Analysis of the Causes of Irregular 36Cl Radionuclide Distribution in Irradiated Nuclear Graphite

• Published in: Surface investigation, x-ray, synchrotron and neutron techniques x-ray, synchrotron and neutron techniques, 2020, Vol.14 (1), p.176-183
• Main Authors: Bespala, E. V., Pavlyuk, A. O., Kotlyarevskiy, S. G., Novoselov, I. Yu
• Format: Article
• Language: English
• Subjects: Chemistry and Materials Science; Graphite; Heterogeneity; Materials Science; Neutron flux; Nuclear engineering; Nuclear reactors; Nuclear safety; Radioisotopes; Reaction products; Surfaces and Interfaces; Thermodynamic equilibrium; Thermodynamic models; Thin Films; Uranium; Waste disposal
• ISSN: 1027-4510; 1819-7094
• DOI: 10.1134/S1027451020020056

— The article is dedicated to analyzing the concentration processes of the long-lived 36 Cl radionuclide in irradiated graphite of uranium-graphite nuclear reactors. The 36 Cl radionuclide is one of the most important isotopes for assessing the safety of radioactive-waste disposal. An analysis of the so-called Nugget effect due to the substantial heterogeneity of the 36 Cl content in samples of irradiated graphite of nuclear reactors is carried out. In the same graphite elements, the difference in the 36 Cl concentration reaches 100 times regardless of operational factors, such as the neutron flux and temperature. The article discusses the main processes that can affect 36 Cl contamination in irradiated graphite. Particular attention is paid to determining the form of 36 Cl in graphite, taking into account the features of its manufacturing and thermodynamic modeling of the equilibrium compositions of reaction products during the purification of unirradiated graphite in a gaseous medium.