The inspectors identified indications on the negative plate straps of multiple cells of station battery
71SB-1 and one cell of station battery
71SB-2 that visually appear to be cracks. The inspectors first identified an indication on cell 23 of station battery
71SB-1 on May 1, 2008, and Entergy initiated
CR-JAF-2008-01453. Subsequently, the inspectors identified cells 6, 33, and 56 on station battery
71SB-1 and cell 56 on station battery
71SB-2 as also having similar indications. As a result, Entergy initiated
CR-JAF-2008-01475 for multiple cells having indications with the appearance of cracks. Entergy prepared an operability evaluation and performed a calculation that assumed every indication to be a crack that proceeded completely through each plate strap, losing the capacity of a number of plates in each affected cell. The
operability determination demonstrated that the station batteries were capable of performing their design function. Entergy plans to remove cell 23 from service in their next refueling outage. Cell 23 will be disassembled and the negative plate strap thoroughly inspected in order to characterize the indication. The results of these planned inspections are required in order for the NRC to complete the inspection. Pending this review, the issue is considered an unresolved item (
URI):
URI 05000333/2008003-01, Station batteries with indications on the negative plate straps
