ML20249A382
| ML20249A382 | |
| Person / Time | |
|---|---|
| Issue date: | 06/08/1998 |
| From: | Lainas G NRC (Affiliation Not Assigned) |
| To: | Terry C NIAGARA MOHAWK POWER CORP. |
| References | |
| NUDOCS 9806160376 | |
| Download: ML20249A382 (6) | |
Text
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p i UNITED STATES g j NUCLEAR REGULATORY COMMISSION g 8 WAsNINGToN, D.C. 30006 0001
'% * * * * * $ 1 June 8,1998 CarlTerry, BWRVIP Chairman Niagara Mohawk Power Company Post Office Box 63 Lycoming, NY 13093
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION ON BOILING WATER REACTOR AXIAL WELDS RELATED TO STAFF'S REVIEW OF "BWR REACTOR PRESSURE VESSEL SHELL WELD INSPECTIO.N RECOMMENDATIONS" (BWRVIP-05)
Dear Mr. Terry:
By letter dated September 28,1995, as supplemented by letters dated June 24 and October 29,
- 1996, May 16, June 4, June 13, and December 18,1997, and January 13,1998, you submitted the Electric Power Research Institute (EPRI) proprietary report TR-105697, "BWR Vessel and
. Intemals Project [BWRVIP), BWR Reactor Pressure Vessel Shell Weld inspection Recommendations (BWRVIP 05)," for staff review. The BWRVIP-05 report evaluates the current inspection requirements for the reactor pressure vessel shell welds in BWRs, formulates recommendations for altemative inspection requirements, and provides a technical basis for these recommended requirements It initially proposed to reduce the scope of inspection of the e BWR reactor pressure vessel (RPV) welds from essentially 100 percent of all RPV shell welds to I
- 50 percent of the axial welds and zero percent of the circumferential welds; however, as modified, it proposes to perform inservice inspections (ISI) on 100 percent of the RPV axial shell
[
welds, and eliminate me inspection of all but a few percent of circumferential shell welds. g )-
VI In Te.ble 5-1 of your supplemental letter dated January 13,1998, conceming the BWRVIP's respon~e to a staff's request for additional information on the BWRVIP-05 report, the limiting conditional probability of RPV failure, or P(FIE), due to axial welds in boiling water reactors '
, (BWRs) is given as 1.55 x 10? for the Clirnon plant (BWR/6) after 40 years of operation.
Combined with thedBWRVIP's estimate of the overpressure event frequency of 9.5 x 10d/ year for BWR/4 and 9 x 10 / year for BWRs other than BWR/4, the total RPV failure frequency for axial shell we,ds in the limiting plant is 1.4 x 10'8/ year. The staff recognizes there are conservatism -
" in these analyses and the staff requests that the BWRVIP provide a response to the enclosed
[ request for additiontal information.
l Please inform the staff within 30 days of the date of this letter as to your schedule for response
> to this request for additional information.
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! C. Terry Please contact C. E. (Gene) Carpenter, Jr., of my staff at (301) 415-2169 if you have any further questions regarding this subject.
i Sincerely, f.
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Gus C. Lainas, Acting Director Division of Engineering l
Office of Nuclear Reactor Regulation
Enclosure:
As stated i
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C. Terry !
1 Please contact C. E. (Gene) Carpenter, Jr., of my staff at (301) 415-2169 if you have any further l questions regarding this' subject.
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Sincerely, !
Gus C. Lainas. Acting Director Division of Engineering
, Office of Nuclear Reactor Regulation !
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Enclosure:
As stated cc: See next page l
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cc:
George Jones, Executive Chairman Dana Covill, Technical Chairman BWRVIP Assessment Task BWRVIP Assessment Task Pennsylvania Power & Light GPU Nuclear '
A6-1 1 Upper Pond Road l
Two North Ninth Street Parsippany, NJ 07054 Allentown, PA 18101 Joe Hagan, Executive Chairman Carl Larsen, Technical Chairman BWRVIP Inspection Task BWRVIP inspection Task Entergy Yankee Atomic P. O. Box 756 580 Main Street Waterloo Road Bolton, MA 01740 Port Gibson, MS 39150 '
Paul Bemis, Executive Chairman Vaughn Wagoner, Technical Chairman BWRVIP Integration Task BWRVIP Integration Task i Washington Public Power Supply System Carolina Por<er & Light Company !
P. O. Box 968 One Hannover Square 9C1 North Power Plant Loop P.O. Box 1551 Richland, WA 99352-0008 Raleigh, NC 27612 l Lewis Sumner, Executive Chairman John Wilson, Technical Chairman BWRVIP Mitigation Task BWRVIP Mitigation Task i Southern Nuclear Operating Co. Clinton Power Station, M/C T-31C 1 40 inverness Center Parkway P.O. Box 678 Birmingham, AL 35201 Clinton, IL 61727 >
John Blomgren, Executive Chairman Bruce McLeod, Technical Chairman BWRVIP Repair Task BWRVIP Repair Task l Commonwealth Edison Co. Southern Nuclear Operating Co.
1400 Opus Place, Suite 600 Post Office Box 1295 Downers Grove,IL 60615 5701 40 inverness Center Parkway Birmingham, AL 35201 Bill Campbell, BWRVIP Vice Chairman Warren Bilanin, EPRI BWRVIP Carolina Power & Light Integration Manager P. O. Box 1551 Joe Gilman, EPRI BWRVIP i Raleigh, NC 27612 Mitigation Manager Ken Wolfe, EPRI BWRVIP Robert Carter, EPRI BWRVIP Repair Manager Assessment Manager Electric Power Research Institute <
Greg Selby, EPRI BWRVIP P. O. Box 10412 Inspection Manager 3412 Hillview Ave.
EPRI NDE Center Palo Alto, CA 94303 P. O. Box 217097 1300 W. T. Harris Blvd.
Charlotte, NC 28221 2
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REQUESTFOR ADDITIONAL INFORMATION BOILING WATER REACTOR AXIAL WELDS l
- 1. Probabilistic Fracture Mechanics Analvses I Provide the failure frequency using probabilistic fracture mechanics (PFM) analyses of axial welds in boiling water reactors (BWRs). The staff recommends that the following input variables be changed: l
- a. In lieu of the chemical composition values reported by the BWRVIP, the staff recommends use of the actual best estimate chemistry for each weld in each reactor pressure vessel as documented in Combustion Engineering Owners Group Report CE NPSD-1039 Revision 2, unless other values can be justified.
- b. In lieu of the peak neutron fluence, the staff recommends use of a neutron fluence map of the beltline welds.
- c. In lieu of the pressure and temperature used in the BWRVIP-05 report, the staff recommends use of the pressure (1150 psi) and temperature (88'F) of the foreign transient described in the NRC staff's independent assessment of the BWRVIP-05 report (dated August 14,1997).
- d. In lieu of the Marshall flaw density and flaw size distribution used in the BWRVIP-05 report, the staff recommends use of the flaw density (994 flaws /nt) and flaw size distribution based upon the SAFT-UT inspection of the PVRUF vessel (see attached table for cumulative density function of the flaw depth in the base metal).
i 2. Risk-Based Evaluation Provide a risk-based assessment of the impact ofinspection, operating procedures, training, etc., based on the results from above and the guidance in Regulatory Guide 1.174. This Regulatory Guide is being prepared for final publication based upon the draft version in SECY-98 015 and the asa,cciated Staff Requirements Memorandum (SRM) dated May 20,1998 (see attached).
- 3. Proposed Resolutmn Based en the results from 1. and 2., provide your course of action to ensure vesselintegrity.
Attachments: As stated 1
PVRUF Flaw Depth Distribution l
Base Metal Fla epth Cumulative Density Function 0.1575 0.939169 0.1772 0.946579 0.1969 0.953079 0.2165 0.958799 0.2559 0.968219 0.2953 0.975489 0.3543 0.983399 0.4331 0.990129 0.5118 0.994129 l 0.5906 0.996509 0.7874 0.999049 0.984 0.999739 1.181 0.999929 1.575 0.999995 1.969 1.000000 ATTACHMENT 1
- UNITED STATES Cys: Callan
'.*
- Nk" NUCLEAR REGULATORY COMMISSION Thadani
% wAsMINGToN. o.C. 20565-4001 Thompson Norry May 20, 1998 Blaha on*** '
Collins, NRR cerics or TNs l King,RES
- SECRETARY MEMORANDUM TO: L Jose Callan Exe ' rector for Operations l FROM: Joh . o
SUBJECT:
STAFF REQUIREMENTS - SECY-98-015 - FINAL GENERAL REGUI.ATORY GUIDE AND STANDARD REVIEW PLAN FOR l RISK-IPORMED REGULATION OF POWER RE~ACTORS l ' The Commission has approved publication of Regulatory Guide (RG) 1.174 and Standard l Review Plan (SRP) Chapter 19 in the Federal Reglaint using the announcement provided as l
Attachment 1 to the SECY paper. The staff should ensure that the documents reflect Commission direction on policy issues contained in SECY-97-287. The staff should remove l reference to the current licensing basis (CLB) from RG 1.174 and SRP Chapter 19. The staff should replace the term 'CLB' in SECY-98-015 with the term "sicensing basis."
in the SRP Chapter 19, page 19-3. paragraph 1, add " insights" at the end of the first sentence.
(EDO) (RES) (SECY Suspense: 8/aCW98) 9600025 i
6/23/98 9600026 The staff should perform annual reviews of RG 1.174 and SRP Chapter 19 and incorporate experience gained from risk-informed pilot programs when revisions are necessary. The periodic review and update of the ftG and SRP should be tracked in the PRA implementation Plan. L staff should closely monitor industry initiatives to develop processes (e.g., peer review, cross comparison, or certification program) to assess the scope, level of detall, and quality of PRAs used in risk-informed regulatory applications to determine if NRC reviewers can benefit from additional specific guidance in how to assess the quality of PRAs submitted for review. Where appropriate, such measures should be incorporated in future revisions to the RG and SRP. Where problems arise during application of the RG and SRP (such as items 23
- and 42 in Table A-1 of Attachment 6 where stakeholder have concems over the burdens perceived to be associated with monitoring and documentation), the staff should report them to the Commission and, if necessary, seek policy guidance on how to resolve them.
(609) (RES)- (SECY Suspense: 4/80/99) 9800100 6/23/99 SECY NOTE: THIS SRM, SECY-98-015, AND THE COMMISSION VOTING RECORD CONTAINING THE VOTE SHEETS OF ALL COMMISSIONERS WILL BE MADE PUBLICLY AVAILABLE 5 WORKING DAYS FROM THE DATE OF THIS SRM.
r, M D(,OI00 h. ATTACHMENT 2
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cc: Chairman Jackson Commissioner Dicus l Commissioner Diaz Commissioner McGaffigan ,
OGC '
CIO CFO OCA OlG Office Directors, Regions, ACRS, ACNW, ASLBP (via E-Mail)
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