Gas cooled fast reactors

The gas cooled fast reactor (GFR) is one of the 6 concepts selected for the 4. generation of nuclear reactors. Several GFR projects had been studied since the beginning of the sixties but the concept was given up in the eighties because of the absence of relevant advantages compared with sodium cooled fast reactors. The total absence of chemical reactivity of helium and its neutron transparency has given new assets to GFR. The article details the last GFR concept (helium cooled and carbide fuel) in terms of reactor design (particularly the fuel element) and of reactor safety. it appears that the neutronic counter-reactions are very efficient to compensate the low thermal inertia of the core in case of coolant loss. (A.C.)