Characterisation of Radioactive Contaminated Waste: Alpha-Induced Air-Fluorescence Detection Under Daylight Conditions

Short travel of alpha particles in environments complicated the detection and characterisation of alpha-emitting contamination in mixed radiation fields in nuclear decommissioning sites. As a result, detection of alpha-induced radioluminescence became popular in nuclear decommissioning applications. The detection has to be done under dark conditions or special lighting conditions, in order to prevent interference of alpha-induced radioluminescence with background light. However, stand-off detection even under daylight condition, can be achieved by detecting alpha-induced radioluminescence in the ultraviolet C wavelength range (180-280 nm). We have demonstrated the use of an UVTRON flame sensor, which is solar-blind (developed by Hamamatsu), detecting photons in the ultraviolet C wavelength range. Ultraviolet C radioluminescence from a Po-210 sample was detected in normal lighting conditions using the UVTRON, with very low background counts found in all environments. As the Ultraviolet C radioluminescence signal is small, gas flows of Ar, Xe, Ne, N2, Kr and P-10 were directed over the Po-210 sample to enhance radioluminescence with positive effect. In one instance Xe doubled the count in relation to an air atmosphere.