October 17, 2000

Mr. James H. Carlson, Acting Director

Program Management and Administration

Office of Civilian Radioactive Waste Management

U.S. Department of Energy

1000 Independence Avenue, SW

Washington, DC 20585

SUBJECT: U.S. NUCLEAR REGULATORY COMMISSION’S OBSERVATION AUDIT

REPORT NO. OAR- 00-09, “OBSERVATION AUDIT OF OFFICE OF THE

CIVILIAN RADIOACTIVE WASTE MANAGEMENT, QUALITY ASSURANCE

DIVISION, AUDIT NO. M&O-ARP-00-08"

Dear Mr. Carlson:

I am transmitting the U.S. Nuclear Regulatory Commission’s (NRC’s) Observation Audit Report

No.OAR-00-09 of the U.S. Department of Energy (DOE), Office of Civilian Radioactive Waste

Management (OCRWM), Office of Quality Assurance (OQA), Yucca Mountain Quality

Assurance Division, audit of the Near Field Environment (NFE) Process Model Report (PMR)

activities performed by the OCRWM Management and Operating Contractor (M&O). The audit,

M&O-ARP-00-08, was conducted on July 24-28, 2000, at the M&O facilities in Las Vegas,

Nevada.

The scope of the audit was limited to evaluating the effectiveness of the implementation of the

OCRWM Quality Assurance Program described in the “Quality Assurance Requirements and

Description” and its implementing procedures for selected analysis model reports (AMRs)

supporting the NFE PMR.

The NRC observers determined that OQA Audit M&O-ARP-00-08 was effective in determining

the level of compliance of M&O activities associated with the NFE PMR. The NRC observers

agreed with the audit team’s conclusions, findings, and recommendations as presented at the

audit exit. Within the areas evaluated, the audit team identified potential deficiencies in: a)

software routines not containing sufficient information; b) input data and assumptions not being

clearly stated and justified; and c) the scope of the CAL (Calculation) document exceeded that

allowed by the procedure.

As discussed in the attached report, the observers identified and discussed their findings during

the course of the audit. The most significant observer concern is that certain aspects of the two

AMRs and the one CAL audited were found to be technically insufficient for either the intended

purpose or for supporting the stated conclusions. The specific potential deficiencies and/or

recommendations are detailed in the sections pertaining to the individual AMRs and CAL. The

DOE audit team Technical Specialists identified these potential deficiencies and/or

recommendations and brought them to the attention of the originators, and the NRC staff

concurred with those findings. The NRC observers generated no audit observer inquiries

(AOIs) during this audit.

J. Carlson - 2 -
A written response to this letter and the enclosed report is not required. If you have any

questions, please contact Ted Carter of my staff at (301) 415-6684.

Sincerely,

/ra/

Janet Schlueter, Chief (Acting)

High-Level Waste Branch

Division of Waste Management

Office of Nuclear Material Safety

and Safeguards

Enclosure: NRC Observation Audit Report No. OAR-00-09, “Observation Audit of the Office

of Civilian Radioactive Waste Management, Quality Assurance Division, Audit

No. M&O-ARP-00-08"

cc See attached list.
Letter to J. Carlson from J. Schlueter dated: Oct. 17, 2000

cc: R. Loux, State of Nevada

S. Frishman, State of Nevada

L. Barrett, DOE/Wash, DC

A. Brownstein, DOE/Wash, DC

S. Hanauer, DOE/Wash, DC

C. Einberg, DOE/Wash, DC

J. Carlson, DOE/Wash, DC

N. Slater, DOE/Wash, DC

A. Gil, DOE/Las Vegas, NV

R. Dyer, YMPO

S. Brocoum, YMPO

R. Clark, YMPO

C. Hanlon, YMPO

T. Gunter, YMPO

G. Dials, M&O

J. Bailey, M&O

D. Wilkins, M&O

M. Voegele, M&O

S. Echols, Winston & Strawn

B. Price, Nevada Legislative Committee

J. Meder, Nevada Legislative Counsel Bureau

D. Bechtel, Clark County, NV

E. von Tiesenhousen, Clark County, NV

A. Kalt, Churchill County, NV

G. McCorkell, Esmeralda County, NV

L. Fiorenzi, Eureka County, NV

A. Remus, Inyo County, CA

B. Duke, Lander County, NV

J. Pitts, Lincoln County, NV

J. Wallis, Mineral County, NV

L. Bradshaw, Nye County, NV

M. Murphy, Nye County, NV

J. McKnight, Nye County, NV

B. Ott, White Pine County, NV

D. Weigel, GAO

W. Barnard, NWTRB

R. Holden, NCAI

A. Collins, NIEC

R. Arnold, Pahrump County, NV

J. Lyznicky, AMA

R. Clark, EPA

F. Marcinowski, EPA

R. Anderson, NEI

R. McCullum, NEI

S. Kraft, NEI

J. Kessler, EPRI

D. Duncan, USGS

R. Craig, USGS

W. Booth, Engineering Svcs, LTD

J. Curtiss, Winston & Strawn

J. Curtiss, Winston & Strawn

J. Carlson - 2 -
A written response to this letter and the enclosed report is not required. If you have any

questions, please contact Ted Carter of my staff at (301) 415-6684.

Sincerely,

Janet Schuleter, Chief (Acting)

High-Level Waste Branch

Division of Waste Management

Office of Nuclear Material Safety

and Safeguards

Enclosure: NRC Observation Audit Report No. OAR-00-09, “Observation Audit of the Office

of Civilian Radioactive Waste Management, Quality Assurance Division, Audit

No. M&O-ARP-00-08"

cc: See attached list.

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(Initials) (Date)
U.S. NUCLEAR REGULATORY COMMISSION

OBSERVATION AUDIT REPORT NO. OAR-00-09

OBSERVATION AUDIT OF THE

OFFICE OF CIVILIAN RADIOACTIVE WASTE MANAGEMENT

QUALITY ASSURANCE DIVISION

AUDIT NO. M&O-ARP-00-08

/ra/ 10/16/00 /ra/ 10/13/00

Ted Carter Lauren Browning

Projects and Engineering Section Center for Nuclear Waste Regulatory

High-Level Waste Branch Analyses

Division of Waste Management

/ra/ 10/13/00 /ra/ 10/13/00

Debra Hughson Goodluck Ofoegbu

Center for Nuclear Waste Regulatory Center for Nuclear Waste Regulatory

Analyses Analyses

Reviewed and Approved by:

/ra/ 10/17/00

N. King Stablein, Chief

Projects and Engineering Section

High-Level Waste Branch

Division of Waste Management

Enclosure
1

1.0 INTRODUCTION

Staff from the U.S. Nuclear Regulatory Commission (NRC) Division of Waste Management and

contractors from the Center for Nuclear Waste Regulatory Analyses (CNWRA) observed the U.S.

Department of Energy (DOE), Office of Civilian Radioactive Waste Management (OCRWM),

Office of Quality Assurance (OQA), Yucca Mountain Quality Assurance Division performancebased audit of the Near Field Environmental (NFE) Process Model Report (PMR) activities

performed by the OCRWM Management & Operating Contractor (M&O). The audit, M&O-ARP00-08, was conducted on July 24-28, 2000, at the M&O facilities in Las Vegas, Nevada.

The objective of this audit was to evaluate the implementation of the applicable provisions

contained in the OCRWM Quality Assurance Requirements and Description (QARD), DOE/RW0333P, Revision 8, by reviewing selected Analysis Model Reports (AMRs) and other documents

supporting the NFE PMR. During the audit, selected AMRs and a Calculation (CAL) document

were subjected to a technical and programmatic review to ensure that the applicable

requirements contained in the QARD were met.

The NRC staff objective was to gain confidence that the M&O and OQA are properly

implementing the provisions contained in the QARD and the requirements contained in Subpart

G, “Quality Assurance,” to Part 60, of Title 10 of the U.S. Code of Federal Regulations (10 CFR

Part 60). Because of the anticipated DOE submittal of the Site Recommendation Consideration

Report (SRCR) in December 2000, the following observation activities were emphasized: (1)

confirming that data, software, and models supporting the SRCR are properly qualified; and (2)

reviewing the progress being made by DOE and its contractors in meeting the qualification goals

for SRCR.

This report addresses the NRC staff determination of the effectiveness of the OQA audit and the

adequacy of implementation of QARD controls by the M&O in the audited areas of AMR

development.

2.0 MANAGEMENT SUMMARY

The NRC staff has determined that OQA Audit M&O-ARP-00-08 was useful, effective, and

conducted in a professional manner. Audit team members were independent of the activities they

audited and appeared to be knowledgeable in the quality assurance (QA) and technical

disciplines within the scope of the audit. The audit team members’ qualifications were reviewed

and the members were found to be qualified in their respective disciplines.

The audit team concluded that the OCRWM QA program had been satisfactorily implemented in

the areas evaluated. However, five potential deficiencies were identified during the audit, and

approximately 27 recommendations were offered for improvements and enhancements to the

AMRs. Within the areas evaluated, the audit team identified potential deficiencies in: a) software

routines not containing sufficient information; b) input data and assumptions not being clearly

stated and justified; and c) the scope of the CAL document exceeded that allowed by the

procedure. The NRC staff determined that this audit was effective in identifying the deficiencies

and recommending improvements in the AMRs. The NRC staff also agrees with the audit team

conclusions, findings, and recommendations.
2

3.0 AUDIT PARTICIPANTS

3.1 Nuclear Regulatory Commission Observers

Ted Carter Observer (Team Leader-NRC)

Debra Hughson Observer (Technical Specialist-CNWRA)

Lauren Browning Observer (Technical Specialist-CNWRA)

Goodluck Ofoegbu Observer (Technical Specialist-CNWRA)

3.2 OQA Audit Team

Robert Hartstern Audit Team Leader OQA/Quality Assurance Technical

Support Services (OQA/QATSS)

Steve Harris Auditor OQA/QATSS

Richard Weeks Auditor OQA/QATSS

Chet Wright Auditor OQA/QATSS

William Roberds Technical Specialist DOE/MTS

David Sassani Technical Specialist DOE/MTS

4.0 REVIEW OF THE AUDIT AND AUDITED ORGANIZATION

This OQA audit of the M&O was conducted in accordance with OCRWM Quality Assurance

Procedure (QAP) 18.2, “Internal Audit Program,” and QAP 16.1Q, “Performance/Deficiency

Reporting.” The NRC staff’s observation of this audit was based on the NRC draft procedure,

“Conduct of Observation Audits,” issued October 6, 1989 (Draft).

4.1 Scope of the Audit

The audit team conducted a limited-scope, performance-based audit of activities and processes

related to the development of the AMRs supporting the NFE PMR. AMRs, software, and data

were evaluated during the audit process. The audit included review of the programmatic controls

governing the AMRs and technical issues discussed in the AMRs. Specifically, the following two

AMRs and one CAL supporting the NFE PMR were reviewed by the audit team and the NRC

observers during the audit:

Analysis Model Reports

ˇ N000 Thermal Tests Thermal-Hydrological (TH) AMR (ANL-NBS-TH-000001), Rev 00

ˇ N0120 Drift-Scale Coupled Processes Models (Drift Scale Test (DST) and TH-Chemical

Seepage) (MDL-NBS-HS-000001), Rev 00

Calculation

ˇ CAL-NBS-MD-000002-00: Premeability Change Due To Coupled TH-Mechanical Effects, Rev

00 (Tracking Number - N0C30)
3

4.2 Conduct and Timing of the Audit

The audit was performed in a professional manner and the audit team demonstrated a sound

knowledge of the applicable M&O and DOE programs and procedures. Audit team personnel

were persistent in their interviews, challenged responses when appropriate, and performed an

acceptable audit. The NRC staff believes the timing of the audit was appropriate for the auditors

to evaluate the effectiveness of the analyses and models process for the NFE PMR and the

quality of resultant end products.

The DOE audit team and NRC observers caucused at the end of each day. Also, meetings of the

audit team and M&O management (with the NRC observers present) were held each morning to

discuss the current audit status and preliminary findings.

4.3 Audit Team Qualification and Independence

The qualifications of the DOE audit team leader and the OQA audit team members were found to

be acceptable in that they met the requirements of QAP 18.1, “Auditor Qualification,” as verified

by the NRC observation audit lead. The audit team members did not have prior responsibility for

performing the activities they audited. In addition, training, education, and experience records for

audit team members were reviewed and found acceptable. Further, the NRC observer reviewed

the technical specialists’ qualifications (resumes) and found that the technical specialists had

sufficient technical education, training, and experience related to the AMRs reviewed.

4.4 Examination of QA Programmatic Elements

The OQA programmatic and technical audit activities were conducted simultaneously, using subaudit teams consisting of a technical specialist and a QA auditor. The limited-scope audit

focused on the QA elements closely associated with the development of the AMRs. The NRC

staff observed that each of the auditors reviewed related documentation and interviewed a

representative sample of M&O personnel to determine their understanding of implementing

procedures and processes. Training, education, and experience records were reviewed to

assure M&O personnel were in compliance with their individual position descriptions. Objective

evidence was provided and reviewed by the auditor and it was determined that all personnel were

in compliance.

4.5 Examination of Technical Activities

The DOE audit team prepared detailed checklists for the CAL and each of the AMRs. Technical

activities examined by the audit team, and in some cases those questions forwarded to the audit

team, are summarized below for the CAL and each of the AMRs.

AMR N0000, Thermal Tests Thermal-Hydrological Analyses/Model Report (Rev 00, 04/00)

As stated in the AMR, the report had two purposes. First, the AMR was to evaluate the drift scale

TH property set derived from the unsaturated zone (UZ) flow and transport analyses for thermally

perturbed conditions. Second, the AMR was to conduct sensitivity studies of other TH property

sets, including the mountain scale TH property set, and investigate modifications that would result

in adequate agreement between simulated and measured TH data. However, the AMR did not

fulfill all the purposes as defined in the AMR development plan (CRWMS M&O, 1999). The
4

development plan requires the AMR to recommend a property set for thermally perturbed flow

and transport in the UZ.

The DOE Technical Specialist/auditor (hereafter referred to as the DOE auditor) found that this

purpose as stated in the development plan had not been met. The NRC observer concurred with

this finding. Specifically, the DOE auditor noted that quantitative comparisons between

simulations and test results were made only for temperature data while simulated hydrological

responses for thermally perturbed flow and saturations detected by geophysical techniques in the

test environments were characterized in the AMR only subjectively as being in “good agreement.”

In addition, the significantly differing moisture distributions simulated using the various property

sets indicated to the DOE auditor that this AMR did not succeed in discriminating between

various TH property sets for predicting hydrological responses to thermal perturbations for use in

PA. The DOE auditor pointed out that measured and simulated temperatures were compared

quantitatively by weighted statistical measures but the criteria by which the comparisons were

deemed acceptable were subjective and not adequately justified. Finally, the DOE auditor noted,

and the NRC observer concurred, that the criteria for acceptable matches between simulations

and temperature data were set so that all the property sets were found to be acceptable.

The DOE auditor also found the following additional potential deficiencies and/or

recommendations in this AMR during the audit.

• Although the purpose of this AMR was to evaluate property sets for thermally perturbed flow

and transport in the UZ, only one unit, the middle non-lithophysal unit of the Topopah Spring

Tuff which comprises about 10 percent of the proposed repository, was investigated.

• Assumptions about boundary and initial conditions were not clearly stated nor justified and

appeared to be inconsistent.

• Focusing of condensate drainage and preferential flow in fractures is observed in the thermal

tests and is acknowledged to be the source of water collecting in several boreholes at the

DST. This phenomenon is a mechanism by which water may enter drifts during the thermal

period and may be important to performance, yet this AMR neglects spatial heterogeneity.

The water collected and removed from boreholes in the DST is not included in the models.

• Leakage through the thermal bulkhead of the DST was not well represented by the models.

The AMR acknowledged that leakage through the bulkhead remains one of the largest

uncertainties in the DST results.

The NRC observer agreed with these findings as they were conveyed to the AMR originators

during the audit. NRC recommends that DOE more thoroughly evaluate thermally driven

moisture redistribution, such as focused condensate drainage through fractures, that are

important to repository performance.

CRWMS M&O 1999, Thermal Test Thermal-Hydrological Analysis and Models Report,

DI#ANL–NBS–TH–000001. TDP–NBS–TH–000002, Rev. 0 ICN 0. Las Vegas, Nevada, CRWMS

M&O. ACC: MOL.20000124.0319.

AMR N0120, Drift-Scale Coupled Processes (DST and THC Seepage) Models, Rev 00

This report evaluated coupled thermal-hydrologic-chemical (THC) processes associated with the
5

DST, and then extended the model calculations to time frames appropriate for the evaluation of a

potential waste-emplacement drift at Yucca Mountain, NV. Analytical data from the DST were

used to appraise the conceptual and numerical models. Results from this study will be used as

input for the performance assessment, “UZ Flow and Transport PMR,” and the NFE PMR.

Although this AMR used state-of-the-art techniques, several limitations and areas for

improvement were identified by the DOE auditor. The NRC observer concurred with all technical

recommendations made by the DOE auditor/technical specialist. The following paragraphs

summarize those technical recommendations.

The following model assumptions should be explicitly stated and supported by stronger technical

bases:

• Reaction rates of most minerals in the systems described by Cases 1 and 2 of this AMR are

known to be pH dependent. However, the DOE observer/technical specialist noted that this

AMR employs a simplified version of the rate law that does not account for non-linear

variations in effective reaction rates due to H+ dependency. The intrinsic rate constants were

calculated assuming a fixed pH of 7. It is assumed in this AMR that these simplifications will

have negligible effects on the model results. The NRC observer concurs with the DOE

auditor/technical specialist that this assumption should be explicitly stated, and that technical

bases should be given to support a specific pH range under which these assumptions are

valid.

• Current design specifications require 70 percent heat removal by ventilation, but the DOE

auditor/technical specialist noted that this AMR assumes 50 percent heat removal in

calculations of effective thermal conductivities. The DOE auditor/technical specialist

recommended that this discrepancy in heat loss be clearly indicated in the text, and that an

impact analysis should be performed to evaluate the effects on the model results. The NRC

observers agree with this recommendation, and also noted that the discussion of heat

removal in this AMR lacks appropriate references. The DOE auditor/technical specialist

recommended that appropriate references be included.

• The following model assumption should be explicitly stated: Aqueous fluid properties may be

affected by changes in dissolved constituent concentrations over a range of temperatures. In

this AMR, these effects are assumed to be negligible. The DOE auditor/technical specialist

recommended that this assumption be explicitly stated in Section 5, and the NRC technical

observer agreed.

Several modifications should be made to the text to improve its transparency. These are

explained below.

• The DOE auditor noted that modifications to the rate law given in Equation 8 are likely to have

a significant effect on the model results, and recommended that these modifications be

explicitly described in the AMR (not just the scientific notebook). The NRC observer

concurred.

• The DOE auditor identified incorrect values of the fracture reactive surface area for the units

“ptnf3" and “tswf7" in Table III-I of this AMR. Although these errors were not propagated into

the model input files, the DOE technical specialist and the NRC observer agreed that these

values must be corrected in the AMR.
6

• The DOE auditor recommended that direct linkage to data derivation be improved by adding

input Tables and Data Tracking Numbers to DIRS and then removing the Data Tracking

Numbers and Input Tables from the list of model outputs in Section 8.4. These modifications

were requested for Table 4 and Attachments II-IV. The NRC observer agreed with this

recommendation.

This AMR addressed model validation by comparing model predictions with measured

parameters from the DST. Several recommendations were made to strengthen this comparison

and increase confidence in long-term predictions of the THC Seepage model. These

recommendations are explained below.

• The NRC observer noted that a number of water and gas samples from the DST were

analyzed, but many of these were not used as benchmarks for comparison with model

predictions. The NRC observer was concerned that the measurements used in this AMR may

not be representative. Alternatively, measurements that were not used in this AMR may

reflect important processes that need to be considered. The DOE auditor agreed, and

recommended that the full range of water and gas samples be evaluated to determine which

measurements, if any, should be excluded from further consideration. Both the DOE auditor

and the NRC observer emphasized that all assumptions used in the evaluation of water

analyses should be stated explicitly and supported by technical bases.

• The DOE auditor/technical specialist and the NRC observer agreed that additional data for

uncertainty analyses are needed to strengthen the Case 2 comparison against DST

measurements. Because model validation relies on a comparison with analytical water and

gas compositions, the DOE auditor recommended that the reliability of these data be

assessed in a quantitative fashion. This AMR included some discussion of data uncertainties

and limitations, but more comprehensive evaluations should be performed to strengthen the

validation of the THC Seepage model. Uncertainties may stem from the analytical

measurements themselves or from incomplete knowledge about the physical location(s) and

condition(s) that contributed to the measured values. Data uncertainties should be evaluated,

and corresponding bounds should placed on model results.

• Both the DOE auditor and the NRC observer were concerned that simulations performed

using extended (Case 1) and abbreviated (Case 2) sets of minerals led to incongruous

results. The NRC observer concurs with the DOE auditor that stronger technical bases are

needed to support the conclusion that Cases 1 and 2 approaches are well-suited to predict

THC processes over different time frames. Case 2 provides a closer match with the DST

measurements than Case 1, and is used to validate the model over short time frames.

However, the NRC observer noted that the explanation given for excluding Case 1 as a

benchmark for comparison with the DST measurements p. 57( i.e. uncertainties in

thermodynamic and kinetic data) can be applied equally well to Case 2. The DOE auditor and

the NRC observer agreed that additional work is needed to reconcile differences between

Case 1 and Case 2 results. The DOE auditor/technical specialist recommended that

additional sensitivity studies be performed to identify the input parameters that contribute

most significantly to model uncertainties, and to place bounds on the model results. The NRC

observer concurred with these recommendations.

Calculation CAL–NBS–MD–000002–00: “Permeability Change Due To Coupled ThermalHydrological-Mechanical Effects” (Tracking Number - N0C30)

This report described a calculation performed to provide a bounding estimate of fracture

permeability change owing to thermal-mechanical effects at the proposed Yucca Mountain

repository. The estimate would be used to support PA abstractions of drift seepage and the NFE
7

PMR. Results from the calculation were used to suggest that thermal-mechanical effects on

permeability would be limited to a permeability increase by a factor of 10 or less within a zone

extending up to two drift diameters from a drift wall. However, the NRC observer concurred with

the DOE auditor that the calculation is inadequate to support such a conclusion for the following

reasons.

The mechanical model used for the calculation did not represent the anticipated mechanical

environment at the proposed repository. The model used for the calculation consisted of a

rectangular prism 60m-high (vertically), 30m-wide, in the drift direction, and 50m-wide in the driftnormal direction. The emplacement drift was represented by a horizontal circular opening, 5.5m

in diameter and 30m-long, which is located at the mid-height of the prism. The applied

mechanical boundary conditions consisted of zero vertical displacement at the base (i.e., at 30m

below the emplacement-drift axis) and zero stress change on all other surfaces. The value of

fixed stress at the stress boundary surfaces was set equal to the initial in-situ stress (i.e., before

thermal loading) for the repository depth. These boundary conditions permitted free thermal

expansion of the heated domain and, consequently, the resulting stress states are substantially

different from the anticipated stress states during the thermal regime at Yucca Mountain. For

example, the maximum principal compressive stress calculated from the model remained vertical

throughout a 1000-year simulation period. On the other hand, the maximum principal

compressive stress was expected to be horizontal during the thermal regime at Yucca Mountain

because of higher restraint in the lateral than vertical direction. The document originator

explained that the boundary conditions were chosen to promote rock loosening and, therefore,

maximum permeability increase, in the roof area of the emplacement drift. However, thermalmechanical models of the repository, with boundary conditions that appropriately represented the

anticipated mechanical environment, indicated that stress-driven slip on subhorizontal fractures is

an important mechanism of permeability change. The NRC observer concurred with the DOE

auditor that, because of focusing on a mechanism that is inconsistent with the anticipated

mechanical environment at Yucca Mountain, the calculation may produce nonconservative

conclusions regarding the magnitude of potential permeability change and the geometrical

characteristics of the zones of such change.

The fracture pattern at Yucca Mountain was represented in the model as three orthogonal (i.e.,

two vertical and one horizontal) fracture sets. This fracture pattern was different from the pattern

used in previous DOE analyses of thermal-mechanical effects. The analyses presented in each

of the following previous DOE documents were based on nonorthogonal fracture sets with dips of

about 80 degrees for each of two subvertical sets and about 20 degrees for a subhorizontal set:

”Exploratory Studies Facility (ESF) Ground Support Design”

(BABEE0000–01717–0200–00002–00D); “Seismic Topical Report II” (YMP/TR–003–NP–2); “Drift

Ground Support Design Guide” (BCAA00000–01717–2500–00001–00); “Repository Ground

Support Analysis for Viability Assessment” (BCAA00000–01717–0200–00004–01); and the “Drift

Degradation Analysis AMR (ANL–EBS–MD–000027–00). The NRC observer concurred with the

DOE auditor that the use of a fracture pattern that is not representative of the fracture pattern at

Yucca Mountain may result in nonconservative conclusions regarding the magnitude of potential

permeability change.

The thermal-mechanical property values used in the analyses were inconsistent with values in the

DOE database. For example, the calculation used a thermal expansivity of 3 × 106

/K, whereas

thermal expansivity varies with temperature from about 7 × 106

/K at 25–50 degrees C, to about

20 × 106

/K at 225–250 degrees C, based on information in the “Yucca Mountain Site

Geotechnical Report” (B00000000–01717–5705–00043–01). Smaller values of thermal

expansivity gave smaller values of thermal stress. Therefore, the use of a value of thermal

expansivity that is small compared with values in the DOE database would lead to calculated

thermal stress that is small compared with the anticipated thermal stress based on information
8

from the DOE database. Smaller stresses imply reduced magnitudes of inelastic response and,

therefore, permeability change. Therefore, the NRC observer concurred with the DOE auditor

that the potential deficiencies in the audited calculation may produce nonconservative

conclusions regarding the magnitude of potential permeability change.

4.6 NRC Staff Findings

The NRC staff has determined that OQA Audit M&O-ARP-00-08 was effective in determining the

level of compliance of M&O activities associated with the subject AMRs. The NRC staff agreed

with the audit team conclusion that the OCRWM QA program had been satisfactorily

implemented. The NRC staff also determined the following:

ˇ The NRC staff found the OQA Audit M&O-ARP-00-08 to be thorough, comprehensive,

technically detailed, and professional.

ˇ Specific aspects of the two AMRs and the one CAL audited were found to be technically

insufficient for either the intended purpose or for supporting the stated conclusions. The

specific potential deficiencies are detailed in the sections pertaining to the individual AMRs

and CAL. The DOE audit team Technical Specialists identified these potential deficiencies

and recommendations for improvement and brought them to the attention of the originators,

and the NRC staff concurred with those findings.

ˇ The NRC staff found this audit to be effective in identifying deficiencies and recommending

improvements in the audited documents. However, the DOE OQA should verify that the

recommendations of this audit are satisfactorily addressed by the originators of the AMRs and

the CAL.

4.6.1 Audit Observer Inquiries

There were no audit observer inquires opened during this audit and all previous audit observer

inquiries are closed.