ML20024A534

LER 83-023/03L-0:on 830510,120-volt Ac Essential Bus Y4 Lost,Resulting in Deenergizing Reactor Protection & Safety Features Actuation Sys Channel 4.Caused by Blown Fuse in Inverter YV4.Power Restored to bus.W/830608 Ltr

ML20024A534
Person / Time
Site:	Davis Besse
Issue date:	06/08/1983
From:	Murray T, Rowland M TOLEDO EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
K83-850, LER-83-023-03L, LER-83-23-3L, NUDOCS 8306170414
Download: ML20024A534 (3)

Text

.

NRC FOIM 366 U.S. NUCLEAR REGULATORY COMMISSION (7 77) ,

• LICENSEE EVENT REPORT CONTROL BLOCK: l l l l l  ! l (PLEASE PRINT OR TYPE ALL REQUIRED IOORMATION) 1 6 10111 l Ol Hl Dl Bl Sl 1l@l O l 0 l -l 0 l 0 l 0 l 0 l 0 l -l O l 0 l@l 4 l 1 l l j 1l 1l@l 8 9 14 15 LICENSE NUMBER 25 26 LICENSE TYPE JO l

57 CAT 58 lg 7 LICENSEE CODE CON'T Iol11 3$"c'lLl@l015 l0 l0DOCKET l0 l3 l4 l6 @l 680 l 695 l 1 EVENT l 0 lDATE 8 l 3 l@l 075l 6 lREPORT 0 l 8DATE l 8 l 380l@

7 8 60 61 NUMBER 74 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 l(NP-33-83-32) On 5/10/83 at 1026 hours0.0119 days <br />0.285 hours <br />0.0017 weeks <br />3.90393e-4 months <br />, 120 VAC essential bus Y4 was lost due to a l

o ; 3, l blown fuse in inverter YV4. This placed the unit in the action statement of Tech Spec; i o ,4 ; l3.8.2.1. As a result of the loss of Y4, the following Tech Spec instrumentation was l g gde-energized

Reactor Protection System Channel 4 and Safety Features Actuation Systeg l 016 l l Channel 4. There was no danger to the health and safety of the public or station per g j o l 7 ] lsonnel. All safety systems performed as designed. l 1 o 181 l l 80 7 8 9 E CODE S BC E COMPONENT CODE SUSCODE SU E g

7 8 l El Bl@ ]@ W@ lC lK lT lB lR lK l@ lX l@ { @

9 to 11 12 13 18 19 20 SEQUENTIAL OCCUR R ENCE REPORT REVISION LER/Ro EVENT YE AR REPORT NO. CODE TYPE N hR y l8l3l l_l l0l2l3l y l0 l3 l lL l g {O.

_ 21 22 23 24 26 27 28 M 30 31 32 K N AC O PLANT ME HOURS 22 SB f FOR 8. SUPPL 1 MANUF CTURER lH [g]34Z l g ]35g [Gjg l0l0l1l 37 l lYlg 41 lNlg lZ g lZl9l9l9lg 33 36 40 42 43 44 47 CAUSE DESCRIPTION AND CORRCCTIVE ACTIONS 27 g lWhile performing modification work in the Low Voltage Switchgear Room 2, a spray can l g lbeing used tipped over, spraying water onto the protective plastic on the scaffolding.l li12i lAs a result, water worked its way through the plastic into the regulated rectifier YRF4g i,i3g land caused the inverter YV4 input fuse to blow. Y4 was restored at 1336 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.08348e-4 months <br /> on l g l5/10/83. A memo was issued outlining precautions to be taken while erecting scaffoldiqg 80 uETHOo O, over electrical equip nt.

' r ACitiTY DISCOVERY DESCRIPTION 32 STATUS *6 POWER OTHER ST ATUS DISCOVERY ITTil W@ l 01910l@l NA l l A [gj Operator Observation l 80 ACTIVITY CO TENT AMOUNT OF ACTIVITY LOCATION OF RELEASE .

7 1 6 F.ELEASED@OF 8 9 10 11 RELEASE l NA 44 l l NA 45 30 l

PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION

[1_[7.,j l 0 l 0 l 0 Ihl Z lhl NA l

' PERSONNEt INJURIES NUMBER 1 H l 0 l 0 l 0 lhl NA DESCRIPTION 8 l

8306170414 830608 OSS OF OR D AGE TO FACILITY 4 PDR ADOCK 05000346 TYPE DESCRIPTION 1 9 lZlglNA S PDR l

7 8 9 10 ISSUED DESCRIPTION 2 O [ l M l llllllllll lll*g {

7 8 9 10 68 69 80 ;E DVR 83-059 NAME OF PREFARER PHONE:

,ep .

TOLEDO

%mm E s ISON June 8, 1983 Log No. K83-850 File: RR2 (NP-33-83-32)

Docket No. 50-346 License No. NPF-3 Mr. James G. Keppler Regional Administrator, Region III Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137

Dear Mr. Keppler:

LER No.83-023 Davis-Besse Nuclear Power Station Unit 1 Date of Occurrence: May 10, 1983 Enclosed are three copies of Licensee Event Report 83-023 which are being submitted in accordance with Technical Specification 6.9 to provide 30 day written notification of the subject occurrence.

Yours truly,

/Q D G]-

Terry D. Murray Station Superintendent Davis-Besse Nuclear Power Station TDM/ljk Enclosures cc: Mr. Richard DeYoung, Director Office of Inspection and Enforcement Encl: 30 copies Mr. Norman Haller, Director Office of Management and Program Analysis Encl: 3 copies Mr. Tom Peebles NRC Resident Inspector Encl: 1 copy JUN 131983 THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO. OHIO 43652 6N Il

)

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-83-32 DATE OF EVENT: May 10, 1983 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Loss of 120 VAC Escential Bus Y4 Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT)

= 2498 and Load (Gross MWE) = 835. ,

Description of Occurrence: On May 10, 1983, at 1026 hours0.0119 days <br />0.285 hours <br />0.0017 weeks <br />3.90393e-4 months <br />, the station experienced a loss of 120 VAC essential bus Y4. This placed the unit in the action statement of Technical Specification 3.8.2.1. As a result of the loss of Y4, the following instrumentation was de-energized: Reactor Protection System (RPS) Channel 4 (Technical Specification 3.3.1.1) and Safety Features Actuation System (SFAS) Channel 4 (Technical Specification 3.3.2.1). The loss of RPS Channel 4 coincided with testiag in Channel I resulting in an incorrect power signal to the Integrated Control System (ICS) which caused a reactor trip.

Designation of Apparent Cause of Occurrence: While perforcing modification work in the Low Voltage Switchgear Room 2, a spray can being used tipped over, and the nozzle broke off causing water to spray outo the protective plastic on the scaffolding. As a result, water and debris from the scaffolding worked its way through the protective plastic into the regulated rectifier YRF4 and caused the inverter YV4 input fuse to blow.

Analysis of Occurrence: There was no danger to the health and safety of the public or station personnel. All safety systems performed as designed.

Post trip plant response was normal.

Corrective Action: Y4 was repowered via its alternate source (YBR) at 1052 hours0.0122 days <br />0.292 hours <br />0.00174 weeks <br />4.00286e-4 months <br /> on May 10, 1983. The inverter YV4 input fuse was replaced, and Y4 was restored to its normal supply at 1336 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.08348e-4 months <br /> on May 10, 1983. This removed the unit from the action statement of Technical Specification

3.8.2.1. SFAS Channel 4 was reset at 1059 hours0.0123 days <br />0.294 hours <br />0.00175 weeks <br />4.029495e-4 months <br /> on May 10, 1983, and RPS Channel 4 was reset at 1117 hours0.0129 days <br />0.31 hours <br />0.00185 weeks <br />4.250185e-4 months <br /> on May 10, 1983.

l l All scaffolding on site was checked to ensure that proper precautions -

involving scaffolding cleanliness and construction were being observed.

Memo FM-83-914 was issued outlining extra precautions when erecting scaffolding over electrical equipment.

Failure Data: Although there have been previous losses of 120 VAC essen-tial buses none have occurred due to a similar root cause.

LFT #83-023

,