PRELIMINARY ANALYSES FOR ACCELERATOR-DRIVEN SYSTEM WITH HIGH-ENERGY PROTONS IN KYOTO UNIVERSITY CRITICAL ASSEMBLY

摘要

At the Kyoto University Research Reactor Institute, the first injection of spallation neutrons generated by the high-energy proton beams into a reactor core was accomplished on 4th March, 2009. Using 3 detectors which located at near active core regions, the prompt and delayed neutron behaviors by proton injection are experimentally observed and the neutron beam characteristics at the beam duct are also watched by Gafchromic films. Under the subcritical condition with 0.76 %Ak/k, an In wire irradiation experiment is accomplished horizontally. The "5In(n, y)"6mIn reaction rate comparison is also performed by MCNPX simulation and its errors shows within the allowance of the experimental statistical errors. By numerical analysis, the feasibility of neutron shield and beam duct is verified and the performance change inside of critical assembly is investigated. Finally, it is confirmed that the effect of different injected proton energy is not intensified because of well-thermalized KUCA core condition by sufficient polyethylene moderators and reflectors.