05000285/FIN-2008006-01
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Finding | |
|---|---|
| Title | High Contact Resistance on Main Steam Bypass Valve Relay Contractors |
| Description | The licensee\'s analysis evaluated extent of condition and concluded that control circuit devices, such as relays, control switches and process switches, can exhibit high contact resistance and render the control circuit inoperable. Therefore, the extent of condition was that other plant circuits were susceptible to high contact resistance. Initially, the licensee\'s actions to address the extent of condition were limited to EDG circuit components. Subsequently, the licensee expanded the scope of extent of condition to include functional importance determination (FID), Critical 1 (FID-1), CR105 relays. As a result of this review, the licensee identified five additional components requiring resistance checks: (1) the shutdown cooling suction header isolation Valves HCV-347 and HCV-348 relay contacts were checked for resistance and found to be acceptable; (2) the containment sump suction isolation Valves HCV-383-3 and HCV-383-4 were scheduled for testing during the 2008 refueling outage; and (3) the turbine driven AFW Lube Oil Pump LO-39-MS was scheduled for the 2008 refueling outage. The team\'s review of the corrective actions also determined that, as a result of commitments to the NRC related to a NOV, L1C-07-0120, the licensee planned to identify and develop maintenance strategies for FID-1 and FID-2 relays as part of the EROP. Additionally, on February 13, 2008, the licensee added corrective actions to replace the auxiliary contacts of the five components discussed above and to identify and correct FID-1 non-CR105 contacts in plant systems where lubrication may have been applied without vendor concurrence. The team\'s evaluation of the licensee\'s extent of condition concluded that, although the root cause analysis correctly recognized the potential for high-resistance contacts existing in a multitude of safety-related circuits and components, the application of the conclusions were narrowly focused and untimely. Specifically, the licensee failed to recognize that the GE type CR106 relays are identical to the CR105 relays, except that they include thermal overload relays. As a result, the CR106 relays were not included in the original review. Additionally, the licensee failed to recognize that the lubrication of the relay auxiliary contacts was a potential common cause failure affecting the FID-2 as well as the FID-1 CR105 and CR106relays. Therefore, the exclusion of FID-2 relays from the original scope of review was inappropriate. During the inspection, the station entered a forced outage due to an unrelated plant scram. Due to the team\'s questioning of the extent of condition, the licensee identified a population of 39 relays requiring inspection. These relays, involving both FID-1 and FID2 components, were subsequently inspected during the forced outage. The licensee determined the population of affected components by conducting interviews with electrical maintenance technicians to determine what types of components may have had lubricant inappropriately applied in the past and then comparing that population of affected components to previously identified FID-1 and FID-2 components. Although, through this process, the licensee probably identified the majority of the population of affected components, given the impromptu method for identifying the expanded scope of review, the team\'s level of confidence that the licensee had identified all of the potentially affected components was low. For example, the starter associated with the fuel transfer pump for the diesel-driven auxiliary feed pump was not added to the list of relays requiring inspection until prompted by the team. Nonetheless, the team concluded that the testing of the selected components would provide valuable insights on the extent of condition and the need for further actions. The licensee\'s forced outage inspection identified four components with as found contact resistance that exceeded the licensee\'s established acceptance criteria of < 1 ohm. These components included main steam bypass Valves HCV-1041C and HCV-1042C, volume control tank outlet Valve LCV-218-2, and the high head safety injection to chemical volume control system cross-tie isolation Valve HCV 308. The licensee documented the as found condition of the relays in CR\'s 200801763, 200801815, 200801768, and 200801780, respectively. The auxiliary contacts for HCV-308 were replaced and the valve declared operable. No immediate safety concerns existed for the\' other components. The licensee determined that two of those relays (FID-2 components) associated with main steam bypass Valves HCV-1041C and HCV-1042C needed further assessment to demonstrate operability. As an interim action, the licensee tagged the valves in their closed safety position. The licensee\'s final assessment is pending until the shutdown of the facility to allow for as found testing of the valves. The licensee evaluated the as found resistance checks for the other components that were checked during the forced outage and concluded that the components were operable considering the low contact resistance that was measured and past acceptable performance of the associated components (i.e. no previous failures had occurred with components associated with the potentially affected relays and auxiliary contacts). Pending the NRC\'s final evaluation of the licensee\'s assessment of the as found condition of Valves HCV-1041C and HCV-1042C, an unresolved item (URI) is opened to review any potential regulatory and risk implications (URI 05000285/2008006-01, High Contact Resistance on Main Steam Bypass Valve Relay Contactors) |
| Site: | Fort Calhoun  |
|---|---|
| Report | IR 05000285/2008006 Section 4OA4 |
| Date counted | Jun 30, 2008 (2008Q2) |
| Type: | URI: |
| cornerstone | No Cornerstone |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 95002 |
| Inspectors (proximate) | J Kirkland P Elkmann L Ellershaw D Stearns J Hanna W Walker M Young S Makor T Patez Dunhamg George C Long C Osterholtz A Della Grec |
| INPO aspect | |
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Finding - Fort Calhoun - IR 05000285/2008006 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Fort Calhoun) @ 2008Q2
Self-Identified List (Fort Calhoun)
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