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

A 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 a Multi Channel Scaler (MCS) system, and it has been applied for the monitoring of steady or slowly varying sub-critical reactivity using a 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 the 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.