ML080100606

Response to Response to Request for Additional Information Regarding Stretch Power Uprate License Amendment Request Response to Questions SCVB-07-0058 and SCVB-07-0059

ML080100606
Person / Time
Site:	Millstone
Issue date:	01/10/2008
From:	Hartz L Dominion, Dominion Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
07-0834F
Download: ML080100606 (6)

Text

January 10, 2008 Dominion Nuclear Connecticut, Inc.

~ I I II II Domin ion Boulevard, G len Allen, Virginia 2 j ()()()

\\\\ ', h Add ress: www.dorn.corn 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.:

min 07-0834F RO 50-423 NPF-49 DO INION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING STRETCH POWER UPRATE LICENSE AMENDMENT REQUEST RESPONSE TO QUESTIONS SCVB-07-0058 AND SCVB-07-0059 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. 07-04508) 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. DNC 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 questions SCV8-07-0058 and SCVB-07-0059 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,

,:~I-f~

Leslie N. Hartz {/

Vice President - Nuclear Support Services COMMONWEALTH OF VIRGINIA COUNTY OF HENRICO 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.

/ 1'17}I Acknowledged before me this..L...LL...:..- day of ~LLJ..!<=='>::'r-- ' 2008.

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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 Serial No. 07-0834F Docket No. 50-423 SPU Ques. SCVB-07-0058 and SCVB-07-0059 Page 2

ATTACHMENT LICENSE AMENDMENT REQUEST STRETCH POWER UPRATE LICENSE A ENDMENT REQUEST RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION RESPONSE TO QUESTIONS SCVB-07-0058 THROUG H SCVB-07-0059 MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC.

Serial No. 07-0834F Docket No. 50-423 Attachment, Page 1 of 3 Containment and Ventilation Branch SCVB-07-0058 LAR Attachment 5, Section 2.7.7.2.3, second paragraph states, liAs a result of SPU, there will only be minor temperature changes in the process fluids contained in these systems. The minor increase in heat loads can be adequately compensated for by the existing automatic temperature controllers within the cooling systems.

Thus no changes are required for the cooling system as a result of SPU."

Please verify that analysis was done for SPU that confirms that there is no impact on the cooling and control capability of the cooling equipment.

Also please explain why there will be a minor temperature change in the process fluids contained in the cooling equipment due to SPU heat load which has resulted in about 1°F increase in the containment bulk operating temperature during normal power operation.

ONC Response Each containment air recirculation cooling coil assembly has an air inlet temperature transmitter, which modulates the assemblies chilled water outlet valves (3CDS-TV47A1B/C) depending on containment temperature.

A calculation was performed to access the effect of changes in fluid temperatures in the reactor coolant system (RCS), main steam system (MSS), feedwater system (FWS) as well as by the RCP electric motors operated at SPU conditions on the containment bulk air temperature.

The increase in heat releases from these sources at SPU conditions in the Containment Building, as shown by this calculation, is extremely small, and will have a negligible impact on the containment bulk air temperature. The containment air recirculation system will continue to perform its design function.

Since the bulk temperature increases by a small amount (Le. characterized as less than 1°F), the increase in heat must be transferred to the chilled water system. There will also be a corresponding minor change in the process fluids as a result of SPU.

SCVB-07-0059 LAR Attachment 5, Section 2.7.7.2.3, first paragraph states, liThe results of the evaluation determined that an increase in the containment bulk air temperature of less than 1°F from current observed level will occur at SPU conditions."

Serial No. 07-0834F Docket No. 50-423 Attachment, Page 2 of 3 Please explain what is "current observed level" and how does it relate to the current licensing basis containment average operating temperature given in FSAR Section 9.4.7.2.3 which states: "Two of the three containment air recirculation unit coolers are required to maintain the containment average temperature below 95°F.

If one unit fails, the remaining two units maintain the average temperature below 95°F during normal operation."

Please explain what the SPU impact on the containment average temperature is during loss of offsite power in reference to FSAR Section 9.4.7.2.3 which states:

"During a loss of offsite power, these unit coolers can operate with emergency power maintaining an average air temperature of the containment below 135°F."

ONe Response The "current observed level" is the current temperature observed in containment, shown on the attached graph, Containment Zones Daily Average Temperature Qtr 2 and Qtr 3 2005, developed from the Electrical Equipment Qualification (EEQ) temperature instrumentation.

The current observed average air temperature is approximately 106°F.

After SPU, the containment average air temperature is expected to increase less than 1°F and will remain well below the technical specification limit of 120°F.

The increase in heat releases from sources at SPU conditions in the Containment Building is small, will have a negligible impact on the Containment Zone Daily Average Temperature, and the containment air recirculation system will continue to perform its design function.

It should be noted that in FSAR Section 9.4 there is the following statement:

"Throughout Section 9.4, design values are used for space temperatures (dry bulb or wet bulb), relative humidity, chilled water temperature, service water temperature, hot water temperature, air flow rate (cfm), differential pressure (dp),

and various cooling/heating water flow (gpm). These values represent nominal values that were used in initial calculations to estimate the heating ventilation and air conditioning (HVAC) systems requirements. Since these are nominal design values, however, actual operating values during plant operations may vary."

Therefore, 95°F is a nominal design value while the actual Containment Zone Daily Average Temperature is approximately 106°F.

As stated above, the Containment Zones Daily Average Temperature has a minimal increase due to SPU.

The SPU Containment Zone Daily Average Temperature at the beginning of the loss of power is essentially the same as the Pre-SPU Containment Zone Daily Average Temperature.

Analysis has shown that for SPU the reactor plant component cooling water (CCP) system inlet and outlet water temperature difference is insignificant so the overall operation of the systems during a loss of offsite power will remain unchanged.

Serial No. 07-0834F Docket No. 50-423 Attachment, Page 3 of 3 Containment Zones Daily Average Temperature Qtr2 & Qtr3 2005

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