Developments of the dismantling of Mark-II fast breeder assemblies with respect to the reprocessing (concept definition). Final report

For the reprocessing of Mark-II type fast breeder fuel assemblies (with spark eroded grid type spacers, which are fixed to the wrapper tubes by skirts) the fuel pins have to be removed from the fuel assembly in such a way, that they can be delivered individually or in groups to the fragmentation process. With respect to the removal process the influences of different possible deformations of the pins, spacers and wrapper tubes have been investigated in individual tests, and the loading capacity of the involved components has been tested. The results of these tests have lead to some design changes of the fuel assemblies (pin cell diameter increase, soft spacers, modified pin concept) and to a reference concept of the Mark-II fuel assemblies. As an experimental confirmation of the dismantling process under hot-cell conditions a dismantling device with CO2-laser was erected. Successful tests were run with this facility