4.2 Risks from uranium mining, mine tailings, enrichment, and fuel fabrication

at higher dose rates. More recent human studies have now shown the use of DDREFs is incorrect.67,68 Since 2013, most international agencies have ceased using DDREFs, so the real risk of fatal cancer has increased to at least 10 percent per Sv. Unfortunately, the ICRP has not stopped using DDREFs.69 Thus, governments and the ICRP have not recognized the perceived increased risks of radiation, nor tightened radiation limits. There is still no international consensus on the risks of radiation. What is clear, however, is that the ICRP’s recommendations are conservative.

Radioactive waste can contain a wide range of radionuclides, whose atoms are unstable. When their nuclei disintegrate, they give off various forms of radiation. Many of these atoms have a high radiotoxicity, which is the degree to which a radionuclide can damage an organism. Their half-lives, the amount of time it takes for half the original amount present to decay, are often extremely long, they can be thousands or even millions of years.

In order to estimate the risk of a radionuclide to an organism, the following factors are important:

• radioactive decay modes: the emission of alpha particles, beta particles and gamma rays

• chemical compounds which contain the radioisotope

• solubility in water

• transport modes through the environment

• relative biological effectiveness: the ratio of damage from one type of radiation relative to another, given the same amount of absorbed energy

• radiotoxicity: usually based on specific activity, stated as radioactivity in bequerel (Bq) per gram

• dose conversion factor, which converts becquerel to sieverts.

• In most instances, exposures will be internal rather than external, so doses and risks will also depend on their uptake rates, metabolisms and excretion rates in humans.

No proper hazard classification scheme has yet taken the above factors into account for radionuclides. Such schemes already exist for chemicals and biocides, and calls have been made for such a scheme to be established for radioactive waste.70

4.2 RISKS FROM URANIUM MINING, MINE TAILINGS,

ENRICHMENT, AND FUEL FABRICATION

Uranium mining, mine tailings, enrichment, and fuel fabrication are collectively termed the ‘front end’ of the nuclear fuel chain. Health risks arise at each of these stages. Uranium is a radioactive substance naturally existing in the earth’s crust. Its deposits are more concentrated in areas of the world where

67 United Nations Scientific Committee on the Effects of Atomic Radiation 2014,

“Levels and effects of radiation exposure due to the nuclear accident after the 2011 great east-Japan earthquake and tsunami.” New York: United Nations Scientific Committee on the Effects of Atomic Radiation. 68 World Health Organization 2013. Health risk assessment from the nuclear accident after the 2011 Great East Japan earthquake and tsunami, based on a preliminary dose estimation. 69 Valentin, J. 2005, Low-dose extrapolation of radiation-related cancer risk. Annals of the ICRP, 35(4), pp.1-140. 70 Kirchner, G. 1990, A New Hazard Index for the Determination of Risk Potentials of Radioactive Waste Journal of Environmental Radioactivity, 11, pp. 71-95.