John Downer is a 2011-2012 Stanton nuclear security postdoctoral fellow at CISAC. In 2010-2011 he held a joint appointment as lecturer at Stanford's Science, Technology and Society program and as Zukerman postdoctoral fellow at CISAC. He was educated at the universities of Edinburgh and Cambridge before receiving his doctorate from Cornell University. His thesis, entitled "The Burden of Proof: Regulating Ultra-High Reliability in Civil Aviation," looked critically at the theory and practice of auditing the risks of critical technologies. Prior to joining CARR he held a research position at the London School of Economics (LSE) Centre for Analysis of Risk and Regulation (CARR). In this presentation, Downer will analyze an influential 2005 IAEA report that implied that the Chernobyl accident will kill no more than 4000 people, with an eye towards the model of science it presumed and the points of dissonance between it and the increasing number of qualitative and quantitative accounts that challenge its conclusions.