05000270/LER-1978-006-03, /03L-01: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 Failure

/03L-01: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 Failure

ML19316A636
Person / Time
Site:	Oconee
Issue date:	05/10/1978
From:	Ken Wilson DUKE POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19316A635	List: 05000270/LER-1978-006, Forwards Corrected LER 78-006/03L-01 05000270/LER-1978-006-03, /03L-01: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 Failure
References
LER-78-006-03L, LER-78-6-3L, NUDOCS 8001130158
Download: ML19316A636 (2)

LER-1978-006, /03L-01: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 Failure

Event date:
Report date:
2701978006R03 - NRC Website

text

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O DUKE ItWER COMPANY OCONEE UNIT 2 t

I Report Number:

R0-270/78-6 Report Date:

lby ~10,1978 j

Occurrence Date:

April 7, 1978 Facility:

Oconec Unit 2, Seneca, South Carolina Identification of Occurrence:

Reactor Coolant Leakage in Excess of 1 gpm Conditions Prior to Occurrence:

100% Full Power l

Description of Occurrence:

At 1000, on April 6,1978, it was determined that the reactor coolant leakage l

rate er, eded 1 gpm and an investigation was commenced.

By 1500, personnel had entered the Reactor Building (RB) and observed the Icak to be f rom a valve t

packing and would require unit shutdown to repair.

A safety evaluation pur-suant to Oconee Technical Specification 3.1.6.5 was perf ormed.

At 2200 on April 8,1978, the leak was determined to be coming from Spray Cont rol Outlet Block Valve, 2RC-3.

This valve and an instrument line root valve were both r epacked.

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 l

t o service.

Cause of Occurrence:

The leaks on 2RC-3 and the instrument line root valve were both caused by blown packing.

The Icak in the pressurizer heater bundic was caused by a 1

flange seal failure which was evidently initiated during startup af ter the valve repairs.

Analysis of Occurrence:

The leakage rate experience throughout the incident was well within the capa-city of one HPI pump and no adverse ef fect on Reactor Cociant 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

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in the investigation and repair operations.

Corrective Action

The two leaking valves were repacked and the pressurizer heater bundle flange was cicaned and seal welded.

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ri aecarcan tvcNr CcscnmnCu Ano racs ste ccustcVENCES h [o m [ On April 6,1978, the nC leak rate exceeded 1 gpm.

It was determined that thei t o iH t leak was primarily a packing leak on 2RC-3, the Spray Control Block Valve, I

t o 1 1 1 the valve and an instrument line root valve were repacked.

During startup, l

lo isj tanother leak was discovered in the pressurizer heater bundle.

The weld was la 9jl repaired and the unit returned to service on April 22, 1978.

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t o t il I ef fects resulted since all leakage was contained and no loss of RCS capabilityg ioisiiwas experienced.

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M 33 44 44 a3 43 ee og CAUSE CESC?tiPTION ANo CCA AEC~nVE ACTIONS h t i t o l I The valve leaks were a result of blown oncking.

The pressurizer heater t i t i l I bundle leak was caused by a flange seal failure evidently initiated

]during startup after the valve repairs.

The valves were repacked and the

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e e se K. R. Wilson (704)373-8197 Nwe es entrasta racne:

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