1. Fuel presentation

Although it has evolved considerably since then, the concept of particle fuel dates back to the late 1950s. At the time, the idea was to study a fuel consisting of uranium finely dispersed in a conductive matrix of graphite, in particular, to improve exchanges between the gaseous coolant and the fuel. The concept then evolved into hotter helium coolant reactor systems, the High Temperature Gas cooled Reactor (HTR or HTGR) developed mainly in the 1960s and 1970s.

In Germany, for example, the AVR (Arbeitsgemeinschaft Versuchreaktor) experimental reactor, shut down in 1988, has demonstrated, in 22 years of very satisfactory operation (see dossier [ ] on high-temperature reactors), the viability of the concept, even for very high helium outlet temperatures (950 ˚C). In particular, the particle fuel performed extremely well in terms of radionuclide containment,...