Abstract :
The paper discusses a chain nuclear reaction in a homogeneous mixture of U235–C60 fullerenes. The critical mass is calculated, and is shown to drop considerably when the fullerite moderator is transformed into a diamond-like form under pressure. A possibility to produce a homogeneous nuclear reactor subcritical when fullerenes are used as the moderator, but becoming supercritical in their transformation into a diamond-like structure has been considered.