ML20028G918

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LER 90-020-00:on 900831,maint Activities on Control Room Emergency Recirculation Sys Resulted in Tech Spec Violation & Compromise of Safety Sys.Caused by Program Deficiency. Maint Acitivities & Insp Being revised.W/900928 Ltr
ML20028G918
Person / Time
Site: Perry FirstEnergy icon.png
Issue date: 09/28/1990
From: Hegrat H, Lyster M
CENTERIOR ENERGY
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-020, LER-90-20, PY-CEI-NRR-1232, NUDOCS 9010030232
Download: ML20028G918 (5)
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PERRY NUCLEAR POWER PLANT Mail Address:

10 CENTER ROAD P O. BOX 97 Michael D. Lyster PERRY. OHIO 44081 PERRY. OHIO 44081 Vice President Nuclear (216)259 3737 -

September 28, 1990 ,

PY-CEI/NRR-12n L i

U.S. Nuclear-Regulatory Commission l Document Control Desk l Washington, D.C. 20555 Perry Nuclear Power Plant Docket No. 50-440 LER 90-020

Dear Sir:

Enclosed ir, Licensee Event Report 90-020 for the Perry Nuclear Power Plant.

Sincer y j

Michael D. L ster

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Enclosure:

.LER 90-020 ,

4 cc NRR Project Managet-Sr. Resident. Inspector i

U.S. Nuclear Regulatory Commission  !

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in Technical Specification Violation and Compromise of a Safety System.

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' M i i l l l l 1 l l I I I I I SUPPL $tW8Ef AL REP 0ft? taPECT90 (14) amostTM DAY vtAA SUSMi& BION l itE let v tern.0neen GRPLCTRO SUOeilS$toer Daitt NO l l l l AseT Act m , J.= , . . , 0 . 0 , nei l On August 31, 1990, at approximately 1430, maintenance activities on a Control l Room Heating, Ventilation, and Air Cond'.tioning (CRRVAC) system backdraf t ' damper caused the inoperability of both trains of the Emergency Recirculation mode of the CRHVAC system which resulted in a violation of Technical Specification 3.7.2 and in a condition that alone could have prevented the fulfillment of the safety

function of a system that is needed to mitigate the consequences of an accident.

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l The cause of this event is program deficiency. The maintenance activities that l were being performed on the common plenum were not identified as causing'both l trains of the Emergency Recirculation mode of CRHVAC to be inoperable. Due to inadequate consideration of the implications of the design and construction of l the CRHVAC system common plenum, maintenance activities which required opening '

l access covers that compromised the Control Rcom envelope were accomplished'during plant operating conditions when the actiou statemetic for Technical Specification 3.7.2 required entry into Technical Specification 3.0.3.

To prevent recurrence, maintenance activities and inspections are being revised or rescheduled to preclude violation of the control envelope during applicable plant operating conditions. Engineering is investigating means to improve reliability / testability / maintainability of CRHVAC backdraft dampers.

Investigation into a modification of the Technical Specification 3.7.2 Action Statements to allow system operation with a common plenum access cover removed under specific conditions is also in progress.

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1 On August 31, 1990, at approximately 1430, maintenance activities on a Control Room Heating, Ventilation, and Air Conditioning [VI] (CRHVAC) system backdraf t '

damper [UDMP] caused the inoperability of both trains of the Emergency Recirculation mode of the CRHVAC system, which resulted in a violation of

,r Technical Specification 3.7.2 and in a condition that alone could have prevented a the fulfillment of the safety function of a system that is needed to mitigate the

  • 4 consequences of an accident. At the time of the event, the plant was in Operational Condition 1 (Power Operation) at approximately 96 percent of rated thermal power. The Reacto- Pressure Vessel [RPV) was at saturated conditions at ,

approximately 1015 psig. '

On August 30, 1990, a scheduled inspection determined that a CRHVAC backdraft damper was not operating properly. On August 31, 1990, at approximately 1430, maintenance activities were performed in which metal was removed f rom the duct to s allow proper movement of the backdraft damper. At 1730, a post-maintenance visual inspection of the CRHVAC system backdraf t damper revealed that a rectangular hole had been cut in the duct downstream of the damper. Temporary repairs to the duct were implemented and the system was considered to be operable. While evaluating permanent repairs, an investigation into the impact on system operability was commenced. On September 1, 1990, at 0110, it was determined that both trains of the Emergency Recirculation mode of CRHVAC were inoperable, due to the fact that potential leakage into the control room in the

, event of a design basis accident could have caused the radiation dose to inhabitants of the Control Room to exceed the design basis for exposure, and Technical Specification 3.0.3 was entered. The hole in the duct was patched and .;

welded and on September 1, 1990 at 0330, Technical Specification 3.0.3 was i exited. -Subsequently, it was also realized that any maintenance and inspection work which requires removal of the access panels in that portion of the duct, which is effectively a part of the common plenum, also causes the inoperability of both trains. Such activities had been performed on a scheduled basis since

.the beginning of plant operation.

-The "A" train of the Emergency Recirculation mode of CRHVAC system was already inoperable for previous maintenance as well as the work on the backdraft dam ^per, and in order to declare operability of the "A" train additional preplanned entries into the access panel (and therefore Technical Specification 3.0.3) were required to correct the backdraft damper problem. After management involvement and communications with the NRC, on September 2, 1990 at 1756, Technical Specification 3.0.3 was entered to remove the backdraft damper blades for machining. The access to the duct was closed after blade removal and Technical Specification 3.0.3 was exited at 1849. On September 2, 1990, at 2058, Technical Specification 3.0.3 was entered to install the machined damper blades. The work was successfully completed, the access was closed, and Technical Specification 3.0.3 was exited on September 2,1990 at 2212.

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ol7 lo - ojo oh 0F n l3 f9tf IF mum asase e sesasust, nur sumusener MC For* WW 1171 The cause of this event is program deficiency. The maintenance activities that i were being performed on the common plenum were not identified as causing both .

trains of the Emergency Recirculation mode of CRHVAC to be inoperable. Due to

i The CRHVAC system provides two independent trains of cooling, heating, j ventilation, and, when required, smoke removal for the control room and equipment l areas during normal plant operation and during periods of emergency 1 (loss-of-coolant accident, or high radiation conditions, or high toxic gas  !'

level). The Emergency Recirculation mode provides the necessary supplementary particulate and halogen filtration of the air supplied to the Control Room areas during emergency conditions and other abnormal conditions to reduce the radiation dose for personnel protection. During this event, with both trains considered inoperable, leakage into the Control Room in the event of a design basis accident j could have caused the radiation dose to inhabitants of the Control Room to exceed .,

the design basis for exposure. Initiation of the Emergency Recirculation mode of l CRHVAC would result in Control Room air being discharged outside of the Control Room envelope. The eventual decrease in Control Room pressure would result in '

negative Control Room pressure and in leakage in excess of desigu requirements.

Therefore, this event is considered to be safety significant. However, for regularly scheduled maintenance, it is reasonable to expect that, in the event of an accident, maintenance would have been halted and access covers could have been restored to allow proper system operation. j l

The Bases for Technical Specification 3.0.3 state that "It is not intended to be used as an operational convenience which permits (routine) voluntary removal of  ;

redundant systems or components f rom service in lieu of other alternatives that would not result in. redundant systems or components being inoperable" The two L. preplanned entries into Technical Specification 3.0.3 were not routine situations and there were no other alternatives which could have been performed to restore systeg operability. The two preplanned Technical Specification 3.0.3 entries were made with their duration purposefully limited.

I No other events involving maintenance activities which caused both trains of the

Emergency Recirculation mode cf CRHVAC to be inoperable have been previously reported. Research of previous maintenance and inspection activities reveals 1 that similar situations, in which access covers to the common plenum for the i -CRHVAC have been removed during power operation, have occurred numerous times.

ln Seven six month periodic maintenance tasks, four eighteen month periodic maintenance / inspection tasks, two as-required periodic maintenance tasks, and work associated with the tasks and equipment have been identified as potentially I

having been performed during power operation. These repetitive tasks are l

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010 0l4 0 14 i text in . - anc - anc., nn generally of a short duration and are easily secured f rom if an initiation of Emergency Recirculation should occur. Therefore, further investigation of exact number, dates, and times of such occurrences would not contribute to the .

effectiveness of corrective actions.

To prevent recurrence, maintenance activities and inspections which compromise the integrity of the control room envelope are being rescheduled to be performed i~ during plant outages. Applicable procedures are being revised to use additi m i 7

dampers for isolating Control Room Emergency Recirculation system plenums ptGr to opening plenum access covers for maintenance, testing, and inspection.

Engineering personnel are investigating potential design changes to improve '

reliability of the backdraft damper 2 or provide a means of isolating the Control Room Boundary to allow access to the back draft dampers without violating the Control Room Boundary. Investigation into a modification of the Technical Specification 3.7.2 Action Statements to allow system operation with a common

. plenum access cover removed.under. specific conditions is also in progress. An investigation into the naintenance activities which~resulted in the hole being cut in the duct has been completed using Iluman Performance Enhancement System (ilPES) techniques and the personnel responsible for cutting the hole in the duct have been counseled concerning the results of their actions.

Energy Industry identification System Codes are identified in the text as (XX).

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