Systematic Radiological Assessment of Exemptions for Source and Byproduct Materials (NUREG-1717)
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Subsequent to the publication of NUREG-1717, the zirconium industry provided additional data on particle size and occupancy times. They stated that facilities which handle and process zircon flours are rather dusty environments with a distribution of particle sizes which are typically 5 µm or greater. Although this was acknowledged in the text of the NUREG, the original calculations in NUREG-1717 were done using a particle size of 1µm (which is consistent with the ICRP recommendations on which 10 CFR Part 20 and Federal Guidance Report 11 are based) and occupancy times of 2000 hours, essentially full time. Increasing the particle size to 5 µm or higher decreases the dose and using a typical worker occupancy time of 20% would further decrease the dose. The NRC realizes that a typical average worker dose would be much lower than the worst case most conserative high dose presented in the NUREG. The agency will not use the results presented in NUREG-1717 as a sole basis for any regulatory decisions or future rulemaking without additional analysis.
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001
This report is an assessment of potential radiation doses associated with the current exemptions from licensing for the majority of Part 30 byproduct and Parts 40 and 70 source material in Title 10 of the Code of Federal Regulations (CFR). Doses were estimated for the normal life cycle of a particular product or material, covering distribution and transport, intended or expected routine use, and disposal using the ICRP 26 and 30 dose assessment methodology, which was incorporated into the current requirements of 10 CFR Part 20 in May 1991. In addition, assessments of potential doses due to accidents and misuse were estimated. Also presented is an assessment of potential radiological impacts associated with selected products containing byproduct material which currently may be used under a general or specific license and may be candidates for exemption from licensing requirements.