A study on radial buckling correction for improved ECP estimation using APOLLO

The accurate Estimation of Critical Position (ECP) is required to reduce radio waste and plant outage time in nuclear plant. They key factor for the calculation of ECP is the best prediction of xenon worth at the time of startup. Also the control rod worth shoud be considered since control rods are usually inserted into the core in order to achieve the criticality of nuclear reactor. Current methodology for the calculation of ECP is based on the results from 3D diffusion codes for the reference core status, like HFP ARO equilibrium xenon conditon. However due to the lack of information about the operational history, it is very difficult to predict the ECP correctly in the presence of xenon. Thus, in this study the methodology to predict the ECP using the one-dimensional diffusion code considering the operational history is presented and also correction factors are introduced to match with the result of 3D code