ML20236F551

Forwards RAI Re GL 92-01,rev 1,suppl,1, Reactor Vessel Structural Integrity, Issued in May 1995

ML20236F551
Person / Time
Site:	Monticello
Issue date:	06/29/1998
From:	Kim T NRC (Affiliation Not Assigned)
To:	Richard Anderson NORTHERN STATES POWER CO.
References
GL-92-01, GL-92-1, TAC-MA1199, NUDOCS 9807020206
Download: ML20236F551 (7)

Text

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p- UNITED STATES j

NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20666 4001

.....l June 29, 1998 Mr. Roger O. Anderson, Director Nuclear Energy Engineering Northem States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401

SUBJECT:

MONTICELLO NUCLEAR GENERATING Pl. ANT- REQUEST FOR ADDITIONAL INFORMATION REGARDING REACTOR PRESSURE VESSEL INTEGRITY TAC NO. MA1199) .

Dear Mr. Anderson:

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 generic letter 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 l 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 C?R 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 (P-T) limits.

After reviewing your response, the NRC issued you a letter dated December 9,1996. In this  !

letter we acknowledged receipt of your response, noted that additional RPV information may become available as a result of Owners Group efforts, and requested that you provide us with the results of the Owners Groups' programs relative to your plant. We further indicated that a plant-specific TAC Number may be opened to review this material. Following issuance of these letters, the BWR [ Boiling-Water Reactor] Vessel and Intemals Project (BWRVIP) submitted the /

/

report " Update of Bounding Assessment of BWR/2-6 Reactor Pressure Vessel integrity issues (BWRVIP-46)." This report included bounding assessments of new data from (1) the Combustion Engineering Owners Group (CEOG) database released in July 1997 which contains all known data for CE-fabricated welds in pressurized-water reactor and BWR vessels; /

(2) Framatome Technologies incorporated (FTI) analyses of Linde 80 welds which are documented in NRC Inspection Report 99901300/97-01 dated January 28,1998; (3) FTI's analysis of electro-slag welds which was referenced in a Dresden and Quad Cities P-T limits submittal dated September 20,1996; and (4) Chicago Bridge and Iron quality assurance records. New data for one vessel fabricated by Hitachi was also included in the BWRVIP l report.

! l The staff is requesting that you re-evaluate the RPV weld chemistry values that you have previously submitted as part of your licensing basis in light of the information presented in the CEOG, FTl and BWRVIP reports. The staff expects that you will assess this new w;

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June'29, 1998 i

information to determine whether any values of RPV weld c$mistry need to be revised for your

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Lfacility. Therefore, in order to provide a complete response to items 2,3 and 4 of the generic letter, the NRC requests that you provide a' response to the enclosed request for additional information (RAl) within 90 days of receipt of this letter, 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.

i, ' 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 50.60, and

~ Appendices G and H to 10 CFR Part 50, and to address any potential impact on P-T limits. If

• additional license amendments or assessments are necessary, we request that you provide a schedule for such submittals as stated in the enclosure.

if you should have any questions regarding this request, please contact me at 301-415-1392.

Sincerely.

Original si8ned by:

Tae Kim, Senior Project Manager Project Directorate lil-1 Division of Reactor Projects - lil/IV-Office of Nuclear Reactor Regulation Docket No. 50-263

Enclosure:

As stated cc w/ encl: See next page DISTRIBUTION:

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R. O. Anderson informatiori to determine whether any values of RPV weld chemistry need to be revised for your facility. Therefore, in order to provide a complete response to items 2,3 and 4 of the generic letter, the NRC requests that you provide a response to the enclosed request for additional information (RAl) within 90 days of receipt of this letter. If a question does not apply to your situation, please indicate this in your RA! 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 50.60, and Appendices G and H to 10 CFR Part 50, and to address any potential impact on P-T limits, if additional license amendments or assessments are necessary, we request that you provide a schedule for such submittals as stated in the enclosure.

If you should have any questions regarding this request, please contact me at 301-415-1392.

Sincerely, 4c Tae Kim, Senior Project Manager i Project Directorate ill-1 Division of Reactor Projects -lil/IV Office of Nuclear Reactor Regulation Docket No. 50-263

Enclosure:

As stated cc w/ encl: See next pege l

l 4

l Mr. Roger O. Anderson, Director Monticello Nuclear Generating Plant Northern States Power Company

.cc:

J. E. Silberg, Esquire Kris Sanda, Commissioner Shaw, Pittman. Potts and Trowbridge Department of Public Service 2300 N Street, N. W. 121 Seventh Place East Washington DC 20037 Suite 200 St. Paul, Minnesota 55101-2145 U.S. Nuclear Regulatory Commission Resident inspector's Office Adonis A. Nebiett 2807.W. County Road 75 Assistant Attomey General )

Monticello, Minnesota 55362 Office of the Attomey General 445 Minnesota Street Plant Manager Suite 900 Monticello Nuclear Generating Plant St. Paul, Minnesota 55101-2127 ATTN: Site Licensing j

Northem States Power Company 2807 West County Road 75 Monticello, Minnesota 55362-9637 Robert Nelson, President Minnesota Environmental Control Citizens Association (MECCA) 1051 South McKnight Road St. Paul, Minnesota 55119 Commissioner Minnesota Pollution Control Agency 520 Lafayette Road St. Paul, Minnesota 55119 Regional Administrator, Region l!!

U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, Illinois 60532-4351 Commissioner of Health Minnesota Department of Health -

717 Delaware Street, S. E.

Minneapolis, Minnesota 55440 Darla Groshens, Auditor / Treasurer ,

l Wright County Govemment Center 10 NW Second Street Buffalo, Minnesota 55313 January 1995 l

l l

i l

4 I

l REQUEST FOR ADDITIONAL INFORMATION l REACTOR PRESSURE VESSEL INTEGRITY l

Section 1.0: Assessment of Best-Estimate Chemistry  ;

The staff recently received the Boiling-Water Reactor Vessel and Intemals Project (BWRVIP)  ;

. report " Update of Bounding Assessment of BWR/2-6 Reactor Pressure Vessel Integrity issues (BWRVIP-46)."

Based on this information, in accordance with the provisions of Generic Letter 92-01, Revision 1, Supplement 1, the NRC requests the following:

l 1. An evaluation of the bounding assessment in the reference above and 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. If the limiting material for your vessel's pressure-temperature (P-T) limits evaluation is not a weld, include the information requested in Table 1 for the limiting material also.

t 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" (Ref.1). The information in Reference 1 may be useful in helping you to prepare your response.

t l In addition to the issues discussed in the referenced meeting, you should also consider what

i. 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 determined to

! be the appropriate method for determining the best-estimate chemistry. If a weld (or welds)

L 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 L tandem arc welds) of weld consumables, it may be appropriate to consider all chemistry L samples from that weld (or welds) as samples from "one weld" for the purposes of l best-estimate chemistry determination. If information is not available to confirm the j 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.

1 ENCLOSURE l

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Section 2.0: P-T Limit Evaluation

2. If the lim; ting material for your plant changes or if the 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 addition, if the adjusted RT, value increased, i provide a schedule for revising the P-T limits. The schedule should ensure that compliance with 10 CFR Part 50 Appendix G is maintained. l Reference

1. Memorandum dated November 19,1997, 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."

Attachment:

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