Chapter 19
Transmutation Scenarios after Closing
Nuclear Power Plants
Kenji Nishihara, Kazufumi Tsujimoto, and Hiroyuki Oigawa
Abstract With consideration of the phase-out option from nuclear power
(NP) utilization in Japan, an accelerator-driven system (ADS) for Pu transmutation
has been designed and scenario analysis performed. The ADS is designed based on
the existing ADS design for MA transmutation, and the six-batch ADS was selected
as a reference design for scenario analysis. In the scenario analysis, the oncethrough scenario of light water reactor (LWR) spent fuel is referred to as a
conventional scenario with a LWR-MOX utilization scenario. As the transmutation
scenario, three cases of transmuters that are only-FR, only-ADS, and both-FR
+ADS are analyzed. The numbers of necessary transmuters are obtained as 15 to
32 units, and the necessary period for transmutation as 180–240 years. The benefit
on repository by reduction of Pu and MA is reduction of repository area by a factor
of five and of decay time of toxicity by one order of magnitude. The FR+ADS
scenario would be a modest solution, although the ADS scenario is preferable if
rapid transmutation is required.
Keywords ADS • Phase-out scenario • Scenario study • Transmutation
19.1 Introduction
After the Fukushima-Daiichi accident, Japan started a discussion of nuclear power
(NP) utilization including a “phase-out” option in addition to the usual scenario of
utilizing plutonium by deploying fast breeder reactors (FBRs). In the phase-out
option, construction of new plants is limited and dependency on NP will be
gradually reduced. One of the reasons supporting the phase-out scenario is an
ambiguous prospect of conducting underground disposal of radioactive wastes.
Increase of wastes can be limited or even stopped in the phase-out scenario, but
spent fuels (SFs) containing plutonium (Pu) and minor actinides (MAs) will remain
as a legacy of NP. “Direct disposal” to the underground of SFs confined in canisters
is considered as a strong option to treat this legacy, but Pu and MAs that exist in the
K. Nishihara (*) • K. Tsujimoto • H. Oigawa
Japan Atomic Energy Agency, 2-4 Shirane, Shirakata, Tokai-mura, Naka-gun,
Ibaraki 319-1195, Japan
e-mail: nishihara.kenji@jaea.go.jp
© The Author(s) 2015
K. Nakajima (ed.), Nuclear Back-end and Transmutation Technology for Waste
Disposal, DOI 10.1007/978-4-431-55111-9_19
207
Transmutation Scenarios after Closing
Nuclear Power Plants
Kenji Nishihara, Kazufumi Tsujimoto, and Hiroyuki Oigawa
Abstract With consideration of the phase-out option from nuclear power
(NP) utilization in Japan, an accelerator-driven system (ADS) for Pu transmutation
has been designed and scenario analysis performed. The ADS is designed based on
the existing ADS design for MA transmutation, and the six-batch ADS was selected
as a reference design for scenario analysis. In the scenario analysis, the oncethrough scenario of light water reactor (LWR) spent fuel is referred to as a
conventional scenario with a LWR-MOX utilization scenario. As the transmutation
scenario, three cases of transmuters that are only-FR, only-ADS, and both-FR
+ADS are analyzed. The numbers of necessary transmuters are obtained as 15 to
32 units, and the necessary period for transmutation as 180–240 years. The benefit
on repository by reduction of Pu and MA is reduction of repository area by a factor
of five and of decay time of toxicity by one order of magnitude. The FR+ADS
scenario would be a modest solution, although the ADS scenario is preferable if
rapid transmutation is required.
Keywords ADS • Phase-out scenario • Scenario study • Transmutation
19.1 Introduction
After the Fukushima-Daiichi accident, Japan started a discussion of nuclear power
(NP) utilization including a “phase-out” option in addition to the usual scenario of
utilizing plutonium by deploying fast breeder reactors (FBRs). In the phase-out
option, construction of new plants is limited and dependency on NP will be
gradually reduced. One of the reasons supporting the phase-out scenario is an
ambiguous prospect of conducting underground disposal of radioactive wastes.
Increase of wastes can be limited or even stopped in the phase-out scenario, but
spent fuels (SFs) containing plutonium (Pu) and minor actinides (MAs) will remain
as a legacy of NP. “Direct disposal” to the underground of SFs confined in canisters
is considered as a strong option to treat this legacy, but Pu and MAs that exist in the
K. Nishihara (*) • K. Tsujimoto • H. Oigawa
Japan Atomic Energy Agency, 2-4 Shirane, Shirakata, Tokai-mura, Naka-gun,
Ibaraki 319-1195, Japan
e-mail: nishihara.kenji@jaea.go.jp
© The Author(s) 2015
K. Nakajima (ed.), Nuclear Back-end and Transmutation Technology for Waste
Disposal, DOI 10.1007/978-4-431-55111-9_19
207