This short history of nuclear regulation provides a brief over-view of the most significant events in the U.S. Nuclear Regulatory Commission's past. Space limitations prevent discussion of all the important occurrences, and even the subjects that are included cannot be covered in full detail. The first chapter of this account is taken from George T. Mazuzan and J. Samuel Walker, Controlling the Atom: The Beginnings of Nuclear Regulation, 1946-1962 (University of California Press, Berkeley, CA, 1984). The second chapter is largely based on J. Samuel Walker, Containing the Atom: Nuclear Regulation in a Changing Environment, 1963-1971 (University of California Press, Berkeley, CA, 1992). The third chapter is adopted in significant part from J. Samuel Walker, Three Mile Island: A Nuclear Crisis in Historical Perspective (University of California Press, Berkeley, CA, 2004). The findings and conclusions on events that occurred after 1979 should be regarded as preliminary and tentative; they are not based on extensive research in primary sources.

Since the dawn of the Atomic Age, nuclear experts have labored to imagine the unimaginable and prevent it. They confronted a deceptively simple question: When is a reactor “safe enough� to adequately protect the public from catastrophe? Some experts sought a deceptively simple answer: an estimate that the odds of a major accident were, literally, a million to one. Far from simple, this search to quantify accident risk proved to be a tremendously complex and controversial endeavor, one that altered the very notion of safety in nuclear power and beyond.   Safe Enough? is the first history to trace these contentious efforts, following the Atomic Energy Commission and the Nuclear Regulatory Commission as their experts experimented with tools to quantify accident risk for use in regulation and to persuade the public of nuclear power’s safety. The intense conflict over the value of risk assessment offers a window on the history of the nuclear safety debate and the beliefs of its advocates and opponents. Across seven decades and the accidents at Three Mile Island, Chernobyl, and Fukushima, the quantification of risk has transformed both society’s understanding of the hazards posed by complex technologies and what it takes to make them safe enough.