ABSTRACT
In the severe accident analysis of 1ight water reactor power plants fission product behavior and transport and eventually release from the containment plays a decisive role in the assessment of the radiological source terms. Although the emphasis in modelling fission product behavior and transport in containments lies on the aerosol codes the special behavior of iodine and its compounds should be considered separately because iodine can exist in a number of different chemical states which come together with a wide variation of chemical environments to which the fission product can be exposed during a severe accident. Nuclear aerosol behavior modelling has always been an applied discipline of aerosol physics. Aerosol codes have been extensively compared to experiments. Recent large scale experimental programs provided an invaluable data base for code validation. The major difference between the codes is in their modelling of condensation onto the particles.
