ML19290E717
| ML19290E717 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/25/1980 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| NUDOCS 8003140440 | |
| Download: ML19290E717 (3) | |
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION l
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W ASHINGTON, D. C. 20555 5o S
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February 25, 1980 Docket No. 50-312 Mr. J. J. Mattimoe Assistant General Manager and Chief Engineer Sacramento Municipal Utility District 6201 S Street P. O. Box 15830 Sacramento, California 95813
Dear Mr. Mattimoe:
On December 28, 1979 the NRC Office of Inspection and Enforcement issued Information Notice No. 79-37 that presented information available to the staff related to the discovery of cracks in the keyway and bore sections of Westinghouse 1800 rpm low pressure turbines.
A copy of this Infornation Notice with errata sheet is enclosed.
Westinghouse notified utility users of this potential problem on October 30, 1979 and was requested by the staff to present a similar briefing in Bethesda, Maryland on December 17, 1979. You were contacted on December 14, 1979 and invited to send representatives to the staff briefing and also were requested to advise the staff of the actions being taken in regard to this potential problem at your operating nuclear power plant.
Westinghouse was later requested to meet again with the staff and licensee-users on January 8,1980 to supplement the information provided in the earlier meeting and in interim correspondence with the staff.
On the basis of information provided by Westinghouse and recent indications from turbine disc inspections now underway at Arkansas Nuclear One Unit 1, Beaver Valley Unit 1 and Indian Point Unit 2, it is evident that the probability of crack formation in these turbine discs is significantly greater than previously assumed by the vendor.
In light of this information and the actions being taken by the licensee-users, we consider this warrants your prompt full UT inspection of LP rotor discs, especially the keyways and bore areas, ano documentation to the NRC of your justification for continued operation until such inspections are made and all defects thus identified are corrected.
Therefore, in accordance with 10 CFR 50.54(f), you are requested to provide within 20 days of the date ef this letter, or in any event prior to restart if your unit is not operating, written statements, signed under oath or affirmation, which will enable the staff to determine whether or not your license to operate Rancho Seco should be modified, suspended, or revoked.
As part of your statement, you should provide and address the safety significance of the information requested in Enclosure 2 to this letter.
800314 0 QS-f Q P
Mr. J. J. Mattimoe Because of the general nature of the information sought in Enclosure 2 we are transmitting a copy of this enclosure to Westinghouse by separate letter.
As discussed in the December 17, 1979 meeting we urge you to address the generic aspects of this problem and to coordinate your responses through an owner's group.
- incerely, e
L i
Darrell sen us, c ing Director Division o perating Reactors
Enclosures:
1.
IE Information Notice No. 79-37 With Errata Sheet 2.
Request for Information Related to Turbine Disc Cracks - 20 Day Response cc:
w/enclosu res See next page
$ccramar.to Municipal Utility District cc w/ enclosure (s):
Christopher Ellison, Esq.
David S. Kaplan, Secretary and Dian Grueuich, Esc.
General Counsel California Energy' Commission 6201 S treet 1111 Howe Avenue P. O. Box 15830 Sacramento, California 95825 Sacramento, California 95813 Ms. Eleanor Schwartz Sacramento County California State Office Board of Supervisors 600 Pennsylvania Avenue, S.E., Rm. 201 827 7th Street, Room 424 Washington, D.C.
2C003 Sacramento, California 95814 Docketing and Service Section Business and Municipal Department U. S. Nuclear Regulatory Commission Sacramento City-County Library Washington, D.C.
20555 828 Street Sacramento, California 95814 Director, Technical Assessment Division Office of Radiation Programs Dr. Richard F. Cole (AW-459)
Atomic Safety and Licensing Board U. S. Environmental Protection Agency Panel Crystal Mall #2 U. S. fluclear Regulatory Commission Arlington, Virginia 20460 Washington, D.C.
20555 U. S. Environmental Protection Agency Mr. Frederick J. Shon Region IX Office Atomic Safety and Licensing Board ATTN:
EIS COORDINATOR Panel 215 Fremont Street U. S. Nuclear Regulatory Commission San Francisco, California 94111 Washington, D.C.
20555 Mr. Robert B. Borsum Elizabeth S. Bowers, Esq.
Babcock & Wilcox Chairman, Atomic Safety and duclear Power Generation Division Licensing Board Panel Suite 420, 7735 Old Georgetown Road U. S. Nuclear Regulatory Commission Lethesda, Maryland 20014 Washington, DC 20555 James S. Reed, Esq.
Thomas Daxter, Esq.
Michael H. Remy, Esq.
Shaw, Pittman, Potts & Trowbridge Reed, Samuel & Remy 1800 M Street, ?!W 717 K Street, Suite 405 Nashington, D. C.
2003G Sacramento, California 95814 Herbert H. Brown, Esq.
Mr. flichael R. Eaton Lawrence Coe Lanpher, Esq.
Energy Issues Coordinator Hill, Christopher and Phillips, P. C.
Sierra Club Legislative Office 1900 M St., NW 1107 9th St., Room 1020 Washington, D. C.
20036 Sacramento, CA 95814
Sacramento Municipal Utility District cc w/ enclosure (s):
Atomic Safety and Licensing Board Panel U. S. Nuclear Regulatory Commission Washington, D.C.
20555 Atomic Safety and Licensing Appeal Board Panel U. S. Nuclear Regulatory Commission Washington, D.C.
20555 fir. Richard D. Castro 2231 K Street Sacramento, California 95814 Mr. Gary Hursh, Esq.
520 Capital Mall Suite 700 Sacramento, California 95814 California Department of Health ATTN:
Chief, Environmental Radiation Control Unit Radiological Health Section 714 P Street, Room 498 Sacramento, California 95814
UNITED STATES ISINS NO.:
6870 NbCLEAR REGULATORY' COMMISSION Accession No.:
OFFICE OF IMPECTION AND ENFORCEMENT 7910250525 WASH E ON, D.C.
20555 December 28, 1979 IE Information Notice No. 79-37 CRACKING IN LOW PRESSURE TURBINE DISCS Description of Circumstances:
An anonymous letter w:ts received by the Director of the Office of Inspecti:n and Enforcement, on November 17, 1979 which alleged possible violation of Part 10 CFR 50.55e and/or 10 CFR 21 Regulations concerning reportability of recently discovered stress corrosion cracking in Westinghouse 1800 rpm low pressure turbine discs.
Vestinghouse had made a presentation on the turbine t.iisc cracking to electric utility executives on October 30, 1979.
Telephone discussions between the NRC staf f and Westinghouse's Turbine Division on November 20, 1979 established that cracking, attributed to stress corrosion phencrena, had been found in the keyway areas of several LP turbine discs at operating plants and that inservice inspection techniques (i.e., in situ ultra-sonic exa.ination) for crack detection have been developed and are being imple-cented in the f '. eld.
The Office of Inspection and Enforcenent was also notified on No.c:.be r 20, 1979 that during the current overhaul of Commonwealth Edison's Zion Unit 1 LP turbine, ultrasonic examination revealed embedded cracks located on the inlet side on the disc bore area where no cracks had been previously observed.
Ultrasonic measurements indicate this disc bore cracking is of greater depth than the keyway cracks found to date.
According to Westinghouse, these bore cracks tiave been metallurgically examined and preliminary findings show them not to be typical of classical stress corrosion cracking observed in the keyways.
The probable cracking mechanism and impact on disc integrity is being further evaluatect by Westinghouse.
A meeting was held on December 17, 1979 between the NRC staff, Westinghouse and utility representatives to discuss the disc cracking problem, repair alter-natives, turbine missile evaluation, inspection techniques and plant inspection priorities.
In Jasponse to the staffs' request, Westinghouse provided the staff an updated report on December 21, 1979 regarding the current field inspection program that included a list of nuclear power plants already inspected, recom-canced inspection schedules and pertinent information related to LP turbines where cracks have been observed.
Inspections to date have identified turbine disc cracks at Surry Unit 2, Point Beach Unit 2, Palisades, Indian Point Unit 3 and Zion Unit 1.
All units except Point Beach Unit 2 will make repairs before the plants return to power.
Point Beach returned to power on December 23, 1979 with a small crack in the No. 2 disc of Vestinghouse indicated that the observe during 28 additional conths of turbine DUPLICATE DOCUMENT the turbine inspection results and anal Entire document previously entered into system unde fh hNO
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