05000346/LER-1981-003-03, /03L-0:on 810106,breaker HX02B Tripped, de-energizing Bus B Which Reduced Electrical Distribution Less than Tech Specs Required.Caused by Personnel Error. Breakers Restored.Operators Counselled Re Attentiveness

/03L-0:on 810106,breaker HX02B Tripped, de-energizing Bus B Which Reduced Electrical Distribution Less than Tech Specs Required.Caused by Personnel Error. Breakers Restored.Operators Counselled Re Attentiveness

ML20003A923
Person / Time
Site:	Davis Besse
Issue date:	02/03/1981
From:	Kocis R TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20003A921	List: 05000346/LER-1981-003, Forwards LER 81-003/03L-0 05000346/LER-1981-003-03, /03L-0:on 810106,breaker HX02B Tripped, de-energizing Bus B Which Reduced Electrical Distribution Less than Tech Specs Required.Caused by Personnel Error. Breakers Restored.Operators Counselled Re Attentiveness
References
LER-81-003-03L, LER-81-3-3L, NUDOCS 8102100068
Download: ML20003A923 (2)

LER-1981-003, /03L-0:on 810106,breaker HX02B Tripped, de-energizing Bus B Which Reduced Electrical Distribution Less than Tech Specs Required.Caused by Personnel Error. Breakers Restored.Operators Counselled Re Attentiveness

Event date:
Report date:
3461981003R03 - NRC Website

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8 60 65 DOCKET NUYB ER 68 b3 EVENT D ATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h 0 2 l (NP-33-81-02) On 1/6/81 at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br />, a control room operator intending to match a 1

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[_g l N g l Z lg l Z l 9 l 9 l 9 lg 33 34 31 40 el 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h itIOllThe cause was personnel error by the operator. In attempting to match the switch flag l icolor with the breaker indication, he accidentally turned the switch-the wrong direc-I t i Restoration of the breakers was I g l tion even though he was aware of its function. l attained within 15 minutes. Operations personnel are being made aware of the occur-l i i l rence to emphasize the need for attentiveness while operating control devices. I i 4 80 7 8 9 STA % POWER OTHER STATUS DIS RY DISCOVERY DESCRIPTION y (_Dj@ l 0 l 0 l 0 l@l NA l W@l Operator Observation l ' A8riviTY CO# TENT AMOUNT OF ACTivtTY LOCATION OF RELEASE RELE ASED@OF RELE ASEW @l NA l l NA l (_Z) i 6 PERSONNE$ ExPOSuEc5 NUMBER TYPE

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-81-02 DAYE OF EVENT: January 6, 1981 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Breaker HXO2B, feeding vital Bus B, was tripped due to improper operation of the control switch Conditions Prior to Occurrence: The unit was in Mode 3 with Power (MWT) = 0 and Load (Gross MWE) = 0. Description of Occurrence: At 1600 hours on January 6, 1981, a control room operator inadvertently tripped breaker HX02B, which was feeding vital Bus'B, one of two 13.8 KV buses, which caused the de-energization of D1 (one of two 4160 volt essential buses) and F1 (one of two li80 volt essential buses). This reduced the electrical distribution to less than that required by Technical Specification 3.8.1.1, 3.8.2.1, and 3.8.2.3. The most restrictive action statement required the situation to be corrected within one hour. The breakers were all restored within 15 minutes. Designation of Apparent Cause of Occurrence: The in-house Electrical Dir ibution Panel, C-5715, located in the control room has incorporated into its layout a " mimic" bus providing visual representation of-the electrical bus lineup. Included in the representation are the hand indicating control switches (HIS) and " closed" indications for the bus breakers. The HIS rotates left or right from center and displays a green or red flag indicative of " trip" or "close" HIS operation. Since the colored flags are not affected by actual breaker position, an auto-transfer of a breaker would not change the flag indication on the HIS. Therefore, the control room operators routinely operate the HIS to correct a mismatch in flag color with respect to the breaker indicat-ing light. In this occurrence, the control room operator rotated the HIS in the wrong direction causing the closed breaker to trip. Analysis of Occurrence: There was no danger to the. health and safety of the public or to station personnel. Loss of the bus initiated an auto start and loading of the emerEency diesel which restored power to the vital electrical loads within 10 seconds.

Corrective Action

Since the cause was apparent, restoration began immediately with synchronization and closing of RX02B attained within 15 minutes.- Toledo Edison does not believe that a procedure or equipment discrepancy exists which indicates a ten-dency for recurrence. However, operations personnel will be,made aware of the occur-rence to emphasize the need for attentiveness while operating control devices. Failure Data: There has not been a previous report of this type of personnel error causing a breaker operation. LER #81-003 O m. m }}