ML17313A314
| ML17313A314 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 03/30/1998 |
| From: | Thomas K NRC (Affiliation Not Assigned) |
| To: | James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| References | |
| GL-92-01, GL-92-1, TAC-MA0561, TAC-MA0562, TAC-MA0563, TAC-MA561, TAC-MA562, TAC-MA563, NUDOCS 9804030357 | |
| Download: ML17313A314 (18) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 205554001 March 30, 1998 Mr. James M. Levine Senior Vice President, Nuclear Arizona Public Service Company Post Office Box 53S9S Phoenix, Arizona 85072-3999
SUBJECT:
REQUEST FOR ADDITIONALINFORMATIONREGARDING REACTOR PRESSURE VESSEL INTEGRITYAT PALO VERDE NUCLEAR GENERATING STATION (TAC NOS. MA0561, MA0562 AND MA0563)
Dear Mr. Levine:
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 integnty 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 d r I t'10CFR 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 dated September 11, 1996 for the Palo Verde Nuclear Generating Station.
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 (GEOG) 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.
In consideration of the data presented in the June 1997 CEOG report, the +RC requests that you confirm that your original response is still correct. The comments in the enclosed request for additional information (RAI) should be considered in the assessment ofyour original submittal
~ Ifthe report does include data that would alter 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 request for additional information within SO days of receipt of this letter. Ifa 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.
The information provided willbe 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 Perl 50.60, 10
'g CFR 50.61 (pressurized thermal shock, PTS), and Appendices G and H to 10 CFR Part 50, and ir304030357 930330 gl'(gQ) (QCQ (QP$
1
Mr. James M. Levine March 30, 1998 o address any potential impact on low temperature overpressure (LTOP) limits or pressure-temperature (PT) limits. Ifadditional license am'endments or assessments are necessary, the enclosure requests that you provide a schedule for such submittals.
Ifyou should have any questions regarding this request, please contact me at (301) 415-1362.
Sincerely, i,
),
4 Original Signed By Kristine M. Thomas, Project Manager Project Directorate IV-2
'Division of Reactor Project III/IV Office of Nuclear Reactor Regulation Docket Nos. STN 50-528, STN 50-'529.
and STN 50-530
Enclosure:
Request for Additional Information ccw/encl:
See next page DOCUMENT NAME: PVA0561.RAI
<<Docket File 3 PUBLIC PDIV-2 Reading EAdensam WBateman KThomas JClifford EPeyton OGC ACRS KPerkins, RIV WCFO PGwynn, RIV AHiser, EMCB GVissing OFC PDIV-2/PM P DIV-2/LA NAME KThomas 3 ~98 3/qg/98 DATE OFFICIAL RECORD COPY
I I
Mr. James M. Levine March 30, 1998 cc w/encl:
Mr. Steve Olea Arizona Corporation Commission 1200 W. Washington Street Phoenix, Arizona 85007 Mr. David Summers Public Service Company of New Mexico 414 Silver SW, ¹1206 Albuquerque, New Mexico 87102 Douglas Kent Porter Senior Counsel Southern California Edison Company Law Department, Generation Resources P.O. Box 800
- Rosemead, California 91770 Senior Resident Inspector USNRC P. O. Box 40 Buckeye, Arizona 85326 Regional Administrator, Region IV U. S. Nuclear Regulatory Commission Harris Tower 8 Pavillion 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 Chairman, Board of Supervisors
" ATTN: Chairman
. 301 W. Jefferson, 10th Floor Phoenix, Arizona 85003 Mr. Robert D. Bledsoe Southern California Edison Company 14300 Mesa Road, Drop D41-SONGS San Clemente, California 92672 Mr. Robert Henry Salt River'Project 6504 East Thomas Road Scottsdale, Arizona 85251 Terry Bassham, Esq.
General Counsel EI Paso Electric Company 123 W. Mills EI Paso, Texas 79901 Mr. Robert Burt Los Angeles Department of Water 8 Power Southern California Public Power Authority 111 North Hope Street, Room 1255-B Los Angeles, California 90051 Mr. Aubrey V. Godwin, Director Arizona Radiation Regulatory Agency 4814 South 40 Street Phoenix, Arizona 85040 Ms. Angela K. Krainik, Manager Nuclear Licensing Arizona Public Service Company P.O. Box 52034 Phoenix, Arizona 85072-2034 Mr. John C. Horne, Vice President Power Supply Palo Verde Services 2025 N. Third Street, Suite 220 Phoenix, Arizona 85004
I\\
RE VEST FOR ADDITIONALINFORMATION REACTO PRESSURE VESSEL INTEGRITY RIZONA PUBLIC SERVICE COMPANY PALO VERDE NUCLEAR GENERATING STATION UNITNOS.
1 2 AND 3 DOCKET NOS STN 50-528 STN 50-529 AND STN 50-530 Section 1.0- Assessment of B st-E timate Chemist 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 information was provided to the NRC by the Combustion Engineering Owners'roup 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:
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 fillout 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.
Ifthe 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, NEI, 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 NEI 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.
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 consumabfes, 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.
Ifinformation 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". Ajustification 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 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:
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.
Ifthe 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 (ifsurveillance 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.
Allsurveillance 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."). Ifany 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 credibilityof 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. Ifthe method for adjusting and/or normalizing the surveillance data when assessing credibility differfrom the methods documented in Reference 1, provide the technical basis for the adjustment and/or the normalization procedure.
Ifthe 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 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 RT>>~ 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 RT>>y. Position 1.1 describes the use of the Generic Tables in the Regulatory Guide. Position 2.1 describes the use of credible surveillance data.
Ifthe 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.
Ifthe evaluation of the surveillance data indicate that the surveillance data set is not credible and the measured values ofART>>y are less than the projected mean from the Tables plus the generic 2o~, 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 hRT>>, 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.
Ifthe 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 ZLRTgDyto 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, 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.
Ifthe limiting material for your plant changes or ifthe adjusted reference temperature for the limiting material increases as a result of the above evaluations, provide the revised RT~~ value for the limiting material in accordance with 10 CFR 50.61.
In addition, ifthe adjusted RTpy 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 Memorandum from Keith R. Wichman to Edmund J. Sullivan, "Meeting Summary for November 12, 1997 Meeting with Owners Group Representatives and NEI Regarding Review of Responses to Generic Letter 92-01, Revision 1, Supplement 1 Responses",
dated November 19, 1997.
Attachments:
- 1. Table 1
- 2. Table 2 and Table 3
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TABLE 1 Facility:
Vessel Manufacturer:
Information requested on RPV Weld and/or Limiting Materials RPV Weld Wire Heat"'est-Estimate Copper Best-Estimate Nickel EOL ID Fluence (x 10")
Assigned Material Chemistry Factor (CF)
Method of Determining CF(2)
Initial RT(),
(RTNoT)
o, Margin ART or RT~,
at EOL (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 f t e n
i eth and D t Used for Each Weld Wire Hea Weld Wir H a
~Di ssion Attachment 1
0 1 ~
Table 2: Heat xxxx Capsule ID (induding source)
Cu Ni Irradiation Temperature
('F)
Fluence (x10"n/cm')
Measured hRTggr
('F)
Data Used in Assessing Vessel (Yor N)
Table 3: Heat xxxx Capsule ID (including source)
Cu Irradiation Temperature
('F)
Fluence Factor Measured BRT~)r
('F)
Adjusted BRT~r
('F)
Predicted hRTmr
('F)
(Adjusted-Predicted) hRT~,
('F)
4 4
'I 1