A FPGA based digital reactivity meter for THOR research reactor

A field programmable gate array (FPGA) based real-time reactivity-meter for Tsing-Hua Open-Pool Reactor (THOR) has been developed. The reactivity meter can operate online with real time calculation. According to the inverse point reactor dynamics model, reactivity was estimated from the measured power data. In order to improve the accuracy on the estimation, sensitivity studies have been made to determine a proper sample time interval to reduce the fluctuation of the measured power data. Two sets of ADC were used to extend the dynamic range of the monitoring system. Compared with the existing analog system, the digital system has a wider dynamic range, less noise in low power range, and a comparable system response time.