ML20217M374

Forwards RAI Re GL 92-01,Rev 1,Suppl 1, Reactor Vessel Structural Integrity, Issued in May 1995.Response Requested within 90 Days of Receipt of Ltr

ML20217M374
Person / Time
Site:	Calvert Cliffs
Issue date:	04/03/1998
From:	Dromerick A NRC (Affiliation Not Assigned)
To:	Cruse C BALTIMORE GAS & ELECTRIC CO.
References
GL-92-01, GL-92-1, TAC-MA0532, TAC-MA0533, TAC-MA532, TAC-MA533, NUDOCS 9804080086
Download: ML20217M374 (11)

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• - NUCLEAR REGULATORY COMMISSION

' U wasnowoton, o.c. asess. eses April 3, 1998 k**e*

Mr. Charles H. Cruse Vice President - Nuclear Energy Baltimore Gas and Electric Company Calvert Cliffs Nuclear Power Station 1850Calvert Cliffs Parkway Lusby, MD 20657 -

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING REACTOR PRESSURE VESSEL INTEGRITY AT CALVERT CLIFFS NUCLEAR POWER Pl. ANT, UNIT NOS.1 AND 2 (TAC NOS. MA0532 AND MA0533)

Dear Mr. Cruse:

Generic Letter (GL) 92-01, Revision 1, Supplement 1 (GL 92-01, Rev.1, Supp.1), " Reactor Vessel

. Strudural 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 soport any new data pertinent to the analysis of the structural integrity of their RPVs and to assoas the impact of those data on their RPV integrity analyses relative to the requirements of Sedian 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 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 dated August 1,1996, for Calvert Cliffs Nuclear Power Plant, Unit Nos.1 and 2. In this letter we indicated that you had submitted the . requested information and that you indicated that the previously submitted evaluations remained valid. As a result, the NRC concluded that no additional information regarding the structural integrity of your RPV was available at that time. 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 rnay affect previous RPV integrity analyses supplied by licensees with CE fabricated RPVs. In consideration of the data presented in the June 1997 CEOG report, the NRC requests that you

. cordrm that your original response is still correct. The comments in the enclosed request for adelonel information (RAl) should be consioered in the assessment of your original submittal.

7 ff the report does include data that would after your original evaluation 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 RAI 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, por GL 92-01, Rev.1, Supp.- 1, provide a certification that previously submitted evaluations {

remain valid.

. The information provided will be used in updating the Reactor Vessel integrity Data Base. Also, please note that RPV integrity analyses utilizing newly identified data could result in the need for Econes amendments in order to maintain compliance with 10 CFR Part 50.60, 9904090086-990403 DR ADOCK 05000317 a PDR . a NBC RE CEffB COPY

April 3, 1998 C. W. Curse 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 additional license amendments or assessments are necessary, the attached requests that you provide a schedule for such submittals.

If you should have any questions regarding this request, please contact me at (301) 415-3473.

Sincerely, Original Signed by:

Alexander W, Dromerick, Senior Project Manager Project Directorate 1-1 Division of Reactor Projects - 1/11 Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318

Enclosure:

Request for Additional Information cc w/ encl: See next page DISTRIBUTION:

Docket File S. Little A. Hiser PUBLIC A. Dromerick PDI-1 R/F OGC J. Zwolinski ACRS S. Bajwa C, Hehl, Region I DOCUMENT NAME: G:\CC1-2\12 MAO 532.RAI To receive a copy of this document, indicate in the box: "C" = Copy without attachment / enclosure "E" = Copy with c ttachment/ enclosure "N" = No copyn DFFICE PfpFDI-1 0 lE LAzPDI-1 \ \h f l f, D:PDI-1 ,(f f t l l l hAME %fgiWerfek'ilec sLittle AT NM SBajwa id %

DATE 04 4 7/98 04/ W 98 i 04/ % /98 04/ /98 04/ /98

1. Official Record Copy

E April 3, 1998

+ C. W. Curse ' 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.

If you should have any questions regarding this request, please contact me at (301) 415-3473.

Sincerely, Original Signed by:

Alexander W. Dromerick, Senior Project Manager Project Directorate 1-1 Division of Reactor Projects - 1/11 Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318

Enclosure:

Request for Additional ]

information ,

cc w/ encl: See next page DISTRIBUTION Docket File S. Little A. Hiser PUBLIC A. Dromerick PDl-1 R/F OGC J. Zwolinski ACRS S. Bajwa C. Hehl, Region i DOCUMENT NAME: G:\CC1-2\12 MAO 532.RAI To receive a copy of this document, indicate in the box: "C" = Copy without attachment / enclosure "E" = Copy with attachment / enclosure "N" = No copyn 0FflM Mkf0I51 A lE LA PDI 1 Uh f b D PDI-1 ,/f f 2, I l l M1 )

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A i C.'W. Curse 10 CFR 50.61 (PTS), and Appendices G and H to 10 CFR Part 50,~ and to address any potential imped on LTOP limits or PT limits. if additional license amendments or assessments are necessary, the enclosure requests that you provide a schedule for such submittals.

If you should have any questions regarding this request, please contact me at

~ (301) 415-3473.

Sincerely, f

Alexander W. Dromerick, Senior Project Manager Project Directorate 1-1 Division of Reactor Projects -1/ll Office of Nuclear Reactor Regulation Dodet Nos. 50-317 and 50-318 Endoeurs: Request for Additional Information cc Wencl. See next page

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Mr. Charles H. Cruse Baltimore Gas & Electric Company Calvert Cliffs Nuclear Power Plant cc:

President Mr. Joseph H. Walter, Chief Engineer Calvert County Board of Public Service Commission of -

Commissioners Maryland 175 Main Street Engineering Division

(~ Prince Frederick, MD 20676 6 St. Paul Centre Baltimore, MD 21202-6806 James P. Bennett, Esquire Counsel Kristen A. Burger, Esquire Baltimore Gas and Electric Company Maryland People's Counsel P.O. Box 1475 6 St. Paul Centre

.iBaltimore, MD 21203 Suite 2102 Baltimore, MD 21202-1631 Jay E. Silberg, Esquire

• Shaw, Pittman, Potts, and Trowbridge Patncia T. Bimie, Esquire 2300 N Street, NW Co-Director Washington, DC 20037. Maryland Safe Energy Coalition P.O. Box 33111 Mr. Thomas N. Pritchett, Director Baltimore, MD 21218 NRM Calvert Cliffs Nuclear Power Plant Mr. Loren F. Donatelt 1650 Calvert Cliffs Parkway NRC TechnicalTraining Center Lusby, MD 20657-4702 5700 Brainerd Road Chattanooga, TN 37411-4017 Resident inspector U.S. Nuclear Regulatory

Commission P.O. Box 287 St. Leonard, MD 20685 Mr. Richard I. McLean, Manager

' Nuclear Programs Power Plant Research Program Maryland Dept. of Natural Resources Tawes State Office Building, B3 Annapolis,MD 21401 Regional Administrator, Region i U.S. Nuclear Regelstory Commission 475 Allendale Road King of Prussia, PA 19406

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• REQUEST FOR ADDITIONAL INFORMATION REACTOR PRESSURE VESSEL INTEGRITY ,

SaGlietLia Assessment of Best-Estimate Chemistry The staff recently received additionalinformation that may affect the determination 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 Engineenng 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 o~ ycur RPV beltline welds. Based upon this reevaluation, supply the information necessary to completely fill 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 informat. ion 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 with the staff, NEl, and industry representatives en 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 Owr. ors Group Representatives and NEl Regarding Review of Responses to Generic Letter P2-01, 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 th$ 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 c

quali6 cation tests) as being from "one weld" or from multiple welds. . This is an important consideration when :n mean-of-the-means or coil-weighted average approach is determined to be the appropriate method for determining the best-estimate chemistry, if a weld (or welds) were fabncated as wold qualification specimens by the same manufacturer, within a short time span, using similar welding input parameters, and using the s3me 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 wolds) as samples from "one wekf' for the purposes of best-festimate chemistry determination. If information is not available to confirm the aforementioned details, but sufficient evidence exists to reasonably assume the details are the same, the best-G Enclosure

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w 2-estwnste chemistry should ts evaluated both by assuming the data came from "one wel( and by assuming that the da's came from an +;-;+0ix'r: number of " multiple welds". A justification should then he provided for which assumption was chosen when the best-eshmate chemistry was determined.

Section 2.0 Evaluation and Use of Surveillance Data The chemical composition report referenced in Sechon 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 and the surveillance weld,

. the information in these reports may result in the need to revise previous evaluations of RPV integrity (including LTOP setpoints and PT limits) per the requirements of 10 CFR 50.80, 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, Supplement 1, the NRC requests the following:

2. that (1) the information listed in Table 2, Table 3, and the 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 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 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 material in a RPV should be considered in evaluating its Integrity regardless of source 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 embnttlement trend for a particular RPV wold, 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.~

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o 3-Based on the information 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

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 methods documented in Reference 1, provide the technical basis for the adjustment and/or the normalization procedure. If the chemical compositions 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 -

i consistant 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 l (e.g., operating temperature and surveillance data) to verify that the RT, for each vessel beltline material is a bounding value. Regulatory Guide 1.99, Revision 2 desenbos two methods for determining the amount of margin and the chemistry factor used in determining RTc. Position 1.1 describes the use of the Generic Tables in the Regulatory Guide. Position 2.1 describes the use of credible surveillarice data. If the surveillance data are credible, the o, 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 indicate 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 203 , 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 vessel is being assessed, the chemistry factor of the RPV weld can be determined. Note that the adjusted ART, 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 the method for adjusting and/or normalizing the surveillance data when determining the chemistry factor differs from the methods documented in Reference 1, provide the technical basis for the adjustment and/or the normalization procedure.

In a meeting between the staff and industry representatives at the NRC on February 12,1998, an industry representative requested a clarification as to when the ratio procedure should be used to evaluate surveillance data. The ratio procedure is described in the PTS rule and RG 1.99, Revision 2. The ratio procedure is used to adjust the measured value of ARTc to account for differences in the chemical composibon between the surveillance weld and the .

vessel beltline weld., The PTS rule and RG 1.99, Revision 2 indicate that when there is clear

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evidence that the oc.pper and nickel content of the surveillance weld differs from the vessel wold, i.e. differs from the average for the wold wire heat number associated with the vessel ~

weld and the surveillance weld, the ratio procedure must be used.

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4 Sedian 3.0 PTS /PT Limit Evaluation

3. If the limiting material,for your plant changes or if the adjusted reference temperature for the limiting material increases as a result of the above eva'uations, provide the revised RTm value for the limiting materialin accordance with 10 CFR 50.61. In addition, if the adjusted RTa 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.

Reference

1. Memorandum from Keith R. Wichman to Edmund 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 m

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Table 2: Heat xxxx capeuse 10 cu m ] Irradiation Fluence uessved cete used in . )

(inclueng Twnowsture (x10'*n/cm') ART. Assessing Vessel )

source) (*F) (*F) (YorN) 1 1

Table 3:' Heat xxxx Capsule ID Cu M trreciation Fluence Measured Adjusted Predicted (Adjusted.

(including Temperature Factor ARTa ART. ART. ProdM) ART. ,

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

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Attachment 2

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