adequacy of natural resources, waste reduction, nonproliferation, and public acceptance. Fast reactors with fuel recycle enhance the sustainability indices significantly, leading to the focus on sodium-cooled fast reactors (SFR) in the Generation
IV International Forum (GIF) and the International Project on Innovative Nuclear
Reactors and Fuel Cycles (INPRO) initiative of the International Atomic Energy
Agency (IAEA).
The necessary condition for successful fast reactor deployment is the understanding and assessment of innovative technological and design options, based on
both past knowledge and experience, as well as on ongoing research and technology
development efforts. The severe accident at Tokyo Electric Power Company’s
Fukushima Dai-Ichi Nuclear Power Station caused by the Great East Japan Earthquake and tsunami on March 11, 2011 prompted all countries to redefine their fast
reactor programs. To achieve the successful deployment of fast reactors, drastic
safety enhancement is the most important issue to be established, especially in
Japan, where the restart of nuclear power plants once these have been stopped is a
serious matter of argument.
The safety aspects of fast reactors (FRs) have been reviewed [1–4] in representative countries that have developed or have a plan to develop fast reactors in the
near future, especially after the Fukushima accident. These countries are improving
the safety of SFRs by considering the DiD (defense in depth). The designs of SFRs
should have tolerance to DBA (design basis accidents) and BDBA (beyond design
basis accident) caused by internal and external events. The inherent safety and
passive safety should be effectively utilized for reactor shutdown and reactor
cooling. For the case of severe accidents, it is indispensable first to shut down the
reactors. Furthermore, decay heat removal is also indispensable even in the case of
SBO (station black out). For SFRs, natural circulation can be expected in the
sodium heat transport systems and the decay heat can be removal to atmosphere
by the air cooling system.
In Japan, the Ministry of Education, Culture, Sports, Science and Technology
has launched a national project entitled “Technology development for the environmental burden reduction” in 2013. The present study is one of the studies adopted as
the national project. The objective of the study is the efficient and safe transmutation and volume reduction of MAs with long-lived radioactivity and high decay
heat contained in HLW in sodium-cooled fast reactors. We are aiming to develop
MA transmutation core concepts harmonizing MA transmutation performance with
core safety. The core concept is shown in Chap. 2. Also, we are aiming to improve
design accuracy related to MA transmutation performance. To validate and
improve design accuracy of the high safety and high MA transmutation performance of SFR cores, we developed methods for calculating transmutation rates of
individual MA nuclides and estimating the uncertainty of MA transmutation.
A new definition of transmutation rates of individual MA nuclides is derived in
Chap. 3. Using the definition, one can understand the physical meanings of transmutation for individual MA nuclides. Sensitivities are required to estimate the
uncertainty of MA transmutation rates from cross-section errors. In Chap. 4, sensitivity calculation methods are derived. First, the sensitivity calculation method
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T. Takeda et al.
IV International Forum (GIF) and the International Project on Innovative Nuclear
Reactors and Fuel Cycles (INPRO) initiative of the International Atomic Energy
Agency (IAEA).
The necessary condition for successful fast reactor deployment is the understanding and assessment of innovative technological and design options, based on
both past knowledge and experience, as well as on ongoing research and technology
development efforts. The severe accident at Tokyo Electric Power Company’s
Fukushima Dai-Ichi Nuclear Power Station caused by the Great East Japan Earthquake and tsunami on March 11, 2011 prompted all countries to redefine their fast
reactor programs. To achieve the successful deployment of fast reactors, drastic
safety enhancement is the most important issue to be established, especially in
Japan, where the restart of nuclear power plants once these have been stopped is a
serious matter of argument.
The safety aspects of fast reactors (FRs) have been reviewed [1–4] in representative countries that have developed or have a plan to develop fast reactors in the
near future, especially after the Fukushima accident. These countries are improving
the safety of SFRs by considering the DiD (defense in depth). The designs of SFRs
should have tolerance to DBA (design basis accidents) and BDBA (beyond design
basis accident) caused by internal and external events. The inherent safety and
passive safety should be effectively utilized for reactor shutdown and reactor
cooling. For the case of severe accidents, it is indispensable first to shut down the
reactors. Furthermore, decay heat removal is also indispensable even in the case of
SBO (station black out). For SFRs, natural circulation can be expected in the
sodium heat transport systems and the decay heat can be removal to atmosphere
by the air cooling system.
In Japan, the Ministry of Education, Culture, Sports, Science and Technology
has launched a national project entitled “Technology development for the environmental burden reduction” in 2013. The present study is one of the studies adopted as
the national project. The objective of the study is the efficient and safe transmutation and volume reduction of MAs with long-lived radioactivity and high decay
heat contained in HLW in sodium-cooled fast reactors. We are aiming to develop
MA transmutation core concepts harmonizing MA transmutation performance with
core safety. The core concept is shown in Chap. 2. Also, we are aiming to improve
design accuracy related to MA transmutation performance. To validate and
improve design accuracy of the high safety and high MA transmutation performance of SFR cores, we developed methods for calculating transmutation rates of
individual MA nuclides and estimating the uncertainty of MA transmutation.
A new definition of transmutation rates of individual MA nuclides is derived in
Chap. 3. Using the definition, one can understand the physical meanings of transmutation for individual MA nuclides. Sensitivities are required to estimate the
uncertainty of MA transmutation rates from cross-section errors. In Chap. 4, sensitivity calculation methods are derived. First, the sensitivity calculation method
180
T. Takeda et al.