B16612, Forwards Response to 970626 RAI Re Proposed Rev to TS Surveillance 4.8.2.1.c.4

Forwards Response to 970626 RAI Re Proposed Rev to TS Surveillance 4.8.2.1.c.4

ML20151K044
Person / Time
Site:	Millstone
Issue date:	07/30/1997
From:	Brothers M NORTHEAST NUCLEAR ENERGY CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
B16612, NUDOCS 9708050312
Download: ML20151K044 (6)

Text

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Waterford. CT 06335-0128 (860) 447-1791 Fax (860) 444-4277 The Northeast Utilities System JUL 301997 i

Docket No. 50-423 B16612 Re: 10CFR 50.90 l- U.S. Nuclear Regulatory Commission

. Attention: Document Control Desk Washington, DC 20555 -

Millstone Nuclear Power Station Unit No. 3 Proposed Revision to Technical Specification D.C. Sources (PTSCR 3-19-97)

Response to Reauest for Additional Information In a letter dated May 14 31997, Northeast Nuclear Energy Company (NNECO) proposed to amend Operating License NPF-49 by revising Millstone Unit No. 3 Technical Specification Surveillance 4.8.2.1.c.4. The NRC Staff in a letter dated June 26,1997 requested NNECO to provide additional information to support our proposed license amendment.

Attached are our responses to the NRC ' Staff's questions. If you have any additional questions, please contact Mr. D. Smith at (860) 437-5840.

NORTHEAST NUCLEAR ENERGY COMPANY AA d M. H. Bro'thers ~

Vice President - Millstone Unit No. 3 cc: H. J. Miller, Region 1 Administrator J. W. Andersen, NRC Project Menager, Millstone Unit No. 3 f A. C. Cerne, Senior Resident inspector, Millstone Unit No. 3 5 W. D. Travers, PhD, Director, Special Projects Office 9700050312 970730 PDR

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4 Docket No. 50-423 j B16612 1

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l Attachment 1 Millstone Nuclear Power Station, Unit No. 3 i

NNECO's Commitments i i

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i July 1997

r U.S. Nuclear Regulatory Commission i

',B,16612\ Attachment 1\Page 1 i

Enclosure List of Regulatory Commitments >

The following table identifies those actions committed to by NNECO in this document. Please notify the Manager - Nuclear Licensing at the Millstone l Nuclear Power Station Unit No 3 of any questions regarding this document or any associated regulatory commitments.

Commitment Commitment Date or Outage i

NONE NONE NONE ]

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Docket No. 50-423 B16612 Attachment 2 l

Millstone Nuclear Power Station, Unit No. 3-Proposed Revision to Technical Specification D.C. Sources (PTSCR 3-19-97)

Response to Reauest for Additional Information 1

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July 1997

, , U.S. Nuclear Regulatory Commission

., B.16612\ Attachment 2\Page 1 Millstone Nuclear Power Station, Unit No. 3 Response to Reauest for Additional Information for PTSCR 3-19-97

1. Provide the background and the reason for changing the surveillance requirement voltage from 125 volts to greater than or equal to 132 volts?

Response

Presently, Technical Specification Surveillance 4.8.2.1.c.4 requires the 18 month performance test of the IE battery chargers to be performed at 125VDC. In LER 97-01-00, dated February 3,1997, we reported that it was identified that battery charger surveillance testing was being performed in a manner that was not in verbatim compliance with the 125VDC requirement of Technical Specification 4.8.2.1.c.4. The actual surveillance testing was performed at a voltage greater than 125VDC. In Section IV of LER 97-01-00, we committed to submit to the NRC Staff any required proposed changes to the Technical Specifications.

NNECO in a letter dated May 14, 1997, provided the NRC Staff with a proposed revision to the Technical Specifications that revised the test value for the battery chargers to 2132VDC. The 18 month performance test is intended to demonstrate that the chargers can meet their design basis requirements. This requires that the charger be capable of carrying the worst case load while recharging the battery within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (Ref. Reg Guide 1.32, FSAR Section 8.3.2.1.2).

The chargers are set at a float voltage of 132VDC to 135VDC during normal operation based on the manufacturer's recommendations to obtain optimum performance and life from the cells. The vendor recommended setting of 2 132VDC assures compliance with the design basis requirement. Additionally, the charger will respond automatically as required during a design basis event at the vendor recommended setting.

In summary, this is the basis for selecting value of 2132VDC for the 18 month battery charger performance test. This value is in accordance with the manufacturer's recommendations and assures the chargers are capable of automatically performing their design basis function with adequate margin.

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., , U.S. Nuclear Regulatory Commission 816612\ Attachment 2\Page 2

2. Is the equipment supplied by the battery qualified for voltage greater than or equal to 132 volts? ,

Response

The test voltage of 2132VDC is compatible with the ratings of the supplied equipment. The maximum voltage allowed by the design basis and operating procedure is < 140VDC ( Ref.- FSAR Q430.41, SER section 8.3.2.1 ). This allows the chargers to function in the equalize mode 139.8VDC (2.33VPC) when required as recommended by the manufacturer.

3. What is the vendor recommended safe voltage for the individual cell specific gravity allowed by the Technical Specifications? .

Response

To meet the design requirement of the 125VDC electrical system, a battery rated at the nominal specific gravity of 1.215 was procured. The vendor recommends that a cell with a specific gravity of 1.21510.010 requires a float voltage of 132VDC to 135VDC. Also, in accordance with the manufacturer's recommendation when a cell (s) deviates by more than 0.010 (10 points) from the nominal average 1.215; actions such as a full bank equalizing charge (139.8VDC) or single cell charge (2.33VPC) may be necessary. Therefore, 2132VDC is a safe voltage for a cell at the Technical Specification minimum specific gravity of 1.200 and in accordance with manufacturer's recommendation an even higher voltage (i.e. equalizing) is acceptable and required under certain conditions.