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MONTHYEARML0704401882007-02-12012 February 2007 Inspection and Mitigation of Alloy 600/82/182 Pressurizer Butt Welds Reissuance of January 31, 2007 Letter Project stage: Request ML0715704582007-07-18018 July 2007 Pressurizer Surge, Spray, Safety, and Relief Nozzle Weld Susceptibility to Primary Water Stress Corrosion Cracking Project stage: Other 2007-02-12
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MONTHYEARML24030A7522024-01-30030 January 2024 Technical Specification Bases Pages IR 05000336/20234022024-01-30030 January 2024 Security Baseline Inspection Report 05000336/2023402 and 05000423/2023402 (Cover Letter Only) ML23341A0172024-01-12012 January 2024 Issuance of Amendment No. 288 Revision to Applicability Term for Reactor Coolant System Heatup and Cooldown Pressure-Temperature Limitations Figures IR 05000336/20234402024-01-11011 January 2024 Special Inspection Report 05000336/2023440 and 05000423/2023440 (Cover Letter Only) ML24004A1052024-01-0404 January 2024 Request for Information for a Biennial Problem Identification and Resolution Inspection; Inspection Report 05000336/2024010 & 05000423/2024010 ML23361A0942023-12-21021 December 2023 Response to Request for Additional Information Regarding Proposed License Amendment Request to Revise Technical Specifications for Reactor Core Safety Limits, Fuel Assemblies and Core Operating Limits Report . ML23283A3052023-12-20020 December 2023 Review of Appendix F to DOM-NAF2, Qualification of the Framatome ORFEO-GAIA and ORFEO-NMGRID CHF Correlations in the Dominion Energy VIPRE-D Computer Code (EPID L-2022-LLT-0003) (Nonproprietary) ML23361A0312023-12-20020 December 2023 Intent to Pursue Subsequent License Renewal ML23352A0202023-12-18018 December 2023 Senior Reactor and Reactor Operator Initial License Examinations ML23334A2242023-11-30030 November 2023 Request for Exemption from Enhanced Weapons Firearms Background Checks, and Security Event Notifications Implementation ML23324A4222023-11-20020 November 2023 Reactor Vessel Internals Inspections Aging Management Program Submittal Related to License Renewal Commitment 13 ML23324A4302023-11-20020 November 2023 Alloy 600 Aging Management Program Submittal Related to License Renewal Commitment 15 ML23317A2702023-11-13013 November 2023 Core Operating Limits Report, Cycle 23 IR 05000336/20230032023-11-0606 November 2023 Integrated Inspection Report 05000336/2023003 and 05000423/2023003 ML23298A1652023-10-26026 October 2023 Requalification Program Inspection IR 05000336/20234202023-10-0404 October 2023 Security Inspection Report 05000336/2023420 and 05000423/2023420 ML23230A0502023-10-0202 October 2023 5 of the Quality Assurance Topical Report - Review of Program Changes ML23226A0052023-09-26026 September 2023 Issuance of Amendment No. 287 Supplement to Spent Fuel Pool Criticality Safety Analysis IR 05000245/20230012023-09-19019 September 2023 Safstor Inspection Report 05000245/2023001 IR 05000336/20230102023-09-0808 September 2023 Commercial Grade Dedication Report 05000336/2023010 and 05000423/2023010 IR 05000336/20230052023-08-31031 August 2023 Updated Inspection Plan for Millstone Power Station, Units 2 and 3 (Report 05000336/2023005 and 05000423/2023005) ML23248A2132023-08-30030 August 2023 Response to Request for Additional Information Regarding Proposed License Amendment Request to Revise the Applicability Term for Reactor Coolant System Heatup and Cooldown Pressure-Temperature. ML23242A0142023-08-30030 August 2023 Operator Licensing Examination Approval ML23223A0552023-08-18018 August 2023 Request for Withholding Information from Public Disclosure for License Amendment Request to Revise Technical Specifications for Reactor Core Safety Limits, Fuel Assemblies, and COLR Related to Framatome Gaia Fuel ML23223A0482023-08-18018 August 2023 Request for Withholding Information from Public Disclosure for License Amendment Request to Use Framatome Small Break and Realistic Large Break LOCA Evaluation Methodologies for Establishing COLR Limits IR 05000336/20230022023-08-0909 August 2023 Integrated Inspection Report 05000336/2023002 and 05000423/2023002 ML23188A0432023-07-31031 July 2023 Authorization and Safety Evaluation for Alternative Request No. IR-04-11 ML23208A0922023-07-26026 July 2023 Request for Approval of Appendix F of Fleet Report DOM-NAF-2-P Qualification of Framatome ORFEO-GAIA and OORFE-NMGRID CHF Correlations in the Dominion Energy Vipre-D Computer Code Response ML23188A0202023-07-26026 July 2023 Closeout of Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors ML23207A1102023-07-26026 July 2023 NRC Regulatory Issues Summary 2023-01 Preparation and Scheduling of Operator Licensing Examinations IR 05000336/20234012023-07-17017 July 2023 Material Control and Accounting Program Inspection Report 05000336/2023401 and 05000423/2023401 - (Cover Letter Only) ML23175A0052023-07-12012 July 2023 Alternative Request P-07 for Pump Periodic Verification Testing Program for Containment Recirculation Spray System Pumps ML23193A8562023-06-28028 June 2023 Submittal of Updates to the Final Safety Analysis Reports ML23178A1682023-06-26026 June 2023 2022 Annual Report of Emergency Core Cooling System (ECCS) Model Changes Pursuant to the Requirements of 10 CFR 50.46 ML23153A1732023-06-16016 June 2023 Correction to Amendment Nos. 346 & 286 Millstone, 294 & 277 North Anna, 311 & 311 Surry, and 225 Summer to Revise Technical Specifications to Adopt TSTF-554,Rev Reactor Coolant Leakage Requirement ML23151A0742023-06-12012 June 2023 Review of the Spring 2022 Steam Generator Tube Inspection Report ML23159A2202023-06-0808 June 2023 Associated Independent Spent Fuel Storage Installation Revision to Emergence Plan - Report of Changes IR 07200047/20234012023-06-0808 June 2023 NRC Independent Spent Fuel Storage Installation Security Inspection Report No. 07200047/2023401 2024-01-04
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July 18, 2007 Mr. David A. Christian Sr. Vice President and Chief Nuclear Officer Dominion Nuclear Connecticut Innsbrook Technical Center 5000 Dominion Boulevard Glenn Allen, VA 23060-6711
SUBJECT:
MILLSTONE POWER STATION UNIT 2 - PRESSURIZER SURGE, SPRAY, SAFETY, AND RELIEF NOZZLE WELD SUSCEPTIBILITY TO PRIMARY WATER STRESS CORROSION CRACKING (TAC NO. MD4161)
Dear Mr. Christian:
This letter acknowledges the receipt of information from Dominion Nuclear Connecticut, Inc.
pertaining to the pressurizer surge, spray, safety, and relief nozzle and safe end welds at Millstone Power Station Unit 2 (MPS2).
The discovery, in October 2006, of five circumferential indications in three Alloy 82/182 dissimilar metal (DM) welds on the pressurizer at the Wolf Creek Generating Station (Wolf Creek) raised safety concerns based on the size and location of the indications. At Wolf Creek, three indications were in the pressurizer surge nozzle-to-safe end weld, and two separate indications were in the safety and relief nozzle-to-safe end welds. These findings also indicated that significant concerns might exist with the inspection schedules for addressing the pressurizer weld concerns issued by the industry-sponsored Materials Reliability Program (MRP), in Primary System Piping Butt Weld Inspection and Evaluation Guideline (MRP-139).
The Nuclear Regulatory Commission (NRC) is concerned about the pressurizer surge nozzle-to-safe end weld indications, as this is the first time that multiple circumferential primary water stress-corrosion cracking (PWSCC) indications have been identified in a weld. This condition calls into question the degree of safety margin present in past structural integrity evaluations for flawed DM welds susceptible to PWSCC, since multiple stress-corrosion cracking flaws may grow independently and ultimately grow together, significantly reducing the time from flaw initiation to leakage or rupture.
Based on discussions with the NRC staff, licensees of plants susceptible to this condition have committed to enhanced inspection frequency and reactor coolant system leakage monitoring until actions to mitigate the potential of PWSCC in the affected welds have been completed.
In your letter dated February 12, 2007 (Agencywide Documents Access and Management System Accession Number ML070440188), you stated that the pressurizer at MPS2 has been replaced. The new pressurizer utilizes stainless steel nozzle safe ends and weld material that are resistant to stress corrosion cracking. As a result, your response adequately addresses the concerns that the NRC has at this time regarding PWSCC susceptibility of these welds.
D. Christian This completes the NRC staff efforts on TAC No. MD4161 for the review associated with this issue. If you have any questions regarding this matter, please contact the MPS2 Project Manager, John Hughey at 301-415-3204.
Sincerely,
/ra/
Catherine Haney, Director Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-336 cc: See next page
ML071570458 OFFICE CPNB LPL1-2/PM LPL1-2/PM LPL1-2/LA NAME TLupold GEMiller JHughey RSola DATE 07/16/07 06/06/07 06/06/07 06/08/07 OFFICE LPL1-2/BC CPNB/BC DORL/D NAME HChernoff TChan CHaney DATE 07/12/07 07/16/07 07/18/07 Millstone Power Station, Unit No. 2 cc:
Lillian M. Cuoco, Esquire Mr. J. W. "Bill" Sheehan Senior Counsel Co-Chair NEAC Dominion Resources Services, Inc. 19 Laurel Crest Drive Building 475, 5th Floor Waterford, CT 06385 Rope Ferry Road Waterford, CT 06385 Mr. Evan W. Woollacott Co-Chair Edward L. Wilds, Jr., Ph.D. Nuclear Energy Advisory Council Director, Division of Radiation 128 Terry's Plain Road Department of Environmental Protection Simsbury, CT 06070 79 Elm Street Hartford, CT 06106-5127 Ms. Nancy Burton 147 Cross Highway Regional Administrator, Region I Redding Ridge, CT 00870 U.S. Nuclear Regulatory Commission 475 Allendale Road Mr. Chris L. Funderburk King of Prussia, PA 19406 Director, Nuclear Licensing and Operations Support First Selectmen Dominion Resources Services, Inc.
Town of Waterford Innsbrook Technical Center 15 Rope Ferry Road 5000 Dominion Boulevard Waterford, CT 06385 Glen Allen, VA 23060-6711 Charles Brinkman, Director Mr. David W. Dodson Washington Operations Nuclear Services Licensing Supervisor Westinghouse Electric Company Dominion Nuclear Connecticut, Inc.
12300 Twinbrook Pkwy, Suite 330 Building 475, 5th Floor Rockville, MD 20852 Rope Ferry Road Waterford, CT 06385 Senior Resident Inspector Millstone Power Station Mr. Joseph Roy, c/o U.S. Nuclear Regulatory Commission Director of Operations P.O. Box 513 Massachusetts Municipal Wholesale Niantic, CT 06357 Electric Company Moody Street Mr. J. Alan Price P.O. Box 426 Site Vice President Ludlow, MA 01056 Dominion Nuclear Connecticut, Inc.
Building 475, 5th Floor Rope Ferry Road Waterford, CT 06385