Analytic initialization of nonequilibrium iodine and xenon distributions for core transient simulation

In a core transient simulation, the initial condition of the simulation should be consistent with the real core state. The initial iodine and xenon distributions, which cannot be measured in the core, have significant effects on the transient with xenon dynamics of a pressurized water reactor. In simulating the transient starting from a nonequilibrium xenon state, accurate initialization of the nonequilibrium iodine and xenon distribution is essential to predict the core transient behavior. An initialization method that uses the iodine and xenon states to predict a core transient starting from a nonequilibrium xenon condition is developed through the analytical treatment of the relationship between power and the iodine and xenon distributions. An application of this method tr;provided by simulating a transient in the start-up test of Yonggwang Unit 3.