NUREG-1150

NUREG-1150 ("Severe Accident Risks: An Assessment for Five U.S. Nuclear Power Plants", published December 1990 by the Nuclear Regulatory Commission (NRC) is a follow-up to the WASH-1400 and CRAC-II safety studies that employs the methodology of plant-specific Probabilistic Risk Assessment (PRA). The research team, led by Denwood Ross, Joseph Murphy, and Mark Cunningham, concluded that the current generation of nuclear power plants exceeded NRC safety goals.

"This study was a significant turning point in the use of risk-based concepts in the regulatory process and enabled the NRC to greatly improve its methods for assessing containment performance after core damage and accident progression." [1] However significant, and sometimes unrealistic, conservatisms were applied in this study [2] and it is (as of 2006^[update]) being replaced with a new state-of-the-art study entitled State-of-the-Art Reactor Consequence Analyses(see below).

Results of NUREG-1150 (page 12-3):

Using the data on pages 3-5, 3-7, 4-5 and 4-7 the probability of some U.S. plant having core damage is about 30% over 20 years - this number doesn't include containment failure, which is conservatively estimated at 8% for PWRs (page 3-13, weighting by the probabilities at the bottom) and 84% for BWRs (page 4-14, same technique). Assuming that the 104 current-design (2005) U.S. plants are similar to the two "typical" plants, the chance of a major release of radiation is under 8% every 20 years.

The typical BWR was the Peach Bottom plant and the typical PWR was the Surry plant.

Parts of NUREG-1150 were compiled by Sandia National Laboratories, which continues to do such research. [3]

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