ML19246B738
| ML19246B738 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 06/28/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Linder F DAIRYLAND POWER COOPERATIVE |
| References | |
| NUDOCS 7907180408 | |
| Download: ML19246B738 (1) | |
Text
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UNITED STATES u
i NUCLEAR REGULATORY COMMISSION PDR l'h,,f I c 1% *f( 'Y REGION lli o, 42
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799 ROCsEVELT ROAD GLEN E LLYN, ILLINOls 60137
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JUN 2 81979 Docket No. 50-409 C'-
- DIiryland Power Cooperative ATTN:
Mr. F. W. Linder General Manager 2615 East Avenue - South La Crosse, WI 34601 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 er Director
Enclosure:
IE Circular No. 79-12 cc w/ encl:
Mr. R. E. Shimshak, Plant Superinteadent Central Files Director, hM/DPM Director, NRR/ DOR PDR Local PDP NSIC TIC Anthony Roisman, Esq.,
Attorney g
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7907180408
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U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT REGION III e
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June 28, 1979 IE Circular No. 79-12 (7906210065)
POTENTIAL DIESEL GENERATOR TURBOCHARGER PROBLEM Description of Circumstances:
The Electro-Motive Division (EMD) of General Motors Corpcration 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 gym.
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 pu=p may stop 5 to 10 seconds before the engine receives a start signal; but the main bearing and piston cooling pu=p will i= mediately receive oil from the primed lube oil filter-cooler system thus providir.g 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 frem 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 3G 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 /> af ter engine shutdown.
During this cooling neriod 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 vill be drawn into the cooler by the_ system vacuum that develops. The result is that when a repeat fast start occ1
""W 1* * "*a.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, lac
' DUPLICATE DOCUMENT engine da= age.
In the worst case of actually reach operating speed, 900 Ent' established at the turbocharger thr-u into sys em under:nt praviously entered of the bearing metal so that cumula vould result in a turbocharger fail ANO ] f M Q g[
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