Evaluation of reaction rate distribution measurement in the prototype fast reactor Monju

もんじゅ炉内反応率分布測定試験の評価

大釜 和也   ; 羽様 平 ; 片桐 寛樹*; 竹越 淳*; 毛利 哲也 

Ohgama, Kazuya; Hazama, Taira; Katagiri, Hiroki*; Takegoshi, Atsushi*; Mori, Tetsuya

もんじゅ性能試験では、Puなどの核分裂率反応率分布やUの捕獲反応率分布が箔放射化法により測定されている。炉心と径ブランケット領域の反応率分布測定値の最確値を算出し、再現解析値との比較により高速炉設計手法の検証データとしての適用性を評価した。集合体中心での歪を適切に補正する解析モデルを導入するなどの工夫の結果、対象としたデータはすべて信頼でき、数%の精度で検証データとして使用できることを確認した。Uの捕獲反応率については、箔の実効断面積の計算に箔自身と箔周辺の燃料の共鳴断面積を考慮する必要がある。

In the prototype fast breeder reactor Monju, reaction rate distributions of fission reaction rates of Pu, U and U, and capture reaction rate of U were measured by using activation foils during its system startup test. The measurements in the core and radial blanket regions were evaluated in detail, and their reliability and usefulness as the validation data for fast reactor neutronics design methodologies were examined through a comparison with calculations. The reaction rate data measured in Monju were confirmed all reliable and useful as the validation data. The fission reactions of Pu, U, and U can be validated with an accuracy of a few percent in the core and blanket regions. The capture reaction of U in the core region also can be validated with a similar accuracy, whereas a precise calculation of the foil cross section is necessary to consider resonance shielding effects of surrounding fuel pins and a foil.