ML16343A608
| ML16343A608 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 09/30/1998 |
| From: | Steven Bloom NRC (Affiliation Not Assigned) |
| To: | Rueger G PACIFIC GAS & ELECTRIC CO. |
| References | |
| GL-97-01, GL-97-1, TAC-M98562, TAC-M98563, NUDOCS 9810060369 | |
| Download: ML16343A608 (12) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON> D.C. 20555-0001 September 30, 1998 Mr. Gregory M. Rueger, Senior Vice President and General Manager Pacific Gas and Electric Company Nuclear Power Generation Diablo Canyon Nuclear Power Plant P.O. Box 3 Avila Beach, California 93424
SUBJECT:
GENERIC LETTER (GL) 97-01, "DEGRADATIONOF CRDM/CEDM NOZZLE AND OTHER VESSEL CLOSURE HEAD PENETRATIONS" RESPONSES FOR DIABLOCANYON POWER PLANT UNITNOS.
1 AND 2 (TAC NOS. M98562 AND M98563)
Dear Mr. Rueger:
On April 1, 1997, the staff issued Generic Letter (GL) 97-01, "Degradation of CRDM/CEDM Nozzle and Other Vessel Closure Head Penetrations," to the industry requesting in part that addressees provide a description of the plans to inspect the vessel head penetration nozzles (VHPs) at their respective pressurized water reactor (PWR) designed plants.
With respect to the issuance of the GL, the staff required the addressees to submit an initial response within 30 days of issuance informing the staff of the intent to comply with requested information and a follow-up response within 120 days of issuance containing the technical details to the staffs information requests.
In the discussion section of the GL, the staff stated that "individual licensees may wish to determine their inspection activities based on an integrated industry inspection program...," and indicated that it did not object to individual PWR licensees basing their inspection activities on an integrated industry inspection program.
As a result, the Westinghouse Owners=Group (WOG) determined that it was appropriate for its members to develop a cooperative integrated inspection program in response to GL 97-01.
The WOG program is documented in two topical reports issued by the Westinghouse Electric Corporation (WEC), WCAP-14901, Revision 0, "Background and Methodology for Evaluation of Reactor Vessel Closure Head Penetration Integrity for the Westinghouse Owners Group," and WCAP-14902, Revision 0, "Background Material for Response to NRC Generic Letter 97-01:
Reactor Vessel Closure Head Penetration Integrity for the Westinghouse Owners Group."
'The WOG submitted the integrated programs described in WCAP-14901 and WCAP-14902 to the staff on July 25, 1997.
The staff has reviewed you responses to GL 97-01 dated April 28, 1997, and July 28, 1997, and determined by your responses that you were a member of the WOG and a participant in the WOG integrated program that was developed to address the staffs requests in GL 97-01.
In your letters of April28, 1997 and July 28, 1997, you also indicated that the information in Topical Report WCAP-14901 is applicable with respect to the assessment of VHP nozzles at Diablo Canyon Power Plant, Unit Nos.
1 and 2.
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Mr. Gregory M. Rueger September 30, 1998 The staff has reviewed your responses to GL 97-01 dated April28, 1997 and July 28, 1997, and requires further information to complete its review of your responses as they relate to the WOG's integrated program for assessing VHP nozzles at WOG member plants, and to the contents of Topical Report No. WCAP-14901. The enclosure to this letter forwards the staffs inquiries in the form of a request for additional information (RAI).
The staff requests a response to the RAI within 90 days of the submittal date.
It should be noted that similar staff requests have been issued to other WOG member utilities. As was the staffs position before, the staff encourages you to address these inquiries in an integrated fashion with the WOG and the Nuclear Energy Institute (NEI); however, the staff also requests that you identify any deviations from the WOG's integrated program that may be specific to Diablo Canyon Power Plant, Units 1 and 2. The staff appreciates the efforts expended with respect to this matter.
Ifyou have any questions regarding this matter, please contact me at (301) 415-1313.
Sincerely, Original Signed By Steven D. Bloom, Project Manager Project Directorate IV-2 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket Nos. 50-275 and 50-323
Enclosure:
Request for Additional Information cc w/encl: See next page st%El?HM Docket File PUBLIC PDIV-2 Reading EAdensam WBateman SB!oom EPeyton DKirsch, RIV/WCFO ACRS OGC PGwynn, RIV JHarold TSullivan DOCUMENT NAME: DC98562.RAI OFC NAME DATE PDIV-2/PM S
o 9/X9/98 PDIV-2/LA 9/~/98 OFFICIAL RECORD COPY
4
Mr. Gregory M. Rueger September 30, 1998 cc w/encl:
NRC Resident Inspector Diablo Canyon Nuclear Power Plant clo U.S. Nuclear Regulatory Commission P. O. Box 369 Avila Beach, California 93424 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Harris Tower & Pavillion 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 Dr. Richard Ferguson, Energy Chair Sierra Club California 1100 11th Street, Suite 311 Sacramento, California 95814 Christopher J. Warner, Esq.
Pacific Gas & Electric Company Post Office Box 7442 San Francisco, California 94120 Ms. Nancy Culver San Luis.Obispo Mothers for Peace P. O. Box 164 Pismo Beach, California 93448 Chairman San Luis Obispo County Board of Supervisors Room 370 County Government Center San Luis Obispo, California 93408 Mr. Truman Burns Mr. Robert Kinosian California Public Utilities Commission 505 Van Ness, Room 4102 San Francisco, California 94102 Mr. David H. Oatley, Vice President Diablo Canyon Operations and Plant Manager Diablo Canyon Nuclear Power Plant
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'.O..Box 3 Avila Beach, California 93424 Telegram-Tribune ATTN: Managing Editor 1321 Johnson Ave'nue P.O. Box 112 San Luis Obispo, California 93406 Mr. Steve Hsu Radiologic Health Branch State Department of Health Services Post Office Box 942732 Sacramento, California 94232 Diablo Canyon Independent Safety Committee ATTN: Robert R. Wellington, Esq.
Legal Counsel 857 Cass Street, Suite D Monterey, California 93940
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Request for Additional Information Regarding Utilities Participating in the Westinghouse Owners Group (WOG)
Response
to Generic Letter (GL) 97-01 "Background and Methodology for Evaluation of Reactor Vessel Closure Head Penetration Integrity for the Westinghouse Owners Group" Topical Report No. WCAP-14901, Revision 0 Applicabilityof Topical Report No. WCAP-14901, Revision 0, to the Plant-Specific Responses to GL 97-01 for Participating Member Utilities and Plants in the WOG n
li P-14 1
7-1andt On April 1, 1997, the staff issued Generic Letter (GL) 97-01, "Degradation of CRDM/CEDM Nozzle and Other Vessel Closure Head Penetrations," to the industry requesting in part that addressees provide a description of the plans to inspect the vessel head penetration nozzles (VHPs) at their respective pressurized water. reactor (PWR) designed plants.
With respect to the issuance of the GL, the staff required the addressees to submit an initial response within 30 days of issuance informing the staff of the intent to comply with requested information and a follow-up response within 120 days of issuance containing the technical details to the staff's information requests.
In the discussion section of the GL, the staff stated that "individual licensees may wish to determine their inspection activities based on an integrated industry inspection program...," and indicated that it did not object to individual PWR licensees basing their inspection activities on an integrated industry inspection program.
I As a result, the WOG determined that it was appropriate for its members to develop a cooperative integrated inspection program in response to GL 97-01
~ The WOG program is documented in two topical reports issued by the Westinghouse Electric Corporation (WEC),
WCAP-14901, Revision 0, "Background and Methodology for Evaluation of Reactor Vessel Closure Head Penetration Integrity for the Westinghouse Owners Group," and WCAP-14902, Revision 0, "Background Material for Response to NRC Generic Letter 97-01: Reactor Vessel Closure Head Penetration, Integrity for the Westinghouse Owners Group."
The technical content provided in WCAP-14901, Revision 0, is basically the same as that provided in WCAP-14902. The difference with regard to the reports is that WOG member plants subscribing to the content of WCAP-14901 have opted to rank the susceptibility of their vessel head penetrations according to a probabilistic Weibull analysis method that was developed by WEC.
In contrast, the WOG member plants subscribing to the content of WCAP-14902, Revision 0, have opted to rank the vessel head penetrations for their facilities according to a probabilistic methodology that was developed by another vendor of choice. The staff has determined by letters dated April28, 1997, and July 28, 1997, that you were a member of the WOG and a participant in the WOG integrated program that was developed to address the staffs requests in GL 97-01.
In your, letters dated April28, 1997, and July 28, 1997, you also indicated that the information in WEC Topical Report WCAP-14901 is applicable with respect to the assessment of VHP nozzles at Diablo Canyon Power Plant, Unit Nos.
1 and 2.
The staff has reviewed your responses to GL 97-01, dated April28, 1997 and July 28, 1997, and requires further information to complete its review of your responses as they relate to the WOG's integrated program for assessing VHP nozzles at WOG member plants, and to the contents of Topical Report No. WCAP-14901. The staff requests the following information with respect to the content of your responses to GL 97-01, dated April28, 1997 and July 28, 1997, and to the content of WCAP-14901 as it relates to these responses:
In WCAP-14901, WEC did not provide any conclusions as to what the probabilistic failure model would lead the WOG to conclude with respect to the assessment of PWSCC in WEC-designed vessel head penetrations.
With respect to the probabilistic susceptibility model (e.g., probabilistic failure model) provided in WCAP-14901:
a.
Provide the susceptibility rankings compiled for the WOG member plants for which WCAP-14901 is applicable.
In regard to other WOG member plants to which WCAP-14901 is applicable, include the basis for establishing the ranking of Diablo Canyon Power Plant, Units 1 and 2 relative to the others.
b.
Describe how the probabilistic failure model in WCAP-14901 for assessing postulated flaws in vessel head penetration nozztes was bench-marked and provide a list and discussion of,the standards the model was bench-marked against.
c.
Provide additional information regarding how the probabilistic failure models in WCAP-14901 willbe refined to allow the input of plant-specific inspection data into the model's analysis methodology.
d.
Describe how the variability in product forms, material specifications, and heat treatments used to fabricate each CRDM penetration nozzle at the WOG member utilities are addressed in the probabiiistic crack initiation and growth models described or referenced in Topical Report No. WCAP-14901.
2.
Table 1-2 in WCAP-14901 provides a summary of the key tasks in WEC's vessel head penetration nozzle assessment program.
The table indicates that the Tasks for (1)
Evaluation of PWSCC Mitigation Methods, (2) Crack Growth Data and Testing, and (3)
Crack Initiation Characterization Studies have not been completed and are still in progress.
In light of the fact that the probabilistic susceptibility models appear to be dependent in part on PWSCC crack initiation and growth estimates, provide your best estimate when these tasks willbe completed by WEC, and describe how these activities relate to and will be used to update the probabilistic susceptibility assessment of VHP nozzles at Diablo Canyon Power Plant, Units 1 and 2.
3.
In the NEI letters of January 29, 1998 (Ref. 1), and April 1, 1998 (Ref. 2), NEI indicated that inspection plans have been developed for the VHP nozzles at the Farley Unit 2 plant in the year 2002, and the Diablo Canyon Unit 2 plant in the year 2001, respectively.
The staff has noted that although you have endorsed the probabilistic susceptibility model described in WCAP-14901, Revision 0, other WOG member licensees have endorsed a probabilistic susceptibility model developed by an alternate vendor of choice. The WOG's proposal to
inspect the VHP nozzles at the Farley Unit 2 and Diablo Canyon Unit 2 plants appears to be based on a composite assessment of the VHP nozzles at all WOG member plants. Verify that such a composite ranking assessment has been applied to the evaluation of VHP nozzles at your plants.
Ifcomposite rankings of the VHP nozzles at WOG member plants have been obtained from the composite results of the two models, justifywhy application of the probabilistic susceptibility model described in WCAP-14901, Revision 0, would yield the same comparable relative rankings for the VHP nozzles at the Diablo Canyon Unit 1 and Unit 2 plants as would application of the alternate probabilistic susceptibility model used by the WOG member plants not subscribing to WCAP-14901, Revision 0. Comment on the susceptibility rankings of the VHP nozzles at the Diablo Canyon Unit 1 and Unit 2 plants relative to the susceptibility rankings of the VHP nozzles at other WOG member plants.
Letter from David J. Modeen, Director of Engineering, Nuclear Generation Division, Nuclear Energy Institute, to Mr. G.C. Lainas, Acting Director, Division of Engineering, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission (Untitled), January 19, 1998.
2.
Letter from David J. Modeen, Director of Engineering, Nuclear Generation Division, Nuclear Energy Institute, to Mr. G.C. Lainas, Acting Director, Division of Engineering, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, "
SUBJECT:
Generic Letter 97-01, 'Degradation of Control Rod Drive Mechanism Nozzle and Other Vessel Head Penetrations,'
April 1, 1995.
0