ML19246B736
| ML19246B736 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 06/28/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Howell S CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 7907180405 | |
| Download: ML19246B736 (1) | |
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f 799 ROOSEVELT ROAD b3 GLEN ELLYN,ILLINOls 60137 JtJN 2 81979 Docket No. 50-329 Docket No. 50-330 c..
Consumers Power Company ATTN:
Mr. Stephen H. Howell Vice President 1945 West Parnall Road Jackson, MI 49201 Gentlemen:
The enclosed IE Circular No. 79-12, is forwarded to you for infor-mation. No written response is required. Should you have any questions related to your understanding of this matter, please contact this office.
Sincerely, W^r $ h n?%
(/ James G. K31fler Director
Enclosure:
IE Circular No. 79-12 cc w/ encl:
Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Ronald Callen, Michigan Public Service Ccmmission Dr. Wayne E. North Myron M. Cherry, Chicago
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U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT REGION III e-.
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June 28, 1979 IE Circular No. 79-12 (7906210065)
POTENTIAL DIESEL GENERATOR 'IURBOGtARGER PROBLEM Description of Circumstances:
The Electro-Motive Division (EMD) of General Motors Corporation has recently identified a potential failure mode of turbochargers used on EMD diesels, in nuclear plant standby service.
When an engine is in the normal standby mode, the lubricating oil temperature is maintained at about 115 degrees F and the circulating oil pump supplies varm oil to the turbocharger bearings at a flow rate of about 2 gpm.
Since the total oil pu=p flow rate is 6 gps, 4 gpm is also circulated, via a 30 psi relief valve, through the lube oil filter and cooler which serves to keep the entire accessory lubricating oil system primed to support a fast start.
If a power outage occurs, the oil circulating pu=p may stop 5 to 10 seconds before the engine receives a start signal; but the main bearing and piston cooling pu=p will i==ediately receive oil from the primed luce oil filter-cooler system thus providing a rapid buildup of engine lube oil pressure throughout the engine bearing and turbocharger systems.
A potential problem occurs, however, if the diesel engine receives a repeat rapid start within a minimum of 15 minutes and a maximum of 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after a shutdown from a previous run in which the engine has reached full operating te=perature.
If, for example, the engine had been operated for about I hour at full load, the lube oil temperature would be at about 200 degrees F at time of shutdown. Under these circumstances, the full 6 gpm cutput of the circu-lating pu=p vill flow only to the turbocharger bearings because of the lower visc.,sity of the hot lubricant. At this te=perature, the circulating pu=p pressure vill not reach 30 psi. Until the lube oil cools to about 160 degrees I, no oil vill be supplied via the relief valve to the equipment rack for the
.first 2 to 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after engine shutdown. During this cooling period some of the oil contained in the cooler and filter vill drain back to the engine sump via the lube oil scavenging pu=p, and some of the oil from the strainer box vill be drawn into the cooler by tha.avarem vacuum that develoos.
The. result is that when a repeat fast start o d time frame after a hot shutdown, la
!DUPLICATEDOCUMENT engine damage. In the worst case c actually reach cperating speed, 90C Entire document previously entered established at the turbocharger th:
1into system under:
of the bearing metal so that cumula t-would result in a turbocharger fa13
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ANO 7 f h [d h 5 / b b h 5 No. of pages:
3M 25
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