STUDY ON NEUTRON REACTION CROSS SECTIONS OF IMPORTANT FISSION PRODUCTS

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Accurate neutron reaction cross sections of important fission products are needed to develop an innovative nuclear reactor which aims at very high burn-up of fuel or incineration of transuranic elements. The purposes of the present study are to accurately measure capture cross sections, capture gamma-ray spectra, and inelastic scattering cross sections of Nd-143,145 and Sm-147,150 in an incident neutron energy region of 10 to 800 keV,to theoretically analyze the mesured results, to investigate not only the present results but also the current results of Ce-140, Pr-141, Sm-148,149,152,154, and Dy-161,162,163, and to elucidate the mechanisms of neutron capture and inelastic scattering by important fission products.The results of the present study are summarized as follows :1. The capture cross sections, capture gamma-ray spectra, and inelastic scattering cross sections of Nd-143,145 and Sm-147,150 were measured with the error of about 5% in an incident neutron energy region of 10 to 800 keV.2. It was found that a statistical model calculation could reproduce the measured capture cross sections and capture gamma-ray spectra of the four nuclides.3. It was found that the inelastic scattering cross sections of the four nuclides could be reproduced by a statistical model calculation plus a direct model calculation with a distorted-wave Born approximation.4. It is the next problem to elucidate the mechanisms of neutron capture and inelastic scattering by important fission products after investigating not only the experimental and theoretical results of the four nuclides but also the current results of other nuclides.