Methods for the analysis of hypothetical reactor meltdown accidents

The COMMICS/CORRAL system of meltdown models describes the thermal-hydraulic conditions and the release and transport of radionuclides within containment. The principal output of the system of models is the time dependent release of radionuclides from the containment building. Numerous intermediate results include the time and duration of core melting, chemical reaction effects, containment pressure and temperature response, fission product removal by safeguards as well as natural processes, etc. The purpose of this paper is to describe the current status of the COMMICS/CORRAL code package which is under continuing development. Each of the major modules of the system is described. Alternative approaches and models available at other laboratories are also discussed. In addition model uncertainties and experimental data needs are described