ML19305C389
| ML19305C389 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 02/25/1980 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Counsil W CONNECTICUT YANKEE ATOMIC POWER CO. |
| References | |
| NUDOCS 8003280481 | |
| Download: ML19305C389 (6) | |
Text
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NUCLEAR REGULATORY COMMISSION e
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af WASHtNGTON, D. C. 20666 E
o#N February 25, 1980 Docket No. 50-213 Mr. W. G. Counsil. Vice President Nuclear Engineering and Operations Connecticut Yankee Atomic Power Company Post Office Box 270 Hartford, Connecticut 06101
Dear Mr. Counsil:
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 Information Notice with errata sheet is enclosed.
Westinghouse notified utility users of this potential problem on October 30, i
1979 a'nd 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 e
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 undenvay at Arkansas Nuclear One Unit 1
Beaver Valley Unit I 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, and documentation to the NRC cf your justification for conti.nued 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 of 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 Haddam Neck Plant 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.
8003280
Mr. W. G. Counsil February 25, 1980 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,
/
l rellu.M.se u s, Acting Director Division oMperating 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/ enclosures See next page 4
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Mr. W. G. Counsil February 25, 1980 cc w/enclosurcs:
Day, Berry & Howard U. S. Environmental Protection Counselors at Law Agency One Constitution Plaza Region I Office Hartford, Connecticut 06103 ATTN:
EIS COORDINATOR JFK Federal Building Superintendent Boston, Massachusetts 02203 Haddam Neck Plant RFD #1 Post Office Box 127E East Hampton, Connecticut 06424 Mr. James R. Himmelwright Northeast Utilitias Scrvic& Ccmpany P. O. Box 270 Hartford, Connecticut 06101 Russell Library 119 Broad Street Middletown, Connecticut 06457 Board of Selectmen Town Hall Haddam, Connecticut 06103 Connecticut Energy Agency ATTN:
Assistant Director Research and Policy Development Department of Planning and Energy Policy 20 Grand Street Hartford, Connecticut 06106 Director, Technical Assessment Division Office of Radiation Programs
( AW-459)
U. S. Environmental Protection Agency Crystal Mall #2 Arlington, Virginia 204f3 O
UNITED STATES ISINS NO.: 6870 NUCLEAR REGULATORY COMMISSION Accession No.:
OFFICE OF INSPECTION AND ENFORCEMENT s.*e-Q9fol505Y53 WASHINGTON, D.C.
20555 l
December 28, 1979 IE Information Notice No. 79-37 CRACKING IN LOW PRESSURE TURBINE DISCS l
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Description of Circumstances:
An anony: nous letter was received by the Director of the Office of Inspection and i
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
~ l stress corrosion cracking in Westinghouse 1800 rpm low pressure-turbine discs.
Westinghouse had made a presentation on the turbine disc cracking to electric utility executives on October 30, 1979.
Telephone discussions between the NRC staff and Westinghouse's Turbine Division,
on Novecber 20, 1979 established that cracking, attributed to stress corrosion phenomena, 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 anc are being imple-mented in the field. The Office of Inspection and Enforcement was also notified on Ncvember 20, 1979 that during the current overhaul of Commenwealth Edison's Zion Unit 1 LP turbine, ultrasonic examination revealed embeddec 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 We.ctinghouse, these bore cracks have 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 evaluated by Westinghouse.
m A cesting was held on December 17, 1979 between the NRC staff, Westinchouse and utility representatives to discuss the disc cracking problem, repair alter-natives, turbine missile evaluation, inspection tecnniques and piant inspection pricrities.
In response to the staffs' request, Westinghouse provided the staff an updated report en December 21, 1979 regarding the current field inspection program that included a list of nuclear power plants already inspected, recem-mended inspection scheduies 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 Bea:h 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 s=all crack in the No. 2 disc of LP Turbine No. 2.
An analysis by Westinghouse indicated that the observed crack will not attain critical dirensions
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during 28 additional conths of turbine operation.
The NRC staff is evaluating l
the turbine inspection results and analysis by Westinghouse.
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