Validation of COCOSYS 2.4v4 AIM module on various single effect and integral experiments

Nuclear power plant containment is the last barrier, as stated in the worldwide accepted in-depth safety principle, between a nuclear reactor and the environment. During various accident scenarios, fission products can exit the fuel and primary circuit, entraining the containment and later the environment. One of the most important fission products exiting the corrupted fuel pins is iodine. Iodine is a strongly bioactive chemical species with a very complex in-containment physical-chemical behavior. The fission product transport inside the containment as well as the release into the environment takes an important role in the preliminary safety analysis report (PSAR). Analyses presented in PSAR are calculated by numerous computational codes. The validity of these results should be checked. The only chance to do so is to validate the computational tool on validation experiments, which represent single effect behavior as well as a complex behavior on integral tests. Validation experiments presented in this paper are from an international Behavior of Iodine Project (BIP) which was conducted under the Organization for Economic Co-operation and Development – Nuclear Energy Agency (OEC-NEA). The single effect tests are illustrated by four representative experiments, namely the G-01 studying the iodine deposition and resuspension on steel coupon in gas phase, the G-04 studying the iodine deposition and resuspension on painted surface in gas phase, the G-06 studying the humidity effect on iodine deposition on painted coupons in gas phase and finally the AECL-2 studying the iodine deposition on painted coupons in water phase. The integral test is represented by the RTF P9T1, where the complex iodine chemistry including the response to pH change is studied. The scope of this paper is to reveal whether the COCOSYS code is capable to bring satisfactory results of a complex in-containment iodine behavior with recommended and basic setup of computational models and parameters.