Study of irradiated graphite-bakelite paste

Abstract

Abstract The article is devoted to the study of irradiated graphite-bakelite paste formed during the restoration of graphite stack and the operation of uranium-graphite reactors. It was shown that irradiation of graphite-bakelite paste in the reactor leads to the formation of long-lived radionuclides and the accumulation of Wigner energy. The studies of graphite-bakelite paste extracted from the graphite stack of one of the UGR with a closed primary loop showed that the samples of graphite-bakelite paste are contaminated unevenly with 137Cs, 154Eu, 60Co, and 241Am radionuclides (fission and activation products and actinides). From the results of experiments on leaching of radionuclides from graphite-bakelite paste, it can be seen that radionuclides 241Am and 137Cs are more subjected to leaching. The estimation of the stored energy in the selected samples shows that the heat release begins at a temperature of 600–650 ◦C. The largest amount of stored energy is released at a temperature of 750 ◦C. Moreover, the magnitude of this quantity does not exceed 1–6 J/g. It was also shown that the development of the concept and program for decommissioning of UGR, the stack of which was restored using graphite-bakelite paste, requires additional studies to determine the potential danger of irradiated graphite-bakelite paste.