ML20044A641

LER 90-011-00:on 900601,full Reactor Protection Sys Actuation Occurred When Mode Switch Moved to Run Position, Resulting in Scram Signal on MSIVs Less than 90% Open.Caused by Personnel Error.Individual counseled.W/900622 Ltr

ML20044A641
Person / Time
Site:	Hatch
Issue date:	06/22/1990
From:	Hairston W, Tipps S GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HL-1162, LER-90-011-01, LER-90-11-1, NUDOCS 9007020003
Download: ML20044A641 (6)

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June 22, 1990 1 1

U.S. Nuclear Regulatory Commission j ATTN: Document Control Desk

. Washington, D.C. 20555 PLANT HATCH - UNIT 1 J

NRC DOCKET 50-321 OPERATING LICENSE DPR-57  !

l LICENSEE EVENT REPORT l l PERSONNEL ERROR RESULTS IN A j l

REACTOR PROTECTION SYSTEM ACTUATION Gentlemen. ,

1 In accordance with the requirements of 10 CFR 50.73(a)(2)(iv), Georgia I Power Company is submitting the enclosed Licensee Event Report (LER) )

-concerning a reactor protection system actuation due to personnel error, j

.This event occurred at Plant Hatch - Unit 1.

Sincerely, I b/~

W. G. Hairston, Ill  ;

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Enclosure:

LER-50-321/1990-011 ..

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U.S. Nuclear Regulatory Commission June 22, 1990 Page Two  ;

c: Georaia Power comoany Mr. H. C. Nix, General Manager - Nuclear Plant >

Mr. J. D. Heidt, Manager Engineering and Licensing - Hatch l GO-NORMS U.S. Nuclear Reaulatory Commission. Washinaton. doc 1 -

Mr. L. P. Crocker, Licensing Project Manager - Hat.ch U.S. Nuclear Reculatory Commission. Reaion II  :

Mr. S. D. Ebneter, Regional Administrator Senior Resident inspector - Hatch ,

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On 6/1/90 at approximately 1549 CDT, Unit 1 was in the Startup mode with all control rods' fully inserted and the Main Steamline Isolation Valves (MSIVs) closed. At that time, a full Reactor Protection System (RPS) actuation occurred when the mode switch was moved inadvertently to the Run position resulting in the generation of a scram signal on MSIVs less than 90?P open while in the Run mode. The mode switch was moved inadvertently too far to the Run position by a licensed plant operator as he was adjusting it in an attempt to clear the " Rod Sequence Control System Malfunction" annunciator. The scram, which caused no rod movement because all rods were already fully inserted, was reset at approximately 1550 COT. The annunciator was cleared when a failed sequence logic board in the Rod Sequence Control System was replaced.

'The cause of this event is personnel error by a licensed plant operator. The operator, in an attempt to clear an annunciator, adjusted the mode switch to ensure all position dependent contacts on the mode switch were in their proper position. He erroneously thought the annunciator might have resulted from some of the position dependent contacts not being in their proper position.

Corrective actions for this event include counseling the operator and covering this event in the Operational Experience Assessment Report issued monthly to all licensed personnel.

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PLANT AND SYSTEM IDENTIFICATION General Electric - Boiling Water Reactor Energy _ industry Identification System codes are identified in the text as (Ells Code XX).-

SUMMARY

OF EVENT.

On 6/1/90 at approximately 1549 CDT, Unit 1 was in the Startup mode with all control-rods fully inserted and the Main Ste mline Isolatiqn Valves (MSIVs EIIS Code JM) iclosed. At that time, a full Reactor Protection System (RPS, Ells Code JC)

' actuation occurred when.the mode switch was moved inadvertently too far to the.Run

[ = position resulting in the geMration of a scram signal on MSIVs less than 90% open while in the Run mode. The mode switch was moved to the Run position by a licensed

plant operator as he was adjusting it in an attempt to clear the " Rod Sequence

' Control System Malfunction" annunciator. The scram, which caused no rod movement

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= because all rods _ were already fully inserted, was reset at approximately 1550 COT.

The annunciator _was: cleared when a failed sequence logic board in the Rod Sequence Control System was-replaced.

The cause of this event is personnel error by a licensed plant. operator. Me operator, in' an = attempt to clear an annunciator, adjusted the mode switch to ensure

.all position dependent contacts on the mode switch were in their proper position.

It was erroneously thought the annunciator might have resulted from some of-the potition dependent contacts not being in their proper position.

Corrective actions for this event include counseling the operator and covering this f event in the Operational Experience Assessment Report issued monthly to all licensed personnel.

b DESCRI[fl0N OF EVENT h- - 0'n_6/N90 at approximately 1517 CDT, the Unit i reactor mode svitch was placed f rom the Refuel position to the Startup position as part of unit startup cctivities from a'a.dintenance/ refueling outage. The MSIVs had been closed previously (at

, approxiniately 1235 COT) to support turbine (Ells Code TA) testing activities. After placing the mode switch in the startup position and prior to beginning control rod-

.withd'awal, annunciator " Rod Sequence Control System Malfunction was received on

alarm panel 1Hll-P603-2 in the Main Control Room. This annunciator indicates'a malfunction in the RSCS rod withdrawal control logic and is armed when the mode switch is not in the Refuel position.

Licensed Operations _ personnel thought the annunciator might have been due to some of the mode switch's position dependent contacts not beiriv in their proper

-- position. The operator attempted to clear the annunciator by a(iusting the mode switch to get the posicion dependent contacts to go to their proper position. In

, adjusting the mode switch, the operator moved it too far, placing it in the Run position.

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010 013 0 14 TEXT l# more mece a esewei ese ecpeans/ NRC Fonn 3lEA'st 1171 The operator's inadvertently placing the inode switch in the Run position resulted in a full RPS actuation on MSIVs less than 90% open while in the Run mode. This occurred at approximately 1549 CDT with both the " A" and the "B" trip systems in the RPS actuating per design. No control rods moved because they were already f ully inserted. %e RPS was reset at approximately 1550 CDI.

Plant Instrument and Controls personnel investigatea to determine the actual cause for the RSCS malfunction annunciatar. They found a failed logic sequence card in thc RSCS control rod selection logic. The f ailed card would have allowed control rods in the A group and the B group of the RSCS to b? selected simultaneously. This defeats the design purpose of the RSCS. Theref ore, the logic is set-up to annu'nciate this malfunction and the associated annunciator response procedure is written to require the Rod Select Power switch to be Dlaced to "off' to prevent control rod movement. The f ailed card was replaced, the RSCS was proven operable, and control rod withdrawal was begun at approximately 1722 CDT.

CAUSE OF THE EVENT 1he cause of this event if personnel error by licensed plant Operations personnel. An operator, in an attempt te clear an annunciator, adjusted the mode switch. He did this to ensure all position dependent contacts on the mode switch were in their proper position. it was erroneously thought the annunciator might have resulted from some of the position dependent contacts not being in their proper position. In adjusting the mode switch, he inadvertently moved it too far, placing it in the Run mode and generating an RPS actuation (scram) signal.

REPORTABILITY ANALYSIS AND SAFETY ASSESSMENT This report is required per 10 CFR 50.73(a)(2)(iv) because this event resulted in an unplanned RPS actuation. Specifically, a full RPS actuation (scram) occurred when the mode switch was inadvertently moved to the Run position while the MSIVs were closed.

This resulted in the generation of a scram signal on MSIVs less than 90% ope while in the Run mode.

The RPS automatically initiates a reactor scram to ensure the radioactive materials barriers (such as the f uel cladding aN pressure systcm boundary) are maintained and to mitigate the consequences of transients and accidents. The MSIVs have position switches installed on the valves which provide trip signals to the RPS. If the MSIVs were to close suddenly, this could cause a rapid pressure increase in the reactor vessel. The pressure increase could a @ ersely affect the reactor vessel and would result in a positive reactivity insertion doe to void collapse. The MSIV closure scram anticipates the neutron flux and high pressure ; crams in order to provide additional safety margin.

In this event, an MSIV closure scram signal was generated when the mode switch was inadvertently moved to the Run position, arming the scram logic f or this signal, when the MSIVs were s.losed. Both trip systems of the RPS tripped per design No control rods actually moved because all rods were inserted fully. Had an actual condition existed which required a scram from power operation, the RPS would have functior'd per design to insert the control rods and protect the radioactise materials barriers.

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- safety. _This analysis is applicable to all power levels.

a CORRECTIVE ACTIONE l.

The involved individual has been made aware of his mistake and the need to anticipate s - the potential adverse consequences of his actions. Additionally, this event will be-

--included in the Operationat Experience Assessment Report issued monthly to all licensed personnel. In~this way, all licensed personnel will be informed of the relationship between'the RSCS malfunction alarm and the mode switch position and the potential consequences associated with adjusting the mode switch. This action will be completed by 7/31/90.

ADDITIONAL INFORMATION

1. Previous Similar Events:

There were two previous similar evants in which a scram signal was received with o the unit shutdown and all rods fully inserted. They were reported in LER 50-321/1988-02 dated 5/6/88 and LER 50-366/1989-009 dated 12/27/89. In the first L event, a false low level signal was generated during instrument reference leg _-

[ backfilling activities resulting in an RPS actuation on low reactor water level.

r in the _second event, an actual Scram Discharge Voluna (SOV) high level condition

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resulted when a loss of' air allowed the scram valves to drif t open resulting in a F discharge'of reactor water to.the SDV. The SOV high level caused an RPS actuation.

Corrective actions for those two events would n"t have prevented the event

> described in this report because the causes of the three events were different.

The first event was caused by Instrument and Controls technician personnel error.

The second event was caused by component failure leading to a loss of the in-service air compressor and subsequent loss of air. These causes and their associated corrective actions were unrelated to the cause of this event.

2. . Faileft Component Identification:

ik Master Parts List Number: None Manufacturer: General Electric Root Cause Code: X Podel Number: 19589486AAG001 Ells Component Code: CBD

- Type: Sequence Logic Board Manufacturer Code: G080 Ells System Code: None Reportable to NPRDS: No

3. Other Affected Equipment:

No systems other than RPS were affected by this event.

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