05000281/LER-1981-017-03, /03L-0:on 810210,intermediate Range Channel N36 High Level Trip Setpoint Found in Excess of Tech Spec.Caused by Setpoint Drift.Setpoint Adjusted

/03L-0:on 810210,intermediate Range Channel N36 High Level Trip Setpoint Found in Excess of Tech Spec.Caused by Setpoint Drift.Setpoint Adjusted

ML18139B134
Person / Time
Site:	Surry
Issue date:	03/02/1981
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML18139B131	List: 05000281/LER-1981-005-03, /03L-0:on 810204,air Motors for Preferred Start 2 of Emergency Diesel Generator 3 Found Engaged to Flywheel. Caused by Air Leakage Through Solenoid Valve.Solenoid & Air Motors Replaced 05000281/LER-1981-008-03, /03L-0:on 810206,output Amperage for RM-CC-106 Reduced in Nonconservative Direction.Caused by Failed Remote Indicator Module in Auxiliary Bldg.Module Isolated & RM-CC-106 Recalibr.Monitor Will Be Repaired 05000281/LER-1981-017-03, /03L-0:on 810210,intermediate Range Channel N36 High Level Trip Setpoint Found in Excess of Tech Spec.Caused by Setpoint Drift.Setpoint Adjusted ML18139B130
References
LER-81-017-03L, LER-81-17-3L, NUDOCS 8103060602
Download: ML18139B134 (2)

LER-1981-017, /03L-0:on 810210,intermediate Range Channel N36 High Level Trip Setpoint Found in Excess of Tech Spec.Caused by Setpoint Drift.Setpoint Adjusted

Event date:
Report date:
2811981017R03 - NRC Website

text

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(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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[11] !With the unit at 100% power, during performance of the weekly nulcear instrumetation [I!] I test, PT 1.4, intermediate range channel N36 high level trip setpoint was found at 4

- 4 [IT] 13.6 xxlO-amps, 0.1 x 10-*

in excess of the limit specified by T. S. 2.3.A.l.

This is

';;'""T""cl I reportable* per T. S. 6. 6. 2. b. (1) *

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The redundant intermediate range chaµnel was verified r

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!within the* limit.

The* intermediate range trips are biliocked during power operation, therefore the health and safety of the public were not affected.

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II)) I This failure was caused by drift in the N36 setpoint.

The setpoint was adjusted to TITI IIIl III]

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within the limit~

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ATTACHMENT 1 e

SURRY POWER STATION, UNIT 2

. DOCKET NO:

50-281 REPORT NO:

81-017/03L-0 EVENT DATE:

02-10-81 e

TITLE OF REPORT:

SETPOINT DRIFT ON INSTRUMENTATION FOR REACTOR TRIP

1.

DESCRIPTION OF EVENT

With the unit 100% power, during performance of the weekly nuclear instrumentation test, PT 1.4, int~rmediate range channel N36 was found with a high level trip set-point of 3. 6 x 1071+, amps.

This is contrary to Technical Specification 2. 3. A. l; *. - -

which requires the high setpoint to be less than, equal to the current equivalent to 25% 6£ full power, or 3. 5 x 10... i+ amps.

This _is. reportable per T. S *. 6.. 6.2. b. ( 1).

2.

PROBABLE CONSEQUENCES AND STATUS OF REDUNDANT SYSTEMS:

The redundant intermediate range channel was operable and the setpoint was verified within the limit by the same periodic test.

The intermediate range channels are not required for core protection during power operation, and are blocked above 10%

.,)..

power and in addition, are tested weekly; therefore the health and safety of the public were not affected.

3°.

CAUSE

The high setpoint was caused by electronic drift in the intermediate range (N36) channel *

. *. 4.

IMMEDIATE CORRECTIVE ACTION

The setpoint was adjusted to within the limit:

5.

SUBSEQUENT CORRECTIVE.ACTION:

None required.

6.

ACTIONS TAKEN'TOPREVENT RECURRENCE:

No further action is required.

The Periodic Testing-Ero gram-is-designed-to-locate---------

this type of.failure.

7.

GENERIC IMPLICATIONS:

None.