ML19329E409
| ML19329E409 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 12/17/1974 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Howell S CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 8006120735 | |
| Download: ML19329E409 (1) | |
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UNITED STATES j
ATOMIC ENERGY COMMISSION e <j.
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DIRECTORATE OF REGULATORY OPERATIONS 4s @ "A o
REGION lli 799 ROOSEVELT ROAD mg GLEN ELLYN, ILLINOIS 60137 (3 t z) 858-2660 "C
1 7 1974 J
Ceasemore Power Campany Doeket Me. 50-329 ATTN Mr. Stephen E. Howell Deeket No. 50-330 Vice President 1945 Perna 11 Road Jeeksen, M4 94-==
49201 GeaHm===
The emeleoed RD Ballatin regneste estion by you with regard to your power reactor facilities with operating 14e==== or cemetracties permit.
Shemld you have questises resording this Bulletin or eetiene requested of you, pines matase this offie sincerely, James G. Esppler Regional Director Emelesere RO Bellatin 74-16 THIS DOCUMENT C0i1TAINS POOR QUALITY PAGES Approved by GAO, B-180225 (R0072), clearense espirse 7/31/77.
- .pproval was siven under a bleaket clearance specift,mity for identified generie problems.
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r December 17, 1974 DRO Bulletin No. 74-16 IMPPOPER MACHINING.0F PISTONS IN COLT INDUSTRIES (FAIRBANKS-MORSE)
DIESEL-GENERATORS We recently received information from Northeast Nuclear Energy Company (NNECO), Baltimore Gas and Electric Company (BG&E), and Colt Industries describing a deficiency in the machining of pistons in a Fairbanks-Morse emergency diesel generator, type H7B.
DESCRIPTION OF CIRCUMSTANCES:
NNECO reported that the four capscrews retaining a piston insert in an upper piston of the diesel engine had broken away and were found lying in the engine crankcase. The capscrews were found during a routine field inspection prior to operating the equipment.
NNECO's and Colt Industries' investigations indicated that the cause of the failure was improper machining of the underside of the piston crown, The improper machining left an elevated, ring-shaped surface inside the i
piston. This prevented the piston and piston insert from mating properly.
As a result, during the compression cycle, the resultant space between the surfaces of the two parts allowed the piston crown to flex and be forced down on the insert surface. This subjected the capscrews to an alternating stress, causing their eventual failure.
During the inspection of the remaining pistons, two other pistons were found with the same machining error. However, the capscrews in these pistons had not failed.
BG&E reported that they had found two incorrectly machined pistons.
In addition, they found that several locking strips, which are attached to each pair of-capscrews, had cracked at the bolt-hole locations, f
Colt Industries stated that,the probable cause of the failure of the locking strips was an improper torque sequencing of the capscrews during installation.
Colt industries indicated that they have initiated a program, directed by their service representatives, to inspect all diesel generators in the field that could have these-conditions.
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2-R0 Bulletin 74-16 ACTION REQUESTED OF LICENSEES:
1.
Notify this office in writing within 20 days whether engines of the make and type described above are used at your nuclear power facilities with operating license or construction permit.
2.
If engines of this make and type are used, your written reply to item 1 above should include your schedule for examination of the potentially affected engines.
3.
Upon completion of any required examinations, provide to this office, in veriting within 30 days, the results of the examinations and a description of any repairs found to be necessary.
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