ML19316A617

AO-270/75-17:on 750824,component Cooling Sys Activity Increased.Caused by Letdown Cooler a Leak.Letdown Cooler a Removed from Svc & Repairs in Progress.Redundant Cooler Placed in Svc

ML19316A617
Person / Time
Site:	Oconee
Issue date:	09/08/1975
From:	DUKE POWER CO.
To:
Shared Package
ML19316A615	List: ML19316A614 ML19316A617
References
NUDOCS 8001130128
Download: ML19316A617 (2)

Text

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j DUKE POWER COMPANY '

OCONEE UNIT 2 I

Report No.: A0-270/75-17 i

Report Date

_ September 8, 1975 l Occurrence Datet August 24, 1975 ,

1 Facility: Oconec Unit 2, Seneca, South Carolina J

1 Increase in Component Cooling Systec activity Identification of Occurrence:

I Conditions Prior to Occurrence:_ Unit in startup 4

Description of Occurrence:

l On August 24, 1975, the radiation monitor trend recorder for Oconee Unit 2 l

was reviewed to determine trends which might have occurred within the past indicated on process i 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The Component Cooling System count rate, 23, 1975

! monitor 2RIA-50, had increased from 65,000 cpm at 0800, August to 300,000 cpm at 0900, August 24, 1975. A clearly defined step was indicated at about 0930, August 23, 1975, about 20 minutes after a reactor trip from 99 percent full power. A sample of component cooling water was immediately taken and indicated that Fluorine-18 half-life 109.8 minutes was present in addition to the normal background activity.

24, 1975, 1 The "A" letdown cooler was removed from service at 1045, In August order to confirm

) and by 1400 2RIA-50 count rate letdown had decreased slightly.

cooler was placed back in service the source of leakage, the "A" for a short period of time. The count rate immediately increased and the l

l "A" cooler was again taken out of service.

Designation of Apparent Cause of Occurrence:

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The apparent cause of the increased activity in'the Unit 2 Component Cooling .

System is a leak in the "A" letdown cooler.

Analysis of Occurrence:

The letdown coolers are located in the Reactor Building and provide. cooling t

for reactor coolant prior to purification. This incident resulted in an l

approximately 0.2 gal./ min. leak from the Letdown System to the Component l

Cooling System. All radioactivity was contained since the Component Cooling Both the Letdown System and Component Cooling

' System is a closed system. When the leakage System remained capable of performing their design function.

j was discovered, the cooler was isolated and the redundant cooler placed_in

service. It is concluded that the health and safety of the public was not affected by this incident.

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l Corrective Action:

The "A" Ictdown cooler has been taken out of service and isolated and the redundant cooler placed in service. Repairs to the "A" letdown cooler are in progress.

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