ML19290E757
| ML19290E757 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 02/25/1980 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Lundvall A BALTIMORE GAS & ELECTRIC CO. |
| References | |
| NUDOCS 8003140482 | |
| Download: ML19290E757 (3) | |
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<k At 40 cic ckc6 UNITED STATES y
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NUCLEAR REGULATORY COMMISSION j
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February 25, 1980
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Docket No. 50-318 gi
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Mr. A. E. Lundvall, Jr.
0 90 Sg\\N y 3 Vice President - Supply j
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Baltimore Gas & Electric Conpany 67
( M sd* Y P. 0. Box 1475
- ha Baltimore, Maryland 21203
Dear Mr. Lundvall:
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 Infor-mation 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 Poir,t Unit 2, it is evident that the proba-bility 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 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 of this letter, or in any event prior to restart if your unit is not operating, written statements, signed under oath or affiratier., which will enable the staff to determine whether or not your license to operate Calvert Cliffs Unit No. 2 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.
U 8 ava n um
Mr. A. E. Lundvall, Jr. 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,
f-r senhu., n t ng Director Da e i u.
Division of 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/ enclosures See next page
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3altinare Gas L Electric Company e
cc:
Janes A. Biddison, Jr.
Mr. R. M. Douglass, Manager General Counsel Quality Assurance Department G and E Builcing Room 923 Gas & Electric Building Charles Center P. O. Box 1475 Baltimore, Maryland 21203 Baltimore, Maryland 21203 di George F. Trowbridge, Esquire ggg.
Shaw, Pittman, Potts and gd.gg Trowbridge ici.
1800 M Street, H.U.
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Washington, D. C.
20036 lir. R. C. L. Olson Baltinore Gas and Electric Company Room 922 - G and E Building Post Of fice Box 1475
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Bal tinore, Maryland 21203
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fir. Leon B. Russell, Chief Engineer Calvert Cliffs Nuclear Power Plant
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Baltinore Gas and Electric Company Lusoy, Maryland 20657 r
Bechtel Power Corporation ATTH:
Mr. J. C. Judd Chief Nuclear Engineer 15740 Shady Grove Road Gaithersburg, Maryland 20760 Conbustion Engineering, Inc.
ATTM-fir. P. W. Kruse, flanager
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Engineering Services
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Post Office Box 500 Winasor, Connecticut 06095 2.-
Calvert County Library Princs Frecerick, Marylanc 20670 e.eme.no s eee.
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UNITED STATES ISINS NO.: 6870 NUCLEAR REGULATORY' COMMISSION A: cession No.:
OFFICE OF INSPECTION AND ENFORCEMENT 7910250525 VASHINGTON, D.C.
20555 December 28, 1979 IE Information Notice No. 79-37 CRACKING IN LOW PRESSURE TURSINE DISCS Description of Circumstances:
An anonymous letter was received by the Director of the Office of Inspection 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.
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 November 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 examination) for crack detection have been developed and are being imple-canted in the field.
The Office of Inspection and Enforcement was also notified on November 20, 1579 that during the current overhaul of ".ommonwealth Edison's Zion Unit 1 LP turbine, ultrascnic examination revealed enbedded cracks located on the inlet side on the disc bore area where no cracks had been previously obs e rved.
Ultrasonic measurements indicate this disc bore cracking is of greater depth than the keyway cracks found to date.
According to Westinghouse, 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 mecnanism and impact on disc integrity is being further evaluate:1 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-catives, turbine issile evaluation, inspection techniques and plant inspection priorities.
In response to the staffs' re:;c St, Westinghouse provided the staff an updated report on December 21, 1979 regarding the current field inspection progra= that included a list of nuclear power plants already inspected, recom-manced inspection schedules and pertinent information related to LP turbines where cracks ha+2 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 ret n
ow r on Dec 14 o with a small crack in the No. 2 disc o Vestinghouse indicated that the observ DUPLICATE DOCUMENT during 28 additional conths of turbine the turbine inspection results and ana Entire document previously entere into system under-ANO h
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