The mechanical design of the sub-critical core assures a safe and adequate cooling, a sufficient resistance against thermal and irradiation induced stresses, corrosion and erosion and foresees the necessary channels for experiments. The core is surrounded by a barrel with outer diameter of 1520 mm, which assures its integrity and serves as a main coolant duct. The core support plate situated below is designed to contain the instrumentation. Maintenance is performed after removing the core from the reactor vessel. |
 |
There are 183 available channels surrounding the spallation target block placed in the center. All the channels are able to receive a standard assembly; 8 channels are located under the penetrations in the reactor cover and can host irradiation devices, the in-pile sections (IPS). The IPS presents itself as a long tube inserted in the lid penetration. If the channel is filled by a standard assembly, the penetration is filled by a plug. The spallation loop has, in the centre of the core, a cross sectional shape of three adjacent assemblies. Several fuel configurations can be arranged, but in any case there are in average 75 channels to be loaded with fuel assemblies, limited by the total allowed heat output and sub-criticality requirements of the reactor. |
Nevertheless, the 193 channels have to be loaded with an assembly, even if the latter is an empty box or is filled with dummy fuel pins. The core and the spallation loop are interlinked by means of a slot in the core support plate and in the core barrel allowing the separation of the spallation loop from the core structures; conversely, the spallation loop vessel must carry all the necessary "patches" to fill the gaps left in the slot. The core support structure is the assembly of three main components: the suspension tube, the core plug and the core support plate. the core barrel itself is the part of the suspension tube located under the core support plate. For maintenance the core barrel with the suspension tube, the core support plate and the core plug attached to it, can be removed from the reactor. |