ML20207B076
| ML20207B076 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 07/11/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20207B065 | List: |
| References | |
| NUDOCS 8607170409 | |
| Download: ML20207B076 (4) | |
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UNITED STATES g
NUCLEAR REGULATORY COMMISSION
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jj WASHINGTON D. C. 20555 S. b.
A gv.....f SAFETY EVALUATION BY THE OFFICE OF hUCLEAR REACTOR REGULATION RELATED TO FACILITY OPERATING LICENSE NO. NPF-6 ARKANSAS POWER AND LIGHT COMPANY ARKANSAS NUCLEAR ONE, UNIT 2 DOCKET NO. 50-368
1.0 INTRODUCTION
By letter dated April 1,1986, Arkansas Power and Light Company requested a revision to Section 4.8.2.3.1.a.2 of AN0-2 technical specifications. The licensee provided additional information by letter dated June 25, 1986.
This revision is due to the proposed replacement of a 60 cells battery system by a 58 cells battery system in one of the two divisions of the Class 1E dc systems during July 1986 refueling outage of ANO-2. The replacement battery terminal voltage during float charging will be 124.7 volts instead of 129 volts for the existing 60 cells battery. Consequently, the proposed change in the surveillance requirement includes verification of 124.7 volts or greater on the terminals of the replacement battery.
2.0 EVALUATION As determined by the licensee, the AN0-2 Class 1E batteries are reaching the end of their service life and thus needed to be replaced. The licensee also noticed that the equalizing charge voltage which is higher than the float charge voltage of the battery, and is periodically applied for 8 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, was causing higher than rated voltage on the teminals of normally energized
Potter Brumfield" FDR relays. These relays were founc to be overheating due to higher thar. rated terminal voltage thus causing deterioration of the relay coil insulation and a potential for a consequential relay failure.
The licensee has proposed to replace the existing 60 cells battery system by a 58 cells battery system which will minimize the potential of higher than rated voltage on the terminals of the subject MDR relays and other Class IE dc components. The replacement battery will require equalizing charge to be at 135.1 volts instead of 139.8 volts for the existing 60 cells battery system and thus will reduce the possibility of overvoltage on the terminals of Class 1E dc components. The licensee has proposed to replace the battery in one division of Class IE dc system during July 1986 refueling outage and in the other division during the next refueling outage.
i 8607170409 86071T l
PDR ADOCK 05000368 P
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f The licensee's tests indicate that the new MDR relays, similar to the ones affected by the high equalizing charge voltage of the 60 cells battery, will perform reliably for at least one fuel cycle of ANO-2 operation. Based on this determination, the licensee has replaced all affected MDR relays by new ones. Presently, an effort is underway to redesign these relays using different irsulating material of higher voltage rating. The licensee maintains that the new installed MDR relays will reliably operate until the redesigned relays become available before the next refueling outage.
The replacement battery system with 58 cells has a higher ampere-hour capacity (2045A-hr.) than the existing 60 cells battery system (1350A-hr.). This higher rating of the battery will cause higher short circuit current in case of a fault in the de system. The licensee has performed short circuit calculations for the new battery and fouad that r:aximum available short circuit current for the new battery de system will be 12,000 amps which is well within the rating (14,000 amps) of the existing de switchgear. The licensee maintains that the switchgear does not need replacement and will adequately protect all dc Class IE equipment from the fault currents.
The existing battery rack is designed for 60 cells. The licensee has proposed to provide new, seismically qualified battery racks for each division of 58 cells batteries. One rack will be installed along with its 58 cells battery system during July 86 refueling outage whereas the other rack with its associated replacement battery system will be installed in the next refueling outage.
3.0 EVALUATION
SUMMARY
The staff has evaluated the proposed changes. Based on this evaluation, the considerations discussed above and based on the fact that the new battery bank is rated at a higher electrical storage capacity while maintaining the acceptable mir:imum discharge voltage of 105 volts, we find the proposed change acceptable.
4.0 ENVIRONMENTAL CCMSIDERATION This amendment involves a change in the installation or use of a facil.ty component located within the restricted area as defined in 10 CFR Part 20.
The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously published a proposed finding that the amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 951.22(c)(9).
Pursuant to 10 CFR %51.22(b), no environmental impact statement or environmental j
assessment need be prepared in connection with the issuance of the amendment.
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5.0 CONCLUSION
i We have concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public i
will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal contributor to this SE was I. Ahmed Dated: July li, 1986 j
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g 111986 ISSUANCE OF AMENDMENT N0.75 TO FACILITY OPERATING LICENSE NPF ARKANSAS NUCLEAR ONE, UNIT NO. 2 DISTRIBUTION Docket File 50-368 NRC PDR Local PDR PBD7 Reading FMiraglia JLee RSlee Attorney, ELD LHarmon EJordan BGrimes JPartlow.
TBarnhart (4)
WJones WRegan LKopp ACRS(10)
OPA LFMB EButcher NThompson