05000366/LER-1980-008-03, While Increasing Reactor Power by Rod Withdrawal,Operator Noticed Rod Select Matrix Backlighted & Rod Sequence Control Sys Not Initiating Rod Blocks Properly.Caused by Design Change

While Increasing Reactor Power by Rod Withdrawal,Operator Noticed Rod Select Matrix Backlighted & Rod Sequence Control Sys Not Initiating Rod Blocks Properly.Caused by Design Change

ML19305B960
Person / Time
Site:	Hatch
Issue date:	03/19/1980
From:	Coggin C GEORGIA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19305B958	List: 05000366/LER-1980-008, Forwards LER 80-008/03L-1 05000366/LER-1980-008-03, While Increasing Reactor Power by Rod Withdrawal,Operator Noticed Rod Select Matrix Backlighted & Rod Sequence Control Sys Not Initiating Rod Blocks Properly.Caused by Design Change
References
LER-80-008-03L, LER-80-8-3L, NUDOCS 8003250399
Download: ML19305B960 (1)

LER-1980-008, While Increasing Reactor Power by Rod Withdrawal,Operator Noticed Rod Select Matrix Backlighted & Rod Sequence Control Sys Not Initiating Rod Blocks Properly.Caused by Design Change

Event date:
Report date:
3661980008R03 - NRC Website

text

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LICENSEE EV,ENT REPORT

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3 60 61 COCKET NW9ER 64 6J EVENT DATE 74 7S REPORT DATE 60

' EVENT DESCRIPTIOfJ AND PROBAOLE CONSEQUENCES h o 2 10n 1-29-80. at 1040 CS.T. while increasing reacter oower bv rod wi thd raw-I o 3 la l, the operator noticed the rod select matrix was not backlichted, and i

i 141 Ithe RSCS was not initiatino rod blocks properly.

The RSCS beino inocer-J t

s table is reportable per Tech Specs section 6.9.1.9'.b.

This event is not I

O c lip _plicable to Unit 1.

This is a non-renetitive occurrence.

There were 1

o 7 Ino effects upon public health and safety due to this event.

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4 CAUSE DESCRIPTION AND CORRECTIVE ACTloNS h 1

i O ffhe RSCS did not function oronerly due to a desior, chance which inadver-I 11111 Itently removed the settle cycle inout from the reactor manual control I

Isystem to the group notch control mode of RSCS.

A design change was I

L i 2 lil31lperformed at 1400 CST, 1-29-80, to restore the settle cycle input.

No l

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50-166/1980-008

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Licensto:

Goorgia Power Company Facility Name:

Ed wirn I. Hatch

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Narrative

Report for LER 50-366/1980-008, Rev. 1 On 1-29-80, at 1040 CST with the

reactor, operating at opproximately 150 MWt-in the run mode and while increasing reactor power by control rod withdrawal in rod group 7,

the opera tor noticed that the rod select ma'tr ix was not backlighted, and the rod sequence control system' was not i

initiating rod blocks properly, RSCS was determined to be inoperable, and rod movement was stopped per Tech Specs I

section 3.1.4.2.b.

.RSCS being inoperable is a

condition leading to operation in a

degraded mode permitted by a

i limiting condition for operation, reportable per Tech Specs section 6.9.1.9.b.

This event is not applicabl e to Unit 1.

This is a non-repetitive occurrence.

There were no effects upon public health and safety due to this event.

RSCS did not function properly due to a design change which inadvertently removed the control rod settle cycle input from the reactor manual control system to the group notch control mode of RSCS.

This design change was based on a FDDR which did not soecify the addition of two wires internal to the new O reactor manual control solid state timer.

The omission of the

- internal wires caused the settle cycle input to be removed.

Following the implementation of this d es ign

change, a

functional test was performed to verify o p e ra b i. lit y of RMCS, but since it was performed at greater than 30%

power, it did not show that RSCS was i n o p e ra b l e"..

The test would have been adequate had power been below the RSCS auto byna s s level of 3 0%.

A temporary desi6n change was performed at 1400 CST, r

1 - 2 ", - 8 0,

to restore the system to its on-Eg i na l wiring configuration, allowing the RSCS to perform its intended function.

Operation of RSCS was verified by the backlighting of the rod select huttons and by RSCS in it ia t ing rod blocks properly.

No further corrective action is required.

The original design change will be re-installed, with the addition of the internal wires to the solid state time-,

during the current spring maintenance outage.

This outage is scheduled between March 1,

1980, and April 20, 1980.

The change will be completed during this period.

Functio..al t e s t ing will start during the outage to prove circuitry c on t i nu i. ty,

and RSCS operability will be tested during startup using a

new

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functional test which will properly verify o pe rn b i li t y.

RSCS

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will be tested to verify that rod withdrawa_1 blocks are received following automatte initiation of Group Motch Control Mode of PSCS.

Backlighting w il l.

also be checked during this period to help verify RSCS operability.

The unit is now in i

O full compliance with the requirements for RSCS operability, b U and no further reporting is required.

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