ML20217F085
| ML20217F085 | |
| Person / Time | |
|---|---|
| Issue date: | 03/27/1998 |
| From: | Lainas G NRC (Affiliation Not Assigned) |
| To: | Hardies R BALTIMORE GAS & ELECTRIC CO. |
| References | |
| GL-92-01, GL-92-1, NUDOCS 9803310270 | |
| Download: ML20217F085 (8) | |
Text
__
p aeg k
UNITED STATES y* )
,j NUCLEAR REGULATORY COMMISSION g
e WASHINGTON, D.C. 20666-0(W
,o March 27, 1998 Mr. Robert O. Hardies Chairman, C-E Owners Group Reactor Vessel Working Group Baltimore Gas and Electric Company 1650 Calvert Cliffs Parkway Lusby, Maryland 20637
Subject:
COMBUSTION ENGINEERING OWNERS GROUP REPORT CE NPSD-1039 REVISION 2, *BEST ESTIMATE COPPER AND NICKEL VALUES IN CE FABRICATED REACTOR VESSEL WELDS" AND CE NPSD-1039 APPENDIX A, REVISION 2, *CE REACTOR VESSEL WELD PROPERTIES DATABASE VOLUMES 1 AND 2"
Dear Mr. Hardies:
On May 19,1995, the NRC issued Generic Letter 92-01, Revision 1, Supplement 1 (GL 92-01, Rev.1, Supp.1), " Reactor Vessel Structural Integrity." In GL 92-01, Rev.1, Supp.1, the NRC requested that nuclear licensees " identify, collect, and report any new data pertinent to [the) analysis of [the) structural integrity of their reactor pressure vessels (RPVs)."
The Supplement also requested that licensees assess the impact of any new data relative to requirements 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 (P-T) limits.
In response to GL 02 01, Rev.1, Supp.1, licensees who possess RPVs which were fabricated by Combustion Engineering (CE) indicated that they would participate in ongoing efforts by the Combustion Engineering Owners Group Reactor Vessel Working Group (CEOG RVWG) to collect and assess all relevant chemistry data. Via letters dated April 21 and July 14,1997, the CEOG RVWG submitted the CE NPSD-1039, Revision 2 reports (for information only) which addressed Ell relevant chemistry data for CE fabricated vessels. While the staff did not formally review these reports, the staff did examine some of the data and analysis methodologies used therein. This was done since it is the staff's expectation that licensees with CE RPVs will be reviewing this information as part of their final close out of GL 92-01, Supp.1 activities and in order to respond to forthcoming plant-specific requests for additional information (RAls) on GL 92-01 chemistry and surveillance data issues. These issues and the RAls were also discussed at a NRC/NEl meeting on November 12,1997, and at the NRC/NEl Reactor Pressure Vessel Integrity Workshop on February 12-13,1998.
This letter is being issued to provide comments (see Enclosure) regarding the information presented in the subject reports. The staff anticipates that, based on the questions in the RAls, licensees may request assistance from the CEOG RVWG in prepa+ig their responses and these comments may further clarify issues in the staff's RAl. It should be noted that all of these comments are intended to be fully consistent with the information that the staff presented at the 388 18E8 H??l R0+z M
f3 Q 9t j7/&
/
C PDR O 1j Q itc h Q Qf wn.
w 98 - fs
Robert O. Hardies November 12,1997, and February 12-13,1998, meetings, and with any information presented in -
the plant-specific RAls. If you have any questions regarding this letter or the plant-specific RAls, please contact Keith R. Wichman of my staff at (301) 415-2757 or by e-mail at KRW@nrc. gov.
Also, I want to take this opportunity to acknowledge the efforts of the CEOG. The generic work sponsored by the CEOG was substantial and represents a significant contribution toward the effective management of RPV issues.
Thank you for your cooperation.
Sincerely,
.0L (p r Gus C. ainas, Acting Director Division of Engineering Office of Nuclear Reactor Regulation
Enclosure:
As stated cc: See next page DISTRIBUTION EMCB R/F MMayfield Atee JSt 1 snider AHiser File Center Pbi PUBLIC e
DOCUMENT NAME: G:\\MITCHELL\\CEOGCLSE.LTR IMOICATE IN BOX: *C"= COPY W/O ATTACHMENT / ENCLOSURE. "E*= COPY WIATT/ ENCL, *N"=NO COPY sEE enEvious CONCu mANCE l OFFICE EMCB:DE EMCB:DE EMCB:DE (A) BC:EMCB:DE NAME MMitchell*
BElliot*
KWichman*
EJSutlivan* -
DATE 02/19/98 02/19/98,p.,02/23/98 03 /04 /98 OFFICE (A) BC:PGEB (A) DD.DE(
(A) D:DEFr l
NAME TEssig*
JStrosnidd GlainasW N
DATE.
03/23/96 6 /2b/98 3 / /98 OFFICIAL RECORD COPY
' Robert O. Hard'Is questions regarding this letter or the plant-specific RAls, please contact Matthew A. Mitchel! of my staff at (301) 415-3303 or by e-mail at MAM4 @ nrc. gov.
Thank you for your cooperation.
Sincerely, Gus C. Lainas, Acting Director Division of Engineering Office of Nuclear Reactor Regulation
Enclosure:
As stated cc: See next page i
l DISTRIBUTION:
EMCB R/F MMayfield Alee JStrosnider AHiser File Center PWen PUBLIC DOCUMENT NAME: G:\\MITCHELL\\CEOGCLSE.LTR INDICATE IN BOX: "C"= COPY W/O ATTACHMENTENCLOSURE,"E"= COPY W/ATTENCL,"N"sNO COPY
- SEE PREVIOUS CONCURRANCE l
OFHCE EMCB:DE EMCB:DE EMCB:DE (A) BC:EMCB:DE NAME MMitchell*
BElliot*
KWichman*
EJSullivan*
DATE 02/19/98 02/19/98 02/23/98 03 /04 98 m-m mm muuuuuuuuum OFFICE BC:PGEB (A) DD:DE (A) D:DE NAME TEssig JStrosnider Glainas DATE 3 / 23/98
/ /98
/ /98 OFFICIAL RECORD COPY 3 y3 L-----
i
- Robert O Hardi:s
- questions regarding this letter or the plant-specific RAls, please contact Matthew A. Mitchell of my staff at (301) 415-3303 or by e-mail at MAM4 @nrc. gov.
Thank you for your cooperation.
Sincerely, 1
Gus C. Lainas, Acting Director f
Division of Engineering l
0" ice of Nuclear Reactor Regulation
Enclosure:
As Stated CC: Sc.4 blevt P9 DISTRIBUTION:
EMCB R/F MMayfield Alee JStrosnider AHiser File Center PWen S'.'.;giudei Pustic DOCUMENT NAME: G:\\MITCHELL\\CEOGCLSE.LTR INDICATE IN SOX:"C" SCOPY W/O ATTACHMENTENCLOSURE,"E"= COPY WIATTENCL,"N"mNO COPY
- SEE PREVIOUS CONCURRANCE OFFICE EMCB:DE E
EMCB:DE 6
EMCB:DE 6
(A) BC:EMCB:DE C
NAME MMitchell*
BElliot' KWichman*
EJSullivan N DATE 02/19/98 02/19/98 02/23/98
'$ /d /98
-.-.--mhm m-m OFFICE (A) BC:PGEB (A) DD:DE (A) D:DE NAME TEssig JStrosnider Glainas DATE
/ /98
/ /98
/ /98 OFFICIAL RECORD COPY
' Robert O. H:rdies
- i additional ghestions regarding this letter or the plant-specific RAls, please contact Matthew A.
Mitchellef'my staff at (301) 415-3303 or by e-mail at MAM4 @nrc. gov.
Thank you for your cooperation.
Sincerely, Edmund J. Sullivan, Acting Chief, Materials and Chemical Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation
Enclosure:
As Stated
- ga[)
(h 9
DISTRIBUTION:
EMCB R/F MMayfield Alee S
JStrosnider AHiser File Center pga DOCUMENT NAME: G:\\MITCHELL\\CEOGCLS2.LTR p
y INDICATE M BOM: "C"= COPY W/O ATTACHMENT / ENCLOSURE,"E"= COPY W/ATT/gNCL. "N"mNO COPY Orrect EMCB:DE E
EMCB:DE E
EMCB:
1 /
E (A) BbMCB:DE NAME MMitcheMM BElliot dY a
EJSullivan
@/ h/98 3b8
/ /98 l
DATE 8//f/")8 OFFICIAL RECORD COPY
CE OWNERS CROUP Project No. 692 cc: Mr. Gordon C. Bischoff CEOG Project Manager ABB Combustion Engineering MS 9615-1932 2000 Day Hill Road
)
Windsor, CT 06095 David Pilmer, Chairman CE Owners Group San Onofre Nuclear Generating Station 14300 Mesa Road San Clemente, CA 92672 Charles B. Brinkman, Director Nuclear Systems Licensing ABB-Combustion Engineering, Inc.
P. O. Box 500 2000 Day Hill Road Windsor, CT 06095 Charles B. Brinkman, Manager Washington Nuclear Operations ABB-Combustion Engineering, Inc.
12300 Twinbrook Parkway, Suite 330 Rockville, MD 20852
'ime r...,a e-
=-
--e.=
.a
,op.
STAFF COMMENTS REGARDING CEOG RVWG REPORT CE NPSD-1039. REVISION 2. "BEST ESTIMATE COPPER AND NICKEL VALUES IN CE FABRICATED REACTOR VESSEL WELDS" AND CE NPSD-1039 APPENDIA A. REVISION 2. "CE REACTOR VESSEL 1NELD PROPERTIES DATABASE VOLUMES 1 AND 2 Comment #1 in general, the methods proposed for determining best-estimate chemistries seemed to be reasonable.. When suficient data is available from several sources, the use of group-weighted means or coi!-weighted means in lieu of the simple mean approach seems to be appropriate.
However, if the analysis procedures result in significantly different values, the cause of this differencs should be carefully considered before a best-estimate methodology is chosen and a
' detailed justification should be provided in all plant-specific RAI responses to support the chosen Lanalysis methodology.
Comment #2 When a coil-weighted mean or group-weighted mean is to be determined, special attention should be paid to weld qualification data. Recently it has come to the staffs attention that the rationale for grouping or separation of weld qualification data is not as adequately explained as necessary in the report. A reexamination of this issue may be necessary and the staff explained at the February 12-13,1998, meetings, that the questions of when the weld qualification data was taken, what the welding input parameters were, if one or more coils of wire was used when preparing the sampies, etc. are valid concems when determining whether or not the data should be combined as one " weld" or treated at having come from multiple " welds." Other information not listed here may also need to be considered and cited in the responses to plant-specific RAls.
If this information cannot be determined with sufficient certainty, consider the effect on the analysis of the we'd wire heat best-estimate if the data is assumed to be from "one" or " multiple" welds.
Comment #3
~ The staff has determined that, to comply with the current requirements of 10 CFR 50.61, heat-specific values for copper and nickel can be assigned based on one or more valid data points.
- However, the staff recognizes that heat-specific values based on limited data may not appear to be consistent with the generic values for that class of material. In such cases, the staff may consider (for information only) the impact of the use of generic values in RPV integrity assessments and the adequacy of associated margin terms. Licensees should be aware of this based upon the information presented by the staff at the November 12,1997, and February 12-13,1998/ meetings, noted in the cover letter.
Comment #4
. If no valid data exists for determining either the copper or nickel content (or both) of a particular
- weld wire heat, the a generic value for that class of material plus one standard deviation should be used (to be consistent with Regulatory Guide 1.09, Rev. 2 and 10 CFR 50.61).
A' m
..,. ENCLOSURE NOTE! The ne' veral comments regard the screening of data points and shou;d be considered con intly whenever a best-estimate chemistry evaluation is performed. They have been subdruded into the comments below for ease of discussion.
Comment #5 The staff agrees that some data points which might be initially attributed to a specific weld wire heat may be excluded as more information regarding them is considered. A data point that represorts a duplicate record, that is not traceable to a specific weld wire heat, or that is clearly identified as having been from an atypical sample location (e.g., from the weld backgroove or HAZ regions) may be excluded from the analysis. However, the staff determined that
" consistency with known valid data" alone does not provide sufficient reason to exclude a data point prior to a rigorous analysis for statistical outliers. This is noted as a possibility in Section 2.2.4 of the report and is reflected in the flow chart of Figure 2-1. To do so may inappropriately
. Influence the outlier analysis.
Comment #6 When testing the remaining " presumably valid data" for statistical outliers, the staff has concems regarding the statistical significance of the use of Chauvenet's Criteria.. It has been suggested by the staff that other " outlier" identification methods, for example Grubbs' Test, would be more appropriate.
Comment #7 Finaily, when a statistical outlier is identified a physical justification should be provided to support why that data point may not be representative of the weld wire heat. The plant-specific RAls request that the data used for the best-estimate chemistry determination be identified and the issue of which data points were used and which ones were screened out of the final evaluation (and why) should be addressed therein.
u I [,.,
- ...,,,a-.%
- ,
- e-+.
.__