ML19326A435

LER 78-035/03L-0:on 780408,hydrogen Dilution Blower 1-1 Motor Breaker Tripped on Overload During Test Run.Caused by Sticking Suction Check Valve.Valves Cleaned & re-assembled. Check Valve Internals Removal Requested

ML19326A435
Person / Time
Site:	Davis Besse
Issue date:	05/04/1978
From:	Isley T TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19326A434	List: ML19326A433 ML19326A435
References
LER-78-035-03L, LER-78-35-3L, NUDOCS 8002030257
Download: ML19326A435 (3)

Text

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EVENT oATg 1410 1817 18REPORT 34 75 ]@lo ATE0 l 510 80 l4I7l 3 3 63 61 coCKETAW.igER EVENT CESCRIPTION AND PROBABLE CONSEQUENCES h for testing when after about ik l lo t a l l On 4/8/78,. Hydrogen Dilution Blower 1-1 was running This olaced the unitj

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hours of run ti=e the blower motor breaker tripped on overload.

I io 6 A1 l in the Action Statenent of Tech Spec 3.6.4.3, which requiree both Evdrocen Dilution On 4/18/78 Hydrogen Dilution Blower l lo t s j l Systems to be operable while in Modes 1 and '

the discharee check valve I lo is i ] l-1 was again being operated when it was determined that bydrogen Dilution Blower l

[o l 7 l l vas not open, returning the unit to the Action Statenent.

l-2 was operable if an incident occurred requiring hydrocen dilution. CIP-33-78-43') 1 80 Io #a1 I j COMP. VALVE SYSTEM CAU$E CAUSE 'U8CooE SUSCooC CooE SUSCooE COMPONENT CooE CooE lc)9l l S l E l@ {@ l B l@ I V I A I L l V l E l X l@ l 19C l@ [A_j 18 20 @

10 1: 12 13 REVIS3cN 3 8 9 00CURRENCE REPORT '

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41 l4Al@ 64 47 33 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS The suction check valve I

,I go;l The cause of both of th ue occurrences is ce=ponent failure.

The dis- I g,,ij l vas found to be sticking and was disassenbled, cleaned, and reassembled.

Facility Chance 1 g charge check valve was disasse= bled, cleaned, and reassembled.-

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' equest 78-211 has been prepared to request removal of the check ' valve internals on f

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mql both Hydrogen Dilution Blowers to prevent recurrence. 80 7 8 9 of RY ol3CoVERY oESCRIPTioN oTHER STATUS l 3 jgl Surveillance Test ST 5065.05 h POWER l I1 15llEl@ l0l6l8lglE 10 12 31 44 l

45 46 80 7 8 9 ACTIVITY CONTENT LoCATloN oF RELEASE RELEASED oF RELEASE AMOUNT OF ACTIVITY l1 l6 l l El NA i' lM 80 44 45 7 8 9 10 11 PERioNNEL EXPOSURES NU .' E R TY'E oESCRl* Tion .l l1 l 7] l 0l l Z jA IO 11 12 13 7 8 9 PER$oNNE L INJVRIES y **s ga Ici,0l0]@!n o!$0RIPTioN **

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To: Isley pga.;g; ' 19-23 9-5000. Ext. Do I'7 N , v g - e s.,p u s,

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TOLEDO EDISON COMPANY -

DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION

• SUPPLD! ENTAL INFORMATION FOR LER NP-33-78-43 4

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DATE OF EVENT

April 8, 1978 FACILITY: Davis-Bessa Unit l' IDENTIFICATION OF OCCURRENCE: Hydrogen Dilution Blower 1-1 Trip 4

Conditions Prior to Occurrence: The unit was in Mode 1 vith Power (MWT) ranging from 1720 to 885, and Load (MWE) ranging from 560 to 625.

' Description of Occurrence: On April 8, 1978, Hydrogen Dilution Blower 1-1 was running for Surveillance Test ST 5065.05 " Hydrogen Purge Filter 18 Month or Special Test". After about ih hours of run time, the blower motor breaker tripped on overload. The technician at the blower had noticed no unusual noise while the blower was running. Shortly after the blower motor breaker tripped, j the operator attempted to reset the breaker but was unable to do so. This l blower being inoperable placed the unit in the Action Statement of Technical ,

- Specification 3.6.4.3, which requires both Hydrogen Dilution Systems to be op' era-  ;

ble while in Modes 1 and 2. The Action Statement requires the inoperable Hydro-gen Dilution System to be returned to operable status within 30 days or the unit be in Hot Standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. , ,

l On* April 18, 1978, Hydrcgen Dilution Blower 1-1 was again being operated for additional investigation of the previous failure. It was determined that the discharge check valve was not open and Hydrogen Dilution Blower 1-1 was again l declared inoperable at 1515 hours0.0175 days <br />0.421 hours <br />0.0025 weeks <br />5.764575e-4 months <br /> on April 18, 1978, returning the unit to the Action Statement of Technical Specification 3.6.4.3.

Designation of Apparent Cause of' Occurrence: The cause of both of these occur-rences is component failure. The suction check valve not fully opening was thought to be the cause of the first occurrence. Af ter further investigation, the discharge check valve was found to be not fully opening, causing the second occurrence.

t Analysis of Occurrence: There was no danger to the health and safety of the public or unit personnt.1. Hydrogen u:Liution Blower 1-2 was operable if an inci-dent requiring the Hydrogen Dilution 9ystem had occurred.

Corrective Action: On April 11, 1978, a heater in the breaker for Hydrogen Dilu-tion Blower 1-1 was replaced and the suction check valve was found to be stick-ing. On April 11, 1978, the velded bonnet suction check valve was disassembled, cleaned, and reassembled. Surveillance Test ST 5065.02, Hydrogen Dilution System Quarterly Test, was successfully perfor=ed for the Hydrozen Dilution Blower 1 which removed the unit from the Action Statenent of Technical Spefication 3.6.4.3.

v LER #78-035

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TOLEDO EDISON C0!!PANY PAGE 2 DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLCIENTAL INFORMATION FOR LER NP-33-IS-43 i

On April 24, 1978, the velded bonnet discharge check valve was disassembled, cleaned and, reassembled.

Facility Change Request 78-211 has been prepared to request removal of the 1

check valve internals on both Hydrogen Dilution Blowers to prevent recurrence.

A modification has been made to Surveillance Test ST 5065.02 to verify oper-ability of the check valves until they can be removed.

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l Failure Data: Although there has been no previous reportable occurrences, momentary sticking of these check valves has been experienced in'the past.

P Iza #78-035 O

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