ML20127G627

RO:720915,emergency Diesel Generator 1 Starting Sys Malfunctioned.Frequency of Maint Schedule for Generator Starting Sys Increased

ML20127G627
Person / Time
Site:	Monticello
Issue date:	10/13/1972
From:	Mayer L NORTHERN STATES POWER CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 9211170395
Download: ML20127G627 (1)

Text

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l rs NSEs e M HERN STATES POWER COMPANY ,

MIN N E A PO LI S. MI N N E S O s

October 13, 1972 @

Mr. A Giambusco d Deputy Director for Reactor Projects pb , 84 4 O

/SgA 7 Directorate of Licensing United States Atomic Energy Commission t Washington, D C 20545 6 i

Dear Mr. Giambusso:

MONTICELIO NUCLEAR GENERATING PIANT Docket No. 50-263 License No. DPR-22 No 12 Bnergency Diesel Generator-No 1 Starting System M11 function A condition occurred at the bbnticello Nuclear Generating Plant which we are re-porting to your office in accordance with Section 6.6.C.1 of the Technical Speci-ficatione, of Provisional Operating License DPR-22.

! On September 15, 1972, during routine surveillance testing, the No 12 DSL START j

FAIIURE alarm was received during a manual start of the No 12 emergency diesel generator. A moment later, the No 12 DSL RUNNING alarm was received indicating that the diesel was running. The local operator verified that the engine had started.

Before disabling the #1 starting system to investigate the malfunction, the engine was successfully started using the redundant f2 starting system. An inspection of the No 12 diesel starting system components revealed rust particles which restricted l the bleed orifice on the No 1 air relay. This resulted in slow opening of the start-l ing motors main air supply valve and the subsequent delayed start. The orifice was cleaned and the engine successfully started by the No 1 starting system. It should be noted that even if the No 1 starting system would have failed completely, the engine would have started, if required, by the automatic selection of the #2 start-ing system.

The air relay bleed orifices for the No 2 starting system on No 12 diesel and both starting systems on No 11 diesel were inspected and found in good condition. 'Ibe l frequency of the maintenance schedule for these items has been increased to a six month basis. No further problem is anticipated.

A Significant Operating Event report will be available at the site for Regulatory Operations Inspector.

Yours very truly, l

L 0 Mayer, P.E.

/

Director of Nuclear Support Services ec: B H Grier IIh 3 S ff

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