ML20237D476

Refers to GL 97-01 Issued on 970401 & WOG Response as Documented in TRs WCAP-14901,Rev 0 & WCAP-14902,Rev 0, Submitted on 970725.RAI Encl.Staff Could Not Determine Which of 2 TRs Being Endorsed for Assessment of Vhp Nozzles

ML20237D476
Person / Time
Site:	Wolf Creek
Issue date:	08/20/1998
From:	Thomas K NRC (Affiliation Not Assigned)
To:	Maynard O WOLF CREEK NUCLEAR OPERATING CORP.
References
GL-97-01, GL-97-1, TAC-M98612, NUDOCS 9808260219
Download: ML20237D476 (8)

Text

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8 UNITED STATES s

$ NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 3088HOM August 20, 1998 Mr. Otto L. Maynard President and Chief Executive Officer Wolf Creek Nuclear Operating Corporation Post Office Box 411

< Burlington, Kansas 66839

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION (RAI)- WOLF CREEK i

NUCLEAR OPERATING CORPORATION -WOLF CREEK GENERATING STATION, UNIT 1 (TAC M98612)

Dear Mr. Maynard:

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 L 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

l. 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:

l Reactor Vessel Closure Head Penetration Integrity for the Westinghouse Owners Group."

L The WOG submitted the integrated programs described in WCAP-14901, Revision 0, and WCAP-14902, Revision 0, to the staff on July 25,1997. The staff has reviewed your l responses to GL 97-01, dated April 30,1997, July 24,1997, and January 5,1998, and

, determined by your responses that you ware a member of the WOG and a participant in the WOG integrated program that was developed to address degradation in Westinghouse g designed vessel head penetration (VHP) nozzles, and the staff's requests in GL 97-01. \(

However, the staff could not determine after reviewing your responses which of the two Westinghouse Generic Topical Submittals, WCAP-14901, Revision 0, or WCAP-14902, Revision 0, is being endorsed for the assessment of the VHP nozzles at the Wolf Creek g Generating Station (WCGS). c0 9'

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wwwx emm wyy 9908260219 990820 PDR ADOCK 05000482 P PDR _

4 i Mr. Otto L. Maynard August 20, 1998 l

- The staff requires further information to c3mplete its review of your responses as they relate to )

the WOG's integrated program for assessing VHP nozzles at WOG member plants. The j enclosure to this letter forwards staff's inquiries in the form of a request for additional I information (RAI). The staff re_ quests a response to the RAI within 90 days of the date of this '

l letter, it should be noted that similar staff requests have been issued to other WOG member ,

utilities. As was the staff's 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 WCGS. The staff appreciates the efforts expended with respect to this matter, Sincerely, ,

Original Signed By Kristine M. Thomas, Project Manager  !

Project Directorate IV-2 l Division of Reactor Projects lil/IV Office of Nuclear Reactor Regulation Docket No. 50-482 DISTRIBUTION:

Docket File JHarold, DRPE

Enclosure:

Request for Additional PUBLIC 19ullivan, EMCB Information PDIV-2 Reading ~ OGC  ;

EAdensam ACRS cc w/ encl: See next page WBateman WJohnson, RIV KThomas PGwynn, RIV EPeyton i

DOCUMENT NAME: WC98612.RAI OFC PDIV-2/PM PDIV-2/LA NAME

.m Kmomas onc>

EPe@6n DATE 8/Z/98 - 86 0/98 _

OFFICIAL RECORD COPY L__ .

Mr. Otto L. Maynard August 20, 1998 cc w/ encl:

Jay Silberg, Esq. . Chief Operating Officer Shaw, Pittman, Potts & Trowbridge Wolf Creek Nuclear Operating Corporation 2300 N Street, NW P. O. Box 411 Washington, D.C. 20037 Burlington, Kansas 66839 Regional Administrator, Region IV Supervisor Licensing U.S. Nuclear Regulatory Commission Wolf Creek Nuclear Operating Corporation 611 Ryan Plaza Drive, Suite 1000 P.O. Box 411 Arlington, Texas 76011 Burlington, Kansas 66839 Senior Resident inspector U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Resident inspectors Office P. O. Box 311 8201 NRC Road Burlington, Kansas 66839 Steedman, Missouri 65077-1032 Chief Engineer Utilities Division Kansas Corporation Commission

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1500 SW Arrowhead Road Topeka, Kansas 66604-4027 Office of the Governor State of Kansas Topeka, Kansas 66612 Attorney General Judicial Center 301 S.W.10th 2nd Floor Topeka, Kansas 66612 County Clerk Coffey County Courthouse Burlington, Kansas 66839 Vick L. Cooper, Chief Radiation Control Program Kansas Department of Health and Environment Bureau of Air and Radiation Forbes Field Building 283 Topeka, Kansas 66620 i

Request for Additional Information Regarding Utilities Participating in the Westinghouse Owners Group (WOG) Response to Generic Letter (GL) 97-01 Applicability of the WOG Integrated Program I for Assessing Vessel Head Penetration (VHP) Nozzles in Westinghouse Designed Nuclear Plants to the Plant-specific Responses to GL 97-01 for Participating Member Utilities and Plants in the WOG Relationship and Aoolicabilitv of WCAP-14902. Revision O. to GL 97-01 and the WOG 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 l

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 informs. tion lequests. 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 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 R*sponse to NRC Generic Letter 97-01: Reactor Vessel Closure Head Penetration Integrity for the Westinghouse Owners Group."

The technical content provided in WCAP-14902, Revision 0, is basically the same as that

provided in WCAP-14901, Revision 0.' 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 VHP nozzles 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 VHP nozzles for their facilities according to a probabilistic l methodology that was developed by another vendor of choice. The staff has determined by

! letters dated April 30,1997, July 24,1997, and January 5,1998, that you were a member of the WOG and a participant in the WOG integrated program that was developed to address degradation in Westinghouse designed VHP nozzles, and the staff's requests in GL 97-01.

However, the staff could not determine after reviewing your responses which of the two Westinghouse Generic Topical Submittals, WCAP-14901, Revision 0, or WCAP-14902, Revision 0, is being endorsed for the assessment of the VHP nozzles at the Wolf Creek Nuclear Generating Station (WCGS).

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The staff 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. The staff requests the following information with respect to the content of your responses to GL 97-01, dated April 30,1997, July 24,1997, and January 5,1998, and to the WOG's integrated program for assessing VHP nozzles at WOG member plants:

1. Indicate which Westinghouse Topical Report, WCAP-14901, Revision 0, or WCAP-14902, Revision 0, is being endorsed for the assessment of VHP nozzles at WCGS, and which crack initiation and growth susceptibility model is being used for the assessment of the VHP nozzles at WCGS.

2. Provide the following information if Topical Report WCAP-14901 Revision 0, is being endorsed for the VHP nozzles at WCGS; otherwise skip to information Request 3.

a. In WCAP-14901, Revision 0, WEC did not provide any conclusions as to what the probabilistic failure model woWd lead the WOG to conclude with respect to the assessment of PWSCC in We :-designed vessel head penetrations. With respect to the probabilistic susceptibility model (e.g., probabilistic failure model) provided in WCAP-14901:

(1) 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 WCGS relative to the others.

(2) Describe how the probabilistic failure model in WCAP-14901 for assessing postulated flaws in vessel head penetration nozzles was bench-marked, and provide a list and discussion of the standards the model was bench-marked against.

(3) Provide additional information regarding how the probabilistic failure models in WCAP-14901 will be refined to allow the input of plant-specific inspection data into the model's analysis methodology. l i

(4) Describe how the variability in product forms, material specifications, and j heat treatments used to fabricate each CRDM penetration nozzle at the l WOG member utilities are addressed in the probabilistic crack initiation and growth models described or referenced in Topical Report No. WCAP-14901.

b. Table 1-2 in WCAP-14901 provides a summary of the key tasks in WEC's VHP 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 stillin i 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 l

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i your best estimate when these tasks will be completed by WEC, and describe how these activities relate to and will be used to update the probabilistic susceptibility assessment of VHP nonles at WCGS.

c. In the NEl letters of January 29,1998 (Ref.1), and April 1,1998 (Ref. 2), NEl indicated that inspection plans have been developed for the VHP nonles 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 attemate vendor of choice. The WOG's proposal to inspect the VHP nonles at the Farley Unit 2 and Diablo Canyon Unit 2 plants appears to be based on a composite assessment of the VHP nonles at all WOG member plants. Verify that such a composite ranking assessment has been applied to the evaluation of VHP nonles at WCGS. If composite rankings of the VHP nonles at WOG member plants have been obtained from the composite results of the two models, justify why application of the probabilistic susceptibility model described in WCAP-14901, Revision 0, would yield the same comparable relative rankings of the VHP noules for WCGS as would application of the alternate

' probab listic susceptibility model used by the WOG member plants not subscribing to WCAP-14901, Revision O. Comment on the susceptibility  !

rankings of the VHP nonles at WCGS relative to the susceptibility rankings of the VHP nonles at the Farley Unit 2 and Diablo Canyon Unit 2 plants.

3. Provide the following information only if Topical Report WCAP-14902, Revision 0, is being endorsed for the VHP nonles at your plant.

a. WEC and the WOG did not provide a description of the crack initiation and growth susceptibility model used for the assessment of WEC vessel head penetration (VHP) nonles in plants endorsing WCAP-14902, Revision O.

Provide a description of the crack initiation and growth susceptibility model used for assessment of the VHP nonles at WCGS.

b. In WCAP-14902, Revision 0, WEC did not provide any conclusions as to what l the probabilistic failure model would lead the WOG to conclude with respect to

the assessment of PWSCC in WEC-designed vessel head penetration (VHP) nonles. With respect to the probabilistic susceptibility model (e.g., probabilistic failure model) referenced in WCAP-14902

(1) Provide the susceptibility ranking of WCGS as compiled from the crack initiation and growth analysis of the VHP nonles for WCGS to that compiled for the other WOG member plants for which WCAP-14902, Revision 0,is applicable.

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, 4 (2) Describe how the probabilistic failure (crack initiation and growth) model in used for the assessment of the VHP nozzles at WCGS was bench-marked, and provide a list and discussion of the standards the model  ;

was bench-marked against. l (3) Provide additionalinformation regarding how the probabilistic failure (crack initiation and growth) models for the assessment of VHP nozzles '

at WCGS will be refined to allow the input of plant-specific inspection data into the model's analysis methodology.

(4) Describe how the variability in product forms, material specifications, and I heat treatments used to fabricate each CRDM penetration nozzle at the l WOG member utilities are addressed in the probabilistic crack initiation and growth models described or referenced in Topical Report No. WCAP-14902 Revision 0. I

c. Table 1-2 in WCAP-14902, Revision 0, provides a summary of the key tasks in j WEC's VilP nozzle assessment program. The tables indicate that the tasks for

, (1) evaluation of PWSCC mitigation methods, (2) crack growth data and testing, j and (3) crack initiation characterization studies have not been completed and are i stillin progress. In light of the fact that the probabilistic susceptibility models appear to be dependent in part on PWSCC crack initiation and growth estimates, I provide your best estimate when these tasks will be completed by WEC, and describe how these activities relate to and will be used to update the probabilistic susceptibility assessment of VHP nozzles at WCGS.

d. In the NEl letters of January 29,1998 (Ref.1), and April 1,1998 (Ref. 2), NEl indicated that inspection plans have been developed for the VHP nozzles at the l 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 decided to apply an altemate probabilistic susceptibility model to the assessment of the VHP nozzles at your plant, other WOG member licensees, including the Southem Nuclear Operating Company and the Pacific Gas and Electric l Company, the respective licensees for the Farley units and the Diablo Canyon i units, have selected to apply the susceptibility model described in WCAP-14901, Revision 0, to the assessment of VHP nozzles at their plants. The WOG's t proposal to inspect VHP at Farley Unit 2 and Diablo Canyon Unit 2 appears to be l based on an 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 WCGS. If composite rankings of the VHP nozzles at WOG member plants have been obtained from the composite results of the two models, justify why application of the alternate probabilistic susceptibility model being for the assessment of of VHP nozzles at WCGS would yield the same comparable relative rankings as would application of the probabilistic susceptibility model used by the WOG member plants subscribing to the contents of WCAP-14901, Revision O. Comment on the susceptibility i

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4 rankings of the VHP nozzles at your plant relative to the susceptibility rankings of the VHP nozzles at the Farley Unit 2 and Diablo Canyon Unit 2 plants.

References l 1. Letter from David J. Modeen, Director of Engineering, Nuclear Generation Division, l Nuclear Energy Institute, to Mr. G.C. Lainas, Acting Director, Division of Engineering, l Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission (Untitled),

1 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.

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