ML19256B432
| ML19256B432 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 06/28/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| NUDOCS 7907100532 | |
| Download: ML19256B432 (1) | |
Text
,
f" ' %g
[g UNITED STATES
+7
,o, NUCLEAR REGULATORY COMMISSION E f y '.',g l
REGION V q
. p
- j 1990 N. CAllFOHNI A COULEVARD 0,
,, b" *
- o
SUITE 202, WALNUT CREEK PLAZA l
e g
- 't, g
WALNUT CRF EK, CALIFORNIA 9%6 i
June 28,1979 Docket tio. 50-312 Sacramento Municipal Utility District P. O. Box 15330 Sacramento, California 95813 Attention:
Mr. John J. Mattimoe Assistant General Manager Gentlemen:
The enclosed IE Circular flo. 79-12 is forwarded to you for information.
fio written response is required.
Should you have any questions related to your understanding of this matter, please contact this office.
Sincerely, j{'g]:,,,c'.5.-
R. H. Engelken Director
Enclosures:
1.
IE Circular flo. 7'-l?
2.
List of IE Circulars Issued in Last 12 Morths cc w/ enclosures:
R. J. Rodriguez, SMUD L. G. Schwieger, SMUD 836 056 79071005 %
Q
UflITED STATES NUCLEAR REGULATORY COMMIS! ION OFFICE OF IflSPECTION AND ENFORCEftENT WASHINGTON, D.C.
20555 June 28, 1979 IE Circular No. 79-12 (7906210065)
POTENTIAL DIESEL GENERATOR TURB0 CHARGER PROBLEM Description of Circumstances:
The Electro-Motive Division (EMD) of General fiotors Corporation has recently identified a potential failurt 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 gpm. Since the total oil pump flow rate is 6 gpr, 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 engire receives a start signal; but the main bearing and piston cooling pump will imediately receive oil from the primed lube oil filter-cooler system thus providing a rapid buildup of engine lube oil pressura 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 9pm 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 vacuuu. '+ develops. The result is that when a repeat fast start occurs within the abt 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 "2""N engine damage.
In the worst case of a DUPLICATE DOCUMENT 5 057 actually reach operating speed, 900 RP established at the turbocharger thrust Entire document previously entered of the baaring metal so that cumulativ into system under:
would rest 't in a turbocharger failure No. of pages:
[