FEED BACK ON THE USE OF THE MX6 AND MX8 MOX FUEL TRANSPORT CASKS

The MX6 and MX8 casks have been developed by TN International to transport fresh MOX fuel assemblies for either BWRs or PWRs. The MX6 is used in nuclear power plants (NPP) in Germany and Switzerland to replace the previous Siemens type II and Siemens BWR casks. In France, the MX8 is used to replace the previous FS69 cask. Innovative solutions have been applied to each stage of design and manufacturing of the MX casks, which comply with TS-R-1 regulations (IAEA 1996). The design includes effective neutron shielding for high plutonium content fuel and easy-to-use content restraining systems. The large payload of the MX ( 6 to 8 PWR MOX fuel assemblies or 16 BWR MOX fuel assemblies) contributes to optimize the dose uptaken during unloading at the NPP. Moreover, new sequences for dry loading and dry or wet unloading operations were proposed for testing and implementation in nuclear facilities. In all, more than 100 shipments have been performed with these casks since the last five years. During initial operations sequence, TN International worked to improve the casks, for example by reducing operator exposure and optimizing turnaround times. The MX casks are currently used primarily in French, German and Swiss NPPs. Their use will be extended worldwide, starting with Japan.