ML20052A090

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Summary of 820211-12 Meetings W/Util,Ge,Sai & Nusa Re Probabilistic Risk Assessment.Viewgraphs Encl
ML20052A090
Person / Time
Site: Limerick  
Issue date: 03/23/1982
From: Abelson H
Office of Nuclear Reactor Regulation
To:
Office of Nuclear Reactor Regulation
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ML20052A091 List:
References
NUDOCS 8204270068
Download: ML20052A090 (9)
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MAR 2 3 1982

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FACILITY:

Limerick Generating Station SU3 JECT:

SUMMARY

OF February 11-12, 1982 MEETING On February 11 and 12 a meeting was held at Brookhaven National Laboratory to discuss the Probabilistic Risk Assessment (PRA) for the Limerick Generating Station. The objective of the discussion was to clarify the methods and assumptions employed in the PRA.

Participants included NRC and its technical review contractor CHL, and PECO and its contractors Bechtel, General Electric, SAI, and NUS.

The meeting was open to observers from the public. A list of attendees is provided in Enclosure 1.

The meeting consisted of a series of formal presentations by PECO and its contractors and discussion / comment periods. The agenda with a list of presenting organizations is provided in Enclosure 2.

Copies of the visual aids used in the presentations are found in Enclosure 3.

However, proprietary material relating to fault trees, discussed during the afternoon session of February 11, 1982, is not included here. Highlights of the presentations are summarized below:

PEC0's introductory comments included their definition of the PRA scope, the roles of PECO's contractors in preparation of the PRA, and a history of events leading to preparation of the PRA.

PECO and GE presented an overview of the study including the tasks performed, accident initiators selected, generic accident sequences, and major results of the study.

PECO presented the general layout of Limerick, the configuration of a BWR-4/MKII, and a summary of PRA related systems.

The presentation o n accident sequence definition included success criteria for various initiators; release sources, core condition, containment condition, coolant inventory and other conditions resulting from different accident sequences, and; core damage frequencies for different sequences with a comparison to WASH-1400.

The discussion on quantitative treatment of dependencies included enyironmental degradation of equipment, maintenance, instrumentation miscalibration, and various system interfaces.

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{qw v The discussion of Technical Specifications pointed out their important role in treating system dependencies during maintenance.

Peach Bottom Tech. Specs. were employed in the PRA since those for Limerick are not yet available.

The discussion of common-mode failures included functional dependencies between systems involved in accident sequences; consideration of some human interfaces, test and maintenance interfaces, and; common hardware in fault-tree construction.

The discussion of fault tree level of detail covered valves, pumps, turbines, sensor!. switches, and other components. The HPCI fault tree was presented as an example.

A detailed discussion of three accident sequences was presented.

These were; turbine trip with inadequate coolant make-up; MSIV closure coupled with a long-term power conversion system problem; MSIV closure wf th subsequent failure to scram.

  • The discussion on system unavailabiltiy included fault-tree input data l

sources. The HPCI system was discussed as an example and comparisons l

with WASH-1400 and operating experience data were provided.

The presentat. ion on human error probabilities provided the following computational bases; GE/BWR emergency guidelines for operator response; need for operator initiation of failed automatic systems; high stress environment.

The discussion of uncertainties pointed out that a Monte Carlo simulation was used to generate uncertainties for dominant sequence probabilities and that Complementary Cumulative Distribution Function (CCDF) uncertainties include uncertainties in sequence evaluations, in-core release processes, and explant consequence calculations.

Bechtel's presentation of the Mark II containment analysis addressed containment response due to varying pressures resulting from core melt accidents and included responses of the refueling head, hatches, and pressure boundary valves.

It was concluded that no valves would fail below 300 psig, the limiting contain-ent pressure (for failure) was 140 psig, and that failure would be initiated by a vertical crack at wetwell midheight.

The presentation on core melt phenomena included computational codes used; times, paths, quantities, and species of release; decontamination sources and factors assumed.

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The presentation on explant consequences included a discussion of inputs to the CRAC computational code.

Included were site-specific topological, meteorological, and demographic data, evacuation rates, and use of a threshold model for early fatalities.

The presentation comparing the Limerick PRA with the WASH-1400 study outlined the computational cases considered and addressed differences in site, plant design, data, and methodology.

Comparisons indicated that the Limerick site posed a greater risk while the Limerick plant design posed less of a risk.

The overall net effect in PEC0's analysis was that Limerick posed a lower risk than the WASH-1400 baseline.

Following the final presentation on February 12, 1982, a general question /

comment period was held involving all participants. With regard to action items, NRC requested that PECO provide a time estimate for submittal of the following:

1.

Further data on design features such as ATWS Alternate-3A and the Containment Over-pressure Relief System which have been assumed in the PRA and contribute to a large reduction in overall risk.

2.

GE maintenance data used'in the PRA.

3.

Input data used in the CPAC computational code.

In connection with this, reference was made to the letter of January 18, 1982 from A. Schwencer of NRC to E. Bauer of PECO, requesting that PEC0 furnish NRC, on a continuing basis, with data on design and/or operational changes that may significantly affect the PRA.

With regard to schedule, the milestones and dates reflected in the latest PRA review schedule were presented by NRC.

NRC stated that the PRA evaluation would be documented in a NUREG to be issued 11/30/82.

This report would include an assessment of the methodology used and definition of the dominant accident sequences with corresponding risks.

The meeting adjourned around noon on February 12, 1982.

Note that an opportunity for comments from members of the public was provided at the close of the morning session on February 11.

Comments were offered by Alan Nogee, a staff member of the Keystone Alliance, a petitioner for intervention in the Limerick proceeding, also acting as respresentative of petitioner Limerick Ecplogy Action. Mr. Nogee's comrnents are sumarized in Enclosure 4.

WW Harvey Abelson, Project Manager Licensing Branch No. 2 Division of Licensing h/

E. Chelliah Reliability & Risk Assessment Branch h

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Nr. Edward G. Bauer,. Jr.

Vice President &' General Counsel Philadelphia Electric Company 2301 Market Street Philadelphia, Pennsylvania 19101 cc: Troy B. Conner, Jr., Esquire Charl'es W, Elliott, Esquire Conner & Wetterhahn Thomas & Hair 1747 Pennsylvania Avenue, NW 123 North Fifth Street Washington, D.C.

20006 Allentown, PA 18102 Mr. Robert W. Adler Judith A..Dorsey, tsquire Assistant Counsel Limerick Ecology Action Commonwealth of Pennsylvania, DER 1315 Walnut Street, Suite 1632 505 Executive House Philadelphia, PA.19107 P.O. Box 2357 Harrisburg, PA 17120 Mr. Karl Abraham Public Affa. irs Officer Honorable Lawrence Coughlin Region I House of Representatives U.S. Nuclear Regulatory Commission Congress of the Uni.ted States 631 Park Avenue Washington, D.C.

20515 King of Prussia, PA 19806 Roger B. Reynolds, Jr., Esquire Mr. Jacque Durr 324 Swede Street Re's7denf ' Inspector Norristown, PA 19401 U.S. Nuclear Regulatory Commission P.O. Box 47 Joseph A. Smyth Sanatoga, PA 19464 Assistant County Solicitor County of-Montgomery James M. Neill, Esquire Courthouse Associate Counsel for Del-Aware Norristown, PA 19404 Box 511 Dublin, PA 18917 Eugene J. Bradley Philadelphia Electric Company Joseph H. White III Associate General Counsel 11 South Merion Avenue 2301 Market Stree.t Bryn Mawr, PA 19010 Philadelphia, PA 19101 Dr. Judith H. Johnsrud Mr. Vincent Boyer Co-Director Senior Vice President Environmental Coalition on Nuclear Operations Nuclear Power Philadel::hia Electric Company 433 Orlando Avenue 2301 Market Street State College, PA 16801 Philadelphia, PA 19101 Thomas Gerusky, Director Mr. Marvin I. Lewis Bureau of Radiation Protection 6504 Bradford Terrace Dept. of Environmental Resources Philadel phia, PA 19149 Sth Floor, Fulton Bank Bldg.

Third & Locust Streets -

Frank R. Romano, Chairman Harrisburg, PA 17120 Air & Water Pollution Patrol 61 Forest Avenue Director, Pennsylvania Emergency Ambler, PA 19002 Management Agency Basement, Transportation &

Safety Building Harrisburg, PA 17120 o

John Shniper Lawrence Brenner, Esq., Chairman

  • Meeting House Law Bldg. & Gallery Administrative Judge Mennonite Church Road -

U.S. Nuclear Regulatory Commission Schuylkill Road (Rt. 724)

Washington, D.C.

20555 Spring City, PA 19475

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Dr. Richard F. Cole

20555 103 Vernon Lane, Box 186 Moylan, PA 19065 Dr. Peter A. Morris

  • Administrative Judge Alan J. Nogee U.S. Nuclear Regulatory Commission The Keystone Alliance Washington, D.C.

20555 3700 Chestnut. Street Philadelphia, PA 19104 W. Wilson Goode Managing Director City of Philadelphia Philadelphia, PA 19107

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? William A. Lochstet 113 E. Aaron Drive State College, PA 16801 Walter W. Cohen Consumer Advocate Office of Attorney General 1425 Strawberry Square Harrisburg, PA 17120 Steven P. Hershey, Esquire Consumers' Education & Protective Association Sylvania House Juniper & l.ocust Streets Philadelphia, PA 19',07 Sugarman & Denworth Sui te ' 510 North American Building 121 South Broad Street Philadelphia, PA 19107 Donald S. Bronstein, Esquire The National Lawyers Guild Third Floor 1425 Walnut Street Philadelphia, PA 19,102

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MEETING

SUMMARY

DISTRIBUTION

,'%R 2 3 1982

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ll,.. Docket:

File' k W. Gammill NRC PDR W. Minners L PDR F. Schroeder NSIC D. Skovholt TERA M. Ernst TIC L. Hulman 0I&E C. Berlinger ACRS (16)

K. Kniel G. Knighton LB#2 File A. Thadani H. Denton/E. Ca2e J. Kramer D. Eisenhut/R. Purple D. Ziemann A. Schwencer Region 23:

B.J. Youngblood Resident Inspector F. Miraglia E. Adensam NRC

Participants:

J.R. Miller A. Thadani G. Lainas F. Coffman R. Vollmer E. S. Chell f ah J.P. Knight H. Abelson R. Bosnak S. Lewis F. Schauer A. Schwencer R.E. Jackson Project Manager H. Abelson Attorney, OELD EHyl ton R. Tedesco G. Lear S. Pawlicki V. Benaroya Z. Rosztoczy bec: Applicant Service List W. Haass D. Muller R. Ballard W. Regan R. Mattson F. Congel

0. Parr F. Rosa

.. Butler W

R. Houston M. Srinivasan L. Rubenstein T. Speis W. Johnston J. Stolz S. Hanauer e

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ENCLOSURE 1 LIST OF ATTENDEES NAME AFFILIATION A. Thadani NRC F. Coffman NRC E. S. Chell f ah NRC H. Abelson NRC S. Lewis NRC A. Schwencer NRC T. Shannon PECO J. Doering PEC0 G. S. Edwards PECO R. H. Logue PECO C. H. Rush PEC0 R. L. Harper PEC0 R. A. Hulford PECO S. Levine NUS E. R. Schmidt NUS E. T. Burns SAI A. Unione SAI L. G. Frederick GE N. J. Tuholski BECHTEL M. J. Wetterhahn C&W I. A. Papazoglou BNL L. Lederman BNL R. A. Bari BNL W. Y. Kato BNL K. K. Shiu BNL R. Karol BNL R. E. Hall BNL S. Fiarman BNL H. Ludewig BNL A. Busiik BNL D. Diamond BNL C. Economos BNL H. Hwang BNL W. T. Pratt BNL A. Tingle BNL J. Tingle none (Public)

A. J. Nogee Keystone Alliance (Public)

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ENCLOSURE 2 AGENDA ITEM PRESENTED BY February 11, 1982 - Morning Session 1.

Introduction & Backgound PEC0 2.

Overview of the Study and Main Results PEC0/GE 3.

Plant Layout PECO 4

Overview of Selected Safety Related Systems PECO

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February 11, 1982 - Afternoon' Session 6.

Definition of Accident Sequences sal 7.

Treatment of Dependencies SAI 8.

Role of Technical Specifications PEC0/SAI/GE 9.

Treatment of Common-mode Failures SAI 10.

Level of Detail in Fault Trees SAI 11.

Discussion of Selected Accident Sequences SAI

12. System Unavailabilities PEC0/SAI 13.

Treatment of Human Error Probabilities SAI

14. Uncertainties PEC0/SAI February 12, 1982 - Morning Session 15.

Evaluation of Primary Containnent BECHTEL/SAI

16. Core Melt Phenomena SAI 17.

Explant Consequences SAI

18. Sensitivity Analysis SAI
19. Comparison with WASH-1400 BWR PEC0/GE 20.

General Discussion All Participants i

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DESIGUATED ORIGIIIAL

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