05000302/LER-1979-091-03, /03L-0:on 790925,power Range Nuclear Instrument Channel NI-5 Was Erratic Causing Multiple Trip Signals on Reactor Protection Sys Channel A.Caused by Rapid Temp Change from Area Around Instrumentation Detector

/03L-0:on 790925,power Range Nuclear Instrument Channel NI-5 Was Erratic Causing Multiple Trip Signals on Reactor Protection Sys Channel A.Caused by Rapid Temp Change from Area Around Instrumentation Detector

ML19256E010
Person / Time
Site:	Crystal River
Issue date:	10/17/1979
From:	Cooper J FLORIDA POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19256E006	List: 05000302/LER-1979-091, Forwards LER 79-091/03L-0 05000302/LER-1979-091-03, /03L-0:on 790925,power Range Nuclear Instrument Channel NI-5 Was Erratic Causing Multiple Trip Signals on Reactor Protection Sys Channel A.Caused by Rapid Temp Change from Area Around Instrumentation Detector
References
LER-79-091-03L, LER-79-91-3L, NUDOCS 7910250292
Download: ML19256E010 (2)

LER-1979-091, /03L-0:on 790925,power Range Nuclear Instrument Channel NI-5 Was Erratic Causing Multiple Trip Signals on Reactor Protection Sys Channel A.Caused by Rapid Temp Change from Area Around Instrumentation Detector

Event date:
Report date:
3021979091R03 - NRC Website

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This created an event contrary to T.S. 3.3.1.1.

No effect uoQn 1

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SUPPLEMENTARY INFORMATION Report No.:

50-302/79-091/03L-0 Facility:

Crystal River Unit #3 Report Date:

17 October 1979 Occ :r tence Date:

25 September 1979 Identification of Occurrence:

Power Range Nuclear Instrument Channel NI-5 inoperable contrary to Technical Specification 3.3.1.1.

Conditions Prior to Occurrence:

Mode 1 Power Operation (100%)

Description of Occurrence:

At 0515 it was reported that Power Range Nuclear ':nstrument NI-5 lower chamber exhibited erratic fluctuations causing multiple trip signals on reactor protection charnel "A" NI-5 was declared inoperable. Operability was restored following functional testing in accordance with SP-110.

Designation of Apparent Cause:

The apparent cause of the event is attributed to a rapid change in temperature resulting from a loss of area cooling around Nuclear Instrumentation Detector NI-5.

Reference LER 79-090.

Analysis of Occurrence:

No effect upon the plant or general public as redundant protection channels B, C and D were operable.

Corrective Action

Area cooling was returned to normal and NI-5 was returned to service at 1520 following performance of SP-110 Reactor Protection System Functional Test., No.dditional corrective action deemed necessary.

Failure Data:

This is the first occurrence of the tyue reported.

268