ML20084D005

AO 250-74-3:on 740206,engineered Safeguards Sys Energized & Reactor Tripped from Safety Injection Sys Signal.Caused by Improper Engaging of Two Air Driven Starting Motor Pinion Gears W/Engine Flywheel Ring Gear

ML20084D005
Person / Time
Site:	Turkey Point
Issue date:	02/15/1974
From:	Schmidt A FLORIDA POWER & LIGHT CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084D003	List: ML20084D000 ML20084D005
References
AO-250-74-3, NUDOCS 8304080444
Download: ML20084D005 (3)

Text

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FLORIDA POWER & UGHT COVPANY February 15, 1974

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Mr. John F. O' Leary, Director s[h S Directorate of Licensing Office of Regulation q)r g(( p U.S. Atomic Energy Commission Washington, D. C. 20545

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Dear Mr. O' Leary:

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ABNORNML OCCURRENCE NO. 250-74-2" ,(f 3 OV l FEBRUARY 15, 1974 N OCCURRENCE DATE: FEBRUARY 6, 1974 TURKEY POINT UNIT NO. 3 FAILURE OF NO. B EMERGENCY DIESEL GENERATOR TO AUTO START s

A. Condition Prior to Occurrence Unit No. 3 was recovering from a transient load decrease which was caused by the loss of vital instrument bus 3P09.

B. Description of the Occurrence At approximately 2:30 PM on February 6,_1974, Unit No. 3  :

Engineered Safeguards System was energized and the reactor tripped from a safety injection system signal caused by transient operating conditions experienced following the loss of vital instrument bus 3P09. After the reactor tripped, auxiliary power supply was automatically trans-ferred from No. 3 Auxiliary Transformer to No. 3 Startup Transformer. All Engineered Safeguards System equipment started and operated normally except that No. B Emergency Diesel Generator failed to start.

Immediate investigation by plant personnel revealed that

. No. B Emergency Diesel Generator Start Failure Relay in-dicating light was illuminated and the Lockout Relay had actuated. No electrical relay targets were indicated and no engine trip relay indicating lights were illuminated.

Visual inspection of auxiliary systems showed no apparent abnormal conditions.

Immediate operator action was to reset the Lockout Relay and manually start No. B Emergency Diesel Generator. The engine started and reached rated, no-load speed with no further problems.  ! - r 5' 4

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- Mr. John F, O cary Page 2 x-February 15, 1974 C. Cause of the Occurrence Actuation of the Start Failure Relay with no engine trip alarms or electrical relay targets present, indicates ,

that No. B Emergency Diesel Generator failed to attain minimum speed of 200 revolutions per minute within 15 .

seconds.

Evaluation of results of visual inspection of auxiliary systems, the absence of engine trip relay actuation, and the successful manual start of No. B Emergency Diesel Generator concluded that one of the two air driven starting ,

motor pinion gears did not engage properly with the engine flywheel ring gear within 15 seconds. ,

D. Analysis of Occurrence The Engineered Safeguards System was energized as the result of transient operations associated with re-covery from the load reduction caused by the loss of vital instrument bus 3P09. However, once the Engineered }

Safeguards System is actuated, all automatic actions con-tinue until the sequence is completed. Starting both Emergency Diesel Generators is one of the automatic actions initiated when the Engineered Safeguards System is energized.

At the time of this occurrence, there was no loss of W

"d off-site power supply. Therefore the Emergency Diesel Generators were not required for emergency power.

The Safety Analyses presented in the Turkey Point Unit Nos. 3 and 4 Final Safety Analysis Report assume that only one Emergency Diesel Generator operates during the incident analyzed. The capability of one Emergency Diesel Generator to operate all required Engineered Safeguards System equipment was demonstrated during the preoperational test program. No. A Emergency Diesel Generator successfully started and was ready for service, if required. Therefore, the failure of No. B Emergency Diesel Generator to automatically start.did not adversely affect the safe operation of Turkey Point Unit No. 3 and did not present any danger to the public health or safety.

The Start Failure Relay is designed to terminate the engine starting sequence if the Emergency Diesel Gen- ,

erator has not started within 15 seconds. This pro-vides protection against loss of starting air supply, t

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. Mr. John F'~'7' Leary (~/)

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February 15, 1974 v

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, Operator action is required to determine the cause of a r Start Failure, take corrective action, reset the Lockout

"' Relay, and manually start the engine. Termination of

. the engine starting sequence after 15 seconds ensures that a sufficent supply of starting air is availabic to permit manual start of the Emergency Diesel Generator.

"The successful start of No. B Emergency Diesel Generator by the operator, after the initial failure of the engine to automatically start, demonstrated that No. B Energency Diesel Generator could have provided emergency power, if required during this incident.

E. Corrective Action No. B. Emergency Diesel Generator was successfully started using an induced safety injection system signal and demonstrated satisfactory performance.

The components which could result in the failure of No. B Emergency diesel Generator to automatically start were operated through several operating cycles when the engine was manually started and automatically started to demonstrate that No. B Emergency Diesel Gen-erator was operable. Exercising the components associated with the engine starting sequence corrected the immediate problem associated with the failure of No. B Emergency Diesel Generator to automatically start.

,r F. Failure Data Failure of No. A Emergency Diesel Generator to automatically start on two previous occasions were reported as abnormal occurrences. Malfunctions in No. A Emergency Diesel Generator Start System occurred on February 1, 1974 and was discussed in Abnormal Occurrence Report No. 250-74-1.

This is the first failure of No. B Emergency Diesel Generator to automatically start.

-Very truly yours,

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~f D. Schmidt Director of Power Resources VTC:df cc: Mr. Norman C. Moseley, Director Region II Directorate of Regulatory Operation U.S. Atomic Energy Commission Suite 818 230 Peachtree Street, N.W.

Atlanta, Georgia 30303 ,

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