Understanding of Iodine Behavior Model Under Severe Accident Conditions in NPPs (I)

Support from ISAAC code which is developed in Korea will be needed when a regulatory body (KINS) reviews Wolsong specific SAMG submitted by KHNP in late 2009. The SA research area can be divided into thermal hydraulic (T/H) and fission product (FP) areas and international evaluation shows an increasing opinion that past analysis has large uncertainty in the FP area. Using very small manpower (less than 0.5 MY for 3 year period (2007.3-2010.2)), this study reviewed EU results (BIP, ThAI) and ISAAC possibility for experiment simulation. As results, international and domestic technical status until early 2009 was investigated and input model modification based on these investigation was provided. Simulation possibility of EU experiments showed the Benchmark function in MAAP should be activated in ISAAC (by cooperation with MAAP developer, FAI) as a preliminary arrangement and independent model development reflecting those international results could be possible. This documentation will be referred from PHWR analysis for both source term and safety goal and will enhance the internal understanding for the necessity of iodine behavior study under SA conditions. FP (mainly iodine) model development in the next step using this study will contribute to keeping both improved quality and international competitiveness in ISAAC code