MYRRHA mechanical design: The sub-critical core

The upper (outlet) nozzles of the fuel assemblies are inserted in the suspension holes of the core support plate from underneath. The fuel assemblies remain in these holes in the core support plate by the buoyancy force. A total of 183 channels in the sub-critical core, surrounding the spallation target, are available to house fuel assemblies.

Several fuel configurations can be arranged but there are on average 72 channels (equilibrium loading conditions) to be loaded with fuel assemblies. Each of the 183 channels has to be loaded with an assembly, even if the latter is filled with dummy pins, LBE or experimental rigs. Those peripheral dummy assemblies can act as shielding and provide some protection from the neutron flux for the surrounding structures.

 Core positions
183 positions in the core of which 8 for experimental irradiation devices