ML20034H541
| ML20034H541 | |
| Person / Time | |
|---|---|
| Issue date: | 03/10/1993 |
| From: | Russell W, Speis T Office of Nuclear Reactor Regulation, NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Beckjord E, Murley T Office of Nuclear Reactor Regulation, NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| References | |
| NUDOCS 9303180269 | |
| Download: ML20034H541 (7) | |
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/ga"%g"'h, UNITED STATES M
.E NUCLEAR REGULATORY COMMISSION 8
WASHINGTON, D.C. 20556 s...../
I MAR 10 IM i
HEMORANDUM FOR:
Thomas E. Murley, Director Office of Nuclear Reactor Regulation Eric S. Beckjord, Director Office of Nuclear Regulatory Research FROM:
William T. Russell, Associate Director for Inspection and Technical Assessment Office of Nuclear Reactor Regulation Themis P. Speis, Deputy Director for Research Office of Nuclear Regulatory Research
SUBJECT:
STEAM GENERATOR VOLTAGE BASED INTERIM PLUGGING CRITERIA TASK GROUP PROPOSAL The purpose of this memorandum is to propose establishing a task group to review the technical bases for and make recomendations on the acceptability of voltage based steam generator tube interim plugging criteria (IPC). The main objectives of the task group will be to resolve outstanding issues regarding voltage based IPC and provide conclusions and recommendations to support reviews of licensee proposals to implement voltage based plugging criteria. The task group will utilize the methodology, as appropriate, which was developed by RES and discussed in the memorandum from E. S. Beckjord to T. E. Murley, " Interim Plugging Criteria for Trojan Nuclear Plant," dated January 15, 1993. RES staff who developed various aspects of the methodology will participate in the task group activities and IPC review as required. The charter and action plan for the task group were developed by representatives from NRR and RES and these offices will jointly support the Task Group activities.
The attachment provides the charter, organization and action plan for the Task Group. The-Task Group includes representatives and contractors from NRR and RES. NRR will have the lead role and will provide the bulk of the Task Group effort.
RES will review the positions on the voltage based interim plugging i
criteria and support the Task Group activities to the extent necessary to accomplish the goals set forth in the group's charter. Contractor support will be provided by RES, and the contractors will take direction from the RES program manager. The membership of the Task Group has been selected with the intent of assuring that all outstanding issues are identified and that objective, technically sound conclusions and recommendations are developed.
Staff resources are expected to be on the order of 15 FTE-months for this task group effort.
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m V;;; i @t The task group will have until March 31, 1993 to perform its review and prepare its conclusions and recomendations. The product of-the Task' Group will be a report sumarizing the results and conclusions of _the. Task Group and a package for presentation to the CRGR. ORGMAL s!OTED BY W. T. RUCSELL 3 William T. Russell, Associate Director - for Inspection and Technical Assessment Office of Nuclear Reactor Regulation =i ORIGINALSIGNED BY: Themis P. Speis, Deputy Director Office of Nuclear Regulatory Research
Enclosure:
DISTRIBUTION: As Stated EMCB RF Central Files DE RF~. WRussell cc: Task Group members -JSeveswWee AThadani-LShao-WMinners TSpeis NRC:PDR.
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I Ill 1 [s1. l ORGANIZATION -l CO-CHAIRPERSONS I Jack R. Strosnider, Jr. Richard M. Lobel Materials & Chemical Engineering Containment Systems and Severe Branch, NRR Accident Branch, NRR q MEMBERS .i NRC STAFF CONTRACTORS Materials /NDE: E. Murohv (NRR/EMCB) R. Kurtz (PNL) .l J. Muscara* (RES/MEB) P. Heasier (PNL) E.-Hackett (NRR/ENCB)- C. Dodd (ORNL) (L. Abramson)* (RES/PRAB) T. Kassner (ANL) (C. Sernan)* (RES/MEB) (approximately $80K will be~ necessary; l for contractor support] a Risk Assessment: S. Lona (NRR/SPSB) A. Buslik* (RES/PRAB) Systems: R. Landry (NRR/SPSB) l C. Liana (NRR/SRXB) L. Shotkin* (RES/DSR)- Radiological: K. Eccleston-(NRR/PRPB) J. Honenfeld* (RES/RPSIB) Severe Accident: _ W. Lono (NRR/SCSB)' y Projects: T. Reed (NRR/PDII-3)
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VOLTAGE BASED IPC TASK GROUP -i CHARTER ) Review the technical bases and outstanding issues related to voltage-l based interim plugging criteria for outside diameter stress corrosion cracking at tube support. plate' intersections and prepare conclusions and recommendations including the technical basis, for~ presentation to the CRGR,; on implementation of voltage based interim plugging criteria. _a e.
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.3-, , f -; 4 STEAM GENERATOR VOLTAGE BASED IPC STUDY GROUP ACTION PLAN 1.-ASSESS INSPECTION METNtes/ SCOPE \\ . 11. ASSESS Mein 0DS FOR DETERNINING \\ DE WADATIEnf RATES \\ \\ \\ N VI. PREPARE CONCLUSIONS A W - Ill. ASSESS MARGINS AGAINST TUDE RUPTURE N\\ RECCISEWATIONS ON ~ 1\\ MATERIALS ISSUES IV. ASSESS LFAK RATE N0DELS -\\ / \\ / V. ASSESS TUGE RUPTURE AW / XI. PREPARE FINAL REPORT A W LEAK RATES / PROS / \\ CRGR PACKAGE l i Vll. ASSESS ADEcuACY OF kWST INVENTORY .f \\ I N I' Vill. ASSESS RADIOLOGICAL CONSEQUENCES \\ ' X. PREPARE CONCLUSIONS AND -\\ REccleEENDATIONS ON SYSTEMS,- f- '% N' RAD PROTECTION AND RISK ISSUES IX. ASSESS RISE' f f %-tmwm 4W " * * * * *p-*t W*s'6 e-h n,*st we89'g
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? g STEAM GENERATOR VOLTAGE BASED IPC STUDY GROUP ACTION PLAN f TASK I: ASSESS INSPECTION METHODS / SCOPE The objective of this task is to evaluate' the adequacy of the inspection methods, scope of-inspection and inspection program implementation. Issues. regarding the capability and reliability of bobbin coil and rotating pancake coil examinations to characterize outside diameter stress corrosion cracking at the tube support plate intersections will be evaluated. l TASK II:-ASSESS METHOD FOR DETERMINING DEGRADATION RATES The objective of this task is to determine the adequacy of. the method used to determine the rate of degradation and expected distribution of defects at the end of a cycle of operation. Differences in the industry model which uses Monte Carlo methods to predict changes'in defect voltage distributions and other models for predicting defect growth during the operating cycle will be assessed. TASK III: ASSESS LEAK RATE MODEL The objective of this task is to assess the models used for predicting leak rates from a single tube. The industry's model which uses a voltage verses leak rate correlation and other models for predicting the leakage from a-degraded tube will be evaluated. TASK IV: ASSESS MARGINS AGAINST TUBE RUPTURE The objective of this task is to assess the models used for evaluating the margins against tube failure. The industry's model which uses voltage verses burst pressure correlations and other models will be assessed. TASK V: ASSESS POTENTIAL FOR TUBE RUPTURE AEl LEAK RATES / PROBABILITIES The objective of this task is to use the conclusions from Tasks I through IV to assess the margins against tube rupture and the predicted primary-to-secondary leak rates and associated probabilities. The propagation of ' uncertainties and conservatism through the evaluation will be assessed. This task will result in conclusions regarding the margins against tube rupture compared to R.G. 1.121 and the predicted leak rates and their associated-uncertainties'.. Probabilities of tube rupture and primary-to-secondary leakage i will be assessed. j 1 TASK VI: PREPARE CONCLUSIONS AND RECOMMENDATIONS ON MATERIALS ISSUES NRR will identify'open issues and develop draft positions on the areas addressed in Tasks I-V. The draft positions will be reviewed by RES-and RES contractors, and conclusions-and recommendations related to inservice inspection, tube integrity and leak rate issues will be documented for input to the final report.
i q ~ n VU o TASK VII: ASSESSNENT OF ADEQUACY OF.RWST INVENTORY Calculations will be done for a postulated steamline break with an assumed large primary-to-secondary steam generator leakage to evaluate the ability to shutdown and bring the plant to a cooled and depressurized condition before the burated water supply in the RWST is exhausted. This calculation will only exhibit the capability of the emergency operating procedures to bring the plant to a safe condition and therefore_ avoid core damage. It will not be used for compliance to the limits of Part 100. TASK VIII: ASSESS RADIOLOGICAL CONSEQUENCES A series of off-site dose calculations will be done-as a sensitivity study on PWR primary to secondary side leakage coincident with a steam generator depressurization. These calculations will be done using the standard SRP assumptions and criteria and with sone carefully selected and justified. calculations using more realistic assumptiens. The results of these calculations will be used to assess radiological consequence of increasing primary to secondary leakage. TASK IX: ASSESS RISK ~ In order to put the Interim Plugging Criteria into a safety perspective, an estimate will be made of the overall risk, expressed as the frequency of a large release. This will be done by preparation of a limited risk assessment and the use of information from other risk studies. l TASK X: PREPARE CONCLUSIONS AND RECONNENDATIONS ON SYSTENS, RADIATION PR0TECTION AM RISK ISSUES Conclusions and recommendations resulting from the assessments in Tasks.VII through IX of issues related to systems response, radiological consequences and risk will be documented for input to the final report. TASK XI: PREPARE FINAL REPORT AND CRGR PACKAGE NRR, with input from the contractors, will prepare a report providing their I conclusions and recommendations regarding voltage based interim plugging - criteria. The report will provide an assessment of issues that have been raised regarding voltage based plugging criteria and recommendations on the use of voltage based interim plugging criteria. Future activities for the industry and the NRC will also be recommended. A package' including a limited regulatory impact study will be proposed for presentation to the CRGR. -}}