ML20084M251

Suppl to AO 3-73-3:on 730319,emergency Diesel Generator a Failed to Automatically Start.Caused by Malfunctioned Starting Air Solenoid Valve.Valve Replaced & Defective Valve Subjected to Tests.Valve Spring Assemblies Replaced

ML20084M251
Person / Time
Site:	Turkey Point
Issue date:	02/22/1974
From:	Schmidt W FLORIDA POWER & LIGHT CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084M254	List: ML20084M251 ML20084M255 ML20084M263 ML20084M275
References
AO-3-73-3, NUDOCS 8306020067
Download: ML20084M251 (2)

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Mr. John F. O' Leary, Director 8 1 ,

Directorate of Licensing -

Office of Regulation U. S. Atomic Energy Commission 3W0b%S7Mgy {if  !

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Dear Mr. O' Leary:

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TURKEY POINT UNIT NO. 3 DOCKET NO. 50-250 SUPPLEMENT TO ABNORMAL OCCURRENCE NO. 3-73-3 FAILURE OF THE "A" EMERGENCY DIESEL-GENERATOR TO AUTOMATICALLY START I. INTRODUCTION On March 19, 1973, Abnormal Occurrence Report No. 3-73-3 which concerned the failure of the "A" Emergency Diesel-Generator to automatically start, was submitted in ac-cordance with Section 6.6.2a of the Technical Specifications.

This supplemental report presents the results and ev-aluation of tests and inspections performed to provide assurance that the cause of the failure of the "A" Emergency Diesel-Generator to automatically start was determined and corrected.

II. ADDITIONAL INVESTIGATIVE ACTION As stated in the previous report the starting air solenoid valve was removed and replaced with a spare solenoid valve.

The removed solenoid valve which was suspected of having malfunctioned was subjected to a series of tests in the shop. The tests were designed to check the effect of varying the starting air inlet pressure on the_ operation of the valve. The tests showed that the solenoid valve would fail to close as required when subjected to system air pressures greater than 225 psig. Diesel starting air pressure normally ranges from 225 to 250 psig.

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Page 2 Mr. John F. O' Leary, Director February _ 22, 1974 III. ANALYSIS OF THE OCCURRENCE The starting air solenoid valve admits air pressure.to each of the two starting motor engaging mechanisms causing them to engage the engine flywheel in prepara- >

tion for cranking the diesel. If either of the engaging mechanisms should be slightly misaligned,the starting system is designed to close the starting air solenoid valve and allow the engaging mechanisms to reset and realign. The system will then automatically attempt an-other start of the diesel.

In the incident of March 10, 1973, it has been concluded that one of the starting mechanisms did not engage on the first start attempt and the starting air solenoid. valve did not close when deenergized to allow the engaging mechanisms to reset for the next start attempt. Con-sequently, the subsequent diesel start attempts were unsuccessful.

IV. CORRECTIVE ACTION T0' PREVENT RECURRENCE The spring assemblies of'the starting air solenoid valves for both emergency diesel generators were replaced with sprin Shop'g assemblies testing rated for of a solenoid operation valve in anew with the 250spring psig system.

assembly in a 250 psig air system resulted in 100 suc-cessful operations in 100 attempts. The replacement spring assembly was provided by the valve manufacturer and was consistent with his recommendation.

V. CONCLUSIONS The cause of the incident has been identified and proper corrective action to prevent recurrence of similar in-cidents has been carried out. It is concluded that no further action on this matter is required.

l Very truly yours,

. d Director of Power Resources HNP/knw cc: Mr. Norman C. Moseley, Director Region II Mr. Jack R. Newman

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