Gamma-ray imaging as a tool for uranium processing plants

摘要

Gamma-radiation is frequently used as an analysis and characterization signal to monitor material in the nuclear fuel processing cycle. The selection as a diagnostic is self-evident since the radiation is ubiquitous, characteristic of the isotopes present, and sufficiently penetrating so that measurements may be made remotely. However, save through detector proximity or minimal collimation, the directional nature of the radiation is generally not used in traditional nondestructive assay (NDA) measurements. To demonstrate the additional information available, we used GRIS, the Gamma-Ray Imaging Spectrometer, at the K-25 and Portsmouth gaseous diffusion plants. In this facility, UF(sub 6) gas is enriched in heated equipment and piping which run inside an insulated housing. Occasionally, the process develops uranium deposits due to leakage of wet air or environmental changes within the housing that cause solidification of the process gas. When such deposits occur, traditional NDA techniques frequently require costly and time-consuming entry within the heat shielding to obtain precise information on the deposit unavailable from outside the shielding. In this paper we discuss GRIS, the gamma-ray imaging technique it uses, and present the results of measurements obtained on fuel processing equipment.