ML20030A466
| ML20030A466 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 09/10/1975 |
| From: | Lamley R, Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8101090576 | |
| Download: ML20030A466 (3) | |
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ReguMory Docket Ei!e CODSlimCi5 h
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C0mp2Hy General Off.ces: 212 West Michsgan Avenue, Jackson, Michigan 49201. Area Code 517788-0550 September 10, 1975
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DOCKER 50-155, LICENSE DPR-6 9A~
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Transmitted herewith are three (3) executed and thirty-seven (37) conformed copies of a request for a change to the Technical Specifications of License DPR-6, Docket 50-155, issued to Consumers Power Company on May 1,196h for the Big Rock Point Plant.
This proposed change allows automatically bypassing the high condenser pressure reactor trip anytime drum pressures are less than 500 psig. The present Technical Specifications allow this trip to be bypassed below 350 psig.
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A Ralph B. Sewell Nuclear Licensing Administrator CC: JGKeppler, USNRC File 07-h s,1. 't v
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f i-10:7f CONSUMERS POWER COMPANY Docket No 50-155 Request for Change to the Technical Specifications License DPR-6 I.
For the reasons hereinafter set forth, the following changes to the Tech-nical Specifications of License' DPR-6 issued to Consumers Power Company on May 1,1964 for the Big Rock Point Plant are requested:
A.
Change note (e) which applies to the table contained in Section 6.1.3 to read as follows: "High condenser. pressure trip may be automatically by-passed anytime drum pressure is less than 500 psig."
II.
Discussion On May 30, 1975 Consumers Power Company submitted an Abnormal Occurrence Re-port regarding the drift of a pressure switch associated with the condenser low vacuum scram interlock. Similar reports were submitted May 8,1973 and November 13, 1973. The basic cause of these abnormal occurrences is that the existing pressure switches cannot be set much below 350 psig (the present i
Technical Specifications requirement) because of the restrictive reset char-acteristics of the condenser vacuum scram switch whicP resets at approximately 25 inches Hg.
It is extremely difficult to achieve a condenser vacuum of 25 inches Hg at a reactor pressure below 3ho psig. Thus, the pressure switch must be set at approximately 340 psig or greater and the drift associated with the switch between surveillance intervals can result in exceeding the specified set point.
The condenser low vacuum scram bypass is provided to allow vann-up of the main steam lines and the condenser so that the plant may be started up.
The pur-pose of the low vacuum trip is to insure that the main condenser is available as a heat sink for reactor output during power operation.
1 Based on a review of the FHSR, and other docketed data, we believe that the set point of 350 psig was arbitrarily selected.. We further believe that the purpose of this set point for the bypass feature is to insure that during power operation, the reactor will trip if the normal heat sink is lost and
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yet not unduly restrict start-up and warm
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Review of another BWR Technica Specification confirms this conclusion.
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~.They' indicate that the condenser low vacuum trip is allowed to be bypassed up toI600 psig. It is noted that the nomal reactor operating pressure for this SWR is approximately 1000 psi compared to greater than 1300 psi for Big.
Rock.
-Significant power operction does not occur at Big Rock Point below 1000 psig during plant start-up. Stess flow during reactor critical operation belov 500 psig seldom, if ever, exceeds 6% total rated steam flow. Loss of-the normal heat sink under these conditions would not cause a significant reactor pressure transient. Thus, the selection of 500 psig as the maximum set point for the bypass feature of the low condenser vacuum scram provides a large margin to the point where the trip function might be required to operate and yet allows flexibility during varm-up of the main steam lines and main con-denser.
III. Conclusion Based on the foregoing, both the Plant Review Committee and the Safety and Audit Review Board have concluded that this proposed change does not involve an unrevi~eved safety question.
CONSUMERS POWER COMPANY h-By w
R. A. Lamley, Vice P2thsident Sworn and subscribed to before me this 10th day of September 1975 II:en. Y l d1n]uk Alleen R. Nazaruk al Notary Public, Jackson County, Michigan My commission expires February 28, 1977
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o N C DISTRIBUTION FOFI PART 50 DOCKET MATERIAL (TEMPORARY FORlW)
CONTRO'L NO:
9714 FILE:
FROM: Consumers Power Company DATE OF DOC DATE REC'D LTR TWX RPT OTHER Jackson, Mich.
49201 Rainh R.
Mnuo11 9-10-75 9-12-75 XX TO:
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ORIG CC OTHER SENT)mC PDR XX SENT LOCAL PDR yx NRC 3 sinced 37 CLASS UNCLASS PROPINFO INPUT NO CYS REC'D DOCKET NO:
XXX 40 50-155 DESCRIPTION:
Ltr tra'ns the following:
ENCLOSURES:
Request for Change to Tech Specs for Lic. DPR-6 notarized 9-10-75 to allow automatically bypassing the high condenser pressure reactor trip anytime duringxdux drum pressures are less than 500 p,sig....
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(3 Orig & 37 CC ree'd) r_
PLANT NAME:
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