INSAG-7: The Chernobyl Accident: Updating of INSAG-1, Safety Report Series, IAEA, Vienne (AT), Novembre 1992, p. 23 "The accident is now seen to have been the result of the concurrence of the following major factors: specific physical characteristics of the reactor; specific design features of the reactor control elements; and the fact that the reactor was brought to a state not specified by procedures or investigated by an independent safety body. Most importantly, the physical characteristics of the reactor made possible its unstable behaviour."
