Chapter 15
Development of Uranium-Free TRU
Metallic Fuel Fast Reactor Core
Kyoko Ishii, Mitsuaki Yamaoka, Yasuyuki Moriki, Takashi Oomori,
Yasushi Tsuboi, Kazuo Arie, and Masatoshi Kawashima
Abstract A TRU-burning fast reactor cycle associated with a uranium-free transuranium (TRU) metallic fuel core is one of the solutions for radioactive waste
management issue. Use of TRU metallic fuel without uranium makes it possible to
maximize the TRU transmutation rate in comparison with uranium and plutonium
mixed-oxide fuel because it prevents the fuel itself from producing new plutonium
and minor actinides, and furthermore because metallic fuel has much smaller
capture-to-fission ratios of TRU than those of mixed-oxide fuel. Also, adoption of
metallic fuel enables recycling system to be less challenging, even for uranium-free
fuel, because a conventional scheme of fuel recycling by electrorefining and
injection casting is applicable.
There are some issues, however, associated with a uranium-free TRU metallic
fuel core: decrease in negative Doppler reactivity coefficient from the absence of
uranium-238, which has the ability to absorb neutrons at elevated temperatures,
increase in burn-up swing, because fissile decreases monotonically in uranium-free
core, and so on. The purpose of this paper is to evaluate the feasibility of the
uranium-free TRU metallic fuel core by investigating the effect of measures taken
to enhance Doppler reactivity feedback and to reduce burn-up swing. The results
show a TRU-burning fast reactor cycle using uranium-free TRU metallic fuel is
viable from the aforementioned points of view because the introduction of diluent
Zr alloy, spectrum moderator BeO, and lower core height enables Doppler reactivity coefficient and burn-up reactivity swing of uranium-free TRU metallic fuel to be
as practicable as those of conventional fuel containing uranium.
Keywords Burn-up swing • Doppler reactivity feedback • Fast reactor • Metallic
fuel • Trans-uranium • Uranium-free
K. Ishii • M. Yamaoka • Y. Moriki • T. Oomori • Y. Tsuboi • K. Arie (*)
Toshiba Corporation, 8 Shinsugita-Cho, Isogo-Ku, Yokohama 235-8523, Japan
e-mail: kazuo.arie@toshiba.co.jp
M. Kawashima
Toshiba Nuclear Engineering Service Corporation, 8 Shinsugita-Cho, Isogo-Ku,
Yokohama 235-8523, Japan
© The Author(s) 2015
K. Nakajima (ed.), Nuclear Back-end and Transmutation Technology for Waste
Disposal, DOI 10.1007/978-4-431-55111-9_15
155
Development of Uranium-Free TRU
Metallic Fuel Fast Reactor Core
Kyoko Ishii, Mitsuaki Yamaoka, Yasuyuki Moriki, Takashi Oomori,
Yasushi Tsuboi, Kazuo Arie, and Masatoshi Kawashima
Abstract A TRU-burning fast reactor cycle associated with a uranium-free transuranium (TRU) metallic fuel core is one of the solutions for radioactive waste
management issue. Use of TRU metallic fuel without uranium makes it possible to
maximize the TRU transmutation rate in comparison with uranium and plutonium
mixed-oxide fuel because it prevents the fuel itself from producing new plutonium
and minor actinides, and furthermore because metallic fuel has much smaller
capture-to-fission ratios of TRU than those of mixed-oxide fuel. Also, adoption of
metallic fuel enables recycling system to be less challenging, even for uranium-free
fuel, because a conventional scheme of fuel recycling by electrorefining and
injection casting is applicable.
There are some issues, however, associated with a uranium-free TRU metallic
fuel core: decrease in negative Doppler reactivity coefficient from the absence of
uranium-238, which has the ability to absorb neutrons at elevated temperatures,
increase in burn-up swing, because fissile decreases monotonically in uranium-free
core, and so on. The purpose of this paper is to evaluate the feasibility of the
uranium-free TRU metallic fuel core by investigating the effect of measures taken
to enhance Doppler reactivity feedback and to reduce burn-up swing. The results
show a TRU-burning fast reactor cycle using uranium-free TRU metallic fuel is
viable from the aforementioned points of view because the introduction of diluent
Zr alloy, spectrum moderator BeO, and lower core height enables Doppler reactivity coefficient and burn-up reactivity swing of uranium-free TRU metallic fuel to be
as practicable as those of conventional fuel containing uranium.
Keywords Burn-up swing • Doppler reactivity feedback • Fast reactor • Metallic
fuel • Trans-uranium • Uranium-free
K. Ishii • M. Yamaoka • Y. Moriki • T. Oomori • Y. Tsuboi • K. Arie (*)
Toshiba Corporation, 8 Shinsugita-Cho, Isogo-Ku, Yokohama 235-8523, Japan
e-mail: kazuo.arie@toshiba.co.jp
M. Kawashima
Toshiba Nuclear Engineering Service Corporation, 8 Shinsugita-Cho, Isogo-Ku,
Yokohama 235-8523, Japan
© The Author(s) 2015
K. Nakajima (ed.), Nuclear Back-end and Transmutation Technology for Waste
Disposal, DOI 10.1007/978-4-431-55111-9_15
155