
event, and more-restrictive alternative interpretations, are further discussed in Section 6.2.2.8. 
Consequently, the required characteristics of the reference biosphere as defined by the 
regulations are considered as direct input for an exclusion argument, because constraint on 
changes to the reference biosphere contributes to, but does not constitute, the technical basis for 
exclusion of FEP 1.2.04.07.0C (Ash redistribution via soil and sediment transport). 
4.1.3.2 Other Technical Information 
No other technical information is cited as a direct input to the technical basis for excluding DE 
FEPs. Other corroborating citations are used as reference only material. 
Relationship of EPA and NRC Regulations to the PRD and the 
Acceptance Criteria from YMRP 
4.2 CRITERIA 
This section addresses the various criteria relevant to the FEP screening process. These criteria 
stem from the applicable regulations at 10 CFR Part 63 (and also those incorporated from 
40 CFR Part 197), as identified in the Project Requirements Document (PRD) (Canori and 
Leitner 2003 [DIRS 161770]). These criteria find expression as specific acceptance criteria 
presented by the NRC in the YMRP (NRC 2003 [DIRS 163274]). The correlation of the various 
regulations and criteria are listed in Table 4-6, and applications of the criteria for FEP screening 
are described in Section 4.1.3.1 of this report. 
Table 4-6. 
10 CFR Part 63 40 CFR Part 
197 
Associated 
PRD 
[DIRS 161770] 
Regulatory 
Citation 
[DIRS 156671] 
Description of the Applicable 
Regulatory Requirement or 
Acceptance Criteria 
Regulatory 
Citation 
[DIRS 155216] 
General Requirements and Scope Pertinent to FEP Screening 
63.114(a). Not Applicable 
PRD-002/ 
T-015 
Associated YMRP 
Criteria 
[DIRS 163274] 
2.2.1.2.1.3 
Acceptance 
Criterion 1 
Include data related to geology, 
hydrology, geochemistry, and 
geophysics 
63.114(a) Not Applicable 
PRD-002/ 
T-015 
2.2.1.2.1.3 
Acceptance 
Criterion 1 
Include information of the design of 
the engineered barrier system used 
to define parameters and 
conceptual models 
197.14 63.114(b) 
PRD-002/ 
T-015 
2.2.1.2.2.3 
Acceptance 
Criteria 1 through 5 
Account for uncertainties and 
variabilities in parameter values 
and provide the technical basis for 
parameter ranges, probability 
distributions, or bounding values 
ANL-WIS-MD-000005 REV 01 28 December 2003 Features, Events and Processes: Disruptive Events 
Table 4-6. Relationship of EPA and NRC Regulations to the PRD and the 
Acceptance Criteria from YMRP (Continued) 
10 CFR Part 63 40 CFR Part 
197 
Associated 
PRD 
Regulatory 
Citation 
Regulatory 
Citation 
[DIRS 156671] [DIRS 155216] 
FEP Screening Criteria 
63.114 (a) Not Applicable 
Description of the Applicable 
Regulatory Requirement or 
Acceptance Criteria 
Consider disruptive events, 
(specifically volcanism and 
seismicity) 
[DIRS 161770] 
PRD-002/T- 
015 
Not Applicable Not Applicable Not Applicable 
Provide justification and technical 
basis for excluding features, 
events, and processes specifically 
excluded by regulation 
Associated YMRP 
Criteria 
[DIRS 163274] 
2.2.1.2.1.3 
Acceptance 
Criterion 1 
2.2.1.2.1.3 
Acceptance 
Criterion 2 
2.2.1.2.1.3 
Acceptance 
Criterion 2 
PRD-002/ 
T-015 
63.114(d) 
197.36 
63.342 PRD-002/ 
T-034 
Provide technical basis for either 
inclusion or exclusion of features, 
events, and processes. Provide 
justification and technical basis for 
those excluded based on 
probability 
2.2.1.2.2.3 
Acceptance 
Criteria 1 through 5 
PRD-002/ 
T-015 
63.114 
(e and f) 
2.2.1.2.1.3 
Acceptance 
Criterion 2 
197.36 
63.342 PRD-002/ 
T-034 
2.2.1.2.2.3 
Acceptance 
Criteria 1 and 2 
Provide technical basis for either 
inclusion or exclusion of features, 
events. Provide justification and 
technical basis for those excluded 
based on lack of significant change 
in resulting radiological exposure or 
release to the accessible 
environment 
The PRD (Canori and Leitner 2003 [DIRS 161770]) documents and categorizes the regulatory 
requirements and other project requirements, and provides a crosswalk to the various YMRP 
subprojects that are responsible for ensuring that the criteria have been satisfied 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 4-6 
provides a crosswalk between the regulatory requirements, the PRD (Canori and Leitner 2003 
[DIRS 161770]), and the acceptance criteria provided in the YMRP (NRC 2003, Sections 2.2.1.2 
[DIRS 163274]). 
The NRC will be reviewing the LA. The basis of the review is described in the YMRP 
(NRC 2003, Sections 2.2.1.2 [DIRS 163274]) and the bases for acceptance are stated as 
acceptance criteria. Table 4-6 correlates the acceptance criteria to the corresponding regulations 
and related PRDs as they pertain to FEP-related criteria. With only a few exceptions, the 
regulatory requirements at 40 CFR Part 197 (66 FR 32074 [DIRS 155216]) have been 
incorporated within the requirements of 10 CFR Part 63 (66 FR 55732 [DIRS 156671]). 
However, because the EPA regulations at 40 CFR Part 197 have not been superceded, this report 
has for completeness sake, retained cites in the individual FEP discussions. In a few instances, 
differences in the regulations are also cited to clarify a particular FEP concept, definition, or 
approach to a screening argument. 
ANL-WIS-MD-000005 REV 01 29 December 2003 Features, Events and Processes: Disruptive Events 
The cited YMRP criteria are provided in Table 4-7. The Acceptance Criteria for FEP screening 
presented in the YMRP echo the screening criteria of low probability and low consequence 
(NRC 2003 Section 2.2.1.2.1.3 Acceptance Criterion 2 Screening of the Initial List of Features, 
Events, and Processes Is Appropriate [DIRS 163274]), but also allow for exclusion of a FEP if 
the process is specifically excluded by the regulations. To wit: 
The U.S. Department of Energy has justified excluding each feature, event, and 
process. An acceptable justification for excluding features, events, and processes 
is that either the feature, event, and process is specifically excluded by regulation; 
probability of the feature, event, and process (generally an event) falls below the 
regulatory criterion; or omission of the feature, event, and process does not 
significantly change the magnitude and time of the resulting radiological 
exposures to the reasonably maximally exposed individual, or radionuclide 
releases to the accessible environment. 
The application of the FEP screening criteria is described further in Section 6.1.2. The 
regulatory criteria for determining low probability, determining low consequence, and the 
characteristics, definitions, and concepts used to screen on the basis of regulation are listed in 
Section 4.1.3.1 as Direct Input. 
4.3 CODES AND STANDARDS 
Applicable codes and standards include 10 CFR Part 63 (66 FR 55732 [DIRS 156671]). As 
applicable for FEP evaluation, portions of the NRC regulations (and the corresponding portions 
of the EPA regulation at 40 Part 197 that have been incorporated into the NRC regulations) may 
serve as direct input and/or criterion. Regulations used as direct input, including the criterion 
used for FEP screening, are cited in Section 4.1.3.1, and those providing criteria as identified in 
the PRD are cited in Section 4.2. 
ANL-WIS-MD-000005 REV 01 30 December 2003 Table 4-7. YMRP Criteria and the DE FEPs AMR. 
Features, Events and Processes: Disruptive Events 
ANL-WIS-MD-000005 REV 01 31 
How Addressed in this Analysis Report Description Acceptance Criteria YMRP Criteria 
The Safety Analysis Report contains a complete list of features, 
events, and processes, related to the geologic setting or the 
degradation, deterioration, or alteration of engineered barriers 
(including those processes that would affect the performance of 
natural barriers) that have the potential to influence repository 
performance. The list is consistent with the site characterization 
data. Moreover, the comprehensive features, events, and 
processes list includes, but is not limited to, potentially disruptive 
events related to igneous activity (extrusive and intrusive); 
seismic shaking (high-frequency-low magnitude, and rare largemagnitude 
events); tectonic evolution (slip on existing faults and 
formation of new faults); climatic change (change to pluvial 
The list of DE FEPs is provided in Section 1.2, 
and FEP Descriptions are provided in Section 
6.2. See Section 6.1.1 for a description and 
origin of the DE FEP list and descriptions. 
This report does not address climatic change 
or criticality. 
1. The Identification 
of a List of 
Features, Events, 
and Processes Is 
Adequate 
conditions); and criticality. 
The DOE has identified all features, events, and processes 
related to either the geologic setting or to the degradation, 
deterioration, or alteration of engineered barriers (including those 
processes that would affect the performance of natural barriers) 
that have been excluded. 
See Table 7-1 for a list of excluded DE FEPs. 
Scenario Analysis 
and Event 
Probability: 
Scenario Analysis The DOE has provided justification for those features, events, 
and processes that have been excluded. An acceptable 
justification for excluding features, events, and processes is that 
either the feature, event, and process is specifically excluded by 
regulation; probability of the feature, event, and process 
(generally an event) falls below the regulatory criterion; or 
omission of the feature, 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. 
See the method and approach discussion 
provided in Section 6.1.2, and the individual 
justifications (by regulation, low probability, low 
(from 
Section 2.2.1.2.1.3 
[DIRS 163274]) 
consequence) for excluding FEPs provided in 
Section 6.2. The justification is also included 
2. Screening of the 
Initial List of 
Features, Events, 
in Table 7-1. 
and Processes Is 
Appropriate 
The DOE has provided an adequate technical basis for each 
feature, event, and process, excluded from the performance 
assessment, to support the conclusion that either the feature, 
event, or process is specifically excluded by regulation; the 
probability of the feature, event, and process falls below the 
regulatory criterion; or omission of the feature, event, and 
process does not significantly change the magnitude and time of 
the resulting radiological exposures to the reasonably maximally 
exposed individual, or radionuclide releases to the accessible 
environment. 
See Section 6.2 for discussion of the individual 
FEP depositions and supporting technical 
bases. 
Decemberr 2003 
Table 4-7. YMRP Criteria and the DE FEPs AMR (Continued) 
Features, Events and Processes: Disruptive Events 
ANL-WIS-MD-000005 REV 01 32 
How Addressed in this Analysis Report Description Acceptance Criteria YMRP Criteria 
Events or event classes are defined without ambiguity and used See the FEP Description provided for each 
consistently in probability models, such that probabilities for each FEP in Section 6.2 and the cited supporting 
AMRs. event or event class are estimated separately; 
Probabilities of intrusive and extrusive igneous events are 
calculated separately. Definitions of faulting and earthquakes 
are derived from the historical record, paleoseismic studies, or 
Probabilities related to igneous processes 
were developed based on the results of the 
expert elicitation documented in the PVHA 
(CRWMS M&O 1996 [DIRS 100116]), and 
further developed in Characterize Framework 
for Igneous Activity at Yucca Mountain Nevada 
ANL-MGR-GS-000001 REV 01 (BSC 2003 
[DIRS 163769]). Separate probabilities are 
determined for an intrusive and an eruptive 
event. This report does not address criticality 
FEPs. 
Scenario Analysis 
and Event 
Probability: 1. Events are 
Adequately 
Defined 
geological analyses. Criticality events are calculated separately 
by location. 
Identification of 
Events with 
Probability Greater 
than 10-8 Per Year 
(from 
Section 2.2.1.2.2.3 
[DIRS 163274]) 
2. Probability 
Estimates for 
Future Events Are 
Probabilities for future natural events are based on past patterns 
of the natural events in the Yucca Mountain region, considering 
the likely future conditions and interactions of the natural and 
See FEP discussions in Section 6.2 for a list of 
naturally occuring seismic and igneous FEPs 
that are addressed. Probability discussions 
are provided for each FEP as needed. This 
analysis report does not address criticality 
FEPs. 
Supported by 
Appropriate 
Technical Bases 
engineered repository system. These probability estimates have 
specifically included igneous events, faulting and seismic events, 
and criticality events. 
Decemberr 2003 
Table 4-7. YMRP Criteria and the DE FEPs AMR (Continued) 
Features, Events and Processes: Disruptive Events 
Description Acceptance Criteria YMRP Criteria 
1. Probability models are justified through comparison with 
output from detailed process-level models and/or empirical 
observations (e.g., laboratory testing, field measurements, 
3. Probability Model Although the DE FEPs do not develop any 
probability estimates (aside from that for a 
hydrovolcanic event), the criterion is applicable 
to the probability estimates cited as a basis for 
inclusion. Annualized probabilities for various 
seismic events and fault displacements were 
determined using the expert elicitation process 
and are provided in the PSHA (CRWMS M&O 
1998 [DIRS 103731]). Probabilities related to 
igneous processes were developed based on 
the results of the expert elicitation documented 
in the PVHA (CRWMS M&O 1996 
[DIRS 100116]), and further developed in 
Scenario Analysis 
Support is 
Adequate 
and Event 
Probability: 
or natural analogs, including Yucca Mountain site data). 
Specifically: 
Decemberr 2003 ANL-WIS-MD-000005 REV 01 33 
How Addressed in this Analysis Report 
Identification of 
Events with 
Probability Greater 
a. For infrequent events, the DOE justifies, to the extent 
possible, proposed probability models with data from 
reasonably analogous systems. Analog systems 
than 10-8 Per Year 
should contain significantly more events that the Yucca 
Mountain system, to provide reasonable evaluations of from 
Section 2.2.1.2.2.3 
[DIRS 163274]) 
probability model performance. 
b. The DOE justifies, to the extent possible, the ability of 
probability models to reproduce the timing and 
characteristics (e.g., location and magnitude) of 
successive past events in the Yucca Mountain system; 
Characterize Framework for Igneous Activity at 
Yucca Mountain Nevada ANL-MGR-GS- 
000001 REV 01 (BSC 2003 [DIRS 163769]). 
The expert elicitations considered the issues of 
trying to determine probabilities from 
infrequent events and considered natural 
analogs, site data, and multiple alternative 
conceptual models including tectonic-based 
models. 
and 
c. The DOE probability models for natural events use 
underlying geologic basis (e.g., tectonic models) that 
are consistent with other relevant features, events, and 
processes evaluated, using Section 4.2.1.2.1. 
Table 4-7. YMRP Criteria and the DE FEPs AMR (Continued) 
Features, Events and Processes: Disruptive Events 
ANL-WIS-MD-000005 REV 01 34 
How Addressed in this Analysis Report Description Acceptance Criteria YMRP Criteria 
4. Probability Model 
Parameters Have 
Been Adequately 
1. Parameters used in probability models are technically justified Although the DE FEPs do not develop any 
and documented by the DOE. Specifically: 
Scenario Analysis 
probability estimates (aside from that for a 
hydrovolcanic event), the criterion is applicable 
to the probability estimates cited as a basis for 
inclusion. Annualized probabilities for various 
seismic events and fault displacements were 
determined using the expert elicitation process 
and are provided in the PSHA (CRWMS M&O 
1998 [DIRS 103731]). Probabilities related to 
igneous processes were developed based on 
the results of the expert elicitation documented 
in the PVHA (CRWMS M&O 1996 
[DIRS 100116]), and further developed in 
and Event 
Probability: 
Established a. Parameters for probability models are constrained by 
data from the Yucca Mountain region and engineered 
Identification of 
Events with 
Probability Greater 
repository system to the extent practical; 
b. The DOE appropriately establishes reasonable and 
consistent correlations between parameters: and 
than 10-8 Per Year 
c. Where sufficient data do not exist, the definition of 
parameter values and conceptual models is based on 
appropriate use of other sources, such as expert 
(From 
Section 2.2.1.2.2.3 
[DIRS 163274]) elicitation conducted in accordance with appropriate 
Characterize Framework for Igneous Activity at guidance. 
Yucca Mountain Nevada ANL-MGR-GS- 
000001 REV 01 (BSC 2003 [DIRS 163769]). 
The expert elicitations considered the issues of 
trying to determine probabilities from 
infrequent events and considered natural 
analogs, site data, and multiple alternative 
conceptual models including tectonic-based 
models. 
Annualized probabilities for various seismic 
events and fault displacements were 
determined using the expert elicitation process 
and are provided in the PSHA (CRWMS M&O 
1998 [DIRS 103731]). Probabilities related to 
igneous processes were developed based on 
the results of the expert elicitation documented 
in the PVHA (CRWMS M&O 1996 
[DIRS 100116]), and further developed in 
Scenario Analysis 5. Uncertainty in 
Event Probability 
is Adequately 
1. Probability values appropriately reflect uncertainties. 
and Event 
Probability: 
Specifically: 
Evaluated a. The DOE provides a technical basis for probability 
values used, and the values account for the uncertainty 
Identification of 
Events with 
Probability Greater 
in the probability estimates: and 
b. The uncertainty for reported probability values 
adequately reflects the influence of parameter 
uncertainty on the range of model results 
than 10-8 Per Year 
Characterize Framework for Igneous Activity at 
Decemberr 2003 
(From 
Section 2.2.1.2.2.3 
[DIRS 163274]) 
Yucca Mountain Nevada ANL-MGR-GS- 
000001 REV 01 (BSC 2003 [DIRS 163769]). 
The expert elicitations considered the issues of 
uncertainty and included the uncertainties in 
the estimation of the probability distributions 
and estimation of the mean value. 
(i.e., precision) and the model uncertainty, as it affects 
the timing and magnitude of past events 
(i.e., accuracy). 
Features, Events and Processes: Disruptive Events 
5. ASSUMPTIONS 
Only one generic assumption is used in screening the DE FEPs for the TSPA-LA. 
Assumption 5.1: For DE FEPs, it is assumed that regulations expressed as probability criterion 
can also be expressed as an annual exceedance probability, which is defined as the probability 
that a specified value will be exceeded during one year. More specifically, a stated probability 
screening criterion for very unlikely FEPs of one chance in 10,000 in 10,000 years (10-4/104 yr) 
criterion is assumed equivalent to a 10-8 annual-exceedance probability or annual-exceedance 
frequency. A stated definition of unlikely events as having one chance in 10 in 10,000 years 
(10-1/104 yr) of occurring is assumed equivalent to a 10-5 annual-exceedance probability or 
annual-exceedance frequency. 
Justification: The definition of annual-exceedance probability is taken from Characterize 
Framework for Seismicity and Structural Deformation at Yucca Mountain, Nevada 
(CRWMS M&O 2000, Glossary [DIRS 142321]). The use of this assumption is also justified in 
the same document, which indicates that the behavior of the earth is generally Poissonian or 
random, and is the underlying assumption in all probabilistic hazard analyses. 
The assumption of equivalence of annual-exceedance probability is appropriate if the 
possibility of an event is equal for any given year. This satisfies the definition of a 
Poisson distribution as  a mathematical model of the number of outcomes obtained in 
a suitable interval of time and space, that has its mean equal to its variance  (Merriam- 
Webster 1993, p. 899 [DIRS 100468]). This is inferred to mean that naturally occurring, 
infrequent, and independent events can be represented as stochastic processes in which 
distinct events occur in such a way that the number of events occurring in a given period 
depends only on the length of the time period. 
In terms of application to the DE FEPs, all earthquakes and igneous events 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 geologic processes 
that occur over long time spans, assuming annual equivalence over a 10,000-year period 
(a relatively short time span for geologic-related events) is reasonable and consistent with 
the basis of probabilistic hazard analyses. Therefore, no further confirmation is required. 
Use: This assumption is used throughout Section 6.2 of this report, either implicitly or explicitly, 
for each of the FEPs addressed in the analysis model report (AMR) that cite to an annualized 
probability or annual-exceedance frequency. 
35 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
INTENTIONALLY LEFT BLANK 
36 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
6.1 METHOD AND APPROACH 
The method and approach for FEP screening for TSPA-LA is provided in generic form in The 
Enhanced Plan for Features, Events, and Processes (FEPs) at Yucca Mountain (BSC 2002 
[DIRS 158966]) and the KTI Letter Report Response to Additional Information Needs on 
TSPAI 2.05 and TSPAI 2.06 (Freeze 2003 [DIRS 165394]). As described in the aforementioned 
documents, the YMP TSPA has chosen to satisfy the performance-assessment requirements by 
adopting a FEP analysis and scenario development approach. A review of FEP analysis and 
scenario development in other radioactive waste disposal programs is also provided in BSC 2002 
(Section 2 [DIRS 158966]) and includes a discussion of alternative FEP analysis methods and 
scenario development approaches. Regardless of the specific approach chosen to perform the 
screening, the screening process is, in essence, a comparison of the FEP against the criteria 
specified in Section 6.1.2 of this report. 
6. SCIENTIFIC ANALYSES 
The following subsections discuss the DE FEP analyses. Section 6.1 discusses the method and 
approach used for the DE FEP screening process, as well as changes in the DE FEP list from 
TSPA-SR to the TSPA-LA. Section 6.1 identifies the source of the DE FEPs, describes the FEP 
screening process, and provides documentation of generic issues related to uncertainty, 
alternative conceptual models, and model and software issues. Section 6.2 addresses the 
technical basis for the DE FEP screening. The FEP analyses presented in Section 6.2 are 
appropriate because, as described in Section 6.1, they are consistent with the TSPA approach to 
satisfy the performance-assessment requirements. Additionally, these analyses are also 
appropriate because they address NRCs Acceptance Criteria in the YMRP (NRC 2003, 
Section 2.2.1.2 [DIRS 163274] and are previously discussed in Section 4.2 of this analysis 
report). 
37 
6.1.1 DE FEPs Origin and Identification 
The first step of FEP analysis is the identification of FEPs potentially relevant to the 
performance of the Yucca Mountain repository. FEP analysis of the DE FEPs uses the following 
definitions, as taken from Freeze et al. (2001, Appendix A [DIRS 154365]): 
feature  an object, structure, or condition that has a potential to affect disposal 
system performance 
event  a natural or anthropogenic phenomenon that has a potential to affect 
disposal system performance and that occurs during an interval that is short 
compared to the period of performance 
process  a natural or anthropogenic phenomenon that has a potential to affect 
disposal system performance and that operates during all or a significant 
part of the period of performance. 
The development of a comprehensive list of FEPs that are potentially relevant to performance of 
the Yucca Mountain repository is an ongoing, iterative process based on site-specific 
information, design, and regulations. The approach for developing an initial list of FEPs in 
ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
support of TSPASR was documented in Freeze et al. (2001) [DIRS 154365]. The initial FEP 
list contained 328 FEPs, 176 of which were included in TSPA-SR models (CRWMS M&O 2000, 
Tables B-9 through B-17 [DIRS 153246]). Each FEP was assigned a unique YMP FEP database 
number, based on the Nuclear Energy Agency classification scheme (NEA 1992 
[DIRS 100479]). The database number is the primary method for identifying FEPs, and consists 
of an eight-digit number having a format of x.x.xx.xx.xx. A similar numbering system is used 
for the TSPA-LA FEP list to provide a unique identifier for each FEP. In general, TSPA-SR 
FEPs with numbers ending in .00 were converted to TSPA-LA FEPs with numbers ending in 
.0A. Where splitting existing TSPA-SR FEPs created new FEPs for TSPA-LA, the new FEPs 
end in .0B, .0C, etcetera, to ensure traceability to their origin in TSPA-SR FEP list. 
The results of the FEP activities planned in the TWP (BSC 2002 [DIRS 161737]) are 
documented in this analysis report as shown in Section 6.2. The revision of the FEPs 
organization and description was needed to implement The Enhanced Plan for Features Events 
and Processes (FEPs) at Yucca Mountain (BSC 2002 Section 3.2 [DIRS 158966]) and the KTI 
Letter Report Response to Additional Information Needs on TSPAI 2.05 and TSPAI 2.06 
(Freeze 2003 [DIRS 165394]). The particular revision efforts included: 
 Review of the FEPs hierarchical system 
 Re-categorization and redefinition of the DE FEPs as needed to provide a consistent and 
appropriate level of detail 
 Review of updated analysis reports and model reports as needed, and integration with 
SMEs. 
The reorganization and reevaluation of the TSPA-SR DE FEPs resulted in a revised list of 20 DE 
FEPs as extracted from the TSPA-LA FEP list (DTN: MO0307SEPFEPS4.000 [DIRS 164527]. 
Changes to the list, including additions and deletions during the review process, are given in 
Table 6-1. Table 6-1 summarizes the changes from TSPASR to the FEP organization and 
descriptions being used for TSPA-LA that appear in this report, and provides a comparison of the 
resulting screening decisions and report basis as provided in Section 6.2. Additional changes 
made in the descriptions from the cited DTN also are presented in Table 6-1 under the TSPA-LA 
description heading. The changes are shown italicized in Table 6-1. 
38 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
ANL-WIS-MD-000005 REV 01 
Table 6-1. Changes to the DE FEPs from TSPA-SR to TSPA-LA 
TSPA-LA FEP and Description Analysis 
Report 
Section 
Basis for Change 
from TSPA-SR to 
TSPA-LA FEP list 
TSPA-SR 
SCREENING 
DECISION 
(italics denote changes from 
TSPASR FEP and Description DTN: MO0307SEPFEPS4.000 [DIRS 164527]) 
1.2.01.01.0A Tectonic activitylarge scale 1.2.01.01.00 Tectonic activitylarge scale 
Large-scale tectonic activity includes regional 
uplift, subsidence, folding, mountain building, 
and other processes related to plate 
movements. These tectonic events and 
processes could affect repository performance 
by altering the physical and thermo-hydrologic 
properties of the geosphere. 
Large-scale tectonic activity includes regional uplift, 
subsidence, folding, mountain building, and other 
processes related to plate movements. These 
No changes in FEP 
Description between 
TSPA-SR and TSPALA 
FEP Lists. 
Excluded 
Low 
Consequence 
6.2.1.1 tectonic events and processes could affect 
repository performance by altering the physical and 
thermohydrologic properties of the geosphere. 
1.2.02.01.00 Fractures FEP Description 
redefined to address 
existing 
characteristics only. 
Changes, 
reactivation, new 
fracture development 
due to disruptive 
events now 
addressed in a new 
FEP 2.2.06.02.0B 
Seismic activity 
changes porosity and 
permeability of 
fractures. 
Groundwater flow in the Yucca Mountain region 
and transport of any released radionuclides 
may take place along fractures. Transmissive 
fractures may be existing, reactivated, or newly 
formed fractures. The rate of flow and the 
extent of transport in fractures is influenced by 
characteristics such as orientation, aperture, 
asperity, fracture length, connectivity, and the 
nature of any linings or infills. Generation of 
new fractures and reactivation of preexisting 
fractures may significantly change the flow and 
transport paths. Newly formed and reactivated 
fractures typically result from thermal, seismic, 
or tectonic events. 
Included for 
existing 
characteristics: 
December 2003 39
Not ApplicableNot Assigned to DE FEPs for Not 
Applicable Excluded for TSPA-LA. changes to 
characteristics 
Low 
Consequence 
Table 6-1. Changes to the DE FEPs from TSPA-SR to TSPA-LA (Continued) 
TSPA-SR 
SCREENING 
DECISION 
Included for 
existing Faulting may occur due to sudden major 
changes in the stress situation (e.g., seismic 
activity) or due to slow motions in the rock mass Excluded for 
(e.g., tectonic activity). Movement along changes in 
existing fractures and faults is more likely than fault properties 
the formation of new faults. Faulting may alter and new 
the rock permeability in the rock mass and alter 
or short-circuit the flow paths and flow 
distributions close to the repository and create 
new pathways through the repository. New 
faults or the reactivation of existing faults may 
enhance the groundwater flow, thus decreasing 
the transport times for potentially released 
radionuclides. 
characteristics: 
faultsLow 
Consequence 
for changes to 
existing 
characteristics 
and low 
probability for 
new faults. 
Excluded 
Features, Events and Processes: Disruptive Events 
ANL-WIS-MD-000005 REV 01 
TSPA-LA FEP and Description Analysis 
Report 
Section 
Basis for Change 
from TSPA-SR to 
TSPA-LA FEP list 
(italics denote changes from 
TSPASR FEP and Description DTN: MO0307SEPFEPS4.000 [DIRS 164527]) 
1.2.02.02.00 Faulting 
FEP redefined to 
address existing 
characteristics only. 
Changes, 
reactivation, new 
fracture development 
due to disruptive 
events now 
addressed in a new 
FEP 2.2.06.02.0A 
Seismic activity 
changes porosity and 
permeability of faults. 
Not 
Applicable TSPA-LA 
Not ApplicableNot Assigned to DE FEPs for 
1.2.02.03.0A Fault displacement damages EBS 1.2.02.03.00 Fault movement shears waste 
container 
December 2003 40 
FEP redefined to 
address the potential 
for a variety of 
damage types to 
EBS components 
stemming from fault 
movement, rather 
than limiting 
discussion to only 
shearing and waste 
containers only. 
components 
A fault intersects drifts within the repository. The 
fault undergoes movement. The EBS components 
experience related movement or displacement 
A fault intersects the repository and a line of 
waste containers. That intersection shears 
containers by virtue of the relative offset across 
the containers. such that performance is degraded by such things 
as tilting of components, component-to-component 
contact, or drip shield separation. Or, it could be 
6.2.1.2 Low Probability 
as significant as failure due to the shearing of drip 
shields and waste packages by virtue of the 
relative offset across the fault, or as extreme as 
exhumation to the surface. 
Features, Events and Processes: Disruptive Events 
ANL-WIS-MD-000005 REV 01 
Table 6-1. Changes to the DE FEPs from TSPA-SR to TSPA-LA (Continued). 
Analysis 
Report 
Section 
Basis for Change 
from TSPA-SR to 
TSPA-LA FEP list 
TSPA-LA FEP and Description 
TSPA-SR SCREENING (italics denote changes from 
DTN: MO0307SEPFEPS4.000 [DIRS 164527]) DECISION 
Excluded for indirect 
TSPASR FEP and Description 
1.2.03.01.00 Seismic activity 
effectsLow 
Consequence Seismic activity (i.e., earthquakes) 
could produce jointed-rock motion, 
rapid fault growth, slow fault growth or 
This FEP description 
was reevaluated and 
found to be too 
broad and redundant 
with other seismicrelated 
FEPs and 
was deleted. 
Excluded for breaching 
of drip shield, and of the 
emplacement pallet and 
Not 
Applicable 
Not ApplicableNot Assigned to DE FEPs for new fault formation, resulting in 
changes in hydraulic heads, changes 
in groundwater recharge or discharge 
TSPA-LA. 
waste packageLow 
Consequence zones, changes in rock stresses, and 
severe disruption of the integrity of the 
drifts (e.g., vibration damage, rockfall). 
Includedfor fuel-rodcladding 
damage. 
1.2.03.02.00 Seismic vibration causes 1.2.03.02.0A Seismic ground motion damages EBS FEP Description was 
split to better 
address effects due 
to ground motion 
and rockfall effects 
as related to events, 
and each description 
was expanded to 
address EBS 
components in 
addition to waste 
containers. See 
also FEP 
1.2.03.02.0B 
Seismic-induced 
rockfall damages 
EBS component. 
Excluded for breaching 
of drip shield, and of the 
emplacement pallet and 
container failure components 
Seismic activity causes repeated 
vibration of container and/or container- 
Seismic activity causes repeated vibration of the 
EBS components (drip shield, waste package, 
pallet, and invert). This could result in severe 
waste packageLow 
Consequence rock wall contact, damaging the 
container and its contents. 
December 2003 41 
Included for fuel-rod 
cladding damage. 
disruption of the drip shields and waste packages 
through vibration damage or contact between EBS 
components. Such damage mechanisms could lead 6.2.1.3 
to degraded performance. 
Table 6-1. Changes to the DE FEPs from TSPA-SR to TSPA-LA (Continued) 
TSPA-LA FEP and Description 
(italics denote changes from 
DTN: MO0307SEPFEPS4.000 [DIRS 164527]) 
1.2.03.02.0B Seismic-induced rockfall damages 
EBS components 
Seismic activity could produce jointed-rock 
motion and/or changes in rock stress leading to 
enhanced rockfall that could impact drip shields, 
waste packages, or other EBS components. 
1.2.03.02.0C Seismic-induced drift collapse 
damages EBS components 
Features, Events and Processes: Disruptive Events 
TSPA-SR 
SCREENING 
DECISION 
Not Applicable 
Not Applicable 
Not Applicable 
Excluded for indirect 
ANL-WIS-MD-000005 REV 01 
Analysis 
Report 
Section 
TSPASR FEP and 
Description 
Basis for Change from TSPASR 
to TSPA-LA FEP list 
NEW FEP. Previous FEP 
Description was split to better 
address effects due to ground 
motion and rockfall effects as 
related to events, and each 
description expanded to 
address EBS components in 
addition to waste packages. 
See also FEP 1.2.03.02.0A 
Seismic ground motion 
damages EBS components. 
Not Applicable (NEW FEP) 6.2.1.4 
NEW FEP. Previous TSPA-LA 
FEP Description for drift 
collapse was split to better 
address effects on EBS 
components and waste 
packages and better parallel the 
discussion of seismic-induced 
rockfall effects. 
Seismic activity could produce jointed-rock 
motion and/or changes in rock stress leading to 
enhanced drift collapse that could impact drip 
shields, waste packages, or other EBS 
components. Possible effects include both 
dynamic and static loading. 
6.2.1.5 Not Applicable (NEW FEP) 
42 
1.2.03.02.0D Seismic-induced drift collapse 
alters in-drift thermohydrology 
NEW FEP. Previous TSPA-LA 
FEP Description for drift 
collapse was split to better 
address effects in the in-drift 
environment following drift 
collapse. 
Seismic activity could produce jointed-rock 
motion and/or changes in rock stress leading to 
enhanced drift collapse and/or rubble infill 
throughout part or all of the drifts. Drift collapse 
could impact flow pathways within the EBS, 
mechanisms for water contact with EBS 
components, and thermal properties within the 
6.2.1.6 Not Applicable (NEW FEP) 
December 2003 
EBS. 
1.2.03.03.00 Seismicity 
associated with igneous activity 
1.2.03.03.0A Seismicity associated with igneous 
activity effectsLow 
Consequence 
No changes in FEP Description 
between TSPA-SR and TSPA- Seismicity associated with 
future igneous activity in the 
Yucca Mountain region may 
affect repository performance. 
6.2.1.7 Seismicity associated with future igneous activity 
in the Yucca Mountain region may affect 
repository performance. 
LA FEP Lists. Included for fuel-rod 
cladding damage. 
Features, Events and Processes: Disruptive Events 
ANL-WIS-MD-000005 REV 01 
Table 6-1. Changes to the DE FEPs from TSPA-SR to TSPA-LA (Continued). 
Analysis 
Report 
Section 
TSPA-SR 
SCREENING 
DECISION 
TSPA-LA FEP and Description 
Basis for Change from TSPASR 
to TSPA-LA FEP list 
TSPASR FEP and 
Description 
(italics denote changes from 
DTN: MO0307SEPFEPS4.000 [DIRS 164527]) 
1.2.10.01.00 Hydrological 
response to seismic activity 
1.2.10.01.0A Hydrologic response to seismic 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. 
activity 
Seismic activity, associated with fault movement, 
may create new or enhanced flow pathways 
and/or connections between stratigraphic units, 
No changes in FEP Description 
between TSPA-SR and TSPA- ExcludedLow 
Consequence 6.2.1.8 
or it may change the stress (and therefore fluid 
pressure) within the rock. These responses 
have the potential to significantly change the 
LA FEP Lists. 
surface and groundwater-flow directions, water 
level, water chemistry, and temperature. 
Seismic-related rockfall is 
addressed now by a separate 
FEP 1.2.03.02.0B Seismic- 
2.1.07.01.00 Rockfall (large 
block) 
December 2003 43 
ExcludedLow 
Consequence 
Not ApplicableNot Assigned to DE FEPs for Not 
Applicable Rockfalls occur large enough to 
mechanically tear or rupture 
waste packages. 
TSPA-LA. induced rockfall damages EBS 
components, to better address 
the level of detail. 
Features, Events and Processes: Disruptive Events 
ANL-WIS-MD-000005 REV 01 
Table 6-1. Changes to the DE FEPs from TSPA-SR to TSPA-LA (Continued). 
Analysis 
Report 
Section 
TSPA-SR 
SCREENING 
DECISION 
TSPA-LA FEP and Description Basis for Change from TSPASR 
to TSPA-LA FEP list 
TSPASR FEP and 
Description (italics denote changes from 
DTN: MO0307SEPFEPS4.000 [DIRS 164527]) 
2.1.07.02.00 Mechanical 
degradation or collapse of drift 
Partial or complete collapse of 
the drifts, as opposed to 
discrete rockfall, could occur as 
a result of seismic activity, 
thermal effects, stresses related 
to excavation, or possibly other 
mechanisms. Drift collapse 
could affect stability of the 
engineered barriers and waste 
packages. Drift collapse may 
be localized as stoping at faults 
or other geologic features. 
Rockfall of small blocks may 
produce rubble throughout part 
or all of the drifts. 
Seismic induced drift collapse 
effects now addressed by two 
new FEPs 1.2.03.02.0C 
Seismic-induced drift collapse 
damages EBS components, 
Not ApplicableNot Assigned to DE FEPs for Excluded Low 
Consequence Not Applicable TSPA-LA. 
and FEP 1.2.03.02.0D Seismicinduced 
drift collapse alters indrift 
thermohydrology. 
44 
2.2.06.01.00 Changes in stress 
(due to thermal seismic or 
tectonic effects) change 
porosity and permeability of 
rock. 
Changes in stress due to all 
causes, including heating, 
seismic activity, and regional 
tectonic activity, have a 
potential [to] result in strains 
that affect flow properties in 
rock outside the excavationdisturbed 
zone. 
2.2.06.01.0A Seismic activity changes porosity 
and permeability of rock. 
Seismic activity (fault displacement or vibratory limit discussion in this FEP to 
ground motion) has a potential to change rock seismic-related events. 
stresses and result in strains that affect flow 
properties in rock outside the excavationdisturbed 
zone. It could result in strains that alter part of the nominal case 
the permeability in the rock matrix. These effects analysis. 
may decrease the transport times for potentially 
released radionuclides. 
FEP Description modified to 
ExcludedLow 
Consequence 6.2.1.9 Thermal effects of the 
repository are addressed as 
December 2003 
Features, Events and Processes: Disruptive Events 
ANL-WIS-MD-000005 REV 01 
Table 6-1. Changes to the DE FEPs from TSPA-SR to TSPA-LA (Continued). 
Analysis 
Report 
Section 
TSPA-SR 
SCREENING 
DECISION 
TSPA-LA FEP and Description 
Basis for Change from TSPASR 
to TSPA-LA FEP list 
TSPASR FEP and 
Description 
(italics denote changes from DTN: 
MO0307SEPFEPS4.000 [DIRS 164527]) 
NEW FEP created for 
consistent level of detail to 
address changes in fractures, 
similar to that for rocks and 
faults. This FEP Description 
limits discussion in this FEP to 
seismic-related events. Due to 
the linkage between changes in 
stress, fracturing, and changes 
in fractures characteristics, 
these aspects of fracturing have 
been incorporated from the 
TSPA-SR FEP 1.2.02.01.00 
Fractures. Thermal effects of 
the repository are addressed as 
part of the nominal case 
analysis. 
2.2.06.02.0B Seismic activity changes porosity 
and permeability of fractures 
Seismic activity (fault displacement or vibratory 
ground motion) has a potential to change stress 
and strains that alter the permeability along 
fractures. This could result in reactivation of 
preexisting fractures or generation of new 
fractures. Generation of new fractures and 
reactivation of preexisting fractures may 
significantly change the flow and transport paths, 
alter or short-circuit the flow paths and flow 
distributions close to the repository and create 
new pathways through the repository. These 
effects may decrease the transport times for 
potentially released radionuclides. 
6.2.1.11 Not Applicable Not Applicable (NEW FEP) 
45 
2.2.06.03.00 Changes in stress 
(due to seismic or tectonic 
effects) alters perched-water 2.2.06.03.0A Seismic activity alters perched 
water zones 
Strain caused by stress changes from tectonic or 
seismic events alters the rock permeabilities that 
allow formation and persistence of perched water 
zones. 
zones. 
No changes in FEP Description 
between TSPA-SR and TSPALA 
FEP Lists. 
Strain caused by stress 
changes from tectonic or 
ExcludedLow 
Consequence 6.2.1.12 
seismic events alters the rock 
permeabilities that allow 
formation and persistence of 
perched-water zones. 
December 2003 
Features, Events and Processes: Disruptive Events 
ANL-WIS-MD-000005 REV 01 
Table 6-1. Changes to the DE FEPs from TSPA-SR to TSPA-LA (Continued). 
Analysis 
Report 
Section 
TSPA-SR 
SCREENING 
DECISION 
Basis for Change from 
TSPA-SR to TSPA-LA 
TSPA-LA FEP and Description 
(italics denote changes from 
DTN: MO0307SEPFEPS4.000 [DIRS 164527]) TSPASR FEP and Description FEP list 
1.2.04.01.00 Igneous activity 
Volcanism and magmatic activity 
could cause activation, creation and 
sealing of faults, changes in 
topography, changes in rock stress, 
deformation of rock, changes in 
groundwater temperatures, and 
severe perturbation to the integrity of Consequence 
the drifts. 
Included for This FEP Description was 
reevaluated and found to direct effects 
Excluded for 
indirect effects 
Not ApplicableNot Assigned to DE FEPs for 
TSPA-LA 
be too broad and 
redundant with other 
igneous-related FEPs and 
Not 
Applicable 
Low was deleted. 
1.2.04.02.0A Igneous activity changes rock 
properties 
Igneous activity near the underground facility causes 
extreme changes in rock stress and the thermal 
regime, and may lead to rock deformation including 
activation, creation, and sealing of faults and 
fractures. This may cause changes in the rock 
hydrologic and mineralogic properties. 
Permeabilities of dikes and sills and the heated 
regions immediately around them can differ from 
those of country rock. Mineral alterations can also 
change the chemical response of the host rock to 
contaminants. 
1.2.04.02.00 Igneous activity 
causes changes to rock properties. 
Igneous activity near the 
underground facility causes extreme 
changes to rock hydrologic and 
mineralogic properties. 
Permeabilities of dikes and sills and 
the heated regions immediately 
around them can differ from those of 
country rock. Mineral alterations 
can also change the chemical 
response to contaminants. 
FEP Description modified 
to address concerns with 
thermal changes due to ExcludedLow 
Consequence 6.2.2.1 intrusion and to clarify that 
chemical response of host 
46
rock is at issue. 
1.2.04.03.00 Igneous intrusion into 
repository 
Magma from an igneous intrusion 
flows into the drifts and extends over 
a portion of the repository site, 
forming a sill. The sill could be 
limited to the drifts or a continuous 
sill could form along the plane of the 
repository, bridging between 
adjacent drifts. 
1.2.04.03.0A Igneous intrusion into repository 
Magma from an igneous intrusion flows into the 
drifts and extends over a large portion of the 
repository site, forming a sill, dike, or dike swarm 
depending on the stress conditions. This could 
involve multiple drifts. The sill could be limited to the 
drifts or a continuous sill could form along the plane 
of the repository, bridging between adjacent drifts. 
FEP Description modified 
to address concerns with 
dike/repository interaction 6.2.2.2 Included 
December 2003 
associated with intrusion. 
Features, Events and Processes: Disruptive Events 
Table 6-1. Changes to the DE FEPs from TSPA-SR to TSPA-LA (Continued). 
TSPA-LA FEP and Description Analysis 
Report 
Section 
TSPA-SR 
SCREENING 
DECISION 
Basis for Change from 
TSPA-SR to TSPA-LA TSPASR FEP and Description (italics denote changes from 
DTN: MO0307SEPFEPS4.000 [DIRS 164527]) 
1.2.04.04.0A Igneous intrusion interacts with EBS 
components 
An igneous intrusion in the form of a dike occurs 
through the repository, intersecting the repository 
drifts. Magma, pyroclastics, and volcanic gases 
enter the drift and interact with the EBS components 
including the drip shields, the waste packages, 
pallet, and invert. This leads to accelerated drip 
shield and waste package failure (e.g., attack by 
magmatic volatiles, damage by flowing or 
fragmented magma, thermal effects) and dissolution 
or volatilization of waste. 
1.2.04.05.0A Magma or pyroclastic base surge 
transports waste. 
As a result of the igneous intrusion, extrusive 
processes result in a pyroclastic density flow, base 
surge, dike apron, effusive lava flows and/or 
development of a volcanic vent at land surface. 
Some of the waste (entrained, dissolved, or 
volatized) is then transported away from the 
repository. Of most concern is transport directly 
ANL-WIS-MD-000005 REV 01 
FEP list 
1.2.04.04.00 Magma interacts with 
waste 
An igneous intrusion in the form [of a 
dike] occurs through the repository, 
intersecting waste. This leads to 
accelerated waste container failure 
(e.g., attack by magmatic volatiles, 
damage by fragmented magma, 
thermal effects) and dissolution of 
waste (CSNF, DSNF, DHLW). 
FEP Description modified 
to address concerns with 
dike/repository interaction 
associated with intrusion 6.2.2.3 Included and to clarify that 
interaction is with EBS 
components, not just 
waste. 
Excluded for 1.2.04.05.00 Magmatic transport of 
waste 
An igneous intrusion occurs through 
the repository, intersecting waste. 
Some of the waste (entrained, 
dissolved, or volatilized) is then 
transported away from the 
repository. Of most concern is 
transport directly to the surface. 
FEP Description and Name 
modified to better address 
surface effects associated 
transport in liquid 
magma and 
other types of with effusive flow, 
interaction associated with 
intrusion, and to clarify that 
47 
transportLow 
Consequence 6.2.2.4 
interaction is with EBS 
components, not just Included for 
transport through 
eruptive events. waste. 
along the land surface to the RMEI. 
1.2.04.06.00 Basaltic cinder cone 
erupts through the repository 
As a result of an igneous intrusion, a 
cinder cone forms on the surface. 
The conduit(s) supplying the vent(s) 
of the cone pass(es) through the 
repository, interacting with and 
entraining waste. 
1.2.04.06.0A Eruptive conduit to surface intersects 
repository 
As a result of an igneous intrusion, one or more 
volcanic vents forms at land surface. The conduit(s) 
supplying the vent(s) pass(es) through the 
repository, interacting with and entraining waste. 
FEP Description and Name 
modified to be more 
technically correct 
regarding development of 
surface and subsurface 
features and related 
concerns. 
6.2.2.5 Included 
December 2003 
Table 6-1. Changes to the DE FEPs from TSPA-SR to TSPA-LA (Continued). 
Features, Events and Processes: Disruptive Events 
ANL-WIS-MD-000005 REV 01 
Basis for Change from 
TSPA-SR to TSPA-LA 
TSPA-LA FEP and Description TSPA-SR 
SCREENING 
DECISION 
Included 
Analysis Report 
Section 
(italics denote changes from 
DTN: MO0307SEPFEPS4.000 [DIRS 164527]) TSPASR FEP and Description FEP list. 
1.2.04.07.0A Ashfall 
Finely-divided waste particles are 
carried up a volcanic vent and 
deposited [at land] surface from an 
ash cloud or pyroclastic flow. 
1.2.04.07.0A Ashfall 
Finely-divided waste particles are carried up a 
volcanic vent and deposited at land surface from an 
ash cloud. 
No changes in FEP 
Description between 
TSPA-SR and TSPA-LA 
Excluded for 6.2.2.6 pyroclastic base 
surge flowLow 
Consequence. 
FEP Lists. 
1.2.04.07.0C Ash redistribution via soil and sediment 
transport 
Following deposition of contaminated ash on the 
surface, ash deposits may be redistributed on the 
surface via aeolian and fluvial processes. 
New FEP created to 
address post-eruptive 
effects of ashfall with Not Applicable Not Applicable (NEW FEP) 6.2.2.7 regard to mechanisms 
for contaminant 
transport. 
1.2.10.02.00 Hydrologic response 
to igneous activity 
Igneous activity may change the 
groundwater flow directions, water 
level, water chemistry and 
temperature. Igneous activity 
includes magmatic intrusions, which 
may change rock properties and 
flow pathways, and thermal effects 
which may heat up groundwater and 
rock. 
1.2.10.02.0A Hydrologic response to igneous activity 
Igneous activity includes magmatic intrusions, which 
may alter groundwater flow pathways, and thermal 
effects, which may heat up groundwater and rock. 
Igneous activity may change the groundwater flow 
directions, water level, water chemistry, and 
temperature. Eruptive and extrusive phases may 
change the topography, surface drainage patterns, 
and surface soil conditions. This may affect 
infiltration rates and locations. 
FEP Description modified 
to more clearly identify 
potential for hydrologic 
December 2003 48 
ExcludedLow 
Consequence 6.2.2.8 response due to surface 
effects of igneous 
activity. 
Features, Events and Processes: Disruptive Events 
6.1.2 FEP Screening Process 
As described in Section 6.1.1, the first step in the FEP analysis was the identification of the 
FEPs. The second step includes the screening of each FEP against the FEP screening criteria. 
Each FEP is screened against regulations, guidance, or specific criteria that are summarized in 
the form of three FEP screening statements: 
(1) The event has at least one chance in 10,000 of occurring over 10,000 years (see 
10 CFR 63.114(d) (66 FR 55732 [DIRS 156671])) 
(2) The magnitude and time of the resulting radiological exposure to the RMEI, or 
radionuclide release to the accessible environment, would be significantly changed by 
its omission (see 10 CFR 63.114 (e and f) (66 FR 55732 [DIRS 156671])). 
Additionally, the Acceptance Criteria in the YMRP (NRC 2003, Section 2.2.1.2.1.3 
[DIRS 163274]) calls for evaluating the FEPs based on the regulations. This criterion can be 
summarized in the form of a third FEP screening statement: 
(3) The FEP is not excluded by regulation. 
If there are affirmative conditions for all three screening criteria, the FEP is Included in the 
TSPA-LA model. By default, FEPs are included in the TSPA, unless they are shown to be of 
low probability, of low consequence, or excluded by regulation. Any negating condition in the 
three screening criteria Excludes the FEP from the TSPA-LA model. 
For postclosure evaluation of fault-displacement and ground-motion related DE FEPs for 
TSPA-LA FEPs, the FEP screening statements are applied based on the mean value of the event 
at an annual-exceedance probability of 10-8 (see Assumption 5.1). For the TSPA-SR, the DOE 
elected to use median hazard curves to screen seismic FEPs, considering the median curve 
representative of the hazards central tendency at an annual-exceedance frequencies lower than 
approximately 10-6. However, NRC reviewers suggested that using the median hazard for FEP 
screening is inconsistent with established NRC practice for use of PSHA in risk assessment. 
Consequently, the DOE has implemented an alternative approach for TSPA-LA that uses the 
mean values. This alternative approach is documented in Williams 2001 [DIRS 161728]. 
The use of the mean value is consistent with the requirements of 10 CFR 63.305(c) 
(66 FR 55732 [DIRS 156671]), which requires that DOE vary factors related to geology, 
hydrology and climate, based upon cautious, but reasonable assumptions, consistent with present 
knowledge of factors that could affect the Yucca Mountain disposal system in the next 10,000 
years. The justification and reasoning for using the mean value is fully explained in Williams 
(2001 [DIRS 161728]). The use of the mean value is cautious in that it incorporates large 
uncertainties and significantly exceeds any single-event displacements observed along existing 
structures at Yucca Mountain. The use of the mean values is also consistent with established 
NRC practice and guidance procedures that use the mean value as the appropriate representation 
of hazard uncertainty. Moreover, the use of the mean value is consistent with present 
knowledge of factors in that ground-motion and fault-displacement hazard evaluations, 
following standard practice, have been modeled assuming an unbounded lognormal distribution 
for the ground motion uncertainty. 
ANL-WIS-MD-000005 REV 01 49 Features, Events and Processes: Disruptive Events 
The use of the mean value from the hazard curve is particularly pertinent to the following FEPs: 
1.2.02.03.0A Fault displacement damages EBS components (Section 6.2.1.2) 
1.2.03.02.0A Seismic ground motion damages EBS components (Section 6.2.1.3) 
1.2.03.02.0B Seismic-induced rockfall damages EBS components (Section 6.2.1.4) 
1.2.03.02.0C Seismic-induced drift collapse damages EBS components (Section 6.2.1.5) 
1.2.03.02.0D Seismic-induced drift collapse alters in-drift thermohydrology 
(Section 6.2.1.6). 
The postclosure FEP screening considers the three screening criteria, two of which are: (1) the 
probability of the phenomenon occurring (Section 6.1.2.1), and (2) the consequence of omitting 
the FEP (the potential to affect disposal system performance; i.e., the associated combinations of 
repository system component failures in response to the phenomenon) (Section 6.1.2.2). The 
third criterion (By Regulation) is discussed in Section 6.1.2.3. 
6.1.2.1 Exclusion by Low Probability 
For the TSPA postclosure consideration, an event is defined as a natural or anthropogenic 
phenomenon that has a potential to affect disposal system performance and that occurs during an 
interval that is short compared to the period of performance (Freeze et al. 2001, Appendix A 
[DIRS 154365]). For postclosure, the event probability criterion is set at one chance in 10,000 of 
the event occurring in 10,000 years (10 CFR 63.114(d) 66 FR 55732 [DIRS 156671]). 
Event probability screening is the consideration of the probability of a phenomenon occurring, 
independent of its effect on the repository. This is particularly germane to processes where the 
phenomena are well defined. If it can be demonstrated that a phenomenon, independent of its 
effect on the repository, is of sufficiently low probability, then the phenomenon is Excluded from 
the TSPA based on low probability. This report does not use this screening criterion as the sole 
basis for FEP exclusion, as the evaluated events (volcanism and seismic events) occur at annual 
frequencies greater than 10-8. 
6.1.2.2 Exclusion by Low Consequence 
This screening criterion allows FEPs to be excluded from further consideration if the magnitude 
and time of the resulting radiological exposures to the RMEI, or radionuclide releases to the 
accessible environment would not be significantly changed by the omission of the FEP from 
the TSPA-LA model. The terms significantly changed and changed significantly are 
undefined terms in the NRC and EPA regulations. The absence of significant change (i.e., an 
insignificant change if the FEP is omitted) is inferred for FEP-screening purposes to be 
equivalent to having no effect or negligible effect. 
The low-consequence argument can be made for FEP screening by demonstrating that a 
particular FEP has negligible effect on the distribution of an intermediate-performance measure 
that can be linked to radiological exposure or radionuclide release, or it may be given directly in 
ANL-WIS-MD-000005 REV 01 50 Features, Events and Processes: Disruptive Events 
terms of the effect on radiological exposure or radionuclide release. If a FEP can be shown to 
have negligible impact on UZ or SZ flow and transport, waste-package integrity, and/or other 
components of the engineered barrier system (EBS) or natural barrier system (NBS) as modeled 
in the TSPA, then the FEP does not provide a mechanism that could result in a radiological 
exposure or radiological release increase. 
Various means to demonstrate negligible impact include site-specific data, sensitivity analyses, 
SMEs expertise (including, in some cases, the expert elicitation process), natural analogues, 
modeling studies outside the TSPA, and reasoned arguments based on literature research or 
corroborative data. Complicated processes, such as igneous- and seismic-related activity or 
waste corrosion FEPs, may require detailed analyses conducted specifically for the YMP. In 
some cases, the demonstration may be direct, using results of potential event or process computer 
simulations. For example, for FEP 2.2.06.01.0A (seismic activity changes porosity and 
permeability of rock), FEP 2.2.06.02.0A (seismic activity changes porosity and permeability of 
faults), and FEP 2.2.06.02.0B (seismic activity changes porosity and permeability of fractures), 
the FEP analysis considers the computer model results used to analyze the flow sensitivity to 
flow properties that would be affected by stress condition changes. The evaluation is based on 
intermediate properties (UZ flow) that are critical to radionuclide transport from the repository to 
the accessible environment. 
A low consequence argument, but based on probability, can be invoked if an event is defined in 
terms of its potential to affect the behavior (or response) of the disposal system (consequence), 
rather than solely in terms of the independent phenomenon probability. To evaluate this aspect 
one defines a threshold value at which an event has the potential to affect repository 
performance, and then defines the probability of that threshold being violated. Using the designbased 
FEP screening approach is justified because: 
(1) FEPs can be defined temporally, spatially, and in amplitude; 
(2) The phenomena and effect of the interaction can be quantified (or at least bounded) and, 
therefore, incorporated into the design in such a way that the potential effect of the FEP is 
eliminated or minimized; 
(3) The implementation of the design and changes to the design are subject to a performanceconfirmation 
process; and 
(4) The as-built design can be verified (see Section 6.1.7). 
This use of probability to support a low consequence argument is particularly germane to FEPs 
involving potential container breaching due to a geologic phenomenon. This report does not use 
the probability of exceeding a threshold tied to repository performance as the sole basis for FEP 
exclusion. 
Although a FEP is evaluated with regard to consequence, a low-consequence argument may also 
be supported by a low-probability argument for some portion of the FEP. In such cases, the 
basis for exclusion is shown as low consequence with the screening argument discussion 
mentioning the low probability of some portion of the FEP. An example of this is FEP 
2.2.06.02.0A (seismic activity changes porosity and permeability of faults) wherein the potential 
51 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
for new fault creation in intact rock is inferred to be of low probability based on the PSHA. 
However, the PSHA also indicates that significant movement along existing faults is likely to 
occur and, thus, the remainder of the FEP is further considered based solely on this consequence. 
In this particular case, the screening basis is listed as low consequence, as the phenomenon of 
fault displacement as a whole is not of low probability. 
Another method of supporting a low-consequence argument is to quantify the conditional 
exposure or conditional radionuclide release (i.e., that exposure or release which results 
presuming that the FEP occurs) and demonstrate that once weighted by the probability of the 
associated scenario class occurring, the exposure or release is of no significance. This particular 
method of supporting a low-consequence decision is not used to exclude any of the DE FEPs. 
6.1.2.3 Exclusion by Regulation 
The NRC Acceptance Criteria for FEP screening published in the YMRP (NRC 2003, 
Section 2.2.1.2.1.3 [DIRS 163274]) allows for exclusion of a FEP if the process is specifically 
excluded by the regulations as described in Acceptance Criterion 2, Screening of the Initial List 
of Features, Events, and Processes Is Appropriate. FEPs that are contrary to specific 
regulations, regulatory assumptions, or regulatory intent as stated in the preamble sections of the 
regulations can be excluded from further consideration. Examples would include FEPs or 
assumptions that are contrary to the key concepts and definitions outlined in Section 4.1.3.1 of 
this report. Regulatory input for exclusion are used in the DE FEPs screening, particularly with 
regard to definition of the controlled area and its relationship to the location characteristics of the 
RMEI. 
6.1.3 Background, Supporting AMRs, Technical Information, and Literature Searches 
The data sources, product output, technical information, and references used for the FEP 
evaluations are cited within each of the individual FEPs discussions. The direct inputs for the 
excluded FEPs, and the list of included FEPs, are documented in Section 4 per YMP procedural 
requirements and guidance. 
Where possible, technical products and technical information used as direct inputs to support the 
Exclude screening decisions presented in this report have been obtained from controlled source 
documents and references using the appropriate document identifiers or records system accession 
numbers. Sources include, but are not limited to, YMP AMRs, YMP technical reports, and other 
YMP documents and databases. Results of analysis and models cited in this report are drawn 
primarily from supporting YMP AMRs listed in Section 4.1.2.3. 
Other project and external source documents are cited as needed in individual FEP to amplify the 
discussions, but are identified as corroborative or referential in nature and are cited in the Section 
8 reference list, but are not addressed in Section 4. 
Seismic-Related AMRs: For seismic-related FEPs, this report cites the results stated in the 
Probabilistic Seismic Hazard Analyses for Fault Displacement and Vibratory Ground Motion at 
Yucca Mountain, Nevada (or PSHA) (CRWMS M&O 1998 [DIRS 103731]). The PSHA 
presents the ground motion and fault displacement evaluations resulting from the expertelicitation 
process. Data and analysis for seismic ground motions and fault displacement are 
52 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
drawn directly from the PSHA (CRWMS M&O 1998 [DIRS 103731]) or its associated DTN. 
The ground motion hazard curves present the data as the annualized exceedance probability for a 
specified ground motion. The fault displacement hazard curves present the data as probabilities 
of fault displacements at various representative reference points for the repository. 
In cases where DE FEPs are shared, the scope of this report is to provide a quantification of the 
initiating disruptive event. This is particularly germane for FEPs dealing with EBS component 
responses to fault displacement and ground motion events. Table 6-2 provides the list of 
supporting AMRs that describe the seismic events in terms of amplitude, characteristics of 
ground motion, and probability of such events. The fault displacement and ground motion 
outputs developed in the supporting AMRs are used in other supporting AMRs such as Drift 
Degradation Analysis ANL-EBS-MD-0000027 (BSC 2003 [DIRS 162711]) and Seismic 
Consequence Abstraction MDL-WIS-PA-000003 (BSC 2003 [DIRS 161812]), to describe 
potential consequences. 
Table 6-2. Supporting AMRs Used to Quantify Seismic-Related FEPs 
Disruptive Events 
AMRs 
Document Identifier 
Number for 
Document 
Document Identifier 
Number for 
Document 
Supporting TSPASR 
ANL-CRW-GS-000003 
REV 00 
Supporting TSPA-LA 
SameNot Updated 
since there are no 
related changes to the 
PSHA. (CRWMS 2000 
[DIRS 142321]) 
Characterize 
Framework for 
Seismicity and 
Structural Deformation 
at Yucca Mountain, 
Nevada. 
Not Applicable MDL-MGR-GS-000003 
REV 00 
Scope and Objective for TSPALA 
Summarizes the PSHA for the 
Yucca Mountain site. In addition, it 
furnishes indirect support to 
analyses addressing the effects of 
ground motion and fault 
displacement for the postclosure 
period, to an analysis of seismicrelated 
FEPs, and to an evaluation 
of the extent to which the NRC 
subissues and acceptance criteria 
associated with the Seismicity and 
Structural Deformation (SDS) and 
other key technical issues are 
addressed. 
Updates and provides specific 
ground motion time histories for 
postclosure analysis. 
Development of 
Seismic Design 
Ground Motion Inputs 
for a Geologic 
Repository at Yucca 
Mountain, Nevada. 
(BSC 2003 
[DIRS 166274]) 
53 
Igneous-Related AMRs: For volcanic-related FEPs, the Probabilistic Volcanic Hazard 
Analysis for Yucca Mountain, Nevada (or PVHA) (CRWMS M&O 1996 [DIRS 100116]) 
documents the results of an expert elicitation project that provided the technical basis for 
assessing volcanism related hazards. The methods and findings of that expert elicitation serve as 
the basis for evaluating the probability of a dike intersecting the TSPA-LA repository footprint. 
Although results of the expert elicitation focused on hazard, the documentation also contained 
information relevant to the consequence analysis used in the igneous-related AMRs, which 
support the FEPs evaluation. 
ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
In cases where DE FEPs are shared, the scope of this report is to provide a quantification of the 
initiating disruptive event. This is particularly germane for FEPs dealing with the response of 
the EBS components to igneous events. Table 6-3 provides the list of supporting AMRs that 
describe the igneous events in terms of magmatic properties, in-drift conditions, size and spatial 
aspects, and the probability of such events. The in-drift conditions and spatial aspects developed 
in the supporting AMRs are used in Igneous Intrusion Impacts on Waste Package and Waste 
Characterize Framework 
for Igneous Activity at 
Yucca Mountain, Nevada 
Characterize Eruptive 
Processes at Yucca 
Mountain, Nevada 
Dike/Drift Interactions 
Atmospheric Dispersal 
and Deposition of Tephra 
from a Potential Volcanic 
Eruption at Yucca 
Mountain, Nevada 
Number of Waste 
Packages Hit by Igneous 
Form MDL-EBS-GS-000002 (BSC 2003 [DIRS 165002]), to describe potential consequences. 
Table 6-3. Supporting AMRs Used to Quantify Igneous-Related FEPs 
Disruptive Events AMRs 
Document Identifier 
for AMR supporting 
TSPASR 
ANL-MGR-GS-000001 
REV 00 ICN 01 
ANL-MGR-GS-000002 
REV 00 
(Previously Dike 
Propagation Near 
Drifts) 
ANL-WIS-MD-000015 
REV 00 ICN 01 
Not Applicable (see 
Igneous Consequence 
Modeling for the 
TSPA-SR ANL-WISMD-
000017 REV 00 
ICN 02) 
CAL-WIS-PA-000001 
REV 01 
Document Identifier 
Number for 
Document 
Supporting TSPA-LA 
ANL-MGR-GS-000001 
REV 01 
(BSC 2003 
[DIRS 163769]) 
ANL-MGR-GS-000002 
REV 01 
(BSC 2003 
[DIRS 161838]) 
MDL-MGR-GS-000005 
REV 00 
(BSC 2003 
[DIRS 165923] 
MDL-MGR-GS-000002 
REV 00 
(BSC 2003 
[DIRS 161840]) 
ANL-MGR-GS-000003 
REV 00 
(BSC 2003 
[DIRS 161851]) 
Scope and Objective 
Provide TSPA-LA with a 
conceptual model of the igneous 
framework and parameters to 
support probability and 
consequence analysis of the 
Disruptive Events igneous 
scenarios. 
Provide TSPA-LA with 
conceptual models and 
parameters to support analysis of 
the disruptive events volcanic 
eruption modeling case, as well 
as ash redistribution conceptual 
modeling. 
Provide TSPA-LA with an 
improved basis for igneous 
consequence modeling in the 
area of dike propagation and the 
interaction of magma with 
emplacement drifts. 
Provide a stand-alone report to 
document the ash dispersal 
conceptualization, parameterization, 
and calculations, as wells as 
ash redistribution conceptual 
modeling. Provide an improved 
technical basis for using the 
ASHPLUME code to model 
volcanic ash dispersal for the 
volcanic eruption modeling case 
for TSPA-LA. Provide 
ASHPLUME input parameters for 
implementing ASHPLUME in the 
GoldSim code. 
Provide calculation documenting 
the number of waste packages 
hit by igneous intrusion. Provide 
input parameters to the TSPA 
model. 
Intrusion 
ANL-WIS-MD-000005 REV 01 54 Features, Events and Processes: Disruptive Events 
6.1.4 Assumptions and Simplifications, Alternative Conceptual Models, and 
Consideration of Uncertainty in FEP Screening 
The generic assumption (Assumption 5.1) used in the DE FEPs evaluation is provided in 
Section 5, along with the justification and description of its use. No other assumptions or 
simplifications are used directly in the FEP analyses unless specifically described in the 
individual FEPs discussions. 
Specific guidance and criteria for alternative conceptual model considerations (and their 
relationship to FEPs) and the treatment of uncertainty were addressed, as appropriate, following 
guidance outlined in Section 5 and Appendices A and C of the SPGM (BSC 2002 
[DIRS 160313]). The issues of alternative conceptual models and uncertainty are addressed in 
the supporting documentation cited as part of the FEP evaluation. For included DE FEPs, these 
alternative conceptual models are then incorporated, or not, into the TSPA-LA model based on 
their development and evaluation in the supporting AMRs. For excluded DE FEPs, the 
discussions of the alternative conceptual models from the supporting AMRs are cited in the FEP 
discussions. 
The quantification of uncertainty, as described in the SPGM, is not applicable to DE FEPs 
screening because the DE FEP evaluations do not directly address parameter quantification, 
model development, or abstraction. Rather, by default, the FEPs are included, but screening 
process may result in an exclude decision. The decision is, therefore, binary (included or 
excluded). The issue for such binary decisions is one of confidence rather than quantitative 
uncertainty. The measure of confidence in the decision, however, is related to uncertainty in the 
data or information used for the technical basis. How this underlying uncertainty affects the 
confidence in the screening decision and how it is addressed in the DE FEP evaluation is 
discussed below for each of the following screening criteria: low probability, low consequence, 
and by regulation. 
In the case of the low-probability screening arguments, the mean probability of an event (which 
reflects the range in the underlying uncertainty in supporting information) is used for the 
evaluation. For the DE FEPs, the mean probability was based on, or derived from, an 
expert-elicitation process that considered multiple factors and alternative conceptual models. 
Therefore, specific consideration of uncertainty is of concern during the DE FEP screening 
process only if the mean probability of the event is roughly equivalent to the screening criteria of 
10-8, and only if the mean probability is the only basis used to exclude the FEP (i.e., the 
exclusion is not also coupled to a low-consequence argument). If the screening decision is to 
include a FEP into the performance assessment, and the resulting consequence is to be 
probabilistically weighted within TSPA-LA, then uncertainty becomes a potentially important 
consideration in parameter or model development and implementation, per the SPGM 
(BSC 2002, Appendix A [DIRS 160313]). 
In the case of low-consequence arguments, it is important to identify the mechanisms or 
sequence of events that could impact the repository performance and any associated intermediate 
performance measures. Low-consequence arguments can be postulated using either 
worst-case values for the sequence of events or the associated intermediate performance 
measures. If it can be demonstrated that such values have negligible impact on repository 
55 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
performance, then the issue of uncertainty is addressed by the use of the bounding conditions. 
However, the use of low-consequence arguments also is more subject to uncertainties stemming 
from substantiated and reasonable alternative conceptual models. Inherent in the evaluation of 
such alternative conceptual models are a dependence on data, ranges in field observation and, in 
some cases, on modeling results that have associated uncertainties. Thus, for low-consequence 
arguments, consideration of alternative conceptual models and the range in available data and 
results is more extensively discussed than for probability screening arguments. Alternately, 
modeling that considers uncertainty and alternative conceptual models, and shows a minimal 
impact on exposure or other measures that are representative of release of radionuclides to the 
accessible environment, can be used to support the low-consequence argument. In either case 
(use of bounding condition or models that consider uncertainty), the issue of parameter 
uncertainty is not as critical as the consideration of alternative conceptual models (or model 
uncertainty). 
In the case of FEPs exclusion by regulation, uncertainty (as represented by alternative views of 
regulatory meaning and intent, or appropriate regulatory application) cannot be readily 
quantified. Rather, this type of uncertainty is resolved through the regulatory review and 
licensing process. Thus, in the DE FEP discussions, specific citations to the regulations or 
regulatory discussions are provided, and the application of the regulations to DE FEP screening 
is explicitly expressed for the individual FEPs. 
6.1.5 Alternative Approaches, Mathematical Formulations, and Units of Measure 
Alternative approaches/technical methods to the FEP development and screening process used 
by YMP are discussed in The Enhanced Plan for Features, Events, and Processes (FEPs) at 
Yucca Mountain (BSC 2002 [DIRS 158966]). 
In general, FEP screening involves the comparison of the measure of some feature, event, or 
process to some threshold level of probability, or a threshold measure that defines the onset of 
consequence to repository performance. Mathematical and numerical formulations typically are 
used in the supporting AMRs or cited literature to define the measure of the feature, event, or 
process of interest, in order to define the probability of the event or process (e.g., development of 
the seismic hazard curves), and to define the threshold measure for consequence (e.g., change in 
rock properties). Beyond simple calculations (e.g., rate of fault displacement multiplied by the 
time period of interest) described for each FEP, no mathematical and numerical formulations are 
used directly in the DE FEP evaluations. Rather, the FEP evaluations cite supporting 
information for definition of amplitude and probability of events and processes. 
Depending on the FEP evaluated, the units of measure may vary between FEPs and between 
cited source documents. In all cases, the units as they appeared in the cited source are provided 
to allow traceability, and metric equivalents are provided in parentheses for consistency and 
transparency. 
56 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
6.1.6 Model and Software Issues for Previously Developed and Validated Models 
No models were used directly in the FEP evaluations. The results of models and documents 
developed by others are cited as the technical basis in some instances. This cited documentation 
for those model reports provides documentation of the model formulation, consideration of 
uncertainty and consideration of alternative conceptual models. No software beyond that listed 
in Section 3 was used in the development of this analysis. 
6.1.7 Intended Use and Limitations 
The intended use of this analysis report is to provide FEP screening information for a 
project-specific FEP database, and to promote traceability and transparency regarding FEP 
dispositions. Except as previously noted for some instances of shared FEPs, this report is also 
intended to be used as the source documentation, to provide the technical basis and the 
supporting arguments for exclusion of DE FEPs from the TSPA-LA model. For the DE FEPs 
that are designated for inclusion into the TSPA-LA model, the manner in which the FEP has 
been included, the associated list of parameters, and any uncertainty considerations are provided 
in the cited analysis and model reports. 
The results of the FEP screening presented herein are specific to the repository design evaluated 
for TSPA-LA. 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/construct confirmation is required as part of the construction 
process. This design dependency is due in part to the probability of intersection by an igneous 
intrusion being dependent on the repository footprint, size, location, and orientation. 
Additionally, the response of the repository to seismicity (ground motion and fault displacement) 
is dependent on the drift orientation respective to existing features, and the location of 
emplacement drifts with respect to faults or other significant discontinuities. 
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 evaluation. 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 (66 FR 55732 [DIRS 156671]). (see also the requirements stated at 10 CFR 
63.44 and 10 CFR 63.131 (66 FR 55732 [DIRS 156671]). 
6.2 DISRUPTIVE EVENTS FEP EVALUATION AND ANALYSIS 
This report addresses the 20 DE FEPs that are identified for TSPA-LA consideration. 
Section 6.2.1 addresses the FEPs classified and assigned as seismic-related FEPs, and 
Section 6.2.2 addresses the FEPs classified and assigned as igneous-related FEPs. 
57 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
6.2.1 Seismic-Related FEPs 
The following subsections provide the screening decision and technical basis for inclusion and 
exclusion of the following seismic-related FEPs. 
1.2.01.01.0A Tectonic activitylarge scale (Section 6.2.1.1) 
1.2.02.03.0A Fault displacement damages EBS components (Section 6.2.1.2) 
1.2.03.02.0A Seismic ground motion damages EBS components (Section 6.2.1.3) 
1.2.03.02.0B Seismic-induced rockfall damages EBS components (Section 6.2.1.4) 
1.2.03.02.0C Seismic-induced drift collapse damages EBS components (Section 6.2.1.5) 
1.2.03.02.0D Seismic-induced drift collapse alters in-drift thermohydrology (Section 6.2.1.6) 
1.2.03.03.0A Seismicity associated with igneous activity (Section 6.2.1.7) 
1.2.10.01.0A Hydrologic response to seismic activity (Section 6.2.1.8) 
2.2.06.01.0A Seismic activity changes porosity and permeability of rock (Section 6.2.1.9) 
2.2.06.02.0A Seismic activity changes porosity and permeability of faults (Section 6.2.1.10) 
2.2.06.02.0B Seismic activity changes porosity and permeability of fractures (Section 6.2.1.11) 
2.2.06.03.0A Seismic activity alters perched water zones (Section 6.2.1.12). 
As described in Section 6.3.1 of Characterize Framework for Seismicity and Structural 
6.2.1.1 Tectonic ActivityLarge Scale (1.2.01.01.0A) 
FEP Description: 
Descriptor Phrases: 
Screening Decision: 
Screening Argument: 
Large-scale tectonic activity is interpreted for this FEP to refer to tectonism that is expressed at a 
regional scale (1:250,000 or less) and has the potential for broad uplift, subsidence, folding, and 
geothermal effects. These changes would have the potential to alter the groundwater flux 
through the repository and the amount of water contacting EBS components and, thereby, alter 
the performance characteristics of the repository and its engineered components. These changes, 
if they occur at a sufficient rate, could also potentially impact UZ and SZ flow-and-transport 
properties during the repository-performance period (10,000 years), thereby affecting dose and 
radionuclide release to the accessible environment. 
Yucca Mountain is within the Southern Great Basin of the Basin and Range tectonic province. 
Deformation at Yucca Mountain, Nevada (CRWMS M&O 2000 [DIRS 142321]), tectonically, 
the Basin and Range is experiencing extensional strain at a low to moderate rate, with low to 
ANL-WIS-MD-000005 REV 01 
Large-scale tectonic activity includes regional uplift, subsidence, 
folding, mountain building, and other processes related to plate 
movements. These tectonic events and processes could affect repository 
performance by altering the physical and thermohydrologic 
properties of the geosphere. 
Tectonic activity (uplift), Tectonic activity (subsidence) 
ExcludedLow Consequence 
Global- or plate-scale tectonics, ultimately, drive the tectonism at 
the regional scale. Other processes related to tectonic activity, such 
as volcanism, faulting, seismicity, and fracturing, are evaluated as 
separate FEPs. 
58 Features, Events and Processes: Disruptive Events 
moderate historical seismicity. Yucca Mountain is located on the south flank of a large Miocene 
caldera complex. Structurally, the mountain is dominated by subparallel fault blocks that trend 
to the north and dip to the east. The blocks of ash-flow tuff are bounded by typical Basin and 
Range, high-angle, generally west-dipping, normal faults formed by rapid east-west extension 
during the waning phases of Miocene volcanism. Secondary intrablock faults are common. 
Although Basin and Range tectonic structure defines the structural pattern of Yucca Mountain 
blocks, the whole proposed repository area lies within the Walker Lane, a 100-km-wide 
structural belt along the western edge of the Basin and Range province. The Walker Lane is 
characterized by long, northwest-striking and shorter, north-to-northeast-striking, strike-slip 
faults that accommodate much of the early extension in this region. The peak phase of tectonism 
took place 12.7 to 11.6 million years ago (middle Miocene); and the region has since 
experienced declining strain rates. 
By way of corroboration, the current pattern of Quaternary deformation mimics the middle 
Miocene activity; however, at substantially lower rates (Fridrich et al. 1998, pp. 1 and 2 
[DIRS 164051]). At Yucca Mountain, tectonism is evolving westward through episodes of 
activity (inferred from Fridrich 1999, p. 191 [DIRS 118942]). Yucca Mountain is now about 
50 km from the nearest zones of significant present-day tectonic activity in the Great Basin. The 
rate of subsidence appears to have diminished consistently over the last several million years and 
the locus of subsidence due to the waning extension has migrated west of Yucca Mountain 
(inferred from Fridrich 1999, p. 189 [DIRS 118942]; Dixon et al. 1995, p. 765 [DIRS 102793]). 
During that same period, the western part of Crater Flat basin subsided due to the basin 
extending from 18 to 40 percent in 1.1 million years or less. After 11.6 Ma, the rate of extension 
in the basin declined in a roughly exponential manner. The late Quaternary rate of extension is 
less than 1 percent of the initial rate (Fridrich et al. 1998, pp. 1 and 13 [DIRS 164051]), and may 
be as low as 0.1 to 0.2 percent per million years (Fridrich et al. 1998, pp. 19 and 20 
[DIRS 164051]). Although Crater Flat basin remains, technically, active, it is now in a very 
advanced state of decline, according to Fridrich et al. (1998, p. 2 [DIRS 164051]). 
By way of corroboration, the regional tectonic processes that are occurring in the Yucca 
Mountain region proceed at a low rate. Fridrich (1999, p. 190 [DIRS 118942]) indicates that 
across the southern part of the Crater Flat Basin, the northwest-southeast lengthening is 
approximately 0.1 m per thousand years, and also states that the late Quaternary extension rate is 
approximately one-half as great across central Yucca Mountain, and an order of magnitude lower 
across northern Yucca Mountain. Savage et al. (1999 [DIRS 118952]) present an evaluation of 
the rate of strain accumulation at Yucca Mountain, Nevada, for the period from 1983 to 1998, 
and address alternative interpretations indicating higher strain-accumulation rates presented by 
Wernicke et al. (1998 [DIRS 103485]). The very slow, contemporary strain-accumulation rate in 
the Yucca Mountain area (<2 mm/yr) (Savage et al. 1999, p. 17627 [DIRS 118952]; reported as 
principal strain accumulation rate of 2+/-12 nanostrain/year at N87W+/-12o and -22+/-12 
nanostrain/year N03E+/-12) is consistent with the paleoseismic slip rates calculated from 
Quaternary fault-displacement studies. This strain information corroborates the local cumulative 
fault slip rates (used as direct input for this FEP) in the range of 0.0010.03 mm/yr (CRWMS 
M&O 2000, Table 6 [DIRS 142321]). Since uncertainties in strain rates are reflected in 
uncertainties in recurrence and slip rates, uncertainty in the tectonic strain rate is implicitly 
evaluated through the consideration of multiple tectonic models and through uncertainties in the 
59 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
recurrence rates (CRWMS M&O 1998, Sections 7.1.1 and 8.1.3 and Appendix E 
[DIRS 103731]). The resulting hazard curves are used to evaluate FEPs specific to those issues. 
The present extensional-tectonic regime of the Yucca Mountain region does not promote 
significant tectonic uplift and mountain building. Based on the history of the Crater Flat Basin 
as presented in CRWMS M&O 2000 [DIRS 142321] and described above, tectonic subsidence 
due to regional extension is a more likely scenario at Yucca Mountain than uplift. The local 
cumulative fault slip rate is low (0.0010.03 mm/yr; CRWMS M&O 2000, Table 6 
[DIRS 142321]) and subsidence will not perceptibly be advanced in the absence of slip along the 
block-bounding faults. The probability of such movement is reflected in the hazard curves 
presented in the PSHA (CRWMS M&O 1998 [DIRS 103731]) and used in the specific FEP 
evaluations for ground motion and faulting, which have been included. Thus, there is no 
mechanism not already considered (i.e., seismic ground motion and fault displacement) 
stemming from an extensional terrain that would lead to increased exposure or increased release 
of radionuclides to the accessible environment. This aspect of the FEP, therefore, is Excluded 
based on low consequence. 
Folding and deformation at Yucca Mountain due to rollover along faults, which could 
hypothetically affect infiltration rates, is possible, but at a rate governed by rates for fault slip at 
Yucca Mountain. For the Bow Ridge fault, flattening foliations in the faulted tuffs dip steeply to 
the east (20 to 30) into the graben(s) relative to the beds farther west in the unfaulted areas 
(8 to 15) (Day et al. 1996, p. 2-7 [DIRS 124302] referenced in DTN: MO0310INPDEFEP.000 
[DIRS 165880]). From this information, it is inferred that within the past 12 million years, 
rollover has led to a dip-steepening of lithologic units of no more than 20 (or about 1.6 per 1 
million years). Any further rollover is expected to proceed at a rate less than or equal to that of 
the past, resulting in a steepening of less than 2 in one million years. Such a minor change will 
not significantly affect infiltration or groundwater flow characteristics. Given a critical tilting 
angle of approximately 25 (Fridrich et al. 1996, pp. 2-21 and 2-22 [DIRS 105086] referenced in 
DTN: MO0310INPDEFEP.000 [DIRS 165880]), the tuff beds will likely fracture and slip 
before the change in their orientation (i.e., an increase in fold-limb dip associated with rollover) 
becomes a significant factor in determining local percolation. Therefore, the potential for 
increased permeability in hanging-wall rollover segments from fracturing far outweighs the 
significance of matrix permeability in rollover segments. Changes in porosity and permeability 
of the rock matrix, faults, and fractures are further addressed as specific FEPs. The effects of 
fractures on percolation flux are evaluated in the Fault Displacement Effects on Transport in the 
Unsaturated Zone (CRWMS M&O 2000 [DIRS 151953]). Changes in fracture aperture 
confined to fault zones show virtually no effect on transport behavior, and increased fracture 
aperture applied over the entire UZ domain results in effects that are no more significant than 
other uncertainties related to infiltration (CRWMS M&O 2000, Section 7 [DIRS 151953]). 
Uplift and subsidence associated with tectonic extension is an ongoing process in the Yucca 
Mountain region and, therefore, cannot be excluded as low probability-not credible. 
Earthquake-related events (due to ground motion and fault displacement) are specifically 
addressed in Characterize Framework for Seismicity and Structural Deformation at Yucca 
Mountain, Nevada (CRWMS M&O 2000 [DIRS 142321]). Fridrich et al. (1998, pp. 2526 
[DIRS 164051]) discuss the episodic tectonic activity in Crater Flat Basin. However, due to the 
slow rate at which tectonic processes proceed, tectonic activity at Yucca Mountain will not result 
60 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
in localized changes (uplift, subsidence, folding, or geothermal activity) during the repositoryperformance 
period (10,000 years) that would significantly and adversely affect repository 
performance. Additionally, uncertainty in the tectonics of the region was considered and 
incorporated into the hazard curves presented in the PSHA, which are used as a basis for 
evaluating ground motion and faulting. Since uncertainties in strain rates are reflected in 
uncertainties in recurrence and slip rates, the tectonic strain rate is implicitly evaluated through 
the consideration of multiple tectonic models and through uncertainties in the recurrence. 
Therefore, consideration of large-scale tectonic activity with regard to uplift or subsidence is 
excluded because the magnitude of induced changes (i.e., minimal slip rate and rollover as it 
affects infiltration as discussed in the preceding paragraphs) would not significantly affect 
repository performance over at least a 10,000-year period. The related mechanisms of seismic 
ground motion and fault displacement are considered as separate FEPs and are Included in the 
TSPA-LA analysis. Thus, no mechanism is present that has not already been considered 
(i.e., seismic ground motion and fault displacement) as stemming solely from uplift or 
subsidence that would lead to an increased exposure or increased release of radionuclides to the 
accessible environment. This aspect of the FEP, therefore, is Excluded based on low 
consequence. 
With regard to the geothermal regime, Yucca Mountain is now located in an area of moderate 
heat flow in the Southern Great Basin and lies south of the regions of relatively high crustal heat 
flow in the Great Basin (Lachenbruch and Sass 1978, pp. 212 and 246 [DIRS 142990]). The 
advent of basaltic volcanism at about 11 Ma, as described by Crowe et al. (1995, pp. 4-1 and 4-2 
[DIRS 100110]), signals the end of crustal level magmatism near Yucca Mountain. It indicates 
generation of small, discrete batches of basaltic magma at upper-mantle depths (45 to 60 km 
[28 to 36 mi]) that are capable of making their way quickly to the surface (Crowe et al. 1995, 
pp. 5-2 and 5-6 [DIRS 100110]). Only small volumes (<0.5 km3) of basaltic magma have been 
generated in the Yucca Mountain region during the Quaternary (Crowe et al. 1995, p. 5-5 
[DIRS 100110]). The source depth of these magmas is approximately 60 km (Crowe et al. 1995, 
pp. 5-2 and Figure 5.1 [DIRS 100110] referenced in DTN: MO0310INPDEFEP.000 
[DIRS 165880]). 
The existing geothermal gradient could be changed rapidly in the present tectonic setting, but 
only if a large volume of magma were emplaced high in the mid-to-upper crust (at approximately 
5-km in depth) (inferred from Lachenbruch and Sass 1978, pp. 224 and 244 [DIRS 142990]). 
This could bring the Yucca Mountain area to a pre-eruptive state with attendant hot-spring 
activity. However, this would require great extension rates and crustal mobility, a rapidly 
evolving mantle, and subcrustal conditions that involve either a mantle plume hot spot (Parsons 
et al. 1994, p. 83 [DIRS 106479]) or melting of weakened subducting slab (inferred from 
Bohannon and Parsons 1995, p. 957 [DIRS 101865]). 
Given the present tectonic state of Yucca Mountain and the present source of basaltic-magma 
generation at depths around 60 km (Crowe et al. 1995, p 5-2 and Figure 5-1 [DIRS 100110] 
referenced in DTN: MO0310INPDEFEP.000 [DIRS 165880]), it is unlikely that localized 
effects will occur because of basaltic-magma generation. The existing conditions also indicate 
that a significant (i.e., potentially hazardous) increase in geothermal gradient associated with 
tectonic activity would require several million years of evolution. By way of corroboration, after 
61 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
a two-year study, scientists at the University of Nevada Las Vegas (UNLV) concluded that 
hydrothermal water has not invaded the rocks of Yucca Mountain in at least two million years 
(Wilson and Cline 2001 [DIRS 155426]). The study indicates that fluid inclusions within 
minerals found in roughly half of the 155 rock samples collected throughout Yucca Mountain 
were formed at temperatures ranging from 113 to 141F (45 to 60C), and that calcite 
deposited in fractures and voids was not the result of deposition from the upwelling of 
geothermal water. The uranium-lead dating for the study indicates that the two-phase fluid 
inclusions are older than a minimum age of 1.9 million years. More precise age constraints on 
the two-phase fluid inclusions (based on associated dateable material) indicated that the twophase 
fluid inclusions were older than 4.0 to 5.3 million years. The UNLV study concluded that 
mineral precipitation at the site has been stable for at least the last two to three million years and 
is consistent with formation from low temperature, surficial fluids rather than saturation of the 
site by upwelling hydrothermal fluids. 
Because the existing geothermal regime is currently addressed, and because conditions sufficient 
to create or allow a significant change in the regional geothermal regime within the 10,000-year 
performance period are absent, there is no feasible and additional geothermal regime related 
mechanism considered capable of leading to an increased exposure or an increased release of 
radionuclides into the accessible environment. This aspect of the FEP, therefore, is Excluded 
based on low consequence. 
One hypothetical mechanism capable of changing the geothermal regime would be a 
tectonic-related increase in volcanism. Fridrich et al. (1998, pp. 23 and 24 [DIRS 164051]) 
address the relationship between volcanic activity at Yucca Mountain and tectonic regime. 
Although magmatism in the southwestern Nevada volcanic field and regional extension were 
broadly coeval, there is no apparent genetic link, or at least no correlation in relative extent or 
amount of activity (Sawyer et al. 1994 p. 1316 [DIRS 100075]). Details of igneous events as 
they relate to a proposed repository at Yucca Mountain are specifically addressed in 
Characterize Framework for Igneous Activity at Yucca Mountain, Nevada (BSC 2003 
[DIRS 163769]). Furthermore, the PVHA (CRWMS M&O 1996 [DIRS 100116]) documents the 
results of an expert elicitation project that provided the technical basis for assessing hazards 
related to volcanism. The use of tectonic models as they relate to volcanic hazard is summarized 
in the PVHA (CRWMS M&O 1996 [DIRS 100116]). The PVHA serves as the basis for current 
estimates of igneous intrusion probability. Thus, there is no igneous-related mechanism not 
already considered (i.e., increased igneous activity related to tectonic changes) that would lead to 
an increased exposure or an increased release of radionuclides into the accessible environment. 
This aspect of the FEP, therefore, is Excluded based on low consequence. 
TSPA Disposition: Not Applicable 
Related Documents: Characterize Framework for Seismicity and Structural 
Deformation at Yucca Mountain, Nevada ANL-CRW-GS-000003 
(CRWMS M&O 2000 [DIRS 142321]) 
62 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Characterize Framework for Igneous Activity at Yucca Mountain, 
Nevada ANL-MGR-GS-000001 (BSC 2003 [DIRS 163769]) 
Related FEPs: 
FEPs that examine related but distinct, effects and consequences 
Fault displacement damages EBS components (1.2.02.03.0A) 
Seismic ground motion damages EBS components (1.2.03.02.0A) 
Seismic-induced rockfall damages EBS components (1.2.03.02.0B) 
Seismic-induced drift collapse damages EBS components (1.2.03.02.0C) 
Seismic-induced drift collapse alters in-drift thermohydrology (1.2.03.02.0D) 
Igneous intrusion into repository (1.2.04.03.0A) 
Metamorphism (1.2.05.00.0A) 
Hydrologic response to seismic activity (1.2.10.01.0A) 
Hydrologic response to igneous activity (1.2.10.02.0A) 
Seismic activity changes porosity and permeability of rock (2.2.06.01.0A) 
Seismic activity changes porosity and permeability of faults (2.2.06.02.0A) 
Seismic activity changes porosity and permeability of fractures (2.2.06.02.0B) 
Seismic activity alters perched water zones (2.2.06.03.0A) 
FEPs that examine related and similar effects and consequences 
Hydrothermal activity (1.2.06.00.0A) 
Effects of subsidence (2.2.06.04.0A) 
Natural geothermal effects on flow in the SZ (2.2.10.03.0A) 
Natural geothermal effects on flow in the UZ (2.2.10.03.0B) 
Supplemental Discussion: Regional tectonic processes manifest themselves as patterns of 
systematic deformation that involve regional uplift, 
subsidence, folding, faulting, seismicity, igneous activity, or any 
distinctive combination of such processes. 
In any given local area, such as Yucca Mountain, regional activity determines the style and 
recurrence of deformation expressed by local structure. Thus, the style and recurrence of fault 
slip at Yucca Mountain that occurred during the Quaternary approximates the major effects of 
regional tectonic process that will likely be felt at Yucca Mountain for the next several tens or 
hundreds of thousands of years. 
Tectonic Activity: Tectonic activity at a regional scale typically is concentrated in zones or belts 
of ten, to hundreds of kilometers in width (Thatcher et al. 1999, pp. 1714  1715 
[DIRS 119053]), and persists for millions of years. The significant tectonic zones relevant to 
discussion of Yucca Mountain include the eastern California shear zone, located west of the 
Funeral Mountains, and the intermountain seismic belt, located generally north of 37N latitude 
(Savage et al. 1995, p. 20263 [DIRS 104553]). The zones and belts are characterized by 
relatively high geodetic strain rates and recurrent earthquakes (Thatcher et al. 1999, pp. 1714 and 
1715 [DIRS 119053]). In contrast, Yucca Mountain and its setting (i.e., the Crater Flat domain) 
63 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
have a lower geodetic strain rate (Savage et al. 1999, p. 17627 [DIRS 118952]). The low 
geodetic strain rate (Savage et al. 1995, p. 20263 and Figure 9 [DIRS 104553]), and low 
seismicity levels (e.g., Rogers et al. 1987, p. 82 [DIRS 100176]) found in the Crater Flat domain 
suggest that the site area is located in a tectonic domain that may be isolated from the zones of 
high geodetic strain located to the west and to the north. 
The regional tectonic processes that are occurring in the Yucca Mountain region proceed at a 
very low rate, and the rate of regional tectonism has also decreased greatly since late Miocene 
epoch (Fridrich et al. 1998, p. 1 [DIRS 164051]). At Yucca Mountain, tectonism has evolved 
westward through episodes of activity (inferred from Fridrich 1999, p. 191 [DIRS 118942]). The 
current loci of tectonic activity have moved west of Yucca Mountain (inferred from Fridrich 1999, 
p. 189 [DIRS 118942]; and Dixon et al. 1995, p. 765 [DIRS 102793]). Fridrich et al. (1998, p. 26 
[DIRS 164051]) indicate that data synthesized from Quaternary faults in the Crater Flat basin 
suggest that the rate of faulting has varied, typically over an order of magnitude, over cycles of 
hundred of thousands of years during the late Quaternary. 
Based on the geologic history of Yucca Mountain, tectonic changes will occur at rates that are 
insignificant with respect to the repository-performance period (10,000 years), and the changes 
will be episodic. Episodic behavior can involve long time periods as demonstrated by formation 
of Yucca Mountain itself, which including deposition of the tuff layers and block faulting, that 
occurred over a period of approximately 2.5 to 3 million years (inferred from Fridrich 1999, 
pp. 184189 [DIRS 118942]; and Sawyer et al. 1994, p. 1305 [DIRS 100075]). Episodicvolcanic 
behavior is demonstrated by the quiescent period between deposition of the Timber 
Mountain Group and the Paintbrush Canyon Group alone.a period of approximately 
750,000 years (Sawyer et al. 1994, p. 1312 [DIRS 100075]). Deformational processes associated 
with tectonism also can be punctuated by local events such as volcanic eruptions and 
earthquakes, which are considered potentially disruptive events. Igneous and seismic events are 
treated as separate and distinct FEPs in the following sections. 
Uplift and Subsidence: Uplift and subsidence associated with tectonic extension is an ongoing 
process in the Yucca Mountain region. The elevations of landforms (e.g., basins and ranges) in 
the Yucca Mountain region are a direct consequence of tectonic extension that has operated 
within the past 25 million years (e.g., the basins are loci of chronic subsidence, and the ranges 
are loci of uplift or relative stability). For example, Bare Mountain, the range closest to Yucca 
Mountain, has undergone uplift within the 12- to 8-million-year (Ma) interval (Hoisch et al. 
1997, p. 2829 [DIRS 111854]). In this context, uplift is thought to result from either of two 
processes: (1) magmatic inflation of the crust (Smith et al. 1998, Figure 2(B) [DIRS 118967]), or 
(2) detachment faulting (Hoisch et al. 1997, p. 2829 [DIRS 111854]). Neither of these processes 
has affected Yucca Mountain directly, and neither process is thought to have been a factor in 
local deformation within the past 5 million years (as inferred from Fridrich 1999, p. 190 
[DIRS 118942]; Hoisch and Simpson 1993, p. 6822 [DIRS 106162]; Hoisch et al. 1997, p. 2829 
[DIRS 111854]). The present extensional-tectonic regime of the Yucca Mountain region does 
not promote significant tectonic uplift and mountain building. Given the waning effect of 
extension east of Death Valley and south of the intermountain seismic belt at around 37N 
latitude (inferred from Fridrich 1999, p. 191 [DIRS 118942]; and Dixon et al. 1995, p. 765 
[DIRS 102793]), significant uplift at Yucca Mountain is unlikely and could not develop within the 
next few million years. Because significant uplift will not occur during the 
64 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
repository-performance period (10,000 years), uplift will not provide a mechanism for affecting 
groundwater flow; therefore, uplift will not affect exposure to, or release of, radionuclides. 
Accordingly, uplift is Excluded from the TSPA-LA based on low consequence. 
Based on the history of the Crater Flat Basin as presented by Fridrich (1999 [DIRS 118942]), 
tectonic subsidence due to regional extension is a more likely scenario at Yucca Mountain than 
uplift. However, the rate of subsidence appears to have diminished consistently over the last 
several million years, and the locus of subsidence due to the waning extension has migrated west 
of Yucca Mountain (inferred from Fridrich 1999, p. 189 [DIRS 118942]; Dixon et al. 1995, 
p. 765 [DIRS 102793]). During that same period, the western part of Crater Flat basin subsided 
due to the basin extending from 18 to 40 percent in 1.1 million years or less. After 11.6 Ma, the 
rate of extension in the basin declined in a roughly exponential manner, and the late Quaternary 
rate of extension is less than 1 percent of the initial rate (Fridrich et al. 1998, pp. 1 and 13 
[DIRS 164051]), and may be as low as 0.1 to 0.2 percent per million years (Fridrich et al. 1998, 
pp. 19 and 20 [DIRS 164051]). Although the Crater Flat basin remains tectonically active, it is 
now in a very advanced state of decline, according to Fridrich et al. (1998, p. 2 [DIRS 164051]). 
Given projected fault-slip rates on the order of a few tenths of mm/year, subsidence-related 
effects at Yucca Mountain will be minimal. Because subsidence will be minimal during the 
repository-performance period (10,000 years), subsidence does not provide a mechanism that 
significantly affects groundwater flow; therefore, subsidence will not affect dose. Accordingly, 
subsidence is Excluded from the TSPA-LA based on low consequence during the period of 
interest. 
FEPs based on the mechanisms of regional-scale folding, uplift, and subsidence are Excluded 
from the TSPA-LA based on their low consequence. In the interest of specificity however, 
various potential aspects are discussed in additional detail as follows: 
The evaluation of this FEP included consideration of the change in the spatial relationship of the 
repository and the current water table due to a tectonic-related mechanism. If a significant rise in 
the water table were to occur, Crater Flat and Jackass Flats could become areas of springs 
discharge and seasonal ponding, and hypothetically are of concern. The mechanisms for such 
changes to occur could involve: (1) rising of the water level; (2) lowering of the repository; or 
(3) a combination of effects (1) and (2). This consequence is excluded due to the factors 
described in conditions 1, 2, and 3 below. 
(1) Rising of the water level. The vertical distance between the base of the repository and 
the saturated zone is approximately 300 meters. Stuckless et al. (1996, pp. 98-99 
[DIRS 119051]) discuss excursions of the water table in Plio-Pleistocene time, and 
indicate that past water level elevations are estimated to have been about 115 meters 
high or less. They further indicate that neither geologic evidence for these past 
elevations nor hydrologic flow models suggest that the rises in water table in response 
to climate changes similar to those of the past 2 million years would be sufficient to 
threaten the repository horizon in the future. 
These past elevations reflect the effects of wetter climates and greater strain rates than 
currently exist. Climate changes have been considered and are included in the 
TSPA-LA models. Changes in strain rates could, hypothetically also cause an increase 
65 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
in water levels. However, a significant change in rates is extremely unrealistic 
because the horizontal geodetic strain-accumulation rate in the Yucca Mountain region 
is currently low, at approximately <2 mm/yr (Savage et al. 1999, p. 17627 
[DIRS 118952], with the strain reported as a nanostrain/yr rate). Furthermore, 
regional strain patterns indicate waning effects of strain extension east of Death Valley 
(inferred from Fridrich 1999, p. 191 [DIRS 118942]) with minimal changes in strain 
conditions. A rise in water level, or change in head, could also be related to sudden 
changes in the strain conditions due to an earthquake and result in seismic pumping 
(e.g., see Gauthier et al. 1996, pp. 163-164 [DIRS 100447]). This corroborative 
analysis was performed for TSPA-VA to simulate the timing, amplitude, and duration 
of water-table rise, and indicated a maximum and temporary rise of 50 meters within 
an hour of a simulated seismic event (Gauthier et al. 1996, p.164 [DIRS 100447]). 
This mechanism is described more fully for FEP 1.2.10.01.0A (Hydrologic Response 
to Seismic Activity) and has been excluded. 
Based on past geologic evidence as previously discussed and on the current tectonic 
setting, the potential rise in water levels due to tectonic activity alone, can be Excluded 
based on low consequence. This is because the maximum water level evidenced 
occurring in the past 2 million years of 115 meters above present conditions, is 
insufficient to reach the repository level. Thus, there is no effect on radionuclide 
release to the environment due solely to tectonic changes. 
(2) Lowering the repository: Under long-term extension, normal faulting has caused the 
faulted blocks of Yucca Mountain to subside into Crater Flat basin. However, the rate 
of subsidence is proportional to the paleoseismic slip rate, amounting to no more than 
30 meters in a 1 million year period (i.e., the fault slip rate is 0.03 mm/yr through one 
million years). This cumulative displacement (i.e., lowering of the repository) is 
small compared to the distance separating the repository and the water table. Also, 
any subsidence of the repository would likely be matched by additional subsidence of 
the basin. Therefore, cumulative fault offset alone is insufficient to cause the water 
table to approach the repository level, and such conditions would require greater than 
10,000 years to develop, given current rates of fault movement at Yucca Mountain. 
(3) Combination of effects: Even if expected subsidence (3 m in 10,000 years) occurs, the 
accompanying water table rise would need to be on the order of 200 meters for this 
FEP to be of any consequence. Based on geologic evidence as previously discussed, 
and as shown in the discussion regarding water table rise, the maximum increase in 
water table would be no more than 115 meters. So, the distance between the water 
level and the repository would decrease by no more than approximately 120 meters. 
The combined effects of an extremely unlikely maximum water table rise and an 
expected subsidence of 3 meters are insufficient to cause the water table to reach the 
repository level. Even if these two mechanisms were coupled with a seismic event 
(resulting in a temporary 50 meter water table rise, as previously discussed), the water 
table would still remain below the repository level. 
Elevation of the potentiometric surface is influenced by many factors, including terrain relief, 
percolation, and base level. Also, evaluation of this FEP specifically considered the potential for 
66 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
uplift or subsidence to change drainage at the site and, thereby, increase infiltration. Two 
principal controls on drainage development at Yucca Mountain are further discussed: (1) 
tectonic control (i.e., uplift and subsidence), which determines base level and regional slope; and 
(2) climate, which is the most significant factor affecting infiltration rates and which also 
determines stream-gradient adjustments and erosion/sediment transport rates. For purposes of 
this FEP, discussions regarding effects of tectonic processes, stratigraphic control and 
weathering are ignored. 
Infiltration depends on how much water is fed directly into fractured bedrock, either through 
bare bedrock (hill crests) or through basal drainage of saturated colluvium/alluvium. Very high 
rainfalls produce channeled debris flows on colluvial slopes, indicating that these slopes shed 
water efficiently and are not reservoirs for water percolation into the bedrock. Given the rapidity 
of stream-grade adjustment to climate change (as represented by the presence of debris flows), 
percolation flux associated with tectonically-controlled changes in drainage (as previously 
described related to rollover or strata tilting) is not likely influenced significantly by rates of 
tectonic-induced slope change or local base-level subsidence. The change in percolation flux is 
likely to be undistinguishable from the change in infiltration caused by climate change, and 
supports the screening decision based on low consequence. 
Because of the low rates of uplift and subsidence at Yucca Mountain during the 
repository-performance period (10,000 years), tectonic-related changes on infiltration will be 
insignificant due to the percolation-flux effects dominance of possible climate change. 
Therefore, FEPs related to tectonic-induced infiltration changes are Excluded from the TSPA-LA 
based on their low consequence. 
Folding and Deformation: Folding, uplift or subsidence, as used in the FEP description, refers 
to the effects of the tectonic compression or extension processes. Regional compressive stresses 
that could produce uplift or deformation related to subhorizontal (compressive) fold axes have 
not operated in the Yucca Mountain region, or in the entire Great Basin, within the past 
50 million years (i.e., since Sevier orogeny) (inferred from Keefer and Fridrich 1996, pp. 1-12 
and 1-13 [DIRS 106728]). In fact, the Great Basin generally is a region of crustal extension. 
Therefore, compressional folding at Yucca Mountain during the repository performance period 
(10,000 years) is not geologically reasonable, and the probability of compressional folding at 
Yucca Mountain during the repository-performance period (10,000 years) is negligible. 
Deformation of the tuff beds, associated with extension at Yucca Mountain, is expressed chiefly 
as rollover (i.e., the anelastic behavior of the hanging wall proximal to the footwall) (Fridrich 
et al. 1996, pp. 229 [DIRS 105086]). Rollover, rather than being strictly a folding mechanism, 
is a deformation process that accompanies normal faulting of materials exhibiting low elastic 
strength; it requires repeated and significant displacement and sufficient hanging-wall fracturing 
to appreciably reduce its elastic strength. Normal-fault movements at Yucca Mountain also may 
be associated with extension across fault planes. Hanging-wall rollover occurs as the extension 
and vertical displacement occurs along a fault plane, and segments of hanging wall near the fault 
plane fracture and turn down into the fault plane. Consequently, rollover folds at Yucca 
Mountain affect relatively small segments of the downthrown blocks, and the rollover folds are 
typically associated with increased fracturing as the block-bounding fault is approached. The 
rollover segments have been mapped, and the repository design considers this geologic feature. 
67 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Deformation at Yucca Mountain due to rollover is possible, but at a rate governed by rates for 
fault slip at Yucca Mountain. For the Bow Ridge fault, flattening foliations in the faulted tuffs 
dip steeply to the east (20 to 30) into the graben(s) relative to the beds farther west in the 
unfaulted areas (8 to 15) (Day et al. 1996, p. 2-7 [DIRS 124302] referenced in 
DTN: MO0310INPDEFEP.000 [DIRS 165880]). From this, it is inferred that within the last 
12 million years, rollover has led to a dip-steepening of lithologic units of no more than 20 (or 
about 1.6 per 1 million years). Any further rollover is expected to proceed at a rate less than, or 
equal to, that of the past, resulting in a steepening of less than 2 in 1 million years. 
A potential consequence involves tectonic deformation altering the dip of tuff beds and changing 
the percolation flux. This is predicated on the presumption that tuff bed dip constrains 
percolation flux and, on the presumption that flux is primarily controlled by the strata-confined 
matrix permeability, as opposed to flow through fractures. At Yucca Mountain, the potential for 
increased permeability in hanging-wall rollover segments from fracturing far outweighs the 
significance of matrix permeability in rollover segments. Given an approximate 25 critical 
angle of tilting (Fridrich et al. 1996, pp. 2-21 and 22 [DIRS 105086] referenced in 
DTN: MO0310INPDEFEP.000 [DIRS 165880]), the tuff beds will likely fracture and slip 
before the change in their orientation (i.e., an increase in fold-limb dip associated with rollover) 
becomes a significant factor in local percolation flux. Given the low rate of normal-fault activity 
at Yucca Mountain and the small offsets per slip event, any increase in hanging-wall rollover that 
would affect percolation flux is extremely unlikely. Because of the low dips involved, the very 
low folding rates (as expressed through local cumulative slip rates), and the significant influence 
of local fractures in local percolation flux, this FEP is Excluded from the TSPA-LA based on low 
consequence. The effects of fractures on percolation flux are evaluated in the Fault 
Displacement Effects on Transport in the Unsaturated Zone (CRWMS M&O 2000 
[DIRS 151953]). Changes in fracture aperture confined to fault zones show virtually no effect 
on transport behavior, and an increased fracture aperture applied over the entire UZ domain 
results in effects that are no more significant than other uncertainties related to infiltration 
(CRWMS M&O 2000, Section 7 [DIRS 151953]). 
The rate of change in dip is insufficient to lead to a significant change in percolation rates. This 
portion of the FEP (folding and deformation) is, therefore, Excluded based on low consequence. 
Geothermal Effects: Concerns that tectonic changes could induce local geothermal flux or 
convective flow in the saturated zone also are Excluded from the TSPA-LA based on low 
consequence. 
Some of the conditions conducive to geothermal activity (and associated hydrothermal activity) 
previously occurred in the 14-9 Ma interval to form the southwest Nevada volcanic field 
(inferred from Axen et al. 1993, pp. 69-70 [DIRS 101597]). However, the crust at Yucca 
Mountain has been cooling since final eruption of the Timber Mountain caldera, which deposited 
the uppermost volcanostratigraphic unit at Yucca Mountain about 11.4 million years ago 
(Sawyer et al. 1994, Table 1 [DIRS 100075]). Formation of the caldera complex exhausted the 
late Miocene heat source, and the crust has been cooling steadily for the past 9 million years 
(inferred from Crowe et al. 1995, pp. 4-1 and 4-2 [DIRS 100110]). Additionally, Yucca 
Mountain is located in an area of moderate heat flow in the Southern Great Basin and lies south 
of the relatively high crustal heat flow regions in the Great Basin (Lachenbruch and Sass 1978, 
68 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
pp. 212 and 246 [DIRS 142990]). Furthermore, only small volumes (<0.5 km3) of basaltic 
magma have been generated in the Yucca Mountain region during the Quaternary (Crowe et al. 
1995, p. 5-5 [DIRS 100110]). The source depth of these magmas is approximately 60 km 
(Crowe et al. 1995, p. 5-2 and Figure 5.1 [DIRS 100110] referenced in 
DTN: MO0310INPDEFEP.000 [DIRS 165880]). These observations can be interpreted to 
indicate a waning volcanic setting (Crowe et al. 1995, pp. 4-1, 4-2, 5-5, and 5-15 
[DIRS 100110]). 
Silicic volcanism (magmatism) is an early-phase event in the development of crustal features. In 
the Yucca Mountain vicinity, silicic magmatism events ended approximately 11 million years 
ago and are not likely to reoccur during the compliance period, if at all (BSC 2003, Section 6.2 
[DIRS 163769]). Hydrothermal activity is, usually, the cooling stage in a silicic magma 
intrusion. The presence of silica, calcite, and clay vein deposits and mineral replacement 
assemblages indicate the presence of past hydrothermal activity as seen in the Calico Hills and 
along the south flank of Shoshone Mountain. Hydrothermal activity is conspicuous in the Calico 
Hills and along the south flank of Shoshone Mountain, but comparable hydrothermal activity has 
not been identified at Yucca Mountain. The Calico Hills is an intrusion-related dome, but Yucca 
Mountain is located outside the caldera margin, hence it was never near a hydrothermal source 
(BSC 2003, Figure 3 [DIRS 163769]). Deuteric, not hydrothermal, mineral alteration has 
occurred in the Yucca Mountain vicinity. 
An increase in geothermal gradient sufficient to cause convective flow in the saturated zone 
would require a significant change in geologic conditions, and any significant change in regional 
strain rates and orientation at Yucca Mountain would likely be signaled by an increased heat flux 
(Lachenbruch and Sass 1978, p. 224 [DIRS 142990]) and by a prolonged period of seismicity. 
The existing geothermal gradient could, theoretically change rapidly, but only if a large volume 
of magma were emplaced high in the mid-to-upper crust (at approximately 5 km depth) (inferred 
from Lachenbruch and Sass 1978, pp. 224 and 244 [DIRS 142990]). This, hypothetically, could 
bring the Yucca Mountain area to a pre-eruptive state with attendant hot-spring activity. Such a 
scenario would require great extension rates and crustal mobility, a rapidly evolving mantle, and 
subcrustal conditions that involve either a mantle plume hot spot (Parsons et al. 1994, p. 83 
[DIRS 106479]) or melting of weakened subducting slab (inferred from Bohannon and Parsons 
1995, p. 957 [DIRS 101865]). However, such conditions are at odds with the current geologic 
and tectonic setting previously described. 
Given the present and foreseeable tectonic state of Yucca Mountain (slow rate of extension, 
minimal rate of subsidence), the present source of basaltic-magma generation at depths of 
approximately 60 km, and the lack of conditions suitable for hydrothermal activities in the last 
two million years, it is concluded that a potentially significant increase in geothermal gradient 
would require several million years of evolution. Because of the time required for development, 
geothermal-gradient changes do not provide a mechanism sufficient to affect the repository 
performance within the next 10,000 years. Because there would be no affect on repository 
performance, there would be no significant change to the expected dose or release of 
radionuclides. Consequently, this FEP is Excluded from the TSPA-LA based on low 
consequence. 
69 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
FEP Description: 
6.2.1.2 
Fault Displacement Damages EBS Components (1.2.02.03.0A) 
Descriptor Phrases: 
Screening Decision: 
Screening Argument: Not Applicable 
TSPA Disposition: 
For this FEP, the discussion is limited to presenting the probable fault displacements leading to 
the relative offset of drifts (or tunnels). Consequences, and the manner of inclusion, are addressed 
in the model report Seismic Consequence Abstraction (BSC 2003, Sections 6.8.5 and 6.10 
[DIRS 161812]). The following technical basis for inclusion involves a comparison of the fault 
displacement occurring with a 10-8 annual frequency (see Assumption 5.1 of this analysis report 
(ANL-WIS-MD-000005) to various elements of the repository design (i.e., waste 
package-to-drift wall spacing and set-back requirements). The potential for fault displacement 
damage from intra-block faults and features likely to exist within the repository are explicitly 
Included in the TSPA-LA. The repository design serves as the basis for the TSPA-LA model. 
Consequently, other fault displacements are considered to have been implicitly included because 
the displacements are accommodated by design features such as gaps between EBS elements, or 
in the case of the Solitario Canyon fault, by the use of set-back requirements. 
ANL-WIS-MD-000005 REV 01 
A fault intersects drifts within the repository. The fault undergoes 
movement. The EBS components experience related movement or 
displacement such that performance is degraded by such things as 
tilting of components, component-to-component contact, or drip 
shield separation. Or, it could be as significant as failure due to the 
shearing of drip shields and waste packages by virtue of the 
relative offset across the fault, or as extreme as exhumation to the 
surface. 
Fault displacement (drip shield separation), Fault displacement 
(waste package shearing), Fault displacement (floor buckling 
damage to pallet), Fault displacement (floor buckling damage to 
invert), Fault displacement (exhumation) 
[Note: This is a shared FEP. The scope and intent of this report is 
to quantify the amplitude of the event being considered. The full 
technical basis for these shared FEPs is addressed collectively by 
all of the sharing FEP AMRs. Descriptor phrases not addressed or 
only partially addressed in this report are further addressed in the 
sharing FEP AMRs.] 
Included (BSC 2003, Table 4 [DIRS 161812]) 
Faulting is considered to be a potentially disruptive process with 
effects that include sudden relative rock/soil displacements across 
a fault surface (i.e., fault displacement). These effects are 
potentially relevant to the integrity of the repository and are 
Included in the TSPA-LA. Ground motions associated with fault 
displacements and rock fall are addressed under separate FEPs. 
70 Features, Events and Processes: Disruptive Events 
The history of faulting and the nature of fault slip and its structural effects at Yucca Mountain 
are well known (CRWMS M&O 1998 [DIRS 103731]; and Whitney 1996 [DIRS 100188]). In 
situ stress measurements indicate that faults at Yucca Mountain are at the point of failure (Stock 
and Healey 1988, p. 92 [DIRS 101022]; Stock et al. 1985, p. 8705 [DIRS 101027]) suggesting 
that a fault displacement potential should be evaluated. The PSHA provides the results of the 
expert-elicitation process as it applies to probable fault displacements. 
The PSHA (CRWMS M&O 1998, Figures 8.2 through 8.14, and p. 8-7 [DIRS 103731]) 
specifically examines displacements along block-bounding faults (Points 1 and 2), intrablock 
faults (Points 3 through 6 and 9) and for features likely to be found within the repository 
(Points 7 and 8) with various preexisting conditions, including the occurrence of features within 
the intact rock (Points 7d and 8d). These points were chosen to represent the range of conditions 
that may be encountered near or within the repository. Table 6-4 provides the median and mean 
fault displacements for the 10-8 annual-exceedance probability. Although the mean values for 
fault displacements at annual-exceedance probabilities of less than 10-6 are increasingly skewed 
due to uncertainty (compare median values to the mean values), the mean values shown in Table 
6-4 represent a cautious projection of potential fault displacements and are used for the following 
evaluations discussed. 
Annualized Frequency of Exceedance and Displacements for Various Locations Table 6-4. 
within the TSPA-LA Repository Footprint. 
Location 
1. Bow Ridge Fault 
2. Solitario Canyon Fault 
3. Drill Hole Wash Fault 
4. Ghost Dance Fault 
5. Sundance Fault 
6. Unnamed fault west of Dune Wash 
7a. A hypothetical small fault with 2 m of offset, 
located about 100 m east of Solitario Canyon 
Fault 
7b. A hypothetical shear with 10 cm of offset, 
located about 100 m east of Solitario Canyon 
fault 
7c. A hypothetical fracture, located about 100 m 
east of Solitario Canyon fault (no cumulative 
displacement) 
Annual 
Frequency 
Associated 
with 20-cm 
displacement 
7 x 10-6 
2 x 10-5 
9 x 10-7 
7 x 10-7 
4 x 10-7 
8 x 10-7 
1 x 10-7 
N/A <0.1 
N/A <0.1 <1 
N/A <0.1 <0.1 
71 
7d. Intact rock, located about 100 m east of 
Solitario Canyon Fault 
ANL-WIS-MD-000005 REV 01 
Median 
Displacement 
(cm) for 
Postclosure 
10-8 
Mean 
Displacement (cm) 
for 
Postclosure 
Annual Frequency 
10-8 
200 600 
300 >1000 
30 240 
59 160 
9.9 ~145 
20 210 
2.1 ~75 
9 Features, Events and Processes: Disruptive Events 
Table 6-4. Annualized Frequency of Exceedance and Displacements for Various Locations 
within the TSPA-LA Repository Footprint (Continued) 
fault 
Location 
8a. A hypothetical small fault with 2 m of offset, 
located between the Solitario Canyon fault 
and the Ghost Dance fault 
8b. A hypothetical shear with 10 cm of offset, 
located between the Solitario Canyon fault 
and the Ghost Dance fault 
8c. A hypothetical fracture, located between the 
Solitario Canyon fault and the Ghost Dance 
8d. Intact rock, located between the Solitario 
Canyon fault and the Ghost Dance fault 
9 Midway Valley, fracture with no cumulative 
displacement 
Source: Mean values were taken from the cited DTN: MO0004MWDRIFM3.002 [149092] from files 
/displ/tot_haz/s1.frac_mean.gz; ./displ/tot_haz/s2.frac_mean.gz; ./displ/tot_haz/s3.frac_mean.gz; 
./displ/tot_haz/s4.frac_mean.gz; ./displ/tot_haz/s5.frac_mean.gz; ./displ/tot_haz/s6.frac_mean.gz; 
./displ/tot_haz/s7a.frac_mean.gz; ./displ/tot_haz/s7b.frac_mean.gz; ./displ/tot_haz/s7c.frac_mean.gz; 
./displ/tot_haz/s7d.frac_mean.gz; ./displ/tot_haz/s8a.frac_mean.gz; ./displ/tot_haz/s8b.frac_mean.gz; 
./displ/tot_haz/s8c.frac_mean.gz; ./displ/tot_haz/s8d.frac_mean.gz; ./displ/tot_haz/s9.frac_mean.gz.; 
Notes: Zero displacement at Sites 7d and 8d at >10-8 annual frequency is documented in 
DTN: MO0004MWDRIFM3.002 [DIRS 149092]. See also CRWMS M&O 1998 (Section 8.2.1, 
[DIRS 103731]). Some displacement information was scaled from figures presented in the PSHA 
(CRWMS M&O 1998, Figures 8.2 through 8.14, and was stated in the text on p. 8-7 [DIRS 103731] and 
may be approximate. Median and mean values for 10-8 annual frequency were extrapolated from 
CRWMS M&O 1998, Figures 8-3 for Site 2, and median value was extrapolated for Figure 8-5 for 
displacement hazards at Site 4. 
Inclusion of Block-Bounding FaultsThe block-bounding faults include the Bow Ridge fault 
(Point 1) and the Solitario Canyon fault (Point 2). The Bow Ridge fault is located to the east of 
the waste emplacement area, whereas the Solitario Canyon fault parallels and forms part of the 
western repository footprint boundary. At a 10-8 annual-exceedance probability (see Assumption 
5.1), the estimated mean displacements are 6 meters and >10 meters, respectively. 
The use of setbacks is a project requirement for Type I block-bounding faults. The potential 
displacements from the block-bounding faults are implicitly included because the repository 
Annual 
Frequency 
Associated 
with 20-cm 
displacement 
1x 10-7 
N/A <0.1 9 
N/A <0.1 <1 
N/A <0.1 <0.1 
7 x 10-7 
ANL-WIS-MD-000005 REV 01 
Median 
Displacement 
(cm) for 
Postclosure 
10-8 
Mean 
Displacement 
(cm) for 
Postclosure 
Annual Frequency 
10-8 
2.1 ~75 
28 200 
72 Features, Events and Processes: Disruptive Events 
design that is being used as the basis for the TSPA-LA includes set-back requirements, and the 
repository design is part of the technical basis used to evaluate the repository performance. 
In the case of the Bow Ridge fault, the north to northeast trending faults located east of the Ghost 
Dance fault do not intersect the repository footprint and are located sufficiently distant from the 
repository (see following paragraphs addressing fault/fracture relationships) such that set-back 
requirements are inherently satisfied, and explicit consideration within the TSPA-LA is not 
required. This also applies to the intra-block Ghost Dance fault located east of the repository, as 
it does not intersect the waste emplacement area. In the case of the Solitario Canyon fault, 
specific setback requirements have been instituted as part of the design documentation. 
The following applicable criteria for fault setback have been developed based on engineering 
judgment and analyses based on pre-closure criteria. The design criteria for a setback is taken 
from Project Design Criteria Document (Minwalla 2003, Section 4.11.2 [DIRS 161362]) as: 
Establish a minimum 60-m (200-ft) standoff between Type I faults and 
repository emplacement openings. 
By way of corroboration and clarification, this is noted in 800-P0C-MGR0-00100-000-00E 
(BSC 2003, Sections 7.1.3 and 7.3.1 [DIRS 165572]), which is quoted as follows (with WP in 
the quote meaning waste package): 
It is conservatively estimated that a 60-meter (197 foot) standoff from the 
trace of any Type I fault is adequate to reduce the impact of potential fault 
movement. This standoff considers potential fractured ground in proximity 
of the Type I fault and uncertainty as to where the fault is located at depth. 
The use of a 60-meter (197-foot) standoff for a LA design is conservatively 
applied. 
In the event that the standoff from repository openings to a Type I fault is 
waived following a site impact analysis, a standoff must be maintained 
between Type I faults and any WP. A standoff must be maintained between 
splays associated with Type I faults and any WP. Areas that contain Type I 
faults should be avoided but, if unavoidable, they must be allowed for in 
engineering design. It is conservatively estimated that a standoff from the 
edge of the Type I fault or fault zone by 15 meters (49-feet) is adequate to 
reduce the impact of potential fault movement. Using a 15-meter (49-foot) 
standoff to establish useable drift length for the LA design is conservatively 
applied. 
For YMP, this means that no packages will be placed closer than 60 meters to the main trace of 
the Solitaro Canyon fault unless a specific site impact analysis is performed. Consequently, the 
potential for displacements between the fault and 60 meters need not be explicitly included for 
postclosure considerations as no waste packages or drip shield will be present in that interval. 
The footprint and location of the waste emplacement area, determined in part by the set-back 
requirements, serves as part of the basis for evaluating repository performance. Consequently, 
73 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
the effects of displacement from the Solitario Canyon fault are implicitly addressed in the 
TSPA-LA. 
In support of setback requirements use, conclusions from Sweetkind et al. (1997, pp. 67 to 71 
[DIRS 100183]) suggest that faulting and fracturing are spatially related. Spatial relationships 
based on the results of underground fault mapping have led to the definition/description of zones 
of influence around faults based on the observation that fracture frequency generally increases as 
faults are approached. The consideration of the zone of influence near faults is important 
because it helps define the potential for displacements in the drifts on either side of a fault/drift 
intersection, which determines in part, the number of waste packages that could potentially be 
affected. 
The first conclusion from the study is that mapping results have shown that widths of zones of 
influence are generally quite narrow, ranging from less than 1 meter to about 7 meters from 
faults. The second conclusion is that the width of the zone of influence in the immediate vicinity 
of a fault generally correlates with the amount of cumulative fault offset. Therefore, faults 
having the largest potential future displacement are the most likely to influence the repository 
block. For instance, in the Solitario Canyon fault zone in the ECRB Cross Drift, the total 
displacement is approximately 260 meters, but the gouge and brecciated zones are limited to less 
than 20 meters (Mongano et al. 1999 pp. 59-65 [DIRS 149850]). Faults having tens of meters of 
cumulative offset (e.g., faults at ESF Stations 11+20, 67+88, and 70+58) have zones of influence 
that range up to 10 meters wide. 
Intrablock faults, mentioned in the following discussion, having very small amounts of existing 
cumulative offset (1 to 5 m) have zones of influence that are 1 meter to 2 meters wide. The 
evaluation of the potential for damage from intrablock faults described takes into account the 
observations that gouge and brecciated zones are present only in limited proximity to fault 
planes. 
Inclusion of Intrablock Faults and Features Likely to Be Found in the Repository  
The intra-block faults are mapped features that intersect the repository footprint area. They 
include, but are not limited to, the Drill Hole Wash fault (Point 3), the Ghost Dance fault 
(Point 4), the Sundance Fault (Point 5), an unnamed fault west of Dune Wash (Point 6) and the 
Midway fault (Point 9). Because of the orientation and location of the Drill Hole Wash fault, the 
estimated displacements are used as an analog for possible displacement along the additional 
intrablock Pagany Wash fault and Sever Wash fault, which transect the northeast portion of the 
repository footprint. At a 10-8 annual-exceedance probability (see Assumption 5.1), the 85th 
fractile and mean fault displacements for intrablock faults are, with one exception, less than or 
equal to 2 meters. The exception is for the mean fault displacement of the Drill Hole Wash fault, 
which is approximately 2.5 meters. 
Additionally, features that are likely to be found within the repository are represented in the 
PSHA using a fixed location within the repository, but with hypothetical existing characteristics 
(Points 7 and 8). The PSHA (CRWMS M&O 1998, Figures 8.8 through 8.13 [DIRS 103731]) 
addresses such features within the waste-emplacement area by assessing the probability of 
displacement along existing small faults, shears, and fractures, as represented in the PSHA for 
Points 7a, 7b, 7c, 8a, 8b, and 8c and as explained in Table 6-4. The mean 10-8 
74 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
annual-exceedance probability for these small faults, shears, and fractures is slightly less than 
1 meter, 10 cm, and <1 cm, respectively. The PSHA (CRWMS M&O 1998, p. 8-7 
[DIRS 103731]) also examines the probability of displacement in the intact rock (Points 7d and 
8d) at these hypothetical locations, and indicates that there is only a very unlikely probability 
(<10-8 annual-exceedance probability) that movement greater than 0.1 cm will occur in the intact 
rock. The potential for displacement in the intact rock is inferred analogous to the creation of 
new faults and fractures. 
Based on the intrablock faults and the features likely to exist within the repository, the scale of 
displacements considered ranges from about 2.5 meters to <0.001m (for the intra-block faults 
and the features likely to be found in the repository, respectively). To determine whether this 
range of displacements is significant to repository performance, they are compared to the spatial 
gaps between various EBS components. The results of such a gap analysis are found in Tables 
20 and 21 of the Seismic Consequence Abstraction (BSC 2003 [DIRS 161812]). The gap 
analysis is based on the drawings and design documents listed in Table 1 of that document. 
The analysis shows that most all of the waste packages (with the exception of the naval and 
defense high level waste (DHLW) packages) would remain undamaged even for the 10-8 
annual 
frequency fault displacement at locations 7a, b, c and 8a, b, c. This is because the maximum 
displacement for any of these sites (75 cm for Site 7a and 7b) is always less than the available 
clearances and maximum allowable displacements shown in the seismic consequence model 
report (BSC 2003, Tables 20 and 21 [DIRS 161812]). However, the waste packages containing 
Naval fuels or DHLW would potentially fail when placed over a small displacement fault 
(designated 7a and 8a). Several of the waste package designs also could potentially fail due to 
fault displacement for hazards near the 10-8 
per year level if they are directly over any of the four 
known faults (Drill Hole Wash, Sundance, Pagany Wash, and Sever Wash) intersecting the 
emplacement drifts. 
The actual response of the EBS components to a fault displacement scenario, however, is 
complicated. As a conservative simplification, the fault displacement is analyzed in TSPA-LA 
by considering: (1) the fault as perpendicular to the tunnel axis with the displacement being 
purely vertical, and (2) that the fault displacement occurs at a discrete point, creating a knifeedge 
discontinuity. As previously described, studies of the repository suggests that much of the 
strain will be mechanically dissipated within or near the fault planes. For example, the Dune 
Wash fault (as exposed in the ESF) exhibits a cumulative offset of 65 meters, but the zone of 
increased fracture frequency near the fault is only 6 meters to 7 meters wide (Sweetkind et al. 
1997, Table 21 [DIRS 100183]). A second example is the Sundance fault in the ECRB Cross 
Drift. The Sundance fault has a presumed, though indeterminate, displacement of several 
meters. However, the footwall rock is intact at a distance of only 10 cm from the fault plane. 
The hanging wall of the Sundance fault is slightly more fractured, having an intensely fractured 
zone about 1 meter thick (Mongano et al. 1999, pp. 52-54 [DIRS 149850]). 
The evaluation of potential damage due to fault displacement near fault zones is further evaluated 
and Included in the TSPA-LA analysis as described in Sections 6.8.5 and 6.10 of Seismic 
Consequence Abstraction (BSC 2003 [DIRS 161812]). In general, the expected number of 
damaged waste packages on four secondary faults is evaluated for displacements corresponding 
to a range of annual exceedance frequencies, based on the mean hazard curves for the Sundance 
75 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Fault, the Drill Hole Wash Fault, the Pagany Wash Fault, and the Sever Wash Fault. The 
evaluation considers the clearances between various types of waste packages and the drip shield, 
and on the expected numbers of waste packages that lie on these four faults. Furthermore, the 
potential for DLHW packages to be placed where existing, previously unknown features exist is 
also incorporated into the analysis on a probabilistic basis. Damage to the waste package is 
sampled from a uniform distribution with a lower bound of no damage and an upper bound given 
by the area of the waste package lid. The uniform distribution is a simple approximation to the 
upper and lower damage bounds in lieu of detailed structural response calculations. The upper 
bound is a reasonable estimate for a severely crimped waste package that loses its lid due to 
welds holding the lid in place cracking. The lower bound is a reasonable estimate for a waste 
package that is minimally damaged, either because fault displacement slightly exceeds the 
available clearance or because the package shear occurs at the opposite end of the waste package 
from the lid. 
The FEP description also mentions the extreme case of fault displacements leading to waste 
exhumation. The probabilistically determined mean displacements (less than or equal to 10 
meters for an individual event) are either implicitly or explicitly included in the TSPA-LA, as 
previously described, and define the potential for single-event movements to occur in a 10,000- 
year period and damage the waste packages. The potential for exhumation to occur due to fault 
movement is not credible given the existing cumulative displacement rate of 0.001-0.03 mm/yr 
(CRWMS M&O 2000, Table 6 [DIRS 142321]) or less than 0.3 meters in 10,000-years. The 
depth of the repository below the surface is on the order of 200 meters or greater. Generally 
speaking, the surface elevation of the repository decreases eastward. The elevation along the 
eastern edge of the repository, with the exception of topographic relief in drainages and washes, 
is on the order of 1250 to 1280 meters (4,100 to 4,200 ft). Drawing 800-IED-EBS0-00401-000- 
00C [DIRS 162289], in comparison to Figure 1 of BSC 2002 [DIRS 159124], indicates that the 
easternmost drifts are in the area of lowest ground surface elevations and include drifts 2-1E 
through 2-19E. Drawing 800-IED-EBS0-000402-000-000-00B [DIRS 161727] indicates that the 
endpoint elevations for these drifts varies from 1042 meters for Drift 2-1E, to as high as 1063 
meters for Drift 2-19E. This suggests a difference in elevation (or depth to the repository) of 208 
meters to 238 meters. A more detailed analysis can be had by scaling the end-points of the drifts 
from the grid presented in Drawing 800-IED-EBS0-00401-000-00C [DIRS 162289] and 
subtracting the corresponding end-drift elevations from the nearest topographic grid point 
provided in DTN: MO0002SPATOP00.001 [DIRS 152643]. The northernmost and 
southernmost drifts (Drifts 2-1E and 2-19E) were selected based on minimum and maximum 
drift elevations in the eastern part of the repository, and Figure 5 and DTN: 
MO0002SPATOP00.001 [DIRS 152643] were inspected to determine where the deepest draw 
and lowest elevation of the topographic grid occurred within the repository footprint (Drift 12-E) 
(see Table 6-5 in Section 6.2.2.4 of this report (ANL-WIS-MD-00005 REV 01). A minimum 
value of 211 meters was calculated and is corroborated by a value of 215 meters of overburden 
above the waste emplacement area as indicated in 800-P0C-MGR0-00100-000-00E (BSC 2003, 
Section 7.1.8 [DIRS 165572]). The calculated minimum value could be in error by as much as 
10 meters, as it is based on only the three selected points. Regardless of the exact minimum 
value of overburden, the included fault displacements of 0.3 meter in 10,000-years are clearly 
insufficient to exhume waste to the ground surface within a 10,000-year period. 
76 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
In summary, the potential for fault displacement to damage EBS components has been examined. 
In the case of block-bounding faults and faults existing outside of the waste emplacement area, 
the potential displacement is implicitly included in the design, and the repository footprint is 
used as the basis for the TSPA-LA evaluation. The potential for damage from intrablock faults 
and features likely to exist in the repository have been explicitly included in the TSPA-LA 
model. 
Related FEPs: 
FEPs that examine related but distinct effects and consequences 
Tectonic activitylarge scale (1.2.01.01.0A) 
Seismic ground motion damages EBS components (1.2.03.02.0A) 
Seismic-induced rockfall damages EBS components (1.2.03.02.0B) 
Seismicity associated with igneous activity (1.2.03.03.0A) 
FEPs that examine similar effects and consequences 
Mechanical impact on waste package (2.1.03.07.0A) 
Mechanical impact on drip shield (2.1.03.07.0B) 
Mechanical degradation of pallet (2.1.06.05.0A) 
Mechanical degradation of invert (2.1.06.05.0B) 
Floor buckling (2.1.07.06.0A) 
Related Documents: 
Supplemental Discussion: None 
6.2.1.3 Seismic Ground Motion Damages EBS Components (1.2.03.02.0A) 
FEP Description: 
Descriptor Phrases: 
ANL-WIS-MD-000005 REV 01 
Seismic activity causes repeated vibration of the EBS components 
(drip shield, waste package, pallet, and invert). This could result in 
severe disruption of the drip shields and waste packages through 
vibration damage or contact between EBS components. Such 
damage mechanisms could lead to degraded performance. 
Seismic ground motion (drip shield separation); Seismic ground motion 
(drip shield vibration); Seismic ground motion (drip shield stress corrosion 
cracking); Seismic ground motion (waste package vibration and 
dislodgement); Seismic ground motion (waste package stress corrosion 
cracking); Seismic ground motion (drip shield contacts waste package); 
Seismic ground motion (cladding damage); Seismic ground motion (invert 
damage); Seismic ground motion (ground support damage) 
77 
Seismic Consequence Abstraction 
MDL-WIS-PA-000003 (BSC 2003 [DIRS 161812]) 
Characterize Framework for Seismicity and Structural 
Deformation at Yucca Mountain, Nevada 
ANL-CRW-GS-000003 (CRWMS M&O 2000 [DIRS 142321]) Features, Events and Processes: Disruptive Events 
[Note: This is a shared FEP. The scope and intent of this report is 
to quantify the amplitude of the event to be considered. The full 
technical basis for these shared FEPs is addressed, collectively, by 
all of the sharing FEP AMRs. Descriptor phrases not addressed or 
only partially addressed in this report are further addressed in the 
sharing FEP AMRs.] 
Included (BSC 2003, Table 4 [DIRS 161812]) Screening Decision: 
Not Applicable Screening Argument: 
TSPA Disposition: Ground motion associated with seismic activity has the potential to 
disrupt the integrity of components of the EBS or waste packages. 
These events could lead to impaired container performance and/or 
breaching, with subsequent radionuclide release. Seismic ground 
motion damage is included in the TSPA-LA using damage areas on 
EBS components based on vibratory ground motions at 5  10-4 
per year, 10-6 per year, and 10-7 per year levels. 
The ground motion hazard curves developed for the PSHA were extended to address ground 
motion during the postclosure period as documented in DTN: MO03061E9PSHA1.000 
[DIRS 163721]. The seismic time histories contained in the following DTNs were developed 
starting with the results of the PSHA (CRWMS M&O 1998 [DIRS 103731]) and take into 
account the effect of the upper 300 meters of rock/soil at the site (site response). These 
repository-level inputs for postclosure seismic evaluations are presented in Development of 
Earthquake Ground Motion Input for Preclosure Seismic Design and Postclosure Performance 
Assessment of a Geologic Repository at Yucca Mountain, Nevada (BSC 2003 [DIRS 166274]). 
The ground motion time histories were developed for 5  10-4, 10-6 and 10-7 annual exceedance 
probabilities (see Assumption 5.1 of this report, ANL-WIS-MD-000005 REV. 01) and have been 
used in various seismic-related AMRs to provide inputs to support the postclosure analyses of 
damage to EBS components from seismic ground-motion, seismic-induced rockfall, and the 
effects related to seismic-induced drift collapse. The outputs include, but are not limited to: 
MO0211AVTMH107.001. Acceleration, Velocity, and Displacement Spectrally 
Conditioned Time Histories for the Repository Level at 10-7 Annual Exceedance 
Frequency ([DIRS 161513]) 
MO0301TMHIS106.001. Acceleration, Velocity, and Displacement Time Histories for 
the Repository Level at 10-6 Annual Exceedance Frequency ([DIRS 161868]) 
MO0211TMHIS104.002. Acceleration, Velocity, and Displacement Time Histories for 
the Repository Level at 5x10-4 Annual Exceedance Frequency [DIRS 161540]). 
The outputs are of particular interest because they are used by the Drift Degradation Analysis 
(BSC 2003 [DIRS 162711]) to determine rockfall and drift-collapse effects related to 
seismic-induced ground motion, which are each addressed in related FEPs. 
78 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Additionally the following outputs were used to determine ground motion damage to EBS 
components: 
MO0212AVDSC106.000. Acceleration, Velocity, and Displacement Spectrally 
Conditioned Time Histories for the Repository Level at 10-6 Annual Exceedance 
Frequency [DIRS 164206] 
MO0303DPGVB106.002. Design Peak Ground Velocity for the Repository Level 
(Point B) at 10-6 Annual Exceedance Probability [DIRS 162712] 
MO0210PGVPB107.000. Design Peak Ground Velocity for the Repository Level 
(Point B) at 10-7 Annual Exceedance Probability [DIRS 162713]. 
The characterization of seismic damage incorporates these and other inputs to determine 
damage-related response surfaces, which is fully discussed in the model report Seismic 
Consequences Abstraction (BSC 2003 [DIRS 161812]). Of particular interest for this FEP are 
the peak ground velocity (PGV) values. The horizontal PGV values have been calculated for the 
10-6 per year and 10-7 per year mean annual exceedance frequencies at the emplacement drifts 
(called Point B in the PSHA). The horizontal PGV value for the 10-6 per year ground motions is 
2.44 m/s (MO0303DPGVB106.002 [DIRS 162712]). The horizontal PGV value for the 10-7 per 
year ground motions is 5.35 m/s (MO0210PGVPB107.000 [DIRS 162713]. 
Damage from seismic events is expressed as a failed area on the surfaces of the waste package, 
the drip shield, and the cladding. Section 6.5.1 of the cited model report addresses waste 
packages, Section 6.6.3 addresses drip shields, and Section 6.7 addresses fuel cladding. In 
general, the model report (BSC 2003 [DIRS 161812]) uses structural response calculations for 
the waste package and drip shield as the basis for predicting failed areas for advective flow and 
transport. The criteria for failure are based on a residual stress threshold of between 80 percent 
and 90 percent of the yield strength for Alloy 22, and of 50 percent of the yield strength for 
Titanium Grade 7. A summary of the damage abstraction from Sections 6.5.1 and 6.6.3 and 6.7 
(BSC 2003 [DIRS 161812]), are given in the following paragraphs: 
Structural analyses for the waste package and drip shield have been performed using a single set 
of vibratory ground motions (with two horizontal components and one vertical component) for 
an annual exceedance frequency of 5  10-4 
per year. The results of these analyses demonstrate 
that the response of the waste package and drip shield are always in the elastic regime for the 
5  10-4 
per year ground motion, with no damage to the structures. For less frequent ground 
motions, however, failed areas occur in response to impact of the waste package on the 
emplacement pallet and to end-to-end impacts of adjacent waste packages. 
Because damage to the waste package is always much less than 100 percent, the failed areas are 
abstracted as a uniform distribution with a lower bound of zero (0) and an upper bound that is a 
function of the PGV. The upper bound of the uniform distribution has been increased to ensure 
conservatism with respect to the lognormal distribution over a PGV range of 1 to 6 m/s. Damage 
to the cladding is also included in the seismic scenario class for TSPA-LA. Structural response 
calculations for end-to-end impacts of adjacent waste packages define the axial loads on fuel 
assemblies. These loads are compared to fuel rod failure criteria based on buckling for various 
79 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
fuel pin designs. Comparison of axial loads with the failure criteria indicates that most, if not all, 
fuel pins will fail under vibratory ground motions at the 10-6 per year and the 10-7 per year levels. 
Cladding however, will not fail from the vibratory ground motion at the 5  10-4 per year level. 
Related FEPs: 
FEPs that examine related but distinct effects and consequence 
Tectonic activitylarge scale (1.2.01.01.0A) 
Fault displacement damages EBS components (1.2.02.03.0A) 
Rockfall (2.1.07.01.0A) 
Drift collapse (2.1.07.02.0A) 
FEPs that examine similar effects and consequences 
Seismic-induced rockfall damages EBS components (1.2.03.02.0B) 
Seismic-induced drift collapse damages EBS components (1.2.03.02.0C) 
Seismic-induced drift collapse alters in-drift thermohydrology (1.2.03.02.0D) 
Seismicity associated with igneous activity (1.2.03.03.0A) 
Mechanical impact on waste package (2.1.03.07.0A) 
Mechanical impact on drip shield (2.1.03.07.0B) 
Mechanical degradation of pallet (2.1.06.05.0A) 
Mechanical degradation of invert (2.1.06.05.0B) 
Floor buckling (2.1.07.06.0A) 
Related Documents: 
Supplemental Discussion: None 
6.2.1.4 Seismic-induced Rockfall Damages EBS Components (1.2.03.02.0B) 
FEP Description: 
Descriptor Phrases: 
ANL-WIS-MD-000005 REV 01 
Seismic activity could produce jointed-rock motion and/or changes 
in rock stress leading to enhanced rockfall that could impact drip 
shields, waste packages, or other EBS components 
Seismic-induced rockfall (drip shield damage); Seismic-induced 
rockfall (drip shield stress corrosion cracking); Seismic-induced 
rockfall (waste package damage); Seismic-induced rockfall (drip 
shield contacts waste package); Seismic-induced rockfall (waste 
80 
Development of Earthquake Ground Motion Input for Preclosure 
Seismic Design and Postclosure Performance Assessment of a 
Geologic Repository at Yucca Mountain, Nevada 
MDL-MGR-GS-000003 (BSC 2003 [DIRS 166274]) 
Drift Degradation Analysis 
ANL-EBS-MD-0000027 (BSC 2003 [DIRS 162711]) 
Seismic Consequence Abstraction 
MDL-WIS-PA-000003 (BSC 2003 [DIRS 161812]) Features, Events and Processes: Disruptive Events 
package dislodgement); Seismic-induced rockfall (cladding 
damage); Seismic effects on rockfall 
[Note: This is a shared FEP. The scope and intent of this report is 
to quantify the amplitude of the event to be considered. The full 
technical basis for these shared FEPs is addressed collectively by 
all of the sharing FEP AMRs. Descriptor phrases not addressed or 
only partially addressed in this report are further addressed in the 
sharing FEP AMRs.] 
Included (BSC 2003, Table 4 [DIRS 161812]) Screening Decision: 
Not Applicable Screening Argument: 
TSPA Disposition: Because of the additional imposed stresses, seismic ground motion 
has the potential to dislodge blocks. This could result in additional 
damage to the drip shields through mechanical impact 
mechanisms, and possibly the waste packages (if the drip shields 
fail) via increased seepage through a damaged or separated drip 
shield and is Included in the TSPA-LA. 
It is anticipated that rockfall occurring within lithophysal zones will result in relatively smaller 
rock fragments with insufficient mass and energy to permanently deform or damage the drip 
shields. Therefore, damage to the drip shield from rockfall in the lithophysal units is neglected 
for TSPA-LA. The following discussion addresses only the potential damage to drip shields 
resulting from the impact of relatively large rock blocks, more likely to occur in nonlithopysal 
zones. The mechanical response of the drip shield to an impact by large rock blocks from the 
nonlithophysal unit has the potential to damage the drip shields ability to act as a flow barrier. 
The abstraction for the percent failed surface area mode is included as a function of peak ground 
velocity. An en masse fall of rock fragments, for FEPs purposes, constitutes drift collapse. 
Seismic-induced drift collapse is addressed as FEP 1.2.03.02.0C in Section 6.2.15 of this 
analysis report (ANL-WIS-MD-000005 REV 01). 
The ground motion hazard curves developed for the PSHA (CRWMS M&O 1998 
[DIRS 103731]) were extended to address ground motion during the postclosure period as 
documented in DTN: MO03061E9PSHA1.000 [DIRS 163721]. The seismic time histories 
contained in the following DTNs were developed starting with the results of the PSHA and take 
into account the effect of the upper 300 meters of rock/soil at the site (site response). The 
repository-level inputs for postclosure seismic evaluations are presented in Development of 
Earthquake Ground Motion Input for Preclosure Seismic Design and Postclosure Performance 
Assessment of a Geologic Repository at Yucca Mountain, Nevada (BSC 2003 [DIRS 166274]). 
The ground motion time histories were developed for 5  10-4, 10-6 and 10-7 annual exceedance 
probabilities (see Assumption 5.1 of this report, ANL-WIS-MD-000005 REV. 01) and have been 
used in various seismic-related AMRs to provide inputs to support postclosure analyses of 
damage to EBS components from seismic ground-motion, seismic-induced rockfall, and effects 
related to seismic-induced drift collapse. The outputs include, but are not limited to: 
81 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
MO0211AVTMH107.001. Acceleration, Velocity, and Displacement Spectrally 
Conditioned Time Histories for the Repository Level at 10-7 Annual Exceedance 
Frequency ([DIRS 161513]) 
MO0301TMHIS106.001. Acceleration, Velocity, and Displacement Time Histories for 
the Repository Level at 10-6 Annual Exceedance Frequency ([DIRS 161868]) 
MO0211TMHIS104.002. Acceleration, Velocity, and Displacement Time Histories for 
the Repository Level at 5x10-4 Annual Exceedance Frequency ([DIRS 161540]). 
These outputs are of particular interest because they are used by the Drift Degradation Analysis 
(BSC 2003 [DIRS 162711]) to determine rock block size, rockfall frequency, and drift-collapse 
effects related to seismic-induced ground motion, which are addressed in related FEPs. The 
outputs of that analysis are used to evaluate damage to EBS components from seismically 
induced rockfall, which is included in the seismic scenario class for TSPA-LA. 
In general, vibratory ground motions can cause failure of the host rock around the emplacement 
drifts. The characterization of seismic damage is addressed using damage-related response 
surfaces and is fully discussed in the model report Seismic Consequences Abstraction 
(BSC 2003, Section 6.6 [DIRS 161812]). Damage to the drip shield from impact of individual 
rock blocks is determined by structural response calculations. The objective of these calculations 
is to determine the drip shield areas where the residual stress exceeds the threshold value 
(50 percent of yield strength) for Titanium Grade 7. The analysis evaluates damage based on six 
representative rock sizes impacting the drip shield from three different angles: (1) vertically 
downward onto the top of the drip shield; (2) at a 60 angle (with the horizontal) onto the 
transition region between the top and side of the drip shield; and (3) horizontally into the side 
wall. 
For the 5  10-4 
per year ground motion, tunnels in the lithophysal zones have no damage for 
higher values of rock compressive strength and exhibit only minor damage (but no collapse) at 
the lowest level of compressive strength (BSC 2003, Section 6.4.1.1 [DIRS 162711]). Rockfall 
in the lithophysal zone was also examined for less frequently occurring ground motions. In the 
lithophysal zones, average joint spacing is less than 1 meter, and at certain locations this spacing 
is much smaller, on the order of 0.1 meter (BSC 2003, Section 6.1.4.1 [DIRS 162711]). Based 
on the results of Table 12 of the seismic abstraction model report (BSC 2003, Section 6.6.1.2 
[DIRS 161812]), consider a fragment that (for simplicity) is a cube 0.1-meter (4-in) on a side. 
The volume of this fragment is 0.001 m3 
and its mass is approximately 2 kg, assuming a tuff 
density of approximately 2,000 kg/m3. The velocity of this fragment is 7.7 m/s for a 3-meter 
drop under gravitational acceleration, and the associated kinetic energy is 59 Joules. Table 12 
shows that a 0.11 MT rock with 42 J of kinetic energy does not produce a failed area on the 
surface of the drip shield. A comparison of the mass and kinetic energy of the 0.1-meter 
fragment with the block in Table 12 indicates that there should be no damage from the impact of 
this fragment on the drip shield. A cubic fragment that is 0.3-meters (12-in) on a side has a mass 
of 54 kg and a kinetic energy of 1600 Joules. This fragment is approximately equivalent to the 
0.15 MT (150 kg) rock having 902 Joules of kinetic energy noted in Table 12. This rock 
produces no damage for top and side impacts, and very small damage (0.02 percent) for the 
corner impact. Therefore, for the lithophysal unit, the small fragments have little capability to 
82 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
damage the drip shield, because the small mass and energy of the individual fragments cannot 
cause permanent deformation of the drip shield. Damage to the drip shield from rockfall in the 
lithophysal zone is neglected for TSPA-LA on this basis. Furthermore, in the lithophysal zones, 
the rock mass has very low compressive strength and is permeated with void spaces of varying 
size. This weak rock mass is expected to collapse into small fragments under the load imposed 
by a large vibratory ground motion. Consequently, rockfall in the lithophysal zone does not 
damage the waste package and cladding. The waste package and cladding are not damaged 
because the drip shield remains intact until a seismic event occurs, deflecting any rockfall away 
from the waste package. 
Vibratory ground motions also have the potential to eject large, non-lithophysal rock blocks at 
high velocity. Rock blocks are ejected for the 10-6 per year and the 10-7 per year ground motion 
levels; relatively few blocks are ejected at the 5  10-4 per year ground motion level (see BSC 
2003, Section 6.6.1 [DIRS 161812]). As given in Table 13 of BSC 2003 ([DIRS 161812]), the 
mean damage areas for ground motions with 10-6 and 10-7 annual frequency in the 
non-lithophysal are 1.7 percent and 3.4 percent. Maximum values are 32.2 percent and 63.6 
percent, respectively. Clearly, the mechanical response of the drip shield to impact by a large 
rock block in the non-lithophysal zone has the potential to damage the drip shield and impair its 
function as a flow barrier. 
The analysis uses the PGV as a basis for the damage abstraction, with PGV values being taken 
from: 
MO0303DPGVB106.002. Design Peak Ground Velocity for the Repository Level (Point 
B) at 10-6 Annual Exceedance Probability [DIRS 162712] 
MO0210PGVPB107.000. Design Peak Ground Velocity for the Repository Level (Point 
B) at 10-7 Annual Exceedance Probability [DIRS 162713]. 
The abstraction for the percent failed surface area mode as a function of PGV is based on a logtriangular 
distribution. The results of the calculations for PGVs of 2.44 m/s and 5.35 m/s (10-6 
and 10-7 
per year mean annual exceedance frequencies, respectively) have been supplemented by 
an additional point representing the 5  10-5 
per year exceedance frequency with a PGV of 0.55 
m/s (BSC 2003, Section 6.6.1.4 [DIRS 161812]). For this latter case, there is zero damage to the 
drip shield. Thus, the mode is taken to be the same as the lower bound (i.e., 0.001 percent), and 
the fraction of no-failure cases is taken to be 1.0. Furthermore, due to the length of the drip 
shield versus the drift length value used as a basis for the analysis, multiple block impacts are 
shared between multiple drip shields. 
Related FEPs: 
FEPs that examine related but distinct effects and consequence 
Tectonic activitylarge scale (1.2.01.01.0A) 
Fault displacement damages EBS components (1.2.02.03.0A) 
Seismicity associated with igneous activity (1.2.03.03.0A) 
Hydrologic response to seismic activity (1.2.10.01.0A) 
83 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Rockfall (2.1.07.01.0A) 
Drift collapse (2.1.07.02.0A) 
FEPs that examine similar effects and consequences 
Seismic-induced drift collapse damages EBS components (1.2.03.02.0C) 
Seismic-induced drift collapse alters in-drift thermohydrology (1.2.03.02.0D) 
Mechanical impact on waste package (2.1.03.07.0A) 
Mechanical impact on drip shield (2.1.03.07.0B) 
Mechanical degradation of pallet (2.1.06.05.0A) 
Mechanical degradation of invert (2.1.06.05.0B) 
Related Documents: 
Supplemental Discussion: None 
6.2.1.5 Seismic-induced Drift Collapse Damages EBS Components (1.2.03.02.0C) 
FEP Description: 
Descriptor Phrases: 
ANL-WIS-MD-000005 REV 01 
Seismic activity could produce jointed-rock motion and/or changes 
in rock stress leading to enhanced drift collapse that could impact 
drip shields, waste packages, or other EBS components. Possible 
effects include both dynamic and static loading. 
Seismic-induced drift collapse (drip shield damage); 
Seismic-induced drift collapse (drip shield stress corrosion 
cracking); Seismic-induced drift collapse (waste package damage); 
Seismic-induced drift collapse (drip shield contacts waste 
package); Seismic-induced drift collapse (waste package 
dislodgement); Seismic-induced drift collapse (cladding damage); 
Seismic-induced drift collapse (invert damage); Seismic effects on 
drift collapse 
[Note: This is a shared FEP. The scope and intent of this report is 
to quantify the amplitude of the event to be considered. The full 
technical basis for these shared FEPs is addressed collectively by 
all of the sharing FEP AMRs. Descriptor phrases not addressed or 
only partially addressed in this report are further addressed in the 
sharing FEP AMRs.] 
84 
Development of Earthquake Ground Motion Input for Preclosure 
Seismic Design and Postclosure Performance Assessment of a 
Geologic Repository at Yucca Mountain, Nevada 
MDL-MGR-GS-000003 (BSC 2003 [DIRS 166274]) 
Drift Degradation Analysis 
ANL-EBS-MD-0000027 (BSC 2003 [DIRS 162711]) 
Seismic Consequence Abstraction 
MDL-WIS-PA-000003 (BSC 2003 [DIRS 161812]) Features, Events and Processes: Disruptive Events 
ExcludedLow Consequence Screening Decision: 
Screening Argument: The potential consequences of seismic-induced drift collapse 
require two preceding factors: 1) that drift collapse occurs, 
and 2) that the volume or amount of collapse is sufficient to 
cause structural failure of the drip shields. Drift degradation 
analysis covered in the following discussion, indicates that drift 
collapse in the non-lithophysal unit is not of concern. However, 
the analysis does indicate that seismic-induced rockfall in the nonlithophysal 
unit may be of concern due to the rock block size. The 
analysis also demonstrates that drifts in the lithophysal zones 
would collapse under the 10-6 
per year (and by inference the larger, 
10-7 
per year) vibratory ground motions (BSC 2003, Section 6.4.1.1 
[DIRS 162711]). 
The ground motion hazard curves developed for the PSHA (CRWMS M&O 1998 
[DIRS 103731]) were extended to address ground motion during the postclosure period as 
documented in DTN: MO03061E9PSHA1.000 [DIRS 163721]. The seismic time histories 
contained in the following DTNs were developed starting with the results of the PSHA and take 
into account the effect of the upper 300 meters of rock/soil at the site (site response). These 
repository-level inputs for postclosure seismic evaluations are presented in Development of 
Earthquake Ground Motion Input for Preclosure Seismic Design and Postclosure Performance 
Assessment of a Geologic Repository at Yucca Mountain, Nevada (BSC 2003 [DIRS 166274]). 
These ground motion time histories were developed for 5  10-4, 10-6 and 10-7 annual exceedance 
probabilities (see Assumption 5.1 of this report, ANL-WIS-MD-000005 REV. 01) and have been 
used in various seismic-related AMRs to provide inputs to support postclosure analyses of 
damage to EBS components from seismic ground-motion, seismic-induced rockfall, and effects 
related to seismic-induced drift collapse. The outputs include, but are not limited to: 
MO0211AVTMH107.001. Acceleration, Velocity, and Displacement Spectrally 
Conditioned Time Histories for the Repository Level at 10-7 Annual Exceedance 
Frequency ([DIRS 161513]) 
MO0301TMHIS106.001. Acceleration, Velocity, and Displacement Time Histories for 
the Repository Level at 10-6 Annual Exceedance Frequency ([DIRS 161868]) 
MO0211TMHIS104.002. Acceleration, Velocity, and Displacement Time Histories for 
the Repository Level at 5x10-4 Annual Exceedance Frequency ([DIRS 161540]). 
These outputs are of particular interest because they are used by the Drift Degradation Analysis 
(BSC 2003 [DIRS 162711]) to determine rockfall and drift-collapse effects related to 
seismic-induced ground motion, which are addressed in related FEPs. The drift degradation 
analysis for the non-lithophysal unit is presented in Table 33 of that document. The worst-case 
analysis indicates for ground motions occurring at a 10-7 annual frequency, the total volume of 
rockfall is 50.64 m3 with a total of 46 blocks, for each km of drift. The maximum block size, 
without considering small-scale fractures, is 7.36 m3 (BSC 2003, Table 31 [DIRS 162711]). The 
nominal diameter of the drift is 5.5 meters, so each meter of drift length constitutes a volume of 
85 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
15.9 m3. This indicates that drift collapse in the non-lithophysal unit is of no concern. However, 
the analysis does indicate that seismic-induced rockfall in the non-lithophysal unit may be of 
concern due to the rock block size. Seismic-induced rockfall damage is addressed as a separate 
FEP. By comparison, for the lithophysal unit, ground motions with an annual frequency of 10-6 
cause complete collapse of the emplacement drifts (BSC 2003, Section 6.4.1.1 [DIRS 162711]). 
For the 5  10-4 
per year ground motion, tunnels in the lithophysal zones show no damage for 
higher values of rock compressive strength and exhibit only minor damage (but no collapse) at 
the lowest level of compressive strength (BSC 2003, Section 6.4.1.1 [DIRS 162711]). Drift 
degradation analysis also demonstrates that drifts in the lithophysal zones would collapse under 
the 10-6 
per year (and by inference the larger, 10-7 
per year) vibratory ground motions (BSC 2003, 
Section 6.4.1.1 [DIRS 162711]). Consequently, drift collapse in the lithophysal zones can 
impose a static load on the drip shield from the weight of the natural backfill that fills the drifts 
as a result of the collapse. The characterization of seismic damage from rockfall is addressed 
using damage-related response surfaces and is fully discussed in the model report Seismic 
Consequences Abstraction (BSC 2003, Sections 6.6.1 and 6.6.2 [DIRS 161812]). In the 
lithophysal zones, the static loads from a collapsed drift using continuum or discontinuum 
representations of the host rock are not expected to collapse the drip shield. This is predicated on 
the mean value of the rock mass pressure predicted for the drip shield. Damage to the drip shield 
from rockfall in the lithophysal zone is neglected for TSPA-LA on this basis. However, 
structural response calculations have not been performed for the most extreme pressures or for 
the nonuniform loading predicted by the rock mechanics codes. 
TSPA Disposition: Not Applicable 
Related FEPs 
FEPs that examine related but distinct consequences and events 
Tectonic activity.large scale (1.2.01.01.0A) 
Mechanical impact on waste package (2.1.03.07.0A) 
Mechanical impact on drip shield (2.1.03.07.0B) 
Mechanical degradation of pallet (2.1.06.05.0A) 
Mechanical degradation of invert (2.1.06.05.0B) 
Effects of drip shield on flow (2.1.06.06.0A) 
Rockfall (2.1.07.01.0A) 
Drift collapse (2.1.07.02.0A) 
Mechanical effects of excavation/construction in the near field (2.2.01.01.0A) 
Thermally-induced stress changes in the near field (2.2.01.02.0A) 
Rock properties of host rock and other units (2.2.03.02.0A) 
Enhanced influx at the repository (2.1.08.02.0A) 
Focusing of unsaturated flow (fingers, weeps) (2.2.07.04.0A) 
FEPs that examine similar consequences and events 
Seismic-induced rockfall damages EBS components (1.2.03.02.0B) 
Seismic-induced drift collapse alters in-drift thermohydrology (1.2.03.02.0D) 
86 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Related Documents: Development of Earthquake Ground Motion Input for Preclosure 
Seismic Design and Postclosure Performance Assessment of a 
Geologic Repository at Yucca Mountain, Nevada 
MDL-MGR-GS-000003 (BSC 2003 [DIRS 166274]) 
Drift Degradation Analysis 
ANL-EBS-MD-000027 (BSC 2003 [DIRS 162711]) 
Seismic Consequence Abstraction 
MDL-WIS-PA-000003 (BSC 2003 [DIRS 161812]) 
Supplemental Discussion: Degradation of underground openings as a function of time, 
including drift collapse, is a natural and expected occurrence for 
any subsurface excavation. Over time, changes to both the stress 
condition and the strength of the rock mass occur due to several 
different interacting factors. 
With time and changes in the state of stress in the repository block due to stress relief, 
seismic activity, tectonic activity, or thermal loading and unloading, the rock mass 
surrounding the emplacement drifts will deteriorate. A triggering event may cause movement or 
collapse of the drift onto the drip shield and/or waste packages. The drip shield and/or waste 
package may undergo structural failure due to impact or loading and water may flow through the 
breach and transport radionuclides from the repository. 
An analysis of the potential for drift collapse within the repository horizon is provided in the 
Drift Degradation Analysis (BSC 2003 [DIRS 162711]). This document provides an analysis of 
the amount of drift degradation in repository emplacement drifts anticipated for discrete events 
and time increments extending throughout the 10,000-year compliance period for postclosure 
performance. The earlier versions of the Drift Degradation Analysis (Revisions 0 and 1) relied 
primarily on the DRKBA numerical code, which provides for a probabilistic key block 
assessment based on realistic fracture patterns determined from field mapping in the ESF. 
However, the use of the DRKBA code to determine potential rockfall data at the repository 
horizon during the postclosure period had several limitations and exhibited areas for 
improvement. To resolve these limitations, additional numerical codes have been included that 
can explicitly apply seismic and thermal loads, providing significant improvements to the 
analysis of drift degradation and extending the validity of drift degradation models. 
The revised analysis now incorporates diverse factors, including rock mass characterization to 
accommodate differences in lithophysal and non-lithophysal rock types and strength properties, 
seismic ground motion, thermal stresses, and time-dependent degradation of rock strength. The 
analysis now provides a model of the rock mass jointed configuration surrounding the 
emplacement drift cavity, and provides a statistical description of block sizes formed by fractures 
around the emplacement drifts for the lithologic units of the repository host horizon. The 
analysis also provides estimates of changes in drift profiles resulting from progressive 
deterioration of the emplacement drifts and provides an estimate of the time required for 
significant drift deterioration to occur. Specific analysis now include a thermomechanical 
assessment of the repository block at Yucca Mountain to determine thermal stress inputs to the 
87 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
drift degradation models and a fracture degradation assessment to account for long-term strength 
degradation. The analysis also includes a drift degradation structural model for non-lithophysal 
rock that includes thermal and seismic loading and a drift degradation lithophysal model that 
includes thermal and seismic loading. The results of this modeling and analysis activity provide 
rockfall data to support structural analyses of the ground support system, the drip shield, and 
waste package. This assessment provides strength degradation inputs to the drift degradation 
models. The drift degradation analysis also provides the changes in drift profile due to rockfall, 
which supports analyses of seepage into the emplacement drift during the period of compliance 
for postclosure performance. 
6.2.1.6 
Earthquake Ground Motion Input for Preclosure Seismic Design and Postclosure Performance 
Assessment of a Geologic Repository at Yucca Mountain, Nevada (BSC 2003 [DIRS 166274]). 
Seismic-Induced Drift Collapse Alters In-drift Thermohydrology (1.2.03.02.0D) 
FEP Description: 
Descriptor Phrases: 
Screening Decision: 
Screening Argument: 
TSPA Disposition: 
The ground motion hazard curves developed for the PSHA (CRWMS M&O 1998 
[DIRS 103731]) were extended to address ground motion during the postclosure period as 
documented in DTN: MO03061E9PSHA1.000 [DIRS 163721]. The seismic time histories 
contained in the following DTNs were developed starting with the results of the PSHA and 
taking into account the effect of the upper 300 meters of rock/soil at the site (site response). 
Therepository-level inputs for postclosure seismic evaluations are presented in Development of 
ANL-WIS-MD-000005 REV 01 
Seismic activity could produce jointed-rock motion and/or changes 
in rock stress leading to enhanced drift collapse and/or rubble infill 
throughout part or all of the drifts. Drift collapse could impact 
flow pathways within the EBS, mechanisms for water contact with 
EBS components, and thermal properties within the EBS. 
Flow and pathways in collapsed drift, Thermal effects of collapsed 
drift, Seismic-induced drift collapse (invert damage) 
[Note: This is a shared FEP. The scope and intent of this report is 
to quantify the amplitude of the event to be considered. The full 
technical basis for these shared FEPs is addressed collectively by 
all of the sharing FEP AMRs. Descriptor phrases not addressed or 
only partially addressed in this report are further addressed in the 
sharing FEP AMRs.] 
Included (BSC 2003, Table 4 [DIRS 161812]) 
Not Applicable 
The potential consequences of drift collapse require two factors: 
1) that drift collapse occurs, and 2) that the volume or 
amount of collapse is sufficient to changes the drift profile 
such that seepage into the drift and thermal properties are 
significantly affected. Changes to the seepage due to 
seismic-induced changes in the drift profile are Included in the 
TSPA-LA. 
88 Features, Events and Processes: Disruptive Events 
The ground motion time histories were developed for 5  10-4, 10-6 and 10-7 annual exceedance 
probabilities (see Assumption 5.1 of this report, ANL-WIS-MD-000005 REV. 01) and have been 
used in various seismic-related AMRs to provide inputs to support postclosure analyses of 
damage to EBS components from seismic ground-motion, seismic-induced rockfall, and effects 
related to seismic-induced drift collapse. The outputs include, but are not limited to: 
MO0211AVTMH107.001. Acceleration, Velocity, and Displacement Spectrally 
Conditioned Time Histories for the Repository Level at 10-7 Annual Exceedance 
Frequency ([DIRS 161513]) 
MO0301TMHIS106.001. Acceleration, Velocity, and Displacement Time Histories for 
the Repository Level at 10-6 Annual Exceedance Frequency ([DIRS 161868]) 
MO0211TMHIS104.002. Acceleration, Velocity, and Displacement Time Histories for 
the Repository Level at 5X10-4 Annual Exceedance Frequency ([DIRS 161540]). 
These outputs are of particular interest because they are used by the Drift Degradation Analysis 
(BSC 2003 [DIRS 162711]) to determine rockfall and drift-collapse effects related to 
seismic-induced ground motion, which are addressed in related FEPs. As discussed for FEP 
1.2.03.02.0C (Seismic-induced drift collapse damages EBS components), the drift collapse in the 
non-lithophysal unit is of no concern due to limited volume and block size. There is no change 
in the seepage abstraction in the non-lithophysal zones because the rockfall does not completely 
fill the tunnels at the ground motion levels of interest. The seepage abstraction currently 
includes an enhancement factor for limited collapse, and this enhancement factor is deemed 
adequate to address limited collapse in the non-lithophysal zone. 
For the 5  10-4 
per year ground motion, tunnels in the lithophysal zones have no damage for 
higher values of rock compressive strength and only minor damage (but no collapse) at the 
lowest level of compressive strength. However, for the lithophysal unit, ground motions with an 
annual frequency of 10-6 or less (see Assumption 5.1 of this report) cause complete collapse of 
the emplacement drifts (BSC 2003, Section 6.4.1.1 [DIRS 162711]). The collapse of drifts from 
high amplitude ground motion in the lithophysal zones can fill the drifts with rubble, altering the 
hydrologic and thermal environment around the EBS components. Changes in seepage are 
addressed by modifying the seepage flux (BSC 2003, Section 6.9 [DIRS 161812]) for the 
lithophysal zone. 
This FEP is considered as Included in the TSPA-LA and seismic-induced rockfall and change in 
seepage associated with drift collapse are addressed in the TSPA-LA. Changes in the thermal 
properties due to seismic-induced drift collapse are addressed in the sharing FEP AMRs (see 
Section 1.2 of this report, ANL-WIS-MD-000005 REV 01). 
Related FEPs 
FEPs that examine related but distinct consequences and events 
Tectonic activity.large scale (1.2.01.01.0A) 
Mechanical impact on waste package (2.1.03.07.0A) 
89 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Mechanical impact on drip shield (2.1.03.07.0B) 
Mechanical degradation of pallet (2.1.06.05.0A) 
Mechanical degradation of invert (2.1.06.05.0B) 
Effects of drip shield on flow (2.1.06.06.0A) 
Rockfall (2.1.07.01.0A) 
Drift collapse (2.1.07.02.0A) 
Mechanical effects of excavation/construction in the near field (2.2.01.01.0A) 
Thermally-induced stress changes in the near field (2.2.01.02.0A) 
Rock properties of host rock and other units (2.2.03.02.0A) 
FEPs that examine similar consequences and events 
Seismic-induced rockfall damages EBS components (1.2.03.02.0B) 
Seismic-induced drift collapse damages EBS components (1.2.03.02.0C) 
Enhanced influx at the repository (2.1.08.02.0A) 
Focusing of unsaturated flow (fingers, weeps) (2.2.07.04.0A) 
Related Documents: Development of Earthquake Ground Motion Input for Preclosure 
Seismic Design and Postclosure Performance Assessment of a 
Geologic Repository at Yucca Mountain, Nevada 
MDL-MGR-GS-000003 (BSC 2003 [DIRS 166274]) 
Drift Degradation Analysis 
ANL-EBS-MD-000027 (BSC 2003 [DIRS 162711]) 
Seismic Consequence Abstraction 
MDL-WIS-PA-000003 (BSC 2003 [DIRS 161812]) 
Supplemental Discussion: None 
6.2.1.7 
Screening Argument: 
Seismicity Associated with Igneous Activity (1.2.03.03.0A) 
FEP Description: Seismicity associated with future igneous activity in the Yucca 
Mountain region may affect repository performance. 
Seismicity associated with igneous activity Descriptor Phrases: 
[Note: This is a shared FEP. The scope and intent of this report is 
to quantify the amplitude of the event to be considered. The full 
technical basis for these shared FEPs is addressed collectively by 
all of the sharing FEP AMRs. Descriptor phrases not addressed or 
only partially addressed in this report are further addressed in the 
sharing FEP AMRs.] 
Included (BSC 2003, Table 6.4.2 [DIRS 166274]) Screening Decision: 
Not Applicable 
90 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
TSPA Disposition: Seismicity associated with igneous activity was either specifically 
considered, or was considered within the background evaluation of 
ground motion, by expert elicitation teams in developing 
probabilistic ground motion hazards. It is implicitly Included in 
the TSPA-LA. 
Ground motion associated with seismic events has the potential to disrupt the integrity of the 
EBS or waste package components. Repeated vibration of a container and/or container impact 
with other repository elements could potentially cause the container to be damaged. These 
events could lead to decreased performance and/or to radionuclide release. 
At Yucca Mountain, earthquakes associated with igneous activity would be related to basaltic 
intrusion and volcanism. Volcanic eruption is commonly preceded and accompanied by swarms 
of earthquakes that indicate progressive rock-strength failure as magma migrates to the earths 
surface (Smith et al. 1998, p. 158 [DIRS 118967]). That study specifically mentions that magma 
intrusion into the seismogenic crust tends to supplant sizable, large tectonic earthquakes with 
swarms of low to moderate magnitude earthquakes. Smith et al. (1998, Table 1 [DIRS 118967]) 
summarizes published accounts of observed seismicty that is clearly associated with dike 
intrusion and indicate that observational seismicity from volcanic rift zones worldwide indicates 
the mean maximum magnitude of dike-induced earthquakes is 3.8 0.8 and is generally less than 
5 (Smith et al. 1998, Table 1 [DIRS 118967]). That study further list areas where magmatism 
has affected activity of the Basin and Range normal faults including, possibly, the Yucca 
Mountain area of southern Nevada, even though it is not a volcanic rift zone. That study also 
lists two approaches for estimating maximum magnitude of seismicity estimation based on 
ruptured surface area of fissures and faults, and the use of recorded seismicity during dike 
injection events. The first of these methods was considered in the PSHA. 
As stated in Characterize Framework for Seismicity and Structural Deformation at Yucca 
Mountain, Nevada (CRWMS M&O 2000, Section 6.4.4 [DIRS 142321]), The PSHA was 
computed by integrating recurrence curves for earthquakes of Mw 5.0 and greater. It is 
established practice that smaller earthquakes produce no damage to well-engineered structures 
regardless of the ground motion they generate. Seismicity related to volcanic processes, 
particularly basaltic volcanoes and dike injection, was explicitly modeled in the volcanic source 
zones by two of the six expert teams working on the PSHA (as summarized in CRWMS M&O 
2000, Table 5 [DIRS 142321]). Igneous-related earthquakes were not modeled as a separate 
source zone by the four other PSHA expert teams because they presumed that the low magnitude 
and frequency of igneous-related seismicity were accounted for by the areal source zone 
evaluation used for the PSHA. 
The repository-level inputs for postclosure seismic evaluations are presented in Development of 
Earthquake Ground Motion Input for Preclosure Seismic Design and Postclosure Performance 
Assessment of a Geologic Repository at Yucca Mountain, Nevada (BSC 2003 [DIRS 166274]). 
The ground motion time histories were developed for 5  10-4, 10-6 and 10-7 annual exceedance 
probabilities (see Assumption 5.1 of this report, ANL-WIS-MD-000005 REV. 01) and have been 
used in various seismic-related AMRs to provide inputs to support postclosure analyses of 
damage to EBS components from seismic ground-motion, seismic-induced rockfall, and effects 
related to seismic-induced drift collapse. The outputs include, but are not limited to: 
91 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
MO0211AVTMH107.001. Acceleration, Velocity, and Displacement Spectrally 
Conditioned Time Histories for the Repository Level at 10-7 Annual Exceedance 
Frequency ([DIRS 161513]) 
MO0301TMHIS106.001. Acceleration, Velocity, and Displacement Time Histories for 
the Repository Level at 10-6 Annual Exceedance Frequency ([DIRS 161868]) 
MO0211TMHIS104.002. Acceleration, Velocity, and Displacement Time Histories for 
the Repository Level at 5x10-4 Annual Exceedance Frequency ([DIRS 161540]). 
Because seismicity associated with igneous activity is included in the PSHA results, through 
volcanic source zones or areal source zones, all seismic inputs developed to support postclosure 
analyses account for the volcanic component of seismic hazard. Thus, it is inappropriate to 
represent igneous-related seismicity in the TSPA-LA by a parameter or submodel independent of 
the PSHA results. It does not represent a separate mechanism for changing the properties of the 
host rock or for damaging the waste packages. Furthermore, the low-magnitude events 
associated with igneous activity do not represent a credible damage mechanism that could 
contribute to enhanced failure potential of intact waste packages during the 10,000-year 
performance period. Waste package damage due to a related igneous-intrusion is addressed 
separately in FEP 1.2.04.04.0A (Igneous intrusion interacts with EBS components), wherein 
waste packages in intersected drifts are assumed to have failed due to the extreme conditions 
potentially existing in the intersected drifts. Addition of a low-magnitude seismic component 
following failure of waste packages due to intrusion of the drifts would be inconsequential to 
dose. 
Related FEPs: 
FEPs that examine related but distinct effects and consequence 
Fault displacement damages EBS components (1.2.02.03.0A) 
Seismic-induced rockfall damages EBS components (1.2.03.02.0B) 
Igneous intrusion into repository (1.2.04.03.0A) 
Igneous intrusion interacts with EBS components (1.2.04.04.0A) 
Hydrologic response to seismic activity (1.2.10.01.0A) 
FEPs that examine similar effects and consequences 
Seismic ground motion damages EBS components (1.2.03.02.0A) 
Related Documents: 
ANL-WIS-MD-000005 REV 01 
Characterize Framework for Seismicity and Structural 
Deformation at Yucca Mountain, Nevada 
ANL-CRW-GS-000003 (CRWMS M&O 2000 [DIRS 142321]) 
Development of Earthquake Ground Motion Input for Preclosure 
Seismic Design and Postclosure Performance Assessment of a 
Geologic Repository at Yucca Mountain, Nevada 
MDL-MGR-GS-000003 (BSC 2003 [DIRS 166274]) 
92 Features, Events and Processes: Disruptive Events 
Supplemental Discussion: None 
6.2.1.8 Hydrologic Response to Seismic Activity (1.2.10.01.0A) 
FEP Description: 
Descriptor Phrases: 
Screening Decision: 
Screening Argument: 
Seismic activity is the result of sudden fault slip, and can cause changes in rock stresses or 
changes in flow through the drifts. The change in the state of stress, in turn, has the potential to 
affect the groundwater flow and the transport properties of the UZ and or SZ. Changes in flow 
through the drifts have the potential to increase degradation of EBS components and waste 
packages, leading to a release of radionuclides. Regardless, the effects of seismic activity in the 
UZ would result in changes to the hydrologic characteristics of fractures, as expressed through 
the UZ model parameter of fracture aperture, or would be transient. 
The effects of fracture systems changes due to geologic effects on mountain-scale flow and 
radionuclide transport have been investigated using a sensitivity approach in Fault Displacement 
Effects on Transport in the Unsaturated Zone (CRWMS M&O 2000 [DIRS 151953]). The 
effects of fracture aperture changes are examined because several fracture properties 
(permeability, capillary pressure, and porosity) are functions of fracture aperture. The results 
indicate that changes in fracture aperture confined to fault zones show virtually no effect on 
transport behavior in the UZ, and increased fracture aperture applied over the entire UZ domain 
ANL-WIS-MD-000005 REV 01 
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. 
Water table elevation; Saturated flow and pathways in the SZ; 
Unsaturated flow and pathways in the UZ. 
[Note: This is a shared FEP. The scope and intent of this report is 
to quantify the amplitude of the event to be considered. The full 
technical basis for these shared FEPs is addressed collectively by 
all of the sharing FEP AMRs. Descriptor phrases not addressed or 
only partially addressed in this report are further addressed in the 
sharing FEP AMRs.] 
ExcludedLow Consequence 
This FEP specifically addresses the effects of seismic activity on 
UZ and SZ flow and transport at the mountain scale and on drift 
seepage, and addresses the possibility of a water-table rise in 
response to seismic activity (e.g., seismic pumping). However, the 
changes in flow properties is insignificant at the mountain scale, 
and the potential for a rise in water levels is insignificant with 
regard to reaching the repository level and is transient in nature. 
The FEP is therefore, Excluded. 
93 Features, Events and Processes: Disruptive Events 
results in effects that are no more significant than other uncertainties related to infiltration 
(CRWMS M&O 2000, Section 7 [DIRS 151953]). 
Muir-Wood and King (1993, pp. 22054, 22059, and 22060 [DIRS 124023]) assert that the most 
significant changes, primarily measured in terms of stream discharges, are related to normal-fault 
earthquakes. The mechanism for changing surface-water-flow directions is not readily apparent, 
unless it is related to the relocation of recharge and discharge structures, which is in turn related 
to changes in water levels. Earthquakes noticeably effect changes in groundwater levels, 
sometimes at distances far removed from the epicenter. Gauthier et al. (1996, p. 164 
[DIRS 100447]) indicate that for Yucca Mountain, the greatest strain-induced changes in 
water-table elevation occur with strike-slip faults. Such changes, if permanent, have the 
potential to alter groundwater-flow directions. The mechanisms for affecting water chemistry 
and temperature are undefined, but they are presumed linked to a change in groundwater levels 
and associated changes in geochemical conditions. However, water-level changes usually are 
transient, although the reversion to pre-earthquake levels may occur over several months. 
OBrien (1993 [DIRS 101276]) analyzed observed water level fluctuations at Yucca Mountain 
due to earthquakes in the region. Fluctuations range from 90 cm related to a 7.5 magnitude 
earthquake near Landers CA, to 20 cm for a second earthquake of 6.6 magnitude near Big Bear 
Lake, CA. The Landers and Big Bear Lake earthquakes are located 293 km and 296 km, 
respectively, from Yucca Mountain (OBrien 1993 [DIRS 101276] referenced in 
DTN: MO0310INPDEFEP.000 [DIRS 165880]). More notably, a 5.6 magnitude earthquake 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 
three days following the earthquake. Water levels in that well returned to pre-quake levels over 
a period of about 6 months. 
Alternative perspectives on seismic pumping and water-level changes are discussed in the 
Final Environmental Impact Statement (DOE 2002, p. 3-59 [DIRS 155970]), which cites to the 
work by the National Research Council (1992 [DIRS 105162] referenced in 
DTN: MO0310INPDEFEP.000 [DIRS 165880]). The panel reviewed the alternative conceptual 
model and concluded that it was infeasible. The panel went on to state that seismic pumping at 
most would have elevated the water levels a few tens of meters. 
By way of corroboration, Gauthier et al. (1996, p. 163-164 [DIRS 100447]) analyzed the 
potential effects of seismic activity on contaminant transport in the SZ due to changes in 
water-table elevation. Their simulations for TSPA-VA of the timing, amplitude, and duration of 
water-table rise indicated a maximum rise of 50 meters within an hour of a simulated seismic 
event. The simulated system returned to steady-state conditions within six months. Gauthier et 
al. (1996, pp. 163164 [DIRS 100447]) conclude 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. 
94 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Given the changes in water levels in the time following discrete seismic events as reported by the 
USGS (OBrien, 1993 [DIRS 101276] as referenced in DTN: MO0310INPDEFEP.000 
[DIRS 165880] and used as direct input) it would appear that the conclusion by Gauthier et al. 
remains valid. 
Sensitivity modeling indicates that changes to faults and fracture properties due to changes in 
stress and strain are inconsequential to groundwater flow at the mountain scale. Therefore, the 
FEP is Excluded from the TSPA-LA based on low consequence. Additionally, because 
water-table changes caused by seismic activity do not reach the repository level and are transient, 
groundwater flow and radionuclide transport are not significantly affected. The hydrologic 
response to seismic activity, therefore, does not provide a mechanism to significantly affect dose. 
TSPA Disposition: Not Applicable 
Related FEPs: 
FEPs that examine related but distinct effects and consequences: 
Tectonic activity . large scale (1.2.01.01.0A) 
Seismic-induced rockfall damages EBS components (1.2.03.02.0B) 
Seismicity associated with igneous activity (1.2.03.03.0A) 
Hydrologic response to igneous activity (1.2.10.02.0A) 
FEPs that examine similar effects and consequences: 
Water-table rise (1.3.07.02.0A) 
Earth tides (1.5.03.02.0A) 
Seismic activity changes porosity and permeability of rock (2.2.06.01.0A) 
Seismic activity changes porosity and permeability of faults (2.2.06.02.0A) 
Seismic activity changes porosity and permeability of fractures (2.2.06.02.0B) 
Seismic activity alters perched water zones (2.2.06.03.0A) 
Related Documents: 
Supplemental Discussion: None 
6.2.1.9 
Descriptor Phrases: 
Seismic Activity Changes Porosity and Permeability of Rock (2.2.06.01.0A) 
FEP Description: 
ANL-WIS-MD-000005 REV 01 
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. 
Seismic activity (rock properties in the UZ); Seismic activity (rock 
properties in the SZ) 
95 
Fault Displacement Effects on Transport in the Unsaturated Zone 
ANL-NBS-HS-000020 (CRWMS M&O 2000 [DIRS 151953] Features, Events and Processes: Disruptive Events 
[Note: This is a shared FEP. The scope and intent of this report is 
to quantify the amplitude of the event to be considered. The full 
technical basis for these shared FEPs is addressed collectively by 
all of the sharing FEP AMRs. Descriptor phrases not addressed or 
only partially addressed in this report are further addressed in the 
sharing FEP AMRs.] 
ExcludedLow Consequence Screening Decision: 
Screening Argument: Future seismic activity could redistribute strain within the system. 
Redistribution of strain could open new fractures and close some 
existing fractures, as presumed by Gauthier et al. (1996, p. 163 
[DIRS 100447]) and the strain likely is transferred, at least in part, to 
the rock matrix. Therefore, the issue is consequence rather than 
probability. 
A sensitivity analysis for UZ flow properties, discussed in the following paragraphs, was 
performed and demonstrated that the consequence in the UZ would be negligible. Additionally, 
the net effect in the SZ would be a temporary rise and/or decline in water levels (an SZ effect) and 
is addressed in FEP 1.2.10.01.0A (Hydrologic response to seismic activity). That FEP is Excluded 
based on low consequence of a temporary water level rise (or decline) on the order of a few tens of 
meters. 
Available analysis for the UZ, as discussed in the following paragraphs, considered the potential 
effects on the rock matrix and fractures. The effects of changes to matrix/fracture systems in the 
UZ on mountain-scale flow and radionuclide transport have been investigated using a sensitivity 
approach (see Fault Displacement Effects on Transport in the Unsaturated Zone, CRWMS 
M&O 2000 [DIRS 151953]). The UZ sensitivity analyses were performed with the nominal UZ 
three-dimensional flow model and used several conservative choices that, together, provide 
bounding cases for determining whether changes in fractures would significantly impact 
repository performance. The analyses were performed using a dual-permeability, active-fracture 
flow model, and were based on fracture apertures changes that could be the result of strain 
conditions or other factors. Given a change in fracture aperture, other hydrologic properties of 
fractures (permeability, capillary pressure, and porosity) were estimated using theoretical 
models. The sensitivity of a fracture aperture to mechanical strain is due to the small porosity of 
the fracture continuum. The fracture porosity is much less than the matrix (i.e., rock) porosity at 
Yucca Mountain (see CRWMS M&O 2000 Assumption 5.2 [DIRS 151953]). The matrix 
(i.e., rock), on the other hand, has much greater porosity than the fractures in general, and its 
properties are not expected to be as sensitive to mechanical strain. 
Based on the results of the UZ sensitivity analyses (CRWMS M&O 2000 [DIRS 151953]), 
changes in fracture aperture confined to fault zones showed virtually no effect on transport 
behavior in the UZ. Increased fracture aperture applied over the entire UZ domain resulted in 
effects that are no more significant than other uncertainties related to infiltration, which are 
dominated by climate change effects (CRWMS M&O 2000, Section 7 [DIRS 151953]). 
96 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Regardless of the fracture apertures used in the sensitivity study, the principle factor influencing 
flux through the UZ is infiltration at the land surface, which is linked directly to climatic 
conditions. The TSPA-LA includes a span of climatic conditions ranging from present 
conditions to wetter conditions associated with glacial periods. Consequently, the effects on 
infiltration stemming from changes in fracture aperture will be insignificant because of the 
dominance of parameters related to climate change. The evaluation of changes to fracture 
systems presented in CRWMS M&O (2000 [DIRS 151953]) relies upon information and 
assumptions related to the perched water table response and thermal hydrologic processes; these 
effects are expected to be minimal. 
The SZ model (SZ Flow and Transport Model Abstraction (BSC 2003, Section 6.5.2 
[DIRS 164870]) uses the flowing intervals concept, based on site data. indicating that only some 
of the fractures within the saturated zone contribute to the flow. Additionally, the SZ model 
implicitly includes fracture zones in the nominal case by considering the horizontal anisotropy in 
permeability located in the fractured volcanic units downgradient of the repository, with the SZ 
model producing 200 flow fields. 
The SZ model (BSC 2003, Section 6.5.2 [DIRS 164870]) likely underestimates the effect of 
matrix-diffusion processes in the SZ transport model because of possible overestimated flowinginterval 
spacing (Probability Distribution for Flowing Interval Spacing, BSC 2001, Section 1.0 
[DIRS 156965]). The overestimation occurs because the number of fractures contributing to a 
flowing interval cannot be determined from the available data. Because each flowing interval 
likely has more than one fracture contributing to it, the true flowing-interval spacing could be 
less than the spacing determined from the probability distribution. The determination of 
flowing-interval spacing potentially affects matrix-diffusion processes. 
The SZ model (BSC 2003, Section 6.5.2 [DIRS 164870]) does not explicitly address changes to 
fracture properties due to changes in stress. However, because of the existing uncertainty 
considerations for the flow field, and because of the conservative choices for flowing-interval 
spacing used for the analysis, the effect of increasing or decreasing matrix and fracture porosity 
and permeability, and/or the creation of new fractures in the SZ, would be of no significance to 
flow-and-transport characteristics. Because SZ flow characteristics are not significantly 
changed, dose is not significantly changed. 
In summary, based on the results of the UZ sensitivity analyses (CRWMS M&O 2000 
[DIRS 151953]), changes in fracture aperture confined to fault zones show virtually no effect on 
transport behavior in the UZ. Increased fracture aperture applied over the entire UZ domain 
results in effects that are no more significant than other uncertainties related to infiltration 
(CRWMS M&O 2000, Section 7 [DIRS 151953]). Because of the existing uncertainty 
considerations for the flow field and the conservative choices for flowing-interval spacing used 
for the SZ analysis (BSC 2003 [DIRS 164870]), the effect of opening or closing fractures and/or 
the creation of new fractures in the SZ would be of no significance to the flow-and-transport 
characteristics. Because flow characteristics are not significantly changed, dose is not 
significantly changed. Furthermore, the presence and durability of the drip shield will mitigate 
any increased flux during the repository performance period (10,000 years). Consequently, this 
FEP is Excluded from the TSPA-LA based on low consequence. 
97 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
TSPA Disposition: 
Related FEPs: 
FEPs that examine related but distinct effects and consequences 
Tectonic activitylarge scale (1.2.01.01.0A) 
Metamorphism (1.2.05.00.0A) 
Diagenesis (1.2.08.00.0A) 
Earth tides (1.5.03.02.0A) 
FEPs that examine similar effects and consequences 
Hydrologic response to seismic activity (1.2.10.01.0A) 
Seismic activity changes porosity and permeability of faults (2.2.06.02.0A) 
Seismic activity changes porosity and permeability of fractures (2.2.06.02.0B) 
Seismic activity alters perched water zones (2.2.06.03.0A) 
Matrix diffusion in the SZ (2.2.08.08.0A) 
Matrix diffusion in the UZ (2.2.08.08.0B) 
Related Documents: 
Supplemental Discussion: None 
6.2.1.10 Seismic Activity Changes Porosity and Permeability of Faults (2.2.06.02.0A) 
FEP Description: 
Descriptor Phrases: 
ANL-WIS-MD-000005 REV 01 
Seismic activity (fault displacement or vibratory ground motion) 
has a potential to produce jointed-rock motion and change stress 
and strains that alter the permeability along faults. This could 
result in reactivation of preexisting faults or generate new faults 
and significantly change the flow and transport paths, alter or 
short-circuit the flow paths and flow distributions close to the 
repository, and create new pathways through the repository. These 
effects may decrease the transport times for potentially released 
radionuclides. 
Seismic activity (faults in the UZ), Seismic activity (faults in the 
SZ) 
[Note: This is a shared FEP. This scope and intent of this report is 
to quantify the amplitude of the event to be considered. The full 
technical basis for these shared FEPs is addressed, collectively, by 
all of the sharing FEP AMRs. Descriptor phrases not addressed or 
98 
Not Applicable 
Fault Displacement Effects on Transport in the Unsaturated Zone 
ANL-NBS-HS-000020 (CRWMS M&O 2000 [DIRS 151953] 
SZ Flow and Transport Model Abstraction 
MDL-NBS-HS-0000210 (BSC 2003 [DIRS 164870] Features, Events and Processes: Disruptive Events 
only partially addressed in this report are further addressed in the 
sharing FEP AMRs.] 
ExcludedLow Consequence Screening Decision: 
Screening Argument: Future seismic activity could redistribute strain within the system. 
Redistribution of strain could open new fractures and close some 
existing fractures, as presumed by Gauthier et al. (1996, p. 163 
[DIRS 100447]). It is likely that at least some of this redistribution 
would occur within the faults zones. 
A sensitivity analysis for UZ fracture apertures in fault zones, discussed in the following 
paragraphs, was performed and demonstrated that the consequence of this FEP would be 
negligible. Furthermore, regardless of the strain distribution, the net effect of seismic activity in 
the SZ is the temporary rise and/or decline in water levels associated with seismic events as 
addressed in FEP 1.2.10.01.0A (Hydrologic response to seismic activity). That FEP was Excluded 
based on low consequence of a temporary water level rise (or decline) on the order of a few tens of 
meters. 
Two conclusions from Sweetkind et al. (1997, pp. 67 to 71 [DIRS 100183]) suggest that faulting 
and fracturing are spatially related. Spatial relationships based on the results of underground 
fault mapping of faults have led to the definition/description of zones of influence around faults 
based on the observation that fracture frequency generally increases as faults are approached. 
Mapping results have shown that widths of zones of influence are in general quite narrow, 
ranging from less than 1 meter to about 7 meters from the faults. The second conclusion is that 
the width of the zone of influence in the immediate vicinity of a fault generally correlates with 
the amount of cumulative fault offset. Therefore, faults having the largest potential future 
displacement are the most likely to influence the repository block. Faults having tens of meters 
of cumulative offset (e.g., faults at ESF Stations 11+20, 67+88, and 70+58) have zones of 
influence that range up to 10 meters wide. Intrablock faults having very small amounts of 
cumulative offset (1 m to 5 m) have zones of influence that are 1 to 2 meters wide. 
Consequently, the presence of gouge and brecciated zones only in limited proximity to fault 
planes suggests that much of the strain will be mechanically dissipated within or near the fault 
planes. For instance, in the Solitario Canyon fault zone in the ECRB Cross Drift, the total 
displacement is approximately 260 meters, but the gouge and brecciated zones are limited to less 
than 20 meters from the fault trace (Mongano et al. 1999, pp. 59-65 [DIRS 149850]). Similarly, 
the Dune Wash fault exposed in the ESF exhibits a cumulative offset of 65 meters, but the zone 
of increased fracture frequency in the vicinity of the fault is only 6 meters to 7 meters wide 
(Sweetkind et al. 1997, Table 21 [DIRS 100183]). A third example is the Sundance fault in the 
ECRB Cross Drift. The Sundance fault has a presumed, though indeterminate, displacement of 
several meters. However, the footwall rock is intact at a distance of only 10 cm from the fault 
plane. The hanging wall of the Sundance fault is slightly more fractured, having an intensely 
fractured zone about 1 meter thick (Mongano et al. 1999, pp. 5254 [DIRS 149850]). 
Another aspect of faulting that could be important to repository performance is the displacement 
on existing faults, particularly within the repository block, or the formation of new faults. 
99 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Section 6.2.1.2 and Table 6-4 of this report (ANL-WIS-MD-000005 REV 01) provide a 
discussion of probabilistic fault displacements. With regard to the formation of new faults, the 
PSHA (CRWMS M&O 1998, p. 8-7 [DIRS 103731] and DTN: MO0004MWDRIFM3.002 
[DIRS 149092], referring to intact rock at Points 7d and 8d) indicates that mean displacements 
in the intact rock are less than 0.1 cm for a 10-8 annual-exceedance probability (see Assumption 
5.1 of this report, ANL-WIS-MD-000005 REV. 01). The development of new faults and 
fractures is inferred from the PSHA to be of low probability and is, therefore, not further 
considered within this FEP. 
Most of the large displacements are expected to occur along existing block-bounding faults. The 
largest mean predicted displacement at 10-8 is associated with the Solitario Canyon and the mean 
displacement is estimated to be on the order of 10 meters. The median predicted displacement is 
calculated, however, to be on the order of only a few meters. (See FEP 1.2.02.03.0A (Fault 
displacement damages EBS components) for a table of estimated displacements). The effects of 
this range of displacements are addressed by the range of aperture conditions presented in Fault 
Displacement Effects on Transport in the Unsaturated Zone (CRWMS M&O 2000, Section 
6.2.2.3 [DIRS 151953]), as discussed in the following paragraphs. 
The effects of changes to fracture systems in the UZ fault zones have been investigated using a 
sensitivity approach (CRWMS M&O 2000 [DIRS 151953]). The sensitivity study was 
performed with the nominal UZ three-dimensional flow model and uses several conservative 
approaches that together provided bounding cases for determining whether changes in fractures 
will significantly impact repository performance. The analysis was performed using a 
dual-permeability, active-fracture flow model, and was based on fracture apertures changes that 
could result from changes in strain conditions or other factors. Given a change in fracture 
aperture, other fracture hydrologic properties (permeability, capillary pressure, and porosity) 
were estimated using theoretical models CRWMS M&O 2000 ([DIRS 151953]). 
The sensitivity study (CRWMS M&O 2000 [DIRS 151953]) included two bounding cases: 
(1) that changes in fracture properties occur over the entire UZ domain (fault zones and fractured 
rock), or (2) that the effects of fault displacement are limited to fracture-property changes in fault 
zones. These were modeling cases chosen to bound a presumed range of fracture-aperture 
changes resulting from fault movement. No direct observations for Yucca Mountain relate stress 
caused by fault displacement to strain and the resultant changes in fracture aperture. The 
bounding cases were used to simulate a response beyond that of the expected geologic response. 
The second bounding case (effects of fault displacement limited to fault zones) is applicable to 
this discussion and is justified based on conclusions by Sweetkind et al. (1997, pp. 67 to 71 
[DIRS 100183]) and field observations by Mongano et al. (1999 [DIRS 149850]), previously 
described. 
A potentially conservatism for the sensitivity analysis lies in the estimated fracture aperture for 
the bounding case. A maximum, ten-fold increase in fracture aperture is selected as a modelers 
upper-bounding value and was justified in CRWMS M&O 2000 ([DIRS 151953]). The 
justification cites distance-strain relationships derived from models for a 1-meter displacement 
along a strike-slip fault (used as an analogue, though not directly representative of normal-fault 
response) at Yucca Mountain and for a 1-meter displacement on a theoretically normal fault. 
The changes in fracture apertures for the sensitivity analysis were derived presuming a 10-meter 
100 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
fault movement along the Solitario Canyon and multiplying the strains cited in the justification. 
This corresponds to the projected mean value at 10-8 annual frequency (see Assumption 5.1 of 
this report, ANL-WIS-MD-000005 REV 01) and serves as the basis for FEPs screening. The 
potential for conservatism is mentioned primarily because the presumed 10-meter displacement, 
although a mean value, is conservative when compared to probabilistically-determined (median 
and 85th fractile) and observed fault displacements. The results of the PSHA (CRWMS M&O 
1998, Figure 8-3 [DIRS 103731]) indicate that, for the Solitario Canyon fault, there is a large 
uncertainty range in the potential displacements from 3 meters (the median value) to 
approximately 9 meters (the 85th fractile value) at the 10-8 annual-exceedance probability. By 
contrast, the maximum measured single-event Quaternary displacement (i.e., during the past 1.6 
million years) on the Solitario Canyon fault is only 1.3 meters (Ramelli et al. 1996, Table 4.7.3 
[DIRS 101106]). 
The results of the sensitivity study (CRWMS M&O 2000 [DIRS 151953]) has shown that 
fracture aperture changes confined to fault zones resulted in virtually no effect on transport 
behavior in the UZ (CRWMS M&O 2000, Section 7 [DIRS 151953]). Because neither the flow 
nor the transport are significantly affected by fracture aperture changes in fault zones, changes in 
the stress state of fractures in faults do not provide a mechanism to significantly affect dose. 
Because dose is not significantly affected, the effects of faults and changes on the 
flow-properties of faults are Excluded based on low consequence. However, the evaluation of 
changes to fracture systems presented in CRWMS M&O (2000 [DIRS 151953]) relied upon 
information and assumptions related to the perched water table response and thermal hydrologic 
processes, but effects are expected to be minimal and are being evaluated. 
By way of corroboration, an early analysis of the effect of a fault on flow in the SZ was 
conducted and documented in Chapter 10 of the TSPA for the Viability Assessment (CRWMS 
M&O 1998, Section 10.5.3 [DIRS 100369]). The corroborative analysis suggested that there 
would be negligible impact on performance, even though fault hydraulic conductivities were 
varied over five orders of magnitude for the modeling effort. 
Also, by way of corroboration, Gauthier et al. (1996, pp. 163164 [DIRS 100447]) analyzed the 
potential effects of seismic activity on contaminant transport in the SZ due to changes in 
water-table elevation based on TSPA-VA modeling. Their analysis indicates that the greatest 
strain-induced changes in water-table elevation occur with strike-slip faults. Simulations of the 
timing, amplitude and duration of a water-table rise indicate a maximum rise of 50 meters within 
an hour of a simulated event. The simulated system returns to steady-state conditions within six 
months. Gauthier et al. (1996, pp. 163 and 164 [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. 
Given the response of regional water levels to seismic events, as discussed in FEP 1.2.10.01.0A, 
the conclusion by Gauthier for TSPA-VA still appears valid. 
101 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
In summary, effects in the UZ would be transient or would result in changes to the hydrologic 
characteristics of fractures, as expressed through the parameter of fracture aperture. The effects 
of changes to fracture systems due to geologic effects on mountain-scale flow and radionuclide 
transport have been investigated using a sensitivity approach (CRWMS M&O 2000 
[DIRS 151953]). The results indicate that changes in fracture aperture confined to fault zones 
show virtually no effect on transport behavior in the UZ, and increased fracture aperture applied 
over the entire UZ domain results in effects that are no more significant than other uncertainties 
related to infiltration (CRWMS M&O 2000, Section 7 [DIRS 151953]). Effects in the SZ would 
be transient. Therefore, this FEP is of low consequence and is Excluded from the TSPA-LA. 
Not Applicable TSPA Disposition: 
Related FEPs: 
FEPs that examine related but distinct effects and consequences 
Tectonic activitylarge scale (1.2.01.01.0A) 
Metamorphism (1.2.05.00.0A) 
Earth tides (1.5.05.02.0A) 
Diagenesis (1.2.08.00.0A) 
FEPs that examine similar effects and consequences 
Hydrologic response to seismic activity (1.2.10.01.0A) 
Seismic activity changes porosity and permeability of rock (2.2.06.01.0A) 
Seismic activity changes porosity and permeability of fractures (2.2.06.02.0B) 
Seismic activity alters perched water zones (2.2.06.03.0A) 
Fault Displacement Effects on Transport in the Unsaturated Zone Related Documents: 
ANL-NBS-HS-000020 (CRWMS M&O 2000 [DIRS 151953]) 
Supplemental Discussion: The Screening Argument above embodies the results of analyses 
that examined the consequence to dose and the geologic realities of 
faulting. Additional data on the fault-and-fracture relationships are 
available to support the conclusions drawn above and provide 
additional support to the preceding argument. 
The conclusions drawn were based on site data that are the source for the development of a suite 
of parameters used to characterize fractures. To provide additional context for the preceding 
argument, examples of the types and sources of data available are provided in the following 
paragraphs. 
An analysis of fracture apertures is available from the ECRB Cross Drift Study (Mongano et al. 
1999, p. 79 and Figure 16 [DIRS 149850]). The largest aperture recorded was 520 mm. 
Approximately 67 percent of the observed fractures exhibited zero aperture. Of the greater 
than 1800 fractures measured, only 40 apertures, or about 2 to 3 percent, were measured as 
greater than 20 mm. The remaining apertures were 20 mm or less. 
102 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
The relationship of fractures smaller than 1 meter in length to faults was evaluated by visual 
examination of every fault in the ESF (Sweetkind et al. 1997, p. 68 [DIRS 100183]) that could be 
correlated with a fault mapped at the land surface (Day et al. 1998 [DIRS 100027]). Four 
principal conclusions listed below provide further evidence that the amplitude and distribution of 
the effects of changes in fracture aperture is likely conservative. Based on observations in the 
ESF (Sweetkind et al. 1997, pp. 6771 [DIRS 100183]), the four principal conclusions regarding 
fault-to-fracture relationships are: 
1) The width of the zone of influence on fracture frequency in the immediate vicinity of a 
fault is, in general, quite narrow, ranging from less than 1 meter to about 7 meters 
from a fault. 
2) The width of the zone of influence in the immediate vicinity of a fault generally 
correlates with the amount of cumulative fault offset. Therefore, faults with the largest 
potential future displacement are the most likely to influence the repository block. 
Faults with tens of meters of cumulative offset (e.g., faults at ESF Stations 11+20, 
67+88, and 70+58) have zones of influence up to 10 meters wide. The limited 
available data from block-bounding faults are not definitive regarding the nature of 
attendant fracturing. Intrablock faults with very small amounts of cumulative offset 
(1 to 5 m) have zones of influence that are 1 to 2 meters wide. 
3) The width of the zone of influence around a fault does not appear to be related to 
depth, at least within the ESF. The width of the zones of influence is similar for small 
faults observed along the North Ramp, where overburden is 50 to 60 meters thick, as it 
is for small faults observed elsewhere in the ESF, where overburden thickness is two 
to three times greater than at the North Ramp. However, upward-splaying faults can 
result in apparent broad zones of influence at land surface because of the overlap of 
fractured zones surrounding individual fault splays. 
4) The amount of deformation associated with faults appears, in part, to be dependent 
upon which lithologic units are faulted. In the ESF, overall variability in the 
frequency of fractures 1-meter long or longer is primarily a function of lithology, not 
proximity to faults (Sweetkind et al. 1997, p. 66 [DIRS 100183]). Each 
lithostratigraphic unit at Yucca Mountain has characteristic fracture attributes, 
including predominant orientations, spacing, trace length, and joint type that are 
lithologically controlled (Sweetkind et al. 1997, p. 74 [DIRS 100183]); and it is 
inferred that each is unique in its ability to deform by distributed slip. The result is 
stratigraphic control of structural geometrywhat may be a discrete break in one 
lithostratigraphic unit, may be a broad zone of distributed deformation in another. 
Consequently, the modeling case of mountain-scale distribution of changes in 
fracture aperture changes is considered conservative. 
6.2.1.11 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 
103 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Descriptor Phrases: 
Screening Decision: 
Screening Argument: 
Strain is more likely to affect existing features rather than to create new fractures as evidenced 
by field observation of reactivation features and the geologic history of Yucca Mountain. 
Although it does not directly address the reactivation of fractures or the creation of fractures, the 
PSHA (CRWMS M&O 1998 [DIRS 103731]) examines the probability of movement along 
existing fractures with no measurable cumulative displacement and the development of 
small-scale displacements in the intact rock. The results are used to infer that the reactivation of 
fractures and the development of new fractures are of low probability and are, therefore, not 
further considered within this FEP. This inference concerning small-displacement probabilities 
to fracture probabilities is possible because of the definition of fractures. 
According to the NRC (1999, p. 55 [DIRS 135621]), fractures are characterized by motion 
perpendicular to the fracture walls (extension fractures), by motion parallel to the fracture walls 
(shear fractures), or by very small displacement normal to their surfaces, and little or no 
displacement parallel to their surfaces (joints). The range of displacements extends upward to 
amplitudes that characterize faults, which typically originate as shear fractures capable of 
fracturing across discontinuities. According to Bates and Jackson (1987, p. 257 [DIRS 164050]), 
fracture is a general term for any break in a rock, whether or not it causes displacement, due to 
mechanical failure by stress. Fracture includes cracks, joints, and faults. Consequently, 
fractures involve a range from no displacement, up to and including, small-scale movement. 
ANL-WIS-MD-000005 REV 01 
preexisting fractures or generation of new fractures. Generation of 
new fractures and reactivation of preexisting fractures may 
significantly change the flow and transport paths, alter or 
short-circuit the flow paths and flow distributions close to the 
repository and create new pathways through the repository. These 
effects may decrease the transport times for potentially released 
radionuclides. 
Seismic activity (fractures in the UZ), Seismic activity (fractures in 
the SZ) 
[Note: This is a shared FEP. This scope and intent of this report is 
to quantify the amplitude of the event to be considered. The full 
technical basis for these shared FEPs is addressed collectively by 
all of the sharing FEP AMRs. Descriptor phrases not addressed or 
only partially addressed in this report are further addressed in the 
sharing FEP AMRs.] 
ExcludedLow Consequence 
The tectonic strain rate controlling the seismic and 
fault-displacement events leading to the small-scale displacements 
was evaluated as an uncertain parameter in the PSHA, and the 
uncertainty in the tectonic rate is, thereby, reflected in the PSHA 
results (see the FEP 1.2.01.01.0A Tectonic activitylarge scale). 
A sensitivity analysis, discussed below, was performed and 
demonstrated that the consequence would be negligible. 
104 Features, Events and Processes: Disruptive Events 
Tectonically induced strain can be accommodated in several ways, including the formation of 
new fractures and/or movement on existing fractures. 
The PSHA (CRWMS M&O 1998, p. 8-7 referring to intact rock, or condition d at hypothetical 
Points 7 and 8 within the repository block [DIRS 103731]) indicates that the probability of a 
movement (i.e., minimal displacement) developing in the intact rock has less than a 10-8 
annual-exceedance probability (see Assumption 5.1 of this analysis report, ANL-WIS-MD- 
000005 REV. 01). By inference, this corresponds to the development of new fractures. The 
PSHA (CRWMS M&O 1998, Figures 8.10 and 8.13 for points 7c and 8c [DIRS 103731]) 
indicates that fractures within the current repository area having no measured displacements can 
be expected to experience on the order of 0.1 to 1 cm of displacement at a 10-8 annualexceedance 
probability. By inference, this corresponds to the annualized probability for 
reactivation of fractures. These small-scale displacements along existing fractures and in the 
intact rock examined in the PSHA, at some undefined scale of movement, begin to fall within the 
range of the definition of fractures, as previously described. By inference from the PSHA, the 
development of new fractures due to seismic activity and associated fault displacement is 
inferred to be of low probability. It can also be inferred that movement along existing fractures 
is more likely than the development of new fractures, an inference that is directly supported by 
field observations and consideration of the geologic history of Yucca Mountain. 
Field observations indicate that the rock at Yucca Mountain is highly fractured and that existing 
fractures and joints have been subject to reactivation. Evidence for reactivation of joints includes 
the presence of thin breccia zones along cooling joints and observable slip lineations along joint 
surfaces (Sweetkind et al. 1996 [DIRS 106957]). Cooling joints formed originally as tensional 
openings, have only face separation, not shear. However, thin selvages of tectonic breccia 
commonly are present along the trace of cooling joints, indicating later slip. Based on these field 
observations, the fracture network appears to act as a significant pre-existing weakness in the 
rock mass that can accommodate extensional strain through distributed slip along many 
reactivated joints. Coupled with the results of the PSHA for movement in the intact rock, it 
would appear that changes in strain are more likely to be accommodated along existing fractures 
rather than to initiate new fractures. 
Fractures also, theoretically, could be created by mechanisms not directly related to seismicity or 
fault displacements, as examined in the PSHA, including changes in the stress field related solely 
to tectonism, without attendant seismicity or fault displacement. However, based on the geologic 
history of Yucca Mountain, tectonic changes, and hence changes in the stress field leading to 
fracture development, would occur at low rates (CRWMS M&O 2000, Section 6.3.1 
[DIRS 142321]). Savage et al. (1999 [DIRS 118952]) present an evaluation of the 
strain-accumulation rate at Yucca Mountain, Nevada, for the period from 1983 to 1998, and 
address alternative interpretations by Wernicke et al. (1998 [DIRS 103485]) that suggest greater 
strain-accumulation rates. Regardless of the existing strain-accumulation rate, the existing 
fracture characteristics at Yucca Mountain have developed over an extended period and over a 
varying range of stress-and-strain conditions. For example, the development of Yucca Mountain 
itself (including deposition of the tuff layers, block faulting, and subsequent development of 
cooling joints and fractures) occurred over a period of 2.5 to 3 million years (inferred from 
Fridrich 1999, pp. 184189 [DIRS 118942]; and Sawyer et al. 1994, pp. 1305 and 1312 
[DIRS 100075]). The rate of regional tectonism has decreased greatly since late Miocene 
105 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
(inferred from Fridrich et al. 1998, pp. 1 and 2 [DIRS 164051]). The stress conditions associated 
with these earlier processes vary considerably from existing conditions. Consequently, unless 
stress vectors acting on Yucca Mountain were to deviate markedly and rapidly from those acting 
(either locally or regionally) within the past few million years, the shear strength of intact rock 
will not be exceeded (i.e., new fracturing will not be initiated) due to the presence of existing 
fracture sets favorably oriented to accommodate increased stresses and strains. 
The effects of changes to fracture systems in the UZ fault zones have been investigated using a 
sensitivity approach (Fault Displacement Effects on Transport in the Unsaturated Zone CRWMS 
M&O 2000 [DIRS 151953]). The sensitivity study was performed with the nominal UZ 
three-dimensional flow model using several conservative approaches that, together, provide 
bounding cases for determining whether changes in fractures would significantly impact 
repository performance. The analysis was performed using a dual-permeability, active-fracture 
flow model, and was based on the fracture apertures changes resulting from changes in strain 
conditions or other factors. Given a change in fracture aperture, other fracture hydrologic 
properties (permeability, capillary pressure, and porosity) were estimated using theoretical 
models. 
The sensitivity study (CRWMS M&O 2000 [DIRS 151953]) included two bounding cases: 
1) that changes in fracture properties occur over the entire UZ domain (fault zones and fractured 
rock), or 2) that the effects of fault displacement are limited to fracture-property changes in fault 
zones. These were modeling cases chosen to bound a presumed range of fracture-aperture 
changes resulting from fault movement. There are no direct observations for Yucca Mountain 
that relate stress caused by fault displacement to strain and resultant changes in fracture aperture. 
The bounding cases were used to simulate a response beyond that of the expected geologic 
response. 
A maximum, ten-fold increase in fracture aperture was selected as a modelers upper-bounding 
value and was justified in CRWMS M&O (2000 [DIRS 151953]). The justification cites 
distance-strain relationships derived from models for a 1-meter displacement along a strike-slip 
fault (used as an analogue, though not directly representative of normal-fault response) at Yucca 
Mountain and for a 1-meter displacement on a theoretical normal fault. The changes in fracture 
apertures for the sensitivity analysis were derived presuming a 10-meter fault movement along 
the Solitario Canyon and multiplying the strains cited in the justification. The potential for being 
conservative is mentioned primarily because the presumed 10-meter displacement, although a 
mean value, is conservative when compared to probabilistically-determined (median and 85th 
fractile) and observed fault displacements. The results of the PSHA (CRWMS M&O 1998, 
Figure 8-3 [DIRS 103731] and DTN: MO0004MWDRIFM3.002 [DIRS 149092]) indicate that 
for the Solitario Canyon fault, there is a large uncertainty range in the potential displacements 
from 3 meters (the median value) to approximately 9 meters (the 85th fractile value) at the 10-8 
annual-exceedance probability (See Assumption 5.1 of this report, ANL-WIS-MD-000005 REV 
01). By contrast, the maximum measured single-event Quaternary displacement (i.e., during the 
past 1.6 million years) on the Solitario Canyon fault is only 1.3 meters (Ramelli et al. 1996, 
Table 4.7.3 [DIRS 101106]). 
The results of the sensitivity study (CRWMS M&O 2000 [DIRS 151953]) has shown that 
changes in fracture aperture confined to fault zones resulted in virtually no effect on transport 
106 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
behavior in the UZ, and that increased fracture aperture applied over the entire UZ domain 
results in effects that are no more significant than other uncertainties related to infiltration 
(CRWMS M&O 2000, Section 7 [DIRS 151953]). 
Because neither flow nor transport is significantly affected by changes in fracture aperture, dose 
is not significantly affected. The effects of faults and changes on the flow-properties of faults are 
Excluded based on low consequence. However, the evaluation of changes to fracture systems 
presented in CRWMS M&O (2000 [DIRS 151953]) relies upon information and assumptions 
related to the response of the perched water table response and thermal hydrologic processes, but 
the effects are expected to be minimal. 
In summary, effects in the UZ either would be transient or would result in changes to the 
hydrologic characteristics of fractures, as expressed through the parameter of fracture aperture. 
The effects of changes to fracture systems due to geologic effects on mountain-scale flow and 
radionuclide transport have been investigated using a sensitivity approach (CRWMS M&O 2000 
[DIRS 151953]) and indicate that changes in fracture aperture confined to fault zones show 
virtually no effect on transport behavior in the UZ, and increased fracture aperture applied over 
the entire UZ domain results in effects that are no more significant than other uncertainties 
related to infiltration (CRWMS M&O 2000, Section 7 [DIRS 151953]). Therefore, this FEP is 
of low consequence and is Excluded from the TSPA-LA. 
Not Applicable TSPA Disposition: 
Related FEPs: 
FEPs that examine related but distinct effects and consequences 
Tectonic activitylarge scale (1.2.01.01.0A) 
Metamorphism (1.2.05.00.0A) 
Diagenesis (1.2.08.00.0A) 
Earth tides (1.5.05.02.0A) 
FEPs that examine similar effects and consequences 
Hydrologic response to seismic activity (1.2.10.01.0A) 
Seismic activity changes porosity and permeability of rock (2.2.06.01.0A) 
Seismic activity changes porosity and permeability of faults (2.2.06.02.0A) 
Seismic activity alters perched water zones (2.2.06.03.0A) 
Fracture flow in the UZ (2.2.07.08.0A) 
Water- conducting features in the SZ (2.2.07.13.0A) 
Fault Displacement Effects on Transport in the Unsaturated Zone Related Documents: 
ANL-NBS-HS-000020 (CRWMS M&O 2000 [DIRS 151953]) 
Characterize Framework for Seismicity and Structural 
Deformation at Yucca Mountain, Nevada 
ANL-CRW-GS-000003 (CRWMS M&O 2000 [DIRS 142321]) 
107 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Supplemental Discussion: None 
6.2.1.12 Seismic Activity Alters Perched Water Zones (2.2.06.03.0A) 
FEP Description: 
Descriptor Phrases: 
Screening Decision: 
Screening Argument: 
Changes in stress due to all causes have the potential to result in strains that affect 
groundwater flow-and-transport properties, leading to increased or decreased dose. It seems 
that a change in stress could, in itself, adequately seal a zone such that perched water develops. 
However, the generation of a perched water zone above the repository due to seismic activity, 
could potentially affect the flow of water to waste emplacement drifts. This potential effect is 
indirectly addressed by using focused flow in the seepage model abstraction. 
Below the repository, the potential to release perched water because of stress changes and 
fracture openings due to seismic activity is considered. Hypothetically, such changes have the 
potential to result in a relatively sharp pulse of radionuclides, if the perched water contains 
radionuclides, and if the perched water is allowed to drain. 
This FEP was previously addressed for TSPA-SR based on perched zone water volume 
calculations provided in Attachment X of BSC 2001 [DIRS 154826]. The TSPA-SR analysis 
indicated that the existing volume of perched zone water is insignificant because it represents 
only a few years of flux through the system. However, because of the repository footprint 
change for TSPA-LA, the calculation was updated in Attachment I of BSC 2003 [DIRS 164873], 
which serves as the technical basis for the FEP exclusion. Although the calculated values vary 
from those for TSPA-SR due to the change in the repository footprint, the approach used to 
exclude the FEP, and the finding of insignificance have not changed between TSAP-SR and 
TSPA-LA. This is because much of the TSPA-LA footprint overlaps with the TSPA-SR 
footprint, and the total area of the repository is roughly equivalent. 
As shown by both the TSPA-SR and the TSPA-LA calculations, the relatively small amount of 
water in the fracture domain below the repository, and the radionuclides that could be contained 
ANL-WIS-MD-000005 REV 01 
Strain caused by stress changes from tectonic or seismic events 
alters the rock permeabilities that allow formation and persistence 
of perched water zones. 
Seismic activity (alters perched water) 
[Note: This is a shared FEP. The scope and intent of this report is 
to quantify the amplitude of the event to be considered. The full 
technical basis for these shared FEPs is addressed collectively by 
all of the sharing FEP AMRs. Descriptor phrases not addressed or 
only partially addressed in this report are further addressed in the 
sharing FEP AMRs.] 
ExcludedLow Consequence 
This a shared FEP and the technical basis is fully addressed in the 
related FEP AMR cited therein. Only a partial conceptual 
volumetric argument is presented, as follows. 
108 Features, Events and Processes: Disruptive Events 
in this water, are not expected to cause a significant pulse in radionuclide mass flux at the 
water table. For TSPA-LA, the unsaturated zone flow model shows that the volume of perched 
water in the high-permeability fracture domain below the repository ranges from about 466 m3 to 
1,190 m3. This volume may be compared with the water flux entering the repository footprint 
(i.e., that average infiltration rate times the area of the repository footprint). The infiltration 
volume ranges from 2000 to 192,000 m3/yr. As shown in Attachment I, the perched water 
volume is seen to represent about 0.006 to 0.2 years of water flux. Thus, the perched water 
volume in high-permeability fractures is small compared to the water flux through the repository 
horizon for one year, and the FEP is Excluded based on low consequence. Even if released 
instantaneously by a seismic event, the release of perched water would have no significant 
consequence on exposure or release of radionuclides to the accessible environment. Therefore, 
this FEP is Excluded from the TSPA-LA based on low consequence. 
TSPA Disposition: Not Applicable 
Related FEPs: 
FEPs that examine related but distinct effects and consequences 
Tectonic activitylarge scale (1.2.01.01.0A) 
FEPs that examine similar effects and consequences 
Hydrologic response to seismic activity (1.2.10.01.0A) 
Seismic activity changes porosity and permeability of rock (2.2.06.01.0A) 
Seismic activity changes porosity and permeability of faults (2.2.06.02.0A) 
Seismic activity changes porosity and permeability of factures (2.2.06.02.0B) 
Perched water develops (2.2.07.07.0A) 
None Related Documents: 
Supplemental Discussion: None 
6.2.2 Igneous-Related FEPs 
The following subsections provide the screening decision and technical basis for inclusion and 
exclusion of the following igneous-related FEPs. 
Igneous activity changes rock properties (Section 6.2.2.1) 
Igneous intrusion into repository (Section 6.2.2.2) 
Igneous intrusion interacts with EBS components (Section 6.2.2.3) 
Magma or pyroclastic base surge transports waste (Section 6.2.2.4) 
Eruptive conduit to surface intersects repository (Section 6.2.2.5) 
Ashfall (Section 6.2.2.6) 
Ash redistribution via soil and sediment transport (Section 6.2.2.7) 
Hydrologic response to igneous activity (Section 6.2.2.8) 
1.2.04.02.0A 
1.2.04.03.0A 
1.2.04.04.0A 
1.2.04.05.0A 
1.2.04.06.0A 
1.2.04.07.0A 
1.2.04.07.0C 
1.2.10.02.0A 
ANL-WIS-MD-000005 REV 01 109 Features, Events and Processes: Disruptive Events 
6.2.2.1 
FEP Description: 
Igneous Activity Changes Rock Properties (1.2.04.02.0A) 
Descriptor Phrases: 
Screening Decision: 
Screening Argument: 
An appropriate analog for understanding the components of a volcanic event is the Paiute Ridge 
intrusive/extrusive center (Byers and Barnes 1967 [DIRS 101859]) on the northeastern margin of 
the Nevada Test Site. Paiute Ridge is a small-volume Miocene volcanic center comparable in 
volume and composition to Quaternary volcanoes near Yucca Mountain (CRWMS M&O 1998 
p. 5-29 [DIRS 105347]). Paleomagnetic, geochronologic, and geochemical data indicate that the 
entire intrusive/extrusive complex formed during a brief magmatic pulse and, thus, represents a 
single volcanic event (Ratcliff et al. 1994 [DIRS 106634]; and CRWMS M&O 1998, p. 5-29 
[DIRS 105347]). The vents and associated dike system formed within a 
north-northwest-trending extensional graben provide excellent exposures of a variety of system 
depths including remnants of surface lava flows, volcanic conduits, and dikes and sills intruded 
into tuff country rock at depths of up to 300 meters (CRWMS M&O 1998, pp. 5-27 through 5-41 
[DIRS 105347]). There is evidence of shallow structural control of dike emplacement at Paiute 
Ridge, including dike emplacement along fault planes (Byers and Barnes 1967 [DIRS 101859]; 
and CRWMS M&O 1998, pp. 5-27 and 5-28, [DIRS 105347]). Dike lengths at Paiute Ridge 
range from <1 km to 5 km (CRWMS M&O 1998, p. 5-31 [DIRS 105347]), comparable to the 
range estimated for post-Miocene volcanism near Yucca Mountain. 
ANL-WIS-MD-000005 REV 01 
Igneous activity near the underground facility causes extreme 
changes in rock stress and the thermal regime, and may lead to 
rock deformation including activation, creation, and sealing of 
faults and fractures. This may cause changes in the rock 
hydrologic and mineralogic properties. Permeabilities of dikes and 
sills and the heated regions immediately around them can differ 
from those of country rock. Mineral alterations can also change 
the chemical response of the host rock to contaminants. 
Igneous activity (rock properties in the UZ), Igneous activity (rock 
properties in the SZ) 
[Note: This is a shared FEP. This scope and intent of this report is 
to quantify the amplitude of the event to be considered. The full 
technical basis for these shared FEPs is addressed collectively by 
all of the sharing FEP AMRs. Descriptor phrases not addressed or 
only partially addressed in this report are further addressed in the 
sharing FEP AMRs.] 
ExcludedLow Consequence 
With regard to extreme changes in hydrologic properties, sills and 
dikes initially intrude into the country rock as molten material and 
then cool. Cooling joints are formed and resulting permeabilities 
may be greater than, equivalent to, or less than the surrounding 
country rock. However, the scale of these effects is limited to a 
few meters around the dike and changes in properties are, 
therefore, of low consequence. 
110 Features, Events and Processes: Disruptive Events 
Carter-Krogh and Valentine (1996, pp. 7 and 8 [DIRS 160928] referenced in 
DTN: MO0310INPDEFEP.000 [DIRS 165880]) described the margins of the Paiute Ridge dike 
complex and the interaction of dikes and faults. The description is as follows: 
PR dike contains ubiquitous near-vertical joints that result in a pervasive platy 
texture with plates parallel to the dike-host contact. Conversely, with the 
exception of local cooling joints in fused wall rock (extending 10-20 cm into the 
wall rock, perpendicular to the dike margin), joints are never visible in the host 
rock along the length of the dike. The contact between basalt and the tuff host 
rock is consistently smooth and shows no brecciation. Along strike at this 
contact, the tuff host rock is fused or welded to varying degrees: in places the tuff 
is completely welded and forms black vitrophyre that grades rapidly away from 
the contact, over a distance of ca 20100 cm, into nonwelded tuff that is 
apparently unaffected by the dike. In other places the tuff is only partly welded at 
the contact and black fiamme are elongated parallel to the contact. We infer that 
this contact welding is the combined result of heat from the dike and 
compressive stress exerted by the flowing magma on the wall rocks. Welded host 
rock commonly contains vesicles that are elongated vertically and parallel to the 
margin. In some places, welded tuff coats the basalt and displays rills or elongate 
smooth ridges (flutes). Most rills plunge nearly vertically, however, a subhorizontal 
rill is present in the central part of the dike. At the dike tip, exposed at 
Slanted Buttes, scoria patches crop out near the dike-host contact. 
The two eastern dikes, M and E  show geometries and textures similar to those 
of PR; however, M dike is much shorter and does not feed a sill, and E dike was 
emplaced closest to the paleosurface and feeds two sills. M dike  visibly 
occupies a normal fault, oriented N40 W, 61 E,  Its host rocks are only 
Tertiary tuffs, which show no brecciation or jointing near the dike contact  
Texture within the dike is characterized by a vertical platy fabric that parallels the 
dike margins. E dike is the eastern-most dike studied within the graben.  Near 
the neck, the dike visibly occupies a NNW-trending, steeply E-dipping normal 
fault that displaces bedded tuffs 3.5 m and does not cut the dike The texture of 
E dike is characterized by the pervasive vertical platy fabric common to M and 
PR dikes. Adjacent host tuffs are not jointed nor brecciated, except for local 
vertical jointing of the Rainier Mesa tuff, which is intruded by the dike at its 
shallowest level. The contact of the dike and host tuff is preserved in places and 
varies from partly to completely welded in the same manner as described above 
for the PR dike. Where complete welding has occurred, vesicles are vertical and 
parallel the dike margin. Contact welding of the host tuffs formed oblate fiamme 
that parallel the dike-host contact. Visible thermal effects on the wall rocks 
disappear within one meter of the dike margin. 
This suggests that zones of change in rock properties (i.e., formation of vitrophyres and/or 
various degrees of welding of the host rock) are limited to between a few tens of centimeters to, 
at most, a meter perpendicular to the dike. Other features such as the platy texture along the dike 
111 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
margins and vesicles in the welded tuff are oriented parallel to the dike margins. This suggests 
that the primary direction of increased or decreased permeability (if any) is parallel with the dike 
margins. The description also indicates the interaction of faults and dikes and alludes to the 
segmented, discontinuous, en echelon structures observed for the dike complex. 
Most researchers conclude that once dikes feeding volcanoes enter the shallow upper crust, their 
location and orientation is influenced by the orientation of the local stress field and the presence 
of faults that may locally control vent location and alignment. The evidence cited for these two 
conclusions includes several northeast-oriented vent alignments in the YMR and the association 
of eruptive centers with known or inferred faults (Smith et al. 1990, p. 83 [DIRS 101019]; 
CRWMS M&O 1996, Appendix E, p. AM-4 [DIRS 100116]; Connor et al. 1996, p.78 
[DIRS 135969]; Reamer 1999, Section 4.1.3.3.3 [DIRS 119693]). 
The results of the PVHA are summarized in the analysis report Characterize Framework for Igneous 
Activity at Yucca Mountain, Nevada (BSC 2003 [DIRS 163769]), and the analysis report presents 
probability distributions for the length and orientation of volcanic dikes within the repository 
footprint. The individual PVHA expert dike length distributions can be aggregated to derive a 
PHVA aggregate dike length distribution. The aggregate dike-length distribution derived from 
the PVHA has 5th-percentile, mean, and 95th-percentile values of 0.6, 4.0, and 10.1 km, 
respectively, and the most commonly assigned dike orientation centers on N30oE (BSC 2003, 
Section 6.3.2 [DIRS 163769]). The analysis, based on the results of the PVHA, also assigns the 
highest probabilities of dike orientation to azimuths of between 20 and 40 degrees (BSC 2003, 
Table 18 [DIRS 163769]). 
The anisotropic transmissivity in the SZ observed in the Yucca Mountain region has a maximum 
principal transmissivity direction of approximately N15E (BSC 2003, Section 6.5.2.10 
[DIRS 164870]), which is consistent with the fault and fracture orientation and a corroborative 
analysis by Ferrill et al. (1999, p. 1 [DIRS 118941], which indicates N30E. Based on the PVHA 
results, future dikes most likely will trend in a north-to-northeast orientation, although this may 
be altered by the presence of existing faults, or localized changes in the stress field with the 
orientation being perpendicular to the least compressive stress. A north-to-northeast orientation 
parallels or sub-parallels the faults, and fractures active in the present-day in situ stress field. 
Dike features, such as the platy texture and welded surfaces that could affect the permeability, 
will presumably parallel the dike orientation and be aligned in a north-to-northeast orientation. 
This parallel to subparallel orientation of dikes and maximum principal transmissivity, coupled 
with the expected limited affected volume of material around the dikes, indicates that dikes, even 
if differing in permeability, will not significantly affect groundwater flow patterns at the 
mountain scale. By way of corroboration, an early analysis of the effect of a dike on flow in the 
SZ was conducted and documented in Chapter 10 of the TSPA for the Viability Assessment 
(CRWMS M&O 1998, Section 10.4.4 [DIRS 100369]). The corroborative analysis suggested 
that there would be negligible impact for a dike oriented north to northeast. The analysis 
included a variety of dike lengths and locations respective to the repository area. Additionally, 
the occurrence of such a change is conditional on a low probability event of an igneous intrusion. 
CRWMS M&O (1998, p. 5-56 [DIRS 105347]) mentions the possibility of perched water 
forming near low-permeability intrusive bodies, and there is concern regarding the potential for a 
112 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
dike to provide a barrier to flow and/or cause impoundments. Because of the parallel to 
subparallel orientation of dikes with the existing orientation of the anisotropic maximum 
horizontal permeability in the SZ, a dike would not form a barrier or impoundment that would 
have any significant effect on flow in the SZ. In the UZ, the primary direction of groundwater 
flow is vertically through the fractures, although some horizontal flow component exists in the 
matrix. Because the joints on a dike margin would be near-vertical, it would seem that the 
formation of a significant perched water zone is problematic without the formation of a sill. The 
potential for sill formation is addressed in the FEP 1.2.04.03.0A (Igneous intrusion into 
repository). The formation of a perched water zone is addressed in the FEP 2.2.07.07.0A 
(Perched water develops) and has been Included in the TSPA-LA. Even if a perched water zone 
were to form and then drain, there would be only a minimal impact, as explained in 
FEP 2.2.06.03.0A (Seismic activity alters perched water zone). 
Change in fault and fracture properties (i.e., activation, creation, and sealing of faults and 
fractures) is judged to be of negligible impact on three bases. First, the orientation of the faults 
and fractures is generally parallel-to-subparallel to the maximum principal transmissivity in the 
SZ, so alteration of the faults or fractures would presumably have minimal effect. Additionally, 
the effect of changes in aperture (i.e., the mathematical equivalent of sealing or reactivation) was 
examined in Fault Displacement Effects on Transport in the Unsaturated Zone (CRWMS M&O 
2000, Section 7 [DIRS 151953]) and found to have negligible impact, and changes in fault 
properties were excluded from further consideration in TSPA-LA on that basis. Lastly, the 
potential for volcanic-generated seismic events was considered within the context of the PSHA 
and included implicitly in the probabilistic assessment of seismic ground motion hazards (see 
FEP 1.2.03.03.0A (Seismicity associated with igneous activity)). The seismic source 
characterization was also used as the basis for the earthquake approach for determining 
probabilistic fault displacements. Thus, displacements from igneous events have been implicitly 
included in evaluation of probabilistic fault displacement (i.e., reactivation and creation of new 
faults) and further consideration is unwarranted. 
With regard to extreme changes in mineralogy, it is possible that the thermal and geochemical 
influence of igneous activity could affect the rock mineralogy surrounding the igneous intrusion. 
However, igneous intrusions at natural-analogue sites are generally confined to relatively thin 
zones of rock ranging from a few to a few hundred meters (CRWMS M&O 1998, pp. 5-42 and 5-57 
[DIRS 105347] referenced in DTN: MO0310INPDEFEP.000 [DIRS 165880]). In particular, 
natural-analogue studies at the Nevada Test Site show that alteration is limited to a zone less than 
10 meters away from the intrusion/host rock contact (CRWMS M&O 1998, pp. 5-41, 5-71, and 5- 
72 [DIRS 105347] referenced in DTN: MO0310INPDEFEP.000 [DIRS 165880]). CRWMS 
M&O (1998, p. 5-42 [DIRS 105347] referenced in DTN: MO0310INPDEFEP.000 
[DIRS 165880]) further states that, Based on natural-analogue sites, there is no indication for 
extensive hydrothermal circulation and alteration, brecciation and deformation related to 
magmatic intrusion, and vapor phase recrystallization during the magmatic intrusion into the 
vitric and zeolitized tuffs. Because the alteration zone around dikes is limited to the immediate 
proximity of the dike, then, at the scale of the repository, changes in mineralogy are of low 
consequence. 
In summary, each concern posed in the FEP description has been evaluated based on site data or 
natural analogues. The subparallel orientation of dikes to transmissivity, coupled with the 
113 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
expected limited affected volume, indicates that dikes, even if differing in permeability, will not 
significantly affect groundwater flow patterns. Because the joints on the dike margin are near 
vertical, it would seem that the formation of a significant perched water zone is problematic. 
Furthermore, natural-analogue studies show that alteration is limited to a zone less than 10 
meters away from the contact at the Nevada Test Site natural-analogue sites. Consequently, 
changes in rock properties due to igneous activity do not provide a mechanism to significantly 
affect exposure or release of radionuclides to the accessible environment. Therefore, the FEP is 
Excluded from the TSPA-LA based on low consequence. 
TSPA Disposition: Not Applicable 
Related FEPs: 
FEPs that examine related but distinct effects and consequences 
Igneous intrusion into repository (1.2.04.03.0A) 
Diagenesis (1.2.08.00.0A) 
Diapirism (1.2.09.01.0A) 
Rind (chemically altered zone) forms in the near field (2.1.09.12.0A) 
Rock properties of host rock and other units (2.2.03.02.0A) 
Perched water develops (2.2.07.07.0A) 
Fracture flow in the UZ (2.2.07.08.0A) 
Groundwater conducting features in the SZ (2.2.07.13.0A) 
Geochemical interactions and evolution in the SZ (2.2.08.03.0A) 
Geochemical interactions and evolution in the UZ (2.2.08.03.0B) 
FEPs that examine similar effects and consequences 
Metamorphism (1.2.05.00.0A) 
Hydrothermal activity (1.2.06.00.0A) 
Thermally-induced stress changes in the near field (2.2.01.02.0A) 
Thermomechanical stresses alter characteristics of fractures near repository 
(2.2.10.04.0A) 
Thermomechanical stresses alter characteristics of faults near repository 
(2.2.10.04.0B) 
Thermomechanical stresses alter characteristics of rocks above and below the 
Repository (2.2.10.05.0A) 
Related Documents: None 
Supplemental Discussion: None 
6.2.2.2 Igneous Intrusion Into Repository (1.2.04.03.0A) 
FEP Description: Magma from an igneous intrusion flows into the drifts and extends 
over a large portion of the repository site, forming a sill, dike, or 
dike swarm depending on the stress conditions. This could involve 
multiple drifts. The sill could be limited to the drifts or a 
114 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
continuous sill could form along the plane of the repository, 
bridging between adjacent drifts. 
Descriptor Phrases: Dike or sill intersects one or more drifts, Magma or pyroclastic 
material intersects waste packages, In-drift flow and pathways 
through intrusive dike or sill 
Screening Decision: Included (BSC 2003, Table 9 [DIRS 163769]; BSC 2003, Table 5 
[DIRS 161838]; BSC 2003, Table 4 [DIRS 165923]) 
Screening Argument: Not Applicable 
TSPA Disposition: The primary focus of this FEP is magmatic intrusion directly into 
the repository. The following FEP discussion addresses the 
potential for such an intrusion and the resulting in drift conditions 
and waste package damage, which are Included within the 
TSPA-LA. Related FEPs discuss changes in hydrology and rock 
properties. 
Based on the results of Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
(BSC 2003, Table 22 [DIRS 163769]), the computed mean annual frequency of intersection of 
the repository footprint by a dike is 1.7  10-8 for the LA footprint compared to 1.510-8 obtained 
in the PVHA (CRWMS M&O 1996, p. 4-10 [DIRS 100116]) (see Assumption 5.1 of this 
analysis report, ANL-WIS-MD-000005 REV. 01). This is based on the repository footprint 
presented in 800-IED-EBS0-00402-000-00B and 800-IED-EBSO-00401-000-00C (BSC 2003 
[DIRS 161727] and [DIRS 162289]). The computed 5th and 95th percentiles of the uncertainty 
distribution for frequency of intersection are 7.4  10-10 and 5.5  10-8, respectively, as compared 
to 5.4  10-10 and 4.9  10-8 obtained in the PVHA (CRWMS M&O 1996, p. 4-10 
[DIRS 100116]). The mean probability is used in the TSPA-LA to weight conditional dose 
calculations. 
Igneous intrusion into the repository (i.e., igneous activity) as provided in the FEP description 
has the potential to effect both the hydrologic and geochemical characteristics of the site, and due to 
extreme changes the in-drift environment, could damage EBS components and the waste packages. 
Combined, this could result in the release of radionuclides and affect the radiological exposure of 
the RMEI. 
Because the probability of igneous intrusion is slightly greater than the FEP screening 
probability threshold, and because waste package damage cannot be constrained due to the 
thermal, mechanical, and geochemical environment associated with an intrusion into an 
emplacement drift, igneous intrusion into the repository is Included within the TSPA-LA. The 
environmental conditions and their effect on waste packages are discussed in the FEP 
1.2.04.04.0A (Igneous intrusion interacts with EBS components). 
The TSPA-LA approach for addressing igneous intrusion is outlined in the document Total 
System Performance Assessment-License Application Method and Approach (BSC 2002, 
Section 8.1.2 [DIRS 160146]). The two igneous events (with individual probabilities and 
115 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
consequences) being modeled by the TSPA-LA are: 1) an igneous intrusion groundwater 
transport modeling case featuring the ascent of a basaltic dike or dike system (i.e., a set or swarm 
of multiple dikes comprising a single intrusive event) to the repository level where it intersects 
drifts; and 2) a volcanic eruption modeling case featuring the development of a volcano within 
the repository footprint with one or more conduits that intersect waste packages. As a 
consequence of the first event, which is non-eruptive, waste from breached packages may 
provide a source of radionuclides when groundwater moves through the damaged packages at 
some time in the future (igneous intrusion groundwater transport modeling case). The potential 
consequence of the second event (volcanic eruption modeling case) is that waste packages 
entrained within a conduit may be breached, releasing radionuclides in an erupting ash plume 
where they can be dispersed downwind to the RMEI. Based on the current design, the location is 
assumed approximately 18 km south of the repository (10 CFR 63.312 and 10 CFR 63.302, 
66 FR 55732 [DIRS 156671]). 
An appropriate analog for understanding the components of a volcanic event is the Paiute Ridge 
intrusive/extrusive center (Byers and Barnes 1967 [DIRS 101859]) on the northeastern margin of 
the Nevada Test Site. Paiute Ridge is a small-volume Miocene volcanic center comparable in 
volume and composition to Quaternary volcanoes near Yucca Mountain (CRWMS M&O 1998, 
p. 5-29 [DIRS 105347]). Paleomagnetic, geochronologic, and geochemical data indicate that the 
entire intrusive/extrusive complex formed during a brief magmatic pulse and, thus, represents a 
single volcanic event (Ratcliff et al. 1994 [DIRS 106634]; and CRWMS M&O 1998, p. 5-29 
[DIRS 105347]). The vents and associated dike system formed within a 
north-northwest-trending extensional graben provide excellent exposures of a variety of system 
depths including remnants of surface lava flows, volcanic conduits, and dikes and sills intruded 
into tuff country rock at depths of up to 300 meters (CRWMS M&O 1998, pp. 5-27 through 5-41 
[DIRS 105347]). There is evidence of shallow structural control of dike emplacement at Paiute 
Ridge, including dike emplacement along fault planes (Byers and Barnes 1967 [DIRS 101859]; 
and CRWMS M&O 1998, pp. 5-27 and5-28, [DIRS 105347]). Dike lengths at Paiute Ridge 
range from <1 km to 5 km (CRWMS M&O 1998, p. 5-31 [DIRS 105347]), comparable to the 
range estimated for post-Miocene volcanism near Yucca Mountain. 
The technical basis for the inclusion of this FEP is partially provided in Characterize Framework 
for Igneous Activity at Yucca Mountain, Nevada (BSC 2003 [DIRS 163769]). The analysis report 
documents the probability of a basaltic dike intersecting the repository footprint, the number of 
eruptive centers (conduits) within the repository footprint, and the length and azimuth of 
intersecting dikes within the repository footprint. The developed values represent full 
distributions, which are then used to generate a cumulative distribution function (CDF) of less 
than 100 points for the primary and contingency block values. 
The results of the probability analysis are used in the analyses of the number of waste packages 
hit during an igneous intrusion and affected by conduit formation. The distribution (CDF) of the 
number of waste packages hit is then used by the TSPA-LA model to determine the amount of 
waste released via an eruptive event and to determine the number of waste packages affected and 
the volume of waste subject to release via the groundwater pathway. For the igneous intrusion 
groundwater transport modeling case, all waste packages in intersected drifts are assumed to 
provide no further protection, and waste is available for release via normative groundwater flow 
and transport process. For the volcanic eruption modeling case, waste packages within the 
116 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
conduit diameter are assumed to release the waste to the surface via the conduit and an eruptive 
event. Because the CDF for the number of waste packages hit is dependent on the underlying 
inputs, the underlying inputs and related FEPs are considered included implicitly in the 
TSPA-LA model. Parameters developed in BSC 2003 (Sections 6.5.3.2 and 7.2 [DIRS 163769]) 
that are a direct output to the analysis report Number of Waste Packages Hit by Igneous Intrusion 
(BSC 2003 [DIRS 161851]), and that are implicitly included in the TSPA-LA, include the 
following: 
 Conditional joint probability distributions for length and azimuth of an intersecting dike 
within the repository LA footprintused to determine the distribution of dike azimuth 
angles, as basis for selection of 30-degree representation 
 Composite conditional probability distribution of the number of eruptive centers within 
the repository LA footprintused to determine the aggregate probability for number of 
conduits intersecting repository. 
Developed parameters from BSC 2003 (Section 7.2, [DIRS 163769]) that are direct outputs to 
and explicitly included in the TSPA-LA include the following: 
 A discrete probability distribution for the annual frequency of intersection of the 
proposed repository emplacement area footprint by a dike or dike system 
 A discrete probability distribution for the annual frequency of disruption of the proposed 
repository emplacement area footprint by one or more eruptive centers. 
The thermal, mechanical, and geochemical environments associated with an intrusion into an 
emplacement drift are governed in part by the properties of the magma and in part by the 
physical processes of volcanic intrusion. The analysis report Characterize Eruptive Processes at 
Yucca Mountain, Nevada (BSC 2003, Section 6 [DIRS 161838]) provides a partial technical 
basis for inclusion of the FEP in the TSPA-LA. The analysis report presents information about 
volcanic systems and the parameters that can be used to model their behavior. In particular, that 
report addresses the geometry of volcanic feeder systems, which is of primary importance in 
predicting how much of a repository would be affected by an eruption. The analysis report also 
addresses the physical and chemical properties of the magmas, which influence both eruptive 
styles and mechanisms for interaction with waste packages. 
The results of Characterize Eruptive Processes at Yucca Mountain, Nevada (BSC 2003, 
Table 37 [DIRS 161838]) do not directly feed into the TSPA-LA model. Rather, the results 
provide input for the following cited reports. Because the outputs of the cited reports are used 
either implicitly or explicitly in the TSPA-LA model, and the outputs of the cited reports are 
dependent on the underlying inputs documented in the eruptive processes analysis report (BSC 
2003 [DIRS 161838], the underlying inputs and related FEPs are considered to be implicitly 
included in the TSPA-LA model. The use of outputs is as follows: 
The model report Dike/Drift Interactions (BSC 2003, Table 2 [DIRS 165923]) uses the following 
outputs from the eruptive processes analysis report (BSC 2003, Table 37 [DIRS 161838]): 
117 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
 Velocity as a function of depthused to determine the magma far field velocity 
 Magmatic temperatures, viscosities, and densitiesused to determine the bulk density 
and bulk viscosity of magma, the magma vesicle free density, and intrusion temperature 
 Magma ascent rate below vesiculation depth and magma velocities 
 Dike widthused to determine the dike far field width. 
Number of Waste Packages Hit by Igneous Intrusion (BSC 2003, Table 4-1 [DIRS 161851]) also 
uses the output distributions from the eruptive processes analysis report (BSC 2003, Table 37 
[DIRS 161838] as addressed in FEPs 1.2.04.04.0A (Igneous intrusion interacts with EBS 
components) and 1.2.04.06.0A (Eruptive conduit to surface intersects repository). 
The primary factors of concern include the probability of the event occurring, the number of 
drifts and waste packages affected by the event, and the mechanism of radionuclide release to the 
accessible environment through a corresponding eruptive event or release via a groundwater 
pathway. The particular form of the intrusion (a dike, dike swarm or sill) is of lesser concern, so 
long as these differences are captured by the various parameter distributions and the event 
modeling allows for the intrusion of multiple drifts and damage of the waste packages within 
each of the intruded drifts. 
The form of the intrusion is addressed in the model report Dike/Drift Interactions (BSC 2003 
[DIRS 165923]), which considers the potential dike paths and dimensions in the dike 
propagation analysis. The dike propagation analyses use a numerical code based on a 
displacement-discontinuity boundary element formulation. The code includes all essential 
elements necessary for the simulation of hydraulic fracturing: fracture propagation, viscous fluid 
flow inside the fracture, and fluid leak-off in the surrounding formation. Fracture propagation is 
based on linearly elastic fracture mechanics. The approach is elastic and assumes plane strain 
conditions of deformation. The Dike Propagation model applies a fracture propagation approach 
using representative igneous dike properties to calculate key parameters such as dike width, dike 
pressure, and dike propagation velocity as the repository is approached and intersected. The 
sensitivity of the crack path to other model parameters (e.g., magma viscosity confining stress) 
and initial conditions (e.g., dike velocity at depth or driving pressure) also is considered. The 
model also uses a quantitative stress analysis to aid in evaluating how the stress field around the 
repository could influence the a basaltic igneous dikes direction of propagation and 
accommodates changing conditions along the pathway to which the dike may react, including the 
undisturbed area below the repository, the altered area around the repository and finally, 
conditions that apply as the dike continues upward after it has passed through the repository 
level. The input parameters for the model include the following: 
 Geographic/geologic: Regional topography, stratigraphy, in situ stresses, repository 
depth 
 Host rock properties: Youngs modulus, Poissons ratio, density, specific heat, thermal 
diffusivity, temperature 
118 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
 Magma properties: Density, latent heat, far-field velocity, intrusion temperature, solid 
fraction vs. temperature, specific heat, thermal diffusivity, pressure 
 Dike properties: Far-field width 
 Drift Properties: Repository layout, heat release, diameter, depth, spacing. 
The Dike Propagation model provides various outputs that are used as input parameters for the 
Magma and Gas Flow model and for assessing the formation of sills and secondary dikes. The 
Dike Propagation numerical model calculates and provides output to determine: 
 The fracture propagation tip location and fluid front location with time and with respect 
to the repository level 
 The magma pressure conditions and dike parameters with time at the point of intersection 
with the repository 
 The extent of the magma loss into the repository and its effect on subsequent dike growth 
 The change in confining stresses around the repository due to the presence of the dike. 
The output of the Dike Propagation model is not used directly in the TSPA-LA model, but is 
used to refine the conceptual model of dike propagation. The model report Dike/Drift 
Interactions (BSC 2003, Section 8.1 [DIRS 165923]) provides conclusions related to the effects 
of various factors such as stress states around the repository, topography effects, and thermal 
stresses on dike propagation. The model output also provides support for determining the 
potential for initiation of new fractures or reopening of existing joints inside the drift as a result 
of dike-drift interaction; the likelihood of the dike continuing on its path at the initial point of 
dike-drift intersection or its being diverted, and the selected boundary conditions (related to dike 
propagation) for leak-off of magma into a drift. The model does not provide results for a 
pyroclastic magma. In this way, the model implicitly defines the manner in which igneous 
intrusion into the repository is included in the TSPA-LA modelthat is, by defining the 
maximum length of an intersected drift that is involved in the direct flow path and providing 
input for the Magma and Gas Flow model. 
The output of this model provides the support for a conceptual dike propagation model that 
precludes an alternative conceptual model describing development of a conduit extending (or 
doglegging) from the point of drift intersection to the intersection of an eruptive conduit if the 
magma is effusive (i.e., does not expand rapidly). It also addresses the conditions pertaining to 
flow into drifts at the point of intersection if the magma is effusive. With regard to the 
dog-leg, the model report states in Section 8.1.2 (BSC 2003 [DIRS 165923] as follows: 
The dog-leg scenario of Woods et al. (2002 [DIRS 163662]) was evaluated for 
the non-explosive case of effusive flow, and that was not found to be credible. 
Based on an extensive simulation of crack-opening rates, the distance of the 
magma front from the drift periphery 300 s after magma has repressurized in the 
drift will be between 5 m and 60 m. However, in the same time, 300 s after the 
119 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
drifts are completely filled, magma flowing up the main dike would reach ground 
surface (assuming a magma front velocity of 1m/s). Under extreme conditions of 
10-MPa magma pressure inside the drift, the velocity of a magma front inside a 
joint is approximately 0.5 m/s (with a tendency to decrease as the pressure 
gradient decreases in response to the increasing length of the magma-filled 
portion of the joint), which is less than the expected velocity of the magma front 
inside the main dike. Analysis of the loss of heat from newly forming effusivemagma-
filled cracks in cold rock show clearly that such cracks will not be able to 
grow to any appreciable width before they are halted by solidification.  The 
igneous consequence Peer Review Final Report concludes that the dog-leg 
scenario, in which a new fracture or re-opening of a pre-existing fracture opens 
sufficiently wide enough and continues to propagate carrying magma to the 
surface, is highly unlikely, but that analyses need to be performed to demonstrate 
this conclusion. The analyses contained in this AMR clearly demonstrate that the 
dog leg scenario is highly unlikely for the case of effusive flow. The possibility 
of a dog-leg scenario of Woods et al. (2002 [DIRS 163662]) for the case of 
pyroclastic flow was acknowledged as an alternative conceptual model, but due to 
the unavailability of a qualified mathematical code at the time this report was 
prepared, no analysis is available to support similar conclusions regarding the 
pyroclastic dog leg. Nevertheless, it is highly unlikely that the pressures of a 
pyroclastic flow, while potentially greater than the rock strength, could sustain an 
open crack for a sufficient time to allow continuous flow of two-phase magma. 
Further analyses of pyroclastic flow using three-dimensional analyses will likely 
confirm this conclusion. 
Consequently, the dog-leg alternative conceptual model is not considered credible and is not 
further considered in the TSPA-LA. 
Related FEPs: 
FEPs that examine related but distinct effects and consequences 
Tectonic activitylarge scale (1.2.01.01.0A) 
Seismicity associated with igneous activity (1.2.03.03.0A) 
Igneous activity changes rock properties (1.2.04.02.0A) 
Magma or pyroclastic base surge transports waste (1.2.04.05.0A) 
Eruptive conduit to surface intersects repository (1.2.04.06.0A) 
Ashfall (1.2.04.07.0A) 
Diapirism (1.2.09.01.0A) 
Hydrologic response to igneous activity (1.2.10.02.0A) 
FEPs that examine similar effects and consequences: 
Igneous intrusion interacts with EBS components (1.2.04.04.0A) 
Related Documents: Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 (BSC 2003 [DIRS 163769]) 
120 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Supplemental Discussion: None 
6.2.2.3 Igneous Intrusion Interacts with EBS Components (1.2.04.04.0A) 
FEP Description: 
Descriptor Phrases: 
Screening Decision: 
Screening Argument: Not Applicable 
TSPA Disposition: 
Based on the results of Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
(BSC 2003, Section 6.5.3.2 and Table 22 [DIRS 163769]) the computed mean annual frequency 
of intersection of the repository footprint by a dike is 1.7  10-8 for the LA footprint (see 
Assumption 5.1 of this analysis report, ANL-WIS-MD-000005 REV. 01). This is based on the 
ANL-WIS-MD-000005 REV 01 
An igneous intrusion in the form of a dike occurs through the 
repository, intersecting the repository drifts. Magma, pyroclastics, 
and volcanic gases enter the drift and interact with the EBS 
components including the drip shields, the waste packages, pallet, 
and invert. This leads to accelerated drip shield and waste package 
failure (e.g., attack by magmatic volatiles, damage by flowing or 
fragmented magma, thermal effects) and dissolution or 
volatilization of waste. 
Igneous intrusion (drip shield damage), Igneous intrusion (waste 
package damage), Igneous intrusion (cladding damage), Chemical 
effects of igneous intrusion in EBS (solubility), Thermal effects of 
igneous intrusion in EBS 
[Note: This is a shared FEP. The scope and intent of this analysis 
report is to quantify the amplitude of the event to be considered. 
The full technical basis for these shared FEPs is addressed 
collectively by all of the sharing FEP AMRs. Descriptor phrases 
not addressed or only partially addressed in this report are further 
addressed in the sharing FEP AMRs.] 
Included (BSC 2003 Table 5 [DIRS 161838]; BSC 2003 Table 4 
[DIRS 165923]; BSC 2003, Table 3 [DIRS 161851]; BSC 2003, 
Table 6-1 [DIRS 165002]) 
The primary focus of this FEP is interactions between the 
intrusion, the waste, and the waste packages. These interaction 
are Included in the TSPA-LA because magma could interact with 
the elements of the EBS, and the waste packages could be impaired 
due to perturbations of the drift environment, thereby resulting in 
damage to the waste packages and mobilization of waste. 
121 
Characterize Eruptive Processes at Yucca Mountain, Nevada ANLMGR-
GS-000002 (BSC 2003 [DIRS 161838]) 
Dike/Drift Interactions 
MDL-MGR-GS-000005 (BSC 2003 [DIRS 165923]) Features, Events and Processes: Disruptive Events 
repository footprint presented in 800-IED-EBS0-00402-000-00B and 800-IED-EBS0-00401- 
000-00C (BSC 2003 [DIRS 161727, DIRS 162289]). The mean probability is used in the TSPALA 
to weight conditional dose calculations. Igneous intrusion into the repository (i.e., igneous 
activity) as provided in the FEP description, and as described for FEP 1.2.04.03.0A (Igneous 
intrusion into repository), has the potential to effect both the hydrologic and geochemical 
characteristics of the site, and due to extreme changes the in-drift environment, could damage EBS 
components and the waste packages. Combined, this could result in the release of radionuclides 
and affect the radiological exposure of the RMEI. 
Because the probability of igneous intrusion is slightly greater than the FEP screening probability 
threshold, and because waste package damage cannot be constrained due to the thermal, 
mechanical, and geochemical environment associated with an intrusion into an emplacement 
drift, igneous intrusion into the repository is included within the TSPA-LA. The environmental 
conditions and their effect on waste packages are discussed in this FEP 1.2.04.04.0A (Igneous 
intrusion interacts with EBS components). 
The TSPA-LA approach for addressing igneous intrusion is outlined in the document Total 
System Performance Assessment-License Application Method and Approach (BSC 2002, 
Section 8.1.2 [DIRS 160146]). The two igneous events (with individual probabilities and 
consequences) being modeled by the TSPA-LA are: 1) an igneous intrusion groundwater 
transport modeling case featuring the ascent of a basaltic dike or dike system (i.e., a set or swarm 
of multiple dikes comprising a single intrusive event) to repository level where it intersects 
drifts; and 2) a volcanic eruption modeling case featuring the development of a volcano within 
the repository footprint with one or more conduits that intersect waste packages. As a 
consequence of the first event, which is non-eruptive, waste from breached packages may 
provide a source of radionuclides when groundwater moves through the damaged packages at 
some time in the future (igneous intrusion groundwater transport modeling case). The potential 
consequence of the second event (volcanic eruption modeling case) is that waste packages 
entrained within a conduit may be breached, releasing radionuclides in an erupting ash plume 
where they can be dispersed downwind to the RMEI. Based on the current design, the location 
of the RMEI is assumed approximately 18 km south of the repository (10 CFR 63.312 and 
10 CFR 63.302, 66 FR 55732 [DIRS 156671]). 
This FEP is partially addressed, and the consequences constrained, by consideration of potential 
interaction of the drift and other EBS Components with magma flowing into an intersected drift. 
Properties and characteristics of basaltic magmas and basaltic eruptions are described in the 
analysis report Characterize Eruptive Processes at Yucca Mountain, Nevada (BSC 2001, Section 
6 [DIRS 161838]), and are based on the observed characteristics of past basaltic eruptions in the 
YMR and other analogous eruptions. These properties and characteristics are used as inputs and 
their significance discussed in the model report Dike/Drift Interactions (BSC 2003 
[DIRS 165923]). The Magma and Gas Flow Model discussed in Dike/Drift Interactions 
(BSC 2003 [DIRS 165923]) addresses conditions that could occur when unpressurized magma 
encounters a representative emplacement drift. The model uses standard design equations from 
hydraulic engineering to describe the flow of effusive (i.e., not pyroclastic) magma into a drift 
after magma has risen to repository level. In addition, one derived equation is used to account 
for viscous drag in the dike as magma flows into a drift. The model does not address pyroclastic 
flow of magma that is accelerating rapidly due to vapor expansion. The parameters used and/or 
122 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
developed in the model report related to this FEP include the following: 
 Geographic/geologic: Regional topography, stratigraphy, in situ stresses, repository 
depth 
 Host rock properties: Youngs modulus, Poissons ratio, density, specific heat, thermal 
diffusivity, temperature, pH, pore-water composition 
 Magma properties: Density, latent heat, far-field velocity, intrusion temperature, solid 
fraction vs. temperature, specific heat, thermal diffusivity, pressure 
 Dike properties: Far-field width 
 Drift Properties: Repository layout, heat release, diameter, depth, spacing, turnout 
dimensions Backfill properties: Friction angle, dilation, cohesion. 
The Magma and Gas Flow output as discussed in Section 8.1 of BSC 2003 [DIRS 165923] 
defines: 
 The environmental conditions (temperature, pressure, velocity of material, etc.) as a 
function of the distance from the point of dike intersection. 
 Distribution of magmatic products as a function of distance from the point of dike 
intersection. 
The model report Dike/Drift Interactions (BSC 2003, Section 8.1 [DIRS 165923]) provides 
conclusions related to various factors influencing post-intrusion environmental conditions within 
the drifts. The outputs of the model indicated that the entire length of an intersected drift has the 
potential to be filled, at least partially, with magmatic materials. The temperature history outputs 
from the Magma and Gas Flow model suggest that any waste package in contact with either 
magma or pyroclastic materials will be exposed to conditions at or near thermal limitations of the 
waste package materials. 
The resulting damage mechanisms and extent of damage are further examined in the model 
report Igneous Intrusion Impacts on Waste Package and Waste Form (BSC 2003 
[DIRS 165002]) and lead to an assumption of no further protection being afforded by the waste 
packages in intersected drifts. The potential for damage to waste packages and waste forms from 
heat and migrating gas is examined in the cited model report (BSC 2003, [DIRS 165002]). That 
modeling effort leads to a conclusion that the properties of the host rock and the presence of 
backfill at the ends of the drifts preclude damage in non-intersected drifts from heat and gas 
migration from intersected drifts. The fractured and porous rock, as well as the crushed tuff used 
to backfill the perimeter drifts, represents a possible path for gas flow resulting from magma. 
However, gas movement through the backfill is slower than the rock matrix and does not move 
as far as the flow in the rock matrix (BSC 2003, Section 6.5.2.2.3 [DIRS 165002]). For a given 
gas flux rate, the pore velocity of gas moving through a less porous material is faster because the 
flow of gas occurs through a smaller area. This difference can be attributed to the difference in 
porosity between the two materials (host rock porosity = 0.154, backfill porosity = 0.545). In 
both cases, the velocity approaches zero around one year. As the pressure equilibrates to less 
123 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
than 10 atmospheres, the gas flow rate decreases. The gas front eventually stops at around 3.6 
meters in the host rock and 1.4 meters in the backfill (BSC 2003, Section 6.5.2.2.3 [DIRS 165002]). 
While advective gas flow is one component of movement between the drifts during the first year, 
diffusion is still occurring and becomes the single mode of gas movement at some point during 
gaseous equilibration. Results from the analyses of gaseous diffusion from the magma filled 
emplacement drift show that the gas concentrations entering the adjacent Zone 2 emplacement 
drifts, would be low and begin to significantly reduce after about two years (BSC 2003, 
Section 6.5.2.2.3 [DIRS 165002]). These results indicate that the waste packages in Zone 2 
emplacement drifts would not be impacted by the volatile gases exsolving from the basalt 
magma and intruded into Zone 1 emplacement drifts. 
The resulting environmental conditions and resultant damage states for the intruded drifts are 
passed to the TSPA-LA model, and in combination with the results of the analysis report Number 
of Waste Packages Hit by Igneous Intrusion (BSC 2003 [DIRS 161851]), are used to determine 
the source term for calculating igneous-related dose. 
The analysis provided in Number of Waste Packages Hit by Igneous Intrusion (BSC 2003 
[DIRS 161851]) uses repository design information and outputs from the revisions of the analysis 
reports Characterize Framework for Igneous Activity at Yucca Mountain, Nevada (BSC 2003 
[DIRS 163769]), and Characterize Eruptive Processes at Yucca Mountain, Nevada (BSC 2003 
[DIRS 161838]) to calculate the number of waste packages exposed to Zone 1 (intersected drifts) 
magmatic environments. The analysis uses spreadsheet calculation operations to evaluate 
geometric relationships between dike intersection area and conduit geometry and the number of 
waste packages impacted by dikes and conduits. The types of information used include: 
 Repository design information (repository area, drift diameter, drift spacing, waste 
package length, and waste package spacing) 
 Igneous event probability 
 Probability distributions and parameters associated with dikes within the repository (dike 
length, dike azimuth angle, dike width, and number of dikes in a swarm). In particular it 
uses: 
 Dike-widthused to determine maximum dike width 
 Number of dikes associated with formation of a new volcanoused to determine the 
maximum number of dikes in a swarm, and the distribution type for the number of 
dikes in a swarm 
 Dike spacingused to determine dike spacing within a swarm. 
The parameters developed in BSC 2003 [DIRS 161851] related to this FEP include: 
 Probabilities for dike-swarm configurations 
 Dike swarm interaction with repository drifts. 
124 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
The number of waste package analysis results (BSC 2003 [DIRS 161851] include CDFs for the 
number of waste packages hit in an igneous intrusion scenario and in an eruptive release 
scenario. These CDFs are used directly and explicitly in the TSPA-LA model to determine the 
source term for the igneous event scenarios. Because the CDFs are dependent on the underlying 
inputs, the underlying inputs and related FEPs are considered implicitly included in the 
TSPA-LA model. 
The interaction of the magma with the waste form is further examined in the model report 
Igneous Intrusion Impacts on Waste Package and Waste Form (BSC 2003 [DIRS 165002]). 
That model report takes feeds from the analysis report Characterize Eruptive Processes at Yucca 
Mountain, Nevada (BSC 2003 [DIRS 161838]) in the form of: 
 Magma chemistryused to determine the mean chemical composition of basalt 
 Gas compositionused to determine total moles of exsolving gases 
 Water content of magmaused for bound the water content of basaltic magma 
 Magmatic temperatures, viscosities, and densitiesused to define basaltic characteristics 
and to define initial intrusive magma conditions. 
The information developed in BSC 2003 [DIRS 165002] supports the use of the TSPA 
assumption that waste packages in Zone 1 emplacement drifts no longer provide protection for 
the waste forms. The fuel, glass, and other waste would be entrained into the magma. With 
regard to the igneous intrusion groundwater transport modeling case, no credit is taken for partial 
protection that residual elements of the waste package shells and the encapsulating basalt will 
provide. This is because quantification of these positive effects would be highly uncertain. In 
the intruded drifts, cooling joints would likely form in the basaltic magma during cooling, and 
some subsequent exposure to groundwater will occur. Dissolution of waste in basaltic melt is 
not considered explicitly, but is conservatively bounded by the presumption that waste is 
exposed directly to groundwater without any protection from the surrounding basalt. The 
subsequent movement of radionuclides in groundwater is then modeled directly in the TSPA-LA 
using the existing flow-and-transport models used for the nominal scenario. Accordingly, the 
transport would be dependent on the solubility limits of the exposed waste and the availability of 
groundwater as modeled for the nominal case. The TSPA-LA approach for addressing igneous 
intrusion is outlined in the document Total System Performance Assessment-License Application 
Method and Approach (BSC 2002, Section 8.1.2 [DIRS 160146]). 
With regard to the volcanic eruption modeling case, the model report Atmospheric Dispersal and 
Deposition of Tephra from a Potential Volcanic Eruption at Yucca Mountain, Nevada 
(BSC 2003 [DIRS 161840] provides the technical basis for assuming erupted materials are finely 
divided particles amenable for airborne transport (BSC 2003, Section 6.5.2.17 [DIRS 161840]). 
The technical basis for the fragmented fuel particle size is contained in the Miscellaneous Waste 
Form FEPs (CRWMS M&O 2001, Attachment I [DIRS 153938]). 
The results of the igneous impact model report (BSC 2003 [DIRS 165002]) and the number of 
waste packages analysis report (BSC 2003 [DIRS 161851]) are used directly in the TSPA-LA. 
Consequently, this FEP is considered as implicitly included for damage state and changes in 
125 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
waste form by assuming that the waste packages in intersected drifts provide no further 
protection for waste, and that the waste is assimilated in magma. It is explicitly included using a 
probabilistic treatment regarding the number of waste packages damaged. 
Related FEPs: 
FEPs that examine related but distinct effects and consequences: 
Ashfall (1.2.04.07.0A) 
Seismicity associated with igneous activity (1.2.03.03.0A) 
Mechanical impact on waste package (2.1.03.07.0A) 
Mechanical impact on drip shield (2.1.03.07.0B) 
Flow through seals (access ramps and ventilation shafts) (2.1.05.01.0A) 
Degradation of seals (2.1.05.03.0A) 
Mechanical degradation of pallet (2.1.06.05.0A 
Mechanical degradation of invert (2.1.06.05.0B) 
Effects of drip shield on flow (2.1.06.06.0A) 
Thermal sensitization of waste packages (2.1.11.06.0A) 
Thermal sensitization of drip shields (2.1.11.06.0B) 
Thermal expansion/stress of in-package EBS components (2.1.11.05.0A) 
Thermal expansion/stress of in-drift EBS components (2.1.11.07.0A) 
Thermally-induced stress changes in the near field (2.2.01.02.0A) 
FEPs that examine similar consequences and events 
Igneous intrusion into the repository (1.2.04.03.0A) 
Magma or pyroclastic base surge transports waste (1.2.04.05.0A) 
Eruptive conduit to surface intersects repository (1.2.04.06.0A) 
Characterize Eruptive Processes at Yucca Mountain, Nevada Related Documents: 
ANL-MGR-GS-000002 (BSC 2003 [DIRS 161838]) 
Dike/Drift Interactions 
MDL-MGR-GS-000005 (BSC 2003 [DIRS 165923]) 
Number of Waste Packages Hit by Igneous Intrusion 
ANL-MGR-GS-000003 (BSC 2003 [DIRS 161851]) 
Igneous Intrusion Impacts on Waste Package and Waste Form 
MDL-EBS-GS-000002 (BSC 2003 [DIRS 165002]) 
Supplemental Discussion: None 
6.2.2.4 Magma or Pyroclastic Base Surge Transports Waste (1.2.04.05.0A) 
FEP Description: As a result of the igneous intrusion, extrusive processes result in a 
pyroclastic density flow, base surge, dike apron, effusive lava 
flows and/or development of a volcanic vent at land surface. 
126 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Some of the waste (entrained, dissolved, or volatized) is then 
transported away from the repository. Of most concern is transport 
directly along the land surface to the RMEI. 
Descriptor Phrases: Entrainment of waste in magma, Dissolution of waste in magma, 
Volatilization of waste in magma, Transport of waste to surface in 
liquid magma 
Excluded.Low Consequence Screening Decision: 
Screening Argument: This FEP is focused on near-surface eruption-related phenomena 
and on magmatic-related transport of entrained wastes. 
Hydro-volcanic phenomena also are addressed under this FEP and 
due to the distance to the RMEI, and as supported by the low 
probability of a maar crater extending to the repository depth and 
exhuming waste, hydrovolcanic phenomena have been excluded 
based on low consequence. Incorporation and transport directly to 
the receptor biosphere via an ashplume and/or subsequent 
reworking of the deposited ash following an eruptive event is 
addressed separately in FEP 1.02.04.07.0A (Ashfall), and its 
companion FEP 1.02.04.07.0C (Ash redistribution via soil and 
sediment transport). 
Table 22 of Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
(BSC 2003 [DIRS 163769]) indicates that the annualized frequency of one or more eruptive 
centers with the repository footprint is 1.3 x 10-8 (see Assumption 5.1 of this analysis report, 
ANL-WIS-MD-000005 REV. 01). This is based on the repository footprint presented in 
800-IED-EBS0-00402-000-00B and 800-IED-EBS0-00401-000-00C (BSC 2003 [DIRS 161727, 
DIRS 162289]). However, the geographical extent of magmatic and pycroclastic base surge 
events is insufficient to reach the location of the RMEI, so the FEP is Excluded. 
The definitions of accessible environment, controlled area and reference biosphere as 
described in Section 4.1.3.1 of this report (ANL-WIS-MD-000005 REV 01) indicate the 
distances of concern for the RMEI. These definitions and concepts indicate that the RMEI is 
located no closer than 18 km to the south in the direction of groundwater flow and over a 
contaminated groundwater plume, and that the limit of the controlled area is no greater than 5 km 
from the repository in any other direction (10 CFR 63.312 and 10 CFR 63.302, 66 FR 55732 
[DIRS 156671]). 
By contrast, all of the Quaternary volcanoes in the vicinity of Yucca Mountain are similar in that 
they are of small volume (~0.1 km3 or less) and typically consist of a single main scoria cone 
surrounded by a small field of aa basaltic flows, which commonly extend approximately 1 km 
from the scoria cone (Characterize Framework for Igneous Activity at Yucca Mountain, Nevada, 
BSC 2003, Section 6.2 [DIRS 163769]). Consequently, it is not credible to presume that 
extruded basalts with entrained wastes will extend to the RMEI located 18 km south of the 
repository. 
127 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Pyroclastic deposits consist of a wide range of materials, transport mechanisms and depositional 
environments. The total eruption volume of the post-Miocene basalts is about 6 km3. The 
volume of individual episodes has decreased progressively through time, with the three Pliocene 
episodes having volumes of approximately 1 to 3 km3 each and the three Quaternary episodes 
having a total volume of approximately 0.5 km3. The pyroclastic deposits and associted volume 
of material indicate that pyroclastic eruptive mechanisms associated with strombolian eruption 
may result in transport of pyroclastic tephra (e.g., lapilli and ash) particles at distances sufficient 
to reach the RMEI. This aspect of an eruptive scenario has been included and is addressed 
separately in FEP 1.02.04.07.0A (Ashfall), and its companion FEP 1.02.04.07.0C (Ash 
redistribution via soil and sediment transport). Differential settling due to ash density is 
addressed in the eruptive scenario. 
Of particular interest for this FEP, are hydrovolcanic deposits and pyroclastic surge deposits. 
Hydrovolcanic deposits consist of mostly ash deposited in density currents (surges), leaving 
distinctive thin planar beds and cross-beds. Pyroclastic surge deposits at Lathrop Wells cone 
have been observed and inferred to represent hydrovolcanic eruption during the early states of 
the evolution of the basalt center. A detailed description of deposits at a stratigraphic section 
(hydrovolcanic) located at N36 41 42.7, W116 30 53.5, at an elevation of 863.8 meters 
(2834 ft), located 0.7 km NW of the summit of Lathrop Wells cone, is provided in Characterize 
Eruptive Processes at Yucca Mountain, Nevada (BSC 2003, Section 6.4.2.3 [DIRS 161838]) 
along with the description of other surrounding hydrovolcanic deposits. As noted in BSC 2003 
([DIRS 161838]), these ash beds have been interpreted as hydrovolcanic in origin (pyroclastic 
surge deposits of Vaniman and Crowe (1981, pp. 20C21 [DIRS 101620]); and Wohletz (1986, p. 
258 [DIRS 140956])). Within the area flanked by the cinder cone and the protruding ridge of 
Miocene tuff, there is a transition southward, over a distance of approximately 400 meters, from 
thousands of thin beds of hydrovolcanic facies to hundreds, and eventually to one or two 
resistant ash beds sandwiched between coarse lapilli beds. Observations in trenches immediately 
southwest of the cone also indicate a southward thinning hydrovolcanic sequence. BSC 2003 
(Section 6.4.2.3 [DIRS 161838]) notes that the field relations suggest that the limited deposit 
resulted from a ground-hugging sector blast directed to the northwest. Because the unit slopes 
approximately 8 degrees back toward the cone and projects to beneath the cone base, the exact 
relations are covered, but there are currently no field data confirming a concentric tuff ring 
(Wohletz 1986, p. 262 [DIRS 140956]). At the Lathrop Wells scoria cone, about 6 meters below 
the south summit (elevation 954 m), there is a 40-cm thick, well-sorted, finely bedded, crossbedded 
ash and coarse ash deposit. This deposit appears to be the result of a brief hydrovolcanic 
event late in the cone-building history (BSC 2003, Section 6.4.1.1 [DIRS 161838]). Crowe et al. 
(1986, pp. 32-34 [DIRS 101532] referenced in DTN: MO0310INPDEFEP.000 [DIRS 165880]) 
identified similar features, along with pyroclastic surge deposits for the southern and middle 
centers of the basalts of Nye Canyon. The Nye Canyon features were on the scale of 1 km or 
less. 
Given the lateral scale of the observed hydrovolcanic deposits on the order of 1 km or less, it is 
not credible to presume that pyroclastic base surges with entrained wastes will reach the RMEI 
located 18 km south or to the control area boundaries at no greater than 5 km in other directions. 
Another concern is the possibility that a large steam explosion could occur, such that a large 
phreatic or a phreatomagmatic crater (maar) might form. Such a process could directly excavate 
128 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
waste and disperse it over a large area of the surrounding surface. Hydrovolcanic activity 
requires that rising magma encounter water in an aquifer(s) or a shallow water body at the 
ground surface (Fisher and Schmincke 1984, pp. 231-264 [DIRS 162806]; Wohletz and Heiken 
1992, pp. 85154 [DIRS 105544]). The resulting steam explosion finely fragments the magma 
and produces large amounts of kinetic energy. If the encounter occurs below the ground surface, 
the host rocks are highly fractured and the eruption products are elevated in lithic clasts. For a 
large, disruptive steam explosion to occur, magma must come in rapid contact with a large 
volume of water at a shallow depth. Confining pressures must be sufficiently low to permit the 
formation of steam, and, as the steam violently expands, to allow disruption of the surrounding 
rock. Crowe et al. (1986, p. 47 [DIRS 101532]) suggest that a limited area of contact, such as a 
dike projecting through a thin (<10 m) aquifer, does not allow development of explosive 
instability, whereas contact with a standing body of water or thick (>30 m) horizon of 
water-saturated rock permits water to vaporize at explosive rates. They also suggest that 
magma/water mixing and explosion associated with maars, tuff rings, and tuff cones generally 
occur at depths less than 200 meters, which corresponds to 5 MPa or less, but also acknowledge 
that deeper aquifers contribute to hydroexplosions as well. They note, however, that deep 
interaction at confining pressures above the critical point of water probably involves a different 
set of explosive mechanisms. 
Crowe et al. (1986, Figure 19 [DIRS 101532] referenced in DTN: MO0310INPDEFEP.000 
[DIRS 165880]) present a plot of the relative-frequency of crater depth for known hydrovolcanic 
craters, maars, and tuff rings. The plot is positively skewed with a mean of 91 + 67 m, and the 
maximum crater depth is plotted at approximately 365 meters. Crowe et al. (1986, pp. 58-59 
[DIRS 101532]) conclude that exhumation of a repository by explosive cratering associated 
with water/magma interaction is unlikely.the depth of burial of a repository at Yucca Mountain 
exceeds the crater depth of the largest known hydrovolcanic craters. However, this was based 
on an assumed repository depth of 380 meters. The mean crater depth for hydrovolcanic craters 
is 91 meters, which is insufficient to exhume to the repository depth, within an uncertainty of one 
standard deviation. 
The minimum depth of the TSPA-LA repository (distance from the emplacement area to the 
overlying surface) is approximately 211 meters. The elevation along the eastern edge of the 
repository, with the exception of topographic relief in drainages and washes, is on the order of 
1250 to 1280 meters (4,100 to 4,200 ft) . Drawing 800-IED-EBS0-00401-000-00C (BSC 2003 
[DIRS 162289]), in comparison to Figure 1 of BSC 2002 [DIRS 159124], indicates that the 
easternmost drifts are in the area of lowest ground surface elevations and include drifts 2-1E 
through 2-19E. Drawing 800-IED-EBS0-000402-000-000-00B (BSC 2003 [DIRS 161727]) 
indicates that the endpoint elevations for these drifts varies from 1042 meters for Drift 2-1E to as 
high as 1063 meters for Drift 2-19E. This suggests a difference in elevation (or depth to the 
repository) of 208 meters to 238 meters. A more detailed analysis can be had by scaling the endpoints 
of the drifts from the grid presented in Drawing 800-IED-EBS0-00401-000-00C (BSC 
2003 [DIRS 162289] and subtracting the corresponding end-drift elevations from the nearest 
topographic grid point provided in DTN: MO0002SPATOP00.001 [DIRS 152643]. The 
northernmost and southernmost drifts were selected based on minimum and maximum drift 
elevations in the eastern part of the repository, and Figure 1 of BSC 2002 [DIRS 159124] and 
DTN: MO0002SPATOP00.001 [DIRS 152643] was inspected to determine where the deepest 
draw and lowest elevation of the topographic grid occurred within the repository footprint. The 
129 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
comparison of elevations is shown in Table 6-5. 
Table 6-5. Calculation of Shallowest Depth of Waste Emplacement Drifts 
Nearest Topographic Grid Point 
Northing 
Location Approximate Approximate 
Easting 
East end of Drift 2-1E 775,000 
775,000 
565,500 
565,600 
Difference in Elevation 
East end of Drift 2-12 E 
Nearest Topographic Grid Point 
771,300 
771,300 
1055 m 
1267 m (4154 ft) 
212 m Difference in Elevation 
East end of Drift 2-19E 
Nearest Topographic Grid Point 
769,300 
769,300 
1063 m 
1283 m (4208 ft) 
220 m Difference in Elevation 
Note: Drift end coordinates on are in feet and are State Plane Coordinates. They are considered approximate 
because they were manually scaled from Figure 800-IED-EBSO-00401-000C (BSC 2003 [DIRS 162289]) 
to allow comparison with data from DTN: MO0002SPATOP00.001 [DIRS 152643], which is also in State 
Plane Coordinates. The end drift coordinates given in 800-IED-EBS0-000402-000-00B (BSC 2003 
161727]) are given in meters rather than feet and are not readily comparable to the State Plane 
Coordinates. 
The calculated minimum value could be in error by as much as 10 meters as it is based on only 
the three selected points. The minimum value of 211 meters is corroborated with a stated 
corroborating value of 215 meters of overburden above the waste emplacement area as indicated 
in 800-P0C-MGR0-00100-000-00E (BSC 2003, Section 7.1.8 [DIRS 165572]). For a greater 
than 215-meter crater depth, the relative frequency of occurrence is less than 15 percent (Crowe 
et al., Figure 19 [DIRS 101532] as referenced in DTN: MO0310INPDEFEP.000 
[DIRS 165880]), and an assumption of less than 15 percent occurrence is appropriate for crater 
depths of greater than 148 meters (15 percent is the relative percent occurrence at the mean value 
of 91 meters, and 148 meters is the mean value plus one standard deviation of 57 meters). 
Furthermore, the hydrovolcanic event is conditional on a geologic setting conducive to a 
hydrovolcanic event. Consequently, the net probability of occurrence of a 215-meter 
hydrovolcanic crater associated with intrusion of the repository falls below the FEPs screening 
probability threshold. This assertion is based on an assumed probability of 15 percent for a 
hydrovolcanic eruption resulting in a crater depth of 215 meters or greater, an assumed 
independence of a hydrovolcanic explosion from a conditional dike intrusion into the repository, 
and calculated values of 1.3 x 10-8 for the mean probability of an eruptive center forming within 
the repository footprint. 
Additionally, the distribution of existing hydrovolcanic deposits is limited to a radius on the 
order of 1 km or less, which is insufficient to reach the controlled area boundary, and the 
TSPA-LA includes a volcanic eruption modeling case that distributes ash to the location of the 
RMEI. Consequently, the transport by a hydrovolcanic cratering event as a separate modeling 
case can be Excluded based on low consequence. 
ANL-WIS-MD-000005 REV 01 130 
Elevation (m) 
1042 m 
1262 m (4141 ft) 
564,100 
564,100 
563,500 
563,500 
Depth of 
Repository 
(m) 
220 m Features, Events and Processes: Disruptive Events 
TSPA Disposition: 
Related FEPs 
FEPs that examine related but distinct effects and consequences. 
Igneous intrusion into repository (1.2.04.03.0A) 
Eruptive conduit to surface intersects repository (1.2.04.06.0A) 
Ashfall (1.2.04.07.0A) 
Ash redistribution via soil and sediment transport (1.2.04.07.0C) 
Hydrologic response to igneous activity (1.2.10.02.0A) 
FEPs that examine similar effects and consequences 
Igneous intrusion interacts with EBS components (1.2.04.04.0A) 
Related Documents: Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
Supplemental Discussion: None 
6.2.2.5 Eruptive Conduit to Surface Intersects Repository (1.2.04.06.0A) 
FEP Description: 
Descriptor Phrases: 
Screening Decision: 
Screening Argument: 
TSPA Disposition: 
Igneous intrusion into the repository (i.e., igneous activity) as provided in the FEP description is 
described for FEP 1.2.04.03.0A (Igneous intrusion into repository). Table 22 of Characterize 
ANL-WIS-MD-000005 REV 01 
As a result of an igneous intrusion, one or more volcanic vents 
forms at land surface. The conduit(s) supplying the vent(s) 
pass(es) through the repository, interacting with and entraining 
waste. 
Conduit (vent) to surface intersects drift, Entrainment of waste in 
ash in conduit (vent), Transport of waste to surface in ash 
Included (BSC 2003 Table 5 [DIRS 161838]; BSC 2003 Table 3 
[DIRS 161851]; BSC 2003, Table 6 [DIRS 161840]) 
Not Applicable 
Eruptive Conduit to Surface Intersects Repository is Included in 
the TSPA-LA and is addressed through the modeling of an eruptive 
event. Consequences of an igneous intrusion through the 
repository and a resulting eruptive event are explicitly Included in 
the TSPA-LA, and appropriately weighted by the probability of 
occurrence of the event. 
131 
Not Applicable 
ANL-MGR-GS-000001 (BSC 2003 [DIRS 163769]) 
Characterize Eruptive Processes at Yucca Mountain, Nevada 
ANL-MGR-GS-000002 (BSC 2003 [DIRS 161838]) Features, Events and Processes: Disruptive Events 
Framework for Igneous Activity at Yucca Mountain, Nevada (BSC 2003 [DIRS 163769]) 
provides a separate annualized frequency of one or more eruptive centers with the repository 
footprint of 1.3 x 10-8 (see Assumption 5.1 of this analysis report, ANL-WIS-MD-000005 REV. 
01). This is based on the repository footprint presented in 800-IED-EBS0-00402-000-00B and 
800-IED-EBS0-00401-000-00C (BSC 2003 [DIRS 161727, DIRS 162289]). Additionally, the 
lateral extent of ashfall from such an event is sufficient to reach the location of the RMEI, so the 
FEP has been Included. 
The TSPA-LA approach for addressing igneous intrusion is outlined in the document Total 
System Performance Assessment-License Application Method and Approach (BSC 2002, 
Section 8.1.2 [DIRS 160146]). The two igneous events (with individual probabilities and 
consequences) being modeled by the TSPA-LA are: 1) an igneous intrusion groundwater 
transport modeling case featuring the ascent of a basaltic dike or dike system (i.e., a set or swarm 
of multiple dikes comprising a single intrusive event) to the repository level where it intersects 
drifts; and 2) a volcanic eruption modeling case featuring the development of a volcano within 
the repository footprint with one or more conduits that intersect waste packages. As a 
consequence of the first event, which is non-eruptive, waste from breached packages may 
provide a source of radionuclides when groundwater moves through the damaged packages at 
some time in the future (igneous intrusion groundwater transport modeling case). The potential 
consequence of the second event (volcanic eruption modeling case) is that waste packages 
entrained within a conduit may be breached, releasing radionuclides in an erupting ash plume 
where they can be dispersed downwind to the RMEI. Based on the current design, the location 
of the RMEI is approximately 18 kilometers (km) south of the repository (10 CFR 63.312 and 
10 CFR 63.302, 66 FR 55732 [DIRS 156671]). 
Properties and characteristic of the basaltic eruption are described in Characterize Eruptive 
Processes at Yucca Mountain, Nevada (BSC 2003, Section 6 [DIRS 161838]). The eruption 
characteristics used in the TSPA-LA model are based on the observed characteristics of past 
basaltic eruptions in the YMR and other analogous eruptions. For the volcanic eruption 
modeling case, a dike rises to the repository level, intersects one or more drifts in the repository, 
and proceeds toward the surface. Conduits develop from the surface downward within the 
repository footprint. Conduits within the repository footprint are presumed in the TSPA-LA to 
be located randomly along intersecting dikes. It is presumed for the volcanic-eruption-scenario 
analysis in the TSPA-LA that waste in waste packages, as well as other components of the EBS 
that will be breached by igneous activity, are available to be entrained in dike material. Where 
conduits intersect drifts, waste packages in intersected drifts are presumed to no longer provide 
protection for the waste. Waste material in these waste packages is entrained in a pyroclastic 
eruption. The model report Atmospheric Dispersal and Deposition of Tephra from a Potential 
Volcanic Eruption at Yucca Mountain, Nevada provides the technical basis for assuming erupted 
materials are finely divided particles amenable for airborne transport (BSC 2003, Section 
6.5.2.17 [DIRS 161840]). The technical basis for the fragmented fuel particle size is contained 
in the Miscellaneous Waste Form FEPs (CRWMS M&0 2001, Attachment I [DIRS 153938]). 
The conduit supplies a mass of ash and waste to the eruption occurring at the land surface of the 
mountain. It is presumed for the referenced analysis that all intrusive events contain an eruptive 
phase and produce a conduit venting to land surface. The bases for these assumptions about 
132 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
eruptive process and their effects are addressed by other igneous-related model or scientific 
analysis reports listed in Table 6-3 of this analysis report (ANL-WIS-MD-000005 REV 01). 
As previously described for FEP 1.2.04.03.0A (Igneous intrusion into repository), the model 
report Dike/Drift Interactions (BSC 2003 [DIRS 165923]) provides conclusions related to 
various conceptual models for magma flow in drifts, including consideration of the dog-leg 
scenario. The dog-leg scenario is discussed in Section 8.1.2 of the model report (BSC 2003 
[DIRS 165923], as its disposition is addressed in Section 6.2.2.2 of this analysis report 
(ANL-WIS-MD-000005 REV 01) for FEP 1.2.04.03.0A (igneous intrusion intersects repository). 
The analysis report Characterize Eruptive Processes at Yucca Mountain, Nevada (BSC 2003 
[DIRS 161838]) provides a technical basis for inclusion of the FEP in the TSPA-LA. That 
analysis report includes the results of field investigations dealing with physical volcanology and 
describes the conceptual models for eruptive processes including conduit formation. This 
information is used to develop parameter value distributions appropriate for evaluation of the 
related FEPs and analysis of the consequences of volcanic eruptions through a proposed 
repository at Yucca Mountain, Nevada. In particular, that analysis report addresses the following 
aspects of the FEP: 
 The geometry of volcanic feeder systems, which is of primary importance in predicting 
how much of a repository LA footprint would be affected by an eruption 
 The physical and chemical properties of the magmas, which influence both eruptive 
styles and mechanisms for interaction with waste packages 
 Eruptive processes, including the ascent velocity of magma at depth, the onset of bubble 
nucleation and growth in the rising magmas, magma fragmentation, and velocity of the 
resulting gas-particle mixture. 
The parameters related to this FEP that are developed in the eruptive processes analysis report 
include the following output distributions (BSC 2003, Table 37 [DIRS 161838]): 
 Conduit diameter 
 Eruptive power 
 Duration of a single explosive phase constituting a violent strombolian eruptive phase 
 Eruption duration for formation of an entire volcano 
 Eruption volume 
 Velocity as a function of depth. 
The results documented in Characterize Eruptive Processes at Yucca Mountain, Nevada 
(BSC 2003 [DIRS 161838]) do not directly feed the TSPA-LA model. Rather, the results 
provide inputs for the reports identified in the following paragraphs. Because the outputs of the 
identified reports are used either implicitly or explicitly in the TSPA-LA model, and the outputs 
of the listed reports are dependent on the underlying inputs documented in this analysis report, 
the underlying inputs and related FEPs are considered to be implicitly included in the TSPA-LA 
model. 
133 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
The analysis report Number of Waste Packages Hit by Igneous Intrusion (BSC 2003 
[DIRS 161851]) provides parameters to the TSPA-LA that addresses this FEP. The types of 
information used include: 
 Repository design information (repository area, drift diameter, drift spacing, waste 
package length, and waste package spacing) 
 Igneous event probability 
 Probabilities and parameters associated with conduits occurring within the repository 
(conditional probability that more than one conduit will occur within the repository 
footprint and conduit diameter distributions). 
The analysis (BSC 2003 [DIRS 161851]) uses the outputs from the revision of the analysis report 
Characterize Framework for Igneous Activity at Yucca Mountain, Nevada (BSC 2003 
[DIRS 163769]), including: 
 Conditional joint probability distributions for length and azimuth of an intersecting dike 
system, within the repository LA footprintused to determine the distribution of dike 
azimuth angles, as basis for selection of 30 degree representation 
 Composite conditional probability distribution of the number of eruptive centers within 
the repositoryused to determine the aggregate probability for number of conduits 
intersecting repository. 
The analysis also uses the outputs from the revision of Characterize Eruptive Processes at Yucca 
Mountain, Nevada (BSC 2003 [DIRS 161838]): 
 Conduit diameterused to determine the conduit diameter distribution, modal conduit 
diameter, the maximum conduit diameter, and minimum conduit spacing. 
For the volcanic eruption modeling case, the analysis (BSC 2003 [DIRS 161851]) provides a 
CDF for number of waste packages hit by an eruptive conduit. The CDF is based on a 
relationship between the resulting conduit areas and the fraction of the repository area occupied 
by waste packages. This relationship was used in conjunction with a joint distribution 
incorporating the variability in eruptive conduit diameters and in the number of eruptive conduits 
that could intersect the repository, to the calculated resulting CDF. The CDF is used directly by 
the TSPA-LA for the volcanic eruption modeling case featuring the development of a volcano 
within the repository footprint with one or more conduits that intersect waste packages. Because 
the CDF is dependent on the underlying inputs, the underlying inputs and related FEPs are 
considered implicitly included in the TSPA-LA model. 
The modeling of the eruptive event is outlined in the model report Atmospheric Dispersal and 
Deposition of Tephra from a Potential Volcanic Eruption at Yucca Mountain, Nevada 
(BSC 2003 [DIRS 161840]). The TSPA-LA model, using ASHPLUME V 2.0, estimates 
radionuclide concentrations in contaminated ash falling at the location of the RMEI, 
approximately 18 km south of the repository. For the volcanic eruption modeling case, the 
TSPA-LA presumes that a hypothetical violent strombolian eruption occurs through a section of 
134 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
the repository, entraining radionuclide-bearing wastes in the ash plume that disperses downwind 
and deposits contaminated ash on the ground surface. 
The output from the eruptive processes analysis report (BSC 2003, Table 37 [DIRS 161838]) is 
used in the model report Atmospheric Dispersal and Deposition of Tephra from a Potential 
Volcanic Eruption at Yucca Mountain, Nevada (BSC 2003, Table 8 [DIRS 161840]) as input for 
developing the following parameters: 
 Mean ash particle diameter 
 Mean ash particle diameter standard deviation for particle size distribution 
 Ash particle shape factor 
 Ash particle density at minimum, and a maximum, particle size 
 Log ash particle size for ash particle density at minimum, and at maximum, particle size 
 Eruptive power, eruption duration, and initial rise velocity of plume. 
Once entrained and erupted, atmospheric transport of ash and radionuclides is modeled directly 
in TSPA-LA using the software code ASHPLUME V 2.0 as identified and discussed in Section 8 
of BSC 2003 ([DIRS 161840]). Section 6.5.1 and 6.5.2 of BSC 2003 ([DIRS 161840]) describes 
the mathematical model and parameter inputs respectively, used to calculate ash-and-waste 
dispersal in the wind. The TSPA-LA model stochastically samples the number of waste 
packages hit and the parameters used as input in each single ASHPLUME .dll realization. The 
ASHPLUME model is executed from within the TSPA-LA GoldSim model, and ASHPLUME 
results are produced therein. Consequently, the processes defined by the ASHPLUME 
mathematical model are considered as explicitly included in the TSPA-LA. 
Related FEPs: 
FEPs that examine related but distinct effects and consequences: 
Igneous intrusion into repository (1.2.04.03.0A) 
Magma or pyroclastic base surge transports waste (1.2.04.05.0A) 
FEPs that examine similar effects and consequences: 
Igneous intrusion interacts with EBS components (1.2.04.04.0A) 
Ashfall (1.2.04.07.0A) 
Related Documents: 
Supplemental Discussion: None 
ANL-WIS-MD-000005 REV 01 
Characterize Eruptive Processes at Yucca Mountain, Nevada 
ANL-MGR-GS-000002 (BSC 2003 [DIRS 161838]) 
Number of Waste Packages Hit by Igneous Intrusion 
ANL-MGR-GS-000003 (BSC 2003 [DIRS 161851]) 
Atmospheric Dispersal and Deposition of Tephra from a Potential 
Volcanic Eruption at Yucca Mountain, Nevada 
MDL-MGR-GS-000002 (BSC 2003 [DIRS 161840]) 
135 Features, Events and Processes: Disruptive Events 
FEP Description: 
6.2.2.6 Ashfall (1.2.04.07.0A) 
Finely-divided waste particles are carried up a volcanic vent and 
deposited at land surface from an ash cloud. 
Descriptor Phrases: Volume and mass of erupted waste and ash, Entrainment of waste 
in ash plume in atmosphere, Atmospheric transport of waste in ash 
plume, Deposition of waste and ash 
Screening Decision: Included (BSC 2003 Table 5 [DIRS 161838]; BSC 2003, Table 6 
[DIRS 161840]) 
The TSPA-LA approach for addressing igneous intrusion is TSPA Disposition: 
outlined in the document Total System Performance Assessment- 
License Application Method and Approach (BSC 2002, 
Section 8.1.2 [DIRS 160146]) and includes consideration of 
exposure from an ashfall event. 
Table 22 of Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
(BSC 2003 [DIRS 163769]) indicates that the annualized frequency of one or more eruptive 
centers with the repository footprint is 1.3 x 10-8 (see Assumption 5.1 of this analysis report, 
ANL-WIS-000005 REV. 01). This is based on the repository footprint presented in 
800-IED-EBS0-00402-000-00B and 800-IED-EBS0-00401-000-00C (BSC 2003 [DIRS 161727, 
DIRS 162289]). Additionally, the lateral extent of ashfall is sufficient to reach the location of 
the RMEI, so the FEP has been included. 
The two igneous events (with individual probabilities and consequences) being modeled by the 
TSPA-LA are: 1) an igneous intrusion groundwater transport modeling case featuring the ascent 
of a basaltic dike or dike system (i.e., a set or swarm of multiple dikes comprising a single 
intrusive event) to the repository level where it intersects drifts; and 2) a volcanic eruption 
modeling case featuring the development of a volcano within the repository footprint with one or 
more conduits that intersect waste packages. The potential consequence of the second event 
(volcanic eruption modeling case) is that waste packages entrained within a conduit may be 
breached, releasing radionuclides in an erupting ash plume where they can be dispersed 
downwind to the RMEI. Based on the current design, the location of the RMEI is approximately 
18 kilometers (km) south of the repository (10 CFR 63.312 and 10 CFR 63.302, 66 FR 55732 
[DIRS 156671]). The conceptual model for the eruptive process is discussed under FEP 
1.2.04.06.0A (Eruptive conduit to surface intersects repository). The following discussion is 
focused on the eruption of entrained waste as ash into the atmosphere and subsequent transport 
and deposition. 
The analysis report Characterize Eruptive Processes at Yucca Mountain, Nevada (BSC 2003, 
Section 6 [DIRS 161838]) provides the technical basis for inclusion of the FEP in the TSPA-LA. 
Properties of basaltic eruptions described in the analysis report are based on the observed 
characteristics of past basaltic eruptions in the YMR and other analogous eruptions. This 
analysis report includes the results of field investigations dealing with physical volcanology and 
ANL-WIS-MD-000005 REV 01 136 Features, Events and Processes: Disruptive Events 
with ash and tephra redistribution, and includes the conceptual models for eruptive processes and 
for ash and tephra redistribution. This information is used to develop parameter value 
distributions appropriate for analysis of the consequences of volcanic eruptions through a 
proposed repository at Yucca Mountain, Nevada. In particular, this report addresses the 
following aspects of the related FEP: 
 The duration of eruptions, their power output, and mass discharge rates 
 The bulk grain size produced by relevant explosive eruptions and grain shapes. 
The parameters developed in the eruptive processes analysis report (BSC 2003, Table 37 
[DIRS 161838]) related to this FEP include the following: 
 Eruptive power 
 Eruption duration for formation of an entire volcano 
 Duration of a single explosive phase constituting a violent strombolian eruptive phase 
 Eruption volume 
 Mean particle size erupted during violent strombolian phases 
 Standard deviation of particle size distribution for a given mean 
 Clast characteristics 
 Density of erupted particles 
 Tephra deposit density. 
The results of the analysis report do not directly feed to the TSPA-LA model. Rather, the results 
provide input for the ASHPLUME model run within the TSPA-LA. Because the outputs of the 
listed report are used either implicitly or explicitly in the TSPA-LA model, and the outputs of the 
ASHPLUME model are dependent on the underlying inputs documented in the model report, the 
underlying inputs and related FEPs are considered to be implicitly included in the TSPA-LA 
model. 
The output from the eruptive processes analysis report (BSC 2003, Table 37 [DIRS 161838]) is 
used in the model report Atmospheric Dispersal and Deposition of Tephra from a Potential 
Volcanic Eruption at Yucca Mountain, Nevada (BSC 2003, Table 8 [DIRS 161840]) as input for 
developing the following parameters: 
 Mean ash particle diameter 
 Mean ash particle diameter standard deviation for particle size distribution 
 Ash particle shape factor 
 Ash particle density at minimum, and a maximum, particle size 
 Log ash particle size for ash particle density at minimum, and at maximum, particle size 
 Eruptive power and eruption duration. 
Additionally, the following process parameters are developed within the ASHPLUME model 
report: 
 Column diffusion constant, which affects the distribution of particles within the ash 
column 
137 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
 Waste incorporation ratio, a mathematical construct used to transport a density-corrected 
combined ash and fuel particle 
 Waste particle size (min, max, mode) 
 Windspeed and wind direction, based on site-specific data collected over the appropriate 
range of ash column height 
 Initial rise velocity of plume 
 Eddy diffusivity constant, with the simplification made that particle diffusion time equals 
particle fall time). 
Once entrained and erupted, atmospheric transport of ash and radionuclides is modeled directly 
in TSPA-LA using the software code ASHPLUME V 2.0 as identified and discussed in Section 8 
of BSC 2003 ([DIRS 161840]). The TSPA-LA model, using ASHPLUME V 2.0, estimates 
radionuclide concentrations in contaminated ash falling at the location of the RMEI, 
approximately 18 km south of the repository. For the volcanic eruption modeling case, the 
TSPA-LA presumes that a hypothetical violent strombolian eruption occurs through a section of 
the repository, entraining radionuclide-bearing wastes in the ash plume that disperses downwind 
and deposits contaminated ash on the ground surface. Sections 6.5.1 and 6.5.2 of BSC 2003 
([DIRS 161840]) describes the mathematical model and parameter inputs, respectively, used to 
calculate ash-and-waste dispersal in the wind. The ASHPLUME model is executed from within 
the TSPA-LA GoldSim model, and ASHPLUME results are produced therein. The TSPA-LA 
model stochastically samples the number of waste packages hit and the parameters used as input 
in each single ASHPLUME realization. The ASHPLUME code specifically addresses the issues 
of waste incorporation into the volcanic ash, the extent of the ash plume into the atmosphere, the 
atmospheric transport of the ash and entrained waste, and the thickness of ash deposits in the 
vicinity of the RMEI. These aspects of the FEP are, therefore, considered explicitly included in 
the TSPA-LA model. 
Related FEPs 
FEPs that examine related but distinct effects and consequences: 
Igneous intrusion into repository (1.2.04.03.0A) 
Igneous intrusion interacts with EBS components (1.2.04.04.0A) 
Magma or pyroclastic base surge transports waste (1.2.04.05.0A) 
Ash redistribution via soil and sediment transport (1.2.04.07.0C) 
FEPs that examine similar effects and consequences: 
Eruptive conduit to surface intersects repository (1.2.04.06.0A) 
Characterize Eruptive Processes at Yucca Mountain, Nevada Related Documents: 
ANL-MGR-GS-000002 (BSC 2003 [DIRS 161838]) 
138 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Supplemental Discussion: None 
6.2.2.7 Ash Redistribution via Soil and Sediment Transport (1.2.04.07.0C) 
FEP Description: 
Descriptor Phrases: 
Screening Decision: 
Screening Argument: 
TSPA Disposition: 
Table 22 of Characterize Framework for Igneous Activity at Yucca Mountain, Nevada (BSC 
2003 [DIRS 163769]) indicates that the annualized frequency of one or more eruptive centers 
with the repository footprint is 1.3 x 10-8 (see Assumption 5.1 of this analysis report, 
ANL-WIS-MD-000005 REV. 01). This is based on the repository footprint presented in 
800-IED-EBS0-00402-000-00B and 800-IED-EBS0-00401-000-00C (BSC 2003 [DIRS 161727, 
DIRS 162289]). Additionally, the lateral extent of ashfall from such an event, and subsequent 
ash redistribution, is sufficient to reach the location of the RMEI, so the FEP has been included. 
For the volcanic eruption modeling case, the TSPA-LA presumes that a hypothetical violent 
strombolian eruption occurs through a section of the repository, entraining radionuclide-bearing 
wastes in the ash plume that disperses downwind and deposits contaminated ash on the ground 
surface. The TSPA-LA model, using ASHPLUME V 2.0, estimates radionuclide concentrations 
in contaminated ash falling at the location of the RMEI, approximately 18 km south of the 
repository (10 CFR 63.312 and 10 CFR 63.302, 66 FR 55732 [DIRS 156671]). The TSPA-LA 
approach for calculating exposure through the use of volcanic-specific biosphere dose 
conversion factors is further outlined in the document Total System Performance 
Assessment-License Application Method and Approach (BSC 2002, Section 8.1.2 
[DIRS 160146]). 
This hypothetical direct deposition of ash and waste in the vicinity of the RMEI presumably 
represents the greatest degree of exposure from an eruptive process. All other mechanisms 
(e.g., eolian or fluvial processes) allow for mixing and dilution of the ash and waste through 
distance and with time. Presumably, a volume of transported sediment with a highly diluted ash 
component would have less impact on the RMEI than would primary ashfall that fell directly on, 
ANL-WIS-MD-000005 REV 01 
Following deposition of contaminated ash on the surface, ash 
deposits may be redistributed on the surface via aeolian and fluvial 
processes. 
Redistribution of contaminated ash (surficial) 
Included (BSC 2003 Table 5 [DIRS 161838]) 
Not Applicable 
Ashfall events and processes are directly addressed in Atmospheric 
Dispersal and Deposition of Tephra from a Potential Volcanic 
Eruption at Yucca Mountain, Nevada (BSC 2003 [DIRS 161840]). 
The TSPA-LA includes consideration of exposure from 
redistributed ash. 
139 
Atmospheric Dispersal and Deposition of Tephra from a Potential 
Volcanic Eruption at Yucca Mountain, Nevada 
MDL-MGR-GS-000002 (BSC 2003 [DIRS 161840]) Features, Events and Processes: Disruptive Events 
or nearby, the RMEI. Accordingly, the worst-case conceptual model would be one in which 
winds blow the initial eruption column south from the repository toward the RMEI. This is the 
only conceptual model in which ash would directly fall on the RMEI without additional dilution. 
Regardless, the effects of ash redistribution via soil and sediment transport will be explicitly 
included in the TSPA-LA Model in conjunction with an ashfall event. A model abstraction will 
be run, developed, and executed as part of the TSPA-LA model. 
To assess the degree to which redistribution and mixing processes (primarily fluvial processes) 
might affect the percent of ash/waste in reworked and transported sediment and its contribution 
to exposure, a study was performed using the ash deposits and tephra sheet of the Lathrop Wells 
cone and cesium-137 studies in the Fortymile Wash alluvial fan. The results of these studies are 
documented in Characterize Eruptive Processes at Yucca Mountain, Nevada (BSC 2003, Section 
6.5 [DIRS 161838]) and Atmospheric Dispersal and Deposition of Tephra from a Potential 
Volcanic Eruption at Yucca Mountain, Nevada (BSC 2003 [DIRS 161840]). Both reports 
include the results of field investigations and present the conceptual and technical basis for the 
ash redistribution model implemented within TSPA-LA. The technical basis for the TSPA ash 
redistribution model is supported by geomorphic data and analyses, including: 
 The rate of erosion/deposition of sediments on the Fortymile Wash alluvial fan 
 Ash dilution rate 
 Site erosion/aggradation rate. 
Conceptually, the region surrounding the RMEI is an alluvial fan and can be divided into two 
major geomorphic units: interchannel divides and the channels themselves. Within the 
channels, sediment transport processes will move contaminated ash through the region in 
response to storm events, effectively creating a permanent layer of contamination following an 
eruption. Eventually, the watershed will be depleted of contaminated ash, but the duration for 
this process is unknown and, therefore, the effect is assumed to remain constant. Mixing 
processes will dilute the ash with uncontaminated sediment, but existing data are insufficient to 
quantify that dilution. The conceptual basis, therefore, is to assume that the sediment in the 
channels has the initial concentration of radionuclides in the ashfall at the RMEI location. The 
concentration at the RMEI location represents a concentration undiluted by additional transport 
mechanisms. 
Because of the topographic setting and hydraulic characteristics, alluvial fans are typified by 
coarse gravel in proximal reaches and a rapidly decreasing grain size downfan. Within this 
larger setting, local concentrations of placer minerals will occur, and may include denser and/or 
larger waste fragments. However, waste particles subject to differential settling, although more 
likely to result in localized concentrations, are less likely to be transported distances on the order 
of kilometers necessary to impact the RMEI. Consequently, not accounting for this differential 
settling is reasonable because the RMEI dose will come from exposures averaged over an area 
that is larger than individual placer deposits, and using a regional average concentration is 
therefore appropriate. 
The cesium data (BSC 2003, Section 6.5.2.5 [161838]) suggest that there has been significant net 
erosion in the last 50 years (1-3 cm). Conceptually, it is assumed that any future ashfall deposits 
in the interchannel divide areas will be removed at least at that rate over the long term (although 
140 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
it is recognized that in the short term, the rate may be greater on the slopes of Yucaa Mountain, 
for unconsolidated material, and during major flood events). That rate (13 cm per 50 years) 
results in a zero layer thickness relatively quickly in the interchannel divide areas. However, in 
the interchannel divide areas, cesium data indicates that some cesium has leached into the lower 
soil horizons (down to 9 cm). The conceptual basis, therefore, is to assume a lower bound 
concentration fixed at 1/100th of the initial concentration. This assumption is consistent with the 
cesium data for the lower soil horizons in that it restricts the radionuclide concentration in the 
interdivide areas from reaching zero, even though the ash is gone. This also accounts for 
radionuclides that may be brought up onto the divides during the rare major flood events that 
inundate the entire fan. 
Related FEPs 
FEPs that examine related but distinct effects and consequences: 
Magma or pyroclastic base surge transports waste (1.2.04.05.0A) 
Eruptive conduit to surface intersects repository (1.2.04.06.0A) 
Ashfall (1.2.04.07.0A) 
Ash redistribution via groundwater (1.2.04.07.0B) 
Hydrologic response to igneous activity (1.2.10.02.0A) 
FEPs that examine similar effects and consequences: 
Erosion/denudation (1.2.07.01.0A) 
Deposition (1.2.07.02.0A) 
Topography and morphology (2.3.01.00.0A) 
Soil and sediment transport in the biosphere (2.3.02.03.0A) 
Related Documents: 
Descriptor Phrases: 
6.2.2.8 Hydrologic Response to Igneous Activity (1.2.10.02.0A) 
FEP Description: 
ANL-WIS-MD-000005 REV 01 
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. 
Water table elevation, Saturated flow and pathways in the SZ, 
Unsaturated flow and pathways in the UZ 
141 
Characterize Eruptive Processes at Yucca Mountain, Nevada 
ANL-MGR-GS-000002 (BSC 2003 [DIRS 161838]) 
Atmospheric Dispersal and Deposition of Tephra from a Potential 
Volcanic Eruption at Yucca Mountain, Nevada 
MDL-MGR-GS-000002 (BSC 2003 [DIRS 161840]) Features, Events and Processes: Disruptive Events 
[Note: This is a shared FEP. The scope and intent of this analysis 
report is to quantify the amplitude of the event to be considered. 
The full technical basis for these shared FEPs is addressed 
collectively by all of the sharing FEP AMRs. Descriptor phrases 
not addressed or only partially addressed in this report are further 
addressed in the sharing FEP AMRs.] 
ExcludedLow Consequence Screening Decision: 
Screening Argument: Igneous intrusion into the repository (i.e., igneous activity) could 
potentially alter the hydrologic characteristics of the site and, 
thereby, affect flow-and-transport characteristics and release to the 
accessible environment and exposure. However, the orientation of 
the dikes and the limited scale of a few meters indicate that the 
hydrologic response would be of low consequence. 
An appropriate analog for understanding the characteristics of a volcanic event at Yucca 
Mountain is the Paiute Ridge intrusive/extrusive center (Byers and Barnes 1967 [DIRS 101859]) 
on the northeastern margin of the Nevada Test Site. Paiute Ridge is a small-volume Miocene 
volcanic center comparable in volume and composition to Quaternary volcanoes near Yucca 
Mountain (CRWMS M&O 1998, p. 5-29 [DIRS 105347]). Paleomagnetic, geochronologic, and 
geochemical data indicate that the entire intrusive/extrusive complex formed during a brief 
magmatic pulse and, thus, represents a single volcanic event (Ratcliff et al. 1994 [DIRS 106634]; 
and CRWMS M&O 1998, p. 5-29 [DIRS 105347]). The vents and associated dike system 
formed within a north-northwest-trending extensional graben. This analog site provides 
excellent exposures of a variety of depths of the system, including remnants of surface lava 
flows, volcanic conduits, and dikes and sills intruded into tuff country rock at depths of up to 
300 meters (CRWMS M&O 1998, pp. 5-27 through 5-41 [DIRS 105347]). There is evidence of 
shallow structural control of dike emplacement at Paiute Ridge, including dike emplacement 
along fault planes (Byers and Barnes 1967 [DIRS 101859]; and CRWMS M&O 1998, pp. 5-27 
and 5-28, [DIRS 105347]). Dike lengths at Paiute Ridge range from <1 km to 5 km (CRWMS 
M&O 1998, p. 5-31 [DIRS 105347]), comparable to the range estimated for post-Miocene 
volcanism near Yucca Mountain. 
Carter-Krogh and Valentine (1996, pp. 7 and 8 [DIRS 160928] referenced in 
DTN: MO0310INPDEFEP.000 [DIRS 165880]) described the margins of the Paiute Ridge dike 
complex as follows: 
PR dike contains ubiquitous near-vertical joints that result in a pervasive platy 
texture with plates parallel to the dike-host contact. Conversely, with the 
exception of local cooling joints in fused wall rock (extending 10 cm to 20 cm 
into the wall rock, perpendicular to the dike margin), joints are never visible in the 
host rock along the length of the dike. The contact between basalt and the tuff 
host rock is consistently smooth and shows no brecciation. Along strike at this 
contact, the tuff host rock is fused or welded to varying degrees: in places the tuff 
is completely welded and forms black vitrophyre that grades rapidly away from 
the contact, over a distance of ca 20 cm to 100 cm, into nonwelded tuff that is 
142 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
apparently unaffected by the dike. In other places the tuff is only partly welded at 
the contact and black fiamme are elongated parallel to the contact. We infer that 
this contact welding is the combined result of heat from the dike and 
compressive stress exerted by the flowing magma on the wall rocks. Welded host 
rock commonly contains vesicles that are elongated vertically and parallel to the 
margin. In some places, welded tuff coats the basalt and displays rills or elongate 
smooth ridges (flutes). Most rills plunge nearly vertically, however, a subhorizontal 
rill is present in the central part of the dike. At the dike tip, exposed at 
Slanted Buttes, scoria patches crop out near the dike-host contact. 
The two eastern dikes, M and E  show geometries and textures similar to those 
of PR; however, M dike is much shorter and does not feed a sill, and E dike was 
emplaced closest to the paleosurface and feeds two sills. M dike  visibly 
occupies a normal fault, oriented N40 W, 61 E,  Its host rocks are only 
Tertiary tuffs, which show no brecciation or jointing near the dike contact  
Texture within the dike is characterized by a vertical platy fabric that parallels the 
dike margins. E dike is the eastern-most dike studied within the graben.  Near 
the neck, the dike visibly occupies a NNW-trending, steeply E-dipping normal 
fault that displaces bedded tuffs 3.5 m and does not cut the dike The texture of 
E dike is characterized by the pervasive vertical platy fabric common to M and 
PR dikes. Adjacent host tuffs are not jointed nor brecciated, except for local 
vertical jointing of the Rainier Mesa tuff, which is intruded by the dike at its 
shallowest level. The contact of the dike and host tuff is preserved in places and 
varies from partly to completely welded in the same manner as described above 
for the PR dike. Where complete welding has occurred, vesicles are vertical and 
parallel the dike margin. Contact welding of the host tuffs formed oblate fiamme 
that parallel the dike-host contact. Visible thermal effects on the wall rocks 
disappear within one meter of the dike margin. 
This suggests that zones of change in rock properties (i.e., formation of vitrophyres and/or 
various degrees of welding of the host rock) are limited to between a few tens of centimeters to 
at most a meter perpendicular to the dike. Other features such as the platy texture along the dike 
margins and vesicles in the welded tuff are oriented parallel to the dike margins. This suggests 
that the primary direction of increased or decreased permeability (if any) is parallel with the dike 
margins. The description also indicates the interaction of faults and dikes and alludes to the 
segmented, discontinuous, en echelon structures observed for the dike complex. 
Most researchers conclude that once dikes feeding volcanoes enter the shallow upper crust, their 
location and orientation are influenced by the orientation of the local stress field and the presence 
of faults that may locally control vent location and alignment. The evidence cited for these two 
conclusions includes several northeast-oriented vent alignments in the YMR and the association 
of eruptive centers with known or inferred faults (Smith et al. 1990 p. 83 [DIRS 101019]; 
CRWMS M&O 1996 Appendix E, [DIRS 100116] p. AM-4; Connor et al. 1996, p. 78 
[DIRS 135969]; Reamer 1999, Section 4.1.3.3.3 [DIRS 119693]). 
The results of the PVHA are summarized in the analysis report Characterize Framework for Igneous 
Activity at Yucca Mountain, Nevada (BSC 2003 [DIRS 163769]), and the analysis report presents 
143 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
probability distributions for the length and orientation of volcanic dikes within the repository 
footprint. The individual PVHA expert dike length distributions can be aggregated to derive a 
PHVA aggregate dike length distribution. The aggregate dike-length distribution derived from 
the PVHA has 5th-percentile, mean, and 95th-percentile values of 0.6, 4.0, and 10.1 km, 
respectively and the most commonly assigned dike orientation centers on N30E (BSC 2003, 
Section 6.3.2 [DIRS 163769]). The analysis, based on the results of the PVHA, also assigns the 
highest probabilities of dike orientation to azimuths of between 20 and 40 degrees (BSC 2003, 
Table 18 [DIRS 163769]). 
The anisotropic transmissivity in the SZ observed in the Yucca Mountain region has a maximum 
principal transmissivity direction of approximately N15E (BSC 2003, Section 6.5.2.10 
[DIRS 164870]), which is consistent with the fault and fracture orientation, and a corroborative 
analysis by Ferrill et al. (1999, p. 1 [DIRS 118941]), which indicates N30E. Based on the PVHA 
results, future dikes also most likely will trend in a north-to-northeast direction, although this 
may be altered by the presence of existing faults, or localized changes in the stress field with the 
orientation being perpendicular to the least compressive stress. A north-to-northeast trend 
parallels or sub-parallels the faults and fractures active in the present-day in situ stress field. 
Dike features, such as the platy texture and welded surfaces that could affect the permeability, 
will presumably parallel the dike orientation and be aligned in a north-to-northeast orientation. 
This parallel to subparallel orientation of dikes and maximum principal transmissivity, coupled 
with the expected limited affected volume of material around the dikes, indicates that dikes, even 
if differing in permeability, will not significantly affect groundwater flow patterns at the 
mountain scale. By way of corroboration, an early analysis of the effect of a dike on flow in the 
SZ was conducted and documented in Chapter 10 of the TSPA for the Viability Assessment 
(CRWMS M&O 1998, Section 10.4.4 [DIRS 100369]). The corroborative analysis suggested 
that there would be negligible impact for a dike oriented north-to northeast. The analysis 
included a variety of dike lengths and locations respective to the repository area. Additionally, 
the occurrence of such a change is conditional on a low probability event of an igneous intrusion. 
CRWMS M&O (1998, p. 5-56 [DIRS 105347]) mentions the possibility of perched water 
forming near low-permeability intrusive bodies, and there is concern regarding the potential for a 
dike to provide a barrier to flow and/or cause impoundments. Because of the parallel to 
subparallel orientation of dikes with the existing orientation of the anisotropic maximum 
horizontal permeability in the SZ, a dike would not form a barrier or impoundment that would 
have any significant effect on flow in the SZ. In the UZ, the primary direction of groundwater 
flow is vertically through the fractures, although some horizontal flow component exists in the 
matrix. Because the joints on a dike margin would be near vertical, it would seem that the 
formation of a significant perched water zone is problematic without the formation of a sill. The 
potential for formation of a sill is addressed in the FEP 1.2.04.03.0A (Igneous intrusion into 
repository). The formation of a perched water zone is addressed in the FEP 2.2.07.07.0A 
(Perched water develops) and has been included in the TSPA-LA. Even if a perched water zone 
were to form and then drain, there would be only a minimal impact, as explained in the FEP 
2.2.06.03.0A (Seismic activity alters perched water zone). 
With regard to geochemical changes and based on the study of natural-analogue sites, CRWMS 
M&O (1998, p. 5-1 and 5-2 [DIRS 105347] referenced in DTN: MO0310INPDEFEP.000 
144 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
[DIRS 165880]) mentions that, for shallow, small-volume basaltic intrusions, the chemical and 
mineralogical studies of host tuffs indicate that alteration is limited to within a few tens of meters 
of the intrusion. More particularly, from a study of the Paiute Ridge analogue site, there is no 
indication for extensive hydrothermal circulation and alteration, brecciation and deformation 
related to magmatic intrusion, and vapor-phase recrystallization during the magmatic intrusions 
into the vitric and zeolitized tuffs (CRWMS M&O 1998, p. 5-42 [DIRS 105347] referenced in 
DTN: MO0310INPDEFEP.000 [DIRS 165880]). The analogue studies show that alteration is 
quite limited, typically only found within 5 to 10 m of intrusions (CRWMS M&O) 1998, p. 5-41 
[DIRS 105347] referenced in DTN: MO0310INPDEFEP.000 [DIRS 165880]). At the Paiute 
Ridge site, low-temperature secondary minerals persist near the contact with intrusions 
(CRWMS M&O 1998, p. 5-46 [DIRS 105347]). This suggests that little destruction of sorptive 
minerals is expected. Given the limited area of alteration and the consequent change of rock 
properties around the intrusion, the effect of alteration is minimal, and alteration does not 
provide a mechanism to significantly change the dose. Therefore, this FEP is Excluded from the 
TSPA-LA based on low consequence. 
CRWMS M&O (1998, p. 5-86 [DIRS 105347]) also considered the effects of hydrothermal 
systems (the heating up of groundwater and rock) resulting from igneous intrusions. Findings 
from the Paiute Ridge analogue site indicate that the occurrence of clinoptilolite and opal also 
suggests that thermal transfer into the adjacent country rock was minimal (CRWMS M&O 
1998, p. 5-57 [DIRS 105347] referenced in DTN: MO0310INPDEFEP.000 [DIRS 165880]). 
Findings from the Grants Ridge site suggest the absence of a hydrothermal system, except for 
localized recrystallization of volcanic glass within the contact zone (CRWMS M&O 1998, p. 5-74 
[DIRS 105347]). Further, the study concluded that an intrusion at Yucca Mountain would 
not result in large amounts of hydrothermally driven mass transfer (CRWMS M&O 1998, 
p. 5-74 [DIRS 105347]). 
With regard to post-intrusion in-drift conditions, the TSPA-LA addresses conditions through an 
assumption (see BSC 2003, Section 5.1.3 [DIRS 165002] for justification) that the permeability 
of any contact metamorphic aureole surrounding the intruded drifts is as great as that of the bulk 
host rock. The basalt is assumed to fracture during cooling so that it too provides no barrier to 
flow. After post-intrusive magma cooling and reversion to normal in-drift environmental 
conditions, the seepage water is expected to flow through the contact metamorphic aureole and 
react first with the basalt in the intruded emplacement drifts, resulting in basalt-equilibrated 
seepage water. The geochemical interaction of seepage water with the basalt and the resulting 
hydrochemistry are simulated using EQ6 model, all as described in BSC 2003 (Section 6.5.3 
[DIRS 165002]). 
By way of corroborative information, for a dike initially intruding into the SZ, Rojstaczer 
(1991 [DIRS 163416]) indicates a rise in the water table of a few tens of meters. Also of a 
corroborative nature and based on their initial stage work with highly simplified systems used to 
represent Yucca Mountain, Valentine and others (CRWMS M&O 1998, p. 5-86 [DIRS 105347]) 
suggest that the horizontal distance over which an intrusion affects convective air flow is always 
less than 2.5 km, and that the dike or sill particles representing magmatic volatiles never travel 
more than approximately 500 meters horizontally. Consequently, the development of 
hydrothermal systems from igneous activity is Excluded from the TSPA-LA based on low 
consequence due to their limited size respective to the repository footprint. 
145 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
The potential for igneous activity (primarily via eruption or effusive flow) to change surface 
topography, and subsequently affect drainage and infiltration is possible, albeit at the same or 
slightly lower probability than for an eruptive event. The net effect could, hypothetically, result 
in temporary damming of a drainage intersected by a dike at the surface, or from the sluffing of 
ash materials from hill slopes. While possible, the steep topographic gradients at Yucca 
Mountain above the repository, the increased sedimentation rate associated with ash 
redistribution in comparison to unaffected areas as discussed for FEP 1.2.04.07.0C (Ash 
redistribution via soil and sediment transport), and the limited extent of effusive flow from 
small-scale volcanoes such as Lathrop Wells, would tend to limit the consequences of any such 
topographic changes. The net result through time would likely resemble something akin to 
Lathrop Wells cone, wherein drainage patterns readjust and re-equilibrate to match the change in 
conditions, resulting in relocation of the drainage rather than any significant ponding or 
increased infiltration effects. 
Furthermore, in 10 CFR 63.305(b and c) (66 FR 55732 [DIRS 156671]), the NRC states that: 
b) 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 the 
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. 
c) DOE must 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 definition of reference biosphere at 10 CFR 63.2 (66 FR 55732 [DIRS 156671]) specifically 
identifies topography as being a component of the reference biosphere. 
Reference biosphere means the description of the environment inhabited by 
the reasonably maximally exposed individual. The reference biosphere 
comprises the set of specific biotic and abiotic characteristics of the 
environment, including, but not necessarily limited to, climate, topography, 
soils, flora, fauna, and human activities. 
By NRCs juxtaposition of varying geologic and hydrologic factors with the required 
characteristics of the reference biosphere, it is inferred that the listed regulatory constraint of 
changes in the reference biosphere may also be applicable to conditions at Yucca Mountain. In 
particular, it is inferred that changes in the biosphere (other than climate), which result from 
geologic disruptive events, should not be projected. Specifically identified in the definition of 
the referenced biosphere are changes to soil, topography, and flora. By inference, an allowable 
interpretation is that DOE should not project changes in the topography and soils properties and 
must assume that the topography and soils remains constant. 
Whether the damming of drainages by ash or effusive magma flow is a geologic or topographic 
change is subject to discussion. For purposes of this analysis report, it is classified as a 
topographic change in that topography is defined as the physical features of a district or region, 
146 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
such as are represented on maps, taken collectively; especially, the relief and contour of the land 
(Bates and Jackson 1984 [DIRS 128109]). The mechanisms for damming of the streams stem 
from a change in relief or contour, although in this case the triggering mechanism for the change 
is a geologic event. 
Similarly, the change in infiltration rates to a change in soils stemming from a geologic event 
also appears to be precluded by the regulations. Regardless, from USGS 2001 (Section 6.1.2 
[DIRS 1620355]) and from Flint and Flint (1995 [DIRS 100394] referenced in 
DTN: MO0310INPDEFEP.000 [DIRS 165880]), the USGS states that the soils exceeding 
6 meters in thickness eliminate the infiltration of water to the soil/bedrock contact except in 
channels. This implies that the unconsolidated surficial deposits will trap infiltrating water, but 
rather than shielding this water from evapotranspiration, it will allow evapotranspiration to 
remove the water that otherwise would escape the zone of evapotranspiration through infiltration 
directly into rock fractures. Furthermore, significant reduction of volume of basaltic ash per 
volume of sediment has been observed to occur over short distances at the Lathrop Well Cone 
(BSC 2003, Section 6.5.1.4 [DIRS 161838]), suggesting that such affects would be extremely 
localized. 
A more restrictive and alternative interpretation would strictly limit the constraints to the 
reference biosphere (i.e., that area inhabited by the RMEI and/or that outside of the controlled 
area) located 18 km south of the repository and not to the repository area. Alternatively, the 
changes in topography and soil could, hypothetically, be classified as hydrologic changes rather 
than geologic or topographic, because the changes affect surface drainages and infiltration. Or, 
the juxtaposition of the regulations could be inferred to mean that the static condition of the 
biosphere characteristics apply to the nominal case, but not the disruptive case. 
Regardless of the regulatory interpretation, the technical basis of the argument is sufficient to 
presume low consequence of the resulting changes in topography and soils and Yucca Mountain 
that result from an eruptive event. 
In summary, the parallel orientation of dikes and the direction of maximum transmissivity, 
coupled with the expected, limited affected-volume of the SZ and the generally low probability 
of an igneous intrusion, indicates that dikes, even if differing in permeability from the host rock, 
will not significantly affect groundwater-flow patterns or water levels. Because there would be 
no significant change to the flow system, hydrologic response to igneous activity does not 
provide a mechanism for significantly changing dose. Given the limited area of alteration and 
the consequent change of rock properties around the intrusion, the effect of alteration would be 
minimal, and alteration would not provide a mechanism to significantly change the dose. 
Furthermore, the development of hydrothermal systems from igneous activity is Excluded from 
the TSPA-LA based on low consequence due to their limited size and minimal rise in the water 
table respective to the repository footprint. Consequently, Hydrologic response to igneous 
activity is Excluded from the TSPA-LA based on low consequence. 
TSPA Disposition: Not Applicable 
147 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Related FEPs: 
FEPs that examine related but distinct effects and consequences 
Tectonic activitylarge scale (1.2.01.01.0A) 
Igneous intrusion into repository (1.2.04.03.0A) 
Magma or pyroclastic base surge transports waste (1.2.04.05.0A) 
Ash redistribution via soil and sediment transport (1.2.04.07.0C) 
Erosion/denudation (1.2.07.01.0A) 
Deposition (1.2.07.02.0A) 
Diapirism (1.2.09.01.0A) 
Hydrologic response to seismic activity (1.2.10.01.0A) 
Water table decline (1.3.07.01.0A) 
Water table rise (1.3.07.02.0A) 
Rind (chemically altered zone) forms in the near field (2.1.09.12.0A) 
Rock properties of host rock and other units (2.2.03.02.0A) 
Perched water develops (2.2.07.07.0A) 
Geochemical interactions and evolution in the SZ (2.2.08.03.0A) 
Geochemical interactions and evolution in the UZ (2.2.08.03.0B) 
Topography and Morphology (2.3.01.00.0A) 
FEPs that examine similar effects and consequences 
Hydrothermal activity (1.2.06.00.0A) 
Thermally-induced stress changes in the near field (2.2.01.02.0A) 
Thermomechanical stresses alter characteristics of fractures near repository 
(2.2.10.04.0A) 
Thermomechanical stresses alter characteristics of faults near repository 
(2.2.10.04.0B) 
Thermomechanical stresses alter characteristics of rocks above and below the 
repository (2.2.10.05.0A) 
Related Documents: None 
Supplemental Discussion: None 
ANL-WIS-MD-000005 REV 01 148 Features, Events and Processes: Disruptive Events 
Table 7.1 provides a summary of the DE FEP-screening decisions and the basis for the decisions. 
This analysis report may be affected by technical product input information that requires 
confirmation. Any changes to the document that are required because of completing the 
confirmation activities will be reflected in subsequent revisions. The quality status of the 
technical product input may be confirmed by review of the database. 
TSPA-LA 
FEP Number 
1.2.01.01.0A 
1.2.03.02.0A 
1.2.03.02.0C 
1.2.03.02.0D 
1.2.03.03.0A Seismicity associated with igneous activity 
1.2.10.01.0A 
2.2.06.01.0A 
2.2.06.02.0A 
2.2.06.02.0B 
2.2.06.03.0A 
1.2.04.02.0A 
1.2.04.03.0A 
1.2.04.04.0A 
1.2.04.05.0A 
1.2.04.06.0A 
1.2.04.07.0C 
1.2.10.02.0A 
Section Where 
Addressed 
6.2.1.1 
6.2.1.2 
6.2.1.3 
6.2.1.4 
6.2.1.5 
Included 6.2.1.6 
6.2.1.7 
6.2.1.8 
6.2.1.9 
6.2.1.10 
6.2.1.11 
6.2.1.12 
6.2.2.1 
6.2.2.2 
6.2.2.3 
6.2.2.4 
6.2.2.5 
1.2.04.07.0A Ashfall Included 6.2.2.6 
6.2.2.7 
6.2.2.8 
Screening Decision 
and Basis 
Excluded 
Low Consequence 
1.2.02.03.0A Fault displacement damages EBS components Included 
Seismic ground motion damages EBS components Included 
1.2.03.02.0B Seismic-induced rockfall damages EBS components Included 
Excluded 
Low Consequence 
Included 
Excluded 
Low Consequence 
Excluded 
Low Consequence 
Excluded 
Low Consequence 
Excluded 
Low Consequence 
Excluded 
Low Consequence 
Excluded 
Low Consequence 
Included 
Included 
Excluded 
Low Consequence 
Included 
Included 
Excluded 
Low Consequence 
Table 7-1. Summary of DE FEP Screening Decisions. 
TSPA-LA FEP Name 
Seismic-related FEPs 
Tectonic activitylarge scale 
Seismic-induced drift collapse damages EBS 
components 
Seismic-induced drift collapse alters in-drift 
thermohydrology 
Hydrologic response to seismic activity 
Seismic activity changes porosity and permeability 
of rock 
Seismic activity changes porosity and permeability 
of faults 
Seismic activity changes porosity and permeability 
of fractures 
Seismic activity alters perched water zones 
Igneous-related FEPs 
Igneous activity changes rock properties 
Igneous intrusion into repository 
Igneous intrusion interacts with EBS components 
Magma or pyroclastic base surge transports waste 
Eruptive conduit to surface intersects repository 
Ash redistribution via soil and sediment transport 
Hydrologic response to igneous activity 
7. CONCLUSIONS 
ANL-WIS-MD-000005 REV 01 149 Features, Events and Processes: Disruptive Events 
8. INPUTS AND REFERENCES 
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Scientific Laboratory. ACC: HQS.19880517.1541. 
158 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
103485 Wernicke, B.; Davis, J.L.; Bennett, R.A.; Elosegui, P.; Abolins, M.J.; Brady, R.J.; 
House, M.A.; Niemi, N.A.; and Snow, J.K. 1998. Anomalous Strain Accumulation 
in the Yucca Mountain Area, Nevada. Science, 279, 2096-2100. New York, New 
York: American Association for the Advancement of Science. TIC: 235956. 
100188 Whitney, J.W., ed. 1996. Seismotectonic Framework and Characterization of 
Faulting at Yucca Mountain, Nevada. Milestone 3GSH100M. Denver, Colorado: 
U.S. Geological Survey. ACC: MOL.19970129.0041; through; 
MOL.19970129.0062. 
161728 Williams, N.H. 2001. Contract No. DE-AC08-01RW12101 - KTI Deliverable to 
NRC - October 2001. Letter from N.H. Williams (BSC) to S.J. Brocoum 
(DOE/YMSCO), October 16, 2001, 1012010135, LTS:cdg, with enclosures. 
ACC: MOL.20020206.0018. 
155426 Wilson, S.F. and Cline, J.S. 2001. Paragenesis, Temperature and Timing of 
Secondary Minerals at Yucca Mountain. Back to the Future - Managing the Back 
End of the Nuclear Fuel Cycle to Create a More Secure Energy Future, Proceedings 
of the 9th International High-Level Radioactive Waste Management Conference 
(IHLRWM), Las Vegas, Nevada, April 29-May 3, 2001. La Grange Park, Illinois: 
American Nuclear Society. TIC: 247873. 
105544 Wohletz, K. and Heiken, G. 1992. Volcanology and Geothermal Energy. Berkeley, 
California: University of California Press. TIC: 241603. 
140956 Wohletz, K.H. 1986. Explosive Magma-Water Interactions: Thermodynamics, 
Explosion Mechanisms, and Field Studies. Bulletin of Volcanology, 48, 245-264. 
Berlin, Germany: Springer-Verlag. TIC: 225183. 
163662 Woods, A.W.; Sparks, S.; Bokhove, O.; LeJeune, A-M.; Conner, C.B.; and Hill, B.E. 
2002. Modeling Magma-Drift Interaction at the Proposed High-Level Radioactive 
Waste Repository at Yucca Mountain, Nevada, USA. Geophysical Research 
Letters, 29, (13), 19-1 through 19-4. [Washington, D.C.]: American Geophysical 
Union. TIC: 254467. 
8.2 CODES, STANDARDS, REGULATIONS, AND PROCEDURES 
155216 66 FR 32074. 40 CFR Part 197, Public Health and Environmental Radiation 
Protection Standards for Yucca Mountain, NV; Final Rule. Readily available. 
156671 66 FR 55732. Disposal of High-Level Radioactive Wastes in a Proposed Geologic 
Repository at Yucca Mountain, NV. Final Rule 10 CFR Part 63. Readily available. 
162317 67 FR 62628. Specification of a Probability for Unlikely Features, Events and 
Processes. Readily available. 
159 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
164786 AP-2.22Q, Rev. 1, ICN 0. Classification Analyses and Maintenance of the Q-List. 
Washington, D.C.: U.S. Department of Energy, Office of Civilian Radioactive Waste 
Management. ACC: DOC.20030807.0002. 
164073 AP-3.15Q, Rev. 4, ICN 2. Managing Technical Product Inputs. Washington, D.C.: 
U.S. Department of Energy, Office of Civilian Radioactive Waste Management. 
ACC: DOC.20030627.0002. 
165023 AP-SI.1Q, Rev. 5, ICN 2. Software Management. Washington, D.C.: U.S. 
Department of Energy, Office of Civilian Radioactive Waste Management. ACC: 
DOC.20030902.0003. 
164456 AP-SIII.9Q, Rev. 1, ICN 1. Scientific Analyses. Washington, D.C.: U.S. Department 
of Energy, Office of Civilian Radioactive Waste Management. ACC: 
DOC.20030929.0005. 
8.3 SOURCE DATA 
152643 MO0002SPATOP00.001 Topographic Grid Data. Submittal date: 02/24/2000. 
149092 MO0004MWDRIFM3.002. Results of the Yucca Mountain Probabilistic Seismic 
Hazard Analysis (PSHA). Submittal date: 04/14/2000. 
162713 MO0210PGVPB107.000. Design Peak Ground Velocity for the Repository Level 
(Point B) at 10-7 Annual Exceedance Probability. Submittal date: 10/17/2002. 
161513 MO0211AVTMH107.001. Acceleration, Velocity, and Displacement Spectrally 
Conditioned Time Histories for the Repository Level at 10-7 Annual Exceedance 
Frequency. Submittal date: 11/12/2002. 
161540 MO0211TMHIS104.002. Acceleration, Velocity, and Displacement Time Histories 
for the Repository Level at 5X10-4 Annual Exceedance Frequency. Submittal date: 
11/14/2002. 
164206 MO0212AVDSC106.000. Acceleration, Velocity, and Displacement Spectrally 
Conditioned Time Histories for the Repository Level at 10-6 Annual Exceedance 
Frequency. Submittal date: 12/09/2002. 
161868 MO0301TMHIS106.001. Acceleration, Velocity, and Displacement Time Histories 
for the Repository Level at 10-6 Annual Exceedance Frequency. Submittal 
date: 01/28/2003. 
162712 MO0303DPGVB106.002. Design Peak Ground Velocity for the Repository Level 
(Point B) at 10-6 Annual Exceedance Probability. Submittal date: 03/10/2003. 
163721 MO03061E9PSHA1.000. Spectral Acceleration and Velocity Hazard Curves 
Extended to 1E-9 Based on the Results of the PSHA for Yucca Mountain. Submittal 
date: 06/09/2003. 
ANL-WIS-MD-000005 REV 01 160 Features, Events and Processes: Disruptive Events 
164527 MO0307SEPFEPS4.000. LA FEP List. Submittal date: 07/31/2003. 
165880 MO0310INPDEFEP.000 PRE-1999 USGS and Los Alamos field observations at 
Yucca Mountain, Paiute Ridge, and Nevada Test Site used to Exclude DE FEPS. 
Submittal date: 10/16/2003. 
161 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
ATTACHMENT A 
GLOSSARY 
A-1 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
ATTACHMENT A 
GLOSSARY 
annual exceedance probabilityThe probability that a specified value (such as for ground motions 
or fault displacement) will be exceeded during one year. 
apertureThe gap between two walls or faces of a fracture. 
ash flowA density current, generally a hot mixture of volcanic gases and tephra that travels 
across the ground surface. The solid materials contained in a typical ash flow are generally 
unsorted and ordinarily include volcanic dust, pumice, scoria, and blocks in addition to ash. 
ash fallAirborne ash that falls from an eruption cloud, and the resulting deposit. 
asperityA measure of the roughness of the area of contact between two surfaces of a fracture. 
background earthquakeAn earthquake that does not produce ground breakage, hence is not 
associated with a known fault. Such earthquakes are considered to be random in time and space. 
In the Great Basin, background earthquakes have magnitudes of less than 6.0. 
basaltA dark-colored, fine-grained volcanic or intrusive rock (dike or sill intrusion) consisting 
chiefly of calcic plagioclase, pyroxene, and olivine. 
base levelThe theoretical lowest level toward which erosion progresses, considered practically 
as the level below which a stream cannot erode its bed. 
blind faultA fault that dies out in bedrock and is not exposed at earths surface. 
block faultingSegmentation of the crust into block-like masses by systematic normal faulting. 
caldera complexAn assemblage of extrusive and intrusive rocks and associated structures 
generated by explosive and effusive volcanism that comprise a number of genetically related 
overlapping or adjacent or proximal calderas. 
calicheA calcareous soil component typically forming friable to hard, off-white, crudely layered 
to finely laminated intervals near the surface of stony desert soils; several cm or more thick. 
Old, thick caliche intervals (calcretes) have the texture and hardness of concrete aggregate. 
colluvial slopeA hill slope mantled with loose, heterogeneous soil and rock fragments that are 
the result of weathering and accumulation by creep and unchanneled snow melt or runoff. 
conduitThe vertical or subvertical, essentially cylindrical, tube that brings magmatic material to 
land surface. Conduit is the appropriate term regarding the subsurface, and PA conceptual 
models emphasize the interactions that occur at the intersection of a conduit with the repository. 
A-2 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Crater Flat tectonic domainA tectonic domain is a block of the Earths crust bounded by major 
faults or zones of complex shear and deformation. A domain features a history and styles of 
deformation that distinguish it from adjacent areas of the crust. The Crater Flat domain includes 
Yucca Mountain and is characterized by normal faulting into the Crater Flat basin which lies 
immediately to the west of Yucca Mountain. 
debris flowA moving mass of rock fragments and mud, comprised mostly of fragments larger 
than sand size; water-mobilized colluvium; also the deposit of such a flow. 
detachment faultingA style of normal faulting wherein large, extensional displacement occurs 
on a fault plane that dips less than 30. In places, the lower plates (footwalls) of detachment 
faults have been uplifted from mid-crustal depths, implying that detachment is accompanied by 
significant isostatic uplift or uplift by magmatic inflation. 
dikeA tabular intrusion of magma that is at a high angle to layering in the intruded strata (i.e., 
vertical or subvertical at Yucca Mountain). 
dike systemOne or more dikes that are closely related in space and time. Dike systems may 
include multiple dikes that share a common magmatic source with a single volcano. This 
definition does not preclude the possibility that a dike system may feed more than one volcano. 
dip-slip faultingFaulting in which the hanging wall moves down the dip of the fault plane. 
Normal faulting has slip directly along the dip normal to the strike of the fault; oblique faulting 
has a component of slip parallel to the fault strike (i.e., some lateral displacement). 
disruptive FEPAn Included FEP that has a probability of occurrence during the period of 
performance less than 1.0 (but greater than the cutoff of 10-4/104 year). 
disruptive event scenario classThe scenario class, or set of related scenarios classes, that 
describes the behavior of the system if perturbed by disruptive events. The disruptive scenario 
classes contain all disruptive FEPs that have been retained for analysis. 
eruptive event (with respect to repository performance)The formation of a volcano that includes 
at least one subsurface conduit that intersects a drift containing waste packages. 
eventA natural or anthropogenic phenomenon that has the potential to affect disposal-system 
performance and that occurs during an interval that is short compared to the period of 
performance. 
Excluded FEPA FEP that is identified by the FEP screening process as not requiring modeling 
in the quantitative TSPA. 
expected FEPAn Included FEP that, for the purposes of the TSPA, is presumed to occur with a 
probability equal to 1.0 during the period of performance. 
extrusive event (with respect to repository performance)Synonymous with eruptive event. 
A-3 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
faultingProcess of fracture and attendant slip along a fracture plane or recurrent slip along a 
such a plane. 
fault strandA fault segment expressed as a continuous intersection with the earths surface, as 
indicated by a scarp, scarp line, or series of exposed displacement features, all having the same 
style of offset. A fault strand is generally taken to connote a relatively short fault segment or 
splay that is one of a series of many faults that together form the principal fault zone. The 
zone is usually not straight and well developed, and faults may bifurcate or anastomose or step 
over from one fault to another. Slip can be transferred across many strands. 
featureAn object, structure, or condition that has a potential to affect disposal-system 
performance. 
flowing intervalA fracture or fractured zone that transmits flow in the SZ. 
foldingBending in strata. Formation of folds expressed by geometric features that include fold 
limbs, fold axes, and axial planes. Large or systematic compressive and drag folds are results of 
tectonic activity. 
fractureA brittle crack in rock. Groups of fractures in more or less regular orientation and 
spacing are termed joints. Fractures form by bending (shear joints) or tension or principal stress 
reduction (extension joints). Cooling joints are formed by tension exerted by contraction as an 
intrusive or extrusive volcanic rock cools. 
futureA single, deterministic representation of the future state of the system. An essentially 
infinite set of futures can be imagined for any system. 
geodetic strain rateRegional strain rate determined at the earths surface by repeated 
measurement of displacements of precisely located landmarks (monuments) embedded in the 
deforming medium. 
geologic settingThe geologic, hydrologic, and geochemical systems of the region in which a 
geologic repository is or may be located. 
geothermal gradientThe rate of increase of temperature with depth in the earth 
heat flowThe amount of heat energy leaving the earths crust, measured in Heat Flow Units 
(HFU) or calories/m2/sec. 
hydrovolcanic eruptionVery energetic explosive eruptions triggered by the rapid mixing of 
ground or surface water with rising magma eruptions. Rather than formation of scoria cones by 
ballistic deposition, tephra and lithic clasts are deposited as fallout and pyroclastic density 
currents leaving surge deposits and typically forming wide, shallow tuff rings. 
igneous activityAny process associated with the generation, movement, emplacement, or 
cooling of molten rock within the earth or on the earths surface. 
A-4 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
Included FEPA FEP that is identified by the FEP screening process as requiring analysis in the 
quantitative TSPA. 
intrusive event (with respect to repository performance)An igneous structure (such as a dike, 
dike system, or other magmatic body in the subsurface) that intersects the repository footprint at 
the repository elevation. 
key blockCritical blocks formed in the rock mass surrounding an excavation (by the 
intersection of three or more planes of structural discontinuity). These blocks are capable of 
displacement so that they are likely to move into the drift opening unless restraint is provided. 
lithophysaeA subrounded cavity from about one to several cm in diameter formed in silicic 
volcanic rocks (e.g., welded tuff) by gas bubbles evolved during cooling; lithophysae are 
typically lined or largely filled with finely crystalline or cryptocrystalline rinds of secondary, 
vapor-phase minerals. 
maarA low-relief, broad volcanic crater formed by shallow explosive eruptions. The explosions 
are usually caused by the heating and boiling of groundwater resulting from magma invading the 
groundwater table. 
magmaPartially or completely molten rock within the earths crust or mantle. 
magmatic inflationUplift of the crust caused by intrusion of subjacent magma, which can occur 
due to large-volume batholithic melts, dike swarms, or lower crustal magmatic underplating. 
mantleThe zone of the earth below the crust and above the core, typified by high seismic 
velocity and dense iron- and magnesium-rich silicate mineral components. 
mantle plumeA large mass of molten mantle material rising up from the lower mantle into the 
base of the crust by the process of convection and buoyancy. Mantle plumes are typically 
hundreds of km in area. 
MioceneEpoch of the Tertiary Period between 24 Ma and 5 Ma. 
modeling caseA well-defined, connected sequence of FEPs that can be thought of as an outline 
of a future condition of the repository system. Modeling cases can be undisturbed, in which case 
the performance would be the expected, or nominal, behavior for the system. Modeling cases 
can also be disturbed, if altered by disruptive events such as human intrusion or natural 
phenomena such as volcanism, seismicity, or nuclear criticality. 
nominal scenario classThe scenario class, or set of related scenarios classes, that describes the 
expected or nominal behavior of the system as perturbed only by the presence of the repository. 
The nominal scenario class contains all expected FEPs that have been retained for analysis. 
nonwelded unitA volcanic ash, or tuff, that is crumbly or easily excavated because the 
component glass shards did not weld together during compaction of relatively cool ash or ash 
having relatively sparse glass content. 
A-5 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
paleoseismic slipThe amount of fault slip indicated by buried offset strata; individual 
paleoearthquakes are indicated by discrete amounts of offset. 
percolation flowFlow of groundwater through small, interconnected rock or soil pores. 
playaA dried lake bed. Playas have, typically, a flat, salty surface that forms the low part of a 
confined desert basin. 
PleistoceneThe epoch of the Quaternary Period from about 1.6 Ma to 10 Ka. 
Plio-PleistoceneCombined duration of the Pliocene and Pleistocene epochs of the Cenozoic era, 
from 10 Ka to 5 Ma. 
potentiometric surface A notional surface representing the total head of groundwater as defined 
by the level at which such water stands in a well. The water table is a particular type of 
potentiometric surface pertaining to an unconfined aquifer in which the surface is in equilibrium 
with atmospheric pressure. 
processA natural or anthropogenic phenomenon that has the potential to affect disposal-system 
performance and that operates during all or a significant part of the period of performance. 
pumiceHighly vesicular or frothy siliceous glass formed during volcanic eruption; typically a 
pale gray color. 
pumiceousHaving observable pumice content. 
pyroclasticPertaining to clastic rock material formed by volcanic explosion or aerial expulsion 
from a volcanic vent. 
QuaternaryThe period of the Cenozoic Era from 1.6 Ma to present includes the Pleistocene and 
Holocene Epochs. 
reference biosphereThe description of the environment inhabited by the reasonably maximum 
exposed individual (RMEI). The reference biosphere comprises the set of specific biotic and 
abiotic characteristics of the environment, including but not necessarily limited to, climate, 
topography, soils, flora, fauna, and human activities. 
regional slopeThe surface defined by the elevations of resistant peaks in a given area; it 
approximates the surface formed by uplift prior to erosional incision. 
regional subsidenceBroad depression of the earths surface resulting from tectonic activity such 
as extension, crustal cooling, or deep crustal or mantle flow. 
regional upliftBroad elevation of the earths surface resulting from tectonic activity such as 
compression or igneous intrusion. 
A-6 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
rockburstA sudden and often violent failure of masses of rocks in quarries, tunnels, or mines. It 
is an uncontrolled disruption of rock associated with a violent release of energy additional to that 
derived from falling rock fragments. 
rolloverA steepening of dip in the downthrown block of a normal fault as the fault plane is 
approached. 
scenario classA set of related modeling cases that share sufficient similarities that they can 
usefully be aggregated for the purposes of screening or analysis. The number and breadth of 
scenario classes depends on the resolution at which modeling cases have been defined. Coarsely 
defined modeling cases result in fewer, broad scenario classes, whereas narrowly defined 
modeling cases result in many narrow scenario classes. Scenario classes (and modeling cases) 
should be aggregated at the coarsest level at which a technically sound argument can be made, 
while still maintaining adequate detail for the purposes of analysis. 
seismic activityThe recurrence and distribution of earthquakes associated with a specified 
seismic source. 
seismicityThe capacity of a fault, group of faults, or region of the crust to generate earthquakes, 
as determined by instrumental or paleoseismic history; the relative rate at which earthquakes 
recur (syn. seismic activity). 
springlineThe imaginary line at which an arch, vault, or drift begins to curve; for circular crosssections, 
this corresponds to the vertical mid-point along the drift wall. 
stopingIn the FEPs context, this term is used to mean the progressive, generally upward, 
breaking and removal of rock along a drift, fracture, fault, or other feature due to natural causes. 
strain rateThe rate at which a unit of length is shortened or lengthened under a stress load, 
usually given in terms of inverse seconds. Strain rate is often expressed in units of mm/yr where 
an actual length difference rather than a ratio is calculated. 
strandSee fault strand. 
stream gradientAngle between inclination of a stream channel bed and the horizontal measured 
in direction of flow (i.e., the slope of a stream). 
subducting slabA section of oceanic (basaltic) crust in process of being drawn down into the 
upper mantle by tectonic forces as crustal plates interact. 
tectonic activityThe dynamic manifestation of stress loads generated within the earths crust 
(e.g., igneous intrusion, earthquakes, uplift). 
tectonic deformationThe suite of geological structures generated by body stresses exerted 
within the earths crust; such structures range in scale from microscopic (e.g., mylonite fabric) to 
regional (e.g., overthust belts). Also, the process by which such structures together is formed. 
A-7 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
tectonic extensionStretching or extension of the crust as a result of deep-seated tectonic stress, 
such as back-arc spreading. 
tectonic processThe dynamic evolution of structure generated through the buildup and 
relaxation of regional stress. 
tectonismAll movement of the crust produced by tectonic processes, including mountain 
building (orogeny), regional uplift and subsidence; the general expression of tectonic process 
through time and space. 
tephraA collective term used for all pyroclastic material, regardless of size, shape or origin, 
ejected during an explosive volcanic eruption. Originally applied exclusively to fallout ejecta, 
but now also applies to pyroclastic flow deposits. 
errain reliefFor some defined area of the earths surface, it is the measure of difference between 
the lowest local elevation and the highest local elevation. 
topographyThe physical features of a district or region, such as are represented on maps, taken 
collectively; especially the relief and contour of the land. 
Type I faultFaults or fault zones that are subject to displacement and are of sufficient length and 
location that they may affect repository design or performance. 
ventThe intersection of a conduit with land surface. Volcanoes may have more than one vent. 
vertical axis rotationFolding referenced to a vertical axis. Hence, folded beds or layers change 
strike around the inferred vertical axis. 
violent strombolian eruptionvolcanic eruptions with violent blasts that project voluminous 
showers of scoria and bombs to heights of hundreds or thousands of feet, accompanied by a 
dense black ash cloud. Violent strombolian eruptions are characterized by vertical eruption of a 
high-speed jet of a gas-clast mixture. 
volcanic activityThe suite of events and processes associated with extrusion of molten rock, 
such as eruption, lava emission, or cone formation comprising the subaerial components of 
igneous activity. 
volcanic eventThe formation of a volcano (with one or more vents) resulting from the ascent of 
basaltic magma through the crust as a dike or system of dikes. 
volcanoA geologic feature than includes an edifice of magmatic material erupted on the land 
surface, one or more conduits that feed the eruption, and a dike or dike system that feeds the 
conduit or conduits. 
water tableThe surface of unconfined groundwater at which the pressure is equal to that of the 
atmosphere. 
A-8 ANL-WIS-MD-000005 REV 01 Features, Events and Processes: Disruptive Events 
welded unitA volcanic ash, or tuff, that is strongly indurated because hot glass shards were 
partially melted together (welded) during compaction of the ash bed while the ash was still hot. 
ANL-WIS-MD-000005 REV 01 A-9