Prediction accuracy improvement of neutronic characteristics of a breeding light water reactor core by extended bias factor methods with use of FCA-XXII-1 critical experiments

Kugo, Teruhiko ; Ando, Masaki  ; Kojima, Kensuke; Fukushima, Masahiro   ; Mori, Takamasa; Nakano, Yoshihiro ; Okajima, Shigeaki  ; Kitada, Takanori*; Takeda, Toshikazu*

The effectiveness of the extended bias factor methods, the LC and PE methods, is numerically investigated by applying them to a breeding light water reactor core as a target core with use of FCA-XXII-1 critical experiments. The present study numerically verifies the features of the extended bias factor methods. Both the methods can improve the prediction accuracy the most by using all the experiments. The PE method always improves the prediction accuracy with any combination of experiments. The PE method is always superior to the LC method for improvement of the prediction accuracy. From the present study, the followings are found. The experiments on multiplication factor are more applicable to a reaction rate ratio of U capture to Pu fission (C28/F49) of the target core than the experiments on C28/F49. Combinations of the experiments on multiplication factor is more effective to a void reactivity of the target core than those of the experiments on void reactivity though those on void reactivity are superior to those on multiplication factors in the case of using a single experiment. From these results, we conclude that the experiments on multiplication factor are more effective than the other experiments for all the neutronic characteristics of the target core. From these results, it is concluded that the PE method is promising to complement full mockup experiments for various future nuclear systems by using a number of existing and future benchmark experiments.