Exemption levels for transport of ores and concentrates containing uranium or thorium

Prior to 1996, the exemption concentration for transport of radioactive material was simple: 70Bq/ g for all radionuclides, or mixtures of radionuclides. It was clear however that this limit had little if any radiological justification. The development of the 1996 IAEA Basic Safety Standards (BSS 115), which gave 'exemption levels' for most radionuclides, prompted a change to make the exemption levels for transport more closely related to radiological risks. While leading to a more rational basis for exemption, this change has added some elements of confusion into the situation for uranium or thorium ores and concentrates