ML20134K511

Clarifies Statement Made in 1992 Ltr from ANO to NRC Re Testing & Surveillance Requirements for Alternate AC DG

ML20134K511
Person / Time
Site:	Arkansas Nuclear
Issue date:	11/07/1996
From:	Mims D ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9611190149
Download: ML20134K511 (3)

Text

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• A Entergy Opsrations, Inc.

-== ENTERGY ma sa 333 RusscMc AR 12301 l

Tcl501853 5000 November 7,1996 0CANI19606 U. S. ' Nuclear Regulatory Commission Document Control Desk Md Station PI-137 i

Washington, DC 20555

Subject:

Arkansas Nuclear One - Units 1 and 2 Docket Nos. 50-313 and 50-368 License Nos. DPR-51 and NPF-6 Clarification of Testing and Surveillance Requirements for the AAC Diesel Generator Gentlemen:

The purpose of this letter is to clarify a statement made in a 1992 letter from Arkansas Nuclear One (ANO) to the NRC regarding the testing and surveillance requirements for the alternate AC (AAC) diesel generator. It appears there was a misinterpretation of this statement as evidenced by the discussion of surveillance testing in the AAC diesel generator safety evaluation report (SER). The misinterpretation was first recognized during a recent self-assessment regarding the implementation of regulatory commitments for the AAC diesel generator.

During the review of the safety evaluation report dated December 18,1992, " Conceptual Design for Station Blackout Modification - Arkansas Nuclear One, Units 1 and 2" (0CNAl29208), it appears there was a misinterpretation of an ANO statement made in a letter to the NRC dated August 14,1992, " Conceptual Design for Station Blackout Modification" (0CAN089203). The SER states in section 3.4, " Testing and Maintenance," that "The licensee stated that all testing andsurveillance requirements thatpresently apply to the Class 1E emergency dieselgenerators (EDGs) will be applied to the AACpower source. "

While this is an accurate restatement of the earlier correspondence to the NRC, the statement in ANO's August 14, 1992, letter was intended to convey the desire at that point in time regarding use of the AAC diesel generator. At that time, ANO was considering utilizing the AAC diesel generator as a dedicated substitute for a Class IE EDG if a decision was made to petition the NRC for a technical specification LCO extension. No distinction was drawn in the SER that this level of testing and surveillance was dependent on receiving favorable NRC consideration regarding technical specification limiting condition for operation (LCO) relief on 9611190149 961107 r

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.,the Class IE EDGs. The misunderstanding of the statement was overlooked during ANO's initial review of the SER in December 1992.

J ANO's current philosophy regarding utilizing the AAC diesel generator for allowed outage time (AOT) extensions is provided in ANO's letter to the NRC dated May 2,1996,

" Technical Specification Change Request Regarding Emergency Diesel Generator Allowed Outage Time Extension" (0CAN059603). In this letter ANO proposes to extend the allowed outage time for each unit's EDGs from seven days on ANO-1 and ANO-2 (as proposed by letter 2CAN059501 extending the AOT from three days to seven days with a once per cycle 9

10 day AOT) to include a once per cycle extension of an additional seven days per machine (for a total of 14 days) considering the availability of the AAC diesel generator. The AAC diesel generator is credited for its availability utilizing probabilistic safety analysis techniques.

.Our current philosophy represents a change from the position presented in the August 14, 1992, letter in that the AAC diesel generator is not utilized as a dedicated replacement power t

source for the Class IE EDGs. Credit has been taken for its availability as an alternate AC power supply in the risk evaluation associated with having an EDG out of service.

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j The testing and surveillance requirements for the AAC diesel generator will be conducted in i

accordance with the guidelines of NUMARC 87-00, " Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors," with additional testing as necessary to meet reliability goals. Consistent with Part B.10, this testing includes a l

quarterly test which involves starting the AAC diesel generator and bringing it to operating conditions that are consistent with its function as an AAC power source. Also, once every eighteen months, a timed start (within the time period specified under blackout conditions) j and rated load capacity test will be performed.

Should you have any questions or comments, please contact me.

I Very truly yours, a

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i Dwight C. Mims Director, Nuclear Safety i

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l U. S. NRC November 7,1996 OCAN119606 Page 3 cc:

Mr. Leonard J. Callan Regional Administrator U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 l

NRC Senior Resident Inspector Arkansas Nuclear One P.O. Box 310 London, AR72847 Mr. George Kalman i

NRR Project Manager Region IV/ANO-1 & 2 U. S. Nuclear Regulatory Commission

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NRR Mail Stop 13-H-3 One White Flint North 11555 Rockville Pike Rockville, MD 20852 i

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