L-MT-16-058, Supplement to License Amendment Request to Revise Battery Charger Surveillance Requirement 3.8.4.2

Supplement to License Amendment Request to Revise Battery Charger Surveillance Requirement 3.8.4.2

ML16327A465
Person / Time
Site:	Monticello
Issue date:	11/22/2016
From:	Gardner P Northern States Power Company, Minnesota, Xcel Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CAC MF7676, L-MT-16-058
Download: ML16327A465 (4)

Text

2807 West County Road 75 Monticello, MN 55362 (l Xcel Energy*

RES P 0 N S I B L E BY NAT U R E 800.895.4999 xcelenergy.com November 22, 2016 L-MT-16-058 10 CFR 50.90 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Monticello Nuclear Generating Plant Docket No. 50-263 Renewed Facility Operating License No. DPR-22 Supplement to License Amendment Request to Revise Battery Charger Surveillance Requirement 3.8.4.2 (CAC No. MF7576)

References:

1) NSPM (P. Gardner) to NRC, "License Amendment Request: Revise Battery Charger Surveillance Requirement 3.8.4.2," (L-MT-16-014), dated April4, 2016 (ADAMS Accession No. ML16099A097)

2) NRC (R. Kuntz) to NSPM (R. Loeffler), "DRAFT Request for Additional Information RE: Monticello license amendment request for Battery Charger SR revision (CAC MF7576)," dated August 31, 2016

3) NSPM (P. Gardner) to NRC, "Response to Request for Additional Information: License Amendment Request to Revise Battery Charger Surveillance Requirement 3.8.4.2 (CAC No. MF7576)," (L-MT-16-045),

dated October 3, 2016 (ADAMS Accession No. ML16277A486)

On April 4, 2016, the Northern States Power Company, a Minnesota Corporation (NSPM),

doing business as Xcel Energy, submitted a license amendment request proposing a change to the Technical Specifications (TS) for the Monticello Nuclear Generating Plant (MNGP).

The proposed change revises Specification 3.8.4, "DC Sources- Operating", Surveillance Requirement (SR) 3.8.4.2 to increase the required 125 VDC subsystems battery charger output current and to remove the second method specified to perform the surveillance (Reference 1). On August 31,2016, the U.S. Nuclear Regulatory Commission (NRC) requested additional information (RAI) pertaining to this proposed amendment (Reference 2).

The responses to this RAI were provided in Reference 3.

During development of the response to RAI 4 in Reference 3, it was clarified that Section 8.5.2.2 of the Updated Safety Analysis Report (USAR) incorrectly indicated that the rated DC

L-MT-16-058 Page 2 of 2 output was 80 amps for the 125 VOC main Battery Chargers (010 and 020) and 50 amps for the common standby 125 VOC Battery Charger (040), rather than stating 80 amps for all three chargers to meet TS requirements. The response to RAI 4 stated the USAR had been revised and the discrepancy was entered into the Corrective Action Program. Subsequent to submittal of the RAI response a verbal request was made by the NRC Project Manager for a copy of the revised USAR page. The revised USAR page is provided in the enclosure to this letter.

Summary of Commitments This letter makes no new commitments and no revisions to existing commitments.

I declare under penalty of perjury, that the foregoing is true and correct.

Executed on November :lJ, 2016.

~~~~

Peter A Gardner Site Vice President, Monticello Nuclear Generating Plant Northern States Power Company- Minnesota

Enclosure:

Supplement to LAR to Revise Battery Charger Surveillance Surveillance Requirement 3.8.4.2, Revised USAR Page cc: Administrator, Region Ill, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC State of Minnesota

ENCLOSURE MONTICELLO NUCLEAR GENERATING PLANT SUPPLEMENT TO LICENSE AMENDMENT REQUEST TO REVISE BATTERY CHARGER SURVEILLANCE REQUIREMENT 3.8.4.2 REVISED USAR PAGE (1 page follows)

MONTICELLO UPDATED SAFETY ANALYSIS REPORT USAR-08.05 Revision 32P SECTIONS PLANT ELECTRICAL SYSTEMS Page 4 of 8 Each 125 Vdc battery consists of 58 shock absorbent clear plastic cells of the lead-calcium alloy plate type. The manufacturer's rating for both of the 125 Vdc batteries is 95 Amperes at a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> discharge rate and 458 Amperes for a 1 minute discharge rate. These discharge rates are based on an ending terminal voltage of 1.81 Volts per cell at 7rF.

The battery chargers are 3 phase, full wave, silicon controlled rectifier, constant voltage, and current limiting chargers meeting NEC, NEMA and ASA standards.

Enclosures are NEMA Type I, convection cooled for operation up to 40oC ambient temperature. Chargers maintain 1/2% float and equalizing charge voltage regulation from 0-100% capacity with +/- 10% line voltage variation at I ~ <'?~

60Hz+/- 5%. Rated DC output The nominal output current limit setting is ,,

80 Amps for the main chargers and 50 amps for the common standby charger.

0 Each 125 Vdc charger is capable of carrying the normal 125 Vdc load and at the same time supplying additional charging current to keep the batteries in a fully charged condition.

The loads provided by the 125 Vdc systems are shown on Drawing NE-36640-3, Section 15.

A detailed description of the 125 Vdc system, including associated alarms and operator actions, was provided to the NRC in response (References 35 and 73) to Generic Letter 91-06, "Adequacy of DC Power Supplies" (Reference 74).

The NRC acknowledged receipt of the response to Generic Letter 91-06 and considers the issues closed for Monticello (Reference 48).

Battery chargers D1 0 and D20 have the ability to be re-powered from an alternate AC source via a permanently mounted local inlet receptacle and an alternate AC source input breaker installed on the charger breaker panel.

8.5.2.3 Performance Analysis The 125 Vdc battery system operates ungrounded with a ground-detection alarm set to annunciate the first ground which has sufficiently low resistance to ground to pick-up the ground detection relay. Multiple grounds, which are the only reasonable mode of failure, are extremely unlikely. Single ground faults will not blow fuses. Overcurrent protective devices are applied such that failure of a non-safety related load will not result in the loss of safety related equipment that does not itself fail in a safe condition.

Alarms are also provided for battery charger supply undervoltage and 125 Vdc bus high/low voltage conditions. The two main chargers have a high-voltage shutdown feature.

8.5.2.4 Loss of 125 Vdc Battery The safeguard systems supported by 125 Vdc power are redundant systems; each of which are supplied from separate 125 Vdc buses. Because of this redundancy, it is concluded that loss of a battery or its bus would not prevent safe shutdown of the plant.