05000346/LER-1978-039-03, /03L-0:on 780417,containment High Radiation Channel 4 Setpoint Out of Tolerance.Caused by Component Failure.Bistable Drifted from Manual Setpoint.Setpoint for Channel 4 Adjusted to Value within Tolerance

/03L-0:on 780417,containment High Radiation Channel 4 Setpoint Out of Tolerance.Caused by Component Failure.Bistable Drifted from Manual Setpoint.Setpoint for Channel 4 Adjusted to Value within Tolerance

ML19326A173
Person / Time
Site:	Davis Besse
Issue date:	05/12/1978
From:	TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19326A170	List: 05000346/LER-1978-039, Forwards LER 78-039/03L-0 05000346/LER-1978-039-03, /03L-0:on 780417,containment High Radiation Channel 4 Setpoint Out of Tolerance.Caused by Component Failure.Bistable Drifted from Manual Setpoint.Setpoint for Channel 4 Adjusted to Value within Tolerance
References
LER-78-039-03L, LER-78-39-3L, NUDOCS 8002030036
Download: ML19326A173 (3)

LER-1978-039, /03L-0:on 780417,containment High Radiation Channel 4 Setpoint Out of Tolerance.Caused by Component Failure.Bistable Drifted from Manual Setpoint.Setpoint for Channel 4 Adjusted to Value within Tolerance

Event date:
Report date:
3461978039R03 - NRC Website

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.Iotal ] SFAS Monthly Test, which was performed on 4/14/78, found that the Contain=ent High l

Io14l l Radiation Trip Bistable for SFAS Channel 4 was out of tolerance.

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l o i s ; l placed the unit in Action Statement 9 of Technical Specification 3.3.2.1.

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1 no dangGT to the health and safety of the public or unit personnel.

Three other SFAS l l o l6 l l O l 7 ] l Containment High Rt.diation Channels were operable during the period that Channel 4 l

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44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS 27 l31ojl The cause of this occurrence was component failure. The bistable had drif ted from l

l3 lij l its manual setpoint. An Instrument and Control technician, in conjunction with an i

I i i 21 1 operator, adjusted the setpoint for SFAS Channel 4 Contain=ent High Radiation to a

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TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION

-~s SUPPLEMENTAI, INFORMATION FOR LER NP-33-78-47 l

DATE OF EVENT: April 17, 1978 FACILITY: " Davis-Besse Unit 1 I_DENTIFICATION OF OCCURRENCE:

Safety Features Actuation System (SFAS) Containment High Radiation Channel 4 setpoint out of tolerance.

Conditions Prior to occurrence:

The unit was in Mode 1, with Power (HRT) = 1838 and Load (MRE) = 606.

l Description of Occurrence: At 1445 hours0.0167 days <br />0.401 hours <br />0.00239 weeks <br />5.498225e-4 months <br /> on April 17, 1978, the designated reviewer of Surveillance Test ST 5031.01, "S7AS Monthly Test", which was per-i formed on April 14, 1978 found that the Contain=ent High Radiation Trip Bistable for SEAS Channel 4 was out of tolerance in the non-conservative direction.

This occurrence placed the unit in Action Statement 9 of Technical Specification 3.3.2.1.

Technical Specification 3.3.2.1 requires that each of four Containment Radiation High Instrument Channels be operable in all modes.

Action Statement 9 states b that power operation may proceed, provided the inoperable unit is placed in the tripped condition within one hour, and three other SFAS Containment Radiation High Instrument Channels are operable.

Designation of Apparent Cause of Occurrence: The cause of this occurrence was component failure. The bistable had drif ted from its manual setpoint. The bi-stable was not immediately adjusted because of personnel error on the part of 1

the operator who performed the Surveillance Test.

The Surveillance Test, ST 5031.01, specifically states that if the trip bistable i's out of tolerance, it is to be declared inoperable and adjusted immediately.

In this case, the 4

operator did not realize that it was out of tolerance, and failed to declare the channel inoperable on April 14, 1978.

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Analvsis of Occurrence: There was no danger to the health and safety of the j

public or unit personnel.

Three other SFAS Containment High Radiatica Channels j

were operable during the period that Channel 4 High Radiation Trip Bistable was inoperable.

The system would have. performed as designed given high radiation levels inside containment.

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DAVIS-BESSE UNIT ONE NUCLEAR F0WER STATION j

SUPPLEMENTAL INFORMATION'FOR LER NP-33-78-47 PAGE 2

Corrective Action

Upon discovery of this occurrence the designated reviewer of Surveillance Test ST 5031.01 immediately notified the Instrument and Control Shop of the situation. An Instrument and Contro1 mechanic, in conjunction with an operator, adjusted the setpoint for SFAS Channel 4 Containment High Radiation to a value within tolerance.

The unit was removed from Action Statement 9.of Technical Specification 3.3.2.1 at 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br /> on April 17, 1978.

The operator who performed ST 5031.01 has been made cognizant of the i=portance of having the channel declared inoperable should the trip bistable setpoint be found out of tolerance.

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6 Failure Data: There have been no previously reportable occurrences involving SFAS Channel inoperability due to setpoint drift.

LER #78-039

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