Ex-Vessel Delayed Neutron Detection Systems for the ASTRID Sodium-Cooled Fast Reactor

Abstract

Monitoring fuel integrity during sodium cooled fast reactor operating is a particular issue when sodium uranoplutonate formed consecutively to a clad aperture will fostered cooling defaults. Delayed neutron detection systems are key tools allowing preventing and mitigating such an accident by monitoring the concentration of delayed neutron precursors contained into the coolant. DND systems operate in hard gamma rays flux and low neutron activity level. They have to be carefully optimized in order to detect as early as possible dangerous failures. A discussion has been conducted about the best way to design a DND system and some conclusions have been obtained.