05000285/LER-2014-004
| Fort Calhoun Station | |
| Event date: | 4-24-2014 |
|---|---|
| Report date: | 10-3-2014 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| LER closed by | |
| IR 05000285/2014009 (18 September 2014) | |
| 2852014004R01 - NRC Website | |
Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 2055 5-0001, or b y Internet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB oontrd number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
BACKGROUND
Fort Calhoun Station (FCS) is a two-loop reactor coolant system of Combustion Engineering design.
EVENT DESCRIPTION
On April 24, 2014, during a review of previous conditions affecting equipment qualification it was determined that a condition repaired in 2012 and 2013 may need additional review for reporting.
During a comparison of vendor manual requirements in applicable plant procedures associated with the Fort Calhoun recovery efforts on May 3, 2012, it was identified that the environmental qualification of Namco EA180 series limit switches were not being properly maintained per vendor requirements in that revision 6 of maintenance procedure EM-RR-VX-0410, "Maintenance of Limit Switch Type EA-180 to Maintain EEQ Qualification," did not require the replacement of the limit switch top cover gasket and screw assemblies and torqueing of the top cover screws to 20 to 25 inch-pounds each time the top cover was removed. Instead, EM-RR-VX-0410 called for torqueing the limit switch top cover screws to 19 to 21 inch-pounds and did not call for the replacement of the limit switch top cover gasket and screw assemblies each time the top cover was removed.
The following components are within the scope of this issue:
FCV-326 - Shutdown Cooling Heat Exchanger Low Pressure Safety Injection (LPSI) bypass flow control valve HCV-1041A/1042A - Main Steam Isolation Valves HCV-1107/1108A/B - Steam Generator Auxiliary Feedwater inlet valves HCV-1387/1388 - Steam Generator Blowdown Isolation Valves HCV-238/239 - Reactor Coolant System Charging Line stop valves HCV-240 - Pressurizer Spray inlet valve HCV-241 - Reactor Coolant Pumps Controlled Bleed-Off Inboard isolation valve HCV-2504/2506/2507 A/B - Steam Generator Sample Line inboard and outboard isolation valves HCV-2603B - Safety Injection (SI) Tanks SI-6A - 6D supply inboard isolation valve HCV-2604A/B - Reactor Coolant Drain Tank (RCDT) supply isolation valves HCV-2898/2899A/B - Control Room Ventilation Unit Component Cooling Water (CCW) inlet/outlet valves HCV-2907/2908/2917/2918/2927/2928 - High Pressure Safety Injection (HPSI) suction/discharge valves HCV-2937/2938/2947/2948 - Low Pressure Safety Injection (LPSI) suction/discharge valves HCV-2957/2958/2967/2968/2977/2978 - Containment Spray (CS) suction/discharge Valves HCV-2916/2936/2956/2976 - SI Tank SI-6A/D fill/drain valves HCV-2987 - HPSI Alternate Header isolation valve HCV-304/305/306/307 - HPSI Header cross connect and isolation valves HCV-335 - Shutdown Cooling Heat Exchanger inlet header isolation valve HCV-425A/425C - SI Leakage Cooler combined CCW inlet/outlet header inboard isolation valve HCV-438A/438C - Reactor Coolant Pump (RCP) lube oil and seal coolers CCW inlet/outlet inboard isolation valve Fort Calhoun Station 05000285 Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 2055 5-0001, or b y Internet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB oontrd number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
HCV-467A/467C - Nuclear Detector Well Cooling Coolers combined CCW inlet/outlet header inboard isolation valve HCV-545 - SI Leakage to Waste Disposal System isolation valve HCV-746A/B - Containment Pressure Relief isolation valves HCV-864/865 - Containment Fan Cooler Charcoal Bed Fire Protection valves HCV-881/882/883A/884A - Hydrogen Analyzer Sample Containment Isolation valves MS-291/292 - Power Operated Main Steam Relief valves PCV-1849A - Containment Instrument Air inboard isolation valve PCV-2909/2929/2949/2969 - SI Leakage Cooler pressure control valves PCV-6680/6681A/B - Control Room Heating Ventilation and Air Conditioning (HVAC) filter control valves PCV-742A/B/C/D/E/G - Containment Purge isolation valves TCV-202 - RCS Letdown temperature control valve YCV-1045A/B - Turbine Driven Auxiliary Feed Water Pump (FW-10) steam supply valves This report is being submitted pursuant to 10 CFR 50.73(a)(2)(v), 10 CFR 50.73(a)(2)(vii), 10 CFR 50.73(a)(2)(i)(B) and 10 CFR 50.73(a)(2)(ix)(A). A verbal report was not required as this event is of a historical nature.
CONCLUSION
A cause evaluation was completed and determined that technical information from the vendor manual for maintaining environmental qualification of the Namco EA180 series limit switches was not captured in procedure EM-RR-VX-0410.
CORRECTIVE ACTIONS
Procedure EM-RR-VX-0410 was revised to include vendor information for maintaining environmental qualification of the Namco EA180 limit switches.
The limit switch top cover gasket and screw assemblies for affected environmentally qualified Namco EA180 series limit switches installed in the plant have been replaced and the associated top cover screws properly torqued to 20 to 25 inch-pounds.
SAFETY SIGNIFICANCE
With the exceptions noted below, the affected limit switches provide component position indication only; they do not impact the automatic operation of the affected safety systems. In some accidents, the operators would use supplemental indication to validate proper operation of safety system function. Validation of proper system operation is a normal part of the station emergency and abnormal operating procedures and operator training.
Fort Calhoun Station Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 2055 5-0001, or b y Internet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB oontrd number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
Limit switches on MS-291/292 will initiate the filtered air mode on Control Room Ventilation whenever either safety valve is opened. Design basis accidents that could affect these switches would not impact the dose to the operators. The operations staff is provided with self-contained breathing equipment should conditions indicate that it is necessary to minimize dose to the operators.
SAFETY SYSTEM FUNCTIONAL FAILURE
This does not represent a safety system functional failure in accordance with NEI 99-02, revision 7 as the limit switches will not prevent the automatic safety functions of the impacted safety systems.
PREVIOUS EVENTS
LERs 2012-015, 2012-017, 2013-011 and 2013-016 also report issues with environmental qualification.
Fort Calhoun Station 05000285