05000348/FIN-2010004-01
From kanterella
Jump to navigation
Jump to search
Finding | |
|---|---|
| Title | Failure of Containment Isolation Valve to Provide Proper Indication for its Containment Isolation Function |
| Description | An issue of concern revealed itself regarding the licensees corrective actions associated with dual position indication of containment isolation valve Q1P16MOV3134, SW from RCP Motor Air Coolers. During minor design modifications, the licensee failed to adjust the torque switch setting to provide adequate margin between the torque switch setting and the limit switch setting of the Limitorque motoroperated actuator. On August 14, 2010, Q1P16MOV3134 failed to indicate closed during a normal quarterly surveillance test. The valve continued to have dual position indication, and thus the ability of this valve to perform its containment isolation function, was in question. The licensee entered technical specification (TS) 3.6.3 and closed another isolation valve to restore the function as required. This action resulted in a cooling source to containment air temperature being removed. During the afternoon hours of August 14, 2010, the Unit 1 containment average temperature exceeded its TS limit of 120 degrees F. TS 3.6.5 required the licensee to reduce average temperature below 120 degrees F within eight hours, or be in Mode 3 within six hours and in Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The license requested enforcement discretion on August 15, 2010, to maintain Unit 1 in Mode 1. Discretion was verbally granted by the NRC on August 15, 2010. The NRC determined that the requested enforcement discretion was necessary to avoid unnecessary transients as a result of compliance with the license condition and, thus, minimize potential safety consequences and operational risks. Q1P16MOV3134 is a six-inch Enertech butterfly valve operated by a Limitorque motor operated actuator. Each unit has three Enertech butterfly valves in the supply and return lines of SW from the RCP motor air coolers. Two of these valves provide a containment isolation function upon an engineered safeguards function (ESF) actuation. In 2004 and again in 2005, failures occurred where the Unit 2 valves had dual position indication after a demanded position during surveillance testing. In 2007, the licensee recognized the need to make these valves position limit switch seated, instead of torque switch seated, to correct the dual position indication problem. The licensee implemented minor design changes on all six valves to accomplish this corrective action. The licensee failed to recognize the torque switch settings needed to be increased to provide a margin between the limit switch seating value and the torque switch seating value. In 2008 and 2009, the licensee again experienced instances of dual position indication on these valves. In July 2009, the licensee created work orders to adjust the torque switch settings to ensure an appropriate limit to minimizing the potential for dual indication-type closing stroke results. Three of these work orders have been completed, and the remaining three are scheduled to occur in the future. The inspectors did not identify an immediate safety concern for this issue because the licensee modified the actuation circuitry of Q1P16MOV3134 to remove the torque switch. The licensee has the ability to perform this same temporary modification to the other two remaining valves as well. Additionally, the licensee plans to perform the scheduled work order on Q1P16MOV3134 and Q1P16MOV3135 during the upcoming RFO in October 2010 to properly adjust the torque switch settings. The inspectors determined in order to determine if a performance deficiency exists and disposition this issue of concern, additional inspection would be required to better understand: 1) the exact cause of the dual indications; 2) the extent of condition associated with this issue supported by review of the licensee CAP and associated work orders; and 3) the licensee planned corrective actions. This issue of concern was identified as unresolved item (URI)05000348/2010004-01, Failure of Containment Isolation Valve to Provide Proper Indication for its Containment Isolation Function. |
| Site: | Farley  |
|---|---|
| Report | IR 05000348/2010004 Section 1R12 |
| Date counted | Sep 30, 2010 (2010Q3) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.12 |
| Inspectors (proximate) | S Shaeffer R Reyes S Sandal P Capehart J Sowa K Schaaf E Crowee Crowes Shaeffer A Vargas J Sowa |
| INPO aspect | |
| ' | |
Finding - Farley - IR 05000348/2010004 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Finding List (Farley) @ 2010Q3
Self-Identified List (Farley)
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||