Exemption issues

Many situations arise where the health and environmental impact(s) of radioactive materials (sources, bulk materials, etc) are low enough to exempt the material from regulatory control. Regulation is expensive, and one of the major developments in recent years is the 'graded approach' in which the level of regulation is proportional to the assessed level of risk. Tables of exemption levels for most radioactive isotopes are provided in the IAEA Basic Safety Standards (BSS), which have been incorporated in ARPANSAs National Directory for Radiation Protection (NDRP). There are several concerns about the use of these tables, with respect to single isotopes and bulk materials containing mixtures of radionuclides (particularly NORM). For bulk materials the BSS specifically recommends that the values specified in the tables of exemption levels should be regarded as guidance only, and that a situation-specific assessment should be carried out. However, this recommendation was not included in the NDRP, and this seems to have caused considerable confusion for waste producers. Another source of confusion is due to the approach of specifying standard' exposure scenarios. The example of a surface landfill (bulk NORM waste) will be used to illustrate this problem. This example clearly shows that a range of exposure scenarios may have to be considered, and that a particular material may be exempt for one situation but not for another. The problem also extends to isotopes used in industry, medicine and research, the classic example being that of disposal of 1-131. The exemption limit for 1-131 is 100 Bq/g (or 1 MBq, whichever is the lesser). A regulator would most likely baulk at allowing a licensed nuclear medicine facility to dispose of 1-131 at a concentration just below 100 Bq/g, even though such a concentration would be exempt from notification and licensing. However, the NDRP does not cover the case of another type of facility using 1-131 at a concentration less than 100 Bq/g. Such a facility would not require a licence and could dispose of unlimited quantities of 1-131 providing the 1-131 concentration did not exceed 100 Bq/g.