Investigating material attractiveness for an innovative metallic fuel design

This paper investigates the material attractiveness for an innovative fuel design (IFD) based on Lightbridge's metallic fuel (MF) design. The used MF will have a plutonium vector that offers lower material attractiveness than traditional used uranium oxide fuel because of its high ²³⁵U concentration (19.7%), allowing for higher fuel burnup. An IFD was modelled using published information from Lightbridge. This paper presents analysis carried out on the IFD to assess its material attractiveness. The IFD was burned for 21 atom percent, equivalent to 190.9 GWd/MTU, for 1150 days – two 18-month cycles— which translates to 88.32 kW/fuel rod. This IFD power level is a 13% uprate to a traditional uranium oxide fuel burned at a level of 44 GWd/MTU for 1150 days, a power of 67.94 kW/fuel rod. This configuration of the IFD offers a one-to-one replacement of the traditional uranium oxide fuel rod in a pressurized water reactor (PWR). Additionally, the fresh IFD was doped with three different actinides (²³⁸Pu, ²³⁷Np, and ²⁴¹Am) from 0.1 to 1 wt% and the resulting plutonium vector's material attractiveness were evaluated using Bathke's Figure of Merit 1 and 2. The figure of merit (FOM) analyses showed that the non-doped used IFD has medium attractiveness as compared to the high attractiveness of traditionally used uranium oxide fuel. The doped IFDs had medium attractiveness with the FOM values slightly decreasing with increasing dopant concentration. In the FOM estimations, the radiation dose term was neglected as its contribution was insignificant due to the relatively small gamma signature from plutonium isotopes. Overall, the IFD analyses highlights that the actinide doped MF can yield used fuel which is unattractive.