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KMID : 0357520210440040359
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Journal of Radiological Science and Technology
2021 Volume.44 No. 4 p.359 ~ p.365
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Comparative Evaluation of Radioactive Isotope in Concrete by Heavy Ion Particle using Monte Carlo Simulation
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Bae Sang-Il
Cho Yong-In
Kim Jung-Hoon
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Abstract
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A heavy particle accelerator is a device that accelerates particles using high energy and is used in various fields such as medical and industrial fields as well as research. However, secondary neutrons and particle fragments are generated by the high-energy particle beam, and among them, the neutrons do not have an electric charge and directly interact with the nucleus to cause radiation of the material. Quantitative evaluation of the radioactive material produced in this way is necessary, but there are many difficulties in actual measurement during or after operation. Therefore, this study compared and evaluated the generated radioactive material in the concrete shield for protons and carbon ions of specific energy by using the simulation code FLUKA. For the evaluation of each energy of proton beam and carbon ion, the reliability of the source term was secured within 2% of the relative error with the data of the NASA Space Radiation Laboratory(NSRL), which is an internationally standardized data. In the evaluation, carbon ions exhibited higher neutron flux than protons. Afterwards, in the evaluation of radioactive materials under actual operating conditions for disposal, a large amount of short-lived beta-decay nuclides occurred immediately after the operation was terminated, and in the case of protons with a high beam speed, more radioactive products were generated than carbon ions. At this time, radionuclides of 44Sc, 3H and 22Na were observed at a high rate. In addition, as the cooling time elapsed, the ratio of long-lived nuclides increased. For nonparticulate radionuclides, 3H, 22Na, and for particulate radionuclides, 44Ti, 55Fe, 60Co, 152Eu, and 154Eu nuclides showed a high ratio. In this study, it is judged that it is possible to use the particle accelerator as basic data for facility maintenance, repair and dismantling through the prediction of radioactive materials in concrete according to the cooling time after operation and termination of operation.
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KEYWORD
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FLUKA, Heavy ion Accelerator, Neutron, Activation product, Bragg peak
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