ML19326A347

LER 78-079/03L-0:on 780716,decay Heat Cooler Outlet Valve Dh 14A Would Not Open.Caused by Misaligned Actuator Arm,Due to Vibration or Faulty Installation.Actuator Arm Shifted to Correct Position & Set Screw Tightened

ML19326A347
Person / Time
Site:	Davis Besse
Issue date:	08/11/1978
From:	Kovach S TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19326A270	List: ML19326A268 ML19326A347
References
LER-78-079-03L, LER-78-79-3L, NUDOCS 8002030164
Download: ML19326A347 (3)

Text

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Nyuggm 6d 63 EVENT DATE 14 75 REPORT oATE SJ EVENT DESCRIPTION AND PROS A8LE CONSEQUENCES h I o 121 1 On July 16,1978 at 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br />, the Decay Heat Cooler 1-2 Outlet Valve DH 14A was I f

gi found to be inoperable and would not open. Reactor Coolant System temperature on I

io,,i l Decay Heat Loop 2 could not properly be controlled. Decay Heat Loop 2 was removed gg[ from service and Decay Heat Loop 1 placed in service. There was no danger to the I io g il health and safety of the public or unit personnel. The unit was in Mode 5 at the l (NF-33-78-94) i lo;;; j time of the occurrence.

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4 4A 47 CAuSE DESCRIPTION AND CORRECTIVE ACTIONS liioil The actuator arm was found to have moved with respect to the shaft. It is suspected I

,,,,i i that the reason that the screw loosened was either vibration or faulty installation.  ;

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,, , ,, [ Instrument and Control technicians shifted the actuator arm to its correct position The valve was tested and returned to operable status. I g l and tightened the set screw.

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7 4 3 10 DVR 78-125 Sue Kovach pwong; 419-259-50nn Zxt. 2?n E NAME OF PREPARER

TOLEDO EDISON COMPANY '

DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION -

SUPPLEMENTAL INFORMATION FOR LER NP-33-78-94 DATE OF EVENT _: July 16, 1978 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Decay Heat Cooler 1-2 outlet valve DH 14A inopera-ble The unit was in Mode 5, with Power (MWT) = 0,

. Conditions Prior to Occurrence:

and Load (MWE) = 0.

Description of Occurrence: On July'16, 1978 at 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br />, Decay Heat Cooler 1-2 Outlet Valve DH 14A was found to be inoperable, and would not open. Reactor Coolant System temperature on Decay Heat Loop 2 could not properly be controlled.

Decay Heat Loop 2 was removed from service and Decay Heat Loop 1 placed in ser-vice.

No Technical Specification or Action Statement was applicable; this report is being submitted as documentation of component failure. Amendment 3 to the

' Davis-Besse Unit 1 operating license requires, however, that an operator be stationed in the Control Room when only one decay heat removal train is avail-able for operation. This action is required to assure that the decay heat removel pump (s) can be immediately secured snould loss of flow occur due to the inadvertent closure of decay heat isolation valves DH11 and DH12.

Designation of Aoparent Cause of Occurrence: Ihe actuator arm on HV DH14A was found to have moved with respect to the shaft. The actuator' arm and shaft are connected by a key in which a screw had loosened. The reason that the screw loosened was either vibration or faulty installation. ,

Analysis of Occurrence: There was no danger to the health and safety of the public or unit personnel. The unit was in Mode 5 at the time of the occurrence.

Decay Heat Loop 1 was operable and was.placed in servir:e during the period that Decay Heat Loop 2 was out of service. In addition, an operator was stationed in the Control Room during this time.

Corrective.' Action: Under Maintenanta Work. Order ifC 312-73, Instrument and Control technicians sliif ted the actuator arm *.o cr i ' rect position with res-pect to the'sfikfe and tigEtened the set screw. 1 (D

-() LER J78-079 o

l t,

TOLEDO EDISON COMPANY {

DAVIS-BESSE UNIT ONE NUCl%&R POWER STATION PAGE 2 SUPPLEMENTAL INFORMATION FOR LER NP-33-78-94

.After stroking the valve per Surveillance Test ST 5051.01, " Emergency Core Cool-ing System Subsystem Monthly Test", DH14A was declared operable at 1345 hours0.0156 days <br />0.374 hours <br />0.00222 weeks <br />5.117725e-4 months <br /> on July 16. The operator watch in the Control Room was discontinued at this time.

Failure Data: Previous component failures with decay heat valves have been There have reported in Licensee Event Reports NP-32-77-08 and NP-33-77-26.

been no previous problems, however, with actuator arms on decay heat valves. i LER #78-079 i

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