ML20078S766

Clarifies Margins Analysis Results Previously Performed on Masonry Wall,Identified in 940114 TS Change Request 93-18-0 as Outlier. Analysis Corroborates Results of NEDC-31858P Seismic Methodology Provided in Subj TS Change Request

ML20078S766
Person / Time
Site:	Limerick
Issue date:	12/22/1994
From:	Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9412290200
Download: ML20078S766 (3)

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station sugport Deptstrnsnt "4 4 YECO ENERGY ee= ~ c-Nuclear Group Headquarted 965 Chesterbrook Doulevard Wayne, PA 19087-5691 I

i December 22,1994

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Docket Nos. 50-352 50-353 License Nos. NPF-39 NPF-85 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

SUBJECT:

Umerick Generating Station, Units 1 and 2 Technical Specifications Change Request No. 93-18-0 MSIV Leakage Control System Gentlemen I

By letter dated January 14,1994, PECO Energy Company (PECO Energy) submitted a Limerick Generating Station (LGS), Unit 1 and Unit 2 Technical Specification (TS) Change Request (i.e.,93-184) that proposed to increase the allowable leak rate for the main steam isolation valves (MSIVs) and to delete the MSIV Leakage Control System. The Change Request utlized the General Electric, Boring Water Reactor Owner's Group (BWROG) seismic verification methodology (NEDC 31858P). The NRC requested additional information pertaining to this methodology, and it was provkfed by PECO Energy letters dated August 1,1994, October 25, 1994, and December 13,1994.

On December 19,1994, a telephone conversation between the NRC and PECO Energy was established to clarify additional seismic structural issues pertaining to an analysis performed on a masonry wall, identified as an " outlier" in the January 14,1994, PECO Change Request.

During the December 19,1994, telephone conversation, PECO agreed to supply information to  ;

, the NRC, which wHI not be part of the LGS licensing design basis, but which wRI corroborate the i results of the NEDC 31858P seismic methodology provided in the January 14,1994, change request submittal. Therefore, the following is the information requested by the NRC, which wRI  ;

j clarify the margins analysis results previously performed.

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l PECO has performed a seismic margins evaluation of the 'outiler" masonry wall following the guidance provided in EPRl/NP-6041. This evaluation concludes a High Confidence of a Low I'robability of Failure (HCLPF) substantially above the plant Safe Shutdown Earthquake (SSE)

level of 0.15g. The ultimate moment capacity of the wall is calculated as part of this evaluation.

The value of nine-tenths of the ultimate moment capacity is calculated to be 1107 lb-infin. As l

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. December '22,1994 Pag'e 2 requested by the NRC In the December 19,1994, telephone conversation, the seismic moment demand i consistent with the elastic response of the wall was also calculated. The selsmic demand is based on a NUREG/CR-0098 median spectral shape anchored to the plant SSE 0.15g peak ground acceleration. In-structu.e spectra are developed by scaling of existing Turbine Building spectra and are the average of the upper and lower support elevation scaled spectra. This moment demand has been determined by assuming that the wall behaves as a simply supported uniformly loaded beam. The moment demand determined by this procedure is 854 lb-in/in. This one-time confirmatory analysis demonstrates that the masonry wall's capacity exceeds the calculated demand at the SSE level.

This analysis corroborates the results of the NEDC 31858P seismic rrethodology provided in the January 1

14,1994, change request submittal which documented that the masonry wall will be capable of performing its function during and after an SSE.

If you have any questions, please do not hesitate to contact us.

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Very truly yours,

. . Os G. A. Hunger, Jr.,"

Director-Licensing Enclosure l

, cc: T. T. Martin, Administrator, Region I, USNRC (w/ enclosure) i N. S. Perry, USNRC Senior Resident inspector, LGS (w/ enclosure)

! R. R. Janati, PA Bureau of Radiological Protection (w/ enclosure) 1 l

1 l

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... =

l Cd'MMONWEALTH OF PENNSYLVANIA  :

ss.

COUNTY OF CHESTER  :

l W. H. Smith, Ill, being first duly swom, deposes and says: That he is Vice President of PECO Energy Company, the Applicant herein; that he has read the enclosed Information supporting Technical Specifications Change Request No. 9318-0 " Increase the Allowable Leak Rate for the Main Steam 1

Isolation Valves and Delete the MSIV Leakage Control System,* for Umerick Generating Station, Unit 1 f

and Unit 2, Facility Operating License Nos. NPF-39 and NPF-85, and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, l Information and belief.

4, . /

Vice President Subscribed and swom to before me this dl4 day of f A 1994.

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Erics A.Sarefcary Pttic Trer:n Twp,Chester Ccurty My Cccescon Expres July 10.1995

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