ML20134A837

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Forwards Addendum to Attachment 5,Part Ii,Rev 1 to Auxiliary Feedwater/Main Feedwater Failure Analysis Contained in
ML20134A837
Person / Time
Site: Rancho Seco
Issue date: 11/01/1985
From: Reinaldo Rodriguez
SACRAMENTO MUNICIPAL UTILITY DISTRICT
To: Thompson H
Office of Nuclear Reactor Regulation
References
RJR-85-539, TAC-59691, NUDOCS 8511110045
Download: ML20134A837 (2)


Text

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esuunSACRAMENTO MUNICIPAL UTILITY DISTRICT ' 6201 S Street, PO Boa 15830. Sacramento CA 958521830.19161 452 3211 AN ELECTHIC SYSTEM SERVING THE HE AHT OF CAllFOHNIA RJR 85-539 November 1, 1985 DIRECTOR OF NUCLEAR REACTOR REGULATION ATTN HUGH L THOMPSON JR DIVISION OF LICENSING U S NUCLEAR REGULATORY COMMISSION WASHINGTON DC 20555 00CKET NO. 50-312 LICENSE fi0. OPR-54

SUMMARY

AND SUPPLEMENTAL INFORMATION FROM TRANSIENT OF OCTOBER 2, 1985 Enclosed is an addendum to Attachment 5, Part II, Revision 1 -

Auxiliary Feedwater/ Main Feedwater Failure Analysis contained in the District's letter of October 25, 1935 (RJR 85-531).

The addendum includes the items discussed with various members'of our staff (00 November 1,1985.

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4 LN R. J. P0 RICUEZ ASSISTANT GENERAL %4AGER, NUCLEAR Attachment 00 0511110045 R51101 i PDH ADOCK 05000'112 \

P PDR RANCHO SECO NUCLt AH OtNf HATING STATION 14440 Twin Citm Howl Ha'ahl. CA 0'in1fl 9117!),120'H 33^) 7916

~3 ADDENDUM TO ATTACHMENT 5, PART II 7 AUXILIARY / MAIN FEE 0 WATER FAILURE ANALYSIS (REFERENCE RJR 85-531 There.are no single failures that will prevent manual initiation of AFW for any given plant conditions. Therefore, feedwater - i.e. main or auxiliary - will always be available to mitigate any accident or transient.

The District has reviewed the impact of single failures on the ability to provide main and/or auxiliary feedwater, and the highlights of this review are sumarized below.

I: MAIN FEE 0 WATER CONTROL VALVE The District believes there is no single failure in the ICS that will cause all main feedwater valves to go closed. It would take a number of component failures for the valves to close and cut off all feed-water. Therefore, the likelihood of this event is very small and does not pose a problem to plant operation. This evaluation is based on Integrated Control System Reliability System Analysis, BAW 1564 l 11: MAIN FEE 0 WATER PUMP CONTROL i

l Based on Integrated Control System Reliability System Analysis, BAW 1564, l there is only one failure which could cause loss of all main feedwater I following a reactor trip. This failure would be in the main feed pump l speed control circuitry and could reduce both main feed pump speeds to l minimum speed. The speed reduction would reduce pump discharge pressure

! to less than OTSG pressure, thus interrupting main feedwater flow. At'

! min. speed, the District will verify there will be an auto initiate of AFW flow. If required, the District will make,' prior to startup,-modif1-cations to assure this condition will not cause a loss of all feedwater.

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