ML20087G021

Updated RO 370/83-57:shutdown Capability Never Jeopardized & Unit Could Be Shut Down Given Fire in Annulus W/Sprinker Isolation Valve Closed.Cause Unknown.Figure Illustrating Cable Separation Encl

ML20087G021
Person / Time
Site:	Mcguire
Issue date:	03/07/1984
From:	Tucker H DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
RO-370-83-57, NUDOCS 8403190303
Download: ML20087G021 (3)

Text

g DUKE POWER GOMPANY P.O. DOX 33180 CIIAMLOTTE, N.C. 20242 HALH. TUCKER Tearraioxe

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N MAR 15 A 8 : 3P'h7'1984 Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street NW, Suite 2900 Atlanta, Gecrgia 30303

Subject:

McGuire Nuclear Station Unit 2 Docket No. 50-370 LER/R0-370/83-57

Dear Mr. O'Reilly:

The following is additional information relating to Reportable Occurrence Report R0-370/83-57 which was submittel by my letter dated October 26, 1983 and subst-quently revised by my letter of January 16, 1984. The submitted report is still applicable. This additional information is provided in response to a February 16, 1984 request by Messrs. V. Brownlee and T. Conlon of your staff.

The Annulus Sprinklcr tyctem is provided to meet requirements of 10 CFR 50 Appen-dix R,Section III.G.2.e. During the time the Annu]us Fire Protection System valve (lRF-989) was shut the Annulus Sprinkler System was out of service and there-fore the plant was in non-compliance with Appendix R. Messrs. Brownlee and Cenlon's concern was that with the plant in non-compliance with Appendix R, it would not have been able to demonstrate shutdown capability; i.e. could the unit have been brought to hot shutdown and subsequently to cold shutdown with a fire in the Annulus and the Annulus Sprinkler System isolated (lRF-989 closed).

At no time was shutdown capability jeopardized, the unit could be shutdown given a fire in the Annulus with the sprinkler ieolation valve closed. This is based on several factors:

e low combustible loading in the Annulus; the fire initiating event would be an exposure fire from transient combustibles which is a low probability event e Growth of fire involvlag plastic insulation is very slow e Detection is provided in areas where cables are located e Upon detection the fire brigade would respond e Redundant functions required for shutdown are reasonably well separat-ed and a fire would not be expected to propagate significant distances throughout the Annulus before suppression activities would bring it under control, thereby not affecting all channels of any particular function 4

8403190303 840307 OFFICI AL COPY PDR ADOCK 00000370 S PDR %ZL

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.Mr. James.P.' 0'Reilly

' March 7, 196?

Page Two e If all " annulus functions" (i.e. cables and instrumentation in Annulus) were lost, charging and heat removal capability would be maintained. Flow paths to the reactor and to/from steam generators would be available for any fire postulated in the Annulus.

The attached figure shows minimum separation of ccbles used for shutdown functions which exit the containment and Annulus.

- Very truly yours.

Hal,B. Tucker

'PBN:dyh Attachment ec: Document Control Desk

-U. S. Nuclear Regulatory Commission Washington, D. C.

. Records Center Institute of Nuclear Power Operations-1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia Mr. W. T. Orders NRC Resident Inspector

.McGuire Nuclear Station 1 7-

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DUKE POWER COMPANY MCGUlRE NUCLEAR STATION - UNIT 2 Core Exit Temp. (3)

(T/C) - 3 Cables Press. Level - 1 Cable RCS Pr' essure - 1 Cable S/G Level (A, B, C, D) - 4 Cables Annulus RCS Hot Leg Temp. (4) 1RF-989 (RTD) - 4 Cables Containment k

45' 54*

99*

i Minimum Separation N 45 ft RCS Cold Leg Temp. (RTD) - 4 Cables Pressurizer Level - 1 Cable RCS Pressure - 1 Cable S/G Level (A, B &C, D) - 3 Cables

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