ML20217D467
| ML20217D467 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 04/20/1998 |
| From: | Mcdonald D NRC (Affiliation Not Assigned) |
| To: | Bowling M, Loftus P NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| TAC-MA0553, TAC-MA553, NUDOCS 9804240330 | |
| Download: ML20217D467 (10) | |
Text
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Mr. M:rtin L. Bowling, Jr. April 20, 1998 R:cov ry Officer- Millstons Unit 2
, Northust Nuclur En:rgy Company c/o Ms. Patricia A. Loftus Director- Regulatory Affairs P.O. Box 128 Waterford, CT 06385
SUBJECT:
CORRECTION TO THE APRIL 1,1998, LETTER REQUESTING ADDITIONAL INFORMATION REGARDING REACTOR PRESSURE VESSEL INTEGRITY AT THE MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2 (TAC NO. MA0553) _
Dear Mr. Bowling:
By letter dated April 1,1998, we provided a request for additionalinformation (RAl) relating to reactor pressure vesselintegrity. RAl's were sent to several utilities and, due to an administrative error, an incorrect RAl was included in the April 1,1998, letter for the Millstone Nuclear Power Station, Unit No. 2. The correct RAI for the Millstone Nuclear Power Station, Unit No. 2, is provided as an enclosure to this letter. We request that you discard the initial RAI dated April 1,1998, and replace it with the correct RAI provided with this letter.
We apologize for this error and any inconvenience it may have caused. If you have any questions, please contact me at (301) 415-1408.
Sincerely, 4 ORIGINAL SIGNED BY: j f
Daniel G. Mcdonald Jr., Senior Project Manager Special Projects Office - Licensing Office of Nuclear Reactor Regulation Docket No. 50-336
Enclosure:
As stated cc w/encls: See next page l l
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,,,,,# April 20, 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:
CORRECTION TO THE APRIL 1,1998, LETTER REQUESTING ADDITIONAL j INFORMATION REGARDING REACTOR PRESSURE VESSEL INTEGRITY AT THE MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2 (TAC NO. MA0553)
Dear Mr. Bowling:
By letter dated April 1,1998, we provided a request for additional information (RAl) relating to reactor pressure vessel integrity. RAl's were sent to several utilities and, due to an administrative error, an incorrect RAI was included in the April 1,1998, letter for the Millstone Nuclear Power Station, Unit No. 2. The correct RAI for the Millstone Nuclear Power Station, Unit No. 2, is provided as an enclosure to this letter. We request that you discard the initial RAI dated April 1,1998, and replace it with the correct RAI provided with this letter.
We apologize for this error and any inconvenience it may have caused. If you have any I questions, please contact me at (301) 415-1408.
Sincerely,
- QA il Daniel G. Mcdonald Jr., Senior Project Manager Special Projects Office - Licensing Office of Nuclear Reactor Regulation Docket No. 50-336
Enclosure:
As stated cc w/encis: See next page
Northeast Nuclear Energy Company Millstone Nuclear Power Station Unit 2 cc:
Ullian 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 060M )
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 Adminiscator, Region l 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 cf 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 Nuclear 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 c/o U.S. Nuclear Regulatory Commission P.O. Box 513 Niantic, CT 06357
Northsast Nuclar Energy Company Millstone Nuclear Power Station l Unit 2 cc:
Mr. B. D. Kenyon Attomey Nicholas J. Scobbo, Jr.
Chief Nucler Officer- Millstone Ferriter, Scobbo, Caruso, Rodophele, PC Northeast Nuclear Energy Company 1 Beacon Street,11th Floor P.O. Box 128 Boston, MA 02108 l Waterford, CT 06385 i
(
- Citizens Regulatory Commission ATTN
- Ms. Susan Perry Luxton i 180 Great Neck Road Waterford, CT 06385 l Deborah Katz, President -
l Citizens Awareness Network
! P. O. Box 83 l l Shelbume Falls, MA 03170 i
l The Honorable Terry Concannon l Co-Chair i Nuclear Energy Advisory Council j
Room 4035 4 Legislative Office Building Capitol Avenue Hartford, CT. 06106 l
Mr. Evan W. Woollacott Co-Chair l Nuclear Energy Advisory Council l 128 Terry's Plain Road l Simsbury, CT 06070 i
Little Harbor Consultants, Inc.
Millstone -ITPOP Project Office P. O. Box 0630 Niantic, CT 06357-0630 Mr. Daniel L. Curry i Project Director l Parsons Power Group Inc.
l 2675 Morgantown Road Reading, PA 19607 Mr. Don Schopfer Verification Team Manager Sargent & Lundy 55 E. Monroe Street Chicago,IL 60603 l
l l
I REQUEST FOR ADDITIONAL INFORMATION REACTOR PRESSURE VESSEL (RPV) INTEGRITY MILLSTONE NUCLEAR POWER STATION. UNIT 2 DOCKET NO. 50-336 TAC NO. MA0553 Section 1.0: 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 Engineering Owners' Group in report j CE NPSD 1039, Revision 02, "Best Estimate Copper and Nickel Values in CE Fabricated l
Reactor Vessel Welds," dated June 1997.
I Based on this information, in accordance with the provisions of Generic Letter 92-01, Revision 1, !
Supplement 1, the NRC requests the following:
- 1. I 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 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 l pressurized thermal shock / pressure and temperature (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 92-01, 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 coil-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 i amples from that weld (or welds) as samples from "one weld" for the purposes of best-estimate chemistry Baclosure L
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-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 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 low-temperature overpressure protection (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. Provide the information listed in Table 2, Table 3, and the chemistry factor from the surveillance data 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 informatien 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 RA! 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 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 tbs emb it*Jement 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 50E4. 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 simila. to that of Table 3. If the method for 1 adjusting and/or normalizing the surveillance data when assessing credibility differ from the j methods documented in Reference 1, provide the technical basis for the adjustment and/or the i i
3-normalization procedure. If the chemical composition of the surveillance weld is not determined in accordance with Referenco 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 an 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 pbnt specific information (e.g., operating temperature and surveillance data) to verify that the RTer for each vessel beltline material is a bounding value. Regulatory Guide (RG) 1.99, Revision 2, describes two methods for determining the amount of margin and ine chemistry factor used in determining RTm1 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 03 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 ARTm7 are less than the projected mean from the Tables plus the generic 20 3, the chemistry factor rnay 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 ARTer 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 NRC Headquarters 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 ARTer to account for 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 nicks! 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 materialincreases as a result of the above evaluations, provide the revised RTp7, value for the limiting materialin accordance with 10 CFR 50.61. In addition, if the adjusted RTm7 value increased, provide a schedule for revising the PT and LTOP limits.
The schedule should ensure that compliance with 10 CFR Part 50 Appendix G is maintained.
l Reference l 1. Memorandum from Keith R. Wichman to Edmund J. Sullivan, " Meeting Summary for i
November 12,1997, Meeting with Owners Group Representatives and NEl Regarding l Review of Responses to Generic Letter 92-01, Revision 1, Supplement 1 Responses,"
dated November 19,1997.
l Attachments:
- 1. Table 1
- 2. Tables 2 and 3 l
l 1
l i
I a l TABLE 1 Facility: i Vessel Manufacturer: I l
Information requested on RPV Weld and/or Limiting Materials l
RPV Best- Best- EOL ID Assigned Method of o, Initial RTuor o3 Weld Wire Ectimate Estimate Fluence Material Determining (RTm7p)
Heat W Copper Nickel (x 10'D Chemistry CFA Factor (CF)
(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 Attachmert 1 r
e Table 2: Heat xxxx Capsule ID Cu NI Irradiation Fluence Measured Data Used in (including Temperature (x10'*n/cm') ART., Assessing Vessel source) (*F) ('F) (Y or N) l J
l Table 3: Heat xxxx Capsule ID Cu NI irradiate Fluence Measured Adjusted Predicted (Adjusted-(including Temperature Factor ART,e, ART,., ART,., Predicted) ART,.,
source) ('F) ('F) (*F) (*F) ('F)
I J
l J
l 1
l l
Attachment 2