ML20057A843

Forwards Rev to LAR Re Onsite Power Distribution Sys,Ac Distribution-Operating

ML20057A843
Person / Time
Site:	Calvert Cliffs
Issue date:	09/08/1993
From:	Denton R BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9309160018
Download: ML20057A843 (4)

Text

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. l SALTIMORE GAS AND i ELECTRI  !

1650 CALVERT CUFFS PARKWAY LUSBY, MARYLAND 20657-4702 ROBERT E. DENTON VICE PRESIDENT NUCLEAR ENERGY (4io) reo-44ss September 8,1993 U. S. Nuclear Regulatory Commission Washington,DC 20555 A'ITENTION: Document Control Desk

SUBJECT:

Calvert Cliffs Nuclear Power Plant i Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 l Revision to License Amendment Request; Onsite Power Distribution l Systems. AC Distribution - Operatine I

REFERENCES:

(a) Ixtter from R. E. Denton (BG&E) to Document Control Desk l (NRC), dated April 1,1993, License Amendment Request; Onsite l Power Distribution Systems, A.C. Distribution - Operating (b) Letter from R. E. Denton (BG&E) to Document Control Desk (NRC), dated July 22, 1993, Revision to License Amendment Request; Onsite Power Distribution Systems, AC Distribution -

Operating l

References (a) and (b) request a 24-hour Allowed Out-of-Service Time (AOT) when a 120 volt AC vital bus is being powered from the inverter backup bus. This AOT extension from the current i 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> was justified based upon: 1) the increased reliability of the vital bus when using the backup bus; 2) the requested AOT is shorter than the AOT for an inoperable diesel generator which has a similar safety significance; and 3) the low probability of a loss-of-offsite power during the

extended period.

NUREG-1432, " Standard Technical Specifications - Combustion Engineering Plants," allows 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to power an inoperable AC vital bus from its backup power supply (a constant voltage source l transformer). Our proposed change would allow 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to make this alignment. In order to maintain consistency with the standard, we hereby revise our request. Attached is a revised

" Insert A" for Attachments (1) and (2) of Reference (a).

l l Reducing the time allowed to power an inoperable 120 volt vital AC bus from its backup power supply does not change the arguments or conclusions of the " Determination of Significant Hazards" section of the original submittal and the request is still considered to not involve a significant hazard.

140085 9309160018 930908 PDR ADOCK 05000317 PDR N[

. .P ELL

l Document Control Desk September 8,1993 Page 2 Should you have any further questions regarding this matter, we will be pleased to discuss them with you.

Very truly yours,

)

1 STATE OF MARYLAND :

!  : TO %IT:

l COUNTY OF CALVERT :

I hereby certify that on the [ day of %Mber' a Notary Public of the State of Maryland iri and for

,193, before me, the subscriber, Ca lueet Counf t/ ,

personally appeared Robert E. Denton, being duly sworn, and states that he is Vice President of the Baltimore Gas and Electric Company, a corporation of the State of Maryland; that he provides the

! foregoing response for the purposes therein set forth; that the statements made are true and correct l to the best of his knowledge, information, and belief; and that he was authorized to provide the response on behalf of said Corporation.

I WITNESS my Hand and Notarial Scal: YbEIcIle to.1/1/2 Notary Public My Commission Expires: 9 My k /998 Date /

I RED /BDM/bdm/bjd

Attachment:

As stated cc: D. A. Brune, Esquire J. E. Silberg, Esquire l R. A. Capra, NRC D. G. Mcdonald, Jr., NRC T. T. Martin, NRC P. R. Wilson, NRC R. I. McLean, DNR J. H. Walter, PSC l

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I ATTACHMENT REVISED " INSERT A" FOR REFERENCE (A) l

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INSERT A 9 i

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l ACTION:

a. With less than the above complement of 4160 and 480-volt A.C. busses OPERABLE, j i restore the inoperable bus to OPERAHLE status within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> or be in at least IIOT 'j STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SIIUTDOWN within the following j 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. l

.i s b. With less than the above complement of 120-volt A.C. vital busses OPERAHLE, either:

1. Restore the de-energized vital bus to OPERABLE status by re-energizing the  ;

vital bus from its associated inverter within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or be in at least IIOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SIIUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />;

]

OR

2. Power the vital bus from the associated backup bus within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. Rest' ore the vital bus to OPERABLE status by re-energizing the vital bus from its associated inverter within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in at least IIOT STANDHY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SIIUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

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