ML16019A397

Request for Additional Information Related to Amendment Request for Emergency Diesel Generator Minimum Voltage Surveillance Requirements

ML16019A397
Person / Time
Site:	Davis Besse
Issue date:	01/20/2016
From:	Blake Purnell Plant Licensing Branch III
To:	Boles B First Energy Services
Purnell B, NRR-DORL 415-1380
References
CAC MF6060
Download: ML16019A397 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 January 20, 2016 Mr. Brian D. Boles Site Vice President FirstEnergy Nuclear Operating Company Mail Stop A-DB-3080 5501 North State, Route 2 Oak Harbor, OH 43449-9760

SUBJECT:

DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO. 1 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO AMENDMENT REQUEST FOR EMERGENCY DIESEL GENERATOR MINIMUM VOLTAGE SURVEILLANCE REQUIREMENTS (CAC NO. MF6060)

Dear Mr. Boles:

By application dated April 1, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15091A143), as supplemented by letter dated October 14, 2015 (ADAMS Accession No. ML15287A251 ), FirstEnergy Nuclear Operating Company (the licensee) submitted a license amendment request for the Davis-Besse Nuclear Power Station, Unit No. 1.

The proposed amendment would change certain technical specification, minimum voltage and frequency acceptance criteria for emergency diesel generator testing.

The U.S. Nuclear Regulatory Commission staff is reviewing your submittals and has determined that additional information is required to complete the review. A response to the enclosed request for additional information is requested to be provided within 30 days from the date of this letter.

B. Boles If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1380.

Sincerely, Blake Purnell, Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-346

Enclosure:

Request for Additional Information cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION AMENDMENT REQUEST TO CHANGE EMERGENCY DIESEL GENERATOR MINIMUM VOLTAGE AND FREQUENCY REQUIREMENTS FIRSTENERGY NUCLEAR OPERATING COMPANY DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO. 1 DOCKET NO. 50-346 By application dated April 1, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15091A143), FirstEnergy Nuclear Operating Company (the licensee) submitted a license amendment request (LAR) for the Davis-Besse Nuclear Power Station, Unit No. 1. The LAR would revise the minimum voltage and frequency acceptance criteria for emergency diesel generator (EOG) testing specified in surveillance requirements (SRs) associated with Technical Specification 3.8.1, "AC Sources - Operating."

By letter dated September 21, 2015 (ADAMS Accession No. ML15222A179), the U.S. Nuclear Regulatory Commission (NRC) staff requested additional information to complete its review of the LAR. The licensee provided supplemental information in response to the request for additional information (RAI) by letter dated October 14, 2015 (ADAMS Accession No. ML15287A251). The staff is requesting clarification of the information provided in the October 14, 2015 letter BACKGROUND:

On December 17, 2015, the NRC staff held a public meeting (ADAMS Accession No. ML16006A351) with the licensee to get clarification on the responses and excerpts from calculation provided with the October 14, 2015, letter. During the meeting, the licensee provided the following clarifications:

1. The proposed 4070 volt (V) setpoint is required by the permissive relays to close the EOG output breaker and energize the bus. This is the bus voltage and not the EOG output voltage.

2. The EOG automatic voltage regulator is set at 4088 V. At this voltage setting, the EOG will provide sufficient voltage during the starting transient to ensure the ability to start and run required loads.

During an emergency start, the EOG operates in isochronous mode. Typically the voltage regulator has a preset value of 4160 V (or higher) as measured at EOG output terminals, to ensure that the safety bus has adequate voltage to support equipment operation. This is generally considered the steady state EOG output voltage. During voltage transients due to load sequencing or other perturbations, the voltage regulator tries to restore the output voltage to the preset value (4160 V). In order to raise or lower the EOG output voltage, the EOG operation has to be changed from "emergency" mode to "droop" mode.

ENCLOSURE

The SRs are not specific as to the exact location of the verification point (e.g., EOG output terminals, output breaker, or switchgear) for the voltage setpoints. Typically, licensees validate all EOG output voltage requirements at a common point. During the public meeting on December 17, 2015, the licensee stated that the proposed steady state voltage (4088 V) was evaluated at the output of the EOG as maintained by the voltage regulator. The proposed 4070 V setpoint for EOG breaker closure permissive and load sequencing analysis was assumed at the EOG bus. A subsequent email from the licensee (ADAMS Accession No. ML16006A367) confirmed that this voltage is taken at the EOG bus and not at the 4160 V unit substation bus.

QUESTIONS:

1. Transient analysis programs typically use a constant voltage at a generation source to establish a voltage profile in the auxiliary power system during system perturbations.

The excerpts from MPR Calculation 0200-0087-RP01 provided with the October 14, 2015, letter, indicate that 4088 V was assumed at the EOG terminals for the analysis.

Confirm that this parameter was held constant to evaluate:

a) The 4070 V setpoint established for breaker closure permissive.

b) The response of the EOG during the load sequencing process, starting at time of breaker closure when the voltage regulator is trying to maintain 4088 Vat EOG terminals.

2. Provide the procedurally controlled setpoint for EOG output voltage for the emergency mode of operation.

3. The October 14, 2015, response to RAI 3 states: "The operating procedure requires a voltage between 4200 V and 4250 V on the bus prior to manually starting the motor driven feedwater pump (MDFP)." Clarify if the procedure requires EOG mode of operation changed from "emergency" mode to "droop" mode to vary output.

8. Boles If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1380.

Sincerely, IRA/

Blake Purnell, Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-346

Enclosure:

Request for Additional Information cc w/encl: Distribution via Listserv DISTRIBUTION:

PUBLIC RidsNrrLASRohrer Resource LPL3-2 R/F RidsNrrPMDavisBesse Resource RidsAcrsAcnw_MailCTR Resource RidsRgn3MailCenter Resource RidsNrrDeEeeb Resource SBasturescu RidsNrrDorl Resource GMatharu RidsNrrDorlDpr Resource JHauser RidsNrrDorllpl3-2 Resource ADAMS Access1on No. ML16019A397

• b1y memo OFFICE NRR/DORL/LPL3-2/PM NRR/DORL/LPL3-2/LA NRR/DE/EEEB/BC NAME BPurnell SRohrer *JZimmerman DATE 1/20/16 1/20/16 1/14/16 OFFICE NRR/DORL/LPL3-2/BC (A) NRR/DORL/LPL3-2/PM NAME JPoole BPurnell DATE 1/20/16 1/20/16 OFFICIAL RECORD COPY