ML13316A034
| ML13316A034 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/11/1989 |
| From: | Guntrum B COOPER INDUSTRIES, INC. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| REF-PT21-89, REF-PT21-89-073-000 PT21-89-073-000, PT21-89-73, NUDOCS 8904240034 | |
| Download: ML13316A034 (2) | |
Text
Ehil ENERGY SERVICES GROUP INDUSTRI Api 31, 18 Director of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Station P1-137 Washington, D.C.
20555 Report #149
Dear Sir,
In accordance with the requirements of Title 10, Chapter 1, Code of Federal Regulations, Part 21, Energy Services Group, (ESG) a division of Cooper Industries hereby notifies the Commission of a potential defect in a component of a;DSRV Standby Diesel Genera tor. There exists a potential problem.with two crankshaft con necting rod journals as manufactured by Energy Services Group and provided as part of the diesel engine.
Energy Services Group has supplied this component with this potential defect to the following site:
UTILITY S11E SERIAL NO.
MODEL So. Cal. Edison San Onofre 75041/42 DSRV-20-4 In February of this year, So. California Edison reported a prob lem to us with two connecting rod bearing shells rotating approx imately 90 degrees on the crankshaft journal and shearing the aluminum locating dowels; these dowels are used for assembly pur poses only in properly locating the bearing shell split line. On further examination, it was noted that the shell rotation was in the opposite direction of engine rotation -
indicating that the rotation occurred during engine shutdown and rollback.
Bearing shell rotation can cause engine failure by either of 2 means 1) cutting off lube oil supply to the crank pin running surface or 2) operating in a position that is inherently weak, that is with the bearing shell split line aligned with the con necting rod center line. This places the cylinder firing pres sures to bear directly on the weakest point of the bearing shell and could result in bearing failure. Fortunately, this particu lar case was marginal enough to manifest itself but not to cause "CuQ any component failure.
A further examination of site records and Energy Services Group meD records shows that this bearing rotation had occurred several 00 ENTERPRISE ENGINE SERVICES 85th Avenue and Enterprise Way OM P 0. Box 2161 Oakland, CA 94621-0061 (415) 577-7400 AJAX COOPER-BESSEMER ENTERPRISE EN-TRONIC CONTROLS NORDBERG
- PENN, SUPERIOR
April 11, 1989 U.S. Nuclear Regulatory Commission Page 2 times since 1982 and always in the same engine throws, (No's 5 &
8).
Records further show that connecting rod bores, the crankpin journals and bearing shells had been measured repeatedly with results consistently within blueprint tolerances. Site personnel also changed out connecting rods and bearing shells in an attempt to isolate the problem.
After similar repeated inspections and tests with new bearing shells, So. California Edison and Energy Services Group were able to identify the root cause of this bearing rotation as high spots on the crankpin journals -
with corresponding low spots on the opposite side. This was observed during a blueing inspection with a specially manufactured gage with a close tolerance fit to the crankpin journal. Neighboring throws were also checked for fit using this gage and were found to be acceptable.
We have been unable to determine how this condition could have occurred. Our process of superfinishing these journals should not result in the high and low spots we have found. Neither is there any evidence of operating conditions that would have caused this.
No evidence of "counter-rotated" connecting rod bearing shells has been reported in any other Enterprise R4 series engines; in either commercial or nuclear standby services. Accordingly, it is our position that this is an isolated case on this one engine (S/N 75041).
Corrective action has been taken to hand rub the high spots down. The crankpins (#5 and #8) were then checked with the blueing gage and found to be acceptable. The engine was reassembled and operated successfully. No further action is required.
A copy of this letter will be forwarded to the Southern Califor nia Edison Company.
Our evaluation of this matter was concluded on April 10, 1989.
Sincerely, Bruce'.untrum Manager, Quality Assurance BCG/dfa cc.:
Southern California Edison 23 Parker Street Irvine, CA 92718 Attn.:
Q.A. Manager n.ENERGY SERVICES GROUP