United States Nuclear Regulatory Commission - Protecting People and the Environment


The use of sealed sources of ionizing radiation for nondestructive examination of the structure of materials. When the radiation penetrates the material, it produces a shadow image by blackening a sheet of photographic film that has been placed behind the material, and the differences in blackening suggest flaws and unevenness in the material.

Page Last Reviewed/Updated Monday, June 22, 2020