05000353/LER-2011-001
| Docicettortaber | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3532011001R00 - NRC Website | |
DAY
ormFOrW1301(1 10)
NRCFORMMISA
(10-2010) LICENSEE EVENT REPORT (LER) U.S. NUCLEAR REGULATORY COMMISSION
CONTINUATION SHEET
Unit Conditions Prior to the Event Unit 2 was in Operational Condition (OPCON) 1 (Power Operation) at approximately 100% power. There were no other structures, systems or components out of service that contributed to this event.
Description of the Event
On Wednesday, January 26, 2011, Limerick Unit 2 was operating at 100% power and the 24-month "Remote Shutdown System - RHR Heat Exchanger Bypass Valve (HV-C-051-2F048A) Position Indication Calibration" (EIIS:BO) was in progress. The test failed when the transmitter (EIIS:XT) could not be calibrated. At 1545 hours0.0179 days <br />0.429 hours <br />0.00255 weeks <br />5.878725e-4 months <br />, Operations entered Technical Specification (TS) 3.3.7.4, Remote Shutdown System Instrumentation and Controls, action "a", which requires restoration of the inoperable channel within 7 days or being in HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The transmitter was repaired and restored to operable status on January 28, 2011, at 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br />.
An investigation determined that the main control room (MCR) indication for the valve position was identified as drifting out of tolerance on Friday, March 20, 2009, during the previous unit refueling outage (2R10). At the time of identification it was not identified that the loop transmitter was the cause of the drifting indication. The transmitter is shared by the MCR and remote shutdown panel (RSP) valve position indicators; therefore, the RSP indicator was inoperable for a 22 month period.
The RSP indictor was inoperable on April 11, 2009, at 2325 hours0.0269 days <br />0.646 hours <br />0.00384 weeks <br />8.846625e-4 months <br />, when the unit entered STARTUP (OPCON 2) at the conclusion of the refueling outage 2R10. Therefore, this event resulted in an entry into an OPERATIONAL CONDITION when a Limiting Condition for Operation was not met which is a nonconformance with TS 3.0.4. RSP TS 3.3.7.4 was also not .complied with when the requirement to restore the inoperable instrument within 7 days was not met. Therefore, this LER is being submitted pursuant to the requirements of 10CFR50.73(a)(2)(i)(B).
Analysis of the Event
There were no actual safety consequences associated with this event.
The potential safety consequences of this event were minimal. There was no MCR evacuation event during this period. The remaining operable instruments and controls on the RSP were capable of completing a remote shutdown during the affected period.
nRe FORM 366A (10-2010) The 2A RHR Heat Exchanger Bypass Valve has a 0% to 100% open position indictor in the MCR and an identical indication on the RSP. The MCR indication is normally energized and the RSP indicator is normally de- energized. No channel check is required by TS for the MCR indication, and the RSP indication monthly channel check only verifies that the RSP indictor is downscale. The RSP indictor is verified to indicate properly while energized during the 24-month channel calibration surveillance test. The required accuracy per the 24-month test is plus or minus 3.1%.
The valve is equipped with a position sensing element and transmitter.
The transmitter output is normally directed to the MCR indicator via a RSP transfer switch. The RSP transfer switch can also direct the transmitter output to the RSP indicator.
During this event the MCR indication was observed to drift from 100% open to 88% during a refueling outage. and the indicator was incorrectly identified as the degraded component. The actual degraded component was the shared transmitter; therefore, the RSP indicator was also inoperable and entry into the RSP TS action was required. The operators did not recognize the potential impact on the RSP instrument.
Cause of the Event
The root cause of the event was less than adequate administrative barriers were present to ensure the senior licensed operator properly assessed the RSP TS impact of the deficiency.
Corrective Action Planned A daily channel check will be added to the Operations daily surveillance tests for the MCR instruments that share instrument loops with RSP instruments.
Previous Similar Occurrences There were no similar events involving conditions prohibited by TS for inoperable RSP instruments for the last 3 years.
41i6 FORM 366A (104010) Component data:
Equipment:
Component Number:
Manufacturer:
Model Number:
2A RHR Heat Exchanger Bypass Valve Position Transmitter ZT-051-248A L200 Limitorque 66-14852 +pc FORM 366A (10-2010)