ML20127G463
| ML20127G463 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 05/14/1973 |
| From: | Mayer L NORTHERN STATES POWER CO. |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 9211160609 | |
| Download: ML20127G463 (2) | |
Text
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ReNatory Filo Cy.
NORTHERN 5 TATE 5 POWER COMPANY M I N N E A P O n.t S. M I N N E S OT A 8 8 401 May 14, 1973 T)J e m N g.
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Mr J F O'Icary, Director TJ \\ ' "
' N dO Directorate of Licensing o>
United States Atomic Energy Commission 7
Washington, D. C.
20545
Dear Mr O' Leary:
MONTICELLO NUCLEAR GENERATING PLANT Dacket No. 50-263 Licence No. DPR-22 Malfunction of #1 Starting System of #11 Emergency Diesel Generator A condition occurred at the Monticello Nuclear Generating Plant which we are reporting to your office in accordance with Section 6 7.B.l., Abnomal Occurrence Reports, of the hchnical Specifications, of the Provisional Operating License DPR-22.
On May 5,1973, during the Standby Diesel Generator Simulated Automatic Initiation Surveillance test, the #11 Emergency Diesel Generator failed to start on the #1 starting system.
Observation of the #1 starting system indicated that the start-ing motors were not cranking the engine at the proper speed.
The starting systems are designed to crank the engine at 70-80 rpm; however, the No.1 starting system t was only cranking at 50 rpm.
Investigation revealed that the air line lubricator i
in the #1 starting system was inoperative.
This lubricator emits an oil-air mist into the starting system air to provide lubrication for the starting motors.
The inoperability of the air line lubricator resulted in the starting motor receiving insufficient lubrication, thus preventing them from cranking the engine at a sufficient speed for starting.
The #1 starting system air line lubricator was disassembled and blown out with compressed sir. A su.all amount of oil sludge was found in the needle valve port.
The oil was replaced with oil which is specifically designed for use in air motors.
The oil previously used in the lubricators met the recommendations of the manufacturer; however, the replacement oil is expected to provide optimum performance. Following cleaning and replacement of the oil, the lubricator operated properly and the #11 Diesel was successfully started with the #1 starting system.
'Ihe cranking speeG was observed to be within the design specifications.
3245 9211160609 730514 PDR ADOCK 05000263 S
NORT)..4N OTATEC POWER COMPANY Mr J F O'Icary May 14, 1973 The lubricators on the #2 starting system of the No.11 Diesel and both starting systems of the No.12 Diesel vere cleaned, refilled with new oil, and verified to operate properly by cranking the engines.
ib insure that the lubricatore remain in good operating condition they vill be cleaned semi-annually.
This occurrence did not affect safe operation since:
- 1) At the time of the occurrence that plant vac in the cold shutdown condi tion.
- 2) The redundant #12 Diesel was fully operable.
- 3) The #2 starting system van subsequently demonstrated to have been operable and would have started the #11 diesel during an actual automatic initiation.
No previous malfunctions of the air motor lubricators have occurred at Monticello.
Other previous air starting system malfunctions which have occurred at Monticello and other facilities have included plugging, sticking, or other malfunctions of screens, air relays, lubricators, and air motors.
Considering the redundancy of the diesels and air starting systems, the corrective actions (primarily additional or improved preventive ttnintenance) which vere taken for these malfunctionc should result in an extremely low probability for the simultaneous multiple failures which must occur to prevent the diesel generator systems from performing their safety functions. Nevertheless, because of the number of malfunctions which have occurred, a design review is being initiated to consider means of improving the air starting systems.
Very truly yours, W8.
L 0 Mayer, P.E.
Director of Naclear Support Services LOM/ma ec: B H Grier G Charnoff Minnesota Pollution Control Agency Attn: Ken Dzugan
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