Critical analysis of methods employed for the transport of radioactive materials in installations with high radioactivity

The problem of transferring radioactive products, which are a source of irradiation or contamination, through the protective walls of nuclear facilities is gaining in importance as the specific activities handled increase. All transport operations include a transfer at the beginning and another at the end and it is during these two phases that the hazard to personnel is greatest. Early facilities treated transfer systems as services integrated into the main installation, and normally only one class of protection (against irradiation or contamination) was considered. The development of technology, the need to combine these two different classes of protection and the increase in the number of research facilities have resulted, at the international level, in a proliferation of transfer procedures. But no thorough comparison of these procedures has ever been carried out, much less a comparison of the efficiency of the different devices, their reliability, simplicity, operating speed and cost. The present analysis, which is based on extensive reference material and on the factual knowledge of a certain number of active facilities, classifies the types of transfer according to their basic technological characteristics - shielded facilities, contained facilities, and shielded and contained facilities. The different classes are again sub-divided into direct and indirect transfers, depending on whether the object or material in question is transported directly in the form in which it is transferred or in an auxiliary container that always remains outside the facility. The study deals mainly with solids, but it touches on the familiar procedures for the transfer of liquids, and on the conditions imposed on the entry of personnel. The study shows that economic data (efficiency, reliability, contamination rate, operating cost, etc. ) are rarely published and are in any case difficult to compare. For this reason, after pointing out the evident trends at the principal types of facility (reactors, radionuclide production and fuel reprocessing plants, etc.), the authors suggest a standard questionnaire that could form the basis of an international enquiry and thus improve our knowledge of the problems at issue in the interest of all. (authors)