Evaluation of reaction rate distribution for shielding region in the prototype fast reactor Monju

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

The reliability and usefulness of the reaction rate distribution data measured in the prototype fast breeder reactor Monju were examined through a comparison with a calculation using JENDL-4.0, mainly focusing on shielding regions around the reactor core. The U(n,f) and Ni(n,p) reaction rates sensitive to high-energy neutrons were all judged reliable. The calculation-to-experiment values are slightly worse in the shielding regions, where those for the Ni(n,p) reaction rates were improved by employing JEFF-3.3 instead of JENDL-4.0. A different tendency was observed between the two reactions, probably due to the U(n,f) cross section in the energy range of around 700 eV. The reaction rates of U(n,f), Pu(n,f), U(n,), and Au(n,) sensitive to the lower energy neutrons were mostly judged reliable. The data in the lower shielding region are less reliable but acceptable for the shielding calculation.