ML20028B228

LER 82-053/03L-0:on 821018,half Trip Alarm on Steam & Feedwater Rupture Control Sys Channel 2 Received Due to Failure of Steam Generator Level Instrument Cabinet Channel 2,24-volt Dc Power Supply.Caused by Component Failure

ML20028B228
Person / Time
Site:	Davis Besse
Issue date:	11/16/1982
From:	Yarger K TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20028B224	List: ML20028B223 ML20028B228
References
LER-82-053-03L, LER-82-53-3L, NUDOCS 8211300187
Download: ML20028B228 (2)

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• LICENSEE EVENT REPORT

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7 8 DOCK ET NUMBER EVENT DESCRIPTION AND PROBA8LE CONSEQUENCES h 10 l a l I (NP-33-82-64) On 10/18/82 at 1222 hours0.0141 days <br />0.339 hours <br />0.00202 weeks <br />4.64971e-4 months <br />, the Control Room operators received a half l g 3 trip alarm on the Steam and Feedwater Rupture Control Syst'em (SFRCS) Channel 2. Invesj-g , ;tigation showed that the trip was due to failure of the Steam Generator Level Instru- l g , g ment Cabinet Channel 2', 24 VDC power supply. This invoked T.S. 3.3.2.2, Action Item l

, , which required the Channel to be tripped within one hour. There l 0 6 l ggg,; lwas no danger to the public or station personnel. The loss of the power supply trippe(

y g ,g i g the channel and placed it in the mode required by Technical Specifications and design.l 0 E CODE S BC E COMPONENT CODE SUBCbdE S E 7

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, CAUSE DESCRIPTsON AND CORRECTIVE ACTIONS h l 110 l IComponent failure has caused the overvoltage trip device to trip the power supply. I i , l0n 10/18/82 at 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br />, a new power supply was installed under Maintenance Work I

, , g0rder IC-587-82. Surveillance Test ST 5031.14 was performed, and the channel was l

, 3 l declared operable at 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on 10/18/82. This removed the plant from Technical l 3 4  ; Specification 3.3.2.2, Action Item (b), Statement 13. l 7 8 9 80 ST S  % POWER OTHER STATUS DIS O RY DISCOVERY DESCRIPTION li 15 l [Ej@ l 0 l 8 l 5 l@l NA l l A l@l Operator Observation l ACTIVITY CO TENT RELEASED OF RELEASE AMOUNT OF ACTIVITY LOCATION oF RELEASE 1 6 [Zj @ [Zj g l NA l l 45 NA -

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PERSONNE L INJURIES 0211300187 821116 l' NUMBER DESCRIPTION @ PDR ADOCK 0500C 346 i a S PDR l l 0 l 0 l 0 l@l12NA 80 7 8 9 11 LOSS OF OR DAMAGE TO FACILITY TYPE DESCRIPTION i 9 l 7 8 9 l Z l@l10NA 80 iS 2 o E @DESCRiPT60N lNA l lllllllllllllj 7 4 9 TO 68 69 80 $

DVR 82-123 t Yarger PHONE:

NAN 1E OF PREPARER

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-82-64 DATE OF EVENT: October 18, 1982 -

FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Failure of the +24 VDC power supply for Steam Generator Level Instrument Cabinet (SGLIC) Channel 2.

Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT)

= 2372 and Load (Gross MWe) = 800.

Description of Occurrence: On October 18, 1982 at 1222 hours0.0141 days <br />0.339 hours <br />0.00202 weeks <br />4.64971e-4 months <br />, the Control Room operators received a half trip alarm on the Steam and Feedwater Rupture Control System (SFRCS) Actuation Channel 2.

Investigation showed that the trip was due to failure of the SGLIC Channel 2, 24 VDC power supply. This power supply provides the current for ET-SP9B6, Steam Generator i level. input for SFRCS Channel 2. When the power supply tripped, it simulated a loss of level on Steam Generator 1 tripping SFRCS Channel 2.

This invoked Technical Specification 3.3.2.2, Action Item (b), Statement 13 which required the channel to be tripped within one hour. The failure of the power supply provided this action automatically.

Designation of Apparent Cause of Occurrence: A component failure has caused the overvoltage trip device to trip the power supply. The input voltage was checked and found to be normal. The power supply was then replaced to ensure plant stability. The failed power supply will be sent to the manufacturer, Sorensen Company, for analysis and repair.

Analysis of Occurrence: There was no danger to the health and safety of the public or station personnel. The loss of the power supply did trip the channel and placed it in the mode required by Technical Specifications and design.

Corrective Action: On October 18, 1982 at 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br />, a new power supply was installed under Maintenance Work Order IC-587-82. Surveillance Test ST 5031.14 was performed, and the channel was declared operable at 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on October 18, 1982. This removed the plant from Technical Specifi-cation 3.3.2.2, Action Item (b), Statement 13.

Failure Data: This is the tenth failure of a Sorensen power supply, however, only one failure has occurred within the last twelve months; reference Licensee Event Report NP-33-82-60 (82-051) which involved the failure of a 48 VDC power supply.

LER 82-053

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