ML20043B574

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LER 90-009-00:on 900427,discovered That Moving Filter Paper in Leak Detection Sys Drywell Air Particulate Sample Panel Not Collecting on take-up Reel.Caused by Loose Set Screw on Gear Train.Set Screw tightened.W/900521 Ltr
ML20043B574
Person / Time
Site: Clinton Constellation icon.png
Issue date: 05/21/1990
From: Rasor S, Spangenberg F
ILLINOIS POWER CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-009, LER-90-9, U-601674, NUDOCS 9005300239
Download: ML20043B574 (6)
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20.220 CLINTON POWER STATION. P.O. DOX 678, CLINTON, ILLINOIS 61727 0678, TELEPilONE (217) 935 8881, j F May 21,;1990 10CFR50.~73 Docket No~.50 461 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. . 20555

Subject:

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Clinton Power Station - Unit 1 Licensee Event Reoort No. 90-009-00

Dear Sir:

Please find enclosed Licensee Event Report No.- 90 009 00: Loose' Set.

Screw on Cear Train of Moving Filter Paner Drive Mechanism Results in Paner=

Not Movine and Inonerable Leak Detection Drywell Air Particulate Samnle Panel, This report is being submitted in accordance with the requirements of

-100FR50.73.

Sincerely yours,

( .

F.A.Sphngenb g, II Manager - Licensing and Safety RSF/ cam s

Enclosure

? cc: NRC Resident Office d NRC Region III, Regional Administrator m IUPO Records Center Illinois Department of Nuclear Safety NRC Clinton Licensing Project Manager 1

I 9003300239 900521 DR ADOCK 0500 1 gQg ip

i W C Form 3e4 U 5 NUCLEAR MOULATDM COMMISSION APPROVED OMB NO 3 % 0 0104 LICENSEE EVENT REPORT (LER) " a ' 5 ' ' 3""

f ACILITV NAME 01 DOCR E T NUM8t R (2) > AGE s3' Clinton Power Station 0j5jojolol4]6l1 1 loFl015 mms's Set Screw on Gear Train of Moving Filter Paper Drive Mechanism Results in Paper Not Movinn and Inoperable Leak Detection Drywell Air Particulate Sample Panel t ytNT DATE (61 LER NUM3g R 16) REPORT DATE (71 OTHE R 8 ACILITIES INVOLVED 18)

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20 406teH1 Hel 60 73tell2 Hoe) 60 736eH2Her LICENsEt CONT ACT FOR THis LE R H21 N AMt ' T E LEPHONE NUMBER ANE A CODE S. E. Rasor, Director - Plant Maintenance, extension 3204 2l1l7 9l3 i51 1 8l 8 811 1 COMPLE TE ONE LINE FOR E ACH COMPONE Nv F AiLURE OfSCRl3E D IN THis REPOR T 113i

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On April 27 1990, with the plant in Mode 1 (POWER OPERATION) a technician discovered the moving filter paper in the Leak Detection system drywell air particulate sample panel lE31-P002 was not collecting on the take-up reel. The Shift Supervisor was notified of this and he declared the panel inoperable. He also directed the drywell atmosphere be manually sampled and analyzed at least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The length of time the filter paper had not been moving could not be determined.

This condition was determined to be prohibited by Technical Specification 3.4.3.1. Troubleshooting of 1E31-P002 identified a loose set screw on the normal speed gear train of the filter paper drive mechanism as the cause of this event. The loose screw had allowed one gear to slip out of aligrunent resulting in insufficient gear engagement. Corrective actions included realigning the gear; tightening the set screw; verifying proper filter paper movement; revising a preventive maintenance task to require inspection of the gear assembly for proper gear engagement and set screw tightness, and provide better dira tion on verifying proper filter paper movement; and investigating methods to ensure proper operation of the filter paper drive mechanism without requiring disassembly of the sample pane 1.

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EXPsRES: t/31/M f ACitiTV hAME Hi DoCE8T NUMet A ul Lt A NUMeER I6I PACE (31 vaan .

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0l0 0l2 OF 0 l5 l rurrn . w waner mconn DESCRIPTION OF EVENT-  ;

On April 27, 1990, a Control and Instrumentation:(C61) technician .

discovered the moving filter _[FLT) paper in Leak Detection (LD) system 1

-[IJ) .drywell air particulato sample panel-[PL) 1E31-P002 was not '

collecting on the take up reel'and therefore the panel was inoperable.

This condition was determined to be prohibited by Technical Specifivation 3.4.3.1 which requires the drywell atmosphere particulate radioactivity ,

monitoring system, the drywell sump flow monitoring system, and either the drywell atmosphere gaseous radioactivity monitoring system or the drywell air coolers condensate flow rate monitoring system to be' operable in Modes 1 (POWER OPERATION), 2 (STARTUP) and 3 (HOT SHUTDOWN),

On April 4, 1990, with the plant in Mode 4 (COLD SHUTDOWN), a C61 technician performed' Preventive Maintenance (PM) task PCILDW001 on 1E31 P002. This PM task requires replacement of the sample panel's- 'E moving-filter paper at approximately two week intervals. The technician verified the fil_ter paper was moving properly following replacement and then de energized the panel since it.was not required to be operable in ,

-Mode 4.

l: The sample panel monitors air particulate of the drywellLfor.-

radioactivity. The panel does this by receiving-a reprnsentative sample

!? of gaseous and effluent particulates from the drywell and trapping the l

particulate matter on moving filter paper. The filter paper is designed to retain the particulates and is passed in front of a scintillation detector [DET) where any radioactivity is detected. The panel provides-continuous indication and activates alarms in the Main Control Room.

l On April 7, 1990, at approximately 1537 hours0.0178 days <br />0.427 hours <br />0.00254 weeks <br />5.848285e-4 months <br />, the plant entered Mode 2 l and in accordance with the Mode 2 startup checklist 1E31-P002 was a energized.

On April 10, 1990, at approximately 1825 hours0.0211 days <br />0.507 hours <br />0.00302 weeks <br />6.944125e-4 months <br />, the plant entered Mode 1.

On April 13, 1990, unrelated to this event, the Vice President directed g the plant be shut down. This shutdown is discussed in LER 90-008-00.

l On April 15, 1990, at approximately 0545 hours0.00631 days <br />0.151 hours <br />9.011243e-4 weeks <br />2.073725e-4 months <br />, the plant entered Mode 4 l' and lE31-P002 was not required to be operable.

On April 18, 1990, with the plant in Mode 4, C61.again per' formed PM task PCILDW001 on lE31 P002. At this time, the sample panel was de-energized L

for performance of the PM task. The technician did not replace the filter paper during this task because he noted the take-up reel had not ,

collected any filter paper and the roll of filter paper on the feed spool was almost full. At this point the technician did not question the

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< -unc w.mn p operability.of the sample panel since-it was found in a de energized.

status and was not required to.be operable. I On April 22, 1990, at approximately 1850 hours0.0214 days <br />0.514 hours <br />0.00306 weeks <br />7.03925e-4 months <br />, the plant entered Mode 2, and 1E31-P002 was again energized in accordance with the Mode 2 startup- ,

checklist.

On April 27, 1990, at approximately 1330 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.06065e-4 months <br />, with the plant in Mode 1 at approximately seventy percent power, while again per' forming PM task PCILDW001, the C&I technician noted the filter paper had not moved since the last performance of PCILDWOO1 on April 18, 1990 In response to this finding, the technician immediately informed his supervisor of the filter paper movement problem. The supervisor notified the Shift Supervisor

.(SS) of the problem at 1400 hours0.0162 days <br />0.389 hours <br />0.00231 weeks <br />5.327e-4 months <br />.

In response to the notification, the SS declared 1E31-P002 inoperable and' directed the drywell atmosphere be manually sampled and analyzed at least ,

once per twenty-four hours in accordance with the. ACTION of Technical Specification 3.4.3'.1. The SS further directed the PM task be completed

.and proper operation of'the filter paper be ensured prior to closing the panel.

L The technician completed the PM task and verified proper filter paper L movement.by. momentarily operating the paper drive mechanism in fast speed ,

l to ensure proper take up on the take-up reel. The technician then I

shifted the drive mechanism to normal (slow) speed and marked the paper.

Approximately six hours later, a C&I technician again verified proper filter paper movement by noting the mark on the paper and the distance l the paper had moved. (The filter paper drive mechanism consists of two l motors mounted side by side in a single housing. Each motor advances the L filter paper.at a different speed. The paper moves approximately 1.5 ,

inches per hour in normal speed and approximately 6 inches per minute in j fast speed.)

No automatic or manually initiated safety system responses were necessary to place the plant in a safe and stable condition. No other equipment or components were inoperable at the start of this event such that their inoperable condition contributed to this event, i

CAUSE OF EVENT The cause of this event is attributed to equipment failure.

Maintenance Work Request (HWR) D15183 was initiated on April 30, 1990, to investigate 1E31-P002 and determine if a mechanical failure had caused the filter paper drive mechanism.to fail. On May 1, 1990, 22,'*"" ~~ .o m i. ..um.4.

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troubleshooting in accordance with the MWR identified a loose set screw on the normal speed gear train of the filter paper drive mechanism had allowed'one gear to slip-out of alignment on its shaft.' This resulted in an insufficient amount of gear engagement to ensure-continuous, reliable ,

operation of the normal speed gear drive assembly, t CORRECTIVE ACTION .I The gear that had slipped out of alignment was realigned and the set ,

screw was tightened. The filter paper drive mechanism war reassembled and filter paper was replaced in accordance with PM task PCILDW001.

Proper paper movement was verified at both. normal and fast speeds and the

-sample panel was restored at 2159 hours0.025 days <br />0.6 hours <br />0.00357 weeks <br />8.214995e-4 months <br /> on May 3, 1990.

PM task PCILDW001 has.been revised to require inspection of the gear assembly for proper gear engagement and tightness of set screws, and to provide better direction on verifying proper filter paper movement.

As currently configured, the sample panel must be partially disassembled p to verify filter paper is moving properly. For this reason, -II will-investigate methods to ensure proper operation of the filter paper drive mechanism without requiring disassembly of the sample panel. This investigation is scheduled to be completed by August 31, 1990.

ANALYSIS OF EVENT  ;

This event is reportable under the provisions of .10CFR50.73(a)(2)(1)(B)  ;

because the plant was operated in a condition prohibited by Technical j Specification 3.4.3.1.

The length of time the filter paper had not been moving cannot be determined, however, the amount of filter paper on the take-up reel  ;

provides sufficient indication that the sample panel had been inoperable during some of the times when it was required to be operable. These times were April 7, 1990 at 1537 hours0.0178 days <br />0.427 hours <br />0.00254 weeks <br />5.848285e-4 months <br /> until April'15, 1990 at 0545 hours0.00631 days <br />0.151 hours <br />9.011243e-4 weeks <br />2.073725e-4 months <br />, and April 22, 1990 at 1850 hours0.0214 days <br />0.514 hours <br />0.00306 weeks <br />7.03925e-4 months <br /> until' April 27, 1990 at 1400 )

hours when the SS was notified of the condition and he directed drywell atmosphere be manually sampled and analyzed at least once per twenty-four hours.

The sample panel was restored to operable status at 2159 hours0.025 days <br />0.6 hours <br />0.00357 weeks <br />8.214995e-4 months <br /> on May 3, 1990.

Analysis of the safety consequences and implications of this event indicates this event was not nuclear safety significant. At the time of the event, other instrumentation was available and operable to provide both continuous indication and activate alarms in the Main Fonu seaa e U S.0Po'1986 0 624 636/455

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0l 0 0l5 0F 015 1 xt 4, m = nac s m.w nn Control Room (MCR) if-unidentified reactor coolant leakage had exceeded specified limits, This instrumentation included the drywell air cooler condensate flow rate monitoring system, drywell atmosphere gaseous radioactivity monitoring system and the drywell sump flow monitoring system. During this event.there was no unidentified leakage.

ADDITIONAL INFORMATION Drywell fission products monitor lE31-P002 is model number 133D9025G manufactured by General Electric.

No LERs have been initiated at Clinton Power Stc tion fcr similar events, For further information regarding this event', contact S. E. Rasor, Director - Plant Maintenance, at (217) 935 8881, extension.3204, s

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