ML20206F191
| ML20206F191 | |
| Person / Time | |
|---|---|
| Issue date: | 04/29/1999 |
| From: | Strosnider J NRC (Affiliation Not Assigned) |
| To: | Terry C AFFILIATION NOT ASSIGNED, NIAGARA MOHAWK POWER CORP. |
| Shared Package | |
| ML20137M713 | List: |
| References | |
| TAC-MA3395, NUDOCS 9905060026 | |
| Download: ML20206F191 (6) | |
Text
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i UNITED STATES g
j NUCLEAR REGULATORY COMMISSION o
WASHINGTON, D.C. 20066 4 001
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April 29, 1999 Carl Terry, BWRVIP Chairman Niagara Mohawk Power Company Post Office Box 63 Lycoming, NY 13093
SUBJECT:
STAFF'S COMMENTS ON THE BWR VESSEL AND INTERNALS PROJECT'S RESPONSE TO THE NRC'S REQUEST FOR ADDITIONAL INFORMATION ON THE INSPECTION OF BWR AX1AL SHELL WELDS (TAC NO. MA3395)
Dear Mr. Terry:
By letter dated December 15,1998, you responded to the NRC staff's Reyest for Additional Information (RAI) dated June 8,1998, related to the staff's review of the Electric Power Research Institute's (EPRI) proprietary report TR 105697, "BWR Vessel and Intemals Project, BWR Reactor Pressure Vessel Shell Weld Inspection Recommendations (BWRVIP-05)." This report was submitted to the NRC staff for review by letter dated September 28,1995, and was i
modified and supplemented by letters dated June 24 and October 29,1996, May 16, June 4, June 13, and December 18,1997, and January 13,1998.
The BWRVIP-05 report, as modified and supplemented, provided recommendations for altemative inspection requirements of BWR reactor pressure vessel (RPV) shell welds, and provided a technical basis for these recommended requirements. As modified, the BWRVIP-05 report proposed to reduce the scope of inservice inspections (ISI) of the BWR RPV shell welds from essentially 100 percent of all RPV shell welds to essentially 100 percent of the axial shell welds and eliminate the inspection of all but a few percent of circumferential shell welds.
The staff concluded in its safety evaluation dated July 28,1998, that BWR licensees may request permanent (i.e., for the remaining term of operation under the existing, initial, license) relief from the ISI requirements of 10 CFR 50.55a(g) for the volumetric examination of circumferential shell welds, but that additional analyses of the axial welds needed to be performed.
The NRC staff's June 8,1998, RAI requested that the BWRVIP provide (1) additional i
probabilistic fracture mechanics (PFM) analyses of the axial welds, (2) a risk-informed assessment based on the results of the PFM analyses and the guidance in Regulatory Guide 1.174, and (3) a proposed course of action to ensure vesselintegrity based on the results of the analysis and assessment.
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in reviewing your response to this RAI, the NRC staff does not agree with the BWRVIP's 00 analysis. Specifically, as discussed in the attached NRC staff comments, the method intended
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for use in evaluating the conditional probability of failure (CPF) for the typical 40-year license g
period of a BWR did not provide a CPF value that was appropriato for RPV safety g
assessments. In addition, the NRC staff does not agree with implementation of the methodology within the analysis in that it credits 100 percent inspection of axial we have generally not been perfom d a BWR plants, gg gy a.v gg ENCLOSURE CONTAINS PROPRIETgRY IgORMATION gpp1 LTVo,6 i
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U Ca:1 Terry 2-The NRC staff has scheduled a meeting with the BWRVIP for May 18,1999, at NRC l
Headquarters in Rockville, Maryland to discuss the staff comments and determine the appropriate course of action by the BWRVIP in addressing this issue.
The NRC staff requests that the BWRVIP review the items in the attachment, and contact C.
E. (Gene) Carpenter, Jr., of my staff, at (301) 415-2169, if any further clarification is required.
Sincerely, A#d+u 4 Jack R. Strosnider, Director Division of Engineering Office of Nuclear Reactor Regulation
Enclosure:
As stated cc: See next page l
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Carl Terry The NRC staff has scheduled a meeting with the BWRVIP for May 18,1999, at NRC Headquarters in Rockville,' Maryland to discuss the staff comments and determine the l.
appropriate coursa of action by the BWRVIP in addressing this issue.
The NRC staff requests that the BWRVIP review the items in the attachment, and contact C.
E. (Gene) Carpenter, Jr., of my staff, at (301) 415-2169, if any further clarification is required.
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Jack R. Strosnider, Director Division of Engineering Office of Nuclear Reactor Regulation
Enclosure:
As stated cc: See next page I
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- 4 UN!TED STATES y
j NUCLEAR REGULATORY COMMISSION 2
WASHINGTON, D.C. 30seH001 g
April 29, 1999 Cart Terry, BWRVIP Chairman Niagara Mohawk Power Company Post Office Box 63.
Lycoming, NY 13093
SUBJECT:
STAFF'S COMMENTS ON THE BWR VESSEL AND INTERNALS PROJECT'S RESPONSE TO THE NRC'S REQUEST FOR ADDITIONAL INFORMATION ON THE INSPECTION OF BWR AXIAL SHELL WELDS (TAC NO. MA3395)
Dear Mr. Terry:
By letter dated December 15,1998, you responded to the NRC staff's Request for AJditional Information (RAl) dated June 8,1998, related to the staff's review of the Electric Power Research Institute's (EPRI) proprietary report TR 105697, "BWR Vessel and Intemals Project, BWR Reactor Pressure Vessel Shell Weld Inspection Recommendations (BWRVIP-05)." This report veas submitted to the NRC staff for review by letter dated September 28,1995, and was modified and supplemented by letters dated June 24 and October 29,1996, May 16, June 4, June 13, and December 18,1997, and Janua'y 13,1998.
The BWRVIP-05 report, as modified and supplemented, provided recommendations for attemativa inspection requirements of BWR reactor pressure vessel (RPV) shell welds, and provided a technical basis for these recommended requirements. As modified, the BWRVIP-i 05 report proposed to reduce the scope of inservice inspections (ISI) of the BWR RPV shell welds from essentially 100 percent of all RPV shell welds to essentially 100 percent of the axial shell welds End eliminate the inspection of all but a few percent of circumferential shell welds.
The staff concluded in its safety evaluation dated July 28,1998, that BWR licensees may request permanent (i.e., for the remaining term of operation under the existing, initial, license) relief from the (Si requirements of 10 CFR 50.55a(g) for the volumetric examination of circumferential shell welds, but that additional analyses of the axial welds needed to be f
performed.
The NRC staff's June 8,1998, RAI requested that the BWRVIP provide (1) additional probabliistic fracture mechanics (PFM) analyses of the axial welds, (2) a risk informed assessment based on the results of the PFM analyses and the guidance in Regulatory Guide 1.174, and (3) a proposed course of action to ensure vessel integrity based on the results of the analysis and assessment.
In reviewing your response to this RAI, the NRC staff does not agree with the BWRVIP's analysis. Specifically, as discussed in the attached NRC staff comments, the method intended for use in evaluating the conditional probability of failure (CPF) for the typical 40-year license
. period of a BWR did not provide a CPF value that was appropriate for RPV safety assessments, in addition, the NRC staff does not agree with implementation of the methodology within the analysis in that it credits 100 percent inspection of axial welds, which have generally not been performed at all BWR plants.
ENCLOSURE CONTAINS PROPRIETARY INFORMATION
.~
~
Cad Terry 2-The NRC staff has scheduled a meeting with the BWRVIP for May 18,1999, at NRC Headquarters in Rockville, Maryland to discuss the staff comments and determine the appropriate course of action by the BWRViP in addressing this issue.
The NRC staff requests that the BWRVIP revhw the items in the attachment, and contact C.
E. (Gene) Carpenter, Jr., of my staff, at (301) 415 2169, if any further clarification is required.
Sincerely, Ae4+uYh Jack R. Strosnider, Director Division of Engineering Office of Nuclear Reactor Regulation
Enclosure:
As stated cc: See next page l
l cc:
Karl W. Singer, Executive Chair Steve Lewis, Technical Chairman BWRVIP Assessment Task BWRVIP Assessment Task Tennessee Valley Authority -
Entergy PO Box 2000 P. O. Box 756 Decaltur, AL 35602-2000 Waterloo Road Port Gibson, MS 39150 Bill Eaton, Executive Chair -
Inspection Committee Carl Larsen, Technical Chairman Entergy Operations, Inc.
BWRVIP inspection Task PO Box 756, Waterloo Rd Yankee Atomic Port Gibson, MS 39150-0756 580 Main Street Bolton, MA 01740 H. Lewis Sumner, Executive' Chairman
. BWRVIP Mitigation Task John Wilson, Technical Chairman Southern Nuclear Operating Co.
BWRVIP Mitigation Task WS BIN B051, PO Box 1295 Clinton Power Station, WC T-31C 40 inverness Center Parkway P.O. Box 678 Birmingham, AL 35201 Clinton,IL 61727 Harry P. Salmon, Executive Chairman Vaughn Wagoner, Technical Chairman 4
BWRVIP Integration Task BWRVIP Integration Task New York Power Authority Carolina Power & Light Company 123 Main St., WS 11 D One Hannover Square 901 White Plains, NY 10601-3104 P.O. Box 1551 Raleigh, NC 27612 George T. Jones, Executive Chair BWRVIP Repair Task Bruce McLeod, Technical Chairman Pennsylvania Power & Light, Inc.
BWRVIP Repair Task WS GEN A 61 Southern Nuclear Operating Co.
2 N 9* Street Post Office Box 1295 Allentown, PA 18101-1139 40 inverness Center Parkway Birmingham, AL 35201 Robert Carter, EPRI BWRVIP Assessment Manager Warren Bilanin, EPRI BWRVIP EPRI NDE Center Integration Manager P. O. Box 217097 Raj Pathania, EPRI BWRVIP 1300 W. T. Harris Blvd.
Mitigation Manager Charlotte, NC 28221 Ken Wolfe, EPRI BWRVIP Repair Manager Greg Selby, EPRI BWRVIP Electric Power Research Institute inspection Manager P. O. Box 10412 EPRI NDE Center 3412 Hillview Ave.
P. O. Box 217097 Palo Alto, CA 94303 1300 W. T. Harris Blvd.
Charlotte, NC 28221 James P. Pelletier, BWRVIP Liaison to EPRI Nuclear Power Council Joe Hagen, BWRVIP Vice Chairman Nebraska Public Power District PEPCO Energy Co.
1200 Prospect Avenue MC 62C-3 PO Box 98 965 Chesterbrook Blvd Brownville, NE 68321-0098 l
Wayne, PA 19807-5691
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