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| Entered date | Event description | |
|---|---|---|
| ENS 41702 | 17 May 2005 11:24:00 | On March 19, 2005, during refueling Outage 2R17, it was identified that a Flex-wedge disc intended for installation in a Containment Sump isolation valve, did not have a machined slot around the disc edge, as required by the purchase specifications. A feature of the flex-wedge design is to allow the disc faces to flex, thereby reducing the potential for thermal binding. The discrepancy was identified during pre-installation inspection; therefore, the disc was not installed in the plant. Considering that extensive machining and handling of the disc is necessary during installation, it is extremely unlikely that the discrepancy could have gone undetected. The outboard containment sump isolation valve is normally closed and receives a Recirculation Actuation Signal (RAS) to open when the Refueling Water Tank volume is depleted (post-LOCA) in order to shift the Emergency Core Cooling System (ECCS) suction to the sump. Had the subject disc been installed in this valve, the discrepancy could have resulted in thermal binding of the disc, thereby rendering a complete train of ECCS inoperable upon initiation of a RAS. The subject disc was manufactured by Crane - Aloyco, and was delivered to Arkansas Nuclear One in 1991. This condition was determined to be reportable pursuant to 10CFR21 on 5/17/2005. |