05000322/LER-1987-012

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LER 87-012-01:on 870504,uplanned Actuation of ESF Occurred. Caused by Technician Loosing Footing & Accidently Hitting Outside Cover of Level Switch.Permanent Ladders & Platforms Installed at Head Tank Level Switches
ML20055C497
Person / Time
Site: Shoreham File:Long Island Lighting Company icon.png
Issue date: 05/16/1990
From: Schnaars G
LONG ISLAND LIGHTING CO.
To:
Shared Package
ML20055C491 List:
References
LER-87-012, LER-87-12, NUDOCS 9005240072
Download: ML20055C497 (4)
v • d • e


LER-2087-012,
Event date:
Report date:
3222087012R00 - NRC Website
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text

_ . . .

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OOCKti NUM01R 121 FA03 4 7 ACILITY NAME 01 Shoreham Nuc] ear Power Station Unit 1 o 16 l 010 l 01317 l 3 1 loFl n 13 7'T'8 **l RBCLCW unplanned automatic system-split while Instrument & Controls Technicians were perfonning a Surveillanm Test EVENT DAff tel LER NUMSIR (6 AtPORT DATE (76 OTHEfl F ACILITitt INVOLVED let MONTM OAY YEAR YEAR " OM ,

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N1Mt TELEDMONE NUM9tR Amt A CODE George D.-Schnaars, Operational Compliance Encineer l l l l l 1 1 1 l COMPLETE ONE LINE FOR S ACM COMPONENT F ALLURE DESCRitt0 IN TMit REPORT H3i U AC yo PR'

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On May 4, 198? at 1548, an unplanned actuation of an Engineered Safety Feature occurred. The plant was in Operational Condition 4 with the mode switch in Shutdown and all rods inserted in the core.

While Instrument & Controls technicians were performing a surveillance test of the Reactor Building Closed Loop Cooling Water (RBCLCW) head tank level switches, a technician lost his footing and accidentally hit the outside cover of a level switch. This caused the level switch to change state which resulted in a RBCLCW system split. Operators verified the signal as false and . .

imrediately took the appropriate action to return the system to its rormal configuration. Plant Management was notified of the event and the NRC was notified at 1652 per 10CFR50.72. Corrective actions

-included installing permanent ladders and platforms at the head tank level switches. This provides easier access to the switches ~and greatly reduces the risk of technicians losing their footing while Performing surveillance tests. This Supplemental Report is being submitted to inform the Commission of the status of corrective actions taken, m gooM 6 5 hl 050%f, NGC Form 366 46491 h

y 5 Xt11ES- 4/300 r LICENSEE EVENT REPORT (LER) 5 f,6"#Mo'fs'MWoi;'!;%"v ',Tio.c?T,7,T"Je's j TEXT CONTINUATION cN n'",'o'di$ig"oi'yl#',"d"c'n,'N M u '"!$ "n l PAPf RWD K Rt TION t'3 to  ! I - i Of MANAGEMENT AND DVDGET,wAsMINGTON.DC 30603.

PACILITv esAMg up DOCKET NUMBER (31 PA06 (31 LIR NUMBER ($1 Y'A" ' NMn -

NNaN Shoreham Nuclear power Station Unit 1

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n 11 nl9 OF nb Tax m . . me w maunn FLANT AND_ SYSTEM IDENTIFICATION Ganeral Electric - Boiling Water Reactor Energy Industry Identification System (EIIS) codes are identified

in the' text as [xx).

IDENTIFICATION OF THE EVENT f

Raactor Building Closed Loop Cooling Water (RBCLCW) [CC) unplanned automatic system split while Instrument & Controls (I&C) technicians were performing a surveillance test.

Event Date: 5/4/87-r l'

Raport Date: 5/16/90 l CQNDITIONS PRIQB TO THE EVENT Operational Condition 4 (Cold Shutdown) '

Mode Switch - Shutdown RPV Pressure = 0 psig

~

RPV Temperature = 170 Degrees F I All-rods inserted in the core.

DESCBIEI1QN OF THE EYENT l

On May 4,=1987 at 1548 an unplanned automatic Reactor Building Closed Loop Cooling Water (RBCLCW) system split occurred while Instrument & Controls (I&C) technicians were performing surveillance tost:SP' 44.118.03 (RBCLCW Head-Tank Level Low-Low Channel Functional Test).- An I&C technician was climbing up to the head tank level . ,

switches.to perform a step in the procedure when he.~ accidentally hit -

l the'outside' cover of level switch'1P42*LS013B causing the switch to i change state. .This caused a faise low-low "B" RBCLCW head tank

~ level signal resulting in a system split. The RBCLCW system split into two separate and independent loops "A" and "B", shedding nonessential loads as designed in' response to the low-low tank level l- L signal .- Operators verified the signal as false and immediately returned the-system to its normal configuration. Plant Management was notified of the event and the NRC was notified at 1652 per 10CFR50.72.

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Shoreham Nuclear power Station Unit 1 I I

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01 1 0 13 0 14 text w . - m . w. .e m ,w w eF ,aav. m CAUSE OF THE EVENT Level switch 1P42*LSO13B is located adjacent to the "B" RBCLCW head  !

tank in the reactor Building, approximately 20 feet abeve the floor l of elevation 150 ft. By procedure, it is required that the leve) '

switch identification tag numbers be checked to verify that the proper level switch will be tested during subsequent steps in the  !

procedure. The identification tags are located on the outside of ,

the level switches. The level switches are out of normal reach. An  !

Instrument & Controls (I&C) technician was climbing into position to i read an identification tag when he accidentally hit level switch l i

1P42*LS013B. While holding a flashlight in one hand, and holding

  • onto a pipe with the other hand, the technician lost his footing and  ;

accidentally hit the outside cover of 1P42*LS013B with the flashlight, i' This action caused the switch to change state. This resulted in a false low-low "B" RBCLCW head tank level signal resulting in a ,

RBCLCW system split whereby nonessential loads were shed as i i

designed. The technicians were adequately trained and qualified to perform their required tasks. l The root cause of the problem was the poor accessibility of the l level-switches. A contributing factor may be oversensitivity of the level switch. It should be noted that in November of 1985, a -

Station Modification (SM #85-064) replaced and upgraded several ,

parts in the-RBCLCW head tank level switches in order to ensure Environmental- Qualification. A review of the Environmental Qualification Report reveals that switch contact chatter was noted during seismic testing of the rebuilt level switches. This undesirable characteristic was accepted since " spurious operation of the switch can only cause the associated control circuit to assume its " fail safe" operating position".

ANALYSIS.SE_lHE EVENT ,

This event was an unplanned actuation of an Engineered Safety Feature (ESF). There was no safety significance to the event. The RBCLCW system operated as designed by splitting into two independent loops and was capable of performing its safety function. Had the event occurred under a more severe set of circumstances (5% power) there would still be no safety significance.

CORRECTIVE ACTIQHS

1. An investigative plan was developed to determine the need to modify or replace the RBCLCW head tank level switches to reduce sensitivity. Implementation of this plan has been deferred indefinitely due to the New York State-LILCO Shoreham Settlement Agreement.

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' Shoreham Nuclear power Station Unit 1 .

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011 014 OF n ja rixv in N w. we i asuw mi 2.- Permanent ladders and platforms have been installed at the head tank level switches to provide easier access.

3. Identification tags were installed on the level switch piping m assemblies where they may be reached more easily than the tags that were' installed on the level switches. ~The necessary l verifications are now made by reading'the tags at the more accessible locationn which will reduce the possibility of disturbing the level switches. The appropriate procedure-changes were also made.
4. Caution statements were added to appropriate places in Station l Procedure 44.118.03 "RBCLCW Head Tank Level Low-Low Channel Functional Test" to caution technicians of the sensitivity of the level switches.
5. A report describing the incident was read by all Instrument &

Controls (I&C) technicians.

ADDITIQHAL_INFORMATION

a. Manufacturer and model numbgr_2f_ failed SQmponent_Lal None
b. LEB_ numbers _.of_ previous similar_ events

,86-008 (Event date 2/14/86)

L l 86-024 (Ev'ent date 5/22/86) l 6

l .', '

l l'

NIC Penn 306A 16491

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