ML101310256

Response to NRC Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems - Commitment Completion Date Change

ML101310256
Person / Time
Site:	Nine Mile Point
Issue date:	05/01/2010
From:	Belcher S Constellation Energy Group, EDF Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GL-08-001
Download: ML101310256 (5)

Text

Sam Belcher P.O. Box 63 Vice President-Nine Mile Point Lycoming, New York 13093 315.349.5200 315.349.1321 Fax CENG a joint venture of Constellation Energy, NINE MILE POINT NUCLEAR STATION May 1, 2010 U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 ATTENTION:

Document Control Desk

SUBJECT:

Nine Mile Point Nuclear Station Unit No. 2; Docket No. 50-410 Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems" -Commitment Completion Date Change

REFERENCE:

(a) Letter from K. J. Poison (NMPNS) to Document Control Desk (NRC), dated October 14, 2008, Nine-Month Response to NRC Generic Letter 2008-01,"Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems" On January 11, 2008, the NRC issued Generic Letter (GL) 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," to address the issue of gas accumulation in the subject systems. The GL requested addressees to submit information to demonstrate that the subject systems are in compliance with the current licensing and design bases and applicable regulatory requirements, and that suitable design, operational, and testing control measures are in place for maintaining this compliance.

By letter dated October 14, 2008 (Reference a), Nine Mile Point Nuclear Station, LLC (NMPNS)provided the nine-month response to GL 2008-01 for both Nine Mile Point Unit 1 (NMP1) and Unit 2 (NMP2). Attachment (2) to Reference (a) provided a list of regulatory comnmitments contained in the correspondence.

One of those commitments was to implement a modification to install a vent valve in the Document Control Desk May 1, 2010 Page 2 NMP2 Low Pressure Core Spray (LPCS) system pump discharge line downstream of the outside containment isolation valve to improve fill and vent activities, with a completion date of "Completion of NMP2 2010 spring refuel outage." The purpose of this letter is to notify the NRC that NMPNS is revising the completion date for installation of a vent valve in the NMP2 LPCS system pump discharge line from "Completion of NMP2 2010 spring refuel outage" to "Completion of NMP2 2012 Refueling Outage." The Attachment to this letter provides the revised regulatory commitment.

Installation of the LPCS system pump discharge line vent valve requires closure of manual blocking valve 2CSL*HCVl 17 to provide positive isolation of the LPCS piping from the reactor vessel. This manual valve is located inside the drywell on the LPCS injection line to the reactor vessel. During the spring 2010 refueling outage, 2CSL*HCV1 17 was found to be incapable of closure, with indications of binding of the valve internals.

Because of its location, repair of this valve would require draining of the LPCS piping by perforning a high risk evolution involving reduced reactor vessel water level, with a potential need for a full core offload and application of a freeze seal on the LPCS piping.With the refueling outage nearing completion and the reactor core fully loaded, NMPNS considers performing such a high risk evolution to repair valve 2CSL*HCV 117 at this time, for the purpose of installing the LPCS system vent valve, to be an undue burden without a corresponding safety benefit.NMPNS believes that the revised commitment completion date is acceptable because the ability of the LPCS system to perform its safety function will not be negatively impacted.

This conclusion is based on the discussion previously provided in Reference (a) demonstrating that the voiding (trapped air) that could exist in the LPCS system piping downstream of the outside containment isolation valve: (1) Is already addressed by an existing water hammer analysis, and (2) Will not affect LPCS system design flow injection rates since significant margin exists in the LOCA analyses.As such, installation of a vent valve in the LPCS system pump discharge line is considered a design enhancement, as previously noted in Reference (a).Confirmatory ultrasonic testing (UT) of the LPCS pump discharge line has been performed prior to completion of the 2010 refueling outage, after the system was filled and vented following completion of required system testing. A small amount of voiding was detected downstream of the outboard containment isolation valve (approximately 1.5 ft 3). Evaluation of this voiding has concluded that the ability of the LPCS system to perform its safety function is not negatively impacted and, therefore, is sufficiently full of water to maintain system operability.

Should you have any questions regarding the information in this submittal, please contact T. F. Syrell, Licensing Director, at (315) 349-5219.Very truly yours, Document Control Desk May 1, 2010 Page 3 STATE OF NEW YORK COUNTY OF OSWEGO: TO WIT: I, Sam Belcher, being duly sworn, state that I am Vice President-Nine Mile Point, and that I am duly authorized to execute and file this response on behalf of Nine Mile Point Nuclear Station, LLC. To the best of my knowledge and belief, the statements contained in this document are true and correct. To the extent that these statements are not based on my personal knowledge, they are based upon information provided by other Nine Mile Point employees and/or consultants.

Such information has been reviewed in accordance with company practice and I believe it to be reliable.Subscribed and sworn before me, a Notary Public in and for the State of New York and County of C)vxr~cja~ao a this i

• day of ItA ,2010.WITNESS my Hand and Notarial Se My Commission Expires: Date Notary PR6lic DENNIS E. VANEEPU"TE Notary Public, State of New York No. 01VA6183401 Qualified in O'nondaga County Certificate Filed in Oswelo Qounty Commission Expires "Q/L;9, SB/DEV

Attachment:

List of Regulatory Commitments cc: S. J. Collins, NRC R. V. Guzman, NRC Resident Inspector, NRC ATTACHMENT LIST OF REGULATORY COMMITMENTS Nine Mile Point Nuclear Station, LLC May 1, 2010 ATTACHMENT LIST OF REGULATORY COMMITMENTS The following table identifies the regulatory commitments in this document.

Any other statements in this submittal represent intended or planned actions. They are provided for information purposes and are not considered to be regulatory commitments.

The listed commitment extends the completion date for the NMP2 modification covered by the previous commitment made in the NMPNS letter dated October 14, 2008.SCHEDULED REGULATORY COMMITMENT COMPLETION DATE NMPNS will implement modifications to install a new vent valve in the NMP2 Completion of NMP2 Low Pressure Core Spray (LPCS) system pump discharge line downstream of the 2012 Refueling outside containment isolation valve to improve fill and vent activities.

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