ML19305D771

LER 80-008/03L-0:on 800305,while Performing LPCI & Containment Cooling Modes,Two 5-S Delay Timers for Starting 1002D RHR Pump Failed to Actuate Timer Contacts.Caused by Microswitch Arm Being Out of Alignment

ML19305D771
Person / Time
Site:	Quad Cities
Issue date:	03/26/1980
From:	Hoeller J COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19305D751	List: ML19305D750 ML19305D771
References
LER-80-008-03L-04, LER-80-8-3L-4, NUDOCS 8004150498
Download: ML19305D771 (2)

Text

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSl!N (7J7)

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7 8 60 61 DOCKET NUMBER 68 69 EVENT DATE 74 75 REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h

[5TT] l While performing the LPCI and Containment Cooling Modes of RHR Logic Test, procedure I i lO lal l QMS 700-2, two 5-second delay timers for starting of the 1002D RHR pump (timers l 1 io g4; l 10A-MIB and 10A-M2B) failed to actuate the timer contacts. The two remaining timers l i o 3 l In the one-out-of-two-twice logic circuit tested satisfactorily. Subsequently, the l l 0 l6 l l logic Circuit would have operated as designed and started the 1002D RHR pump in the l ITTTl I required 5 seconds. Testing was being done in accordance with Technical Specificatiop  ;

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44 47 L CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l i 10 l l The 10A-MlB timer contact micro-switch arm was out of alignment, preventing closure l lil3l l of contacts 8 and 9 The 10A-M2B timer was found to have improper spring tension on I (

,,,,, l the timer clutch mechanism. This inhibited the timer cam from operating. The limit l l g,l3ll switch arm on timer 10A-MlB and the clutch spring tension on timer 10A-M2B were l gl adjusted and both timers were retested satisfactorily. l 7 8 9 80 ST  % POWER OTHER STATUS IS RY DISCOVERY DESCRIPTION lT]T) J@ l 0l 0]0l@l NA l l q@l Routine Test l ACTIVITY CO TENT RELEASED OF RELEASE AMOUNT OF ACTivlTY LOCATION OF RELEASE 1116 I l Zl @ l Zlgl NA l l NA- l l PERSONNEL EXPOSt ES NUMBER TYPE OESCRIPTION y l 0l 0l 0l@l Zl@l NA l j

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1. LER NUMBER: LER/R0 80-08/03L-0

11. LICENSEE NAME: Commonwealth Edison Company Quad-Cities Nuclear Power Station Ill. FACILITY NAME: Unit Two IV. DOCKET NUMBER: 050-265 V. EVENT DESCRIPTION:

• L On March 5,1980, while performing the LPCI and Containment Cooling Modes of RHRS Logic Test, procedure QMS 700-2, timers 10A-MIB and 10A-M20 failed to actuate the timer contacts.

These timers, part of a one-out-of-two-twice logic scheme, are [

used to delay the starting of the 1002D RHR pump. The remaining '

timers in the circuitry, 10A-M3B and 10A-M48, were tested satisfactorily. The testing of the LPCI and Containment  ;

Cooling modes of the RHR system was being performed in accordance ,

with Technical Specification 4.5.A.3 [

VI. PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The starting of the 1002D pump is delayed to prevent overloading l of the diesel generator. Although both 10A-MIB and 10A-M2B ,

timers failed to operate properly, the one-out-of-two-twice  ;

logic circuitry would have performed its intended function i through timers 10A-M3B and 10A-M48. Thus, the 1002D pump '

would have started in the required 5 seconds. Overall plant safety was not affected by this occurrence.

Vll. CAUSE:

The designated cause of this occurrence is equipment failure. r in the case of timer 10A-MIB, the timer contact micro-switch arm was out of alignment preventing closure of contacts 8 and 9 For timer 10A-M2B, the problem was discovered to be improper spring tension on the timer clutch mechanism. This was inhibiting the timer cam from operating. The timer units are manufactured by Hayden Manufacturing Company.  ;

Vill. CORRECTIVE ACTION: I The limit switch arm for contacts 8 and 9 on the micro-switch j for timer 10A-M1B was adjusted. The spring tension on the timer clutch of timer 10A-M2B was also adjusted and both timers were retested satisfactorily.

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