ML19331C686

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Responds to NRC 800310 Ltr Requesting Info Re Auxiliary Feedwater Sys.Sys Has Been Reviewed & Found to Meet Requirements of SRP 10.4.9 & Branch Technical Position ASB-10-1.Two Repts Encl
ML19331C686
Person / Time
Site: Mcguire, McGuire  Duke Energy icon.png
Issue date: 08/13/1980
From: Parker W
DUKE POWER CO.
To: Harold Denton, Youngblood B
Office of Nuclear Reactor Regulation
Shared Package
ML19331C687 List:
References
NUDOCS 8008190384
Download: ML19331C686 (2)


Text

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DUKE POWER COMPANY Powzu Derimswo 422 Socru Cuuacu Srnzer, CnAar.orre, N. C.ae24a WILU AM Q. PAM R CR, J R. August 13, 1980

'/icr Pets.ctee? TELtPwCmt:4 ta 704 Seta= Peoowcmo= 373.ac es Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission .

Washington, D. C. 20555 Attention: Mr. B. J. Youngblood, Chief Licensing Projects Branch No. 1 Re: McGuire Nuclear Station Docket No. 50-369, -370

Dear Mr. Denton:

By a letter dated March 10, 1980, Mr. D. F. Ross, Jr. of your Staff requested information related to the Auxiliary Feedwater System (AFWS) for McGuire Nuclear Station Units 1 and 2. Our response to your questions is provided as follows:

(a) The Auxiliary Feedwater System has been reviewed and found to meet all the requirements of Standard R'eview Plan 10.4.9 and 3 ranch Technical Position ASB-10-1.

(b) A reliability evaluation based on the method described in Enclosure 1 to your letter has been performed. Twenty copies are enclosed for your review. This document is entitled WCAP-9751, " Reliability Analysis of the Auxiliary Feedwater System for the McGuire Nuclear Station." The evaluation was designed to determine the dominant contributors to system unavailability; to establish if component dependencies exist; and to allow a reliability comparison to other studied AFWS.

The report concluded that the McGuire AFWS has power diversity in that both electrical motor-driven and steam turbine-driven pumps are used to provide auxiliary feedwater flow during a plant accident. The analysis conducted revealed no location dependencies which could cause common mode failure between the two types of pump systems employed. In addition, no common dependencies in auxilidry support equipment, including AC and DC power sources, were identified cs possible centributors to ec= mon mode failure for s'; stem operation.

8008190 M f

Mr. Harold R. Denton, Director August 13, 1980 Page Two In regard to reliability, the report concludes that the AFWS of the McGuire units as presently designed, when compared to other AFWS designs for Westinghouse NSSS as analy 2d by the NRC, is of a medium rank, as defined in NUREG-0611, for a loss of main feedwater with the reactor trip transient; of a low rank (high end) for loss of main feedwater coupled with a loss of offsite power; and of a medium rank (high end) for the unlikely transient of a loss of main feedwater in coincidence with a loss of both onsite and offsite AC power.

The analysis verified, for two of the transients studied, that the McGuire AFWS as presently design,d does indeed meet the single-failure criteria presently required of a safety system in the NRC's licensing of a nuclear power plant. The other transient case studied dealt with reliability evaluation of the AFWS considering multiple failures in its AC power sources.

(c) A review was conducted by Duke Power Company of the Westinghouse evalua-tion descr: bed above. It was determined that no changes are required in the AFWS des!.gn for McGuire Nuclear Station.

(d) Responses to the questions identified in Enclosure 2 of your letter are attached for your review.

Ple e advise if yo have any questions on this matter.

V y truly yours h-w.- /.3. -

William O. Psrker, Jr LJB:scs Attachments J

DUKE POWER COMPANY MCGUIRE NUCLEAR STATION ^

UNITS 1 AND 2 ATTACHMENT 1 WCAP-9751, " Reliability Analysis of the Auxiliary Feedwater System for the McGuire Nuclear Station"

^

July, 1980 i

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