ML19354D662

LER 89-035-00:on 891129,during Channel Functional Test of ECCS Drywell Pressure Channel,Operator Selected Wrong Channel for Testing,Causing Isolation of Instrument Air Sys. Caused by Personnel Error.Briefing conducted.W/891221 Ltr

ML19354D662
Person / Time
Site:	Clinton
Issue date:	12/21/1989
From:	Holtzscher D, Morris D ILLINOIS POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-035, LER-89-35, U-601575, NUDOCS 8912290023
Download: ML19354D662 (5)

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L45 89(12- 21) LP 20.220 ILLIN018 POWER 00MPANY CLINTON POWER STATION. P.O. box 678. CLINTON ILLINOIS 61727 December 21, 1989 10CFR50.73 Docket No. 50 461 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 Sub,iect : Clinton Power Station - Unit 1 Licensee Eveit Reng l yo. 89 0]idtQ

Dear Sir:

Please find enclosed Licensee Event Report No. 89 035 00:

Familiarity with Task Results in Selection of Wrong Channel During Drywell Pressure Channel Functional Test and Isolation of Instrument Air System. This report is being submitted in accordance with the requirements of 10CFR50.73.

Sincerely yours, M

D. L. Holtzscher Acting Manager -

Licensing and Safety RSF/krm Enclosure cc: NRC Resident Office NRC Region III, Regional Administrator INPO Records Center Illinois Department of Nuclear Safety NRC Clinton Licensing Project Manager f1

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''' Familiarity with Task Results in Selection of L'rong Chantiel During Drywell Pr ssure Channel Functional Test and Isolation of Instrument Air System.

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ro .a i.m uo so n w an.m oo.nmQno LICth$tt CONT ACT POR THIS Lt A till NAMt 'IttP' ONE H NUMDE R 68tta 0004 D. R. Morris, Director-Plant operations, extension 3205 21117 913151-I8I8I811 COMPLtti ONE r INE FOR F ACM COMPONINT f AltURE CFSChitt0 IN ?Mit AEPont tisi Caust 8vlttw COMPONENT

""% "C' Too agtA Caust sysit w CovPONINT va%AC ]Pontag t I l I l I l l l I i i _ 1 I i 1 l I l l l l 1 1 I I l l 1 SUPPttMENT AL mtP0mf ERPtrit0 H.i MON 1 H Day vtan SutwitsiON tt 5 til yes, eeenonene ikPEC1tO $v96tt$$lON DA Til NO l l l AS$T#ACT itsmst to fuu speces # e . escapaveerese erseen v osve apsre typeweersea maest etti On November 29, 1989, an operator was performing a channel functional test (CFT) of Emergency Core Cooling System drywell pressure channel 1B21 N694E. During the CFT, the operator selected the wrong channel for testing, 1B21 N691E and, as required by the CPT procedure, placed that channel in the calibration mode. Placing 1B21 N691E in the calibration mode caused the channel to trip. The operator immediately recognized his error when the indicator light for channel 1B21 N691E illuminated. The trip of 1821 N691E initiated a reactor vessel water low level trip signal which caused the containment and drywell isolation valves of the Instrument Air system (IA) to close. Operators did not recognize the IA isolation until the scram pilot valve air header pressure low annunciator initiated. The cause of this event is attributed to operator error due to familiarity with the task. The method used to perform the CPT is repetitive. Corrective action for this event includes briefing Operations shift crews on this event, using unique markings and an

" operator aid" to enhance operator recognition of certain channels, investigating the feasibility of preventing a trip signal from being present when a channel is selected, investigating the modification of analog trip software, and developing training on "self checking".

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0l0 0l2 0F 0 l4 i isxt u . < w unc u . ass m on DESCRIPTION OF EVENT On November 29, 1989, the plant was in Mode 1 (POWER OPERATION), at approximately sixty five percent reactor (RCT) power. At 1903 hours0.022 days <br />0.529 hours <br />0.00315 weeks <br />7.240915e-4 months <br />,  !

Instrument Air (IA) system [LD) containment and drywell isolation valves

[ISV) 11A005 and 11A008 automatically closed because of a reactor vessel water low level (level 1) trip signal.

On November 29, 1989, at 1845 hours0.0214 days <br />0.513 hours <br />0.00305 weeks <br />7.020225e-4 months <br />, a utility licensed operator began -

channel functional surveillance test 9030.010008, " Emergency Core Cooling System (ECCS) Drywell Pressure B21 N694A (E, B, F) Channel Functional checklist," for analog trip module (ATM) channel 1B21 N694E, drywell pressure. Surveillance test 9030.010008 is performed, in part, by selecting the ATM channel to be tested and then placing the ATM channel >

in the calibration mode. Placing ATM channel 1B21 N694E in the calibration mode causes a calibration mode indicator light [IL) to illuminate. Depending on certain conditions, placing an ATM channel inte the calibration mode may cause the ATM to trip. When an ATM is selected and placed in the calibration mode, a test signal is automatically applied to the ATM. The magnitude of the test signal will normally be equal to the value last used to test the ATM. If the magnitude of that test signal exceeds the trip setpoint of the ATM, then the ATM will trip.

At 1903 hours0.022 days <br />0.529 hours <br />0.00315 weeks <br />7.240915e-4 months <br />, the operator performing surveillance test 9030.010008 on ATM channel 1B21 N694E inadvertently selected the wrong ATM channel, reactor water level channel 1B21-N691E, and placed that channel in the calibration mode. Placing ATM channel 1B21-N691E in the calibration mode caused illumination of the calibration mode indicator light associated with this ATM channel and initiation of the reactor vessel water low level annunciator [ ANN). When the indicator light illuminated, the operator immediately recognized that he had selected the wrong ATM channel for the surveillance test.

The operator restored ATM channel 1B21 N691E to its normal status within fourteen seconds of selecting the wrong channel for testing. Following this restoration, the operator notified the "A" area operator that the wrong ATM channel had been selected for the surveillance and then proceeded with the surveillance test on the correct ATM channel, channel 1B21 N694E.

Inadvertently placing ATi. channel 1B21-N691E into the calibration mode caused the ATM to trip. The trip of this ATM caused a reactor vessel water low level (level 1) trip signal and resulted in the automatic closure of IA system containment and drywell isolation valves 11A005 and IIA 008. The actuation logic for the IA system isolation valves is one-out of two from a reactor vessel water low level (level 1) trip signal.

Operators did not immediately recognize that these valves had closed (there is no annunciator for the IA system isolation).

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010 0 l3 0F 0 14 rnus um. u.~ a mome. n eenaww ec rom, nsaw sm At approximately 1910 hours0.0221 days <br />0.531 hours <br />0.00316 weeks <br />7.26755e-4 months <br />, the Scram Pilot Valve Air Header Pressure Low annunciator automatically initiated. This annunciation alerted control room operators (CR0s) that the containment and drywell isolation valves for the IA system had closed. The CR0s reset the isolation trip logic and opened valves 11A005 and 11A008.

Operators performed off normal procedure 4001.020001, " Automatic Isolation Checklist," to verify that the correct equipment actuations had occurred in response to the reactor vessel water low level (level 1) trip signal. Performance of procedure 4001.020001 verified that the appropriate valves, 11A005 and 11A008, closed as designed in response to the reactor vessel water low level (level 1) trip signal.

The closure of the instrument air valves causes air pressure to the scram pilot valve air header to decay and eventually results in the opening of the control rod scram valves [V) and drifting of control rods into the reactor core. Therefore, operators verified that no control rod movement had occurred while the IA isolation valves were closed.

No automatic or manually initiated safety system responses were necessary I to place the plant in a safe and stable condition. No other equipment or components were inoperable at the start of this event such that their inoperable condition contributed to this event.

CAUSE OF EVENT The cause of this event is attributed to personnel error by a utility licensed operator. The operator inadvertently selected the wrong ATM channel for the surveillance because of being too familiar with the task.

The method used in performing the channel functional test of ATM channels is repetitive and similar to the method used to perform channel check surveillances.of ATM channels on a once per shift frequency.

The operator's error was compounded by the presence of the trip signal in the ATM channel when the ATM channel was selected and placed in the calibration mode. (The presence of a trip signal is within the design allowance.)

CORRECTIVE ACTION The operator who caused this event quickly recognized his error in selecting the wrong channel for surveillance; therefore, no specific corrective action was necessary with respect to this specific operator, however, Operations shift crews were briefed on this event at their pre-shif t briefings.

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010 0l4 0F 0 l4 I text v a m.= w. w me i asu v nn j IP will apply unique markings on ATM cards to identify ATM channels that have single channel trip logics. These markings are scheduled to be applied by March 15, 1990. .\dditionally, IP will post an " operator aid" that lists the ATM channels that have single channel trip logics. The

" operator aid" is scheduled to be posted near the key pad used in testing ATM channels by January 31, 1990. These actions may enhance operator recognition of channels which alone can cause system actuations. .

IP will investigate the feasibility of preventing a trip signal from being present in ATM channels that have single channel trip logic when an ATM channel is selected and placed in the calibration mode. This investigation is scheduled to be completed by January 31, 1990.

IP will investigate modifying the Analog Trip Software for ATMs with single channel trip logic to provide an operator flag which will require two deliberate operator actions to place the ATM into the calibration mode. This investigation is scheduled to be complete by March 15, 1990.

To reduce personnel errors that occur as a result of performing familiar tasks Illinois Power Company (IP) will develop training on "self checking". Development of this training is scheduled to be completed by February 15, 1990. Following development of the training, appropriate Clinton Power Station personnel will be trained on "self checking".

ANALYSIS OF EVENT This event is reportable under the provisions of 10CFR50.73(a)(2)(iv) because of the automatic actuation of an engineered safety feature, containment and drywell isolation valves 11A005 and 11A008.

Assessment of.the safety consequences and implications of this event indicates that the event was not nuclear safety significant for existing plant conditions or other plant modes or power levels, Events resulting from the loss of the instrument air system have been analyzed in Chapter 15 of the Updated Safety Analysis Report. The analysis determined that l

the transients resulting from the loss of the instrument air system are

within the limits of the plant design.

ADDITIONAL INFORMATION No components failed during this event.

No other reportable instrument air system isolations have occurred as a result of a similar cause.

For further information regarding this event, please contact D. R.

Morris, Director - Plant Operations, at (217) 935 8881, extension 3205.

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