Activation γ-spectrometric method of determining the mass of samples of nuclear materials

Abstract

The possibility of using activation γ-spectrometry to determine the mass content of nuclear materials in matter is investigated. Irradiation of samples for a short time with moderated neutrons from a ~107 sec–1 Pu–Be source is used to induce 1436 keV γ-ray emission from 138Cs. These γ-rays are suitable for measurements; the mass of the nuclear materials is determined from the intensity of the radiation. Three series of experiments are performed with sets of samples consisting of uranium and uranium dioxide with different mass and degrees of enrichment. Experiments showed that the error in determining the mass of uranium samples can reach 1–3% with 30–60 min irradiation and the same measurement duration. Special experiments were performed to investigate the influence of the experimental geometry and the self-absorption of the γ rays in the sample, which limit the possibility of γ-spectrometric measurements on samples of nuclear materials. The activation γ-spectrometric method can be used for analyzing metallic uranium samples, powder samples, samples of fuel micropellets and uranium hexafluoride, and plutonium samples.