05000346/LER-1981-013-03, /03L-0:on 810218,control Room Normal Ventilation Dampers Tripped Shut Resulting in No Power Available to Chlorine Detector 1 Above Control Room or in Block House. Caused by Failure of 10 Amp Fuse of Circuit Y111

/03L-0:on 810218,control Room Normal Ventilation Dampers Tripped Shut Resulting in No Power Available to Chlorine Detector 1 Above Control Room or in Block House. Caused by Failure of 10 Amp Fuse of Circuit Y111

ML19347D635
Person / Time
Site:	Davis Besse
Issue date:	03/20/1981
From:	Frohne R TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19347D633	List: 05000346/LER-1981-013, Forwards LER 81-013/03L-0 05000346/LER-1981-013-03, /03L-0:on 810218,control Room Normal Ventilation Dampers Tripped Shut Resulting in No Power Available to Chlorine Detector 1 Above Control Room or in Block House. Caused by Failure of 10 Amp Fuse of Circuit Y111
References
LER-81-013-03L, LER-81-13-3L, NUDOCS 8103260913
Download: ML19347D635 (2)

LER-1981-013, /03L-0:on 810218,control Room Normal Ventilation Dampers Tripped Shut Resulting in No Power Available to Chlorine Detector 1 Above Control Room or in Block House. Caused by Failure of 10 Amp Fuse of Circuit Y111

Event date:
Report date:
3461981013R03 - NRC Website

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U. S. NUCLE AR HEGUL ATORY COMMISSION NRC FORM 36G 0 77)

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E3 61 DoCKE T NUYBE R 68 63 EVENT D AT E 74 75 REPORT DATE 80 EVENT OESCRIPTION AND PROBABLE CONSEQUENCES h l(NP-33-81-12) On 2/18/81 at 0430 hours0.00498 days <br />0.119 hours <br />7.109788e-4 weeks <br />1.63615e-4 months <br />, control room normal ventilation dampers I

o 2 1 tripped shut. No power was available to Chlorine Detector 1 above the control room l

o a lor to Chlorine Detector #1 in the block house by the chlorine car.

The chlorine de-l 0 4 lo I s l ;tection system was declared inoperable, and the station entered the action statement l

lof Technical Specification 3.3.3.7.

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- CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h Essential y lThe cause was the failure of the 10 anp fuse of circuit Y111-in the l120 VAC Instrument Distribution Panci Yl.

This caused a loss of the #1 side c;ilorine i i i

,,,7, l detectors. Under NWO 81-1019, the blown fuse was replaced, and the detectors restored [

g lto operable. The CR EVS was shutdown, and the normal control room ventilation started l g lat 0525 hours0.00608 days <br />0.146 hours <br />8.680556e-4 weeks <br />1.997625e-4 months <br /> on February 18, 1981.

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-81-12 DATE OF EVENT: February 18, 1981 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE:

Control Room Ventilation Chlorine Detection System inoperable Conditions Prior to Occurrence: The unit vae in Mode 1, with Power (MRT) = 2772 and Load (Gross MWE) = 920 Description of Occurrence: On February 18, 1981 at 0430 hours0.00498 days <br />0.119 hours <br />7.109788e-4 weeks <br />1.63615e-4 months <br /> the control room ventilation dampers tripped shut. An investigation showed no power available to the Chlorine Detector 1 above the control room or to the Chlorine Detector 1 in the block. house. The Chlorine Detection System was declared inoperabic. The sta-tion entered the Action Statement (a) of Technical Specification 3.3.3.7 which required that within one hour the station initiate and maintain operation of the control room ventilation system in the recirculation mode of operation. The Control Room Emergency Ventilation System was placed in recirculating mode within the one hour required limit.

Designation of Apparent Cause of Occurrence: The cause of this event is a failure of the 10 amp fuse in the Essential 120 VAC Instrument Distribution Panel "Y1" for circuit Yll1. This caused a loss of the #1 side chlorine detectors. Due to an increased load in this circuit (added heat tracing) the fuse size was not ade,quate.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. -The loss of power to the chlorine detectors caused the nor-mal ventilation' damper to close.per design. The control room emergency ventilation system was then available to maintain the control room habitat.

Corrective Action

Maintenance electricians replaced the blown fuse the same morning

.under Maintenance Work Order 81-1019. This restored the chlorine detection system s to _ an operable condition and removed the station from Action Statement (a) of Techni-cal Specification 3.3.3.7.

The control room emergency ventilation system was shutdown, and the normal control room. ventilation was started at 0525 hours0.00608 days <br />0.146 hours <br />8.680556e-4 weeks <br />1.997625e-4 months <br /> on February'18, 1981.

Facility Change Reques't 77-356 Supplement 7 calls for a 15 amp fuse to be in circuit Y111~in lieu of the 10 amp.

Supplement 7 is.now being' implemented "in part" to in-stall the correct fuse size.-

4 Failure Data: Previous failures of the chlorine detection' system were reported in Licensee Event Reports NP-33-77-31 and NP-33-77-108.

LER #81-013