ML19225A120
| ML19225A120 | |
| Person / Time | |
|---|---|
| Site: | Atlantic Nuclear Power Plant  |
| Issue date: | 06/28/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Collier A OFFSHORE POWER SYSTEMS (SUBS. OF WESTINGHOUSE ELECTRI |
| References | |
| NUDOCS 7907180447 | |
| Download: ML19225A120 (1) | |
Text
f d' p "'cwc, UNITED ST ATES NUCLE AR REGUL ATORY COMMISSION 8 'I
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c 101 M ARIE TT A ST to u. sutT E 3100 b((f o,
ATL ANT A GEORGI A 30303 "s,,
JJN 2 8 f979 In Reply Refer To:
RII:JPO 56 437 Of f shore Pcwer Systeus Attn:
A. 3. Collier, President P. O. Box 8000 Jacksonvfile, Florida 32211 Gentlene1:
The en'.losed IE Circular :;o. 79-12, is foncarded to you for information.
No written response is required.
Should you have any questions related this office.
to ',our un 4 rstanding of this natter, please contact Sincerely,
~
i -},
Janes P. O'Reilly Director
Enclosures:
1.
IE Circular :;o. 79-12 2.
List of IE Circulars Issued in Last 12 Months t
79 0'7180 g 7 347 053
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 June 28, 1979 IE Circular No. 79-12 (7906210065)
PC.tNTI AL DIESEL GEVERATOR 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 pump supplies warm oil to the turbocharger bearings at a flow rate of about 2 gpe.
Since the total oil pump flow rate is 6 gpe, 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 recei"es a start signal, but the main bearing and piston cooling pu=p will immediately receive oil f rom 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 bours 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 circi-lating pump will flow only to the turbocharger bearings b-ause of the lower viscosity of the bot 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 shutdovn During this cooling period some of the oil contained in the cooler and filter will drain back to the engine s ue; via the lube oil scavenging purp, and some of the oil from the strainer box will be drawn anto the cooler by the system vacuum that develops.
The result is that when a repeat fast start occurs within the sbove 15 minute to 3 bour time f rame af ter a bot shutdown, lack of prise ott 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 sacaring of the bearing metal so that cumulative damage from several similar starts would result in a turbocharger failure.
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IE Circular No. 79-12 June 26, 1979 Page 2 of 2 EMD is currently developing a mod 2fication 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 f ollowing actions are recommer.ded for those having EMD diesel engines:
1 Repeated fast bot 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 f rame after shutoswn 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 concurrently.
Where it is redundant diese.s concurrently, maint <n one diesel l
necessary to run the in the running mode for a mirtmum 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 inf ormation regarding this subject, contact the Director of the appropriate NRC Regional Office.
7 7
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IE Circular No. 79-12 Enclosure June 28, 1979 Page 1 of 3 LISTING OF IE CIRCU! ARS ISSED IN LAST TVEIXE 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 witt.
HPCI Terry Turbine 78-13 Inoperability of Multiple 7/10/78 All Holders of Service Water Pumps Ileactor OLs and cps except for plants loc 2ted in: AL, AK, CA, FL, GA, LA, MS, SC 78-14 HPCI Turbine Reversing 7 /12 / ,
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 Chetxvalves Fa.1 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 cuard Training /
10/13/78 All Holders of Qualification and Falsified end applicants Training Records for Reactor Ois 78-18 UL Fire Test 11/6/78 All Iders of Reactor OLs or cps 78-19 Manual Override (Bypass) 12/28/78 All Holders of Safety Actuation Signals cps Ilh hs pg ga w wa
IE Circular No. 79-12 Enclosure June 28,1979 Page 2 of 3 LISTING OF IE CIRCULARS ISSUED IN LAST TVELVE 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 Hutans Teletberapy Medical Licensees and each Ra di opha rma c e ut i c a 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 Motsture 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 Medical Licensees and Battle Shields in Nuclear Medicine except teletherapy licensees 79-07 Unexpected Speed increase 5/2/79 All Holders of of Reactor Recirculation BWE CL'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 NkJ ll Materials 79-09 Occurrences of Split or 6/22/79 e
Punctured Regulator Diaphrages
..nority 1, Fuel In Certain Self Contained Cycle and Operating Breathing Apparatus Reactor Licensees 347 CL<
IE Circula r 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 r-
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