Author name: Rodney C. Ewing

The primary waste form resulting from nuclear energy production is spent nuclear fuel (SNF). There are a number of different types of fuel, but they are predominantly uranium based, mainly UO2 or, in some cases, metallic U. The UO2 in SNF is a redox-sensitive semiconductor consisting of a fine-grained (5–10 µm), polycrystalline aggregate containing fission-product and transuranium elements in concentrations of 4 to 6 atomic percent. The challenge is to predict the long-term behavior of UO2 under a range of redox conditions. Experimental results and observations from natural systems, such as the Oklo natural reactors, have been used to assess the long-term performance of SNF.

As the world faces the consequences of global warming caused by the use of fossil fuels, there has been a resurgence of interest in nuclear power. However, there is no “silver bullet,” and each energy-producing system produces waste. This issue of Elements shows the importance of mineralogy and geochemistry in the safe management and disposal of the different types of waste generated by the nuclear fuel cycle.