GNRO-2013/00076, Supplemental Information to Clarify License Amendment Request for Implementing a 24-Month Fuel Cycle at Grand Gulf Nuclear Station, Unit 1

Supplemental Information to Clarify License Amendment Request for Implementing a 24-Month Fuel Cycle at Grand Gulf Nuclear Station, Unit 1

ML13267A218
Person / Time
Site:	Grand Gulf
Issue date:	09/24/2013
From:	Kevin Mulligan Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GNRO-2013/00076
Download: ML13267A218 (4)

Text

GNRO-201 September 2013 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

SUBJECT:

Supplemental Information to clarify License Amendment Request for Implementing a 24-Month Fuel Cycle at Grand Gulf Nuclear Station, Unit

1. Re: Attachment 5 on Page 21 of 50 for Section 3.6.5.3 Drywell Isolation Valves.

Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 License No. NPF-29

REFERENCE:

1. License Amendment Request for Implementing a 24-Month Fuel Cycle, dated October 2,2012 (Accession No. ML12277A080, GNRO-2012/00096)

Dear Sir or Madam:

On October 2,2012, Entergy OPerations, Inc. (Entergy) submitted a license amendment request (Reference 1) to the U.S. Nuclear Regulatory Commission (NRC) to implement a 24-month fuel cycle at Grand Gulf Nuclear Station (GGNS). Entergy is providing, in the Attachment, supplemental information to clarify the Drywellisolation Valve section found on page 21 of 50 in contained in Reference 1.

This letter contains no new commitments. If you have any questions, please contact Mr.

Christopher Robinson at (601) 437-7326.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 24th day of September, 2013.

Sincerely, KJM/jas next page)

cc:

U.S. Nuclear Regulatory Commission ATTN: Mr. Alan Wang, NRR/DORL (w/2)

Mail Stop OWFN/8 B1 Washington, DC 20555-0001 NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150

Attachment to GNRO-2013/00076 Supplemental Information to Clarify Attachment 5 Drywell Isolation Valve Section of License Amendment Request for Implementing a 24-Month Fuel Cycle, Dated October 2, 2012

Attachment to GNRO-2013/00076 1 1 SR 3.6.5.3.4 actuates to isolation .... Ac*iTit"'l..... on The test of this SR is being increased from once every 18 months to once every 24 months, for a maximum interval of 30 months including the grace period. During the operating cycle, automatic drywell isolation valve isolation times are tested per SR 3.6.5.3.3 in accordance with the In-service Testing Program. Stroke testing of drywell isolation valves tests a significant portion of the circuitry as well as the mechanical function, which will detect failures of this circuitry or failures with valve movement. The frequency of this testing is typically quarterly, unless approved relief has been granted justifying less frequent testing.

A review of the applicable Grand Gulf surveillance history revealed one previous failure of TS SR 3.6.5.3.4.demonstrated that the dr)°Nell isolation valves had one previous failures of the TS function that would have been detected solely by the periodic performance of this SR. l\s such, the impact, if any, on system availability is minimal from the proposed change to a 24 month testing frequency.

On September 24, 2002, thfee...four valves (1 P72-F123. 1P72-F124, 1P72-F126 and 1P45-F274) did not close on an isolation signal. It was determined that relay 1M71 R065, which controls all thfee...four valves, failed to de-energize with its plunger stuck in the energized position. MAl 321408 replaced the Agastat relay and performed satisfactory retesting with all Technical Specifications acceptance criteria met. CR 2002-1936 documented this issue.

The identified failure is unique and not a repetitive failure and is not associated v'Iith any time based failure mechanism GGNS replaces this Agastat relay every 10 years under PMRQ 50024914. GGNS instituted this PMRQ as a result of generic industry concerns/awareness of repetitive Agastat relay failures. The replacement schedule of 10 years is in advance of the environmentally-qualified design life of 14.4 years. Therefore. no age-related failures are expected. Therefore, this failure will have no impact on an extension to a 24 month surveillance interval.

Based on other more frequent testing of the system, and the history of system performance, the impact of this change on safety, if any, is small.