ML20084M947

AO 3-72-1 & 3-72-2:on 720721,during Simulated Conditions, Diesel Generator Bus 3A 4kv Did Not Strip & Bus Voltage 4A 4kv Reduced to Undervoltage Condition,Respectively.Design Changed

ML20084M947
Person / Time
Site:	Turkey Point
Issue date:	07/28/1972
From:	Schmidt A FLORIDA POWER & LIGHT CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084M950	List: ML20084M947 ML20084M980
References
AO-3-72-1, AO-3-72-2, NUDOCS 8306020411
Download: ML20084M947 (2)

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. FLOHiDA iT)NEH & UGHT COMPANY

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Mr. John F. O' Leary l dIdi p[ f Director Directorate of Licensing fja J'

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Dear Mr. O' Leary:

1 Re: Docket No. 50-250 and 50-251 Florida Power & Light Company hereby reports pursuant to the requirements of Section 6.6.2 a(1) of the Technical Specifications two possible abnormal occurrences identified as abnormal occurrences 3-72-1 and 3-72-2.

b Abnormal Occurrence No. 3-72-1 p.

On July 21, 1972, during a simulated safety injection f condition on Unit 3 followed a feu seconds later by a ,O simulated loss of off-site power, the 3A 4KV bus did not \\ l

.gi:1p_., The A diesel generator, which had started automatically upon initiation of the safety injection h

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condition, could not close onto the 3A 4KV bus due to the < [

failure of the bus ,t_o o farip. Investigation of the circuit design and components revealed no problems. The test was repeated several times and operation was correct with normal bus stripping action occurring in each test.

Since there uas no fuel in the reactor, there was no

' nuclear safety hazard involved in this abnormal occurrence. Had fuel been loaded in the core and had an actual safety injection condition occurred with an actual loss of off-site power occurring a few seconds later, sufficient safeguards equipment would have operated from the redundant 3B, 4A and 4B busses to preclude any hazard to the health and safety of the public.

Abnormal Occurrence No. 3-72-2 On July 21, 1972, during a simulated loss of off-site power followed approximately one minute later by a simulated safety injection condition on Unit 3, simultaneous operation of the 4A intake cooling water pump, the 4A component cooling l water pump, the 3A residual heat removal pump, and the 3A and n

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4A safety injection pumps reduced the 4A 4KV bus voltage to an under voltage condition, with subsequent stripping of that bus. The 4B 4KV bus did not reach an under voltage condition with subsequent bus stripping, because the 4B component cooling pump was out of service.

The design was changed so that in the event of a loss of off-site power followed by a safety injection condition the intake cooling water and component cooling water pumps will trip from the non-accident unit. This sequence of events is, of course, highly improbable.

The Plant Nuclear Safety Committee reviewed this design change and recommended that it be implemented and the system be retested. Implementation has been completed and the system tested with satisfactory results.

Since there was no fuel in the reactor, there was no nuclear safety hazard involved in this abnormal occurrence. Had fuel been loaded in the core and had an actual loss of off-site poner occurred followed by an actual safety injection condition approximately one minute later, sufficient safeguards equipment would have operated from the redundant 3A and 3B busses to preclude any hazard to the health and safety of the public.

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A. D. Schmidt Superintendent of Generating Stations ADS:WAF:mn cc: Mr. John Davis Director, Region II Field Otfice D'irectorate of Regulatory Operations Suite 818 230 Peachtree Street, N. ').

Atlanta, Georgia 30303 PTP File

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