Wikipedia
CRAC-II is both a computer code (titled Calculation of Reactor Accident Consequences) and the 1982 report of the simulation results performed by Sandia National Laboratories for the Nuclear Regulatory Commission. The report is sometimes referred to as the CRAC-II report because it is the computer program used in the calculations, but the report is also known as the 1982 Sandia Siting Study or as NUREG/CR-2239. The computer program MACCS2 has since replaced CRAC-II for consequences of radioactive release.
CRAC-II has been declared to be obsolete and will be replaced by the State-of-the-Art Reactor Consequence Analyses study.
The CRAC-II simulations calculated the possible consequences of a worst-case accident under worst-case conditions (a so-called "class-9 accident") for a number of different U.S. nuclear power plants. In the Sandia Siting Study, the Indian Point Energy Center was calculated to have the largest possible consequences for an SST1 (spectrum of source terms) release, with estimated maximum possible casualty numbers of around 50,000 deaths, 150,000 injuries, and property damage of $274 Billion to $314 Billion (based on figures at the time of the report in 1982). The Sandia Siting Study however, is commonly misused as a risk analysis, which it is not. It is a sensitivity analysis of different amounts of radioactive releases and an SST1 release is now generally considered not a credible accident (see below).
Another significant report is the 1991 NUREG-1150 calculations, which is a more-rigorous risk assessment of five U.S. Nuclear Power Plants.