ML080220527

Response to Request for Additional Information Regarding Stretch Power Uprate License Amendment Request Response to Question SBPB-07-0105

ML080220527
Person / Time
Site:	Millstone
Issue date:	01/18/2008
From:	Gerald Bichof Dominion, Dominion Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
07-0846B, SBPB-07-0105
Download: ML080220527 (5)

Text

Dominion Nuclear Connecticut, Inc.

<noo Dominion Boulevard, Glen Allen, Virginia 25060 January 18, 2008 Web -vddress: www.dom.com U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2378 Serial No.:

NLOS/MAE:

Docket No.:

License No.:

07-0846B RO 50-423 NPF-49 DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING STRETCH POWER UPRATE LICENSE AMENDMENT REQUEST RESPONSE TO QUESTION SBPB-07-0105 Dominion Nuclear Connecticut, Inc.

(DNC) submitted a

stretch power uprate license amendment request (LAR) for Millstone Power Station Unit 3 (MPS3) in letters dated July 13, 2007 (Serial Nos. 07-0450 and 07-0450A), and supplemented the submittal by letters dated September 12, 2007 (Serial No. 07-0450B) and December 13, 2007 (Serial No. 07-0450C).

The NRC staff forwarded requests for additional information (RAls) in October 29, 2007, November 26, 2007, and December 14, 2007 letters.

DNC responded to the RAls in letters dated November 19, 2007 (Serial No. 07-0751), December 17, 2007 (Serial No. 07-0799),

January 10, 2008 (Serial Nos. 07-0834, 07-0834A, 07-0834C, and 07-0834F), January 11, 2008 (Serial Nos. 07-0834B, 07-0834E, 07-0834G, and 07-0834H), and January 14, 2008 (Serial No. 07-0834D).

The NRC staff forwarded additional RAls in a December 20, 2007 letter.

The response to Question SBPB-07-0105 of this RAI is provided in the attachment to this letter.

The information provided by this letter does not affect the conclusions of the significant hazards consideration discussion in the December 13,2007 DNC letter (Serial No. 07-0450C).

Should you have any questions in regard to this submittal, please contact Ms. Margaret Earle at 804-273-2768.

Sincerely, Gf::!1c~~6 Vice President - Nuclear Engineering COMMONWEALTH OF VIRGINIA COUNTY OF HENRICO MAlQARlT t. IENNE" NotOfY Put>>IIC.3S+30" Commonweatth of VirgInia My Commllllon Expire. Aug 31. 200.

Commitments made in this letter: None Attachment cc:

U.S. Nuclear Regulatory Commission Region I Regional Administrator 475 Allendale Road King of Prussia, PA 19406-1415 Mr. J. G. Lamb U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 0-881A Rockville, MD 20852-2738 Ms. C. J. Sanders Project Manager U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 0-883 Rockville, MD 20852-2738 Mr. S. W. Shaffer NRC Senior Resident Inspector Millstone Power Station Director Bureau of Air Management Monitoring and Radiation Division Department of Environmental Protection 79 Elm Street Hartford, CT 06106-5127 Serial No. 07-08468 Docket No. 50-423 SPU RAI Question S8P8-07-0105 Page 2

Serial No. 07-08468 ATTACHMENT LICENSE AMENDMENT REQUEST STRETCH POWER UPRATE LICENSE AMENDMENT REQUEST RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION RESPONSE TO QUESTION SBPB-07-0105 MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC.

Serial No. 07-08468 Docket No. 50-423 Attachment, Page 1 of 2 Balance-of-Plant Branch SBPB-07-0105 In Attachment 5, Section 2.5.4.3, Reactor Auxiliary Cooling Water System, the licensee states that the following design change was required to the plant component cooling water (CCP) system in order to support SPU conditions:

"A design change to increase the design temperature of the CCP system between the residual heat removal system heat exchangers and the CCP heat exchangers from 150°F to 160°F, and increase the CCP system operating temperature during cooldown modes of operation, will be performed during the SPU implementation." Since SPU conditions will necessitate a change in design conditions, then the resulting change can not be bounded by previous system design conditions.

Provide a description of the design change, the impact on system components, and any physical modifications required to support the change.

ONe Response The revised cooldown analyses for normal cooldown and safety grade cold shutdown show that cooldown can be accomplished by maintaining the maximum operating CCP temperature at the outlet of the Residual Heat Removal (RHR) heat exchangers at 145°F for SPU conditions. The CCP piping for current conditions downstream of the RHR heat exchangers is stress analyzed for 150°F.

In order to provide sufficient margin between maximum operating temperature and the design temperature, as described in Section 2.5.4.2.3, a design change will be performed to increase the CCP piping design temperature from 150°F to 160°F for the CCP return piping and components, including the CCP heat exchanger bypass piping.

The design change includes re-rating the Reactor Plant Component Cooling Water (RPCCW) pumps and valves located in the return piping up to and including the CCP heat exchangers. The proposed design change will evaluate the increase in design temperature and update the code calculations and seismic/design reports as necessary using the applicable ASME code edition of record for each of the components.

The impact of the higher temperature will also be evaluated on the component performance. No physical modifications are anticipated to the pumps, heat exchangers or the valves located in the return piping.

The reanalysis of the return piping and associated pipe supports for the increased maximum operating and design temperatures determined that modification to two of the pipe supports was necessary. With these modifications

Serial No. 07-08468 Docket No. 50-423 Attachment, Page 2 of 2 to the pipe supports, the return piping and associated pipe supports will be able to accommodate the additional loading under SPU conditions.

As a result of the increased maximum operating temperature and design temperature, the high temperature alarm setpoint of the return piping and trip setpoint of the RHR heat exchanger bypass valves will also be increased. Refer to the proposed cooldown related design changes in Table 2.8.4.4-2 of the SPU Licensing Report, which provides the high temperature alarm and trip set points.