Reactor Noise Experiments by Using Acquisition System for Time Series Data of Pulse Train

Abstract

An acquisition system for the time series data of a pulse train was developed to perform the reactor noise experiments. Using this acquisition system, some important reactor kinetic parameters can be obtained by using various data analysis methods for the reactor noise experiments, which facilitates to achieve new experimental knowledge about characteristics of them proposed so far through direct comparison among the results of various methods. In the present study, the prompt neutron decay constant α_pat two near delayed critical states of a core constructed in the Kyoto University Critical Assembly were measured by four well-known data analysis methods; the Feynman-α, the Rossi-α (Type-I and Type-II) and the frequency analysis methods. The results showed that ap values measured by the Type-I Rossi-α and the frequency analysis methods agreed with those by the Feynman-α method considering both effects of the delayed neutrons and the counting loss of neutron counter, whereas it was impossible to obtain the adequate α_p values by the Type-II Rossi-α method. Moreover, it was demonstrated that one cannot neglect both effects for the measurement of α_p by the Feynman-a method, whereas those by the Type-I Rossi-a and the frequency analysis methods hardly suffered.

KEYWORDS:

• time series data
• pulse train
• reactor noise
• experiment
• KUCA
• Feynman-α method
• Rossi-α method
• frequency analysis method
• prompt neutron decay constant
• delayed neutrons
• counting loss
• subcriticality monitor