ML19257A344

LER 79-121/03L-0:on 791130,while Moving Group 8 Rods,Rod 8-1 Was Noted Indicating 8% Lower than Group Average.Caused by Faulty Meter Movement.New Meter Installed

ML19257A344
Person / Time
Site:	Davis Besse
Issue date:	12/28/1979
From:	Werner J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19257A342	List: ML19257A341 ML19257A344
References
LER-79-121-03L, LER-79-121-3L, NUDOCS 8001030790
Download: ML19257A344 (2)

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o 2 l On November 30, 1979 at 0620 hours0.00718 days <br />0.172 hours <br />0.00103 weeks <br />2.3591e-4 months <br /> while moving the Group 8 rods, it was noted 1

l c 13 ) l that Rod 8-1 was indicating about 8% lower than the group average. This placed the While restoring Rod 8-1 to withinj o a j unit in the action statement of Tech Spec 3.1.3.2.

n s } 6.5% of the group average, the position indication jumped back up to agree with the l c ic j group average. There was no danger to the health and safety of the public or station 1 Only the j 0 7 [ personnel. The control rod never deviated from its intended position.

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[D l1 44 af CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h jijo]lThe cause of this occurrence was a faulty meter movement for the rod position indica- l l,gij [ tion on Control Rod 8-1. After the reactor shutdown on December 2, 1979, the meter  !

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-138 DATE OF EVENT: November 30, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Control Rod 8-1 faulty position indication meter Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT) = 1003 and Load (Gross FME) = 339.

Description of Occurrence: On November 30,1979 at 0620 hours0.00718 days <br />0.172 hours <br />0.00103 weeks <br />2.3591e-4 months <br /> while moving the Group 8 rods, it was noted that Rod 8-1 was about 8% lower than the group average as read by the absolute position indication (API). After switching over to relative position indication (RPI), the rod was still about 8% low. This placed the unit in the action statement of Technical Specification 3.1.3.2 which rcquires all axial power shaping rods be positioned to within 6.5% of their group average height while the unit is in Modes 1 and 2.

While restoring Rod 8-1 to within 6.5% of the group average, the position indication jumped back up to agree with the group average on both API and RPI. Subsequent movement of Group 8 showed Rod 8-1 position indication to remain in agreement with the group average thus removing the unit from the Technical Specification action statement.

Designation of Apparent Cause of Occurrence: The cause of this occurrence was a faulty meter movement for the rod position indication on Control Rod 8-1.

Analysis of Occurrence: There was no danger to the health and safety of the public or station personnel. The control rod never deviated f rom its intended position.

Only the position indication was faulty.

Corrective Action: Af ter the reactor shutdown on December 2,1979, the meter move-ment for Rod 8-1 position indication was removed for inspection under work request IC-55-26-79. It was discovered to be defective,and a new meter was installed on Decanber 2, 1979.

Failure Data: Although there have been previous failures of control rod position indication, no previous events were caused by def ective position indication meters, LER #79-121 1671 310