ML20150B065

Forwards Request for Addl Info Re Single Cell Battery Charging.Plant Mod to Permit Use of 40 Volt nonsafety-grade Battery Charger to Be Connected in Parallel W/Normal Full Capacity Equalization Charge Raised Questions

ML20150B065
Person / Time
Site:	Summer
Issue date:	06/27/1988
From:	Hayes J Office of Nuclear Reactor Regulation
To:	Nauman D SOUTH CAROLINA ELECTRIC & GAS CO.
References
TAC-68045, NUDOCS 8807110250
Download: ML20150B065 (4)

Text

. - . . . . .. .. . . . . . - . .

I

, a l

DISTRIBUTION l qDocketJ u e a c s  !

NRC POR Local PDR June 27, 1988 P021.r/f S..Varga (14E4)

G.'Lainas E. Adensam Docket No. 50-395 P. Andersen J. Hayes i OGC E.= Jordan (MNBB3302)

Mr.- D. A. Nauman 8.' Grimes (9A2)

Vice President, Nuclear Operations A. Toalston (8020)

South Carolina Electric & Gas Company ACRS (10)

Virgil C. Summer Nuclear Station P. O. Box 88 Jenkinsville, South Carolina 29065

SUBJECT:

SINGLE CELL BATTERY CHARGING - VIRGIL C. SUMMER NUCLEAR STATION (TAC NO. 63045)

South Carolina Electric & Gas Company._has made a plant modification at the Virgil C. Summer Nuclear Station to permit the use of a 40 volt non-safety-grade battery charger to be connected in parallel with the norm'al full capacity Lfety-grade battery charger. The 40 volt charger is used to' place an equalization charge on a string of 4 to.15 cells. of the 60 call 125 volt station battery banks. This method of placing an equalization charge on a limited number of cells is not discussed in the FSAR for the Summer Station and has not been reviewed by the NRC.

The NRC staff has received the 10 CFR 50.59 assessment and design details of the plant modification. Review cf this material has raised questions as to waether use of a partial charge for equalization tends to miask individual cell deterioration such that cells that are approaching their end-of-life are not replaced until they are completely bad. . Also, the use of fuses and other ,

design details of the modification raises certain questions regarding the l adequacy of the separation of the non-safety grade battery charger from the l Class-1E system.- Having completed the review of the 10 CFR 50.59 assessment .l and the design details of the plant modification, we find that additional information is required. Our request for additional information is contained in the enclosure. We anticipate having a meeting at the site following our )

review of your response. l

.l OC 5

_ ,i-Mr. D. A Nauman The reporting and/or recordkeeping requirements contained in this letter,.

affect. fewer.than ten respondents; .therefore, OMB clearance is. not required under P.L.96-511.

Sincerely,

_ k, )

John J. Hayes,'Jr., Froject-Hanager Project Directorate 11-1 Division of Reactor. Projects I/II~

Office of Nuclear. Reactor Regulation

Enclosure:

Request for Additional Information cc w/ enclosure:

See next page V

- (\ .

OFC :LA:PD :DSPR:PH: :0APR:0 1:DRPR :  :  :  :

$_:.. _gL..:. y__...:............:............:...___..................

NAME : SPA d ts a : JJ s:ch': (nsam  :  :.  :  ::

DATE : '6/28/88  : ' 6/J3/88  : '6/9$/88  :  :  :  :

/

0FFICIAL RECORD COPY l '

l

+-

Mr. O. A. Nauman South Carolina Electric & Gas Company Virgil C. Summer Nuclear Station cc:

Mr. William A. Williams, Jr.

Technical Assistant - Nuclear Operations Santee Cooper P.O. Box 764 (Mail Code 153)

Columbia, South Carolina 29218 J. B. Knotts, Jr. , Esq.

Bishop, Cook, Purcell and Reynolds 1400 L Street, d.W.

Wasnington, D. C. 20005-3502 Resident Inspector / Summer NPS c/o U.S. huclear Regulatory Commission Route 1, Box 64 Jenkinsville, South Carolina 29065 Regional Administrator, Region II U.S. Nuclear Regulatory Commission, ]

101 Marietta Street, N.W., Suite 3100 Atlanta, Georgia 30323 Chairman, Fairfield County Council P.O. Box 293 Winnsboro, South Carolina 29180 Attorney General Box 11549 Columbia, South Carolina 29211 l Mr. Heyward G. Shealy, Chief Bureau of Radiological Health South Carolina Department of Health and Environmental Control 2600 Bull Street Columbia, South Carolina 29201 South Carolina Electric & Gas Company '

Mr. A. R. Koon, Jr., Manager Nuclear Licensing r Virgil C. Summer Nuclear Station P. O. Box 88 Jenkinsville, Soutn Carolina 29065

REQUEST FOR ADDITIONAL INFORMATION VIRGIL C. SUMMER FORTY VOLT SATTERY CHARGER

1. What programs are in place (such as a trending program) to determine if a cell (s) that repeatedly requires equalization si.ould be replaced?

2. How many hours on the average during the year is it expected that the 40 volt charger will be connected to either safety-related battery? Is there a limit on the number of hours that the 40 volt charger is permitted to be connected?

3. If an insulation hianket is used over the safety-related battery bank while placing an 2"talization charge using the 40 volt charger, what procedures insure (nat the battery does not become overheated due to the blanket?

4. What protection is there to detect and isolate a high impedance fault between the 40 volt battery charger and the isolation fuses if the fault limits the current to a value less than the fuse rating?

5. The 10 CFR 50.59 assessment of the 40 volt charger states that the

' charger will not att as a short because the output resistors plus the circuit resistance will limit the current to an insignificant amcunt.

What is considered to be an insignificant amount?

6. The 10 CFR 50.59 assessment states that each cell of the battery can withstand 2.9 vo~ts @ 52.5A for approximately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. However, the isolation fuses are rated at 150 amperes. What protects the battery against equalization currents between 52.5 Ord 150 amperes in the event that the voltage regulator controls partially fail?

7. It is understood that administrative controls will be used to check every six hours against an overvoltage to the battery cells while using the 40 volt charger. What assessment has been made to determine the effect of a six hour maximum overvoltage condition?

8. What procedural steps are followed to insure that the station battery and its individual cells are operabla after removing the 40 volt charger?

9. Have the fuse cabinets, cable racks and their mountings (in the battery rooms) been seismically qualified? In particular, what assurance is there that the cable racks will not tear loose and directly or indirectly fault the battery?

10. Please send a copy of the pages from the instruction manuals INS 94B 245 and 300 that discuss the conditions for beginning or ending an equalization charge.

o

_--_--