Comparative analysis of a fission product behavior during severe accidents for a typical PLWR and PHWR

The fission product behaviors of a severe accident sequence were analyzed for the typical pressurized light water reactor (PLWR) and heavy water reactor (PHWR) operated in Korea. The OPR-1000 and the Wolsong-2 plant were selected as reference plants. The obtained results are for: (1) the fission product release from the core, (2) the fission product distributions in a reactor coolant system, a molten corium, a reactor vessel, or a containment building, (3) the fission product release from the containment. The thermal hydraulic, severe accident phenomenological, and radiological analyses for their evaluation have been performed by using the MAAP(Modular Accident Analysis Program) and ISAAC (Integrated Severe Accident Analysis Code for CANDU Plant) computer program. Based on the ISAAC and MAAP calculation, the results show that the accident progression, including the fission product transportation, of the CANDU-6 type reactor is much more delayed than the typical PLWR, however, the possibility of a fission product release to the environment can be earlier due to the lower reactor building design pressure. (author)