High power proton accelerators are being studied for their potential use in the transmutation of nuclear waste. The Second Workshop on Utilisation and Reliability of High Power Proton Accelerators, organised by the NEA Nuclear Science Committee, placed special emphasis on accelerator-driven system (ADS) concepts comprising a sub-critical reactor coupled with a high power accelerator. The information provided in these proceedings will primarily be of interest to scientists working on accelerator-driven systems, but also to those involved in the construction of high power accelerators.