Containment System Design and Post-LOCA Radiation Safety Analysis Using the FISSCON II Code

Abstract

The computer code FISSCON II predicts fission product behaviour in containment following a LOCA. The models involved simulate both natural and engineered processes including radioactive decay, plateout, washout, desorption, leakage and filtered exhaust. The code was originally developed at Ontario Hydro as a containment system design tool to assess the design of special containment subsystems including the Filtered Air Discharge System (FADS). More recently, it is being used for radiation safety analysis in support of reactor licensing submissions. This paper outlines the variety of uses of FISSCON II in safety analysis and containment design, including the determination of subsidiary design requirements such as radiation shielding and cooling for the FADS, stack activity monitoring, and environmental qualification of equipment. Code validation against experiments and observations, including those observations at Three Mile Island, is also discussed.