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

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

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.