ML19225A110
| ML19225A110 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point, Saint Lucie  |
| Issue date: | 06/28/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Robert E. Uhrig FLORIDA POWER & LIGHT CO. |
| References | |
| NUDOCS 7907180435 | |
| Download: ML19225A110 (2) | |
Text
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IIC-pa aeco UNITED ST ATES
'c, NUCLEAR REGULATORY COMMISSION
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JUN 2 81979 In Reply Refer To:
RI :JPO 335,.50 389 50-250, 50-251 Florida Power and Light Co=pany Attn:
R. E. L% rig, Vice President Advanced Systems and Technology P. O. Box 529100 Miami, Florida 33152 Gentlemen:
The enclosed IE Circular 50. 79-12, is forwarded to you for inforcation.
No written response is requir ed.
Should you have any questions related this office.
to your understanding of this natter, please coatact Sincerely, i-James P-0 ' Re il l,,
Director
Enclosures:
1.
IE Circular No. 79-12 2.
List of IE Circulars Issued in ' ast 12 Months 7 0 07180 t/39 322 07;
JUN 2 81979 t
Florida Power and Light Company cc w/cocl:
C. M. Wethy, Plant Manager Post Office Box 128 33450 Ft. Pierce, Florida Wat Veems, Assistant QA Manager Post Office Box 128 Ft. Pierce, Florida 33450 Manager E. E. Yaeger, Plant Post Office Box 013100 Mise 2, Florida 33101 f
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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 June 28, 1979 IE Circular No. 79-12 (7906210065)
POTENTI AL DIESEL GEKERATOR TURBOCRARGER 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 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 main bearing and piston cooling pump will immediately receive cil 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 /> af ter 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 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 sill 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 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 of prime oil system pressure can cause engine damage.
In the worst case of a repeat fast start, the engine may actually reach operating speed, 900 RPM, before the required oil pressure is established at the turbocharger thrust bearing.
This may cause some smearing of the bearing metal so that cumulative damage from several similar starts would result in a turbocharger failure.
3J22 073
t IE Circular No. 79-12 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 recommended 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 arsure 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 tc 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 concurrently.
Where it is necessary to run the redundant diesels concurrently, maintain one diesel in the running mode for a minimum 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 required.
If you require additional information regarding this subject, contact the Director of the appropriate nRC Regional Office.
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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 BWR 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 BWR 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 In 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 78-16 UL Fire Test 11/6/78 All Holders of Reactor OLs or cps 78-19 Manual Override (Bypass) 12/28/78 All Holders of of Safety Actuation Signals cps 322 0/5
i IE Circular No. 79-12 Enclosure June 28, 1979 Page 2 of 3 LISTING OF IE CIRCULARS ISSUED IN LAST TWELVE 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 Teletherapy Medical Licensees and each Radi opha rma ceut i ca l Suppliers 79-02 Failure of 120 Volt Vital 2/16/79 All Holders of AC Power Supplies Reactor OLs and cps 79-03 Inadequate Guard Training-2/23/79 All Holders of Qualification and Falsified and applicants Training Records 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 Wire 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 Reactor Recirculation BVR 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 NEC 79-09 Occurrences of Split or 6/22/79 All Materials Punctured Regulator Diaphragms Priority I, Fuel In Certain Self Contained Cycle and Operating Breathing Apparatus Reactor Licensees
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IE Circular No. 79-12 Enclosure June 28, 1979 Page 3 of 3 LISTING OF 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 322 0l.