ML19246B740
| ML19246B740 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 06/28/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Hines E DETROIT EDISON CO. |
| References | |
| NUDOCS 7907180410 | |
| Download: ML19246B740 (1) | |
Text
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NUCLEAR REGULATORY COMMISSION
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,o GLEN ELLYN. ILLINOIS 60137 Docket No. 50-341 r-G..
The Detroit Edison Company ATTN:
Mr. Edward Hines, Assistant Vice President and Manager Quality Assurance 2000 Sciond Avenue Detroit, MI 48226 Gentlemen:
The enclosed It. 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, ct _ a L
[ ames G5 Kepp er 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 Commission Eugene B. Thomas, Jr.,
Attorney 7907180'410 36/l 203
U.S.
NUCLEAR REGULATORY COMMISSION OFTICE OF INSPECTION AND ENFORCEMENT REGION III e-.
EL.
June 28, 1979 IE Circular No. 79-12 (7906210065)
P0TENTIAL DIESEL CINERATOR TURBOCHARGER PROBLEM Description of Circu= stances:
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 serv.ce.
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 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 pump may stop 5 to 10 seconds before the engine receives a start signal; but the main bearing and piston cooling pump will i==ediately receive oil from the priced lube oil filter-cooler system thus providing a rapid buildup of engine lube oil pressure throughout the engine bearing and turbocharger systems.
A potential proble= 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 pu=p will flow only to the turbocharger bearings because of the lower viscosity of the hot lubricant. At this temperature, the circulating pump pressure will not reach 30 psi.
Until the lube oil cools to about 160 degrees I, no oil wil' 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 ocet time frame after a hot shotdown, lac)
DUPLICATE DOCUMENT engine damage. In the worst case of actually reach aperating speed, 900 P Entire document previo, sly entered established at the turbocharger thrus into system under:
i of the bearing metal so that cumulati 7 Q / /,
/A would result in a turbocharger failur i
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