Macroscopic cross section measurements and defect detection in materials using neutron radiography technique

Neutron radiography (NR) technique was applied to analyze behaviors of thermal neutrons in slabs, which have a wide range of the ratio r, of scattering to non-scattering cross sections. Transmittances were measured for various materials as basic data for NR study. Scattering components were estimated and subtracted from observed neutron intensities measured behind slabs. Effective total macroscopic cross sections were estimated and were found they agreed with given values of ASTM E748-80 within ±20%. Defects (voids and impurities) were also analyzed, and their detection limits for thickness t were estimated for materials of various r as a function of t.