ML19246B726
| ML19246B726 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Byron, Braidwood, Quad Cities, Zion, LaSalle  |
| Issue date: | 06/28/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 7907180392 | |
| Download: ML19246B726 (1) | |
Text
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UNITED STATES POR 8[y,, g(,j NUCLEAR REGULATORY COMMISSION
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s REGION lli Shh 799 ROOSEVELT ROAD e
GLEN ELLYN, ILLINOIS 60137 JUN 2 81979 Docket Nos. 50-10, 50-237, 50-249, 5&-254, 50-265, 50-295, 50-304, 50-373, G-50-374, 50-454, 50-455, 50-456 and 50-457 Commonwealth Edison Company ATTN:
Mr. Byroa Lee, Jr.
Vice President Post Office Box 767 Chicago, IL 60690 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, e b MA JamesG.Kephr_A Director
Enclosure:
IE Circular No. 79-12 cc w/ encl:
Mr. B. B. Stephenson, Mr. R. Cosaro, Project Station Superintendent Superintendent Mr. N. Kalivianakis, Central Files Station Superintendent Director, NRR/DPM Mr. N. Wandke, Station Director, NRR/ DOR Superintendent PDR Mr. L. J. Burke, Site Local PDR Project Superintendent NSIC Mr. T. E. Quaka, Quality TIC Assurance Supervisor Anthony Roisman, Esq.,
Mr. R. H. Holyoak, Station Attorney Superintendent Mr. Dean Hansell, Office Mr. Gunner Sorensen, Site of Assistant Attorney Project Superintendent General
.,8 7 907T8 0 3 92 364 15E
U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT REGION III
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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 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 mode, the lubricating oil temperature is maintained at about 115 degrees F and the circulating oil pu=p 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 prime.d 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 pump will i= mediately receive oil from 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 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 pump will flow only to the turbocharger bearings because of the lower viscosity of the hot lubricant. At this temperature, the circulating pump pressure vill not reach 30 psi. Until the lube oil cools to about 160 degrees 7, 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 period some of the oil contained in the cooler and filter will drain back to 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 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 fra=e af ter a hot shutdown, lack of pri:;,;H N-e
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engine da= age.
In the worst case of a repeat actually reach operating speed, 900 RPM, befc DUPLIC'LTE DOCUMENT established at the turbocharger thrust bearit of the bearing =etal so that cumulative da=ag
? Entire document previously entered would result in a turbocharger failure.
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