ABSTRACT
The containment atmosphere would consist of steam, air, hydrogen, some hydrocarbons, aerosol material, other fission products in various chemical forms, and the iodine species. To fill the large gaps in knowledge and to provide a means for assaying the iodine source term, the chapter has proceeded along two paths: Experimental studies of the chemical behavior of iodine under containment conditions and Development of Transport and Retention of Nuclides in Dominant Sequences (TRENDS), a computer code for modeling the behavior of iodine in containment and its release from containment. The main body of the chapter consists of a description of TRENDS. These two parts to the program are complementary in that models within TRENDS use data that were produced in the experimental program; therefore, these models are supported by experimental evidence that was obtained under conditions expected in severe accidents. TRENDS has been designed as a detailed mechanistic code to calculate iodine behavior in containment.
