05000373/LER-1993-013

LER 93-013-00:on 930727,received Partial Group 7 Isolation. Caused by Failure of Coil in Relay 1B21H-K78.Work Request L23678 Written to Troubleshoot Group 7 Isolation.Subj Relay Problem Identified & Relay replaced.W/930816 Ltr

ML20056E145
Person / Time
Site:	LaSalle
Issue date:	08/16/1993
From:	Bryant J, Schmeltz J COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-93-013-02, LER-93-13-2, NUDOCS 9308200110
Download: ML20056E145 (5)

LER-2093-013,

Event date:
Report date:
3732093013R00 - NRC Website

text

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. Commonwealth Edison LaSalle County Nuclear Station 2601 N. 21st. Rd.

Marseilles, Illinois 61341 Telephone 815/357-6761 August 16, 1993 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 Licensee Event Report #93-013-00, Docket #050-373 is being submitted to your office in accordance with 10CFR50.73(a)(2)(iv).

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Acting Station Manager -

LaSalle County Station JVS/JEB/tsh Enclosure i

cc: Nuclear Licensing Administrator NRC Resident Inspector NRC Region III Administrator INPO - Records Center IDNS Resident Inspector I

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9308200110 930816 PDR ADOCK 05000373 S PDR

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• LICENSEE EVENT REPORT (LER) i Fociiity Name (1) Docket Number (2) Paae (3)  !

LaSalle County Station Unit 1 0 15 10 10 10 13 17 13 01 lofl0 l3 Title (4)

Primary Containment Isolation System Relav Failure

Event Date (5) LER Number (6) Report Date (7) Other Facilities Involved (8)  ;

Year Year ,/p/,/ Sequential //j/ Revision Year Docket Number (s)

Month Day Month Day Facility Names

/// Number g/// Number 0 15 to 10 to i l I

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0 17 2 17 9 13 9 13 0 11 13 0l0 0 18 1 16 9 13 0 15 10 10 10 I I I i THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10CFR  !

OPERAU NG

, (Check one or more of the followina) (11)  !

1 20.402(b) _ 20.405(c) J 50.73(a)(2)(iv) _ 73.71(b)

POUER _,_ 20.405(a)(1)(i) _ 50.36(c)(1) ,_ 50.73(a)(2)(v) _,,,_ 73.71(c) l

. LEVEL 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii) Other (Specify l0 l0 (10) 1

_ 20.405(a)(1)(iii) _ 50.73(a)(2)(i) _ 50.73(a)(2)(viii)(A) in Abstract  !

_ 20.405(a)(1)(iv) _ 50.73(a)(2)(ii) _ 50.73(a)(2)(viii)(B) ' below and in l

__ 20.405(a)(1)(v) _ 50.73(a)(2)(iii) _ 50.73(a)(2)(x) Text) [

LICENSEE CONTACT FOR THIS LER (12)  !

, Name TELEPHONE NUMBER  ;

AREA CODE I Jef f rev E, Bryant . Sys tem Enaineer Ext, 2319 8l 1 l5 3 15 17 1 -16 17 16 l l COMPLETE ONE LINE FOR EACH COMPO T FAILURE DESCRIBE 0 IN THIS REPORT (13) .

J CAUSE SYSTEM COMPONENT MANUFAC- REPORTABLE CAUSE SYSTEM COMPONENT MANUFAC- REPORTABLE  !

TURER TO NPRDS TURER TO NPP E f EL JlM IR IC lY I I l Y l I l l I I I i i i l l I l I / I I I l l l 1

_ SUPPLEMENTAL REPORT EXPECTED (14) Expected Month I Oav l Year f Submission  ;

Date (15) I l l lves (If ves. complete EXPECTED SUBMISSION DATE) X l NO l l l 1 l l ABSTRACT (Limit to 1400 spaces, i.e, approximately fif teen single-space typewritten lines) (16)  !

a On July 27,1993 at 2010 hours0.0233 days <br />0.558 hours <br />0.00332 weeks <br />7.64805e-4 months <br /> Unit 1 was in Operational Condition 1, Run at 100% power when a partial Group t

7 isolation was received. The isolation was the result of a failed coil in relay 1821H-K78.

The f ailed coil caused the logic associated with the K78 relay to trip, generating the partial Group 7  !

e i s ol ation. The entire Group 7 isolation was not received due to electrical separation between the Inboard l d

Isolation Logic and the Outboard Isolation Logic. '

, The safety consequences of the event were minimal. The Primary Containment Isolation System logic is I 1

nonnally energized, deenergize to actuate. When the coil f ailed, a short circuit was created which dropped I logic voltage, deenergiring the logic. j

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Work Request L23678 was written and the failed relay was replaced and successfully functionally tested.

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'g LICENSEE EVENT REPORT (LER) TEXT CONVINUATION Form Rev 2.0 FACILITY NAHE (1) DOCKET NUMBER (2) LER NUMBER (6) Pace (3)

Year / Sequential /jj/

/ Revi sion

,/j/j/

// Number f

/// Number l LaSalle County Station 0 1 5 1 0 1 0 1 0 13 17 13 9 13 -

0 11 13 -

O l0 0 12 0F 0 13 TEXT Energy Industry Identification System (EIIS) codes are identified in the text as [XX)

PLANT AND SYSTEM IDENTIFICATION:

General Electric - Boiling Water Reactor Energy Industry Identification System (EIIS) codes are identified in the text as [XX).

! A. CONDITION PRIOR TO EVENT i

Unit (s): 1 Event Date: 7/27/93 Event Time: 2010 Hours Reactor Mode (s): 1 Hode(s) Name: Run Power Level (s): 1pp% j B. DESCRIPTION OF EVENT t

On July 27,1993 at 2010 hours0.0233 days <br />0.558 hours <br />0.00332 weeks <br />7.64805e-4 months <br /> Unit 1 was in Operation Condition 1 Run, at 100% power when a partial Primary Containment Isolation System (PCIS, PC) [JM) Group 7 isolation occurred. The isolation occurred as a result of a trip in the PCIS logic caused by relay 1821H-K78. The relay suffered a coil fault I resulting in a short circuit in the isolation logic. As a result of the trip the Transversing Incore Probes (TIPS) (NR) [IG] withdrew and Residual Heat Removal (RHR) [BI) Heat Exchanger Blowdown Valves 1E12-F049A/B received an isolation signal. The TIPS were positioned at the indexer allowing them to  ;

decay after a recent TIP set. The RHR Valves were closed prior to this event and no valve movement tock  ;

pl ace . The PCIS logic was taken Out of Service for administrative control by pulling the Division 2 Group 7 f use 1821H-F28. i Work Request L23678 was generated and the relay was replaced. LaSalle Special Test, LST 93-069 was written and the relay was functionally tested satisfactorily on 7/30/93. l This event is reportable to the NRC pursuant to the requirement of 10CFR50.73 (a)(2)(iv) due to the j actuation of aa Engineered Safety Feature.

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C. APPARENT CAUSE OF EVENT  !

Relay 1B21H-K78 suffered a fault in its coil which resulted in a short circuit in the PCIS logic. This condition allowed enough current through relay 1B21H-K78 to trip relay 1B21H-K17, which exists in J parallel with the K78 relay.

l The K17 relay provides the seal in contacts for the circuit. When the fault occurred and during subsequent testing, the voltage across the K17 relay would drop as current was drawn through the K78.

When the K17 deenergized the seal in contact would open and power to the K17 and K78 was interrupted.  ;

This seal in contact acted as a circuit breaker and kept the K78 relay from totally burning out. This l was discovered by depressing and holding the isolation reset pushbutton whose associated normally open contacts exist in parallel with the K17 seal in contact.

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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Form Rev 2.0 FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) Pace (3)

Year /j/,/ Sequential //j/ Revision f ff

/// Number /// Number

_lasalle County Station 0l5l010l0131713 9 13 -

O ll 13 -

O l0 0 13 0F 0 13 TEXT Energy Ind;stry Identification System (EIIS) codes are identified in the text as [XX]

D. SAFETY ANALYSIS OF EVENT The safety consecuences of the event were minimal. By tripping the logic channel the K78 relay was, in i effect, providing the safety function of the PCIS. The TIPS withdrew and the RHR Heat Exchanger l Blowdown Valves received an isolation signal. This is the ist1ation function of the circuit on the l receipt of a high drywell pressure (1.69#) or Level 3 reactor water level (+12.5") signal. '

i The rest of the Group 7 isolation is provided by relays IB21H-Kl8, K60 and KX60. These relays did not  !

actuate because they are both physically and electrically separated from the K78. The K78 is f electrically Division 2, where the Kl8, K60 and KX60 are Division 1.

l E. CORRECTIVE ACTIONS l

Work Request L23678 was written to troublesh.ot the Group 7 isolation. The K78 relay problem was identified and it was replaced. LST 93-069 was written to functionally test the relay and it was performed satisf actorily on July 30, 1993. The Division 2 Group 7 isolation logic was returned to l

service 7/30/93. ,

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F. PREVIOUS EVENTS i

A search of the LER database constraining on PCIS System and relay failure was performed. No previous events of this nature could be f ound. [

I G. COMPONENT FAILURE DATA i KANUFACTURER NOMENCLATURE H0 DEL NUMBER MFG PART NUMBER

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1 l Agastat Control Relay GPI 14SC323SP001  ;

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CACSE CODES p Lost generation Reactor trip i NRC violation, level ___

^ Cost > $25,000 ESF actuation GSEP event, class ____.

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Hazard or Spill NRC reportable Tech Spec LCO

~_. Personnel injury E LER Potential or future loss Component SALP functional area __

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