ML080290033
| ML080290033 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/30/2008 |
| From: | John Hughey NRC/NRR/ADRO/DORL/LPLI-2 |
| To: | Christian D Virginia Electric & Power Co (VEPCO) |
| Hughey J, NRR/DORL, 301-415-3204 | |
| References | |
| TAC MD6911 | |
| Download: ML080290033 (5) | |
Text
January 30, 2008 Mr. David A. Christian President and Chief Nuclear Officer Virginia Electric and Power Company Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711
SUBJECT:
MILLSTONE POWER STATION, UNIT NO. 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING EXAMINATION TECHNIQUE OF SELECT CLASS 1 PIPING DISSIMILAR METAL WELDS (TAC NO. MD6911)
Dear Mr. Christian:
By letter to the Nuclear Regulatory Commission (NRC) dated September 27, 2007, Dominion Nuclear Connecticut, Inc. (DNC) submitted the proposed relief request to allow use of a limited one-sided ultrasonic test examination technique. The NRC staff has reviewed the request submitted by DNC and has identified a need for additional information as set forth in the Enclosure.
The draft questions were sent to William Bartron, from your staff, to ensure that the questions were understandable, the regulatory basis for the questions was clear, and to determine if the information was previously docketed. On January 28, 2008, William Bartron indicated that DNC will submit a response by February 19, 2008. Please note that if you do not respond to this letter within this agreed response time or provide an acceptable alternate date in writing, we may reject your application for amendment under the provisions of Title 10 of the Code of Federal Regulations, Section 2.108. If you have any questions, please contact Carleen Sanders at (301) 415-1603.
Sincerely,
/ra/
John D. Hughey, Project Manager Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No.: 50-336
Enclosure:
RAI cc w/encl: See next page
January 30, 2008 Mr. David A. Christian President and Chief Nuclear Officer Virginia Electric and Power Company Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711
SUBJECT:
MILLSTONE POWER STATION, UNIT NO. 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING EXAMINATION TECHNIQUE OF SELECT CLASS 1 PIPING DISSIMILAR METAL WELDS (TAC NO. MD6911)
Dear Mr. Christian:
By letter to the Nuclear Regulatory Commission (NRC) dated September 27, 2007, Dominion Nuclear Connecticut, Inc. (DNC) submitted the proposed relief request to allow use of a limited one-sided ultrasonic test examination technique. The NRC staff has reviewed the request submitted by DNC and has identified a need for additional information as set forth in the Enclosure.
The draft questions were sent to William Bartron, from your staff, to ensure that the questions were understandable, the regulatory basis for the questions was clear, and to determine if the information was previously docketed. On January 28, 2008, William Bartron indicated that DNC will submit a response by February 19, 2008. Please note that if you do not respond to this letter within this agreed response time or provide an acceptable alternate date in writing, we may reject your application for amendment under the provisions of Title 10 of the Code of Federal Regulations, Section 2.108. If you have any questions, please contact Carleen Sanders at (301) 415-1603.
Sincerely, ra John D. Hughey, Project Manager Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No.: 50-336
Enclosure:
RAI cc w/encl: See next page DISTRIBUTION:
PUBLIC LPL1-2 R/F RidsNrrDorlLpl1-2 RidsNrrPMJHughey RidsNrrLAABaxter RidsRgn1MailCenter RidsAcrsAcnwMailCenter RidsOgcRp ADAMS Accession No. ML080290033
- By Memorandum dated OFFICE LPL1-2/GE LPL1-2/PM LPL1-2/LA DCI/CPNB LPL1-2/BC NAME CSanders JHughey (w/comments)
ABaxter TChan*
HChernoff DATE 1/30/08 1/30/08 1/30/08 1/29/08 1/30/08 Official Record Copy
Enclosure MILLSTONE POWER STATION, UNIT NO. 2 RELIEF REQUEST NUMBER 89-64 EXAMINATION TECHNIQUE OF SELECT CLASS 1 PIPING DISSIMILAR METAL WELDS (MD6911)
REQUEST FOR ADDITIONAL INFORMATION In Dominion Nuclear Connecticut, Inc.s (DNC) submittal dated September 27, 2007, Relief Request (RR)-89-64, Section 1.0, Reason for the Request, DNC states These requirements cannot be met because of the cast austenitic stainless steel safe end base material and the weld design configuration.
- 1)
Discuss further the reason(s) why the weld design configuration prevents essentially 100% ultrasonic test (UT) examination coverage.
In Section 3.0 of RR-89-64, Code Requirements for which the Alternative is Requested, DNC states A similar Figure 2-3 is depicted on page 2-2 of the enclosure to this submittal. The required examination volume in Figure 2-3 is shown as C-D-F-E.
2a)
DNCs basis refers to multiple recommended search units and calculated coverage depicted and described in the enclosure. Discuss further how DNCs basis will demonstrate that the proposed one-sided UT examination will provide reasonable assurance that flaws will be detected throughout the entire required examination volume.
2b)
Provide the volume area or amount (%) of cast stainless steel (CASS) material required to be covered as part of the Risk-Informed (RI) Inservice Inspection (ISI) UT examination volume.
In Section 4.0 of RR-89-64, Proposed Alternatives and Supporting Information, DNC states that,... to perform a UT examination of the eight welds in this request with a [Performance Demonstration Initiative] PDI demonstrated procedure from the ferritic pipe or elbow side of the welds; and, perform a bare metal visual examination to provide the needed defense-in-depth in support of the limited UT for axial [Primary Water Storage Corrosion Cracking] PWSCC when UT examination is not performed on these welds during a refueling outage.
3a)
Discuss how the examination personnel are qualified and by what requirements.
3b)
Provide the requirements and criteria that will be used to perform the bare metal visual examination and discuss further how a visual examination on the external surface of the dissimilar metal welds (DMWs) will provide defense-in-depth for the proposed alternative one-sided volumetric examination as visual examination cannot detect subsurface flaws and/or some small surface flaws.
3c)
In the above statement, clarify what is meant by,...when UT examination is not performed on these welds during a refueling outage... This implies that you would use visual examination in lieu of UT, which would be inadequate considering the limitation of the visual examination.
3d)
DNC states, Due to the size of these welds, additional time is needed to determine the appropriate mitigation strategy for these welds in the future. Please discuss your repair strategy should your inspection reveal defects within the Alloy 600 DMW and/or surrounding base metal. Discuss why you require additional time to determine the appropriate mitigation strategy of the subject DMWs.
3e)
Discuss the inspection requirement (frequency) of the subject welds using UT and/or bare-metal visual examination per your RI-ISI program and/or the Materials Reliability Program: Primary System Piping Butt Weld Inspection and Evaluation Guidelines (MRP-139).
3f)
Discuss whether examining the subject welds from the elbow side would provide sufficient coverage given the elbow configuration.
Section 8.0 of RR-89-64, Conclusion, DNC states, The information outlined above and in the enclosure supports the DNC conclusion that a one-sided UT examination from the ferritic pipe or elbow side of the subject welds will provide detection capability for circumferential PWSCC.
Additionally, it provides an increased frequency for bare metal visual examination that will be used to address the limitations for UT examination coverage for the detection of axial PWSCC.
4a)
Discuss further what DNC means by providing an increased frequency for bare metal visual examination.
4b)
Discuss further axial and circumferential PWSCC in terms of the inspection methods.
4c)
DNC states that a one-sided UT examination will provide detection capability for circumferential PWSCC. DNC also states that axial PWSCC may be missed by UT examination. Discuss how the detection capability of the one-sided UT examination will be able to detect axial PWSCC.
- 5)
DNC stated that no UT technique requirements exist to qualify by performance demonstration the UT examination of CASS material. Discuss whether a best effort UT examination will be performed on the CASS per the American Society of Mechanical Engineers Code,Section XI, Appendix III.
- 6)
Discuss the examination history of the subject DMWs.
- 7)
Discuss how approval of this relief request will affect the mitigation of these DMWs to PWSCC.
- 8)
Discuss how approval of this relief request will affect the assumed flaw size, used to size the overlay and used in the fatigue analysis, if weld overlays are to be applied on these DMWs.
- 9.
Discuss how approval of this relief request will affect the inspection categorization of these DMWs under MRP-139.
Millstone Power Station, Unit No. 2 cc:
Lillian M. Cuoco, Esquire Senior Counsel Dominion Resources Services, Inc.
Building 475, 5th Floor Rope Ferry Road Waterford, CT 06385 Edward L. Wilds, Jr., Ph.D.
Director, Division of Radiation Department of Environmental Protection 79 Elm Street Hartford, CT 06106-5127 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 First Selectmen Town of Waterford 15 Rope Ferry Road Waterford, CT 06385 Charles Brinkman, Director Washington Operations Nuclear Services Westinghouse Electric Company 12300 Twinbrook Pkwy, Suite 330 Rockville, MD 20852 Senior Resident Inspector Millstone Power Station c/o U.S. Nuclear Regulatory Commission P.O. Box 513 Niantic, CT 06357 Mr. J. Alan Price Site Vice President Dominion Nuclear Connecticut, Inc.
Building 475, 5th Floor Rope Ferry Road Waterford, CT 06385 Mr. J. W. "Bill" Sheehan Co-Chair NEAC 19 Laurel Crest Drive Waterford, CT 06385 Mr. Evan W. Woollacott Co-Chair Nuclear Energy Advisory Council 128 Terry's Plain Road Simsbury, CT 06070 Ms. Nancy Burton 147 Cross Highway Redding Ridge, CT 00870 Mr. Chris L. Funderburk Director, Nuclear Licensing and Operations Support Dominion Resources Services, Inc.
Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711 Mr. William D. Bartron Licensing Supervisor Dominion Nuclear Connecticut, Inc.
Building 475, 5th Floor Rope Ferry Road Waterford, CT 06385 Mr. Joseph Roy, Director of Operations Massachusetts Municipal Wholesale Electric Company Moody Street P.O. Box 426 Ludlow, MA 01056 Mr. David A. Sommers Dominion Resources Services, Inc.
5000 Dominion Boulevard Glen Allen, VA 23060-6711