出力の漸近的挙動に基づく反応度評価

Reactivity estimation based on asymptotic behavior of power in subcritical state

山根 祐一  

Yamane, Yuichi

核燃料施設においては核燃料溶液の臨界管理されていない容器への流入、原子炉では燃料の装荷や制御棒引き抜き、福島第一原子力発電所では燃料デブリ取出しや準備のための水張りなどを想定し、未臨界の核燃料の反応度が変化した後に生じる出力の漸近挙動を反応度の関数として表す方程式を、一点炉動特性方程式に基づいて導出した。この出力漸近挙動を表す方程式を利用して反応度を評価する手法を開発し、実験データに適用してドル単位の反応度を誤差程度以下で評価できる見通しを得た。

In the condition such as erroneous transport of nuclear fuel solution in fuel reprocessing plant, criticality approach in reactor and critical assembly, the retrieval work of fuel debris in FUKUSHIMA DAI-ICHI, and so on, in which an amount of reactivity is inserted into nuclear fuel in a subcritical state, an equation is derived which relates the total reactivity to the asymptotic behavior of the power based on one-point kinetics equation. Based on the new equation, a reactivity measurement method has been developed. The method was applied to an experimental data to find that the difference between the experimental and estimated reactivities was 4%.