|発明の名称||METHOD FOR MEASURING COMPOSITION, SUBCRITICALITY, DELAYED NEUTRON RATIO, NEUTRON GENERATION TIME, AND PROMPT NEUTRON LIFESPAN OF NUCLEAR FISSILE MATERIAL ON THE BASIS OF ONLY SIGNALS OF NEUTRON DETECTOR AND THE LIKE|
PROBLEM TO BE SOLVED: To provide a method and device using the method that allow reactivity to be properly measured even in a situation where information on an inner structure of a nuclear fuel body system such as, for example, a post-incident nuclear reactor, or an entire shape thereof is not obtainable.
SOLUTION: Using that n(t)=αq(t)+n∞ of an expression is established where the number of neutrons, to be detected by a neutron detector, at a time t in a nuclear fuel is denoted as n(t), the number of neutrons when the neutron remains stable after a change in reactivity and the like is denoted as n∞, a coefficient of subcriticality is denoted as αy, and a weighted time differential n*(t) of the number of neutrons n(t) is denoted as q(t), and a ratio of αyq and n - n∞ (a difference between n serving as a calculation rate deducting a noise component from a neutron detection signal and a value n∞ at a stable time of the neutron stands at 1 regardless of the time, a delayed neutron ratio and a delayed neutron decay constant are determined.
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