A Self-Powered Neutron Detector with a Fissile Emitter

A self-powered neutron detector (SPND) was developed and tested in a 250-kW TRIGA Mark II reactor, using 93% ²³⁵U-enriched uranium as emitter material. Contrary to conventional SPNDs where the charge transfer from emitter to collector is performed by electrons, the present detector current originates in the transfer of highly ionized fission fragments through a very thin insulation layer. The theoretical evaluations indicated a detector sensitivity increase of a factor of 100 compared with a commercial cobalt detector together with such other advantages as the same spectral response and the same burnup characteristics as the reactor fuel.