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Conference Article: Long term potential risk due to thorium mining

Schapira, J.P.; Menard, S. (Institut de Physique Nucleaire, Orsay (France))

Abstract

As in the case of uranium, thorium extraction produces a certain amount of radioactive wastes, the so called mining residues, in which natural long-lived natural decay products are mobilized. Monazites, the most likely ores to be exploited first, in case of an extensive use of thorium as nuclear fuel, contain a certain fraction of uranium as well. One has studied potential long terms radiological impact of the residues originated from two typical monazites found in India and Italy, respectively poor an rich in uranium. In the case of the Italian monazite, uranium is supposed to be extracted at a level of 95%. For such monazites, the long term impact is completely governed by the residual uranium (presence of long-lived 238U descendants, 230Th (80,000 years) and/or 226Ra (1600 years)). However, for the two extreme cases studied here, the potential risks remain much smaller (by a factor lying between 20 to 50) than in the usual case of uranium mining. The risk due to radon is also correspondly reduced by the same factors. These significant differences between uranium and thorium mining have to be considered in view of some estimated long term real radiological impacts due to uranium residues, which could reach a value of the order of 1 mSv/year, the dose limit recommended for the public by the recent ICRP-60.

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key words: Fast Neutron Spectrum Systems, Nuclear Technology
Reference:
Advanced fuels with reduced actinide generation.Technical committee meeting, Vienna (Austria). 21-23 Nov 1995
International Atomic Energy Agency, Vienna (Austria)
IAEA-TECDOC--916, pp:55-63