A real-sized start-up monitoring module prototype for comprehensive test and irradiation campaigns of miniaturized neutron detectors according to the IFMIF-DONES baseline

The key system to know the neutron and gamma fields during the commissioning at IFMIF-DONES facility will be the STart-Up Monitoring Module (STUMM), which will include tens of very sophisticated and miniaturised detectors providing crucial information about the radiation fields. In particular, there will be MFCs (micro-fission chambers), ICs (Ionisation Chambers), SPNDs (Self-Powered Neutron Devices) and GTs (Gamma Thermometers). The current state-of-the-art does not provide answers about the performance of the detectors in the very specific working conditions inside the IFMIF-DONES Test Cell, as a very high spatial density of detectors inside the STUMM vessel, an extremely harsh environment with neutron flux up to 5·1014n/cm2/s and the need of long mineral cables (>30 m) to drive the very weak current signals from the irradiation area to the closest electronics cubicles available in the facility. Except for the extremely high neutron flux provided by IFMIF-DONES, all the other very critical conditions can be replicated by means of a 1:1 scaled prototype of the STUMM (STUMM-PROTO), which will be subjected to comprehensive testing and irradiation campaigns in order to increase the knowledge about the performance of the detectors above mentioned. The present work shows the wide range of capabilities offered by STUMM-PROTO as well as the current status of its construction and some first notions about the experimental campaigns to be implemented.