ML19316A632

LER 78-006/03L-0:on 780407,reactor Coolant Leak Rate Exceeded 1 Gallon Per Minute,Due to Spray Control Block Valve 2RC-3 Packing & Pressurizer Heater Bundle Leaks.Caused by Blown Packing & Flange Seal Weld Failure

ML19316A632
Person / Time
Site:	Oconee
Issue date:	05/05/1978
From:	Ken Wilson DUKE POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19316A630	List: ML19316A629 ML19316A632
References
LER-78-006-03L-03, LER-78-6-3L-3, NUDOCS 8001130152
Download: ML19316A632 (2)

Text

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P DUKE POER COMPANY OCONEE UNIT 2 Report Number: R0-270/78-6

Report Date: May 5, 1978

! Occurrence Date: April 7, 1978 Facility: Oconee Unit 2, Seneca, South Carolina i Identification of Occurrence: Reactor Coolant Leakage in Excess of I gpm t

Conditions Prior to Occurrence: 100% Full Power Description of Occurrence:

At 1000, on April 6, 1978, it was determined that Cte reacter coolant leakage rate exceeded 1 gpm and an investigation was commenced. By 1500, personnel had entered the Reactor Building (RB) and observed the leak to be from a valve i packing and would require unit shutdown to repair. A safety evaluation pur-suant to Oconce Technical Specification 3.1.6.5 was performed. At 2200 on April 8,1978, the leak was determined to be coming from Spray Control Outlet Block Valve, 2RC-3. This valve and an instrument line root valve were both repacked. On April 12, 1978, the unit was started up but prior to achieving criticality, an additional leak was discovered in the pressurizer heater bundle. This leak was repaired on April 22, 1978. The unit was then returned i to service.

Cause of Occurrence:

The leaks on 2RC-3 and the instrument line root valve were both caused by blown packing. The leak in the pressurizer _ heater bundle was caused by a flange seal weld failure which was evidently initiated during startup af ter i the valve repairs.

Analysis of Occurrence:

1 The leakage rate experience throughout the incident was well within the capa-city of one HP1 pump and no adverse ef fect on Reactor Coolant System capabili-ties resulted. The leakage was entirely contained within the Reactor Building.

' Public health and safety were not endangered by this incident.

A total of 40.885 man-rems of exposure were received by 104 persons involved in the investigation and repair operations.

Corrective Action:

_The two Icaking valves were repacked and the pressurizer heater bundle flange was cleaned and seal welded.

8001130 6 1

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