[en] Core management code POLESTAR has been developed by PNC and it has enough functions for core management. The code has been successfully used to carry out core management of Fugen such as making a long term or next cycle fuel loading plan, predicting detailed characteristics of a next cycle core, planning of a control rod pattern and evaluating the core life time after reactor start-up and so on. This code has been contributed to the reliable and economical operation of Fugen, since its accuracy has been checked and the code has been tailored by comparing its calculation results with various measured data. (author)