In the nuclear engineering scientific community, accelerator-driven systems (ADSs) have been proposed and investigated for the transmutation of nuclear waste, especially plutonium and minor actinides. These materials have a quite low effective delayed neutron fraction relative to uranium; therefore the subcriticality of the core offers a unique safety feature with respect to critical reactors. The intrinsic safety of ADS allows the elimination of the operational control rods; hence the reactivity excess during burn-up can be managed by the intensity of the proton beam, fuel shuffling, and eventually burnable poisons. However, the intrinsic safety of a subcritical system does not guarantee that ADS are immune from severe accidents (core melting) since the decay heat of an ADS is very similar to the one of a critical system. Normally, ADSs operate with an effective multiplication factor between 0.98 and 0.92, which means that the spallation neutron source contributes only 2–8% to the neutron population. For 1 GeV incident protons and lead-bismuth target, about 50% of the spallation neutrons have energy below 1 MeV and only 15% of spallation neutrons have energies above 3 MeV. In the light of these remarks, the transmutation performances of ADS are very close to those of critical reactors.

This special issue aims at stimulating contributions on the most recent advances in the development of computational methods for the simulation and the assessment of ADS technology. Potential topics include, but are not limited to:

• Accident scenarios
• Comparison of deterministic and Monte Carlo analyses
• Conceptual designs
• Discussion and comparison of different properties of critical and subcritical cores
• Experimental analyses and interpretations
• Fuel cycles, transmutation performances, and optimization
• Material damage
• Modeling of the spallation reaction
• Nuclear data and sensitivity analyses
• Thermal hydraulic analyses

Before submission authors should carefully read over the journal's Author Guidelines, which are located at http://www.hindawi.com/journals/stni/guidelines/. Prospective authors should submit an electronic copy of their complete manuscript through the journal Manuscript Tracking System at http://mts.hindawi.com/ according to the following timetable: