05000328/LER-1981-091-03, /03L-0:on 810803,both Train a & B Source Detectors Discovered Disabled.Caused by Lack of Voltage Due to Both Input Error Inhibit Switches Being Placed in Inhibit Position.Switches Returned to Normal

/03L-0:on 810803,both Train a & B Source Detectors Discovered Disabled.Caused by Lack of Voltage Due to Both Input Error Inhibit Switches Being Placed in Inhibit Position.Switches Returned to Normal

ML20010E803
Person / Time
Site:	Sequoyah
Issue date:	08/28/1981
From:	Harding M, Wilkey A TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20010E798	List: 05000328/LER-1981-091, Forwards LER 81-091/03L-0 05000328/LER-1981-091-03, /03L-0:on 810803,both Train a & B Source Detectors Discovered Disabled.Caused by Lack of Voltage Due to Both Input Error Inhibit Switches Being Placed in Inhibit Position.Switches Returned to Normal
References
LER-81-091-03L, LER-81-91-3L, NUDOCS 8109080271
Download: ML20010E803 (2)

LER-1981-091, /03L-0:on 810803,both Train a & B Source Detectors Discovered Disabled.Caused by Lack of Voltage Due to Both Input Error Inhibit Switches Being Placed in Inhibit Position.Switches Returned to Normal

Event date:
Report date:
3281981091R03 - NRC Website

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Sequoyah Nucis2r Plant LER SUPPLEMENTAL INFORMATION SQRO-50-328/81091 Technical Specification Involved:

3.3.1.1 6.9.1.13.b Reported Under Technical Specification :

Date of Occurrence: 08/03/81 Time Of Occurrence: 0640 CDT Identification and Description of Occurrence:

The unit operator observed that both source range detectors were disabled.

Conditions Prior to Occurrence:

Unit in Mode 5 (95' F and 0 PSIG) prior to initial criticality and post-modification testing of SSPS train A in progress.

f pparent Cause of Occurrence:

By placing the input error inhibit switches for both trains in " inhibit",

the voltage to both source range detectors was disabled.

Analysis of Occurr 'ce:

Since the output mode selector switches for both trains were in " test" maintenance personnel were unaware that placing both input error in

" inhibit" would have an effect on the source range detectors.

Corrective Action

The operator immediately notified the instrument mechanic who returned the The source' range input error inhibit switch for train B to " normal".

detectors were therefore immediately returned to service. A procedure change has been initiated.to add a caution to appropriate plant instructions to alert maintenance personnel that this condition will occur.