Chapter 16
Enhancement of Transmutation of Minor
Actinides by Hydride Target
Kenji Konashi and Tsugio Yokoyama
Abstract A hydride target including minor actinides (MA) is able to enhance the
transmutation rate in a fast breeding reactor (FBR) without degradation of core
safety characters. Fast neutrons generated in the core region of the FBR are
moderated in the MA-hydride target assemblies and then efficiently absorbed by
MA. The MA-hydride target pin has been designed in the light of recent research of
hydride materials. This chapter shows the feasibility of MA transmutation by an
existing reactor, Monju.
Keywords Fast breeder reactor • Hydride • Minor actinide
16.1 Introduction
High-level wastes generated after reprocessing spent nuclear fuels include longlived radioactive nuclides of minor actinides (MA), such as
237 Np,
241 Am,
243 Am,
and
244 Cm. A currently available method for the final disposal of the high-level
wastes is to vitrify them under rigid control, to store them in monitored locations
until the radiation decays to allowable levels, and then to dispose them
underground.
The transmutation of MA by the fast breeder reactor (FBR) has been intensively
studied to reduce radioactivity of the wastes [1]. Transmutation rate, which is one of
the most important factors for transmutation methods, is determined by values of
neutron flux and nuclear reaction cross section as follows:
λ ¼
Z
Φ n E
ð Þσ n E
ð ÞdE
K. Konashi (*)
Institute for Materials Research, Tohoku University, Oarai, Ibaraki-ken 311-1313, Japan
e-mail: konashi@imr.tohoku.ac.jp
T. Yokoyama
Toshiba Nuclear Engineering Services Corporation, 8 Shinsugita, 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_16
169
Enhancement of Transmutation of Minor
Actinides by Hydride Target
Kenji Konashi and Tsugio Yokoyama
Abstract A hydride target including minor actinides (MA) is able to enhance the
transmutation rate in a fast breeding reactor (FBR) without degradation of core
safety characters. Fast neutrons generated in the core region of the FBR are
moderated in the MA-hydride target assemblies and then efficiently absorbed by
MA. The MA-hydride target pin has been designed in the light of recent research of
hydride materials. This chapter shows the feasibility of MA transmutation by an
existing reactor, Monju.
Keywords Fast breeder reactor • Hydride • Minor actinide
16.1 Introduction
High-level wastes generated after reprocessing spent nuclear fuels include longlived radioactive nuclides of minor actinides (MA), such as
237 Np,
241 Am,
243 Am,
and
244 Cm. A currently available method for the final disposal of the high-level
wastes is to vitrify them under rigid control, to store them in monitored locations
until the radiation decays to allowable levels, and then to dispose them
underground.
The transmutation of MA by the fast breeder reactor (FBR) has been intensively
studied to reduce radioactivity of the wastes [1]. Transmutation rate, which is one of
the most important factors for transmutation methods, is determined by values of
neutron flux and nuclear reaction cross section as follows:
λ ¼
Z
Φ n E
ð Þσ n E
ð ÞdE
K. Konashi (*)
Institute for Materials Research, Tohoku University, Oarai, Ibaraki-ken 311-1313, Japan
e-mail: konashi@imr.tohoku.ac.jp
T. Yokoyama
Toshiba Nuclear Engineering Services Corporation, 8 Shinsugita, 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_16
169