ML20203C933

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Forwards Request for Addl Info Re Reactor Pressure Vessel Integrity
ML20203C933
Person / Time
Issue date: 02/05/1998
From: Laina G
NRC (Affiliation Not Assigned)
To: Modeen D
NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT &
References
GL-92-01, GL-92-1, NUDOCS 9802250297
Download: ML20203C933 (13)
v • d • e


Text

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.j NUCLEAR REGULATORY COMMISSION WASHINGTON, o.C. 206 4-0001 g%,

  • ...+ February 5, 1998 David J. Modeen Director of Engineering Nuclear Generation Division Nuclear Engineering Institute 1770 l Street, NW, Suite 400 Washington DC,20006 3708

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING REACTOR PRESSURE VESSEL INTEGRIT(

Dear Mr. Modeen.

The NRC issued Generic Letter (GL) 92 01, Revision 1, Supplement 1 (GL 02-01, Rev.1, Supp.1),

  • Reactor Vessel StructuralIntegrity* in May 1995. The purpose of this GL was to request licensees to identify, collect, and report any new data pertinent to the analysis of the structuralintegrity of their reactor pressure vessels (RPVs) and to assess the impact of those data on their RPV integrity analyses relative to the requirements of Section 50.60 of Title 10 of the Code of Federal Regulah0ns (10 CFR Part 50.60),10 CFR 50.61, Appendices G and H to 10 CFR Part 50 (which encompass pressurized thermal shock (PTS) and upper shelf energy (USE) evaluations), and any potential impact on low temperature over pressure (LTOP) limits or pressure temperature (PT) limits. Alllicensees responded to the letter. Most licensees' responses indicated that additional work was required to respond to all the requests in the letter and that they would provide their final response after completion of additional generic studies, in late 1996 and early 1997, letters were issued to alllicensees acknowledging the receipt of the initial responses to the GL and closing the TAC numbers associated with review of GL 92-01, Rev.1, Supp.1. For most licensees, these letters indicated that a new TAC number would be opened for the review of their final responses when they were received. Following the issuance of these letters, an inspection of Framatome Technologies,Inc. (FTI) was performed by the NRC in May 1997 which focused on obtaining all available RPV weld chemistry data for RPVs fabricated by B&W. As a result of this inspection, additional data were identified which ,

may affect previous RPV integrity analyses supplied by licensees with B&W fabricated RPVs. In J July 1997, the Combustion Engineering Owners Group (CEOG) provided a report with additiona!

RPV weld chemistry data for RPVs fabricated by CE which may affect previous RPV integrity g

analyses supplied by licensees wlth CE fabricated RPVs.

As a follow-up to these letters, the CEOG report, and the NRC inspection of FTl on RPV weld chemistry, the staff plans to open new TACs on certain pressurized-water reactors (PWRs) with CE or B&W fabricated RPVs and request those licensees to provide their final responses to GL 92 01, Supp.1. Enclosed is a typical draft cover letter to a licensee and a draft RAI. Cover letters and RAls will be issued to PWR licensees with CE and B&W fabricated RPVs that have not provided en assessment of the FTl er CEOG data in response to GL 97 01, Rev.1, Supp.1.

The areas covered in the enclosed draft RAI correspond to those specified in GL 92 01, Rev.1, Supp.1. Based on our review of the generic work referenced above, the RAls identify specific issues requested to be addressed in licensee responses. These RAls along with the minutes of

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David J. Modeon 2-the November 12,1997, meeting that were transmitted to you previously are intended to facilitate licenses final responses to the GL The BWR RPV chemistry data submitted in December 1997 in BWRVIP report,

The NRC will be sponsoring a Reactor Vessel Integrity Workshop on February 12 and 13,1998.

The staff will discuss technical issues related to the RAI at the workshop. NEl is encouraged to share the information enclosed with all licensees prior to the workshop. This letter will be placed in the Public Document room.

Your cooperation on thls subject is greatly appreciated, if you have any questions please feel free to contact Barry Elliot of my staff on 415 2709.

Sincerely, t)ltV Gus C. Lainas, Acting Director

< Division of Engineering Office of Nuclear Reactor Regulation

Enclosures:

As stated cc: Kurt Cozens, NEl

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David J. Modeen 2-the November 12,1997, meeting that were transmitted to you previously are intended to ,

facilitate licensee final responses to the GL. l The BWR RPV chemistry data submitted in December 1997 in BWRVIP report, " Update of  ;

Bounding Assessment of BWR/2-6 Reactor Pressure Vessel Integrity lasues (BWRVIP 46)* is under staff review RAls to BWR licensees may be issued in the future.

The NRC will be sponsoring a Reactor Vessel Integrity Workshop on February 12 and 13,1998.

The staff will discuss technicalissues related to the RAI at the workshop. NEl is encouraged to share the information enclosed with alllicensees prior to the workshop. This letter will be placed in the Public Document room. ,

Your cooperation on this subject is greatly appreciated. If you have any questions please feel free to contact Barry Elliot of my staff on 415 2709.

Sincerely, Gus C. Lainas, Acting Director Division of Engineering Office of Nuclear Reactor Regulation

Enclosures:

As stated cc: Kurt Cozens, NEl

- Distribut on:

EMCB R/F

File Center FJMiraglia BWSheron PDR DOCUMENT NAME: G:\HISER\moden.ltr 'Previously concurred INDICATE IN DOX 'C** COPY W10 AT1 ACHMENT/ ENCLOSURE *E"* COPY W/ATTIENCL. *N"*NO COPY OFFICE EMCB.DE EMCB:DE (A)DD:DE (A)BC:EMCB:DE (Asb.DE NAME BElliot* KWichman* EJSullivan* JRStrosnider* ainas DATE 02 /02 /98 02 /02 /98 02 /02 /98 02/ 05/98 !O2 / [ /98 OFFICIAL RECORD COPY

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David J. Modeen 2 the November 12,1997, meeting that were transmitted to you previously are intended to facilitate licensee final responses to the GL The BWR RPV chemistry data submitted in December .J97 in BWRVIP report,' Update of Bounding Assessment of BWR/2 6 Reactor Pressure VesselIntegrity issues (BWRVIP-46)"is under staff review. RAls to BWR licensees may be required in the future.

The NRC will be sponsoring a Reactor Vessel Integrity Workshop on February 12 and 13,1998.

The staff will discuss technical issues related to the RAI at the workshop. NEl is encouraged to shace the information enclosed with all licensees prior to the workshop. This letter will be placed in the Public Document room, Your cooperation on this subject is greatly appreciated, if you have any questions please feel free to contact Barry Elliot of my staff on 415 2709.

Sincerely, Gus C. Lainas, Acting Director Division of Engineering Office of Nuclear Reactor Regulation t

Enclosures:

As stated cc: Kurt Cozens, NEl Distribution:

EMCB R/F File Center SJCollins FJMiraglia BWSheron PDR DOCUMENT NAME: G:\HISER\moden,ltr 'Previously concurred INDICATE IN 90X? *C*= COPY WrO ATTACHMENTIENCLOSURE. *E** COPY WiATTIENCL, *N"*NO COPY OFFICE EMCB:DE EMCB DE (A)BC:EMCB DE (A)DD:DE /( ) (A)D:DE NAME BElliot* KWichman* EJSullivan* JRStrosnide GClainas DATE 02 / 02 /98 02 /02 /98 02 /02 /98 02 / 8 /98 02/ /98 OFFICIAL RECORD COPY V

David J. Modeen 2-Tiie NRC will be sponsoring a Reactor Vessel Integrity Workshop on Feb*Jary 12 and 13,1998. l The staff will discuss technicalissues related to the RIA at the workshop. NElis encouraged to share the information enclosed with all licensees prior to the workshop. This letter will be placed in the Public Document room.

if you have 1y questions please feel free to contact Barry Elliot of my staff on 415 2709.

Sincerely, Gus C. Lainas, Acting Director Division of Engineering Office of Nuclear Reactor Regulation j

Enclosures:

As stated cc: Kurt Cozens, NEl Distribution:

EMCB R/F File Center i SJCollins l FJMiraglia BWSheron PDR

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DOCUMENT NAME: G:\HISER\moden.ltr INDICATE IN BOK "C"* COPY W'O ATTACHMENTTNCLOSURE. *E"* COPY WlATT/ ENCL. *N"=NO COPY Nn ?/ -

OFFICE EMCB DE EMCB.bFq E (A)BC-EMCB DE (A)DD DE (A)D DE NAME BElliot bN 'K VN a EJSullivan (A/ JRStrotnider GClainas DATE  ?*/ M8 'A / IA /98 _

2 / L /98 / /98 / /98 OFFICIAL RECORD COPY

1 DRAFT ATTACHMENT 1 Mr. John Doe Utility Addrett

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING REACTOR PRESSURE VESSEL INTEGRITY AT PLANT (S)

Dear Mr. Doe:

Generic Letter (GL) 92 01, Revision 1, Supplement 1 (GL 92 01, Rev.1, Supp,1),

  • Reactor Vessel Structural Integrity" was issued in May 1995. This GL requested licensees to perform a review of their reactor pressure vessel (RPV) structural integrity assessments in order to identify, collect, and report any new data pertinent to the analysis of the structuralintegrity of their RPVs and to assess the impact of those data on their RPV Integrity analyses relative to the requirements of Section 50.60 of Title 10 of the Code of Federal Regulations (10 CFR Part 50.60),10 CFR 50.61, Appendices G and H to 10 CFR Part 50 (which encompass pressurized thermal shock (PTS) and upper shelf energy (USE) evaluations), and any potential impact on low temperature overpressure (LTOP) limits or pressure temperature (PT) limits.

After reviewing your response, the NRC issued you a letter datedDATE for Plant (s), in this letter we acknowledged receipt of your response, noted that additional RPV information may become available as a result of Owners Group efforts and requested that you provide us with the results of the Owners Groups' programs relative to your plaril We further indicated that a plant specific TAC Number may be opened to review this material. In July 1997, the Combustion Engineering Owners Group (CEOG) provided a report with additional RPV weld chemistry data for RPVs fabricated by CE. This additional RPV weld chemistry data may affect previous RPV :ntegrity analyses supplied by licensees with CE fabricated RPVs. As a follow up to the letter and the CEOG report, and in order to provide a complete response to items 2,3 and 4 of the GL, the NRC requests that you provide a response to the enclosed request for additionalinformation within 90 days of receipt of this letter. If a question does not apply to your situation, please indicate this in your RAI response along with your technical basis and, per GL 92 01, Rev.1, Supp.1, provide a certification that preslously submitted evaluations remain valid.

The informatian provided will be used in updating the Re.ca:or Vessel Integrity Database (RVID).

Also, pleast acte that RPV integrity analyses utilizing nt.w/ identified data could result in the need for license amendments in order to maintain compliance with 10 CFR Part 50.60,10 CFR 50.61 (pressurized thermal shock, PTS), and Appendices G and H to 10 CFR Part 50, and to address any potential impact on low temperature overpressure (LTOP) limits or pressure-temperature (PT) limits. If additionallicense amendments or assessments are necessary, the attached requests that you provide a schedule for such submittals.

DRAFT

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1 If you should have any questions regarding this request, please contact PROJECT MANAGER AT PHONE NUMBER,

! Sincerely,

. W Manager i Enc.losure: As stated t

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REQUEST FOR ADDITIONAL INFORMATION REA.CTOR PRESSURE VESSEL INTEGRITY SEilon 1.0: Assessment of Best Estimate Chemistry The staff recently received additionalinformation that may affect the detemalnation of the best-estimate chemistry composition for your RPV welds or your surveillance weld material. This information was provided to the NRC by the Combustion Engineering Owners' Group in report CE NPSD 1039 Revision 02,'Best Estimate Copper and Nickel Values in CE Fabricated Reactor Vessel Welds,' dated June 1997.

Based on this information, in accordance with the provisions of Generic Letter 92 01, Revision 1, Supplement 1, the NRC requests the following:

1. An evaluation of the information in the reference above and an assessment of its applicability to the determination of the best estimate chemistry for all of your RPV beltline welds. Based upon th:4 reevaluation, supply the information necessary to completely fall out the data requested in Table 1 for each RPV beltline weld material.

Also provide a discussion for the copper and nickel values chosen for each weld wire heat noting what heat specific data were included and excluded from the analysis and the analysis method chosen for determining the best estimate. If the limiting material for your vessel's PTS /PT limits evaluation is not a weld, include the information requested in Table 1 for the limiting material also. Furthermore, you should consider the information provided in Section 2.0 of this RAI on the use of surveillance data when responding.

With respect to your response to this question, the staff notes that some issues regarding the evaluation of the data were discussed in a public meeting between the staff, NEl, and industry representatives on November 12,1997. A summary of this meeting is documented in a meeting summary dated November 19,1997,' Meeting Summary for November 12,1997 Meeting with Owners Group Representatives and NEl Regarding Review of Responses to Generic Letter 92-01, Revision 1, Supplement 1 Responses" (Reference 1). The information in Reference 1 may be useful in helping you to prepare your response.

in addition to the issues discussed in the referenced meeting, you should also consider what method should be used for grouping sets of chemistry data (in particular, those from weld qualification tests) as being from "one weld" or from multiple welds. This is an important consideration when a mean-of the means or coll-weighted average approach is determined to be the appropriate method for determining the best estimate chemistry, if a weld (or welds) were fabricated as weld qualification specimens by the same manufacturer, within a short time span, using similar welding input parameters, and using the same coil (or coils in the case of tandem arc welds) of weld consumables, it may be appropriate to consider all chemistry samples from that weld (or welds) as samples from 'one weld' for the purposes of best estimate chemistry determination. If information is not available to confirm the aforementioned detans, but sufficient evidence exists to reasonably assume the details are the same, the best-estimate 1

1 chemistry should be evaluated both by assuming the data came from 'one weld

  • and by assuming that the data came from an appropriate number of " multiple welds". A justification should then be provided for which assumption was chost,n when the best-estimate chemistry was determined.

Section 2.0; Evaluation and Use of Surveillance Data The chemical composition report referenced in Section 1.0 includes updated chemistry estimates for heats of weld metal. These reports not only provide a suggested best estimate value but also include the source data used in estimating the chemical composition of the heat of material. This permits the determination of the best estimate chemical composition for the various sources of data including surveillance welds. Since the evaluation of surveillance data rely on both the best estimate chemical composition of the RPV weld ar.d the surveillance weld, the information in these reports may result in the need to revise previous evaluations of RPV integrity (!ncluding LTOP setpoints and PT limits) per the requirements of 10 CFR 50.60,10 CFR 50.61, and Appendices G and H to 10 CFR Part 50.

Based on this information and consistent with the provisions of Generic Letter 92-01, Revision 1 Supplernent 1, the NRC requests the following:

2. that (1) the information listed in Table 2, Table 3, and tne chemistry factor from the surveillance data be provided for each heat of material for which surveillance weld data are available and a revision in the RPV integrity analyses (i.e., current licensing basis)is 4

needed or (2) a certification that previously submitted evaluations remain valid. Separate tables should be used for each heat of material addressed. If the limiting material for i your vessel's PTS /PT limits evaluation is not a weld, include the information requested in the tables for the limiting material (if surveillance data are available for this material).

The information discussed in Section 1.0 of this RAI regarding the chemistry reports should be considered in this response along with the following questions and comments.

All surveillance program results for the heats of materialin a RPV should be considered in evaluating its integrity regardless of sour:e per 10 CFR 50.61 (" Surveillance program results means any data that demonstrates the embrittlement trends for the limiting beltline material, including but not limited to data from test reactors or from surveillance programs at other plants with or without surveillance program integrated per 10 CFR 50, Appendix H.'). If any of the data provided in Table 2 are not used in the calculation of the embrittlement trend for a particular RPV weld, the technical basis for not including /using the data should be provided.

When assessing credibility of surveillance data that come from more than one source, adjustments to the surveillance data may be needed to account for differences in the chemical composition and irradiation environment of the different sources consistent with the requirements in 10 CFR 50.61. A method for accounting for these differences is discussed in Reference 1.

Based on the info mation provided in Table 2, the credibility of the surveillance data can be evaluated. The results of these analyses including the slope of the best fit line through the

3 surveillance data can be provided in a format similar to that of Table 3. If the method for  ;

adjusting and/or normalizing the surveillance data when assessing credibility differ from the I methods documented in Reference 1, provide the technical basis for the adjustment and/or the normalization procedure. If the chemical composition of the surveillance weld is not determined in accordance with Reference 1 (i.e., the mean of all chemistry analyses performed on the ,

surveillance weld), provide the technical basis for the estimate.

When determining the chemistry factor for a RPV weld from surveillance data, adjustments to the surveillance data may be needed to account for differences in the chemical composition and irradiation environment between the surveillance specimens and the vessel being assessed consistent with the requirements in 10 CFR 50.61. A method to account for these differences is provided in Reference 1.

In addition,10 CFR 50.61(c)(2) specifies that licensees shall consider plant specific information (e.g., operating temperature and surveillance data) to verify that the Rb for each vessel beltline materialis a bounding value. Regulatory Guide 1.99, Revision 2 describes two methods for determining the amount of margin and the chemistry factor used in determining Rb.

Position 1.1 describes the use of the Generic Tables in the Regulatory Guide. Position 2.1 describes the use of credible surveillance data. If the surveillance data are credible, the q may be reduced in half to calculate the margin term and the chemistry factor is to be determined from the best fit line of the surveillance data, if the evaluation of the surveillance data indicqte that the surveillance data set is not credible and the measured values of ART , are less than the projected mean from the Tables plus the generic 2q, the chemistry factor may be calculated using either Position 1.1 or Position 2.1; however, the full margin term must be applied. The method chosen must bound all the surveillance data to be in compliance with 10 CFR 50.61(c)(2).

Based on the information provided in Table 2 along with the best estimate chemical composition of the heat of material and the irradiation temperature of the plant whose vesselis being assessed, the chemistry factor of the RPV weld can be determined. Note that the adjusted ARbt for a particular surveillance data point may be one value when determining credibility and another value when determining the chemistry factor as a result of the different normalization procedures, if th0 method for adjusting and/or normalizing the surveillance data When determining the chemistry factor differs from the methods documented in Reference 1, l

provide the technical basis for the adjustment and/or the normalization procedure.

Sagtlon 31 PTS /PT Limit Evaluation l

3. If the limiting material for yuur plant changes or if the adjusted reference temperature for the limiting material increases as a result of the above evaluatioa, provide the revised l RTn, value for the limiting material in secordance with 10 CFR 50.61. In addition, if the l adjusted R%, value increased, provide a schedule for revising the PT and LTOP limits.

The schedule should ensure that compliance with 10 CFR 50 Appendix G is maintained.

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0 Reference *

1. Memorandum from Keith R. Wichman to Edrnund J. Sullivan, ' Meeting Summary for November 12,1997 Meeting with Owners Group Representatives and NEl Regarding Review of Responses to Generic Letter 92 01, Revision 1, Supplement 1 Responses",

dated November 19,1997.

Attachments:

1. Table 1
2. Tables 2,3 I

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Facihty-Vessel Manufacturec t Information requested on RPV Weld and/or Limbng Matenais 1

1 1

i RPV Best- Best- EOL;D Assgned Method of Irwhal RT, o, .f .u,___

! Maryn ANT or RTm Weld Wire Estirnate Estwnate Fluence Malenal EL. wm@ i (RTW at EOL l ,

Heat "' ,

Copper Nickel (x 10") C;ei-aidy CFS .l j Factor (CF) (

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  • i (1) or the material idenhficahon of the imhng material as requested in Sechon 1.0 (1.)

4 (2) determined from tables or from surveillance data 4  !

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De_W of the Anahms Method and Data Used for Each Weld Wire Heat 4

Weld Wire Heat Discussion j i

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Table 2: Heat xxxx Capsule ID Cu Ni irrediation Fluence Meetured Date Used in (including Temperature (x10*rvorrf) ARTc Auessing Vessel tource) (*F) ('F) (YorN) l Table 3: Heat xxxx Capsule ID Cu Ni irrediation Fluence Meetured Adjusted Predicted (Adjusted .

(including Temperature Factor ARTc ARic ART , Predicted) ART.,

source) ('F) (*F) ('F) ('F) ('F)

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