Coated nuclear fuel

The high/very high temperature reactor (V/HTR) is being continually developed to help nuclear energy generation. An important safety feature of the reactor is the use of tristructural isotropic (TRISO) coated fuel made of a 90μm buffer layer of low density pyrolytic carbon, inner pyrolytic carbon (IPyC) at 40μm, 35μm of silicon carbide (SiC), and an outer pyrolytic carbon coating (OPyC) of 40μm. To improve rentability of nuclear technology, future V/HTRs will need to operate at higher temperatures and burn-ups than those used in the past. One approach in this direction involves the introduction of extra layers of PyC/SiC or a burnable poison layer, to mitigate palladium corrosion in SIC or control excess reactivity in the kernel. Overall, after four decades in the development of the V/HTR, advances in characterization and a better understanding of materials' properties are leading to a new era of fuel production, where tailored SIC and PyC coatings can be produced.