A Review on Safety Issues and Analysis Tools for Accelerator Driven Systems and Transmuters

The accelerator driven transmuter systems (ADTs) introduce three innovations, compared e.g. to critical sodium cooled fast spectrum burner reactors. A subcritical reactor driven by an external neutron source, the heavy metal coolant and the new dedicated fuels. All three innovations introduce new interrelated safety issues. Besides the dynamics of the subcritical system and the chosen Pb/Bi or Pb coolant, especially the innovative fuels will be the key focus in the safety investigations. The success of the transmutation idea strongly depends on the fuel issue and the successful development of these fuels represents a corner-stone of the ADT program. These so-called dedicated fuels should allow a maximization of incineration/transmutation rates. They are characterized by a high Minor Actinide (MA) content and by the lack of classical fertile materials as U238. European R&D for ADS fuels within the 5th Framework Programme FUTURE has mainly concentrated on CERCER and CERMET oxide fuel forms. As matrix materials MgO and Mo are currently favored.. The safety behavior of these fuels is rather complex and significant R&D efforts are required. Strong interest focuses on the performance of these fuels under transient conditions and accident scenarios, also with the goal to identify any ‘show stoppers’. New phenomena and safety issues have been can be identified and will need closer investigation. The performance of these fuels can be viewed firstly under the aspect of the fuel behavior itself and secondly on their impact on the overall reactor safety parameters. Generally, the high MA load leads to