Modified notched energy filter neutron radiography camera for non- destructive determination of hydrogen content of irradiated BWR fuel elements

摘要

A neutron radiography camera operates in cooperation with a neutron beam source for determining hydrogen content of irradiated BWR fuel elements. The camera implements the method using a notched neutron spectrum filter to determine the hydrogen content. The camera is specifically configured to take advantage of the tubular geometry of a nuclear fuel rod. Incident neutron beam ports are formed in a base unit that receives an incident filtered neutron beam. The ports aim the neutron beam at a periphery of the BWR fuel elements, which in the context of nuclear fuel rods includes zirconium alloy cladding. Collision of the neutrons with hydrogen in the cladding lowers their energy and scatters them at preferential angles. Scatter cavities defining scattered neutron paths are formed in the base unit, and absorber plates are disposed of terminal ends of the scatter cavities. The absorber plates become activated by resonance absorption from the neutrons scattered by hydrogen in the target fuel elements. The hydrogen content can be determined from the activated absorber plates.