ML19256B424
| ML19256B424 | |
| Person / Time | |
|---|---|
| Site: | 05000580, 05000581 |
| Issue date: | 06/28/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Ziants C OHIO EDISON CO. |
| References | |
| NUDOCS 7907100522 | |
| Download: ML19256B424 (1) | |
Text
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3.,, gg(',j NUCLEAR REGULATORY COMMISSION g
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799 ROOSEVELT ROAD g
GLEN ELLYN, ILLINOIS 63137 c-Pre-CPP g g 8 jg79 The-0hio Edison Company C~-
ATTN:
Mr. Charlie Ziants Chief Nuclear QA Engineer 76 South Main Street Akron, OH 44308 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, O,.
0)4-n0 8Ia,mesG.K'ephr%
Director
Enclosure:
IE Circular No. 79-12 cc w/ encl:
Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Harold W. Kohn, Power Siting Commission 83.'3 040 7 907100 5 aa
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- U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT REGION III e-C..
June 28, 1979 IE Circular No. 79-12 (7906210065)
POTENTI!.L DIESEL GFNERATOR TURBOCHARGER PLOBLEM 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 standbv service.
When an engine is in t.ne 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 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 primed to support a fast start.
If a power outage occurs, the oil circulating pump may stop 5 to 10 seconds before the engine receives a start signal; but the mein bearing and piston cooling pu=p will immediately 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 c' lating pu=p will flow only to the turbocharger bearings because of the r 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 vill 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 I time frame after a hot shutdown, lack of engine damage.
In the worst case of a re DUPLICATE DOCUMENT 830 04!
actually reach operating speed, 900 RPM, established at the turbocharger thrust be Entire document previously entered of the bearing metal so that cumulative da into system under:
vould result in a turbocharger failure.
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