The Hf-Mo-Nb-Ta-Ti-W-Zr system of compositionally complex alloys have been studied in this work by means of density functional theory modelling techniques in order to understand the usage of these novel alloy systems within the nuclear sector. Especially, this endeavour has sought to meet the materials design criteria for an interlayer material between zirconium-based fuel claddings, used in current light water nuclear reactors, and current chromium coatings, using compositionally complex alloys that are characterised as compositing four or more metallic elements in close to equal ratios.