ML19296D441

LER 80-012/03L-0:on 800201,operator Noticed Loss of Control Room Position Indication for Letdown Cooler Isolation Valve MU2A.Caused by Design Deficiency.Apparently,Someone Brushed Up Against Disconnect Breaker Switch.Switch Repositioned

ML19296D441
Person / Time
Site:	Davis Besse
Issue date:	02/28/1980
From:	Stotz J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19296D434	List: ML19296D433 ML19296D441
References
LER-80-012-03L, LER-80-12-3L, NUDOCS 8003040590
Download: ML19296D441 (3)

Text

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b' id t> J 15 Et EN T DA TE 74 REPORT G AIE EJ EVU.T DE;Cn!PT!CN AND PROB AGL E CC'.3E QJE*.CEO h o 2 lOn 2/1/80 at 1222 hours0.0141 days <br />0.339 hours <br />0.00202 weeks <br />4.64971e-4 months <br />, a reactor operator noticed that he had lost control room posiq a 3, jtion indication for letdown cot.er isolation valve MU2A. A check of the disconnect o;a [ switch breaker showed t he switch midpositioned between the nornal and local position.  ;

a s [Thir meant that the valve could not be actuated from the control room or on a safety 9

g g l Features Actuation level 2 initiation. This placed the unit in the action statement of j

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[T.S. 3.6.3.1. There was no danger to the health and safety of the public or station  ;

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ipersonnel. The redundant isolation valve MU3 was opuable. (NP-33-80-16) 7 8 9 l

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43 41 42 43 44 41 CAU5E Dt;CRiPTICN AND COHnECTIVE ACTIONS h i o [ Tlje cause was desian deficiencv.

Soncone apparent 1v brushed up against the disconnect ,

g g jswitch breaker which is located in a heavily traveled hallway. Operators reported conq

, 7 l tractors working above the breaker during this time making for more congestion. The  ;

i ,3 [ switch was immediately repositioned and indication returned to the control room. A l

,g,g gceco was issued to station personnel. Fcx 77-234 Supplement 2 has been completed.

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DVR 80-021' NAVE OF PREPARER Jan C. Stotz PHONE:

419-259-5000, Ext. 243 o a

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TOLEDO EDISON COMPANY

' DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLE'iENTAL INFOR!L\ TION FOR LER NP-33-80-16 DATE OF EVENT: February 1, 1980 FACILITY: Davis-Besse Unit 1 IDE!!TIFICATION OF OCCURRENCE: Disconnect switch for letdown cooler isolation valve MU2A found out of position The unit was in Mode 1, with Power (5C[) = 2764, Conditions Prior to Occurrence:

and Load (Gross FME) = 922.

Description of Occurrence: On February 1,1980 at 1222 hours0.0141 days <br />0.339 hours <br />0.00202 weeks <br />4.64971e-4 months <br />, a reactor operator noticed that he had lost control room position indication for FT2A, which also meant that he could not operate it from the control room. An equipment operator was dispatched to the disconnect switch breaker. He found the disconnect switch in the midposition between normal (operable from control room) and the local posi-tion. This meant that the valve would not have actuated to its safety position The disconnect upon a Safety Features Actuation System (SFAS) level 2 initiation. Technical Specifica-switch was immediately returned to the normal remote position.

tion 3.6.3.1 requires this containment isolation valve to be operable with an isola-Therefore, the unit tion time of less than 15 seconds while in Modes 1, 2, 3, and 4.

had temporarily entered the action statement which requiredleast the inoperable valve be hot standby within restored to operable status within four hours or be in at the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in cold shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

4 Designation of Apparent Cause of Occurrence: This occurrence is attributed to deaign deficiency. This type of switch (CE Type SB-1) with a pistol grip handle is easily bumped out of position and can stick in mid-position. This prevents both remote and local operation and also prevents SFAS actuation of the valve. The new switch (GE Type SB-9) to be installed per Facility Change Request 77-234 Revision A will This will eliminate the possibility of hanging up between contacts (mid-position).

always insure SFAS's ability to actuate the valve. Someone apparently bumped into this switch and did not realize it was now out of position. The breaker is located in a heavily traveled hallway on the 585' leve' outside the #2 mechanical penetration room. Operatorr reported there had been outside contractors working above the breaker during this time, which made the hallway even more congested. It is possible that someone brushed up against the switch handle while stepping around the scaffolding.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. Its redundant isolation valve MU3 was operable.

Corrective Action: On February 1, 1980, at 1226 hours0.0142 days <br />0.341 hours <br />0.00203 weeks <br />4.66493e-4 months <br />, an equipment operator re-turned the disconnect switch to its normal remote position. This restored control room indication of the valve position. This removed the unit from the action statement of Technical Specification 3.6.3.1.

A memo has been issued to all station personnel to emphasize the importance of these

' switches and the need to report to the control room any accidental contact with a breaker or any plant equipment, even if it appears that nothing has been affected.

LER #80-012

TOLEDO EDISON CO:!PANY DAVIS-BESSE SUCLEdR POWER STATION C';IT ONE PAGE 2 SUPI LEMENTAL INFORMATION FOR LER NP-33-80-16 Facility Change Request 77-234 Supplement 2 has been issued to remove the handles from the switches as a temporary correction until the switches can be replaced.

This work has been completed.

Failure Data: Previous equipment inoperabilities cue to cisconnect switenes being out of the local position were reported in Licensee Event Reports NP-33-77-38 and NP-33-77-45. ,

LER #80-012 i

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