CRITICALITY SAFETY BASIS FOR THE IAEA TRANSPORT REGULATIONS

After PATRAM 2010, the IAEA initiated an ambitious effort to compile a technical basis document (TecBasDoc) covering the 2012 Edition of the Regulations for the Safe Transport of Radioactive Material (SSR-6). Radioactivity (including spontaneous fission) and criticality are the two identified hazards during transport that SSR-6 apply to. The objective of SSR-6 is nuclear criticality safety and radiation protection together. The scope of SSR-6 is movement of radioactive material, including fissile material, on various modes of transport (land, water, air), between nuclear sites. The radioactive material fits as a dangerous goods material (Class 7) into the international modal transport regulations. Criticality safety is protection against harmful consequences of an energy release from a criticality accident, preferably by prevention of the accident. This paper focuses on criticality safety while another paper focuses on radiation protection. A third paper on the TecBasDoc effort covers package testing, which is important for demonstration of compliance both of radiation protection and of criticality safety. The criticality safety provisions (requirements, options and specifications) of SSR-6 are add-ons to the radiation protection provisions. Practical concerns and safety concerns need to be covered in a transparent way (clear line between requirement at one end and objective and scope at the other end). The IAEA approach has basically worked well for more than 50 years. Experience and change industry needs have led to improvements (e.g. abandonment of the common Transport Index). The combination of criticality safety and radiation protection may still not be transparent to developers and users of SSR-6, e.g. radiation protection programme, excepted package, LSA-I, confinement system, and radioactive material. The IAEA TecBasDoc effort has led to a compilation of many documents, most in an electronic format, to support conclusions on the basis for the current SSR-6. Previous provisions and some discussions on proposals are justified since they provide essential information and support preparation of future proposals. The paper presents criticality safety in chapter 11 of the TechBasDoc. It will reference another, thicker document that contains more details, discussions and quotes from original papers. Chapter 11 is intended to cover all aspects of criticality safety in transport. The subchapter headings are reflected in the chapters of this paper. They are introduction, objective, scope, safety culture, definitions, general requirements, performance standards, demonstration of compliance, authorization and approval, preshipment controls (including UN number assignment), transport including transit storage and references. Each paragraph in SSR-6 will be referred to at least once in chapter 11 of the TecBasDoc. A lot more can be achieved. SSR-6 developers and users of can contribute to the quality of the TecBasDoc by providing additional information or by asking relevant questions, indicating missing information.