Development of SiC-based Neutron Detector Heads for High Radiation Environments

The development of SiC-based neutron detector heads are designed for high radiation environments, such as the Primary Containment Vessels (PCVs) at the Fukushima Daichi Nuclear Power Plant. The detectors utilise enriched B10 as a conversion layer, with Geant4 simulations used to optimise the efficiency for neutron capture and reduce self-attenuation losses. The SiC diodes are electrically thinned for excellent gamma rejection. Each detector head contains up to two hundred eighty-eight sensors in various geometric configurations for maximum detection area. The modular construction allows for reconfiguration for deployment in a range of mixed neutron gamma fields. Preamplifier and amplifier circuits were designed for minimal noise and charge pile-up; the readout chain combines signals from multiple sensors for transmission via a single long coaxial cable. Testing demonstrated reliable detection of neutrons (<10nv) in gamma environments higher than sixty sieverts per hour, indicating SiC diodes as suitable detectors for neutron radiation in high gamma radiation backgrounds.