New Diplomacy Compass
Crossing Borders, Demystifying Japan
March 2023

From the Fast Breeder Reactor
to the Fast Reactor, and on to a White ElephantHajime Matsukubo
Citizens’ Nuclear Information Center (CNIC)

1. Introduction
Next-generation advanced reactors are currently a hot topic. This is due to Japanese Prime Minister Fumio
Kishida’s instruction to consider the promotion of nuclear reactor restarts, the removal of restrictions on reactor
operating periods, and the development and construction of next-generation advanced reactors at the second
meeting of the GX (Green Transformation) Implementation Council, a body under the auspices of PM Kishidahimself. However, what exactly was meant by next-generation advanced reactor was not made explicit at themeeting.
So, what is the next-generation advanced reactor? In April 2022, the Ministry of Economy, Trade and Industry(METI) set up an “Advanced Reactor Working Group” (hereafter, WG), which began discussions on issues suchas advanced reactor development and its social value. Of the 13 WG members, the author was the only one toparticipate from the nuclear-free camp. In July 2022, the WG completed an interim summary of arguments
entitled “A Technological Roadmap for Advanced Reactor Development toward the Realization of Carbon
Neutral and Energy Security (Draft Outline) ”.
Table 1. Outline of Next-Generation Advanced Reactors and METI Prospects for Introduction
Reactor Type

Reactor Features

Start of Construction

Start of Operation

Advanced LightWater Reactor

Large-scale light- water reactor with newtechnological features

Early 2030s

Mid-2030s

Small Light-WaterReactor

Nuclear reactor of power output capacity of up to300MW.

Mid-2030s

Early 2040s

Fast Reactor

A nuclear reactor utilizing fast neutrons.
Plutonium is bred in a blanket area surrounding
the reactor core when fuel is loaded into theblanket (blanket fuel). As more plutonium is bredthan used in nuclear fission, the reactor is called afast breeder reactor.

2040

Mid-2040s

2030

Mid-2030s

Mid-2030s

UndecidedHigh-Temperature
Gas Reactor

Nuclear Fission
Reactor

A nuclear reactor that uses helium gas as thecoolant. As ceramics and other materials are used
for the reactor core, the reactor can withstandhigher temperatures than the light-water reactor.
A nuclear reactor that utilizes nuclear fusion.

Source: Prepared by the author based on documents submitted to the Advanced Reactor Working Group, etc.

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New Diplomacy Compass
Crossing Borders, Demystifying Japan

According to this roadmap, next-generation advanced reactors refers to five kinds of reactors: advanced lightwater reactors (LWRs), small LWRs, fast reactors, high-temperature gas reactors, and fusion reactors. As anattachment to the Draft Outline, METI published a “Technological Roadmap toward Introduction” (Table 1) thatindicates a schedule for the development of the different reactor types. Looking at the roadmap, the earliestadvanced LWRs will be coming online in the mid-2030s. Further, for the fast reactor, thus far Japan’s mostfavored new reactor development, the thinking is that a demonstration reactor would start up in the mid-2040s.
(A demonstration reactor is a nuclear reactor constructed and operated to gain insights into technologicalreliability and economic performance, and the pathway to a commercial reactor generally passes through thestages of experimental reactor, prototype reactor, and demonstration reactor.) Up to now, the fast reactor
development plan targeted practical utilization by around 2050. This has been brought forward in the newroadmap, but the grounds for bringing the development forward are unclear.

2. A History of Problems and Obsession
From the start, Japan’s nuclear power development had aimed at developing a fast breeder reactor (FBR). For
instance, the first Atomic Energy Long-Term Plan by the Japan Atomic Energy Commission in 1956 alreadycontained the statement, “The future goal of nuclear reactor development is the domestic production of thebreeder power reactor.” The “breeder power reactor” means the FBR.

At the dawn of Japan’s introduction of nuclear power, all the advanced nuclear technology countries weresurging forward toward the development of the FBR. At the time, as uranium resources were scarce and thought
to eventually become exhausted, it was considered that the FBR would allay concerns over resource reserves.
Each of the countries, however, ran into development difficulties. Various challenges became apparent, but
especially problematic was that liquid sodium was used as the coolant. This is because sodium reacts violentlywith water. Russia’s FBR, the BN-600, for example, experienced 27 sodium leaks up to 1997, of which 14 leaks
resulted in fires. This was not a problem unique to Russia. France, the USA and other countries also ran intoproblems associated with sodium. The feared uranium resource depletion also did not occur.
There was also the problem that the FBR might lead to nuclear proliferation. In the FBR, the core is surrounded
by a “blanket” of uranium fuel, which breeds plutonium by absorbing fast neutrons. Plutonium exists in the formof both fissile and non-fissile nuclides, and the nuclide bred in the fuel blanket is highly fissile. With theexistence of these two issues, many countries put the development of the FBR on the back burner. Countries thatare even today striving to develop the FBR are France, Russia, China, USA, UK―the nuclear-weapon
states―and Japan. After spending approximately two trillion yen on developing the prototype FBR “Monju”, asodium leak accident in 1995 and other frequently occurring problems culminated in the termination of theproject in 2016. From the start of operation in 1994 to termination 22 years later, Monju ran for a mere 250 days.
Yet Japan has never abandoned FBR development, even though there is little prospect for Japan to build an FBR
inside the country anytime soon.
What Japan then jumped at was the French fast reactor ASTRID program. The purpose of ASTRID (AdvancedSodium Technological Reactor for Industrial Demonstration) was not to breed plutonium, but to convert longlived nuclear substances into short-lived ones using fast neutrons, which turned out to be very convenient forJapan. This was because, while uranium market prices fluctuate at an extremely low level, both France andJapan are facing severe problems with their excess civilian plutonium stocks. However, the ASTRID program,-2-New Diplomacy Compass
Crossing Borders, Demystifying Japan

which was to be a joint program involving the two countries, was cancelled by France in 2019. Franceannounced that it would not consider developing a high-cost fast reactor until at least 2050.
The next thing that Japan jumped at was the US VTR (Versatile Test Reactor) program. The US Department ofEnergy (DoE) set up this program in 2018 to conduct material tests for different types of fast reactors, andselected GE Hitachi Nuclear Energy (GEH) as the reactor vender. The construction cost has been set at amaximum of USD six billion, the total cost to be borne by the US government. Although the VTR is based onthe FBR PRISM (Power Reactor Innovative Small Module) designed by GEH, it does not have a power
generation capability. A memorandum of cooperation on the VTR was concluded between the governments ofJapan and the USA in 2019, but this program has also fallen into a very awkward situation.
Paradoxically, this was related to the development of the fast reactor Natrium that GEH had begun jointly withthe nuclear power venture company Terra Power (founded by Bill Gates). Currently, Terra Power has received
support from the US DoE and is aiming to complete the construction of Natrium, whose design is also based on
PRISM, by 2028. The VTR was initially planned to start operation in 2026, but delays in getting the construction
underway led to a planned construction start in 2027 with completion in 2032. The VTR was intended to conduct
the research necessary for Natrium, but the completion of VTR would be later than Natrium. If so, then the VTRis meaningless. At that point, the US Congress zeroed out funding for the VTR for 2022. The project Japan thenjumped at next was the fast reactor Natrium. In January 2022, the Japan Atomic Energy Agency, Mitsubishi
Heavy Industries, and Mitsubishi FBR Systems concluded a memorandum of cooperation with Terra Power.

3. What on Earth is the Fast Reactor for?
Japan originally chose the FBR path for the purpose of energy security. There are no commercial-scale uranium
resources in Japan, but the spent fuel from nuclear reactors contains plutonium. The idea is breeding to the“reduction of volume and toxicity level” of nuclear waste. In comparison with the direct geological disposal of
spent fuel, the volume and toxicity of the material (nuclear waste) remaining from reprocessed spent fuel isreduced. This is obvious. Plutonium and uranium are recycled as fuel, and the remaining radioactive materials,
such as iodine, noble gases, and tritium enclosed in the spent fuel, are released into the environment during
reprocessing. In addition, the zirconium cladding and other radioactive materials covering the nuclear fuel rods
are also separated out as nuclear waste. The resulting highly radioactive liquid waste is then solidified in glass toundergo geological disposal. In other words, “reduction of toxicity level” means either separating out toxic
materials before geological disposal or releasing them into the environment.
A further problem is how to handle the MOX fuel, fabricated from separated plutonium, after it has been used.
As spent MOX fuel generates considerably more heat and radiation than ordinary uranium fuel, it cannot behandled in the reprocessing plant now under construction at Rokkasho Village in Aomori Prefecture. Moreover,as the plutonium contained in spent MOX fuel consists largely of non-fissile plutonium, it is no longer efficient
to recycle it as fuel. Further, since the determining factor for the site area of the depository in geological disposal
is not the volume of the material to be disposed of but its degree of heat generation, in the end spent MOX fueldisposal results in almost no reduction in the size of the repository.
What can be done to realize the “reduction of volume and toxicity level” of nuclear waste? Firstly, the practicalutilization of the fast reactor, and secondly it would require the finer separation of radioactive materials, not at-3-New Diplomacy Compass
Crossing Borders, Demystifying Japanthe Rokkasho Reprocessing Plant, but at a new reprocessing plant.
However, is there any prospect of the fast reactor achieving practical utilization? For a reactor to reach thecommercial stage, a positive economic performance is necessary. Natrium is claimed to be a fast reactor with anexcellent economic performance, but with this being the maiden reactor, the necessary initial investment isforecast to be USD four billion (around 600 billion yen at an exchange rate of USD1 = JPY140). As the power
capacity is rated at 345 MW, that calculates out at JPY1.7 million/kW. In general, the construction cost for anuclear reactor in Japan being JPY400,000/kW, Natrium is roughly three times as expensive.

Figure1.Unit Cost of MOX Fuel and Uranium Fuel (UOX) (ton)
Source: Prepared by the author

For the fast reactor, it is not only the construction cost that is expensive; fuel costs are also significantly higher.
The reason is that producing the fast reactor fuel requires a reprocessing process. As for light water reactors,
when comparing MOX fuel with uranium fuel, domestically produced MOX fuel turns out to be 20 to 50 times
more expensive than uranium fuel per ton (Figure 1). Fast reactor MOX fuel contains more plutonium than thatfor light-water reactors, which results in a much higher cost.
It is said that the initial investment for nuclear power generation is high but fuel cost is inexpensive, and thus
nuclear reactors can provide relatively cheap electricity if reactors are kept running at a stable output level. But
the initial investment for fast reactors is far higher than for a conventional nuclear reactor, and fuel costs are also

several dozen times more expensive. Even supposing that the construction of new nuclear power plants shouldtake place, is there any power company that would select a fast reactor? The same goes for a new reprocessing
plant. It is estimated that the total cost of the currently under construction Rokkasho Reprocessing Plant isapproximately JPY14.4 trillion. Is it feasible that a second reprocessing plant be constructed?

4. Conclusion
The FBR was at one time thought of as Japan’s energy security trump card. However, the development ran into
trouble due to technological difficulties, the dream of plutonium breeding receded into the distance, and its
raison d’être shifted to a solution for the management of radioactive waste. Nevertheless, changing the signboard-4-New Diplomacy Compass
Crossing Borders, Demystifying Japan

does nothing to dispel the technological difficulties. There is also no advantage in terms of economicperformance. When nuclear power first arrived on the scene 60 years ago, it may have seemed that possible toutilize solar and wind power as extremely cheap power sources. Thinking of nuclear power as providing energy
security is plainly out of date. possible to utilize solar and wind power as extremely cheap power sources.
Thinking of nuclear power as providing energy security is plainly out of date.

Hajime Matsukubo
Secretary General of Citizens’ Nuclear Information Center (CNIC). Born in Hyogo Prefecture in 1979.
Graduated from International Christian University (ICU) in 2003 and completed the master’s program at theGraduate School of Public Policy and Social Governance at Hosei University in 2016. After working at afinancial institute, he joined the staff of CNIC from 2012. Has served, among others, as a member of the Nuclear
Power Subcommittee under the Advisory Committee for Natural Resources and Energy, Ministry of Economy,Trade and Industry (METI). His published works include “Kensho: Fukushima Daiichi Genpatsu Jiko
(Examination of the Fukushima Daiichi Nuclear Power Station Accident)” (Nanatsumori Shokan) and “Genpatsu

Saigai – Hinan Nenpyo (Nuclear Disaster – An Evacuation Timeline)” (Suiren Sha), and others.

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