05000353/LER-1990-001, :on 900108,Tech Spec Violation & Reactor Encl Ventilation Isolation Occurred.Caused by Personnel Error. Chief Operator Counseled on Importance of Communicating All Pertinent Info

:on 900108,Tech Spec Violation & Reactor Encl Ventilation Isolation Occurred.Caused by Personnel Error. Chief Operator Counseled on Importance of Communicating All Pertinent Info

ML20006D517
Person / Time
Site:	Limerick
Issue date:	02/07/1990
From:	Madsen G, Mccormick M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-001, LER-90-1, NUDOCS 9002130391
Download: ML20006D517 (7)

LER-1990-001, on 900108,Tech Spec Violation & Reactor Encl Ventilation Isolation Occurred.Caused by Personnel Error. Chief Operator Counseled on Importance of Communicating All Pertinent Info

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(1)
3531990001R00 - NRC Website

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[ 3 f.6 PHILADELPHIA ELECTRfC COMPANY' LIMERICK GENER ATING ST ATION P. O. BOX A t

S AN ATOG A. PENNSYLV ANI A 19464 (rio 27 iroc axv rooo

February 7, 19'90 M. J. McCORMIC K J... P e.

Docket No. 50-353

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License No. NPF-85 U.S. Nuclear Regulatory Commission

' Attn:. Document Control Desk v

Washington, DC 20555

SUBJECT:

Licensee Event Report Limerick Generating Station - Unit 2 This LER reports a condition prohibited by Technical-Specifications in that the Reactor Enclosure (RE) low difterential pressure:- low isolation actuation instrumentation.

- had.been: unavailable to perform its intended safety function for-

' longer than the. Technical Specifications allowed maximum two hour time limit.- In' addition, during restoration of the normal RE ventilation system,1an' isolation of the RE ventilation system, an Engineered Safety-Feature, occurred on low differential pressure.

- Reference:'

Docket Nos. 50-353' Report Number:

2-90-001 Revision: Number:

00 Event:Date:

January 8, 1990 Report Date:

February

.7, 1990

Facility:.

Limerick Generating Station

'P.O.

Box A, Sanatoga, PA 19464 This LER is being submitted pursuant to.the' requirements of 10 CFR 50.73(a)(2)(iv) and 50.73(a)(2)(1)(B).

Very truly yo rs, I

r JKP:aj.

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W. T. Russell, Administrator, Region I, USNRC T. J. Kenny, USNRC Senior Resident Inspector, LGS o

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On January 8, 1990, a condition prohibited-by Technical Specifications (TS) was identified in that the outside atmosphere to Reactor Enclosure (RE) differential pressure-low isolation actuation instrumentation had been unavailable to perform its intended safety function and the associated action had not been taken within the required time period.

Following restoration of E

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.the normal RE ventilation (after completion of scheduled l.

maintenance), an inadvertent isolation of the RE secondary l'

containment and initiation of the Standby Gas Treatment System l

and Reactor Enclosure Recirculation System, both Engiireered Safety Features, occurred due to a low differential pressure isolation logic trip.

The TS violation was caused by a personnel error by Main Control Room Operators when they failed to restore i

l the outside atmosphere to RE differential pressure-low L

instrumentation channels to operable status within the TS required time period.

The isolation of the RE ventilation system was due to the local ' Auto / Test' switches being left in the l

' Test' position rather than the ' Auto' position during RE System l

Shutdown for scheduled maintenance.

The root cause of the 1

l improper local switch position was due to insufficient l-communication between the Chief Operator (CO) and the Shift Supervisor (SSV).

The CO was counseled on the importance of communicating all pertinent information.

In addition, the SSV was counseled on the importance of considering all available information when making decisions.

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Unit' Conditions' Prior to the Event:

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. Operating Condition:

1 (Power Operation)

Power Level.:

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Description of the Event:

On January 8, 1990, at 1914 hours0.0222 days <br />0.532 hours <br />0.00316 weeks <br />7.28277e-4 months <br />, a condition prohibited'by Technical Specifications (TS) was identified.in that the outside atmosphere to Reactor Enclosure (RE) differential pressure-low isolation actuation instrumentation logic had been bypassed

without the' associated TS action being performed within.the required time-period.

Upon identifying this condition, the RE isolation logic was immediately restored.

An inadvertent isolation of the:RE secondary containment and initiation of the Standby Gas-Treatment. System (SGTS)(EIIStBH).and Reactor Enclosure Recirculation System (RERS)(EIIS:AD)., both Engineered

. Safety Features (ESFs), occurred due to the actuation of the low j

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differential-pressure isolation looic.

At 1701 hours0.0197 days <br />0.473 hours <br />0.00281 weeks <br />6.472305e-4 months <br /> on January 8, 1990, the normal Unit 2 RE.

ventilation system was being placed in-service and the

'B' train cof SGTS zwao'being removed from operation after the completion of

' scheduled maintenance on 'B' -RE exhaust fan.

At this time, the Unit:2RE low differential pressure isolation switches'were placed-to ' Reset' to bypass the RE ventilation isolation ~ signal-

- and support restoration of the normal RE-ventilation in accordance with system procedure S76.1.B, "Startup'of Reactor Enclosure HVAC."

With the. switches in ' Reset', bothithe CO and SSV recognized entry into the two hour TS; action statement.

The

'2A' and '2C'JRE ventilation Supply and' Exhaust fans were placed into operation.

These fans were having difficulty maintaining

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adequate RE differential pressure due to known. equipment. problems and therefore the SSV' delayed restoring the ' Reset' switches to prevent inadvertent isolation of RE until the problem of differential pressure oscillations could be evaluated.

The

_ System Engineer for this system adjusted the RE fans such that the differential pressure was stabilized at the negative 0.25 inch waterzgauge by approximately 1845 hours0.0214 days <br />0.513 hours <br />0.00305 weeks <br />7.020225e-4 months <br />.

At 1914 hours0.0222 days <br />0.532 hours <br />0.00316 weeks <br />7.28277e-4 months <br />, the Main Control Room (MCR) SSV realized that the ' Reset' switches had not been returned to the ' Auto' position within the two hour time limit required by TS and immediately directed that the switches be placed to ' Auto' at 1915 hours0.0222 days <br />0.532 hours <br />0.00317 weeks <br />7.286575e-4 months <br />.

Thus, the RE low differential pressure isolation capability was bypassed for y,7a.v.

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approximately 14 minutes in excess of the TS action time limit without completing the action (i.e. SGTS in operation), thereby vio.lating TS LCO 3.3.2.

At 1915 hours0.0222 days <br />0.532 hours <br />0.00317 weeks <br />7.286575e-4 months <br />, when the RE isolation reset switches (HS-76-279A and HS-76-279B) were returned to ' Auto', a RE isolation occurred

- due-to a RE low differential pressure isolation logic trip.

Subsequent investigation into the cause of the isolation revealed that the local ' Auto / Test' switches (HS-76-298A-5 and HS-76-298B-

5) were left in the ' Test' position rather than the ' Auto' o

l position during shutdown of the normal RE ventilation on a previous shift.

The combination of the MCR switches placed in

' Auto' and the local switches in the ' Test' position generated an isolation signal, causing the RE isolation.

Both the

'A' and

'B' trains of SGTS and the A' train of RERS started and operated as designed.

The isolation was reset and normal ventilation was l

restored at 0130 hours0.0015 days <br />0.0361 hours <br />2.149471e-4 weeks <br />4.9465e-5 months <br /> on January 9, 1990.

The RE Secondary L

Containment remained isolated with the SGTS in operation for 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and 15 minutes.

A'four hour notification to the NRC was made on January 8, 1990 l

in accordance with the requirements of 10 CFR 50.72(b)(2)(ii)

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since this event resulted in the automatic actuation of an ESP.

f Accordingly, this report is being submitted in accordance with the requirements of 10 CFR 50.73(a)(2)(iv).

In addition, this report is being submitted in accordance with the. requirements of 10 CFR 50.73 (a)(2)(1)(B) since the action statement'for TS section 3.3.2 had not been met within the required time period.

1 Consequences of the Event:

The consequences of the RE isolation event were minimal in that, l

both the

'A' and

'B' trains of SGTS and the

'A' train of RERS l

initiated as designed to maintain the RE secondary containment

. differential pressure while the normal RE ventilation system had been isolated.

The redundant

'B' train of RERS was available for operation had the

'A' train failed to properly function.

All-systems responded as designed.

There was no release of radioactive material to the environment as a result of this event.

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During the 14 minutes that the TS action was exceeded, a RE low differential pressure condition did not exist.

Had an accident condition occurred, operators would have been alerted via annu'nciation in the MCR and would have responded accordingly.

Had an accident condition occurred, which' generated a RE

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isolation signal other than low differential pressure, SGTS and RERS would have initiated to perform their intended safety function.

Cause of the Event

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The violation of TS Section 3.3.2 resulted from a personnel error by a licensed MCR operator.

Due to the distractions caused by the' differential pressure oscillations in the RE ventilation system, the MCR.SSV failed to adequately track and direct the return of the switches from ' Reset' to ' Auto' within the two hour TS required time period.

The cause of the second event (unexpected isolation of the. Unit 2 g

RE ventilation system when the RE Isolation ' Reset' switches were returned to ' Auto') was due to insufficient communication between the Chief Operator (CO)-and SSV.

The CO failed to provide all pertinent information to the SSV when gaining clarification on which position to leave the local Test. switches following the shutdown of RE ventilation for maintenance.

The switches were originally placed in the ' Test' position during the removal of L

the Unit 2 RE ventilation system from service to support l

maintenance activities at 0443 hours0.00513 days <br />0.123 hours <br />7.324735e-4 weeks <br />1.685615e-4 months <br /> on January 8, 1990.

The RE l

ventilation was isolated in accordance with procedure S76.8.B, i

" Manual' Initiation of Reactor Enclosure or Refueling Floor Secondary Containment Isolation" which stated to " Momentarily place switches to test".

The plant operator who was. performing this function requested clarification from the CO on the meaning of this statement.

The CO asked the SSV about the position of the switches without conveying all pertinent information.

The SSV, utilizing his system knowledge, determined that the switches should be left in the test position.

He failed to review the guidance available in procedure S76.8.B.

Had he reviewed the procedural guidance available, his attention would have been directed towards the word " momentarily".

He may have then questioned how long " momentarily" was, but he would have realized that the switches were not to remain in the ' Test' position for the entire duration of the isolation.

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- cause to this event can be attributed to the use of non-standard terminology in procedure S76.8.B.

The word " momentarily" in,

" momentarily placing switches to Test", does not provide explicit direction to the plant operator performing the actions of the procedure.

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Corrective Actions

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Proper isolation of the RE ventilation system and proper initiation of SGTS and RERS were-verified.

The RE remained isolated until 0130 hours0.0015 days <br />0.0361 hours <br />2.149471e-4 weeks <br />4.9465e-5 months <br /> on January 9, 1990, at which time the remainder of the RE ventilation system maintenance had-been completed and normal ventilation was restored.

i

~ Actions Taken to Prevent Recurrence:

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The SSV, who directed restoration of the ' Reset' switches, was counseled on the importance of properly prioritizing and i

addressing all concerns (i.e. TS time limitations).

In addition, I.

the CO was counseled on the importance of proper communication and the need for transferring accurate and complete information when requesting guidance from the SSV.

The SSV (involved in

- positioning the local ' Test' switches) was counseled on the importance of considering all factors and the available resources i'

when making his decisions.

A shift training bulletin will be issued to all-MCR operators to describe the details'of this event and to emphasize importance of properly tracking TS prescribed time limits for inoperability. --This event 'will be further addressed in an upcoming Licensed Operator Requalification training.

Furthermore, procedure S76.8.B has been revised to include an additional step to direct the restoration of the switches from

. the ' Test' position to their original position after a specified time period (i.e. following the SGTS fan start).

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- aw,- aur,,nn Previous Similar Occurrences:

Other RE Secondary Containment isolation events have been reported; however, only ond event was due to a similar cause.

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Limerick LER l-86-002, reported RE secondary containment isolation due to a handswitch left in the ' Auto' position.

Because the switches in LER l-86-002 were located in the MCR and the switches in this LER are local switches and are operated by different people, the actions to prevent recurrence in LER l 002 would not have been expected to prevent this event.

Tracking Codes:

A07 Failure to properly communicate.

A08 Failure to properly observe changing cond.

A02 Failure to follow implementing procedures.

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