NEUTRON RADIOGRAPHIC INSPECTION OF HEAVY METALS AND HYDROGENOUS MATERIALS

The possibility of using thermal-neutron radiography for inspecting heavy metals and hydrogenous materials was examined. The data include exposure curves, contrast sensitivities, and an assessment of the influence of higher energy neutrons and interfering gamma radiation on image quality. It is shown that, in the case of homogeneous materials, neutron radiography presents definite advantages for the inspection of heavier metals such as uranium, bismuth, and lead, and that the images obtained in such inspections are influenced very little by other radiation in the thermal-neutron beam. This is somewhat less true for intermediate metals such as steel and tungsten, although in these cases too, some exposure time advantage can usually be gained. Nevertheless, neutron radiographic inspection of these intermediate materials may be limited to those cases in which some complication, such as radioactivity of the sample, is involved. Thermal-neutron inspection of hydrogenous materials having a thickness greater than about an inch is not recommended and may be useful primarily in special cases such as one in which the light material is in some combination with a heavier, x-ray absorbing material. (auth