Nuclear reactor noise analysis experiment using a time series data measurement system

A time series data measurement system to obtain time information of a pulse series was developed, and measurement of nuclear reactor noise using the system was carried out in KUCA (Kyoto University Critical Assembly). And, four analysis methods, the Feynman-alpha method, Rossi-alpha method (Type-1, Type-2), and frequency analysis method, were compared through the measurement of prompt neutron attenuation constant αp in delayed critical state. The results proved that αp values obtained by the Feynman-alpha method, the Type-1 method and the frequency analysis method agree each other, but αp values can not be evaluated by the Type-2 method. Also, while αp values are liable to existence of delayed neutron and dead time of a detector in the Feynman-alpha method, it is not so in the Type-1 method and the frequency analysis method. (M.M.)