Lately interest towards small modular reactors has increased. Their small size and modular nature cause their manufacturing to be easier and make them a cheaper alternative to bigger nuclear power plants. There are many different kinds of SMRs under planning, and one possible technology that could be used in them is HALEU fuel. In HALEU the concentration of the fissile uranium isotope U-235 is 5–20 %, which is more than in 3–5 % LEU, that is traditionally used in nuclear power plants.

In this bachelor’s thesis the differences in manufacturing, physical properties and manufacturing capacity of HALEU fuel compared to < 5 % LEU fuels are examined. In addition, different SMR technologies that potentially could use HALEU are explored.

The manufacturing of HALEU fuel requires more resources than < 5 % LEU because it needs to be enriched further. On the other hand, its higher enrichment leads to higher burnup in the reactor. Higher burnup for example allows the fuel cycle length to be longer. Higher burnup and longer cycle length affect the physical properties of HALEU, such as its thermal conductivity, reactivity coefficients and neutron fluence and flux. HALEU would cause less radioactive waste per unit of energy produced than < 5 % LEU. However, there have been fewer empirical studies done with HALEU fuel, and therefore there are many uncertainties with its usage and properties.

Due to its higher burnup and cycle length HALEU would fit many SMRs. For example, HTGR SMRs and fast SMRs would practically always require HALEU fuel. In SMRs which are operating today, Russian KLT-40S and Chinese HTR-PM use HALEU. Russia has in fact been the only commercial manufacturer of HALEU for a long time, but lately the United States have taken big strides in the development of HALEU manufacturing.