Hybrid Systems State of the Art and Prospects

The present work was started in the framework of the ENEA contribution to the Nuclear Energy Agency (NEA) Task Force on Physics Aspects of Trimsmutation. Taking into account the present interest in the hybrid systems technology. the paper was completed adding the initial developments concerning the systems devoted to flssile material production, together with the more recent developments regarding systems dedictited to electrical energy production. In the last phase some parts of the original works describing the systems were included in the text. The hybrid (accelerator-subcritical reactor) systems were thought to produce fissile material to avoid shortage before the discovery of the real omount of uranium in the world. Later these systems were studied for transmutation of long lived waste. At present. there are some proposals for their use as electrical energy production Hybrid systems consist of a target (generally heavy metal) producing many neutrons from incident proton. The neutrons are introduced in a subcritical blanket. In the present paper the main hybrid system concepts are described. The commercial introduction and