ML19326A088

LER 78-074/03L-0:on 780625,containment Isolation Valves CC 1407B & CC 1411B Failed to Operate When Automatically Actuated.Caused by Broken Wires,Probably Due to Strain Caused During Outage.Wires Repaired & Scheme Tested

ML19326A088
Person / Time
Site:	Davis Besse
Issue date:	07/20/1978
From:	Albert J, Kovach S TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19326A086	List: ML19326A085 ML19326A088
References
LER-78-074-03L, LER-78-74-3L, NUDOCS 8001310655
Download: ML19326A088 (3)

Text

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, o g l vere thus inoperable. There was no danger to the health and safety Of the public or 10 i s I l unit personnel. Each inonerRhlva valve is one of evn Anuhle i=olaf. inn valves. The l O 6 l redundant valve would, therefor *. h8"e "rovided coStaiS**nt f

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I i l O l \Several wires were found broken at connectors. The wire breaks were mOst erobablv y l caused by working in close proximity tO the cOnne/ tors durine the outace. The brokan i l

i1 12 I l wires were repaired. ,

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- TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-78-88 DATE OF EVENT: June 25, 1978 FACILITY: Davis-Besse Unit.1 IDENTIFICATION OF OCCURRENCE: Containment Isolation Valves CC 1407B and CC 1411B inoperable .

4 Conditions Prior to Occurrence: The unit was in Mode 5, with Power (NWT) = 0, and Load (MWE) = 0. .

Description of Occurrence: At.1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br /> on June 25, 1978 during performance of Surveillance Test ST 5031.07, " Safety Features Actuation System 18 Month or Refueling Test", Containmant Isolation Valves CC 1407B and CC 14113 did not operate when actuated from an automatic test signal. .The valves were thus in-

operable. ,

l 7 Technical Specification 3.6.3.1 requires that these containment isolation valves be operable in Mod 7s 1, 2, 3 and 4. Since the unit was in Mode 5 at the time of' 4

S the occurrence, the Action Statement was not applicable. This occurrence is be-4.ing reported as documentation of a component failure.

Designation of Apparent Cause of Occurrence: CC 1407 had a broken wire external to the cabinets in cable. spreading room. This appears to be an isolated failure.

Several wires were found broken at connectors which link Safety Features Actua-tion System (STAS) Channels 2 and 4. The broken wires were on the cabinet side wiring in Channel 4. The wire breaks were probably caused by strain on.the ,

wire due to the ,iumpering of DH-11 for testing during the outage, or possibly due to other routine access to cabinet 4 during the outage.

Analysis of Occurrence: There was no danger to the health and safety of the public or to unit personnel. Each inoperable valve is one of two double isolation -

vavles. The redundant valve would, therefore, have prom ded, containment isolation at each location if required. If an event requiring these valves te'be closed -

had occurred, the operator would have been able to close these valver using the

' control room switch, 4

Corrective Action: The broken wires were repaired. All wires, except those which are part of spare circuits or have yet to be functionally tested in other tests, were scheme checked. The valves were returned to operability on June 30, ,'

1978. .

LER #78-074 5

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• TOLEDO EDISON CCEPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-78-88 PAGE 2 0F 2 Failure Data:

There have been no previous reportable occurrences.

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LER #78-074 .

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