ML15222A179

Request for Additional Information Related to Amendment Request for Emergency Diesel Generator Minimum Voltage Surveillance Requirements (TAC No. MF6060)(L-15-117)

ML15222A179
Person / Time
Site:	Davis Besse
Issue date:	09/21/2015
From:	Blake Purnell Plant Licensing Branch III
To:	Boles B FirstEnergy Nuclear Operating Co
Blake Purnell, NRR/DORL
References
L-15-117, TAC MF6060
Download: ML15222A179 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 21, 2015 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 (TAC NO. MF6060)(L-15-117)

Dear Mr. Boles:

By application dated April 1, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15091A143), FirstEnergy Nuclear Operating Company (FENOC, the licensee) submitted a license amendment request for the Davis-Besse Nuclear Power Station, Unit No. 1. The proposed amendment requests changes to certain technical specification minimum voltage and frequency acceptance criteria for emergency diesel generator testing.

The U.S. Nuclear Regulatory Commission (NRC) staff is reviewing your submittal and has determined that additional information is required to complete the review. The specific information requested is addressed in the enclosure to this letter. This request was discussed with FENOC personnel during a teleconference on August 17, 2015. A response to the enclosed request for additional information is requested to be provided by October 9, 2015.

The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources.

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 111-2 and Planning and Analysis Branch 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 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 (FENOC, the licensee) submitted a license amendment request (LAR) for the Davis-Besse Nuclear Power Station, Unit 1 (DBNPS). The proposed amendment requests changes to certain technical specification minimum voltage and frequency acceptance criteria for emergency diesel generator (EOG) testing.

Section 3 of the LAR provides the technical evaluation for minimum EOG starting and steady state voltage and frequency. For EOG starting, the existing minimum voltage acceptance criterion will be increased from 4031 V to 4070 V. The minimum acceptable voltage of 4070 V was determined based on the bus voltage required by the EOG output circuit breaker to close.

In addition, the existing EOG minimum steady state voltage acceptance criteria would be increased from 3744 V to 4088 V. The LAR states that a more restrictive minimum steady state voltage provides assurance that during EOG loading, the voltage response recommendations of Safety Guide 9, "Selection of Diesel Generator Set Capacity for Standby Power Supplies" (ADAMS Accession No. ML12305A251), can be satisfied.

The NRC staff notes that:

(a) Safety Guide 9, Section C4, pertains to the starting and load-accepting capabilities of the diesel generator and states, in part, that the diesel generator should be designed such that the frequency will not decrease, at any time during the loading sequence, to less than 95 percent of nominal and the voltage will not decrease to less than 75 percent of nominal.

(b) The EOG minimum steady state voltage and frequency acceptance criterion, as specified in surveillance requirement 3.8.1.2, 3.8.1.8.b, 3.8.1.11.c.3, 3.8.1.14.b, and 3.8.1.15.c.3, is based on the performance capability of the EOG governor and voltage regulator after perturbations due to load sequencing have dampened and the EOG is in a steady state operating mode.

The U.S. Nuclear Regulatory Commission (NRC) staff has determined that the additional information below is needed to complete its review of the application.

Enclosure

(1) According to the Updated Final Safety Analysis Report (UFSAR) (ADAMS Accession No. ML14339A821 ), Table 8.3-1 for EOG loading, Step 1 loading includes loads that do not trip on a loss of power and a 400 horse-power (hp) component cooling water pump that starts as soon as the EOG output breaker closes with the proposed allowable voltage of 4070 V. A large motor (e.g., make up pump} starts within 2.5 seconds of breaker closure.

Explain how the evaluation performed demonstrates that the voltage drop (Attachment H of the LAR) during this stage of EOG loading satisfies Safety Guide 9 criterion and the minimum voltage required for running equipment.

(2) Provide the acceleration time for the large motors started in load sequencer Step 1 and 1a. Provide a list of the motor-operated valves that are required to operate during this period. Provide a summary of the assumptions, methods, and results of the evaluation performed for this additional loading.

(3) The NRC staff notes that an 800 hp motor-driven feedwater pump can be manually loaded onto the EOG.

Provide a summary of the assumptions, methods, and results of the evaluation performed to demonstrate that the voltage drop in the auxiliary system will not adversely impact safety-related equipment if the EOG was operating at the steady state voltage of 4088 V prior to pump start.

(4) For surveillance requirements associated with steady state operation of the EOG, the LAR proposes the following limits: Steady state voltage~ 4088 V and::;; 4400 V, and frequency ~ 59.5 Hz and ::;; 60.5 Hz.

a. Explain how the maximum postulated loading evaluated in Attachment H considered the worst-case combination of allowable voltage and frequency coupled with large pumps operating at run out conditions.

b. Explain how fuel oil consumption for EOG operation was evaluated after establishing the maximum EOG loading. Compare the revised EOG fuel oil consumption results with the design-bases and TS requirements for the EOG day tank and bulk storage (week) tank.

(5) In the LAR, the licensee stated that a transient analysis computer model was used to analyze the voltage and frequency response of the DBNPS EDGs during load sequencing associated with the design-basis loss of coolant accident and loss of offsite power. The licensee states this analysis showed that DBNPS EDGs are capable of starting their dedicated engineered safety features loads in the required sequence while meeting the minimum voltage and frequency recommendations of Safety Guide 9 for the loading sequence and each load sequence time interval.

Provide a summary of the EOG frequency and voltage response in a tabulated form with assumptions made for starting voltage and frequency.

B. 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 111-2 and Planning and Analysis Branch 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:

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