Scientists at Russia’s AA Bochvar Research Institute of Inorganic Materials (VNIINM) have deigned methods for manufacturing fuel for high-temperature gas-cooled reactors.

“Microspherical fuel is a key technology in high temperature reactors (HTGRs), said Maxim Yudin, chief specialist for reactor fuel technology at VNIINM on 6 March. “They provide the ability to achieve high coolant temperatures up to 1000°C and efficient retention of fission products inside the micro fuel at fuel temperatures up to 1600°C,” he noted.

VNIINM is part state nuclear corporation Rosatom’s fuel company TVEL.

Scientists at VNIINM's department of fuel technologies for fast and gas reactors have developed draft technical documentation for the manufacture of experimental microspherical fuel based on uranium dioxide with TRISO (TRi-structural ISOtropic) coating.

The coating, comprising layers of porous pyrocarbon, dense pyrocarbon, silicon carbide and another layer of dense pyrocarbon, is sequentially applied to the fuel core, which protects the microfuel from external mechanical stress.

In addition, scientists developed a draft methodology for determining the geometrical parameters of a microfuel (diameter, non-sphericity coefficient, and thicknesses of coating layers) and carried out a monitoring of the operability of the selected method.