Atsushi Fushimi

Plant Simulation System for Developing ABWR Automatic Power Regulator System

We developed a plant simulation code system to design and verify an automatic power regulator (APR) system for an advanced boiling water reactor (ABWR). The point kinetic plant simulator AUTSIMU is an off-line and real-time online plant simulation code that can simulate the start-up process from a subcritical condition of cold water to a 100% rated power condition as well as the reactor shutdown process. The three-dimensional effect of neutron detector signals in the core was simulated by combining predetermined three-dimensional analysis and point kinetic analysis results. The AUTSIMU code was tested using ABWR start-up experimental data. The calculated results were in good agreement with the measured ones. Less than one minute was needed in the off-line mode to simulate a ten-hour transient with an ordinary personal computer. We confirmed that simple AUTSIMU models could effectively simulate ABWR start-up behaviors. The APR hardware was effectively verified in the online mode through factory tests before being shipped to the nuclear site.

Development of Instrumentation System for Severe Accidents

The accident at Tokyo Electric Power Company’s Fukushima Dai-ichi Nuclear Power Plant (TF-1 accident) caused severe situations and resulted in a difficulty to measure important parameters to monitor plant conditions. Therefore, we have studied to select the important parameters (SA parameters) that should be monitored at the severe accident and are developing the Severe Accident Instrumentations and Monitoring Systems (SA-keisou) that could measure the parameters in severe accident conditions. (SA-keisou in Japanese means “severe accident instrumentation and monitoring systems). In this study, the boiled water reactor (BWR) is mainly explained.This study is a part of the results of the collaborative project by domestic electric power companies and plant manufacturers that is carried out as the Safety Enhancement for LWRs program by Agency for Natural Resources and Energy.Copyright