NRC 2005-0119, Post Accident Monitoring Instrumentation Report

Post Accident Monitoring Instrumentation Report

ML052630363
Person / Time
Site:	Point Beach
Issue date:	09/16/2005
From:	Koehl D Nuclear Management Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NRC 2005-0119
Download: ML052630363 (3)

Text

NMCA Committed to Nuclear Excellence Point Beach Nuclear Plant Operated by Nuclear Management Company, LLC September 16, 2005 NRC 2005-0119 10 CFR 50.36 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Unit 1 Docket 50-266 License No. DPR-24 Post Accident Monitoring Instrumentation Report Point Beach Nuclear Plant (PBNP) Technical Specification (TS) 5.6.6 states, 'When a report is required by Condition B or F of LCO 3.3.3, 'Post Accident Monitoring (PAM)

Instrumentation,' a report shall be submitted within the following 14 days. The report shall outline the preplanned alternate method of monitoring, the cause of the inoperability, and the plans and schedule for restoring the instrumentation channels of the Function to OPERABLE status."

On August 7, 2005, one required channel of Reactor Coolant System Cold Leg Temperature (Wide Range) PAM instrumentation became inoperable and was not restored within 30 days, necessitating a report per Condition B of LCO 3.3.3. The attachment to this letter contains the required report of this condition.

This letter contains no new commitments and no revisions to existing commitments.

Please contact Jeff Helbing of my staff at (920) 755-6414 with any questions.

Dennis L. Koehl Site Vice-President, Point Beach Nuclear Plant Nuclear Management Company, LLC Enclosure cc: Administrator, Region ll, USNRC Project Manager, Point Beach Nuclear Plant, USNRC AUQI Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW 6590 Nuclear Road

• Two Rivers, Wisconsin 54241 Telephone: 920.755.2321

ENCLOSURE I POST ACCIDENT MONITORING INSTRUMENTATION REPORT TECHNICAL SPECIFICATION 5.6.6 POINT BEACH NUCLEAR PLANT, UNIT 1

Background

The primary purpose of the PAM instrumentation is to display unit variables that provide information required by the control room operators during accident situations. This information provides the necessary support for the operator to take the manual actions for which no automatic control is provided and that are required for safety systems to accomplish their safety functions for Design Basis Accidents (DBAs).

The operability of the accident monitoring instrumentation ensures that there is sufficient information available on selected unit parameters to monitor and assess unit status and behavior following an accident. Point Beach Nuclear Plant (PBNP) Technical Specification (TS) LCO 3.3.3 requires two operable channels for most functions. Two operable channels ensure no single failure prevents operators from getting information necessary to determine the safety status of the unit, and to bring the unit to and maintain it in a safe condition following an accident.

Function 3 of TS Table 3.3.3-1 is Reactor Coolant System (RCS) Hot and Cold Leg Temperatures (Wide Range). RCS Hot and Cold Leg Temperatures (Wide Range) are Category I variables provided for verification of core cooling and long term surveillance.

RCS hot and cold leg temperatures are used to determine RCS subcooling margin and verify adequate core cooling. RCS subcooling margin will allow termination of safety injection (SI), if still in progress, or reinitiation of SI if it has been stopped. RCS subcooling margin is also used for unit stabilization and cooldown control.

In addition, RCS cold leg temperature is used in conjunction with RCS hot leg temperature to verify the unit conditions necessary to establish natural circulation in the RCS.

Temperature inputs are provided by two independent temperature resistance elements and associated transmitters in each loop. The channels provide indication over a range of 50° F to 750° F.

Condition Description On August 7, 2005, Unit 1 "A" cold leg wide range temperature indicator 1TI-451C was declared inoperable due to erratic signals being provided from its associated sensing element (1TE-451 C). Troubleshooting and repair attempts were unsuccessful in Page 1 of 2

I .,

restoring the indicator to service. On September 6, 2005, continued inoperability of this channel of PAM instrumentation necessitated a report per Condition B of LCO 3.3.3.

TS 5.6.6 states, 'When a report is required by Condition B or F of LCO 3.3.3, 'Post Accident Monitoring (PAM) Instrumentation,' a report shall be submitted within the following 14 days. The report shall outline the preplanned alternate method of monitoring, the cause of the inoperability, and the plans and schedule for restoring the instrumentation channels of the Function to OPERABLE status."

Preplanned Alternate Method Of Monitoring Temperature elements 1TE-451A and 1TE-451C (and their associated instrument loops) are the two channels designated to meet the requirements of function 3 of TS Table 3.3.3-1 for "A" RCS cold leg temperature (wide range) monitoring. 1TE-451A and its associated instrument loop remain operable and will continue to be used to monitor UA" RCS cold leg temperature (wide range). UA" RCS hot leg, UB" hot and cold leg temperature (wide range) indicators and core exit thermal couples will also be used to determine RCS subcooling margin and verify adequate core cooling.

Cause Of The Inoperability Temperature Indicator 1TI-451C was observed to be reading low, as indicated on the plant process computer system (PPCS) and auxiliary safety instrumentation panel (ASIP). A subsequent evaluation determined that temperature element ITE-451C had failed and required replacement. The inoperability is believed due to degradation of the sensing element. Troubleshooting efforts indicate that it is unlikely that the problem is a result of a faulty voltage-to-current (E/l) converter, cabling or containment splices.

Plans And Schedule For Restoration A work order has been prepared to replace the dual element resistance temperature detector (RTD) containing 1TE-451A and 1TE-451C during the upcoming Unit 1 fall 2005 refueling outage (Ul R29), which is scheduled to start September 24, 2005. Full restoration is expected prior to completion of the outage.

Additional Plans NMC plans to recalibrate the respective instrument loops after replacement and repairs.

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