ML20042F900

LER 90-005-00:on 900411,experienced Loss of Dc Power to Portion of Div I Primary Containment Isolation Sys Logic Which Resulted in Isolation Signal & Actuation.Caused by Failure to Update Drawings & procedures.W/900504 Ltr

ML20042F900
Person / Time
Site:	LaSalle
Issue date:	05/04/1990
From:	Diederich G, Wiemholt T COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-005-05, LER-90-5-5, NUDOCS 9005100132
Download: ML20042F900 (6)

Text

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CommonweaMi Edison LaSalle Oounty Nuclear StClioa Rural Route (f. Box 220 -

Marseliles. Illinois 61341 Telephone 815/357 6761 i

a May 4,-1910 i

Director of Nuclear Reactor Regulation U.S. Nuclear Regulatory Conmission Mall Station PI-137 Washington, D.C. 20555 ,

Dear Sir:

Licensee Event Report 190-005-00, Docket 4050-374 is being submitted to your office in accordance with 10CrR50.73(a)(2)(lv).

O r7G. J. Diederich POLStation Manager LaSalle County St. tion GJD/TWW/ch Enclosure xct Nuclear Licensing Administrator NRC Resident Inspector NRC Region III Administrator ,

INPO - Records Center 9005100132 900504 gj ,

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LICEN$EE EVENT REPORT (LER) Fann _Rev 2.0.

Docket Number (2) Pane (?,)

Facil'ity N e (1)

LaSalle County Station Unit 2 01 51 01 01 01 31 71.4 .1!of 0 Title (4)

Inadrtitent Division I Isolation Due to. Loss of DC power to Isciation Looit d w to Protedural_ Error Event D ue ($1 LER Number (6) _ggoort Date (7) Other Facilities involved (B) facility Names Docket Nytnber(s) +

mom h Day Year Year ///

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// Number // Number 0151010101 1 I 01 4 11 1 91 0 91 0

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0l0 015 01 4 . 91 0 01 51 01 01 01 l l THIS REPORT 15 $UBMITTED PUR$UANT TO THE REQUIREMENTS OF 10CFR OPERMIE (Check one or more of the followinal (11) 20.402(b) 20.405(c) _L 50.73(a)(2)(iv) _ 73.71(b)

POWER 20.405(6)(1)(1) __ 50.36(c)(1) __ 50.73(a)(2)(v) _._ 73.71(c)

Ltytt 20.405(a)(1)(ii) 50.36(c)(2) 50.73(e)(2)(vii) _

Other ($secify 0!0!O (101 20.405(a)(1)(lii) __ 50.73(a)(2)(1) _ 50.73(a)(2)(vill)(A) in Abstr'act

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

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Name TELEPHONE NVteER AREA CODE Terrv W. Wiemholt. Technical Staf f Enoineer. Extention 2319 8l1l5 31 El 71 l 61 71 61 COMPLETE ONE LINE FOR EACH COM ON N FAILURE DESCRIBED IN TH1$_REPjRT (13)

REPORTABLE CAUSE $Y$ TEM COMPONENT MANUFAC- REPORTABLE CAU$E SY$ TEM COMPONENT MANUFAC.

TO NpRDS_ TURER TO NPRDS TURER D 31M i l I l l l N l l l l l l l I I I I I i i 1 1 I l _1 1 I SUPPLEMENTAL REPORT EXPECTED (14) Expected Month l Day l Year

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AB$iRACT (Limit to 1400 spaces, i.e. approximately fif teen single-space typewritten lines) (16)

On April 11, 1990 at approximately 0016 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> with Unit 2 defueled at 0 percent power, while hanging Out Of Service (005) 2 538-90 in preparation for Unit 2 Reactor Core Isolation Cooling (RI) work, circuit breaker (CB) #7 at 125VDC Panel 211Y was opened per ths 00$ checklist. This resulted in a loss of DC power to a portion of the Division I Primary Containment Isolation System (PC) logic, resulting in a Division I isolation signal and actuation.

Upon investigation, it was determined that CB #7 at Panel 2HY supplied power to the DC powered portion of the Olvision ! PC logic only, and not the RI system.

The apparent root cause of this event was f ailing to correctly update all drawings and procedures resulting from an equipment change during initial construction.

This event is reportable to the NRC pursuant to the requirements of 10CFR50.73(a)(2)(iv) due to the actuation Gf an Engineered Safety Feature ([$F) System.

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Lahlh_Lounty Stalinn_ Unit 2 0Is101010131714 91 0 - 0l015 - Ol0 01 2 0F OM I

TEXT Energy Industry identification System (t!!$) codes are identified in the text as (XX)

PLANT AND $Y$1EM IDENT!f! CATION General Electric - Bolling Water Reactor Energy Industry identification System (E!!$) codes are identified in the text as (XX).

A. CONDillDN PRIOR TO EVENT Unit (s): _.l_ Event Datet 4-)h30 Event Time: ,J016 Hours-Reactor Mode (s): Qthteltd Mode (s) Name: D.tlytled Power Level (s): ,_QL B. DESCRIPi!ON Or EVENT On April 11,190'. St approximately 0016 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> with Unit 2 defueled at 0 percent power, while hanging Out Of Service (PG , >$38-90 in preparation for Unit 2 Reactor Core Isolation Cooling (RI) (BN) work, circuit bre: 10 #7 at 12$VDC Panel 211Y was opened per the 00$ checklist. This resulted in a loss of DC power y partion of the Division I Primary Containment Isolation System (PC) (JM) logic, resulting in a D! vision I isolation signal to perf orm the following:

- Close the outboard isolation velves f or Groups 11, IV, V. VI, VII, and X.

- Close the outboard isolation valves for the Main Steam Line Drains.

- Actuate half of the isolation logic f or the Main Steam Line Isolation Valves.

- Initiate the Division i Post-LOCA H2-02 monitor and both Standby Gas Treatment $ystems.

Only the "A" loop Primary Containment Chilled Water System (VP) [KM) outboard isolation valves (2VP0$3A and 2VP063A) and the Reactor Dullding Closed Cooling Water $ystem (WR) (CC) outboard isolation valve (2WR029) (Group !!) went closed, because all of the other valves were already closed. A Group IV isolation was not received due to Temporary System Change (TSC) 2-251-90 which overrode all Group IV

!solations not required for this plant condition.

While reviewing the 00$ checklist prior to opening CD #7, the Equipment Operators had noticed that CB #7 at 12$VDC Panel 211Y was labelled "PCl$ 2PA13J". They checked the key Diagram (drawing 1E-2 4000fB) posted locally as an operator aid at Panel 211Y. This diagram indicated that CB #7 supplied both PC Panel 2PA13J and 2E51-C002 (R1 turbine). This convinced the operatore that the 00$ checklist was j correct. CD #7 was opened.

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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION form Rev 2.0 FACIL11Y NAME (1) DOCKET NUMBER (2) LER HUMBER (6) Pane (3)

Year / Sequential /// Revision

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// Number 777

/// Number _

LII611thunty.h4112n Vnit 2 015l_Q_10l0131714 91.0 _ 0l0_L_$ -

_0 1 0 .01 3 0F 01 5 TEXT Energy Industry Identificattore System (Ell $) codes are identified in the text as (XX)

Upon investigation, it was determired that CB #7 at 12$VDC Panel 211Y supplied power to the DC powered portion of the Division ! PC logic only, and not the R1 system. At about 0215 hours0.00249 days <br />0.0597 hours <br />3.554894e-4 weeks <br />8.18075e-5 months <br /> on April 11, 1990, step 1 of 00$ 2-538-90 checklist was deleted and CB #7 was closed restoring power to Division 1 PC Logic The isolation logic was reset. The "A" VP loop was restarted and the drywell WR isolation valve was reopened.

This event is reportable to the NRC pursuant 10 the requirements of 10CFR50.73(a)(2)(iv) due to the actuation of an Engineered Safety Feature (EST) System.

F C. APPARENT CAUSE OF EVENT .

The apparent root cause of this event was f ailing to cot rectly update all drawings and procedures resulting from an equipment change during initial construction.

In April of 1980 Unit 1 and Unit 2 Electrical Checklists LOP.DC-07E and LOP-DC-02E, PC system schematic drawings, and Unit 1 key diagram 1E-1-4000FB were correctly up' lated to show that CB #7 at 125VDC Panels 111Y and 211Y had been changed to be a power supply for PC Logie Panels IPA 13J and 2PA13J and no longer a supply to RI tur-bines 1E51.C002 and 2E51-C002.

LaSalle Station f ailed to update Electrical Chetklists LOP-RI-ole ct LOP-RI-02E, which, at the time of the event, sill 1 listed CB #7 at Panels 111Y and 211Y as a power supply to IE51-C002 and 2E51-C002.

Drawing IE-2 4000FD was incorrectly updated in that the reference to 2E51-C002 was not removed when the text was correctly changed from "RI turbine" to "PC logic panel 2PA13J". As a result, drawing IE-2-4000fB erroneously indicated the CB #7 at Panel 211Y supplied both PC 2PA13J 6@ 2E51-C002.

Contributing causes were:

a) 00$ 2-536-90 was written to open CB #7 on Panel 211Y as an isolation point for isolating power to the RI Turbine 2E51-C002, using a controlled document in accordance with LaSalle Administrative Procedure LAP-900-4, " Equipment Out-Of-Service Procedure". The Supervisor, who wrote the 00$

Checklist, derived the 005 Checklist step 1 from the Electrical CheckIlst LOP-RI-02E, without checking other documents to see what other equipment might be affected by the opening of the CB.

b) The Electrical Checklist LOP-RI-01E was not immediately revised to correct the incorrect reference to Panel 111Y CB #7 when the problem was first identified in June 1988. At the time of the event both LOP-RI-01E and L0p-RI-02E procedures were in revision to correct the deficiency, c) The Equipment Operators did not address their concern r. bout the discrepancy betwen the CB label and the 005 checklist to their supervisor.

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[ LIEENSEE EVENT REPORT (LER) TEXT EONTINUATION Form Rev 2.0

} LER HUteER (6) Pane (3)

! FACfLITY NANC (1) DOCKET NUtBER (2)

Year ff j//

,/j

/// Sequential //

f Revision

/ Nunher /// Numbet LaSalle Ecunty Shilon Unit 2 0 1 5 1 0 1 0 1 0 1 31 71 4 91 0 -

O_1015 - 0l0 01 4 0F 01_$

TEXT Energy Industry Identification System (EIIS) codes are identified in the text as [XX)

D. SAFETY ANALYSIS OF EVENT I

The power supplies for the PC system are arranged so that loss of one power supply cannot prevent automatic isolation when required. When DC power was de-energized to the PC system. the PC system actuated as designed to minimite the potential of any radioactive releases to the environment.

The consequences of this event were minimal since the two systems which isolated (VP and WR) are not safety related systems and were not required to be operating with Unit 2 defueled. The PC system itself was not required to be operable in the existing cefueled plant condition.

This type of work is not normally done with the Unit in Operational Condition 1 (RUN), 2 (STARTUP), or 3 (HOT SHUTDOWN). Had this event occurred in one of these conditions the following actuations would have occurred:

The outboard isolation valves for Groups !!, IV, V, VI. VII, and X would have closed. ,

The outboard icolation valves for the Main Steam Line Drains would have closed.

Half of the isolation logic for the Main Steam Line Isolation Valves would have actuated.

The Division I Post-LOCA H2-02 monitor and both Standby Gas Treatment Systems would have initiated.

These actuations, by themselves, would not have caused a scram or placed the Unit in an unsafe condition.

E. CORRECTIVE ACTIONS At about 0215 hours0.00249 days <br />0.0597 hours <br />3.554894e-4 weeks <br />8.18075e-5 months <br /> on April 11, 1990, step 1 of 005 2-538-90 checklist wae deleted and CB #7 was closed, restoring power to the DC powered portion of Division I PC logic. The isolation signal was reset. "A" VP loop was restarted and the drywell WR valves were reopened. The revisions to Electrical Checklists LOP-RI-01E and LOP-RI-02E were approved, deleting Panel 111Y CB #7 and Panel 211Y CB #7 as power supplies to the RI turbines.

Electrical Checklists LOP-DC-07E and LOP-DC-02E were reviewed and verified to correctly identify Panel 111Y CB #7 and Panel 211Y CL #7 as DC power supplies to the PC logic Panels IPA 13J and 2PA13J.

LaSalle Operating Procedure, LOP-DC-04, "125 VDC System Division I Ground Location and Isolation" was reviewed and verified to correctly identify Panel 111Y CB #7 and Panel 211Y CD #7 as DC power supplies to the PC logic l'anels IPA 13J and 2PA13J. LOP-DC-04 will be revised to add more detail to the caution statement which immediately precedes the step which opens CB #7 at panel 111Y or 211Y. Action Item Record (AIR) 374-200-90-02701 will track completion of this revision.

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.' LIEENSEE EVENT REPORT (LER) TEXT CONTIN'JATION fom Rev 2.0 FACfLITY NAME (1) 00CKIT NUMBER (2) __LER NUMBER (6) Page (3)

Year /j/jj

/ Sequential //jj

/ Revision

/// Number j/// Numben LaSalle County Station Unit 2 0 1 5 1 0 1 0 1 0 1 31 71 4 91 0 - Ol0l5 - 010 Of 5 0F 01 5 TEXT Energy Industry Identification iystem (EIIS) codes are identified in the text as [XX) pen and ink changes were made correcting the local operator aid. 1E-2-4000FB. at panel 211Y and the Circuit Directory at panel 111Y.

Drawing Change Request (DCR) #90-070 was generated to correct the error on IE-2-4000FB.

A General Information Notification (GIN) will be developed and issued to inform the appropriate operating department shift personnel on the following good practices:

a) When writing 00S's using Checklist Procedures as the primary source, a second controlled source (preferably the schematic drawing) should be referenced to prevent unknowingly de-energlaing other components powered from the same source which r.ay not be detailed in the description of the Checklist Procedure, b) When writing 005's involving DC breakers, the 005 writer should use the appropriate DC Ground Isolation procedure to ensure that no unanticipated isolations or actuations occur.

c) If any conflicting infomation is found in the plant, the personnel involved should confer with their supervisor to obtain a resolution prior to proceeding with a related evolution.

AIR 374-200-90-02702 will track completion of this GIN.

LAP-900-4, " Equipment Out-0f-Service Procedure" will be revised to incorporate practices a) and b) above. AIR 374-200-90-02701 will track completion of this revision.

Other DOS's that have been written using LOP-RI-02E as a reference were reviewed to ensure the CB #7 was not taken 005 without appropriate precautions.

All Procedure Addendum Deficiency Sheets currently in Central file, that affect Operating Department procedurrs, will be reviewed for appilcability and prioritized in accordance with LAP-200-2, " Operating Staff Implementing Procedure". AIR 374-200-90-02703 will track completion of this review.

F. PREVIOUS EVENTS LER Number Title 374/86-037-00 Spurious Group 11 and Group IV Istlation G. COMPONENT FAILURE DATA There was no component failure.

A