ML19246B732
| ML19246B732 | |
| Person / Time | |
|---|---|
| Site: | Zimmer |
| Issue date: | 06/28/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Borgmann E CINCINNATI GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7907180400 | |
| Download: ML19246B732 (1) | |
Text
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UNITED STATES l'S NUCLEAR REGULATORY COMMISSION PDR
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REGION lit o,
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799 ROOSEVELT ROAD s/
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GLEN ELLYN, ILLINOIS 60137
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JUN 2 81979 Docket No. 50-358 e-G.
Cincinnati Gas rnd Electric Company ATTN:
Mr. Earl A. Lorgmann Vice President Engineering Services and Electric Production 139 East 4th Street Cincinnati, OH 45201 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, p. 9, g ~ 0
(/JamesG'.Ke[pfer Director
Enclosure:
IE Circular No. 79-12 cc w/ encl:
Mr. J. R. Schott, Plant Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Harold W. Kohn, Power Siting Commission Citizens Against a Radioactive Environment Helen W. Evans, State of Ohio
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U.S. NUCLET REGULATORY CCMMISSION OFFICE OF INSPECTION AND ENFORCEMENT REGION III Cu.
June 28, 1979 IE Circular No. 79-12 (7906210065)
POTENTIAL DIESEL GENERATOR '"UR30 CHARGER PROBLEM I)escription 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 la in the normal standby mode, the lubricating oil temperature is maintained c,.t 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 aisc 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 circulsting pump may stop 5 to 10 seconds before the engine receives a start si;;nal; but the main bearing and piston cooling pu=p will i==ediately receive oil frcu 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 mini =um 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 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 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 te the engine sump via the lube oil scavenging pu=p, and some of the oil from the strainer box will be drawn into the cooler bp
- 7 - +- v ynum.that develoos. The result is that when a repeat fast star
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time frame after a hot shutdown DUPLICATE DOCUMENT engine damage.
In the worst ca I' actually reach operating speed, Entire document previously entered established at the turbocharger into system under:
of the bearing metal so that et
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