The Physics of Subcritical Multiplying Systems

In recent years an increasing interest is observed with respect to subcritical, accelerator driven systems (ADS), for their possible role in future nuclear energy scenarios, as actinide (Pu and MA) incinerators, and/or as claimed energy plants with potential enhanced safety characteristics. Important research programs are devoted to the various related fields of research. Extensive studies on the ADS behavior under incidental conditions are in particular made, for verifying their claimed advantage, under the safety point of view, with respect to the corresponding critical reactors. Related medium and long range scenarios are being considered to cope with a number of concerns associated with safety (power excursions, residual heat risk), as well as with fuel flow (criticality accidents, fuel diversion, radiological risk, proliferation). In the present work we shall comment on some issues relevant to these new reactor concepts, with the intent of giving a general view of the present state-of-the-art in the reactor physics domain. Specific calculation methods to be adopted for intercomparison analysis of these systems and experimental data interpretation are also discussed, as well as ongoing and perspective relevant experimental campaigns on experimental facilities.