05000440/LER-1994-001, :on 940118,sys Containment Isolation Occurred Due to Reactor Cleanup Sys Valve Nest Room High Differential Temp.Caused by Failure of Inlet Temp Switches.Ab Ventilation Sys Fans Inlet & Temp Switches Replaced

:on 940118,sys Containment Isolation Occurred Due to Reactor Cleanup Sys Valve Nest Room High Differential Temp.Caused by Failure of Inlet Temp Switches.Ab Ventilation Sys Fans Inlet & Temp Switches Replaced

ML20063K065
Person / Time
Site:	Perry
Issue date:	02/16/1994
From:	Lockwood D, Stratman R CENTERIOR ENERGY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-94-001, LER-94-1, PY-CEI-NRR-1757, NUDOCS 9402280149
Download: ML20063K065 (4)

LER-1994-001, on 940118,sys Containment Isolation Occurred Due to Reactor Cleanup Sys Valve Nest Room High Differential Temp.Caused by Failure of Inlet Temp Switches.Ab Ventilation Sys Fans Inlet & Temp Switches Replaced

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(x)
4401994001R00 - NRC Website

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CENTE~ LOR ENERGY PERRY NUCLEAR POWER PLANT Mail Address, Robert A. Stratman PO BOX 97 10 CENTER ROAD PE RRY, OHIO 44081 VICE PRESIDENT - NUCLEAR PERRY, OHIO 44081 (216) 259-3737 February 16, 1994 PY-CEI/NRR-1757 L U.S. Nuclear Regulatory Commission Document Control Desk Vashington, D.C.

20555 Perry Nuclear Power Plant Docket No. 50 440 LER 94-001 Gentlemen:

Enclosed is Licensee Event Report 94-001, " Reactor Vater Cleanup Isolation Due To Loss Of Auxiliary Building Ventilation."

If you have questions or require additional information, please contact Henry Hegrat - Regulatory Affairs, at (216) 280-5606.

Very truly yours,

/

Robert A. Stratman RAS:DHL:sc

Enclosure:

LER 94-001 cc: NRC Project Manager NRC Resident Inspector NRC Region III

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FORWARD LICENSEE EVENT REPORT (LER) cOMuENTs REGARxG suRDEN EsTwTE TO mE mOnem AND RECORDS MANAGEMENT BR/.NCH (MNBB 7714), U R. NUCLEAR Mf GJLATOHY COMMICSiON, V* ASHVJTON. DC 20f:tS 0301, AND TO THE FAPERINORK REDUCTION PG1ECT (3150 0104), OFFICE OF (See reverse for required number of digits / characters for each block)

MANAGEMENT AND suooET. v miNGTON, DC 20503 F ACILITV NAME (1)

DOCMI NUMBER (2)

PAGE (3)

Perry Nuclear Power Plant, Unit 1 05000 440 10F 3 Tll'Lt (4)

Reactor Water Cleanup Isolation Due To Loss Of Auxiliary Building Ventilation EVENT DATE (5)

LER NUMBER (6 REPORT NUMBER (7)

OTHER FACILITIES INVOLVED (8)

N H NAML DOGul NUUUL R se Out NT A ArvisiON uoNTn DAv vt An vtan uotan cAv vCAR 05000 f AC,IulY NAML DOCKET NUMBER 01 18 94 94 001 0

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MODE (9) 20 502(b) 20.405(c) x 50.73(a)(2)(iv) 73.71(b) 3405(a)(1Hi) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c) l POWER 20 405(a)(1 Hn) 50.36(c)(2) 50 73(a)(2)(vii)

OTHER LEVEL (10) j pc)7 20 405(a)(1)(iii) 50.73 ta)(2)(i) 50.73(a)(2)(viii)(A) thP'cW la Ab*'t below and in Text NRC 20 405(a)(1)(iv) 50.73(a)(2)(u) 50.73(a)(2)(vin)(B)

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LICENSEE CONTACT FOR THIS LER (12) l NAME ILLE PHONL NUMHLH pnclude Area Code)

David H. LockwOOd, Compliance Encineer Extension 7539 (216) 259-3737 COMPL.ETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAU!T SYSTE M COMMENT MANdFACTURER

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SYG'EM COMPONENT MANUFACTURER O RS SUPPLEMENTAL REPORT EXPECTED (14)

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ABSTRACT (Limit to 1400 spaces, i e., approximately 15 single-spaced typewntten knes) (16) i On January 18, 1994 at 0737 and 0738 system containment isolations occurred due to Reactor water Cleanup (RVCU) system valve nest room high differential temperatures.

I The high differential temperature occurred as a result of tripping of the Auxiliary Building (AB) Ventilation system supply fans due to lov inlet air temperature. The loss of cooling air to the valve nest room resulted in the high differential temperature.

At the time of these events outside air temperature was approximately minus 20 degrees Fahrenheit. The RUCU system was isolated at 0736 by plant operators in anticipation of the isolation signal. Plant operators verified that no leakage existed and the RVCU system was returned to service on January 21,1994.

Corrective actions were to replace the AB Ventilation system supply fans inlet temperature switches and relocate the associated *tapillary tubing.

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Introduction

On January 18, 1994 at 0737 and 0738 Reactor Vater Cleanup (RVCU) [CE] system containment isolations occurred due to valve nest room high differential temperature. At the time of these events the plant was in Operational Condition 1 (Power Operation) with reactor thermal power approximately 100 percent of rated and reactor vessel pressure approximately 1018 psig.

Notification was made in accordance with 10CFR50.72(b)(2)(ii).

This event is being reported in accordance 10CFR30.73(a)(2)(iv).

II.

Description of Event

On January 18,1994 at 0736 the RVCU system was shutdown with all containment isolation valves closed in anticipation of an isolation signal due to valve nest room high differential temperature. The valve nest room high differential temperature alarm vas received at 0735.

Prior to receiving this alarm the Auxiliary Building (AB) [VF] Ventilation system supply fans [ FAN] had tripped due to lov inlet air temperature.

Attempts to restart the supply fans were unsuccessful. At 0737 a Division 2 RVCU isolation signal was received due to RVCU valve nest room differential temperature. At 0738 a Division 1 RVCU containment isolation signal was also received.

Plant operators verified that no leak existed and the RVCU system was returned to service on January 21, 1994.

Investigation of the supply fans tripping indicated that one of three inlet air temperature switches (TS] in the common supply plenum had failed and that the associated capillary tubing for the switches required relocation to provide a more representative sample of inlet air temperature at the heating coils. At the time of the event outside air temperature was approximately minus 20 degrees Fahrenheit.

III. Cause of Event

These events are attributed to the failure of one of three inlet air temperature switches in the common supply fan plenum and a non-representative temperature indication at the inlet air heating coils.

The purpose of the temperature switches and associated capillary tubing is to protect the inlet air heating coils from freezing. The associated tubing was located in areas which sensed unheated supply air bypassing the heating coils.

The tubing was relocated to areas which ensured that air exiting the heating coils was properly mixed and heated prior to reaching the sensor.

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YE,AR NUMBER NUMBER 05000440 OF Perry Nuclear Power Plant, Unit i 94

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n,,-.-...-.~..__....--,n Investigation of the fan tripping determined that the failed switch could not be calibrated. A vork order, V.O. 94-0345, was generated and the switch replaced and calibrated successfully.

i IV.

Safety Analysis

The RVCU system is used to control reactor chemistry, reduce reactor water inventory during startup and shutdown, minimize temperature gradients when recirculation pumps are not operating.

A RUCU containment isolation at high reactor power may cause reactor coolant conductivity to slowly increase until the system is returned to service. In this event, RVCU was returned to service before Technical Specification action requirements were exceeded. The RVCU system valve nest room differential temperature detection is part of the Leak i

Detection system, designed to isolate the RUCU system containment penetrations should a RUCU system leak develop.

Since no system leakage existed and the RWCU system was not challenged due to being manually isolated prior to the isolation signal, this event had no safety significant consequence.

V.

Similar Events

Previous RVCU isolations as a result of AB Ventilation problems are documented on LER's88-010, 88-016, and 89-004. However, none of these events involved problems with the inlet air temperature switches and associated capillary tubing.

I The RVCU system was not manually isolated prior to the isolation signal being

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generated for any of the previous events.

VI.

Corrective Actions

At the time of the AB Ventilation fans tripping investigation was initiated to determine the cause. Replacement of the temperature switch and relocation of the associated capillary tubing was completed and the AB Ventilation system returned to service on January 19, 1994.

Similar capillary tubing location problems were identified in the Intermediate Building Ventilation (VE] system and corrected.

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Four other plant ventilation systems utilizing similar switches and tubing did not experience tripping due to lov inlet air temperature and therefore relocation of the tubing for these systems was not performed.

Further corrective actions are addressed on Condition Report 94-032.

Energy Industry Identification System (EIIS) codes are identified in the text as [XX].

NnC FonM assA e e.,