The reactor pressure vessels never fail. In 1995, UCS issued a report on the fragile condition of reactor pressure vessels at nuclear power plants. For example, the Yankee Rowe plant in Massachusetts closed in 1992 because its reactor pressure vessel had become brittle over time. Brittle metal can shatter, much like hot glass, when placed in cold water. Despite the closure of the Yankee Rowe plant and documented embrittlement at many other nuclear plants, the risk studies continue to assume a zero chance of reactor pressure vessel failure.
Risk is limited to reactor core damage.
They do not calculate the probabilities of other events that could lead to releases of radiation, such as fuel going critical in the spent fuel pool or rupture of a large tank filled with radioactive gases. Some of these overlooked events can have serious consequences. For example, researchers at the Brookhaven National Laboratory estimated that a spent fuel pool accident could release enough radioactive material to kill tens of thousands of people. 10 History shows there is a greater probability of a flipped coin landing on its edge than of these assumptions being realistic. Unrealistic assumptions in the PRAs make their results equally unrealistic.