ML20151N195

Summarizes 880714 Meeting W/Util Re PTS Ref Temp (Rtpts). Concerns Could Be Resolved by Establishing Initial Rtpts Value for Matl,Per Paragraph NB-2331 of ASME Code

ML20151N195
Person / Time
Site:	Rancho Seco
Issue date:	08/04/1988
From:	Knighton G Office of Nuclear Reactor Regulation
To:	Firlit J SACRAMENTO MUNICIPAL UTILITY DISTRICT
References
NUDOCS 8808080137
Download: ML20151N195 (5)

Text

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%,,,,,# August 4, 1988 Docket No. 50-312 Mr. Joe Firlit Chief Executive Office, Nuclear Rancho Seco Nuclear Generating Station 14440 Twin Cities Road Herald, California 95638-9799

SUBJECT:

WF-70 PRESSURIZED THERMAL SH0CK REFERENCE TEMPERATURE A meeting was held at NRC Headquarters on July 14, 1988 (meeting minutes attached) with the NRC staff, the Sacramento Municipal Utility District (SMUD),

and Babcock and Wilcox (B&W) to discuss the pressurized thermal shock reference temperature (RTpts) for the Rancho Seco reactor. The meeting followed staff review of a letter dated June 16, 1988 in which SMUD responded to staff concerns regarding RTpts for WF-70 weld material. WF-70 weld material is used in the Rancho Seco reactor vessel and other reactor vessels manufactured by B&W.

At issue was the appropriate value of the initial RTpts for unirradiated WF-70 material. The Code of Federal Regulations, 10 CFR 50.61, specifies that if a measured initial reference temperature is not available then a generic mean value of 0 degrees F. must be used for the subject material and the margin to account for uncertainties is increased accordingly. The Rancho Seco Updated Safety Analysis Report assumes O degrees F. as the initial RTpts. The initial RTpts is used along with accumulated neutron fluence and the uncertainty margin to compute RTpts during the operating life of the reactor vessel.

Recent publications by Babcock and Wilcox (BAW-1975 and BAW-1920P) identify possible values for the initial RTpts of WF-70. Although the RTpts measure-ments conducted to date may not meet the ASME Code criteria for measuring inntial RTpts, the test results appear to indicate that the initial RTpts of unirradiated WF-70 may be considerably greater than 0 degrees F. Hence, it may not be conservative to use 0 degrees F. as the initial RTpts for WF-70.

Based on available data, it does not appear that the Rancho Seco reactor vessel has reached the screening criteria as defined by 10 CFR 50.61. However, the test results raise concerns that the screening criteria may be reached sometime A

M, 8808080137 PDR 880804 P ADOCK 05000312 PDC

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Letter to Mr. Firlit ...

during the projected operating life of the Rancho Seco reactor. These concerns could be resolved by establishing the initial RTpts value for the material in accordance with Paragraph flB-2331 of the ASME Code Section III. Within 60 days please advise Mr. George Kalman, our project manager for Rancho Seco, of your efforts to resolve these concerns.

Sincerely,

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' George X. Knighton, Director Project Directorate Y Division of Reactt.; Frojects - III, IV, V and SpeciaT Projects

Enclosure:

As stated cc: Jim Taylor, B&W See next page J

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. Letter to Mr. Firlit during the projected operating life of the Rancho Seco reactor. These concerns could be resolvea by establishing the initial RTpts value for the material in accordance with Paragraph NB-2331 of the ASME Code Section III. Within 60 days please advise Mr. George Kalman, our project manager for Rancho Seco, of your efforts to resolve these concerns.

Sincerely, original signed by George W. Knighton, Director Project Directorate V Division of Reactor Projects - III, IV, Y and Special Projects

Enclosure:

As stated cc: Jim Taylor, B&W See next page DISTRIBUTION Docket File NRC & Local PDRs PD5 Reading GMHolahan ,

JLee GKalman OGC (for info only)

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1 Mr. Joe Firlit Rancho Seco Nuclear Generating j Chief Executive Officer, Nuclear Station i Sacramento Municipal Utility District i 14440 Twin Cities Road Herald, California 95638-9799 cc:

Mr. David S. Kaplan, Secretary Mr. John Bartus and General Counsel Ms. JoAnne Scott Sacramento Municipal Utility Federal Energy Regulatory Comission District 825 North Capitol Street, N. E.

6201 S Street Washingtdn, D.C. 20426 P. O. Box 15830 Sacramento, California 95813 Mr. Barclay S. Lew Pacific Gas and Electric Company Thomas A. Baxter, Esq. 77BealeStreet(333/A613)

Shaw, Pittman, Potts & Trowbridge San Francisco, CA 94106 2300 N Street, N.W.

Washington, D.C. 20037 Ms. Helen Hubbard P. O. Box 63 Mr. Steven Crunk Sunol, California 94586 Manager, Nuclear Licensing Sacramento Municipal Utility District Rancho Seco Nuclear Generating Station 14440 Twin Cities Road Herald, California 95638-9799 Mr. Robert B. Borsum, Licensing Representative Babcock & Wilcox Nuclear Power Division 1700 Rockville Pike - Suite 525 Rockville, Maryland 20852 Resident Inspector / Rancho Seco c/o V. S. N. R. C.

14440 Twin Cities Road Herald, California 95638 Regional Administrator, Region V U.S. Nuclear Regulatory Comission 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 Mr. Jack McGurk, Acting Chief Radiological Health Branch 1 State Department of Health Services  !

714 P Street, Office Building #8  !

Sacramente, California 95814 l Sacramento County l Board of Supervisors i 700 H Street, Suite 2450 '

Sacramento, California 95814 I

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MEETING MINUTES SUBJ: RANCHO SECO REACTOR VESSEL PRESSURIZED THERMAL SHOCK DATE: THURSDAY, JULY 14, 1988 LOCATION: NRC HEADQUARTERS, ROCKVILLE, MD PARTICIPANTS: STEVE RUTTER, SMUD C.Y. CHENG, NRC ART LOWE, B&W SAM LEE, NRC JIM TAYLOR, B&W PRYORN RANDALL, NRC MICHAEL MAYFIELD, NRC KEITH WICHMAN, NRC BARRY ELLIOT, NRC GEORGE KALMAN, NRC DISCUSSION: The meeting was requested by the NRC staff to discuss apparent discrepancies in the value for the pressurized thermal shock initial reference temperature (RTpts) for WF-70 weld material. The Rancho Seco USAR assumes O degrees F. as the initial RTpts (measured value not available). SMUD correspondence (2/23/88 Itr to E. Southard) and B&W publications (BAW-1975 and BAW-1920P) indicate that the initial RTpts may be 58 degrees F. If the initial RTpts is revised to 58 degrees F.,

the Rancho Seco reactor vessel would be subject to the screening criteria per 10 CFR 50.61 during the next several years.

B&W presented proprietary graphs which included initial RTpts

' test results for WF-70. Some of the test results indicated that the initial RTpts may be as high as 74 degrees F. When asked what their initial RjT ts estimate would be, based on available test results; B&W re ied that their best estimate is 23 degrees F. f A caucus by the NRC participants following the joint meeting concluded that (1) Based on the presented B&W test data, O degrees F. does not appear to be an appropriate initial RTpts (a higher temp.

would be expected).

(2) The NRC participants can not determine from the data presented what the initial RTpts should be.

(3) The NRC will continue to review this issue internally and send any additional conclusions to SMUD/B&W.

George Kalman

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