ML14328A460

MF1022, Request for Additional Information (Rai), LAR Revision to Diesel Generator Initiation - Degraded Voltage Time Delay Setting Change

ML14328A460
Person / Time
Site:	Nine Mile Point
Issue date:	11/24/2014
From:	Bhalchandra Vaidya Plant Licensing Branch 1
To:	David Gudger, Kristensen K, Reynolds R, Varga B Exelon Generation Co
Vaidya B, NRR/DORL/415-3308
References
TAC MF1022
Download: ML14328A460 (2)

Text

From: Vaidya, Bhalchandra Sent: Monday, November 24, 2014 12:49 PM To: Kristensen, Kenneth J:(NMP)

(kenneth.kristensen@exeloncorp.com); Varga, Brandon T:(NMP)

<brandon.varga@exeloncorp.com>

(brandon.varga@exeloncorp.com); Reynolds, Ronnie J.:(GenCo-Nuc) (Ronnie.Reynolds@exeloncorp.com);

David.Gudger@exeloncorp.com Cc: Razzaque, Muhammad; Jackson, Christopher; Beasley, Benjamin; Matharu, Gurcharan; Mathew, Roy; Martinez-Navedo, Tania; Tilton, Caroline; Stattel, Richard; Thorp, John; Elliott, Robert

Subject:

Request for Additional Information (RAI), Nine Mile Point Unit 1, MF1022, LAR Re: Revision to Diesel Generator Initiation - Degraded Voltage Time Delay Setting Change

SUBJECT:

NINE MILE POINT NUCLEAR STATION, UNIT NO. 1 - LICENSE AMENDMENT REQUEST

- RE: DIESEL GENERATOR INITIATION - DEGRADED VOLTAGE TIME DELAY SETTING CHANGE WITH OPPORTUNITY TO SUPPLEMENT (TAC NO. MF1022)

By letter dated March 8, 2013, Nine Mile Point Nuclear Station, LLC (NMPNS) submitted a license amendment request (LAR) for Nine Mile Point Nuclear Station, Unit No. 1 (NMP1). The proposed amendment would modify Technical Specification (TS) Table 3.6.2i, "Diesel Generator Initiation," by revising the existing 4.16kV Power Board 102/103 Emergency Bus Under-voltage (Degraded Voltage)

Operating Time value and updating the Set Point heading title. By letter dated May 16, 2013, you submitted the response to the NRC staff request for supplemental information, required to complete the Acceptance Review in accordance with LIC-109. In addition, by letters dated July 8 and July 16, 2014, you submitted responses to the NRC staff requests for additional information and to confirm the results of the preliminary study referenced in the May 16, 2013 submission. Additionally, a Component Design Basis Inspection (CDBI) inspection took place at Nine Mile point Units 1 and 2 from September 8, 2014, to October 10, 2014, and the licensee was made aware of its findings in the exit meeting on October 10, 2014. The Inspection Report No. 05000220/2014007 dated November 20, 2014, (ADAMS ACCESSION NUMBER: ML14325A019) documents the findings.

The Nuclear Regulatory Commission (NRC) staff has determined that additional information, which is provided below, is needed to complete its review of this License Amendment Request.

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REQUEST FOR ADDITIONAL INFORMATION NINE MILE POINT NUCLEAR STATION, LLC NINE MILE POINT UNIT 1 DOCKET NO. 50-220 Inspection Report Nos. 05000220/2014007 dated November 20, 2014, (ADAMS ACCESSION NUMBER:

ML14325A019) documents the findings for the Component Design Basis Inspection (CDBI) that took place from September 8, 2014, to October 10, 2014. This Inspection Report describes the following findings/violations for Nine Mile point Unit 1 with respect to the failure to implement design control measures to verify that the connected Class 1E loads would not be damaged or become unavailable for a design basis LOCA coincident with a sustained degraded voltage condition.

1. Failure to adequately evaluate the transient voltages to the Class 1E accident initiated motors and MOVs on the-safety related buses and MCCs. Specifically, Exelon calculations incorrectly used 115 kV grid voltage instead of incorporating the 3.5% grid voltage sag into calculation NIMO-ELMS-AC01. Consequently, Exelon did not verify and assure adequate voltages would be available to Unit 1 Class 1E accident initiated motors, MOVs, and control circuits powered from the 4160 V, 600 V, and 120 V distribution systems during a design basis LOCA with subsequent unit trip and resulting sag of the 115 kV grid.

2. The inspection team noted that the NMP Unit 1 electrical design calculations had not evaluated for the following conditions:

a. Connected Class 1E loads would not be degraded or rendered inoperable for a design basis LOCA and a sustained degraded voltage condition between the degraded voltage dropout setting (3705 V) and the loss of voltage setting (3200 V) for the degraded voltage time delay of 21 +/- 3 seconds and subsequent reconnection to the emergency diesel generator.

b. Safety-related equipment that is operating or safety-related loads that are required to start (motors, motor operated valves, etc.) had not been evaluated to ensure that their protective devices would not actuate during a sustained degraded grid condition coincident with a design basis LOCA.

For the conditions identified above, the required equipment may not be available after transfer of safety busses to the onsite power sources.

Please provide the detailed evaluation and justification to implement adequate design control measures to verify that the critical Class 1E loads that operate during the first 24 seconds of a LOCA would not be damaged or become unavailable for a design basis LOCA coincident with a sustained degraded voltage condition. Also, please provide the corrective actions planned and taken, including the review of the extent of condition, for the resolution of all the CDBI findings.

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Please contact me, ASAP, to schedule a tele-conference between the NRC staff and the licensee to discuss this request and to provide a firm commitment from the licensee for the Response to this RAI.

Thanks Bhalchandra K. Vaidya Licensing Project Manager NRC/NRR/DORL/LPL1-1 (301)-415-3308 (O) bhalchandra.vaidya@nrc.gov