Transmutation of LLFP by Irradiation of Neutrons on Muon Catalyzed Fusion (MCF) Reactor

The objective of this article is to provide a database for the transmutation of LLFP (long-lived fission products) using neutrons of muon-catalyzed nuclear fusion (MCF). As examples of LLFP with a natural half-life of more than 105 years, four nuclides, 107Pd, 135Cs, 79Se and 93Zr, are chosen. Taking simplified geometrical models of the neutron source and blanket, which appear in the conceptual design of in-flight MCF, the nuclide production yield was calculated by a three-dimensional Monte Carlo calculation based on nuclear data. The number of neutrons and flux, which are necessary to convert half of the initial LLFP amount into a stable nucleus, are obtained. We also investigated the method of controlling two competing reactions of the nuclear fractions by fast neutrons,called the (n, 2n) reaction, and the neutron captures of the thermal neutrons. Theoretical simulation studies have revealed the quantity of LLFP that is detoxified by transmutation under the condition that the fusion neutrons are continuously irradiated to LLFP for approximately 10 years with a flux of 1019 m−2 s−1.