Recent tendency to neutron beam experiments

The application of neutron beam experiment to the study of reactor materials is described in this paper. In Japan, neutron beam experiments have been developed, using reactors JRR-2, JRR-3 and KUR-1. Most of experimental apparatuses in Japan are neutron diffraction systems and three-axis neutron spectrometers, similarly to those in U.S.A. and Canada. In Europe, cold neutron experiments have been developed. The most interesting experiment at present is the small angle scattering experiment. This technique can be applied to the other field than solid state physics. Nondestructive measurements for large samples can be made. Measurement while controlling outside conditions, and measurement for radioactive substances of considerable intensity are possible. Statistical mean values for larger volumes can be obtained as compared with electron microscope observation. Effects of multiple scattering are negligible. A non-destructive test of the properties of turbine blades was made at the GALILEO research reactor. The results were useful for the estimation of the residual life of the blades. Anomaly in the welded parts of pressure vessels for reactors can be detected by the small angle scattering method. The voids in irradiated samples were also observed by this technique. (Kato, T.)