ML080100604

Response to Request for Additional Information Regarding Stretch Power Uprate License Amendment Request Response to Question AADB-07-0012

ML080100604
Person / Time
Site:	Millstone
Issue date:	01/10/2008
From:	Hartz L Dominion Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
07-0834
Download: ML080100604 (5)

Text

07-0834 RO 50-423 NPF-49

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10, 2008 Dominion Nuclear Connecticut, Inc.

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\\X'd)\\ddress: www.dom.com January U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MO 20852-2378 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 AADB-07-0012 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 and November 27, 2007 letters.

ONC responded to the RAls in letters dated November 19, 2007 (Serial No. 07-0751) and December 17, 2007 (Serial No. 07-0499).

The NRC staff forwarded an additional RAI in a December 14, 2007 letter.

The response to question AADB-07-0012 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,

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Leslie N. Hartz '-'"U Vice President - Nuclear Support Services COMMONWEALTH OF VIRGINIA COUNTY OF HENRICO

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VICKI L. HULL Notary PublIc COInmonweatlh of YIIgInIo 1....

CommtIIIOn The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Leslie N.

Hartz, who is Vice President - Nuclear Support Services of Dominion Nuclear Connecticut, Inc. She has affirmed before me that she IS duly authorized to execute and file the foregoing document in behalf of that Company, and that the statements in the document are true to the best of her knowledge and belief.

Acknowledged before me this Ie7fIday of

, 2008.

Serial No. 07-0834 Docket No. 50-423 RAI Question AADB-07-0012, Stretch Power Uprate Page 2 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 0-8B1A Rockville, MD 20852-2738 Ms. C. J. Sanders Project Manager U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 0-8B3 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

ATTACHMENT LICENSE AMENDMENT REQUEST STRETCH POWER UPRATE LICENSE AMENDMENT REQUEST RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION RESPONSE TO QUESTION AADB-07-0012 MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC.

Serial No. 07-0834 Docket No. 50-423 Attachment, Page 1 of 2 Accident Dose Branch AADB-07-0012 The staff notes that Table 1.0-1 refers to a modification to the control building for auto initiation of pressurized filtration following control building isolation signal for the purpose of control room dose following a fuel handling accident. The staff notes that section 2.9.2.2.1.5, Control Room, states that: "The control room emergency ventilation system (CREVS) is assumed to be in the filtered recirculation mode of operation within 30 minutes of a fuel handling accident involving a spent fuel assembly. A modification will be developed to implement this assumption."

Please provide additional information describing all planned modifications to the CREVS related to credit taken in the revised dose consequences analyses.

DNe Response Presently, the Control Building inlet and outlet dampers will close, isolating the control building from the outside environment, upon receipt of a Control Building Isolation (CBI) signal.

Following a fuel handling accident (FHA), the CBI signal can be generated manually or from a radiation sensor mounted in the Control Building ventilation inlet plenum. After sixty (60) minutes following the CBI, the operators will manually initiate pressurized filtration and filtered recirculation, i.e.,

starting the Control Room Emergency Ventilation System (CREVS).

The Millstone Power Station 3 (MPS3) Stretch Power Uprate (SPU) FHA analysis requires that the CREVS be operating in filtered recirculation mode within 30 minutes from receipt of a high radiation CBI. While it might be possible to credit operator action to accomplish this, it has been decided to modify the Control Building ventilation system and CREVS to perform this automatically.

The CREVS will be modified to start in the pressurized filtration mode automatically, providing not only pressurized filtration but also filtered recirculation.

The modifications will perform the following:

The Control Building inlet dampers will be changed from their present mode of operation; normally open, fail closed, close on CBI, to normally open, fail open, open on CBI.

The CREVS will receive a signal to automatically start upon receipt of a CBI and the associated dampers will align to the pressurized filtration mode of operation.

The Control Room pressurization system has been removed from the

Serial No. 07-0834 Docket No. 50-423 Attachment, Page 2 of 2 MPS3 Technical Specifications (Ref Amendment No. 232) and is not credited for operation in any accident analysis. The CBI signal to actuate the air bottle outlet control valves will be removed. The system can then be maintained either pressurized or depressurized as plant operations dictates, with manual actuation from the control room, as required.

Various plant process computer inputs and Control Board status lights will be modified to reflect the changed operating modes and control signals described above.