Evaluation of fixed absorber reactivity measurement in the prototype fast reactor Monju

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

In the prototype fast breeder reactor Monju, fixed absorber worth was measured as a difference of core reactivity measured by control rod worth between cores with and without a single or three fixed absorbers. In the present paper, the measurements were evaluated in detail and its reliability and usefulness as a validation data were investigated through a comparison with calculations using the latest neutronics design methodology developed in Japan Atomic Energy Agency. Calculated-to-experiment values (C/Es) and their uncertainties of fixed absorber worth were 1.000.05 and 1.020.04, respectively. Through this study, the measurements and calculations were found consistent and reliable.