ML20235T021

Comments on NUREG-1150, Reactor Risk Ref Document. Detailed Review Should Be Performed to Assure That Statements Made in NUREG-1150 & Supporting Analyses Have Same Basis

ML20235T021
Person / Time
Site:	Peach Bottom
Issue date:	09/25/1987
From:	Kowalski S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC
Shared Package
ML20235T023	List: ML20235T021 ML20235T068 ML20235T085 ML20235T115 ML20235T139
References
FRN-52FR7950, RTR-NUREG-1150, RTR-NUREG-CR-4550, RTR-NUREG-CR-4696 52FR7950-00027, 52FR7950-27, NUDOCS 8710090232
Download: ML20235T021 (3)

Text

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PHILADELPHIA 2301 M A R K ELECTRIC ET ST R E bbS 5 Cp0 7R NC F'.O. BOX F3699 DRR:A0 % BR PHILADEl.PH! A, PA.1910g N 30 P 1 :08 (215) a41 4 5o 2

5. J. KOW A LSK!

VIC E September 25. 1987

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PRESIDENT Chief, Rules and Procsdures Branch Division of Rules and Records Offico of Administration U.S. Nuclear Regulatory Cannission e.ashington, DC 20555

SUBJECT:

Carments on Draf t NUREG-1150 Reactor Risk Reference Docunent

REFERENCES:

1) Letter, V. S. Boyer to M. L. Ernst, dated September 2, 1986 Coments on Draf t NUREG/CR-4696

2) Letter, V. S. Boyer to W, M. Morris, dated September 19, 1986

! Carments on Peach Bottom Containment Event Tree

3) Letter, S. J. Kowalski to W. M. Morris,

, dated January 26, 1987 Corments on Draf t NUREG/CR-4550, Volume 3

9) Letter,, R. F. Janecek (BWROG) to NRC, j dated August 21, 1987 Co,ments on NUREG-1150 i The PhlNduphia Electric Company (PECo) appreciates the opportunity tr cryment. on the subject document. The opportunity to  !

work with your contracter personnel during preparation of supporting l

documentation for NUREG-1150 has been beneficial for us in  ;

understanding the current issues and risks calculated for PECo's Peach Bottom Atav.*c Paa r S t.at ion. You were unable to incorporate most of our carments on orly draft reports (References 1, 2, S 3) due to schedule restraints.. We therefore include them by reference as NUREG 1150 comnents.

PECo participated in development of the BWROG conments on NUREG-1150 (Reference 4) and supports the conments therein.

Use of risk assessment as a logical f ranym.-k for regulatory decision making and examination of safety issues represents a step forward in the regulation process. However supporting probabilistic and phenonenological analyses contain sone extremely conservative assumptions and uncertainties that affect the perception of risk as appl 1ed to BWRs, specifIcal1y Peach Bottom.

I 8710090232 NUREG 870925 l PDR PDR l

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i Assumptions made because of uncertainty in phenomena or insufficient data drive the calculated risk at Peach Botton in the current draft. Camon cause battery failure for example is a significant contributor to the total core danege frequency and has been asserted to exist without the necessary technical support. We believe that the analysis does not reflect our surveillance testing program and separation of the batteries between the two, generating-units. Reference 3) provides PECo comnents on battery failure and station blackout in general for the Peach bottom analysis,. >

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The polling of experts to define or bound the uncoctainty of..

phenomena not calculated or mechanistically nodeled is a valid approach. The expert opinion process has a significant impact on the l

risk results.. In this regard the results are highly dependont on the process used to select the experts and the nethod of solicitation of. ,

their opinions. In order to produce unblased results, a saapilng 94a l

representative population of experts is required and their opinions l solicited in a nenner which provides technically-accurate results.

Based on the expert review group composition, it is not clear that they represent an unbiased cross-section of the current severe accident community. It would be appropriate to recognize industry experts outside those in the national laboratories and repo11 the

" expert group" prior to the final NUREG-1150 report.

The analysis of external events at Peach Bottom will provide a ,

nore conplete picture of the risks associated with operation of a nuclear facility. External events wly,have an impact on the results of current analyses described Ire NUREG-1150 and should have PECo and pubile review prior to the final g<hlication of NUREG-1150. As evidenced by the references and Infornal contacts with your contractors, PECo is interested Ir. eisuring realistic and accurapa l modeling of Peach Bottom.

Caution should be exercised when applying the insights or results of NUREG-1150. As indicated many times in the report, significant contributors to core danage frequency as well as the l uncertainty range of the reference plants limit the applicabilltv e.f l the study to other plants.

Discontinultles exist between statenents nede in the neln report and those found in the Appendices and supporting doctnentation. A 1 detailed review should be perforned to assure that the statenents nede  !

In NUREG-1150 and the supporting anal 43es have the sane basis.

The results of the NUREG-1150 studies nust be carefully and clearly presented in the main report in order to prevent mistndetotanding by the general pubile such as that which occurred with the draf t docunent.

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Our experience and continued interaction with your contractors u Indicates we are all interested in a doctment of high technical quality-whic'n accurately characterizes reactor risk. More realistic analysis will help to attain this goal and make the supporting NUREG-1150

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analyses more useful for decision making.

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Very truly yours,

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l GAK/cb/09168704 Attachments Copy to: V. Stello - NRC F. Eltawila - NRC J. Murphy - NRC a- W. Russell - NRC (Region I) g 1

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