ML20216C112
| ML20216C112 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/08/1998 |
| From: | Clifford J NRC (Affiliation Not Assigned) |
| To: | Ray H SOUTHERN CALIFORNIA EDISON CO. |
| References | |
| GL-92-01, GL-92-1, TAC-MA0569, TAC-MA0570, TAC-MA569, TAC-MA570, NUDOCS 9804140320 | |
| Download: ML20216C112 (9) | |
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UNITED !!TATES S
NUCLEAR REGULATORY COMMISSION
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WAsHINGTO%, D.C. 2066Mmoi April 8,1998 Mr. Harold B. Ray Executive Vice President Southem Califomia Edison Company San Onofre Nuclear Generating Station P. O. Box 128 San Clemente, Califomia 92674-0128
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION REGARDING REACTOR PRESSURE VESSEL INTEGRITY AT SAN ONOFRE NUCLEAR GENEP.ATING STATION UNITS 2 AND 3 (TAC NOS. MA0569 AND MA0570)
Dear Mr. Ray:
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 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 (USE) evaluations), and any potential impact on f
low temperature overpressure (LTOP) limits or pressure-temperature (PT) limits.
After reviewing your response, the NRC issued you a letter dated August 5,1996. 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
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additional information regarding the structural integrity of your RPV was available at that time.
t In July 1997, the Combustion Engineering Owners Group (CEOG) provided a report with I
additional RPV weld chemistry data for RPVs fabncated by CE. This additional RPV weld l
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 NRC requests that you confirm that your original response is still correct. The comments in the
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enclosed request for additional information (RAI) should be considered in the assessment of your original submittal. If the report does include data that would alter your original evaluation
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and in order to provide a complete response to items 2,3 and 4 of the GL, the NRC requests j
that you provide a response to the enclosed request for additional information within 90 days of receipt of this letter. If a question does not apply to your situation, please indicats this in your (j)
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 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 (pressurized thermal shock, PTS), and Appendices G and H to 10 CFR Part 50, and 9804140320 980408
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PDR ADOCK 05000361
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. Mr. Harold B. Ray
-2 April 8, 1998 l
to address any potential impact on low temperature overprr,ssure (LTOP) limits or pressure-4 temperature (PT) limits. If additionallicense amendments or assessments are necessary, the
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enclosure requests that you provide a schedule for such submittals.
If you should have any questions regarding this request, please contact me at (310) 415-1352.
Sincerely, Original Signed By James W. Clifford, Senior Project Manager Project Directorate IV-2 Division of Reactor Projects ill/IV Office of Nuclear Reactor Regulation Docket Nos. 50-361 DISTRIBUTION:
and 50-362
' Docket PUBLIC
Enclosure:
Request for AdditionalInformation PDIV-2 Reading EAdensam cc w/ encl: See next page WBateman JClifford DLoveless EPeyton OGC ACRS KPerkins, RIV WCFO PGwynn, RIV AHiser, EMCB GVissing Document Name: vessel. son
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OFC PDIV-M/
PDIV-2 PDIV-2 l,
NAME DLove EPey2t JCliffob DATE 4 /b /98 4 / S /98 4 / [/98 OFFICIAL RECORD COPY l
l
s Mr. Harold B. Ray - April 8, 1998 J
cc w/ encl:
Mr. R. W. Krieger, Vice President Resident inspector / San Onofre NPS Southem Califomia Edison C ampany c/o U.S. Nuclear Regulatory Commission San Onofre Nuclear Generating Station Post Office Box 4329 P. O. Box 128 San Clemente, California 92674 San Clemente, California-92674-0128 Chairman, Board of Supervisors City of San Clemente County of San Diego 100 Avenida Presidio 1600 Pacific Highway, Room 335 San Clemente, Califomia 92672 San Diego, Califomia 92101 Mr. Dwight E. Nunn, Vice President Alan R. Watts, Esq.
Southem Califomia Edison Company Woodruff, Spradlin & Smart San Onofre Nuclear Generating Station 701 S. Parker St. No. 7000 P.O. Box 128 Orange, Califomia 92668-4702 San Clemente, Califomia 92674-0128 Mr. Sherwin Harris Resource Project Manager Public Utilities Department City of Riverside 3900 Main Street Riverside, Califomia 92522 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Harris Tower & Pavilion 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 Mr. Terry Winter Manager, Power Operations San Diego Gas & Electric Company P.O. Box 1831 San Diego, California 92112-4150
. Mr. Steve Hsu Radiologic Health Branch State Department of Health Services
~ Post Office Box 942732 l
Sacramento, California 94234 i
l I
REQUEST FOR ADDITIONAL INFORMATION REACTOR PRESSURE VESSEL INTEGRITY SOUTHERN CALIFORNIA EDISON COMPANY SAN ONOFRE NUCLEAR GENERATING STATION. UNIT NOS. 2 AND 3 DOCKET NOS. 50-361 AND 50-362 1
Section 1.0 - Assessment of Best-Estimate Chemistrv l
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 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-esumate 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 i
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, 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.
j 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 l
consideration when a mean-of-the-means or coil-weighted average approach is determineri 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
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eht fo yna fI.)".H xidneppA,05 RFC 01 rep detargetni margorp ecnallievrus tuohtiw ro htiw stnalp rehto ta smargorp ecnallievrus morf ro srotcaer tset morf atad ot detimil ton tub gnidulcni
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.stnemmoc dna snoitseuq gniwollof eht htiw gnola esnopser siht ni deredisnoc eb dluohs stroper yrtsimehc eht gnidrager IAR siht fo 01 noitceS ni dessucsid noitamrofni ehT
.)lairetam siht rof elbaliava era atad ecnallievrus fi( lairetam gmtimil eht rof selbat eht ni detseuqer noitamrofni eht edulcni,dlew a ton si noitaulave stimil TP/STP s'lessev ruoy rof lairetam gnitimil eht fI.desserdda lairetam fo taeh hcae rof desu eb dluohs selbat etarapeS
.dilav niamer snoitaulave dettimbus ylsuoiverp taht noitacifitrec a )2( ro dedeen si)sisab gnisnecil tnerruc,.e.i( sesylana ytirgetni VPR eht ni noisiver a dna elbaliava era atad dlew ecnallievrus hcihw rof lairetam fo taeh hcae rof dedivorp eb atad ecnallievrus eht morf rotcaf yrtsimehc eht dna,3 elbaT,2 elbaT ni detsil noitamrofni eht )1( taht 2
- gniwollof eht stseuqer CRN eht,1 tnemelppuS,1 l
noisiveR,10-29 retteL cireneG fo snoisivorp eht htiw tnetsisnoc dna noitamrofni siht no desaB 05 trap RFC 01 ot H dna G secidneppA dna,16 05 RFC 01
,06 05 RFC 01 fo stnemeriuqer eht rep )stimil TP dna stnioptes POTL gnidulcni( ytirgetni VPR fo snoitaulave suoiverp esiver ot deen eht ni tluser yam stroper eseht ni noitamrofni eht
,dlew ecnallievrus eht dna dlew VPR eht fo noitisopmoc lacimehc etamitse tseb eht htob no yler atad ecnallievrus fo noitaulave eht ecniS.sdlew ecnallievrus gnidulcni atad fc secruos suoirav eht rof noitisopmoc lacimehc etamitse tseb eht fo noitanimreted eht stimrep sihT.lairetam fo taeh eht fo noitisopmoc lacimehc eht gnitamitse ni desu atad ecruos eht edulcni osla tub eulav etamitse tseb detseggus a edivorp ylno ton stroper esehT.latem dlew fo staeh rof setamitse yrtsimehc detadpu sedulcni 01 noitceS ni decnerefer troper noitisopmoc lacimehc ehT ataD ecnallievruS fo esU dna noitaulavE - 0 2 noitceS
.denimreted saw yrtsimehc etamitse-tseb eht nehw nesohc saw noitpmussa hcihw rof dedivorp eb neht dluohs noitacifitsuj A. sdlew elpitlum"fo rebmun etairporppa na morf emac atad eht taht gnimussa yb dna "dlew eno morf emac atad eht gnimussa yb htob detaulave eb dluohs yrtsimehc etamitse
-tseb eht,emas"eht era sliated eht emussa ylbanosaer ot stsixe ecnedive tneiciffus tub,sliated denoitnemerofa eht mrifnoc ot elbaliava ton si noitamrofni fI.noitanimreted yrtsimehc etamitse
-tseb fo sesoprup eht rof "dlew eno" morf selpmas sa )sdlew ro( dlew taht morf selpmas I
yrtsimehc lla redisnoc ot etairporppa eb yam ti,selbamusnoc dlew fo )sdlew cra mednat j
fo esac eht ni slioc ro( lioc emas eht gnisu dna,sretemarap tupni gnidlew ralimis gnisu, naps.
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of and using the same coil (or coils in the case it may be appropriate to consider all chemistry span, using similar welding input parameters, l
les from *one weld" for the purposes of best-f mentioned l
tandem arc welds) of weld consumables, tion is not available to confirm the a o best-samples from that weld (or welds) as samp eld" and estimate chemistry determination, if informadetails, b d both by assuming the data came from "one w Ajustification ppropriate number of " multiple welds".
t chemistry estimate chemistry should be evaluate tion was chosen when the best-estima e by assuming that the data came from an a shouid then be provided for which assump was determined.
Data SRG1LQ12A_- Ev.ahtattaa.and.ilic.oLStatveillinicad in Section 1 t estimate reports not only provide a suggested f the heat The chemical composition report reference osition for the estimates for heats of weld metal. These ti n of the best estimate chemical comp illance data value but also include the source data use illance welds. Since the evaluation of surv illance weld, of material. This permits the determina o l omposition of the RPV weld and the surve s of RPV various sources of data including surve sult in the need to revise previous ev 60, rely on both the best estimate chemica c the information in these reports may re integrity (including LTOP setpoints and PT m10 CFR Part 50.
i ion 10 CFR 50.61, and Appendices G and H to h the provisions of Ge l
Based on this information and consistent wit 1, S f ll wireg:
the l
l 2 Table 3, and the chemistry factor from d data t f material for which surveillance w l
i )is
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that (1) the information listed in Tab e, surveillance V integrity analyses (i.e., current licensing
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l submitted evaluations remain valid.
2.
are available and a revisionin the RP l
h atof materialaddressed. If the needed or (2) a certification that previous y ti n
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Separate tables should be used for each emat f this l
l requested in the tables for the limitmg m
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ld be f this RAI regarding the chemistry reports s material).
f llowing questions and comments.
The information discussed in Section 1.0 ocons m results e per 10 CFR 50E1 (" Surveillance progra
- ial, All surveillance program results for the heats o ittlement trends for the limiting beltline ma th r plants evaluating its integrity regardless of sourc ctors or from surveillance programs at o e means any data that demonstrates the embrinc f
y of the
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ated per 10 CFR 50, Appendix H."). I an d for a h calculation of the embrittlement ided.
with or without surveillance program integr data provided in Table 2 are not used in t e f
particular RPV weld, the technical basis or
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. 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 '4ources 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 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 RTuoy for each vessel beltline material is a bounding value. Regulatory Guide 1.99, Revision 2 describes two i
methods for determining the amount of margin and the chemistry factor used in determining RTwo7 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 ARTuoy are less than the projected mean from the iables plus the generic 20, the chemistry factor 6
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).
l Based on the information provided in Table 2 along with the best estimate chemical l
composition of the heat of material and the irradiation temperature of the plant whose vesselis l
being assessed, the chemistry factor of the RPV weld can be determined. Note that the I
adjusted ARTuor for a particular surveillance data point may be one value when determining
. edibility 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.
1 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 i
4 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 ARTuor to
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account for differences in the chemical composition between the surveillance weld and the V
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 surve!ilance weld, the ratio procedure must be used.
4.ction 3.0 - PTS /PT Limit Evaluation 3.
If the limiting material for your plant changes or if the adjusted reference temperature for the 8imiting materialincreases as a result of the above evaluations, provide the revised RT,rs value for the limiting materialin accordance with 10 CFR 50.61. In addition, if the adjusted RTuor 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.
Referenca 7
1.
Memorandum from Keith R. Wichman to Edmund J. Suitivan, " Meeting Summary for November 12,1997 Meeting with Cwners 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. Table 2 and Tnble 3
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