TRU Waste.

Combining Passive Active Neutron / Gamma Energy Analysis with process or acceptable knowledge (the PAN/GEA/AK technique) has been successfully deployed for the characterization of contact handled (CH) transuranic (TRU) waste in accordance with the regulatory requirements. For most CH TRU streams Pu240 is the dominant source of spontaneous neutron emission, Pu239 is the dominant fissile isotope. Thus the signal from passive coincidence techniques may be attributed to Pu240 and the active neutron signal may be attributed to Pu239. Gamma spectroscopy (or AK data where insufficient gamma data is available) is then used to discriminate the other nuclides contribution to the active and passive signals. For Remote Handled TRU (defined as containers with external dose rates in the range 0.2 to 1,000 R/hr) it is often mistakenly believed that active and passive neutron techniques are not appropriate, because (i) isotopics are difficult to determine by gamma spectroscopy (ii) the waste streams are more diverse with isotopes such as the spontaneous neutron emitter Cm244 present for which there is no means to discriminate against. Both of these points are undeniably true – isotopics measurements are compromised by the Compton background and there is no easy means to discriminate different spontaneous neutro