ML13149A160

Request for Additional Information, Revise Technical Specification 3.8.1, AC Sources - Operating, Surveillance Requirement 3.8.1.10 to Increase Voltage Limit for Diesel Generator Load Rejection Test

ML13149A160
Person / Time
Site:	Wolf Creek
Issue date:	05/31/2013
From:	Lyon C Plant Licensing Branch IV
To:	Matthew Sunseri Wolf Creek
Lyon C
References
TAC ME9603
Download: ML13149A160 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 31,2013 Mr. Matthew W. Sunseri President and Chief Executive Officer Wolf Creek Nuclear Operating Corporation Post Office Box 411 Burlington, KS 66839

SUBJECT:

WOLF CREEK GENERATING STATION - REQUEST FOR ADDITIONAL INFORMATION RE: REVISION TO TECHNICAL SPECIFICATION 3.8.1, "AC SOURCES - OPERATING," SURVEILLANCE REQUIREMENT 3.8.1.10 (TAC NO. ME9603)

Dear Mr. Sunseri:

By letter dated September 19, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12272A279), Wolf Creek Nuclear Operating Corporation (the licensee) requested a license amendment to increase the voltage limit for the emergency diesel generator (DG) full load rejection test specified by Technical Specification (TS) 3.8.1, "AC

[Alternating Current] Sources - Operating," Surveillance Requirement (SR) 3.8.1.10.

The U.S. Nuclear Regulatory Commission (NRC) staff is currently reviewing the submittal and has determined that the information identified in the enclosed request for additional information (RAI) is needed in order for the NRC staff to complete its review. Please provide a response to the RAI within 45 days from the date of this letter.

M. Sunseri -2 ~

If you have any questions, please contact me at 301-415-2296 or via e-mail at Fred.Lyon@nrc.gov.

Sincerely, Carl F. Lyon, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-482

Enclosure:

As stated cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST FOR TS 3.8.1 WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION DOCKET NO. 50-482 8y letter dated September 19, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12272A279), Wolf Creek Nuclear Operating Corporation (the licensee) submitted a license amendment request (LAR) to increase the voltage limit for the emergency diesel generator (DG) full load rejection test specified by Technical Specification (TS) 3.8.1, HAC [Alternating Current] Sources - Operating," Surveillance Requirement (SR) 3.8.1.10. The U.S. Nuclear Regulatory Commission (NRC) staff has determined that the additional information requested below is needed to complete its review of the licensee's request.

1. On page 4 of Attachment 1 of the LAR, the licensee states that the switchyard voltage varies throughout the day, resulting in voltages that are sometimes at nominal, sometimes less than nominal, and sometimes higher then nominal at the DG electrical terminals. Section 2.2, "Reason for Proposed Change," of the LAR provides tabulated data of historical bus voltage variation and corresponding "Initial to Peak Voltage Difference." This table indicates that the maximum observed initial to peak voltage difference was 580 Volts (V) for "A" DG and 545 V for "8" DG. Historical trends provide an indication of DG performance and the NRC staff recognizes that several factors impact the voltage difference during load rejection tests. The licensee proposes to raise the maximum allowable bus voltage to 4992 V during the load rejection test. This will provide a range of more than 1000 V if the test is performed at the minimum allowable bus voltage.

Please provide details on the maximum allowable "Initial to Peak Voltage" difference that will be used to validate performance capabilities of the DG voltage regulator when compared with historical trends.

2. The purpose of the full load rejection test is to verify and demonstrate the DG governor and the voltage regulator functional capabilities during system perturbations. The full load rejection test is generally simulated by opening the DG output breaker with the DG at full load and verifying that there is minimal impact on the DG and the safety buses.

This test is intended to envelope the voltage and frequency variations that will be observed during a partial to full load rejection event with the DG connected to the safety buses.

In the event that the DGs are supplying the safety-related buses and a large load rejection event occurs, please discuss how the operating equipment on the safety-related buses will not be degraded if the DG output voltage spikes to 4992 V.

Enclosure

M. Sunseri -2 If you have any questions, please contact me at 301-415-2296 or via e-mail at Fred.Lyon@nrc.gov.

Sincerely, IRAJ Carl F. Lyon, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-482

Enclosure:

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