ML20126E324

Advises of Operating Practices Re Plant Main Steam Bypass Valve,Changes in Operating Procedures in Effect for Power Run & Details for Making Change

ML20126E324
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	06/23/1967
From:	Haueter R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Morris P, Skovholt D US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8101190435
Download: ML20126E324 (3)

Text

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1 Re: Docket 50-155 June 23, 1967

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$Ng0N p- 1' Dr. P. A. Morris, Director %MpgG f Division of Reactor Licensinc *# g t# 8 "

United States Atmic Energy Cocnission Q) g Washington, D. C. 20545 g cn

Dear Dr. No:

" . o : Attention: Mr. D. J. Ekovholt Recent discussions with our AEC-Cacrpliance inspector and your staff indicate that there is same confusion about our current operatinc practices relatinc to the BiC Roch Point main stess bypass valve. Durinc part of our last power run (Novmber,1966 throuch May, 1967), the automatic operation of the main steam bypass valve was lir.ited to 50 We load. The valve control was placed in the manual porition whenever the plant was operating at 50 We or creater. It was intended that this chance in operatinc procedure be noted in our last s miannual report to the AEC. It was not reported because of an inadvertent editorial emission. this letter is intended to report the chance in operatinc procedure which shall also be in effect for the current power run and also to detail the reasons for ankinC the chance.

Since the emplete replacement of the electronic controls in 1965, the bypasc valve has perfomed quite adequately with the exception of the incident of August 8,1966, and this probic= van innediately detected and corrected. It is apparent however, that scoe incidence of failure vill always be present in the system, and Consuocrs Power Campany has decided to install a d-c rotor operated isolation valve innediately ahead of the bypass valve as a backup valve. Also, since there is only the one trancmission line into the plant, and tripout of the line results on a loss of nomal station power, it has been decided to provide a second source of station power by brincinC a 46 Ky transmission line into the plant substation. An autenatic throwaver to the swi m i supply will occur in the event of los: of nomal station power. Material for both of these modifications is on Pm/94Ktg

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Dr. P. A. Morric 2 -

June 23, 1967 order and it will be instaned during the next refuelinc outace in- '

early 1968, barrimC %weted delayc. }

Testing of the bypass valve with the new electronic controls,up to the maximum trip levels that the system can accatmodate i still remains to be done. We have not felt ht the number of thermal transients to the fuel necessary for a thorough test program was desirabic because of the fuel failures that have been experienced in the stainless steel and R 8: D fuels. Also, since we are now planninc to install the isolation valve and backup. station power supply, vc .i feel that it is prudent to delay further testing until this equi ment l is instaned. It is for the above two reasons that the 30 W trip test oricinally planned for the recently casqpleted refueling was deferred.

Experience to date indicatec that the bypass valve vill .'

probably not prevent a reactor scram at load rejecticas above 50 W until further testiac and adjustments are ande. Therefore, during the next run the bypacc valve vin be operated on manual at, loads above 50 We since this type of operatice win virtum13y elihAsate any possibic spurious valve openiac that micht otherwise occur,'w A reactor ,

ceram vill be accepted in the event of a line trip a$ above $ E c. ,

The incidence of line trips from lightniac is quitalow, with '

one lighning trip during the past five years. , ' ' '/^

In our judcement, the aboys change is,operatine, procedures does not involve a chance in the technical specifications incorporated in our licence or an unreviewed safety probl4sn. Our review'jef the FESR showc that neither the probability of the oocurrence nor the consequences- Lt of the accidente are increased by this chance nor is there a possibic occurrence of any significant new accident. 1 We trust that the above discussion vin ' clarify our projected plana reEarding the Bic Rock Point bypass valve.

Yours very truly,

f. r M RL11/mp R. L. Haucter Assistant Electric Production Superintendent - Nuclear 1 CC: JUEeppler 1

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I I Dr. Morris ACTION NECESSARY O CONCURRENCE Q DATE ANSWERED.

NO ACTION NECES5ARY Q COMMENT ] BY.

C L A551F.: POST Of flCE FILE CODt; y 30Cim:r ."A-155 REG NO:

DESCRIPTION; l Muse Se Unclaushed) REFERRED TO DATE RECEIVED BY DATE Ltr. advising as in regard to their surrect operating practicos relating pleury: 6 17 to the Big Rock Point Main steem ny6T ettras - POR ACTI0al bypass valve..........

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