A probabilistic approach to the design of the travelling crane for handling containers of spent-fuel assemblies in nuclear power stations

Spent-fuel assemblies, after deactivation in the pond, are transported from the power station to the reprocessing centre in a special container. Its mass is substantial (100 tonnes), since it has to provide protection against the escape of radioactivity. If it were to be dropped during handling in the power station there could be serious consequences, for example to the structures: leakage in the deactivation pond, its emptying and exposure of assemblies, etc. It has thus been necessary to design a handling crane of such reliability that the risk of the container being dropped becomes very low. This paper indicates the method used and the advantage of representing the mechanical systems by failure trees; the method makes it possible to detect the weak parts and to concentrate design efforts where they are most necessary