NRC 2005-0126, Post Accident Monitoring Instrumentation Report
| ML052850387 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 09/30/2005 |
| From: | Koehl D Nuclear Management Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC 2005-0126 | |
| Download: ML052850387 (3) | |
Text
A N1i Committed to Nuclear Excellene Point Beach Nuclear Plant Operated by Nuclear Management Company, LLC September 30, 2005 NRC 2005-0126 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 Monitorinq 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 19, 2005, one required channel of Unit 1 Containment Sump B Water Level 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 Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW 6590 Nuclear Road
- Two Rivers, Wisconsin 54241 Telephone: 920.755.2321 APOt
ENCLOSURE I POST ACCIDENT MONITORING INSTRUMENTATION REPORT TECHNICAL SPECIFICATION 5.6.6 POINT BEACH NUCLEAR PLANT, UNIT I
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 8 of TS Table 3.3.3-1 is Containment Sump B Water Level. Containment Sump B Water Level is provided for verification and long term surveillance of RCS integrity.
Containment Sump B Water Level is used to determine:
- containment sump B level accident diagnosis;
- when to begin the recirculation procedure; and
- whether to terminate safety injection (SI), if still in progress.
Condition Description On August 19, 2005, Unit 1 Containment Sump B Water Level Transmitter 1 LT-960 was declared inoperable due to occasional spiking. Troubleshooting and repair attempts were unsuccessful in restoring the transmitter to service. On September 18, 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 Page 1 of 2
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 Level transmitters 1 LT-960 and 1 LT-961 (and their associated instrument loops) are the two channels designated to meet the requirements of function 8 of TS Table 3.3.3-1 for Containment Sump B Water Level. 1 LT-961 and its associated instrument loop remain operable and will continue to be used to monitor containment sump B level. I LT-959 monitors containment sump A water level and provides an overlap capability into the indicating range for 1 LI-960 and 1 LI-961. Therefore, 1 LT-959 could also be used to monitor the lower level portion of sump B.
Cause Of The Inoperability Containment sump B level indicator, 1LI-960, was observed to take a step jump of greater than 5 inches and appeared to be drifting higher. The indication from 1 LI-960 has been erratic; usually indicating 0 inches (normally expected level), followed by short excursions indicating greater than normal level. Troubleshooting efforts indicated that the problem was at the containment penetration. Work was performed to check the cable connection at the exterior of the containment penetration; however, the cable connection on the interior of the containment penetration needs to be checked to identify the fault based on time domain reflectometer results.
Plans And Schedule For Restoration A work order (WO# 0511279) was prepared to perform the initial troubleshooting. This work order has been added to the Unit I fall 2005 refueling outage (UI R29), which was started on September 24, 2005. Unit 1 Containment Sump B Water Level Transmitter 1 LT-960 is scheduled for restoration prior to completion of the refueling outage.
Additional Plans Further troubleshooting of the instrument is planned if no cable fault is identified at the connector on the interior of the containment penetration.
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