ML20216D670
| ML20216D670 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 04/09/1998 |
| From: | Hansen A NRC (Affiliation Not Assigned) |
| To: | Jeffery Wood CENTERIOR ENERGY |
| References | |
| GL-92-01, GL-92-1, TAC-MA0540, TAC-MA540, NUDOCS 9804150383 | |
| Download: ML20216D670 (11) | |
Text
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4 UNITED STATES O
g g
NUCLEAR REGULATORY COMMISSION f
WASHINGTON, D.C. 30666-0001 1
- l April 9, 1998 Mr. John K. Wood Vice President - Nuclear, Davis-Besse Centerior Service Company c/o Toledo Edison Company Davis-Besse Nuclear Power Station 5501 North State Route 2 Oak Harbor, OH 43449-9760
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION REGARDING REACTOR PRESSURE VESSEL INTEGRITY - DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO.1 (TAC NO. MA0540)
Dear Mr. Wood:
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 (USE) evaluations), and any potential impact on i
Iow temperature overpressure (LTOP) limits or pressure-temperature (PT) limits.
After reviewing your response, the NRC issued you a letter dated August 13,1996. In this letter the NRC requested, in part, that you provide an assessment of the application of the ratio procedure, as described in Position 2.1 of Regulatory Guide 1.99, Revision 2, to your PT limits curves and LTOP limits.
Subsequent to issuing this letter, the NRC conducted an inspection of Framatome Technologies, Inc. (FTI) in May 1997. This inspection 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 a"Tect previous RPV integrity analyses supplied by licensees with B&W fabricated RPVs.
As a follow-up to the letter and the FTl inspection, 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 (RAl) within 90 days of receipt of this letter. This response should include application of the ratio procedure in the assessment of surveillance data from welds. 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 previously submitted evaluations remain valid.
9804150383 980409 PDR ADOCK 05000346 SC FPJ CBHER CDP)
1 i
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J J. Wood 1,
The information provided will be used in updating the Reactor Vessel Integrity Database
_(RVID). 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 j
impact on LTOP or PT limits. If additional license amendments or assessments are necessary,
-)
the enclosure requests that you provide a schedule for such submittals.
l If you should have any questions regarding this request, please contact me at (301) 415-1390.
j l
Sincerely, Original signed by:
7 Allen G. Hansen, Project Manager l
Project Directorate lil-3 Division of Reactor Projects Ill/IV Office of Nuclear Reactor Regulation Docket No. 50-346
Enclosure:
As Stated f
.cc w/ encl: See next page l
DISTRIBUTION Docket File PUBLIC 7
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II J. Wood '
The information provided will be used in updating the Reactor Vessel Integrity Database (RVID). 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
-j impact on LTOP 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) 415-1390.
Sincerely, I
Original signed by:
1 Allen G. Hansen, Project Manager Project Directorate lil-3 Division of Reactor Projects lil/IV Office of Nuclear Reactor Regulation Docket No. 50-346 j
Enclosure:
As Stated cc w/ encl: See next page l
l
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DISTRIBUTION Docket File PUBLIC l
PD3-3 R/F j
EAdensam (EGA1) l RSavio-OGC GGrant, Rill
. DOCUMENT NAME: G:\\DAVISBES\\DBA0540.RAI OFFICE PD3-3:PM q E
PD3-3:LA C
NAME AHansenMT EBamhill E/P DATE y/9 /98 '"
4/9 /98 OFFICIAL RECORD COPY i.I J
l...
l-J. Wood The information provided will be used in updating the Reactor Vessel Integrity Database (RVID).- Also, please note that RPV integrity analyses utilizing newly identified data could result l
in the i.eed 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 potemi impact on LTOP 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) 415-1390.
Sincerely,
[7' Allen G. Hansen, Project Manager 1%cj9ct Directorate ill-3 Division of Reactor Projects lil/IV Office of Nuclear Reactor Regulation Docket No. 50-346
Enclosure:
As Stated cc w/ encl: See next page l
1 John K. Wood Davis-Besse Nuclear Power Station, Unit 1 Toledo Edison Company cc:
Mary E. O'Reilly Robert E. Owen, Chief FirstEnergy Bureau of Radiological Health Davis-Besse Nuclear Power Station Service 5501 North State - Route 2 Ohio Department of Health Oak Harbor, OH 43449-9760 P.O. Box 118 Columbus, OH 43266-0118 James L. Freels Manager - Regulatory Affairs Toledo Edison Company James R. Williams, Chief of Staff Davis-Besse Nuclear Power Station Ohio Emergency Management Agency 5501 North State - Rouie 2 2855 West Dublin Granville Road Oak Harbor, OH 43449-9760 Columbus, OH 43235-2206 Gerald Chamoff, Esq.
Donna Owens, Director Shaw, Pittman, Potts Ohio Department of Commerce and Trowbridge Division of Industrial Compliance
' 2300 N Street, NW.
Bureau of Operations & Maintenance Washington, DC 20037 6606 Tussing Road P.O. Box 4009 Regional Administrator Reynoldsburg, OH 43068-9009 U.S. Nuclear Regulatory Commission 801 Warrenville Road Ohio Environmental Protection /gency Lisle, IL 60523-4351 DERR-Compliance Unit l
ATTN: Zack A. Clayton Robert B. Borsum P.O. Box 1049 Babcock & Wilcox Columbus, OH 43266-0149 l
Nuclear Power Generation Division 1700 Rockville Pike, Suite 525 State of Ohio l
Rockville, MD 20852 Public Utilities Commission 180 East Broad Street Resident inspector Columbus, OH 43266-0573 U.S. Nuclear Regulatory Commission 5503 North State Route 2 Attomey General Oak Harbor, OH 43449 Department of Attomey l
30 East Broad Street l
James H. Lash, Plant Manager Columbus, OH 43216 l
Toledo Edison Company Davis-Besse Nuclear Power Station President, Board of County 5501 North State Route 2 Commissioner of Ottawa County Oak Harbor, OH 43449-9760 Port Clinton, OH 43252
REQUEST FOR ADDITIONAL INFORMATION REACTOR PRESSURE VESSEL INTEGRITY l
Sechon 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. These I
data were provided by Framatome Technologies, Inc. (FTI) 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 these data was provided to members of the B&W Owners 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, l
Revision 1, Supplement 1, the NRC requests the following:
1 1.
An evaluation of the information in the references above and an assessment of its applicability to the determination of the best-estimate chemistry for all of your reactor pressure vessel (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 enalysis method chosen for determining the best-estimate. If the limiting material br your vessel's PTS /PT limits evaluation is not a weld, include the information requestec in Table 1 for the limiting material also. Furthermore, you should consider the information provided in Section 2.0 below on the use of l
surveillance data when responding.
l l
l 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 was 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 i
ENCLOSURE
2
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r 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 GQD9En 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 l-should then be provided for which assumption was chosen when the best-estimate chemistry -
l.
was determined.
1 Sechon 2.0. Evaluation and Use of Surveillance Data The chemical composition reports referenced in Section 1.0 include updated chemistry l
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 permits the determination of the best estimate chemical composition for the L
various sources of data including surveillance welds. Since the evaluation of surveillance data relies 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 'ntegrity (including low temperature overpressure (LTOP) setpoints and pressure-J temperature (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 l
surveillance data be provided for each heat of material for which surveillance weld data are available add a revision in the RPV integrity analyses (i.e., current licensing basis) is i
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 pressurized thermal shock (PTS)/PT limits evaluation is not a wold, 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 shou?d be considered in evaluating its integrity regardless of source per 10 CFR 50.61 (" Surveillance program results l
means any data that demonstrates the embrittlement trends for the limiting beltline material,
)
l 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.
}
3
-.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 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 differs 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 surveiliance weld is not determined in accordance with Reference 1 (that is, 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 b6 tween 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 (for example, operating temperature and surveillance data) to verify that the RTa for each vessel bdt3ne material is a bounding value. Regulatory Guide 1.99, Revision 2, describes two methods tw determining the amount of margin and the chemistry factor used in determining RT,. Posstion 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 indicates that the surveillance data set is not credible and the mesured values of ART, are less than the projected mean from the Tables plus the generie 20, the chemistry factor 3
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 infonnation 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 ARTa 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 Februsry 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
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4 RG1.99, 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 nickel content of the surveillance weld differs from the vessel weld, that is, 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 q
l 3.
If the limiting material for your plant changes or if the adjusted reference temperature for j
the limiting material increases as a result of the above evaluations, provide the revised RTprs value for the limiting material in accordance with 10 CFR 50.61. In addition, if the adjusted rte 7 value increased, provide a schedule for revising the PT and LTOP limits.
The schedule should ensure that cornpliance with 10 CFR 50 Appendix G is maintained.
Reference 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 and 3
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4' Table 2: Heat urvu Capsule ID Cu Ni irradiation Fluence Measured Date Used in 8
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Table 3: Heat xxxx Capsule ID Cu Ni irradiation Fluence Measured Acjusted Predicted (Adjusted a (including Temperature Factor
- ARTuo, A9Te, ART,c, Predicted) ARTuo, source)
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