WASH-740


WASH-740 was a report published by the U.S. Atomic Energy Commission in 1957. This report, called "Theoretical Possibilities and Consequences of Major Accidents in Large Nuclear Power Plants", estimated maximum possible damage from a meltdown with no containment building at a large nuclear reactor.
The conclusions of this study estimated the possible effects of a "maximum credible accident" for nuclear reactors then envisioned as being 3400 deaths, 43,000 injuries and property damage of $7 billion. The estimate of probability was one in a hundred thousand to one in a billion per reactor-year. When WASH-740 was revised in 1964-65 to account for the larger reactors then being designed, the new figures indicated that there could be as many as 45,000 deaths, 100,000 injuries, and $17 billion in property damage.
However, the assumptions underlying the results were unrealistic. These were due to conservatism and the need to use atomic bomb fallout data, which had been collected from tests.
As knowledge, models and computers improved the conclusions of this report were replaced by those of first WASH-1400, then CRAC-II, and most recently NUREG-1150. Now all of these studies are considered obsolete, and are being replaced by the State-of-the-Art Reactor Consequence Analyses study.