ML19256B427
| ML19256B427 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 06/28/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Burstein S WISCONSIN ELECTRIC POWER CO. |
| References | |
| NUDOCS 7907100526 | |
| Download: ML19256B427 (1) | |
Text
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GLEN ELLYN, ILLINOIS 60137 M
Docket No. 50-266 Dgeket No. 50-301 G.
Wisconsin Electric Power Company ATTN:
Mr. Sol Burstein Executive Vice President Power Plants 231 West Michigan Milwaukee, WI 53201 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, n. ok~
u-ames G. Kep er Director
Enclosure:
IE Circular No. 79-12 cc w/ encl:
Mr. G. A. Reed, Plant Manager Central Files Director, NRR/DPM Director, NRR/ DOR C. M. Tremmel, ORB /NRR PDR Local PDR NSIC TIC Sandra A. Bast, Lakeshore Citizens for Safe Energy h3h Okb ecc.
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U.S. NUCLEAR REGULATORY COM11SSION OFFICE OF INSPECTION AND ENFORCEMENT REGION III r,
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June 28, 1979 IE Circular No. 79-12 (7906210065)
POTENTIAL DIESEL GENERATOR TURBOCHARGER PR03LEM Description of Circumstances:
The Electro-Motive Division (FMD) 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 warm oil to the turbocharger bearings at a flow rate of about 2 gpm.
Since the total oil pump flow rate is 6 gpm, 4 gpm is also circulsted, 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 pump may stop 5 to 10 seconds before the engine receives a start signal; but the main bearing and pisten cooling pump will immediately receive oil from the primed lube 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 temperature.
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 output of the circu-lating pump will flow only to the turbocharger bearings because of the lower viscosity of the hot lubricant. At this temperature, the circulating pump pressure vill not reach 30 psi. Until the lube oil cools to about 160 degrees
- 7. no oil will 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 will drain back to the engine sump via the lube oil scavenging pump, and some of the oil from the strainer box will be drawn into the cooler by the system vacuum that develops.
The result is that when a repeat fast start occurs time frame after a hot shutdown, lack of engine damage.
In the worst case of a re DUPLICATE DOCUMENT 835 047 actually reach operating speed, 900 RPM, established at the turbocharger thrust be Entire doctunent previously entered of the bearing metal av that cumulative d into system under:
vauld result in a turbocharger failure.
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