ML20247H290
| ML20247H290 | |
| Person / Time | |
|---|---|
| Issue date: | 08/21/1997 |
| From: | Garrick B NRC ADVISORY COMMITTEE ON NUCLEAR WASTE (ACNW) |
| To: | Shirley Ann Jackson, The Chairman NRC COMMISSION (OCM) |
| References | |
| NACNUCLE-S-0090, NACNUCLE-S-90, NUDOCS 9805210122 | |
| Download: ML20247H290 (3) | |
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en ato jog UNITED STATES ACNWS-0090
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ae p, NUCLEAR REGULATORY COMMISSION
- Advisory COMMITTEE oN NUCLEAR WASTE PDR
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August 21, 1997 The Honorable Shirley Ann Jackson Chairman U. S. Nuclear Regulatory Commission Washington, D.C. 20555-0001
SUBJECT:
SUMMARY
REPORT- 93RD MEETING OF THE ADVISORY COMMITTEE ON NUCLEAR WASTE, JULY 23 AND 24,1997, AND OTHER RELATED ACNW ACTIVITIES
Dear Chairman Jackson:
During its 93rd meeting on July 23 and 24,1997 (held at the Southwest Research Institute, Center for Nuclear Waste Regulatory Analyses, Building 189,6220 Culebra Road, San Antonio, Texas), the Advisory Committee on Nuclear Waste (ACNW) discussed the following key issues:
REPORT Report to the Honorable Shirley Ann Jackson, Chairman, NRC, from Dr. B. John Garrick, Chairman, ACNW,
- Comments on the NRC Program To Predict Risk From igneous Activity at the Proposed High-Level Waste Repository at Yucca Mountain, Nevada," August 7,1997.
HIGHLIGHTS OF KEY ISSUES CONSIDERED BY THE COMMITTEE 1
- 1. Performance Assessment Capability in the NRC's Hiah-Level Waste Procram The NRC staff discussed the high-level waste (HLW) performance assessment (PA) program and the capability of the staff to implement this program. One area of focus was the development and implementation of the Total System Performance Assessment (TPA/TSPA) Code, Version 3 (TPA-3). An overview, framework, and schedule of TPA activities were presented, including integration of TPA activities with reviews of the Department of Energy's (DOE's) TSPA results, rulemaking actions, and the development of issue Resolution Status Reports (IRSRs). Staff expertise, resources, and projects to support PA activities, hardware capabilities, and the uses of the Advanced Computer System (ACS)in the Division of Waste Management, Office of Nuclear Material Safety and Safeguards (DWM/NMSS), were discussed. The staff also discussed in detail the TPA-3.1 code architecture and the subsystem abstractions used in the model. The staff described the planned sensitivity studies, including subsystem and overall system sensitivities. One area of application is to develop the relative importance of the issues to be resolved in the IRSRs. The staff also discussed future activities of the program.
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, The Honorable Shirley Ann Jackson 2 Conclusions / Action items:
The Committee will begin to prepare a report to the Commission on PA capabilities in the NRC HWL program at its September 1997 meeting,
- 2. Probabilistic Performance Assessment The Committee held a working group session on the application of probabilistic risk
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analysis methods to PA. Experts in probabilistic risk assessment (PRA) and PA discussed different approaches to the problem. Dr. Stan Kaplan, an expert invited by ACNW, discussed the interpretation of PA results using an event tree approach and identified specific approaches that he believed could be usefulin PA. His presentation covered the use of a matrix approach and Green's functions in the event tree type of analysis. Dr. James Lin, another expert invited by ACNW, discussed the development of top-down event scenarios; he provided the details of developing and applying event trees in PRA. Drs. Robin McGuire and John Kessler, Electric Power Research institute (EPRI), discussed EPRI's PA model, IMARC-3. This model uses a logic tree approach.
They also discussed the model and its application and conclusions for the proposed Yucca Mountain repository. Dr. Robert Andrews, DOE, presented DOE's TSPA model, describing how it is intended to be used in decisionmaking, its conceptual framework, how scenarios are defined, and the model's advantages and disadvantages. Dr. John Helton, Arizona State University, discussed the application of probabilistic methods in the Waste Isolation Pilot Plan (WIPP) PA. His presentation focused on the development and-application of complementary cumulative distribution functions to the WIPP PA. He also discussed the regulatory framework and the analyses needed to demonstrate ;
compliance. Dr. Norman Eisenberg, NRC, discussed the NRC's PA approaches for l waste management. His discussion covered the status of risk-informed, performance-based approaches in DWM, the use of uncertainty analysis, difficulties in applying ]
scenario-based approaches in waste management, and some concepts in applying importance measures in PA. A roundtable discussion followed the presentations.
Conclusions / Actions items:
The Committee will begin to prepare a report to the Commission on probabilistic performance assessment at its September 1997 meeting.
- 3. Tour of the Center for Nuclear Waste Reaulatory Analyses.
On July 25,1997, the Committee toured the Center for Nuclear Waste Regulatory Analyses and observed several ongoing experiments related to the HLW program.
Among the experiments observed were the following:
The long-term pitting corrosion and galvanic corrosion tests - These experiments
! are being conducted under the key technical issue (KTl) on Container Life and l Source Term.
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n The Honorable Shirley Ann Jackson 3 A small-scale thermohydrology experiment - This experiment will investigate the potential for gravity refluxing under conditions of evaporation-condensation, which are expected to prevail initially in the repository. This experiment is being conducted under the KTl on Thermal Effects on Flow.
An analogue model of pull-apart basins, which is a sandbox experiment to investigate the mechanics of faulting -This experiment is being conducted under the KTl on Structural Deformation and Seismicity.
PROPOSED SCHEDULE FOR THE 94TH ACNW MEETING The Committee agreed to consider the following during the 94th ACNW Meeting, September 23 and 25,1997:
Viability Assessment - The Committee will discuss the status of the viability assessment, including design options, TSPA, cost estimates, and schedule. The Committee may also hear an update on the progress of the Preliminary Integrated Safety Assessment.
Enhanced Site Characterization -The Committee will discuss the progress of the enhanced site characterization program, including the status of Cl" sampling and description of the east-west drift. Additional topics may include the Amargosa Valley population survey, waste retrievability, and DOE's interim High-Level Waste Disposal Standard.
Public Comments - The Committee will hear comments from members of the public, representatives of the State of Nevada, affected local counties, and from Native American tribes on concems related to nuclear weste disposal.
Preparation of ACNW Reports -The Committee will discuss proposed reports, including NRC HLW PA, application of probabilistic methods to PA, and approaches to implement multiple barriers and defense in depth in 10 CFR Part 60.
OTHER RELATED ACTMTIES OF THE COMMITTEE The Committee plans to tour the Yucca Mountain site and observe ongoing site characterization activities and experiments on September 24,19g7. l Sincerely, 9
B. John Garrick j Chairman
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