ML20217J752

Forwards Request for Addl Info Re Reactor Pressure Vessel Integrity at Millstone Nuclear Power Station,Unit 2 in Response to GL 92-01,Rev 1,Suppl 1

ML20217J752
Person / Time
Site:	Millstone
Issue date:	04/01/1998
From:	Mcdonald D NRC (Affiliation Not Assigned)
To:	Bowling M NORTHEAST NUCLEAR ENERGY CO.
References
GL-92-01, GL-92-1, MA0553, MA553, NUDOCS 9804060377
Download: ML20217J752 (11)

Text

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n neg p k UNITED STATES g j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 30666 0001

• • • • • p April 1, 1998 #

Mr. Martin L Bowling, Jr.

Recovery Officer- Millstone Unit 2 Northeast Nuclear Energy Company c/o Ms. Patricia A. Loftus Director- Regulatory Affairs P.O. Box 128 Waterford, CT 06385

SUBJECT:

~ REQUEST FOR ADDITIONAL INFORMATION REGARDING REACTOR PRESSURE VESSEL INTEGRITY AT THE MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2 (TAC NO. MA0553)

Dear Mr. Bowling:

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 structural integrity 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 Reaulations (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 July 19,1996, for the Millstone Nuclear Power Station, Unit No. 2. In this letter we 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 plant. 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 integrity 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, I the NRC requests that you provide a response to the enclosed request for additionalinformation (RAl) within 90 days of receipt of this letter. If a question does not apply to your situation, please f

indicate this in your RAI response along with your technical basis and, per GL 92-01, Rev.1, Supp.1, provide a certification that previously submitted evaluations remain valid. , gh}

By letter dated November 13,1997, you submitted a RPV integrity analysis for NRC review. To prevent an impact on plant operation, the NRC plans to proceed with this review based on the data originally submitted unless you resubmit your analysis addressing the information in the attached RAI prior to the NRC completing its tachnical review. If any new data are not included in the on-going review, a revised submittal will be necessary. Please notify the cognizant NRC Project Manager for your plant within 30 days of receipt of this letter if you want the NRC to continue its review of the prior submittal or if you want the NRC to defer review until submittal of a revised analysis addressing the information in the enclosed RAl.

s u b 'J 9904060377 980401 PDR ADOCK 05000336 P PDR

+ p M. L. Bowling -

April 1, 1998 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 license amendments in order to maintain compliance with 10 CFR Part 50.60,10 CFR 50.61

. (PTS), and Appendices G and H to 10 CFR Part 50, and to address any potential impact on LTOP limits or PT limits. If additionallicense amendments or assessments are necessary, the enclosure requests that you provide a schedule for such submittals.

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If you should have any questions regarding this request, please contact me at (301) 415-1408.

Sincerely, Original signed by: j

(

Daniel G. Mcdonald Jr., Senior Project Manager i Special Projects Office - Licensing Office of Nuclear Reactor Regulation Docket No. 50-336

Enclosures:

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M. L. Bowling 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 license amendments in order to maintain compliance with 10 CFR Part 50.60,10 CFR 50.61 (PTS), and Appendices G and H to 10 CFR Part 50, and to address any potential impact on LTOP limits or PT limits. If additionallicense 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) 415-1408.

Sincerely,

.0 _- L Daniel G. Mcdonald Jr., Senior Project Manager Special Projects Office - Licensing Office of Nuclear Reactor Regulation Docket No. 50-245

Enclosures:

As stated cc w/encis: See next page 1

I

REQUEST FOR ADDITIONAL INFORMATION REACTOR PRESSURE VESSEL INTEGRITY Mll I RTONE NUCLEAR POWER STATION. UNIT 2 DOCKET NO. 50-336 TAC MA0553 Section 1.0. Assessment of Best-Estimate Chemistry The staff recently received additional information that may affect the determination of the best-estimate chemistry composition for your RPV welds or your surveillance weld material. This data was provided by FTl in letters from Mr. Matthew J. DeVan (FTI) to Mr. Barry J. Elliot (NRC) dated June 6,1997 (INS-97-2262), June 19,1997 (INS-97-2450), and July 10,1997 (INS-97-2741). In addition, it is the NRC staffs understanding that an evaluation of this data was provided to members of the B&W Owner's Group, Mr. R. E. Jaquin (Rochester Gas and Electric), and Mr. P.S. Askins (Tennessee Valley Authority) via letter dated June 30,1997 (INS-97-2526).

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 evaluattion 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 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 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 with 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 92-1, 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 i consideration when a 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 beloaure t

determination. If information is not available to GQDfilm the aforementioned details, but sufficient evidence exists to reasonably assume the details are the same, the best-estimate 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 chosen 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 provide information regarding a best estimate value and the source of the data used in estimating the chemical composition of the heat of material. . This~

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permits tho' 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 50.60,10 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, 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 a' re 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 comment.t All surveillance program results for the heats of materialin 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 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 h 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 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 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. I 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 RTc for each vessel beltline material is 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 RTc.

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 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 ARTe are less than the l projected mean from the Tables plus the generic 204, the chemistry factor may be calculated l 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). i 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 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.  ;

i in a meeting between the staff and industry representatives at the NRC on February 12,1998, an l industry representative requested a clarification as to when the ratio procedure should be used to  !

evaluate surveillance data. The ratio procedure is described m the PTS rule and RG 1.99, l Revision 2. The ratio procedure is used to adjust the measured value of ART, to account for l differences in the chemical composition between the surveillance weld and the vessel beltline weld. The PTS rule and RG 1.99, Revision 2 indicate that when there is clear evidence that the copper and. nickel content of the surveillance weld differs from the vessel weld, i.e. differs from the average for the weld wire heat number associated with the vessel weld and the surveillance weld, the ratio procedure must be used.

Section 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 evaluations, provide the revised RTn. value for the limiting material in accordance with 10 CFR 50.61. In addition, if the adjusted RT, 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 0

2. Tables 2,3 - - * - .. ,

I r

1

i.

i . ..

l.

L TABLE 1 Facility:

Vessel Manufacturer:

l Information requested on RPV Weld and/or Limiting Materials RPV Best- Best- EOL ID Assigned Method of Initial RTa o, o, Wold Wire Estimate Estimate Fluence Material Determining (RTag)

Heat W Copper Nickel (x 10*) Chemistry CFA Factor (CF) l (1) or the material identification of the limiting material as requested in Section 1.0 (1.)

(2) determined from tables or from surveillance data Discussion of the Analysis Method and Data Used for Each Weld Wire Heat Weld Wire Heat Discussion l

1 Attachment 1 4

e-Table 2: Heat xxxx Capsule 10 Cu Ni irradiation Fluence Measured Date Used in (including Temperature (x10*n/cm') ART , Assessing Vessel meurce) (*F) ('F) (Y or N)

Table 3: Heat xxxx Capsule ID Cu Ni irradiation Fluern,: ! Measured Adjusted Prodcted (Adjusted -

(includ6ng Temperature Factor ART., ART , ART , Predicted) ART, ,

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

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Attachment 2

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• - Northeast Nuclear Energy Company Millstone Nuclear Power Station Unit 2 cc:

Lillian M. Cuoco, Esquire Mr. F. C. Rothen Senior Nuclear Counsel Vice President - Work Services Northeast Utilities Service Company Northeast Utilities Service Company P. O. Box 270 P. O. Box 128 Hartford, CT 06141-0270 Waterford, CT 06385 Mr. John Buckingham Emest C. Hadley, Esquire Department of Public Utility Control 1040 B Main Street Electric Unit P.O. Box 549 10 Liberty Square West Wareham, MA 02576 New Britain, CT 06051

~ Mr. D. M. Goebel Mr. Kevin T. A. McCarthy, Director Vice President - Nuclear Oversight Monitoring and Radiation Division Northeast Utilities Service Company Department of Environmental Protection P. O. Box 128 79 Elm Street Waterford, CT 06385 Hartford, CT 06106-5127 Mr. David Amerine Regional Administrator, Region i Vice President - Nuclear Engineering U.S. Nuclear Regulatory Commission and Support 475 Allendale Road Northeast Utilities Service Company King of Prussia, PA 19406 P. O. Box 128

• Waterford, CT 06385 First Selectmen Town of Waterford Mr. Allan Johanson, Assistant Director Hall of Records Office of Policy and Management 200 Boston Post Road Policy Development and Planning Waterford, CT 06385 Division 450 Capitol Avenue - MS# 52ERN Mr. Wayne D. Lanning P. O. Box 341441 Deputy Director of inspections Hartford, CT 06134-1441 Special Projects Office 475 Allendale Road Mr. M. H. Brothers King of Prussia, PA 19406-1415 Vice President - Operations Northeast Nuclear Energy Company Charles Brinkman, Manager P.O. Box 128 Washington Neclear Operations Waterford, CT 06385 ABB Combustion Engineering 12300 Twinbrook Pkwy, Suite 330 Mr. J. A. Price Rockville, MD 20852 Unit Director- Millstone Unit 2 Northeast Nuclear Energy Company Senior Resident inspector P.O. Box 128 Millstone Nuclear Power Station Waterford, CT 06385 clo U.S. Nuclear Regulatory Commission P.O. Box 513 Niantic, CT 06357 i

6 Northeast Nuclear Energy Company Millstone Nuclear Power Station Unit 2 oc-Mr. B. D. Kenyon Attomey Nicholas J. Scobbo, Jr.

Chief Nucler Officer- Millstone Ferriter, Scobbo, Caruso, Rodophele, PC Nodheast Nuclear Energy Company 1 Beacon Street,11th Floor P.O. Box 128 Boston, MA 02108 Waterford, CT 06385 Citizens Regulatory Co.Timission ATTN: Ms. Susan Perry Luxton 180 Great Neck Road Waterford, CT 06365 Deborah Katz, President - - - -

Citizens Awareness Network P. O. Box 83 Shelbume Falls, MA 03170 The Honorable Terry Concannon Co-Chair Nuclear Energy Advisory Council Room 4035 Legislative Office Building Capitol Avenue Hartford, CT 06106

[

i Mr. Evan W. Woollacott Co-Chair Nuclear Energy Advisory Council 128 Tony's Plain Road Simsbury, CT 06070 Little Harbor Consultants, Inc.

Millstone -ITPOP Project Office P. O. Box 0630  :

Niantic, CT 06357-0630 Mr. Daniel L. Curry Project Director Parsons Power Group inc.

2675 Morgantown Road Reading, PA 19607 Mr. Don Schopfer Verification Team Manager Sargent & Lundy 55 E. Monroe Street Chicago,IL 60603