MYRRHA mechanical design: The in-vessel fuel transfer and storage

The fuel handling is performed from underneath the core. There may be insufficient space to (un)load the core from above because of the interference of the core with the spallation loop and proton beam, the fact that the room situated directly above the core will be occupied by lots of instrumentation and experimental irradiation devices penetrations, and core compactness.

Because of the off-centre position of the spallation loop, there are two fuel handling systems that are inserted in penetrations of the reactor cover on opposite sides of the core.

Spent fuel still generates decay heat and must remain in the coolant for some time after the reactor is shut down. To avoid excessive delay between two operation cycles, it was chosen to store the spent fuel at the periphery of the reactor.

Since there are two fuel manipulators, there are two fuel storage zones (item 7). Each fuel storage provides 102 positions, i.e. 204 positions in total. The two storage zones together allow then the storage of two fuelled cores (2 times 72 positions) or one complete core (183 positions of fuelled and dummy assemblies); additionally, there is a provision for ~ 10 additional positions in each storage zone for absorbing assemblies that might be applied during core reshuffling. 

Reactor internals