Uranium as an energy source: medium to long term prospects

Abstract

Uranium is the only metal used as energy source.1 The extraction of uranium from the Earth’s crust involves a complex chain of physical and chemical separation processes and the consumption of large quantities of energy, and of different chemicals.The energy and chemicals consumed during extraction increase exponentially with decreasing ore grade, accompanied by an exponentially increasing emission of CO2. The grades of the available uranium resources decrease with time, because the mining companies mine the richest resources first, and because these offer the highest return of investment. Above phenomena cause the existence of the “energy cliff” and the “CO2 trap”. They thus call into question, for the century to come, the viability of a nuclear based solely on 235U extracted from natural uranium whose geological occurence couldn’t suffice to make it self-evidently an energy resource.One way to overcome this 235U limitation would be to exploit 238U resources. Nevertheless, this requires the industrial development and worldwide deployment of reactors operating in fast neutron mode (e.g. FNR). However a significant share of the energy produced by such reactors is difficult to envisage at a world level before the end of this century, as we shall see in this article.