Nuclear Fuel – Myths and Realities
The revival of interest in nuclear power, apparent over the past few years, can be explained by a combination of three factors. Firstly the improvement in the perceived economic viability of running nuclear reactors to generate electricity (indicated by the renewed interest of the financial sector) and then also the contributions that more nuclear power may make towards both curbing global carbon emissions and to enhancing energy security of supply. This return to the spotlight for nuclear has not been without some controversy and one area that has come under scrutiny is the fuel necessary to run the power reactors. There are some important questions worthy of detailed discussion, such as will there be enough uranium to satisfy rising future requirements (especially if the number of reactors doubles or even quadruples), does an increased quantity of nuclear fuel constitute a proliferation risk, could rising uranium prices threaten the economic viability of nuclear and are the procedures within the nuclear fuel cycle adequate to protect workers and the general public from any possible incremental health risks? These are just some more obvious examples, but answers in the negative could serve to hinder the mooted nuclear renaissance.
The nuclear fuel cycle
The most obvious point to make about the supply of nuclear fuel is that the underlying fuel cycle is rather complex, especially by comparison with the supply of the fossil fuels, coal, oil and gas, for electricity generating stations. Although oil goes to a sophisticated refinery (where the barrel is divided into separate elements to service the needs for electricity, transportation and chemicals), in common with coal and gas it is just a matter of getting it out of the ground then onto a ship, train or into a pipeline to reach the generating station where it is burned to create the heat which drives the turbines. Nuclear is also a "thermal" mode of generating power, relying on heat, with much of a plant very similar to the fossil fuel powered stations. It's the process used to create the heat, nuclear fission rather than combustion, and the required fuel with its attendant production cycle which is distinctive.
The key features of the nuclear fuel cycle (see Figure 1) are worthy of some initial discussion.1 Uranium is mined (via processes which give rise to waste streams, mainly tailings) and then converted, usually enriched (for 90% of the reactors around the world, increasing the share of the U-235 isotope beyond the natural 0.7% and creating depleted uranium of lower assay) before being fabricated into fuel to be introduced to the reactor. This is termed the "front end" of the cycle, before the generation of electricity in the reactor. This is the most important stage as it is this which brings in the only revenue - the sale of billions of kilowatt hours of electricity necessarily supports all the other activities, in the absence of any government subsidies or any alternative kindly benefactor.
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1 Further detail on the fuel cycle is provided at http://www.world-nuclear.org/info/inf03.html