Operational Experience of Castor 440/84 Casks in Dukovany NPP

The paper describes the current situation in operational experience in the Dukovany NPP (Czech Republic) focussed on the monitoring experience. A Czech power utility CEZ plc decided on a new technology in the storage of spent nuclear fuel in the end of eighties. The main feature is dual-purpose metal CASTOR® 440/84 cask for fuel assemblies of Russian type VVER 440. The first building was designed for 60 casks and the proposed life time is 40 years since 1995. In 1999 CEZ plc adopted a concept for the fuel cycle back end for its nuclear power stations. To implement the strategy for spent fuel management, the Long Term Spent Fuel Storage Preparatory Programme of CEZ was developed and subsequently approved in June 2000. Main key aspect relating to spent fuel: the first spent fuel should be handed over to the governmental authority into final disposal after 2065 at the earliest. The CASTOR® 440/84 is a dual-purpose metal cask and provides dry storage of 84 assemblies in a 100 % helium atmosphere. The cask is monitored according to the design by a system which measures the pressure in the gap between the primary and secondary lid. The measurement of surface temperature is another monitoring system. Main monitoring systems: