ML19256B430
| ML19256B430 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 06/28/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 7907100530 | |
| Download: ML19256B430 (1) | |
Text
ga arco, q" l C gj UNITE D STATES o,h NUCLEAR REGULATORY COMMISSION y yg%
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REGION V
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1990 N. CALF 70RNIA BOULEVARD
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SUITF 202,V/ALNUT CREEK PLAZA V/ALNUT CR E E K, CAllFORNIA 94596 June 28,1979 Docket tio. 50-344 Portland General Electric Company 121 S. W. Salmon Street Portland, Oregon 97204 Attention: Mr. Charles Goodwin, Jr.
Assistant Vice President 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, u
/ m-r R. H. Engelken Director
Enclosures:
1.
IE Circular No. 79-12 2.
List of IE Circulars Issued in Last 12 Months cc w/ enclosures:
B. Withers, PGE F. Gaidos, PGE 835 052 f
q907100E30
UNITED STATES fiUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 June 28, 1979 IE Circular No. 79-C (7906210065) p0TEf/TIAL DIESEL GENERATOR TURBOCHARGER PROBLEM Dest.ription of Circunstances:
Thc Electro-Motive Division (EMD) of General Motors Corporation has recently idantified a potential failure mode of turbochargers used on EMD die: els in raclear plant standby service.
When an engine is in the normal standby node, the lubricating oil temperature is maintained at about 115 degrees F and the circulating oil punp supplies warm oil to the turbocharger bearings at a flow rate of about 2 gpn.
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 nay stop 5 to 10 seconds before the engine receives a start signal; but the main bearing and piston cooling pump will irrmediately receive oil frca 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 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 temperatura.
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 tine 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 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 within the abova 16 ni e n + ^ ' ' -
time frame after a hot shutdown, lac'
'l engine damage.
In the worst case of DUPLICATE DOCUMENT h.,') bJ actuall" reach operating speed, 900 established at the turbocharger thru-Entire document Previously entered of the bearing metal so that cumulat into system under:
would result in a turbocharger failu
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