RBG-20-746, Final Deficiency Rept DR-291 Re Ruptured 22 Gauge Crankshaft Plug on Standby Diesel Generator Supplied by Tdi.Initially Reported on 850318.All 22 Gauge Crankshaft Plugs Replaced w/16 Gauge Plugs

Final Deficiency Rept DR-291 Re Ruptured 22 Gauge Crankshaft Plug on Standby Diesel Generator Supplied by Tdi.Initially Reported on 850318.All 22 Gauge Crankshaft Plugs Replaced w/16 Gauge Plugs

ML20116F835
Person / Time
Site:	River Bend
Issue date:	04/17/1985
From:	Booker J GULF STATES UTILITIES CO.
To:	Martin R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
DR-291, RBG-20-746, NUDOCS 8505010256
Download: ML20116F835 (3)

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GULF STATES POST OFFICE BOX 2951 UTILITIES COMPANY

• DEAUMONT. TEXAS 77704 afb AREA CODE 713 838-6631 April 17, 1985 RBG 20,746 File Nos. G9.5, G9.25.1.1 Mr. Robert D. Martin, Regional Administrator U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 1000

@bbb Arlington, Texas 76011 M22E

Dear Mr. Martin:

/j River Bend Station Unit 1 Docket No. 50-458 Final Report /DR-291 On March 18, 1985, GSU notified Region IV by telephone of DR-291 concerning the crankshaft plugs on the standby diesel generators supplied by Transamerica Delaval, Incorporated. GSU had determined that DR-291 is reportable under 10CFR50.55(e). The attachment to this letter is GSU's final 30-day written report pursuant to 10CFR50.55(e)(3) with regard to this deficiency.

Sincerely,

, eYK J. E. Booker Manager-Engineering, 85050 DR OM $h h 58 PDR Nuclear Fuels & Licensing River Bend Nuclear Group h hc>

JEB/PJD/lp Attachment cc: Director of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555 NRC Resident Inspector-Site f997 gg@ f I I

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ATTACHMENT April 17, 1985 RBG 20,746 DR-291/ Crankshaft Plugs on the Standby Diesel Generators Supplied by Transamerica Delaval, Incorporated i

Background and Description of the Problem On March 9, 1985, during a scheduled post test inspection of standby diesel generator A (1-EGS*EGIA) supplied by Transamerica Delaval, Incorporated (TDI), the proper oil flow inside the diesel engine was examined. The inspection revealed that the oil plug (TDI part No.

R-3149) in the No. I cylinder crankshaft throw was partially ruptured as described in Nonconformance and Disposition Report (N&D) No. 10,886.

The cylinder 1 plug was a 22 gauge plug.

The function of the crankshaft plug is to seal the entry hole drilled in the crankshaft to establish communication between the oil holes in the main bearing journal and the connecting rod bearing journal. In operation, lubricating oil is supplied under pressure of approximately 50 psig to the main bearing. A portion of the oil flows from the main bearing through the drilled passage to the connecting rod bearing. A drilled passage in the connecting rod supplied oil to the piston pin bushing, piston crown, and piston rings.

According to TDI, the original design of the crankshaft oil plug was released in December 1965 and called for the plug to be stamped from 16 gauge sheet metal which is approximately 60 mils in thickness. In March of 1980, the plug material was changed to 22 gauge sheet metal for " ease of assembly". Twenty-two gauge sheet metal is approximately 30 mils in thickness. TDI returned to the original 16 gauge material in June 1982 because of failures in other engines and shop experience indicating that the thinner material was more likely to be damaged during the installation process.

The concern with the 22 gauge plugs was identified by the TDI Diesel Generator Owner's Group, and a sample of two plugs was inspected at River Bend (cylinders 7 and 8 on standby diesel A). Both of these plugs were found to be 16 gauge plugs, which resolved the concern at that time.

All crankshaft plugs in both TDI diesel generators were dimensionally inspected. The remaining seven plugs in diesel A were found to be 16 gauge plugs. All eight plugs in diesel B were found to be 22 gauge plugs.

Page 2 April 17, 1985 RBG 20,746 The failed plug was returned to TDI for evaluation. The results on TDI's evaluation are not yet available; however, it can be concluded that the 22 gauge plugs failed as a result of low-cycle fatigue associated with repeated pressurization during engine starts and stops.

The failure is attributed to inadequate design and inadequate sampling during field preservice inspection.

Safety Implication The open area of the rupture was approximately 30 percent of the 15/16 inch diameter oil hole, producing an internal lubricating oil leak from the No. I cylinder to the engine sump. The leakage would reduce the lubricating oil flow to the No. 1 cylinder connecting rod bearing, and from there to the piston wrist pin bushing, piston crown, and piston rings. If the failure had remained uncorrected, further operation could have resulted in failure of the remaining portion of the plug, and a greatly increased leakage flow. Therefore, it is conservatively assumed that if the failure had remained uncorrected after the post test inspection, then standby diesel A could have become inoperable in subsequent operation thereby adversely affecting the safe operation of the plant. The same condition might have occurred on diesel generator B, since it also had 22 gauge plugs.

Corrective Action Crankshaft plugs were 100% dimensionally inspected,'and all 22 gauge plugs were removed and replaced with 16 gauge plugs, using TDI factory personnel and tooling.

Standby diesel generator A was given a series of tests and inspections to detect possible consequential damage prior to return to service, as described in N&D 10,886. No damage was detected.