PuO₂ and Fuel Residues

The decommissioning and decontamination of environments that are heavily contaminated with plutonium residues would benefit significantly from an in-situ characterisation technique providing an assessment of the distribution, ideally via an imaging technique with which to complement information derived from laser scans.  There are many techniques based on g-ray collimation that work satisfactorially for fission fragments, particularly ¹³⁷Cs .  These include Radscan, Cartogam and N-Visage, but the g emission from plutonium is too weak to benefit from such methods.  We propose to develop a technique based on the collimation and detection of fast neutrons, based on significant prior art at Lancaster, with which to assess the distribution of plutonium (based on the proportion of spontaneously-fissioning even-numbered isotopes).  This will enable plutonium content to be separated in decommissioning environments from fission fragment radioactivity without the need for swabbing and man entry.  It will provide valuable insight to inform decontamination plans of such environments and the assessment of plutonium material present.  It will also be relevant to the security and integrity assessment of plutonium storage environments.