Re: Response to Draft ICRP Document Radiological Protection against Radon Exposure
Dear Mr. Clement
Cameco is one of the world's largest uranium producers accounting for about 16% of the world's production. Cameco has controlling ownership of the world's largest high-grade uranium reserves and low-cost operations in northern Saskatchewan, Canada. We are also the largest US producer with in situ recovery operations in Wyoming and Nebraska. Cameco also produces uranium in Kazakhstan through a joint venture in situ recovery operation. Cameco holds premier land positions in the world's most promising areas for new uranium discoveries in Canada and Australia as part of an intensive global exploration program. Cameco is also a leading provider of processing services required to produce fuel for nuclear power plants, and generates 1,000 MW of clean electricity through a partnership in North America's largest nuclear generating station located in Ontario, Canada. Cameco is committed to having a safe, healthy and rewarding workplace and radiation protection is a key aspect of our efforts in this area. As such, we are keenly interested in ongoing developments in the understanding of the risks from radon progeny and how we can improve safety at our operations.
The draft ICRP report called Radiological Protection against Radon Exposure provides a system to manage and mitigate radiation exposures from radon and places much of its emphasis on non-occupational exposures. There are several areas that should be addressed to further improve the report. First, from an editorial point of view, the report would benefit from a rigorous technical editing to help to improve the language and clarify the intent of numerous sections.
The most serious technical issue is the need for greater clarity in the role that smoking plays in the overall risks from radon exposure. While smoking is mentioned as an important risk factor, a clearer explanation should be given of some of the new results from epidemiology studies that show per unit exposure the absolute risks from radon exposure are on the order of a factor of twenty higher for smokers than non-smokers.
On the topic of occupational exposures, we recommend that uranium mining be included in the section of occupational exposures, rather than its own distinct section. The steps needed to control radon progeny in a uranium mine are not fundamentally different than other industries dealing with Naturally Occurring Radioactive Materials (NORM). The general approach for the management of radon exposure as summarised in Figure 7 provides a reasonable high-level framework that should be encouraged for all situations. Addressing all occupational exposures in one section would help to stress that the same overall framework is being used. Some NORM industries and underground mines have more potential for radon progeny exposures than open pit or in situ recovery uranium mining operations. In addition, the uranium mining industry contributes only a small portion to the collective occupational exposure from radon progeny. As such, it is important to communicate clearly the need to manage all occupational radon exposures within the same framework as laid out by the ICRP. Our concern is that having a separate section for uranium mining encourages a misconception that this is only an issue for this particular occupational sector.
We note that reference is made to the ICRP adopting a dosimetric approach to radon and believe that this is acceptable, in as much as it agrees with the results from the epidemiology studies. However, we believe that more work is needed on the dosimetric model before it could be used to justify departures from nominal dose conversion factors, which have been confirmed by epidemiology studies. This further work includes how the dosimetric model handles smoking and validating it against individual epidemiology studies. We recommend that the ICRP make a clearer statement to this effect. At this stage we view the dosimetric model as primarily directed towards further scientific research, both at improving the actual model and the practical aspects of measuring the necessary parameters to apply it.
Regards,
Kari Toews
Program Manager, Occupational Safety
Cameco Corporation