ML19317F458

RO 270/76-01:on 760122,unidentified Reactor Coolant Leakage Exceeded 1 Gallon Per Minute.Caused by Root Valve Leak to Pressurizer Level Transmitter LT-1.Transmitter Isolated & Valve Closed

ML19317F458
Person / Time
Site:	Oconee
Issue date:	01/22/1976
From:	DUKE POWER CO.
To:
Shared Package
ML19317F450	List: ML19317F449 ML19317F458
References
RO-270-76-01, RO-270-76-1, NUDOCS 8001140692
Download: ML19317F458 (2)

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% s DUKE ~ POWER COMPANY OCONEE UNIT 2 Report'No.: R0-270/76-1

' Report Date: January 22, 1976 Occurrenca Date: January 10, 1976' Facility: Oconee Unit 2, Seneca, South Carolina

, Identification of Occurrence: Unidentified reactor coolant leakage exceeding 1 gpm.

Conditions Prior to Occurrence: Unit at 100% full power.

Description of Occt;rence:

On January 10,1976, surveillance testing was performed to determine the Reactor Coolant System leakage for Oconee Unit 2. A system leakage greater than 1 gpm, the maximum unidentified reactor coolant leakage as stated in Oconee Technical Specification 3.1.6.2, was detected. Within approximately 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />,.the leakage was determined to be in an area of the Reactor Building which is inaccessible during reactor operation. A reactor shutdown was begun to facilitate inspection in these areas. Further investigation traced the leakage to an upper instrument root valve to pressurizer level

. transmitter UI-1. Within a total. elapsed time of 19 hours2.199074e-4 days <br />0.00528 hours <br />3.141534e-5 weeks <br />7.2295e-6 months <br /> following the initial determination of leakage, reactor shutdown was completed, and coolant leakage was reduced to allowable limits by isolating the pressurizer level transmitter and closing the root valve.

Apparent Cause of Occurrence:

This incident was apparently caused by a packing leak on an upper instrument root-valve to-pressurizer level transmitter Ur-1.

Analysis of Event:

Estimated leakage during-this incident was approximately 3 gpm. The leakage was contained inside the Reactor Building and did not present a problem in respect to in-plant radioactivity and contamination. The amount aof Icakage was well within the capacity of the Radioactive Waste Treatment System to handle, and the amount of make-up necessary to the primary system was well within the capacity of the High Pressure Injection System. Also,

- the leakage did not exist through a non-isolable fault in a reactor coolant strength boundary. It is concluded that the health and safety of the public was not affected by this incident.

8001140SM

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.RO-270/76-1.

January =21,11976

-Page-2 Corrective'Ac_ tion:

Pressurizer level transmitter _LT-1:was isolated, and.the Icaking roct valve was closed:to stop the. leakage. The valve packing will be repaired during a subsequent reactor outage.- In the meantine, pressurizer 1cvel will be

- monitored during operation by two additional-back-up pressurizer Icvel transmitters.

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