ML19225A112
| ML19225A112 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 06/28/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Stampley N MISSISSIPPI POWER & LIGHT CO. |
| References | |
| NUDOCS 7907180439 | |
| Download: ML19225A112 (2) | |
Text
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/f a a n c gc, UNITED ST ATES E ',
- CLEAR REGUL ATORY COMMISSION
$l' E
REGION 11 i'
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101 M ARIE T T A ST. N W, SUIT E 3100 ATL ANT A. GE oRGI A 30303 6,,
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3 JUN 2 81979 In Reply Refer To:
RII:JPO 50-416, 50-417 Mississippi Power and Light Company Attn:
N. L. Sta=pley Vice President of Production P. O. Box 1640 Jackson, Mississippi 39205 Gentlemen:
The enclosed IE Circular So. 79-12, is forwarded to you for infornation-No written response is required.
Should you have any questions related contact this office.
to your understanding of this natter, please Sincerely,
- i-James P. O'Feilly s,
Director Enclosures.
1.
IE Circular So. 79-12 2.
List of IE Circulars Issued in Last 12 Months 3'l 7907130ff,39
AIN281979 5
Mississippi Power and Light Company cc w/ encl:
C. K. McCoy Plant Manager Post Office Box 756 39250 Port Gibson, Mississippi O
e 4
3/i/
007
UNITED STATES NUCLEAR REGULATORY COMMISSION p
0FFICE OF INSPECTION AND ENFORCEMENT (s4 WASHINGTON, D.C.
20555 June 28, 1979 IE Circular No. 79 (7906210065)
POTENTI AL DIESEL GENERATOR TURBOCHARGER PROBLEM Description of Circumstances:
The Electro-Motive Division (EMT) 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 circu?ating 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 pst relief valve, through the lube oil filter and cooler which serves to Leep the entire accessory lubricating oil syste= primed to support a fast start.
If a power '>utage occurs, the oil circulating pump may stop 5 to 10 seconds before the engine receives a start signal, but the main bearing and piston cooling pump will immediately receive oil from the primed lube oil filter-cooler system thus providing a rapid buildup of engine lube oil pressure throughout
'he 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 /> af ter a srutdown from a previous run in which the engine has reached full operating temperiture.
If, for example, the engine had been operated for about I hour at full load, the lube eil temperature would be at about 200 degrees F at time of shutdown.
Undet 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 circulatit g 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 /> af ter engine shutdosm During this cocling period some of tlc oil contained in the cooler and filter will drain back tr 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 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 afte-a hot shutdown, lack of prise oil system pressure can cause engine damage.
In the worst case of a repeat fast start, the engine say actually reach operating speed, 900 RPM, before the required oil pressure is established at the turbocharger thrust bearing.
Thi say cause some sacaring of the bearing actal so that cumulative damage from several similar starts would result in a turbocharger failure.
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IE Circular No. i9-12 June 28, 1979 Page 2 of 2 EMD is currently developing a modification to improve the lube oil system.
It is planned that this modification will be available for installation in approximately 6 months.
In the interim, the following actions are recomm nded for those having EMD diesel engines:
1.
Repeated fast hot starts within a minimum 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 shutdown should be avoided.
Allow the engine to cool at least 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after it has been operated in the loaded" mode, or otherwise a restart should be performed within 15 minutes of shutdown.
2.
After changing oil filter elements or draining the accessory oil system for any reason, and upon refilling of the system make sure that the circu-lating oil pump is in operation for at least 30 minutes and that the strainer box is full before starting engine.
The engine should then be brought to an idling condition to assure complete filling of accessories before any subsequent fast start is made.
3.
Any small leak at the top of the oil cooler should be corrected.
A leak at this location allows air to be drawn into the cooler during shutdown, which will cause the drain back to be more rapid.
4.
Avoid testing of the redundant diesel engines concur -ntly.
Where it is necessary to run the redundant t iesels concurrently, warntain one diesel in the running mode for a minimuu of 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> following the shutdown of the other.
No written response to this Circular is requireo.
If you require additional inf o rmation rega rding this subj ect, contact the Director of the appropriate h'RC Regional Office.
347 309
IE Circular No. 79-12 Enclosure June 28, 1979 Page 1 of 3 LISTING OF IE CIRCULARS ISSUED IN LAST TWELVE MONTHS Circular Subject Date Issued To No.
of Issue 78-12 HPCI Turbine Control 6/30/78 All Holders of Valve Lift Rod Bending BVR OLs or cps for plants with HPCI Terry Turbine 78-13 Inoperability of Multiple 7/10/78 All Holders of Service Water Pumps Reactor OLs and cps except for plants located in: AL, AK, CA, FL, GA, LA, MS, SC 78-14 HPCI Turbine Reversing 7/12/78 All Holders of BWP Chamber Hold Down Bolting OLs or cps for plants with a HPCI Terry Turbine excepting Duane Arnold and Monticello 78-15 Checkvalves Fail to 7/20/78 All Holders of Close :o Vertical Reactor OLs or cps Position 78-16 Limitorque Valve 7/26/78 All Holders of Actuators Reactor OLs or cps 78-17 Inadequate Guard Training /
10/13/78 All Holders of Qualification and Falsified and applicants Training Records for Reactor OLs 78-18 UL Fire Test 11/6/78 All Holders of Reactor OLs or cps 78-19 Manual Override (Bypa s s )
12/28/78 All Holders of of Safety Actuation Signals cps 347 010
IE Circular No. 79-12 Enc osure June 28,1979 Page 2 of 3 LISTING OF IE CIRCULARS ISSUED IN LAST TNILVE MONTHS Circular Subject Date of Issued to No.
Issue 79-01 Administration of 1/12/79 All Holders of Unauthorized Byproduct Licensees except Material to Humans Teletberapy Medical Licensees and each Ra d i opha rma c e u t i c a l Suppliers 79-02 Failure of 120 Volt Vital 2/!6/79 All Holders of AC Power Supplies Reactor OLs and cps 79-03 Inadequate Guard Training-2/23/79 All I alders of Qualification and Falsified and applicants Training Fecords for Special Nuclear Material Licenses in Safeguards Group I 79-04 Loose Locking Nut On 3/16/79 All Holders of Limitorque Valve Reactor Ols or cps Operators 79-05 Moisture Leakage In 3/20/79 All Holders of Stranded Wir-Conductors Reactor OLs or cps 79-06 Failure to Use Syringe 4/19/79 All Holders of and Battle Shields in Medical Licensees Nuclear Medicine except teletherapy licensees 79-07 Unexpected Speed Increase 5/2/79 All Holders of of Reacto; Recirculation BVF OL's or CP's MG Set Resulted in Reactor Power Increase 79-08 Attempted Extortion - Low 5/18/79 All Fuel Facilities Enriched Uranium Licensed by Khi 79-09 Occurrences of Split or 6/22/79 All Materials Panctured Regulator Diaphrages Piiority I, Fuel In Certain Self Contained Cycle and Operating Breathing Apparatus Reactor Licensees 347 0 't 1
IE Circulat No. 79-12 Enclosure June 28, 1979 Page 3 of 3 LISTING 0F IE CIRCULARS ISSUED IN LAST TWELVE MONTHS Circular Subject Date of Issued to No.
Issued 79-10 Pipefittings Manufactured 6/26/79 All Power Reactor from Unacceptable Material Licensees with a CP and/or OL 79-11 Design / Construction 6/27/79 All Applicants Interface Problem for, and Holders of Power Reactor cps 347 012