ML14325A644

Response to Request for Additional Information Regarding License Amendment Request for Proposed Technical Specification Changes of the Refueling Water Storage Tank Allowable Temperatures

ML14325A644
Person / Time
Site:	Millstone
Issue date:	11/14/2014
From:	Mark D. Sartain Dominion, Dominion Nuclear Connecticut
To:	Document Control Desk, Division of Operating Reactor Licensing
References
Download: ML14325A644 (6)

Text

Dominion Nuclear Connecticut, Inc.

5000 Dominion Boulevard, Glen Allen, VA 23060 ijF Dominion Web Address: www.dom.com November 14, 2014 U.S. Nuclear Regulatory Commission Serial No.14-493 Attention: Document Control Desk NSSL/MLC RO Washington, DC 20555 Docket No. 50-423 License No. NPF-49 DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST FOR PROPOSED TECHNICAL SPECIFICATION CHANGES OF THE REFUELING WATER STORAGE TANK ALLOWABLE TEMPERATURES By letter dated November 6, 2013, Dominion Nuclear Connecticut, Inc. (DNC) submitted a license amendment request (LAR) for Millstone Power Station Unit 3 (MPS3). The proposed amendment would revise Technical Specification (TS) 3/4.5.4, "Refueling Water Storage Tank," and TS 3/4.6.2.1, "Depressurization and Cooling Systems, Containment Quench Spray System," to provide additional operational margin for control of the Refueling Water Storage Tank (RWST) temperature. In an email dated September 8, 2014, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI) to DNC related to the LAR. After a clarification call, the NRC transmitted a revised RAI. DNC agreed to respond to the revised RAI by November 14, 2014.

The attachment to this letter provides DNC's response to the NRC's RAI.

If you have any questions regarding this submittal, please contact Wanda Craft at (804) 273-4687.

Sincerely, Mark D. Sartain Vice President - Nuclear Engineering CRAIG D SLY COMMONWEALTH OF VIRGINIA COUNTY OF HENRICO I Notary Public Commonwealth of Virginia Reg. # 7518653 My Commission Expires December 31,20L4 The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Mark D. Sartain, who is Vice President - Nuclear Engineering of Dominion Nuclear Connecticut, Inc. He has affirmed before me that he 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 his knowledge and belief.

Acknowledged before me this J day of /JVzv',er-._, 2014.

My Commission Expires: I1 1) &

Notary Public A-cc) ý

Serial No.14-493 Docket No. 50-423 Page 2 of 2 Commitments made in this letter: None

Attachment:

Response to Request for Additional Information Regarding License Amendment Request For Proposed Technical Specification Changes Of The Refueling Water Storage Tank Allowable Temperatures cc: U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 M. C. Thadani Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08-B 1 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station Director, Radiation Division Department of Energy and Environmental Protection 79 Elm Street Hartford, CT 06106-5127

Serial No.14-493 Docket No. 50-423 ATTACHMENT RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST FOR PROPOSED TECHNICAL SPECIFICATION CHANGES OF THE REFUELING WATER STORAGE TANK ALLOWABLE TEMPERATURES DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3

Serial No.14-493 Docket No. 50-423 Attachment, Page 1 of 3 By letter dated November 6, 2013, Dominion Nuclear Connecticut, Inc. (DNC) submitted a license amendment request (LAR) for Millstone Power Station Unit 3 (MPS3). The proposed amendment would revise Technical Specification (TS) 3/4.5.4, "Refueling Water Storage Tank," and TS 3/4.6.2.1, "Depressurization and Cooling Systems, Containment Quench Spray System," to provide additional operational margin for control of the Refueling Water Storage Tank (RWST) temperature. In an email dated September 8, 2014, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI) to DNC related to the LAR. After a clarification call, the NRC transmitted a revised RAI. This attachment provides DNC's response to the NRC's revised RAI.

Question 1 Reference 1, Section 3.2, last sentence of last paragraph:

"While not using 1000F, subsequent analyses have been performed which continue to bound the RWST maximum temperature of 73 0F proposed herein."

Pleaseprovide responses to the following:

a. Provide a descriptive summary of the subsequent analyses which were performed following the Stretch Power Uprate (SPU) analysis identified in Reference 3. Confirm that the results of all the subsequent analyses are identified in Enclosure 1 to Attachment 1 of the license amendment request.

b. For clarity, identify other input parameters and assumptions that have been changed subsequent to the SPU Mass and Energy (M&E) release and containment response analyses.

DNC Response

a. The large break loss of coolant accident (LOCA) containment response analyses in the Millstone Unit 3 (MPS3) Final Safety Analysis Report (FSAR) Chapter 6 were revised after the SPU analysis to correct errors in the Westinghouse LOCA mass and energy (M&E) release calculation. The M&E analysis errors were described in a DNC letter dated April 25, 2013 (ML13120A158) for a license amendment to change the Technical Specification 6.8.4.F value for Peak Calculated Containment Internal Pressure. The NRC approved the change to Technical Specification 6.8.4.F as License Amendment No. 259 (ML14073A055).

The current FSAR Chapter 6 LOCA containment analyses have corrected for those errors and changed the input assumption for RWST temperature to the values reported in Enclosure 1 of Attachment 1 of the November 6, 2013 license amendment request in order to offset the effects of the M&E analysis errors.

Serial No.14-493 Docket No. 50-423 Attachment, Page 2 of 3

b. The LOCA mass and energy release analysis provided by Westinghouse through the end of reflood assumed a RWST temperature of 100'F for the emergency core cooling system (ECCS) fluid. The assumption in the Westinghouse analysis has not changed, as identified in Enclosure 1 to Attachment 1 of the license amendment request.

The Dominion GOTHIC containment analysis, which models the RWST fluid for quench spray and for ECCS during the post-reflood phase until containment sump recirculation, modified the SPU assumption from 100°F to a lower value to offset the effects from Westinghouse LOCA M&E analysis errors that are described in a DNC letter dated April 25, 2013. The RWST temperature reduction was the only MPS3 plant input change that has been made to the SPU large break LOCA mass and energy release and containment response analyses. As described in the footnote to Tables 1 and 2 of Enclosure 1 to Attachment 1 of the license amendment request, the lower values still bound the RWST temperature value requested in this license amendment request.

Question 2 The LOCA containment M&E release analysis documented in the SPU application (References 2 and 3) was not based on the presently corrected versions of the computer codes in WCAP-10325-P-A (Reference 4) methodology. Westinghouse has issued Nuclear Safety Advisory Letters (NSALs)-06-6, 5, and 2 reporting errors in the WCAP-10325-P-A methodology and requires containment analyses should be corrected. These specific NSALs have been addressed by other licensees in recent LARs.

Provide a summary of how MPS3 has resolved Nuclear Safety Advisory Letters (NSALs)-06-6, 5, and 2 documenting that the issues discussed have been resolved.

DNC Response The LOCA mass and energy release analyses for the SPU project were completed in 2007 and included corrections for the issues identified in Westinghouse NSAL-06-6, "LOCA Mass and Energy Release Analysis". The current FSAR containment analyses use LOCA mass and energy data that corrected the errors from NSAL-11-5 that were applicable to MPS3. The NSAL-1 1-5 applicable errors for MPS3 were identified in a license amendment request to change the Technical Specification 6.8.4.F value for Peak Calculated Containment Internal Pressure that was submitted to the NRC in a DNC letter dated April 25, 2013 and approved as License Amendment No. 259.

Serial No.14-493 Docket No. 50-423 Attachment, Page 3 of 3 The current FSAR analyses have not been updated to address NSAL-14-2, "Westinghouse Loss-of-Coolant Accident Mass and Energy Release Calculation Issue for Steam Generator Tube Material Properties," which was distributed to MPS3 on April 8, 2014. NSAL-14-2 was applicable to MPS3, in that the analysis of record used material properties for stainless steel instead of Alloy 600, leading to an under-prediction of the initial stored energy in the steam generator tubes. Based on preliminary information, MPS3 expects no impact on the short-term containment peak pressure calculation and a very small effect on the long-term energy release that can be accommodated by margins available in the containment analyses. DNC expects no impact from NSAL 14-2 on the RWST temperature limits proposed in the LAR submitted November 6, 2013. MPS3 is addressing NSAL-14-2 through the corrective action process.

NRC REFERENCES

1. Letter from Dominion to NRC dated November 6, 2013, "Dominion Nuclear Connecticut, Inc. Millstone Power Station Unit 3, Licensee Amendment Request, Proposed Technical Specification Changes of the Refueling Water Storage Tank Allowable Temperatures", (ADAMS Accession Number ML13322A415)

2. Letter from Dominion to NRC, "Dominion Nuclear Connecticut, Inc., Millstone Power Station Unit 3, License Amendment Request, Stretch Power Uprate,"

dated July 13, 2007, (ADAMS Accession Number ML072000386)

3. NRC letter to Dominion dated August 12, 2008, "Millstone Power Station, Unit No. 3, Issuance of Amendment RE: Stretch Power Uprate (TAC No. MD6070),"

(ADAMS Accession Number ML081610585)

4. WCAP-10325-P-A, May 1983 (Proprietary) and WCAP-1 0326-A (Nonproprietary), "Westinghouse LOCA Mass and Energy Release Model for Containment Design, March 1979."