However, evidence from other studies is also discussed and, where possible, integrated into the final quantitative assessment. To ensure better quality and completeness of the data, ENSAD focuses mainly on human-made severe accidents, but it includes also data on natural disasters, other non-energy-related accidents as well as on less severe human-made accidents, although with a lesser degree of completeness. Currently, it is considered the most complete and reliable source of information on human-made severe accidents in the energy sector.