ML20135E964

Special Rept SR-96-003-00:on 961027,valve & Loose Parts Monitoring Sys Declared Inoperable.Caused by Failure of Sensor on Channel 1.Sensor Will Be Replaced During Refueling Outage 8

ML20135E964
Person / Time
Site:	Waterford
Issue date:	12/10/1996
From:	Dugger C ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
SR-96-003-00, SR-96-3, W3F1-96-0212, W3F1-96-212, NUDOCS 9612120263
Download: ML20135E964 (5)

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Ent:rgy Oper: tion 2, Inc.

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Po. Box B i

Killona. LA 70066 Tel 504 464-3120 j

Charles M. Dugger General Manager Plant Operations t

Waterford 3 W3F1-96-0212 i

A4.05 i

PR December 10,1996 U.S. Nuclear Regulatory Commission

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Attn: Document Control Desk Washington, D.C. 20555

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Subject:

Waterford 3 SES Docket No. 50-382 License No. NPF-38 Reporting of Special Report Gentlemen:

Attached is Special Report Number SR-96-003-00 for Waterford Steam Electric Station Unit 3. This report provides details of a condition in which Channel 1 (A and B) of the Valve and Loose Pads Monitoring System is inoperable for more than 30 days. The most probable cause of this condition is normal wear of sensors that are located on the bottom of the reactor vessel. This Special Report is submitted in accordance with Technical Requirements Manual 3.3.3.9, Loose-Part Detection Instrumentation, Action a.

Very truly yours, I

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V, C.M. Dugger -

J General Manager Plant Operations CMD/WDM/tjs Attachment 9612120263 961210 PDR ADOCK 05000302 S

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Reporting of Special Report (96-003-00)

W3F1-96-0212 i

Page 2 December 10,1996 cc:

L.J. Callan, NRC Region IV C.P. Patel, NRC-NRR A.L. Garibaldi

'J.T. Wheelock - INPO Records Center i

R.B. McGehee N.S. Reynolds NRC Resident inspectors Office Administrator - LRPD i

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SPECIAL REPORT SR-96-003-00 SEPORTABLE OCCURRENCE Technical Requirements Manual (TRM) Limiting Condition for Operation (LCO) 3.3.3.9, Loose-Part Detection Instrumentation, Action a states, "With one or more loose-part j

detection system channels inoperable for more than 30 days, prepare and submit a Special Report to the Commission pursuant to Specification 6.9.2 within the next 10 days outlining the cause of the malfunction and the plans for restoring the channel (s) to 1

OPERABLE status." This report is being submitted due to channel 1 (A and B) being inoperable greater than 30 days as of November 30,1996.

4 INITIAL CONDITIONS At the time this event occurred, Waterford was operating in Operations Mode 1 at approximately 100% power. There was no major equipment out of service specific to this event and no Technical Specification (TS) LCO's were in effect specific to this event.

EVENT DESCRIPTION On October 27,1996, at 0755 hours0.00874 days <br />0.21 hours <br />0.00125 weeks <br />2.872775e-4 months <br />, the Valve and Loose Parts Monitoring System (VLPMS) annunciator alarmed in the Control Room. The operator observed that the 2

VLPMS was calculating a bad start time every 30 seconds. The operator attempted to reboot the system twice wi+hout success. The system lost its CRT display and would not respond to input. The VLPMS computer was declared inoperable which renders the Loose Parts detection inoperable. TRM LCO 3.3.3.9a was entered at 0755 hours0.00874 days <br />0.21 hours <br />0.00125 weeks <br />2.872775e-4 months <br />. The computer failure did not prevent audible monitoring of the valve monitoring channels.

During troubleshooting efforts, the computer was successfully rebooted and returned to normal. The Control Room staff successfully completed surveillances OP-903-122,

" Valve and Loose Parts Monitoring System Channel Functional Test," and OP-903-013,

" Monthly Channel Checks," Section 10.3 and declared VLPMS operable at 1451 hours0.0168 days <br />0.403 hours <br />0.0024 weeks <br />5.521055e-4 months <br /> on October 29,1996. Intermittent alarms continued to occur and upon further review, the event was determined to be attributed to sensor failures on channel 1 that were causing continuous alarms and sporadic signals to be processed by VLPMS. This constant input of spurious information caused the computer impact buffer to overflow which caused the subsequent computer lockup. Channels 1 A and 1B were declared inoperable on October 31,1996, at 0945 hours0.0109 days <br />0.263 hours <br />0.00156 weeks <br />3.595725e-4 months <br /> and deactivated to prevent the spurious alarms. Because the failed channels are located on the lower portion of the reactor vessel, replacement will take place during Refueling Outage 8 (RF8) which is scheduled to begin April 11,1996.

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v CAUSAL FACTORS l

l The sensors on channel 1 (A and B) had an apparent failure which caused a high amount of spurious alarms that locked up the VLPMS computer system. The sensors that failed are located on the lower portion of the reactor vessel. In this location they ~

are. subjected to high radiation, temperature, and humidity levels. Inspections conducted in October of 1995 determined that the connectors for the sensors in l

question were slightly deteriorated. However, replacement parts could not be obtained l

prior to the end of the outage. The existing equipment was cleaned and the channel l

was tested and determined to be operable during the normal 18 month system

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surveillance. The exact cause of the failure will be determined when the sensors are inspected during RF8. At that time Waterford 3 will submit a follow-up report detailing j

the findings.

CORRECTIVE MEASURES Channels 1 A and 1B were deactivated which cleared the spurious alarms and allowed i

normal processing of the computer impact buffer inputs. These sensors, along with the applicable hardware, are scheduled to be replaced during RF8.

j SAFETY SIGNIFICANCE l

l The VLPMS is provided to monitor the Reactor Coolant System (RCS) for loose parts in the reactor internals. The system consists of sixteen high-temperature sensor j

assemblies (eight in Train A and eight in Train B), independent preamplifiers with shielded enclosures, system mounting and wiring hardware, and one signal processing l

and monitoring cabinet. Each detector module will monitor either channel A or B sensors via a toggle switch in the cabinet. Contact outputs which open on alarm for loose parts detected are provided as interface to the main plant annunciator.

l With the channel 1 sensors inoperable, seven loose part detector channels and four core internals channeis are available to detect loose parts in the RCS. Regulatory Guide 1.133, Loose-Part Detection Program for the Primary System of Light-Water-Cooled Reactors, states that if all channels of one or more collection regions are inoperable for more than 30 days, the reactor need not be shutdown, but a special report should be prepared and submitted to the Commission within the next 10 days outlining the cause of the malfunction and the plans for restoring the channel (s) to an l

operable status, in NRC letter ILN 95-0095 dated April 20,1995, concerning issuance of Amendment 104 to the Waterford 3 TS, the commission stated that they believe this i

type of reporting requirement is adequately covered by other regulations under 10CFR50.72 and 10CFR50.73. The staff concludes that the loose-part monitoring system requirements are not required to obviate the possibility of an abnormal situation or event giving rise to an immediate threat to the public health and safety.

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Based on this information, this condition does not compromise the health and safety of j

the public or plant personnel.

SIMILAR EVENTS None i

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