Impact of Beyond Design Basis Events like those at Fukushima on Used Fuel Management

Currently the only option for USA utilities for Used Nuclear Fuel (UNF) management is wetstorage in the fuel pools and/or dry storage of UNF on site. The use of on-site dry storage systems on an Independent Spent Fuel Storage Installation (ISFSI) has become the preferred alternative for many utilities, especially in the USA. AREVA TN’s proven safe and low risk horizontal above ground NUHOMS® storage system is one of the most widely used UNF dry storage system in the USA. The safety, security and beyond design basis (BDB) events after the 9/11 events in the USA and the Fukushima earthquake and subsequent tsunami in Japan changed the landscape of UNF management in the world. These BDB events resulted in AREVA TN reassessing the safety basis of the NUHOMS® storage system for events like these.The dry storage systems like NUHOMS® are expected to be stored at reactor sites for period longer than the initial licensed period of 20 years due to delay in final disposal solution. Therefore, blockage of air inlet and outlet cooling vents due to debris accumulation during flood, rain, mud or dust during longer storage period, effect of chloride induced stress corrosion and other corrosion induced cracks during longer storage periods were also reassessed for NUHOMS® system. After evaluating the NUHOMS® system for BDB accident conditions more severe than those in the original design basis, AREVA TN concluded that NUHOMS® system will withstand such events, both natural and man-made. This presentation will discuss this reassessment.