RADIOLOGICAL ASPECTS OF CYCLOTRON DECOMMISSIONING

In this paper, the radiological and economic issues of dismantling cyclotrons of various types, the accumulation of radionuclides in the details of the cyclotron itself, and the activation of the walls of the cyclotron bunker due to the capture of secondary neutrons are considered. As a result of (n,γ)-reactions on thermal neutrons, radionuclides 152Eu, 60Co, 46Sc are formed in the concrete of the cyclotron bunker with a half-life of 2,6 to 14 years and an activity of 0,1–11 kBq/kg. The maximum of their distribution usually lies at a depth of 10–15 cm. In the details of the cyclotron and the metal infrastructure of the bunker, the main radionuclides are 54Mn, 57Co, 65Zn. The analysis of the accumulation of long-lived radionuclides is of great importance for the design of new cyclotron facilities in order to ensure radiation safety and storage of radioactive waste and, as a result, to minimize the radiation exposure of personnel during the dismantling of the cyclotron.