Radioactivity partitioning in incinerators for miscellaneous low-level wastes

Her Majesty's Inspectorate of Pollution (HMIP) authorises the use of hospital, university and Local Authority incinerators for the disposal of solid radioactive wastes. At present these authorisations are calculated on ''worst case'' assumptions, this report aims to review the experimental data on radioactivity partitioning in these incinerators, in order to improve the accuracy of HMIP predictions. The types of radionuclides used in medicine were presented and it is noted there is no literature on the composition of university waste. The different types of incinerators are detailed, with diagrams. Major differences in design are apparent, particularly the offgas cleaning equipment in nuclear incinerators which hinders comparisons with institutional incinerators. A comprehensive literature review revealed 17 references on institutional radioactive waste incineration, 11 of these contained data sets. The partitioning experiments were described and show a wide range of methodology from incinerating guinea pigs to filter papers. In general, only ash composition data were presented, with no details of emissions or plating out in the incinerator. Thus the data sets were incomplete, often with a poor degree of accuracy. The data sets contained information on 40 elements; those were compared and general trends were apparent such as the absence of H-3, C-14 and I-125 in the ash in contrast to the high retention of Sc-46. Large differences between data sets were noted for P-32, Sr-85 and Sn-113 and within one experiment for S-35. (author)