RATIONALE FOR THE DEUTERIUM AND BERYLLIUM LIMITATIONS IN THE MODIFIED PARA. 672(A) IN IAEA TRANSPORT REGULATION

Para. 672 in the IAEA Regulations (TS-R-1)1) shows the exceptions from the requirements for package containing fissile material. This provision is important and widely applicable for the reasonable transportation of material with small amounts of fissile material. But deuterium and beryllium are restricted to less than 0.1% of the maximum allowable fissile material mass in para. 672(a) in the 1996 version (shown in Appendix-1). It means the maximum allowance is just less than 0.4 grams. This is because the fissile material limitations in the provision are based on minimum critical mass for the hydrogenous material and deuterium or beryllium may be more effective than hydrogen in terms of critical safety2),3). Deuterium exists naturally in hydrogen (about 0.015 atomic%) and the average concentration of beryllium in the earth’s crust (Clark Number) is 1.5ppm4). Massive LLW (Low Level Waste) that is stabilized by cement has been transported by exclusive ships in the world. Total deuterium mass naturally contained in the consignment might have exceeded several hundred grams. As a result, the LLW should be classified as fissile material even though there is no possibility of reaching critical. To rationalize the situation, the revised proposal have been submitted from Japan sequentially based on the detailed quantitative evaluation of deuterium and beryllium on their effects. As a result, exception of deuterium with natural concentration in hydrogen from the restriction has been approved in the Regulations (TS-R-1) and the Advisory Material (TS-G-1.1) of 2003 version. Furthermore, exception of beryllium with less than 0.1% concentration from the restriction has been also approved in the 2007 version.