ML17252A947

Letter Reporting a 10/28/9173 Occurrence at Dresden Unit 3 Relating to the Failure of Diesel Generator Air Starting System

ML17252A947
Person / Time
Site:	Dresden
Issue date:	11/06/1973
From:	Worden W Commonwealth Edison Co
To:	Giambusso A US Atomic Energy Commission (AEC)
References
WPW Ltr. #826-73
Download: ML17252A947 (2)

Text

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WPW Ltr.#826-73 Dresden Nuclear Power Station R. R. #1 Morris, Illinois November 6, 1973 iegulatory Docket .tile 50-249 Mr. A. Giambusso Deputy Director for Reactor Projects Directorate of Licensing U. s. Atomic Energy Conunission Washington, D. C.

• 20545

SUBJECT:

LICENSE DPR-25. DRESDEN NUCLEAR POwER STATION. UNIT #3, SECTION 6.6.B.2 OF THE TECHNICAL SPECIFICATIONS.

FAILURE OF UNIT #3 DIESEL GENERATOR AIR STARTING SYSTEM

Reference:

Notification of Region III of AEC Regulatory Operations Telephone: Mr. F. Maura, 1120 hours0.013 days <br />0.311 hours <br />0.00185 weeks <br />4.2616e-4 months <br /> on October 29, 1973.

Telegram: Mr. J. Keppler, 1140 hours0.0132 days <br />0.317 hours <br />0.00188 weeks <br />4.3377e-4 months <br /> on October 29, 1973.

Dear Mr. Giambussoi This letter is to report a condition relating to the operation of the unit at about 0910 hours0.0105 days <br />0.253 hours <br />0.0015 weeks <br />3.46255e-4 months <br /> on October 28, 1973. At this time, the Unit #3 diesel generator failed- to start when given a start signal from the control room *

. PROBLEM When the deviation occurred, the_* Unit #3 _mode switch was locked in shutdown for inspection of the Bergen-Paterson hydraulic shock*suppressors.

At 0910 hours0.0105 days <br />0.253 hours <br />0.0015 weeks <br />3.46255e-4 months <br /> on*;:.October 28, 1973, the operator gave the Unit #3 diesel generator a start signal from t.he control. room, in preparation for plalllled transformer deluge testing. The diesel generator failed t~ start because sufficient starting air was not inmediately available to rotate the start.ing motors. The shift foreman, who was standing near the diesel generator at the time of the deviation, vibrated the starting air lines and the diesel started and operated satisfactorily. The Unit #2/3 diesel generator was started and loaded to verify its operability.

INVESTIGATION It is believed that the deviation was caused by a small piece of foreign material interfering with the proper operation of the starting air solenoid. When the shift foreman vibrated the starting air lines, the blockage was dislodged and discharged from the system through the starting air motor discharge.

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Mr. A. Giambusso e November 6, 1973 The Instrument-Maintenance Department checked the operation of the starting air high A P alarm and found it to operate satisfactorily.

• The starting motor solenoid was tested several times by the Maintenance Department and operated properly each time. In addition, the Maintenance Department removed, cleaned and replaced the main air valve. The "B" starting air filter, which was in service at the time of the deviation, was taken out of s.ervice and inspected. Inspection of the starting motor solenoid, the main air valve, and the starting air filter revealed nothing which could have caused the deviation.

CORRECTIVE ACTIONS The diesel generator periodic maintenance and inspection procedure was reviewed for adequacy. In light of this review, the procedure was changed to require monthly disassembly, inspection and cleaning of the starting air solenoid.

EVALUATIONS This deviation resulted in no reduction in the margin of safety as defined in the basis for any Technical*.':'.Specification, because the reactor mode switch was locked in shutdown and the Unit 2/3 diesel generator was operable. The safety of the plant and the public was not jeopardized in any way. The operator completed the correct immediate action by verifying operability of the Unit 2/3 diesel generator.

The corrective action previously described should reduce the probability of recurrence of a deviation of this type. The consequences of this deviation have no effect on the startup and subsequent operation of Unit #3.

Sincerely, W. P. Worden Superintendent WPW:do