Measurement of varying sub-critical reactivity with digital time-series data acquisition system using difference filter technique

Digital Time-Series Data Acquisition System has been developed for the monitoring of sub-critical reactivity. The system registers arriving time of the signal from a neutron detector as digital data in a FIFO (First In First Out) memory module, and the time data is read and stored by PC (Personal Computer). This system can measure time series data more efficiently than conventional Multi Channel Scaler (MCS) system, and it has been applied for the monitoring of steady or slowly varying sub-critical reactivity using conventional Feynman-α method. In the present work, this system was applied for the monitoring of rapidly varying sub-critical reactivity using the difference filter technique. The test experiment was carried out with a research reactor of Atomic Energy Institute in Kinki University. From the result, it was shown that the present system is useful for the monitoring of rapidly varying sub-critical reactivity by application of the difference filter technique.