ML19256B433
| ML19256B433 | |
| Person / Time | |
|---|---|
| Site: | Columbia, Washington Public Power Supply System, Satsop  |
| Issue date: | 06/28/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Strand N WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| References | |
| NUDOCS 7907100534 | |
| Download: ML19256B433 (1) | |
Text
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o UNITED STATES 8
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NUCLEAR REGULATORY COMMISSION 7,
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1990 N. CAllFORNI A COULEVARD
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SUITE 202, WALNUT CREEK PLAZA 4+,,*
WALNUT CHEE K CALIFORNIA 94593 June 28, 1979 Docket flos. 50-460, 50-397, 50-508, 50-509, 50-513 Washington Public Power Supply System P. O. Box 968 3000 George Washington Way Richland, Washington 99352 Attention: Mr. N. O. Strand Managing Director Gentlemen:
The enclosed IE Circular No. 79-12 is forwarded to you for information.
flo written response is required.
Should you have any questions related to your understanding of this matter, please contact this office.
Sincerely,
/h77-u_e,c4b__
d R. H.-Engelken Director
Enclosures:
1.
IE Circular No. 79-12 2.
List of IE Circulars Issued in Last 12 Months cc w/ enclosures:
M. E. Witherspoon, WPPSS A. D. Kohler, WPPSS J. P. Thomas, WPPSS W. J. Talbott, WPPSS G. C. Sorensen, WPPSS 835 058 2eonoorsf
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMEfiT WASHINGTON, D.C.
20555 June 28, 1979 IE Circular No. 79-12 (7906210065) p0TENTIAL DIESEL GENERATOR TURB0 CHARGER PROBLEM Description of Circunstances:
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 code, the lubricating oil temperature is maintained at about 115 degrees F and the circulating oil pump supplies warrr oil to the turbocharger bearings at a flow rate of about 2 9pn.
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 systen primed to support a fast start.
If a power outage occurs, the oil circulating pump nay stop 5 to 10 seconds before the engine receives a start signal; but the main bearing and piston cooling pump will immediately receive oil from the prined 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 naximum 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 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 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 will not reach 30 psi.
Until the lube oil cools to about 160 degrees F, no oil will be supplied via the relief valve to the equiprent 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 within the above 15 minute to 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> time frame after a hot shutdown, lack af prime oil system pressure can cause engine damage.
In the worst case of actually reach operating speed, 900 F DUPLICATE DOCUMENT 8j$ [j]
established at the turbocharger thrus of the bearing metal so that cumulati Entire document previously entered would result in a turbocharger failut into system under:
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