ML19241B031

Submits Info Requested 790320 Re Review of ECCS Subsys for Single Failure.No Single Failure or Operator Error Could Result in Significantly Adverse Consequences to ECCS Performance.No Tech Spec Mods Are Proposed

ML19241B031
Person / Time
Site:	Arkansas Nuclear
Issue date:	06/29/1979
From:	Trimble D ARKANSAS POWER & LIGHT CO.
To:	Reid R Office of Nuclear Reactor Regulation
References
1-069-21, 1-69-21, NUDOCS 7907110573
Download: ML19241B031 (2)

Text

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ARKANSAS POWER & LIGHT COMPANY POST OFFICE box 551 UTTLE ROCK. ARKANSAS 72203 (501)371-4000 June 29,1979 1-069-21 Director of Nuclear Reactor Regulation ATTN: Mr. R. W. Reid, Chief Operating Reactor Branch #4 U. S. Nuclear Regulatory Commission Washington, D. C. 20555

Subject:

Arkansas Nuclear One - Unit 1 Docket No. 50-313 License No. DPR-51 Re-Evaluation of ECCS Performance (File : 0930, 1510)

Gentlemen:

Pur suant to the request in your letter dated Maren 20, 1979- the follow-ing information is provided in support of your review of the Arkansas Nuc' ear One - Unit 1 (ANO-1) 'lectrical and instrumentation subsystems of the amergency core cooling system for single failure.

The Rotork submersible valve operators for valves CV-1050, CV-1410, CV-1414, and CV-1415 were designed to remain functional in a submerged condition for 30 days with a maximum fluid temperature of 271 F decaying to 130 F in 30 days, ant at a maximum pressure of 53 psig decaying to 5 psig in 30 days. Qualification tests for this type operator were done at a maximum pressure of 70 psig and a maximum temperature 370 F. There-fore these valves ca7 be depended upon to operate for at least 30 days under post-LOCA accident conditions.

CV-3824 (Service Water System discharge valve to the discharge fiume) is normally open. CV-3824 is a large 18" butterfly valve easily distin-guished (i.e., largest of three (3) valves located together) and located in a remote location within a controlled access area. During normal operation, power to the circuit breaker for this valve's motor is removed and the circuit breaker is tagged. Before either of these conditions can be changed, authorization of the shift supervisor in accordance with ad-ministrative procedures must be obtained and the valve realignment must be verified. We note a substantial physical effort would be required to manually close this large butterfly valve against the flow of the Service Water Sys tem.

Assuming CV-3824 was closed during' nonnal operation, two (2) means of detecting this occurrence are available to the control room operators.

While power to the circuit breaker fo- CV-3824's motor is renoved, position indication for the valve is still available in the control 79071105i3 MEMPEA MOOLE SOUTH UTILITIES SYSTEV 312

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• 1-069-21 Mr. R. W. Reid June 29, 1979 room. Also, with the service water discharge flow path blocked during nomal operation (i.e., CV-3824 was closed), the discharge pressure of ,

the service water pumps would create a high differential pressure across each operating pump. This condition would be alamed in the control room. (See Section 9.3.1 of At10-1 FSAR.) In addition to these two means of detect.c.g unauthorized closure of CV-3824 discussed above, each train of the Service Water System provides indication in the control roan of flow and high temperature conditions which would be noted almost immedia tely.

Based on the infomation discussed above, we can identify no single failure or operator error which would result in significantly adverse consequences to ECCS perfomance. Therefore, no amendment to our Tech-nical Specifications for CV-3823 or CV-3824 is proposed.

Very truly yours, C%%2$ $. ?6Y' David C. Trimble Manager, Licensing DCT:DGM:v b

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