05000373/FIN-2013003-02
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Finding | |
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| Title | Potential Failure to Assign Appropriate Safety Classification to Secondary Containment Doors |
| Description | The EACE 1414490, Unit 2 Reactor Building 761 Interlock Allows Both Doors to be Open, and EACE 1481207, Secondary Containment Door Interlock Failure, both document instances where both doors of an interlock in secondary containment were opened at the same time. This created a condition where secondary containment was declared inoperable and its safety function was considered lost. During the review of the EACEs and associated documentation, the inspectors noted that the secondary containment structure was classified as safety-related but the secondary containment doors were classified as nonsafety-related. Licensee engineering personnel stated that the classification went back to the original licensed design requirements and that the bases were addressed in NUREG-0519, Safety Evaluation Report Related to the Operation of LaSalle County Station Units 1 and 2. However, following the review of NUREG-0519 and the UFSAR sections associated with classification of structures, systems and components, and secondary containment functional design, the inspectors determined that there is no distinction between secondary containment and its doors. The design and licensing basis documents reviewed describe secondary containment as a system and did not list exceptions to its components such as the doors. The inspectors will discuss the issue with personnel in the NRC Office of Nuclear Reactor Regulation to help determine if the licensee is implementing the component classification guidelines and processes appropriately and if the classification of secondary containment doors is consistent with that of other licensees. The inspectors also reviewed LOS-CS-M1, Secondary Containment Integrity. This procedure outlines the steps to test the secondary containment doors as required per TS Surveillance Requirement (SR) to verify one secondary containment access door in each access opening is closed. The frequency stated for this TS SR is 31 days. The inspectors noted that prior to December 2011, the secondary containment doors were tested by opening one of the two interlock doors and physically challenging the other one to verify that the interlock mechanism had actuated, and the two doors could not be opened at the same time. However, in January 2012, operations personnel changed LOS-CS-M1 such that only the light indication would be checked, and the doors would not be physically challenged. The licensee stated that the reason for this change was to prevent inadvertent losses of the secondary containment function during the testing. The inspectors noted that merely checking the light to verify the interlock has engaged when one of the doors is open would not completely ensure that the doors will perform satisfactorily while in service. Specifically, since the light indication and the door lock are wired in parallel, a test could be determined satisfactory (based on the light indication) when the locking mechanism could be non-functional. This issue on secondary containment door testing is unresolved pending resolution of the inspectors question regarding the safety classification of the doors. An unresolved item is open pending further review by the NRC staff. |
| Site: | LaSalle  |
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| Report | IR 05000373/2013003 Section 4OA2 |
| Date counted | Jun 30, 2013 (2013Q2) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | B Palagi F Ramirez J Cassidy J Laughlin M Kunowski R Baker R Ruiz R Schulz T Gom Kunowskit Go M Learn R Edwards K Carrington M Ziolkowski R Jickling R Ruiz F Ramirez C Phillips |
| INPO aspect | |
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Finding - LaSalle - IR 05000373/2013003 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (LaSalle) @ 2013Q2
Self-Identified List (LaSalle)
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