ML20137L465

Discusses Schedule for Level 1 AP600 Pra.Staff Does Not Believe 970610,milestone for PRA Input to FSER Can Be Met

ML20137L465
Person / Time
Site:	05200003
Issue date:	04/03/1997
From:	Martin T NRC (Affiliation Not Assigned)
To:	Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
References
NUDOCS 9704070233
Download: ML20137L465 (3)

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,j*- NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2006H21

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Mr. Nicholas J. Liparulo, Manager l Nuclear Safety and Regulatory Analysis Nuclear and Advanced Technology Division Westinghouse Electric Corporation P.O. Box 355 Pittsburgh, PA 15230

SUBJECT:

SCHEDULE FOR THE LEVEL 1 AP600 PROBABILISTIC RISK ASSESSMENT (PRA)

Dear Mr. Liparulo:

In a letter dated December 6,1996, we sent you a list of potential critical i path issues in the design certification process for the AP600. One of the '

issues (key issue #20) involves integrated use of PRA insights. Subsequent to l this letter the staff has identified additional issues that are impacting the review of the AP600 PRA.

According to the current review schedule, the Level 1 PRA (Chapter 19.1) input to the Final Safety Evaluation Report (FSER) is due to " Projects" by June 10, 1997. This input will include, in addition to the baseline PRA, the staff's evaluations of the " focused" PRA and the risk-based seismic margins analysis.

The staff agreed last December to what they perceived to be a " tight" schedule, proposed by Westinghouse, with the clear understanding that satis-factory responses to all remaining-outstanding issues will be received according to this schedule. However, this did not happen. Two important milestones, a February 28, 1997, deadline for submitting the risk-based seismic margins analysis and the PRA " safety insights," have been either missed or only partially met by Westinghouse. In addition, Westinghouse repeatedly submitted unsatisfactory responses to several outstanding issues.

To finalize the Level 1 PRA input to the FSER, the staff is requesting Westinghouse to pay particular attention to three areas: (1) PRA " safety insights," (2) steam generator tube rupture (SGTR) accident sequence modeling issues, and (3) focused PRA issues.

The first area, i.e., " safety insights," involves a systematic search to identify additional design and operational requirements for the certified design based on PRA insights and assumptions. While PRA " safety insights" for internal events were submitted according to the schedule, Westinghouse missed the milestone for submitting " safety insights" for external events. In addition, the recently submitted list of " safety insights" appears to leave out or redefine many items the staff had brought up during past Nuclear Regulatory Commission / Westinghouse staff meetings. This, if continued, could cause substantial delays in the review because it requires significant reviewer time to interpret PRA results and assumptions.

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6 9704070233 970403 L PDR ADOCK 05200003 A PDR

t Mr. Nicholas J. Liparulo April 3,1997 The second area, i.e., SGTR accident sequence modeling issues, involves the submittal of thermal-hydraulic analyses and related documentation supporting success criteria, time windows for operator actions and otSer assumptions made in modeling SGTR accident sequences. The staff first requested this informa-tion over a year ago but have not yet received satisfactory response. An early resolution of the SGTR accident sequence issues is needed because they could impact both the baseline and focused PRAs as well as the passive system thermal-hydraulic uncertainty issue.

The third area, i.e., focused PRA issues, involves the resolution of several outstanding issues related to the use of PRA results and insights in deciding about an appropriate regulatory tr- iment of non-safety systems (RTNSS).

Such issues were first communicatea to Westinghouse about a year ago with follow-up questions. Furthermore, the staff noticed that in the last revision of the focused PRA, Westinghouse made some imoortant changes in failure data and modeling assumptions which were not adequately explained and properly communicated to the staff. The timely resolution of these issues is necessary to ?llow the staff to finalize the RTNSS input to the FSER according to sc M ule.

For ine reasons explained above, the staff does not believe that the June 10, 1997, milestone for the PRA input to the FSER can be met. A revised schedule will have to be developed with the staff. To avoid further delays, the staff should receive complete and clear responses to requests for additional information, which mostly relates to the three areas outlined in this letter, according to the revised schedule.

If you have any questions regarding this matter, you can contact Joe Sebrosky at (301) 415-1132.

Sincerely, original signed by:

Thomas T. Martin, Director Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-003 cc: See next page DISTRIBUTION:

Docket file PDST R/F SCollins/FMiraglia, 0-12 G18 PUBLIC AThadani TMartin MSlosson TRQuay JSebrosky TKenyon BHuffman DJackson JMoore, 0-15 B18 WDean, 0-17 G21 MPohida, 0-10 E4 ACRS (11) NSaltos, 0-10 E4 GHolahan, 0-8 E2 JFlack, 0-10 E4 MRubin, 0-10 E4 DOCUMENT NAME: A:PRA.PST *See previous concurrence Ts seceive o espy et ente desument,ladeste in the boa: *C' = Copy without ettechment/ enclosure *t* = Copy with attachment / enclosure *N' = No cop 0FFICE PM:PDST:DRPM BC:SCSB:DSSA D:DSSA D:PDST:DRPM D:DSMi NAME JMSebrosky:sg (M) MRubin* GHolahan* TRQuay 19Q TM(rtin DATE 04/ 4 /97 / 03/27/97 04/01/97 04/ L/97 04/3 /97 0FFICIAL RECORD COPY

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". Mr. Nicholas J. Liparulo Docket No.52-003 Westinghouse Electric Corporation AP600

. cc: Mr. B. A. McIntyre- Mr. Ronald Simard, Director Advanced Plant Safety & Licensing Advanced Reactor Programs Westinghouse Electric Corporation Nuclear Energy Institute  ;

4 Energy Systems Business Unit 1776 Eye Street, N.W.

P.O. Box 355 Suite 300 <

! Pittsburgh, PA 15230 Washington, DC 20006-3706 '

Ms. Cindy L. Haag Ms. Lynn Connor Advanced Plant Safety & Licensing Doc-Search Associates Westinghouse Electric Corporation Post Office Box 34 Energy Systems Business Unit Cabin John, MD 20818 i 4

Box 355 Pittsburgh, PA 15230 Mr. James E. Quinn, Projects Manager

LMR and SBWR Programs

• Mr. M. D. Beaumont GE Nuclear Energy Nuclear and Advanced Technology Division 175 Curtner Avenue, M/C 165

_ Westinghouse Electric Corporation San Jose, CA 95125 )

One Montrose Metro  ;

il921 Rockville Pike Mr. Robert H. Buchholz l Suite 350 GE Nuclear Energy l

Rockville, MD 20852 175 Curtner Avenue, MC-781 San Jose, CA 95125 i Mr. Sterling Franks U.S. Department of Energy Barton Z. Cowan, Esq.

NE-50 Eckert Seamans Cherin & Mellott 19901 Germantown Road 600 Grant Street 42nd Floor

Germantown, MD 20874 Pittsburgh, PA 15219

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Mr. S. M. Modro Mr. Ed Rodwell, Manager l Nuclear Systems Analysis Technologies PWR Design Certification 1 Lockheed Idaho Technologies Company Electric Power Research Institute Post Office Box 1625 3412 Hillview Avenue Idaho Falls, ID 83415 Palo Alto, CA 94303

Mr. Frank A. Ross Mr. Charles Thompson, Nuclear Engineer

U.S. Department of Energy, NE-42 AP600 Certification Office of LWR Safety and Technology NE-50

' 19901 Germantown Road 19901 Germantown Road Germantown, MD 20874 Germantown, MD 20874 l

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