Presentation Investigation of Mo-99 Radioisotope Production by d-Li Neutron Source

太田, 雅之  ,  権, セロム  ,  佐藤, 聡  ,  落合, 謙太郎  ,  鈴木, 寛光

An advanced fusion neutron source (A-FNS) is under planning at Rokkasyo in Japan. The A-FNS has an accelerator providing a 40 MeV deuteron beam of 125 mA and the Li target. It produces a large amount of neutrons due to Li(d,n) reaction, and has the neutron flux of about 6*10^14 n/cm^2/s at the back plate of the Li target with a broad energy peak around 14 MeV. The main purpose of the A-FNS is the fusion material irradiation. In addition, we propose a production of radioisotopes for medical application. We examine a production of Mo-99. It is the parent nucleus of Tc-99m, which is the used in the nuclear medicine diagnosis. The Mo-99 used in Japan are supplied only from nuclear reactors in foreign countries. The domestic production of Mo-99 is required because of the avoidance of the risk of the supply disruption. A new production method has been proposed for Mo-99, and it applies the Mo-100(n,2n)Mo-99 reaction with accelerator. We have estimated that the A-FNS has an enough potential to produce Mo-99 over its demand in Japan from the Mo-100(n,2n)Mo-99 reaction. In addition, we show the usefulness of the Mo-98(n,g)Mo-99 reaction by the usage of the natural molybdenum from the viewpoint of economic efficiency. In this study, we conduct the conceptual design study of the radioisotope production module at A-FNS which has spectrum shifters and neutron reflectors composed of graphite and beryllium through analyses of the production of Mo-99. The spectrum shifter moderates fast neutrons to lower energy neutrons. It increases the production of Mo-99 due to the Mo-98(n,g)Mo-99 reaction, while it decreases that due to the Mo-100(n,2n)Mo-99 reaction. The neutron reflector increases both of fast and low energy neutrons at the samples. We design the spectrum shifters and reflectors in order to achieve the maximum of the amount of the production of Mo-99. We apply the Monte Carlo transport code MCNP5 and D-Li neutron source code McDeLicious-11 in the calculation. We establish the conceptual design of the radioisotope production module. We compare the amount of the production of Mo-99 with this module at A-FNS with the demand in Japan, and show the usefulness of this module.
18th International Conference on Fusion Reactor Materials

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