ML19274E781

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LER 79-031/01T-0 on 790412:during Routine Radwaste Release, Release Monitor Went Into High Alarm Because Radwaste Isolation Valves WDV-320 & 321 Failed to Close.Caused by Sticking Contacts in Monitor Bypass Switch
ML19274E781
Person / Time
Site: Crystal River Duke Energy icon.png
Issue date: 04/17/1979
From: Cooper J
FLORIDA POWER CORP.
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19274E778 List:
References
LER-79-031-01T, LER-79-31-1T, NUDOCS 7904240403
Download: ML19274E781 (2)


Text

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790424 0qD3 ( E ATTACHED SUPPLEMENTARY DIFORMATION SHEET)

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SUPPLEMENTARY INFORMATION Report No.. 50-302/79-031/0lT-0 Facility: Crystal River Unit #3 Report Date: 17 April 1979 Occurrence Date: 12 April 1979 Identification of Occurrence:

Automatic closure of radioactive liquid waste isolation valves did not occur contrary to Environmental Technical Specification 2.4.1.D.

Conditions Prior to Occurrence:

Mode 1 power operation (73%)

Description of Occurrence:

At 1000, whila making a routine liquid radiation waste release, the liquid radiatiot release monitor (RML-2) went into high alarm. An immediate check to assure interlock actuation revealed that the liquid radiation waste isolation valves WDV-320 and WDV-321 failed to close. Actuation of the bypass switch several times terminated the release at 1001 with the closure of WDV-320 and 321.

Designation of Apparent Cause:

The apparent cause of this event has been attributed to several contacts sticking within the radiation monitor by-pass switch.

It has been determined that the contacts remained engaged without indication following the completion of Surveillance Procedure SP-335, Radiation Monitoring Functional Test.

Analysis of Occurrence:

There was no hazard to the plant or general public as the one minute release did not exceed the values specified in 10 CFR 20, Appendix 3, Table II, Column 2, for unrestricted areas. The cal-culated release rate at the point of discharge was 3.2 E-4 MPC's as determined from a 30 gpm release rate. The quantity of activity released following the high alarm is estimated to be 16 pCi.

Corrective Action:

The radiation monitor by-pass switch contacts were cleaned and lubricated. Functional checks were performed to verify proper switch / interlock operability. No recurrence on subsequent releases.

Failure Data:

First occurrence of an event of this type reporten.

/rc