We report on the development of the Kuosheng plant analyzer on an AD100 peripheral processor system for the Kuosheng nuclear power station and on benchmarking against plant data recorded during power tests. The Kuosheng plant analyzer was developed based on the Taiwan Power Company’s Chinshan plant analyzer with minor modifications. The modifications include revision of models, preparation of an input deck, and regeneration of the plant-specific tables. The simulation speed of the Kuosheng plant analyzer is six times faster than real time. Also, the self-initialization algorithm and optimization module provide more convenient simulation. Three power test transients were simulated and benchmarked against plant data. Comparison results show good agreement with plant data. The plant-specific component models were written as modular models, so that the Kuosheng plant analyzer can be easily modified for other boiling water reactor plants.