In Buddhist mythology, Monju is a Bodhisattva sitting serenely on a lion’s back, controlling raw nature with wisdom. In nuclear engineering, Monju is a prototype fast-breeder reactor which will be capable of generating 280 megawatts of electricity. It was an appropriate choice of name. Instead of controlling a lion, human wisdom – with the help of 1700 tonnes of liquid sodium – will control a plutonium fission reaction.
Fast-breeders represent nuclear energy at its most elegant . Within a tightly packed core, energetic neutrons from plutonium bombard a surrounding blanket of uranium, creating more plutonium. ‘Fast’ refers to the speed of neutrons in the core; ‘breeder’ to the fact that the end products contain more fissile material than went in. Twenty years ago, most rich countries were developing the technology: the US, Soviet Union, Britain, France and West Germany all built prototypes.
But when Monju goes critical early next year, it will be one of less than a dozen fast-breeder reactors in the world. Japan alone is continuing to increase investment in fast-breeders, which the government says will become commercially viable in the 2030s. Tokyo says this policy is part of a long-term energy strategy for which the world may one day be grateful. But critics, which include the government of the US as well as antinuclear groups, say that such a strategy may threaten worldwide progress towards nuclear disarmament and possibly lead to catastrophe.
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The reason is that Japan’s energy policy involves the movement and storage of large quantities of plutonium. The vital ingredient in fast-breeders’ fuel, plutonium is also the most convenient raw material for the manufacture of nuclear bombs. Japan’s move towards the plutonium economy begins in earnest towards the end of this year when a ship carrying 1 tonne of plutonium oxide extracted from Japanese fuel assemblies at the French reprocessing plant at Cap la Hague leaves Cherbourg for a seven-week voyage to Japan. Although this plutonium is not of the high purity used by advanced bomb-making plants, experts believe that it would be enough to construct 125 nuclear weapons, albeit relatively inefficient ones.
To guard against hijack by terrorists or rogue governments, the Shikishima, a specially built patrol ship, lightly armed with twin 35-millimetre cannon and 20-millimetre machine guns, will accompany the shipment. The voyage will be the first of the regular convoys that over the next 20 years will move around 30 tonnes of plutonium to Japan from Cap la Hague and Sellafield, its British equivalent.
Over the same period, Japan’s own small reprocessing plant, at Tokai north of Tokyo, will produce around 6 tonnes of plutonium. And, in 1999, the country’s first full-scale reprocessing plant, in Rokkasho at the very northern tip of Japan’s main island Honshu, will begin adding another 5 tonnes a year.
Critics both at home and abroad say the result will be a massive stockpile. Though Britain, for instance, now has a stockpile of around 40 tonnes of plutonium from its civilian nuclear programme, this has accumulated over more than 30 years. ‘Japan will become the world’s number one plutonium country,’ says Jinzaburo Takagi, a nuclear scientist who 25 years ago left one of Japan’s largest nuclear engineering companies to set up the Citizens’ Nuclear Information Centre, now the country’s most prominent antinuclear group.
The Japanese government claims it has no intention of accumulating plutonium. Apart from a small buffer stock, every kilogram delivered or manufactured will go directly into civil nuclear power stations. The Atomic Energy Commission, which sets Japanese nuclear policy, says it is a ‘national principle’ not to possess more plutonium than Japan needs for civil nuclear activities. Many critics accept the sincerity of such intentions. However, they point to a large and growing gap between Japan’s ability to accumulate plutonium and its ability to consume it.
INCREASING DEPENDENCE ON NUCLEAR POWER
The source of the predicament is Japan’s commitment in 1966 to a two-stage nuclear strategy. The first stage involved building American-designed nuclear power stations, fuelled on imported uranium, and sending spent fuel overseas for reprocessing. This is now reality. Japan has 39 commercial nuclear reactors, which generate more than a quarter of the country’s electricity. These are conventional thermal reactors, mainly boiling-water or pressurised-water reactors of the type being built at Sizewell in Suffolk. There are another 11 nuclear reactors under construction. The second stage of the strategy would break the dependence on foreigners: a Japanese reprocessing plant produces fuel for Japanese breeder reactors which in turn produce more plutonium.
Energy independence is important to Japan. Eighty per cent of its energy and almost all its coal, oil and gas are imported. The world’s resources of uranium are finite, and none lie within Japan’s borders. A conventional nuclear power station releases just 1 per cent of the energy in its fuel. Theoretically, a fast-breeder can extract 80 per cent.
Since the 1970s, fuel from Japan’s commercial nuclear power stations (the first of which was one of only two British Magnox reactors to be exported) has been sent to Sellafield and Cap la Hague for reprocessing into useful plutonium and uranium, which leaves high-level waste. The pace will pick up during the 1990s when new plants at Sellafield and Cap la Hague come on stream to handle fuel from light-water reactors.
The thermal oxide reprocessing plant, or THORP, to be run by British Nuclear Fuels, will handle 700 tonnes of fuel a year at full capacity; the UP3 and UP2-800 plants at Cap la Hague, to be run by Cogema, 800 tonnes each. Japanese electricity companies will be the largest customers. Each tonne of spent fuel contains about 9 kilograms of plutonium, which includes nonfissile isotopes as well as fissile plutonium-239. (These figures are approximate because reprocessing does not capture all the plutonium in fuel and authorities do not reveal the precise mix of isotopes in the finished plutonium, as the information would help a bomb maker.)
Japan has always intended to bring home both its plutonium and its waste. The original plan was to transport plutonium by air, in specially built containers carried on board Boeing 747s. To do so, however, would need permission from the US government, because the plutonium originated from American uranium, supplied with strict restrictions on its subsequent use. Washington signalled its disapproval by refusing to set technical standards for airborne containers. In 1988, Congress approved shipments of plutonium only if they travelled by sea, with an armed escort. This condition put Japan in a difficult position: for more than 40 years, it had never deployed armed forces overseas. To send the Maritime Self-Defence Force (as the Japanese navy is known) around the world would alarm neighbouring countries and outrage opinion at home. Instead, the government gave the job to the Maritime Safety Agency, a coastguard force. The agency had no ship capable of sailing halfway around the world, so the government spent 20 billion yen ( £87 million) on the 6500-tonne Shikishima, launched in June last year. The ship has a range of 37 000 kilometres and carries two helicopters.
Plutonium convoys are now ready to sail. The snag is that Japan has only one prototype plutonium-fuelled power station operating and one prototype being commissioned. Fugen and Monju, both named after Bodhisattvas, occupy neighbouring sites on the Tsuruga peninsula, about 400 kilometres west of Tokyo. By Japanese standards, the area is free of earthquakes, so it is also home to a complex of commercial reactors. Last February, one of these, Mihama number 2, achieved notoriety by causing the first accidental release of radioactivity in Japan’s nuclear programme.
Fugen, which has been operating since 1979, is an advanced thermal reactor. It is similar in design to the British Steam Generating Heavy Water Reactor at Winfrith in Dorset, which was closed down last year, and a distant cousin of Canadian Candu plants. Fugen differs from most commercial reactors because it uses heavy water to moderate the reaction. This allows it to run on a wide variety of fuels. One of its original purposes was to produce plutonium for fast-breeders. However, its operator, a public body called the Power Reactor and Nuclear Fuel Development Corporation (PNC), now says Fugen will ‘help utilise stockpiles of plutonium’. Today, it is running on a mixture of plutonium and uranium. The reactor is also a test-bed for techniques such as removing radioactive contamination with chemicals.
In theory, the next advanced thermal reactor will be a larger ‘demonstration’ ATR to be built at Ohma in Aomori prefecture, in the north of Honshu. The government wants private industry to pay for it. However, Japan’s nine electricity utilities are reluctant to invest in the technology. Engineers working on Fugen say the demonstration plant would cost half as much again as a conventional reactor. Another reason for reluctance is that the ATR, in which the fuel rods are encapsulated in a pressure tube, is the Japanese reactor closest in design to the RBMK reactor of Chernobyl notoriety. Although engineers cite a catalogue of differences between the two designs, borne out by Fugen’s remarkably high ‘average load factor’ (percentage of time delivering full power) of 64 per cent, it is quite another matter to persuade a local community of the difference. Fugen seems likely to be the last of its line.
Three kilometres along the Tsuruga peninsula, beneath a concrete dome painted green and beige to blend with the scenery, Monju is undergoing final tests and modifications before receiving its first fuel. It is actually Japan’s second prototype breeder; the first, Joyo, was smaller and did not include an electricity generator. The PNC is in charge of the project. Monju is an impressive piece of engineering: from the top of the reactor core, the interior of the dome towers 43 metres overhead. The reactor vessel, 18 metres high and 7 metres in diameter, is made from 12 pieces of stainless steel, assembled with only circumferential welds. The coolant, 1700 tonnes of liquid sodium, enters the reactor vessel at a temperature of 397 °C and emerges at 529 °C. Liquid sodium, also the coolant in British and French fast-breeders, was chosen for its ability to transfer heat quickly at atmospheric pressure without slowing down neutrons. However its use poses formidable engineering problems. ‘Sodium creates a serious safety risk unique to the liquid-metal fast-breeder reactor,’ says Thomas Cochran, head of nuclear policy at the National Resources Defense Council in the US.
The danger is of sodium reacting violently with water in a steam generator or even in concrete. If the sodium is radioactive, as it must be after passing through a reactor’s core, the result could be a cloud of radioactive steam. Much of the challenge of fast-breeder engineering goes into removing this danger. In Monju, a network of stainless steel pipes totalling 1.4 kilometres in length, each pipe as shiny as a drag-racer’s exhaust, keeps sodium and water apart.
Monju has two sets of sodium circuits. The primary system, which circulates entirely within the steel and concrete dome that shields the reactor, carries heat from inside the reactor’s core and itself becomes radioactive. A secondary sodium system, consisting of three loops of tubes each 360 metres long, transfers heat through the dome’s wall to a steam generator, which in turn drives a turbine to generate electricity. However, the tubing is prone to faults. During tests last year, which involved heating up the system nearly to its operating temperature, engineers noticed that the pipes were not expanding as expected.
The problem was with the flexible bellows that support the pipes of the secondary system where they pass through the containment wall. The bellows are designed to allow the pipes to expand outwards when heated, but when tested they proved too inflexible and 5 millimetres of expansion took place inside the dome. In fast-breeder engineering, 5 millimetres is a serious inaccuracy. (The gap between the base of the reactor vessel and its surrounding guard vessel is just 1 millimetre, for example.)
The fault set back the reactor’s date of going critical from October 1992 to early next year. It was only the latest in a long series of frustrations involving Monju, which has been under construction since 1983 – after a 10-year battle for permission. Even if Monju performs flawlessly, it will be a long way from a commercial fast-breeder. The next step will be to build a ‘demonstration’ reactor to bridge the gap between prototype and commercial plant. The government, which persuaded electrical utilities to cough up 20 per cent of Monju’s cost of 600 billion yen, wants private industry to pay for the demonstrator. But, as with the ATR, utilities have shown little enthusiasm for funding further work. Even the demonstrator will not be commercially viable. Tetsuo Kobori, deputy director of Monju construction, says that at least one or two further demonstrators will be needed to cut costs and simplify the design before the first commercial fast-breeder could enter service.
All this means that the fast-breeder will not be a significant contributor to the Japanese electrical grid for at least 30 years. Last August, Tokyo tacitly admitted that fact by announcing an important shift in energy policy. It would still bring its plutonium home, but for consumption in conventional pressurised-water and boiling-water reactors (known collectively as light-water reactors).
Reactor fuel normally contains a mixture of uranium-238, the predominant isotope in natural uranium, and a small quantity of uranium-235, a fissile isotope essential for maintaining a chain reaction. However, it is possible to substitute plutonium-239 for uranium-235. This fuel is known as MOX, for mixed oxides. Japan already has one small MOX plant, at Tokai, which is producing fuel rods for Monju. The government wants to turn this into a commercial business. ‘By around the year 2000 . . . the private sector will commercialise the fabrication of MOX fuel for the LWRs at an annual rate of about 100 tonnes,’ says the Atomic Energy Commission. The technology ‘contributes to the preservation of uranium resources and reduces the environmental effects caused by energy consumption’. The government intends to have two light-water reactors loaded with MOX fuel by the mid-1990s, four by 2000 and 12 by the end of the first decade of the 21st century. Critics, such as Takagi, say this is wildly unrealistic. One reason is cost: MOX is more expensive than enriched uranium. Also, the presence of plutonium makes handling of the fuel more difficult.
Electricity companies are also unenthusiastic, for political as well as technical reasons. The nationwide antinuclear movement, which flourished briefly after the Chernobyl disaster, is now dormant. No one wants to risk reviving the movement by announcing that they are generating electricity from the raw material of nuclear bombs. Switching to fuel containing plutonium involves technical and operational changes that might jeopardise Japan’s exemplary record of exposing workers in power stations to as little radiation as possible. Although no industry figure has publicly spoken out against national energy policy, the power companies are dragging their feet.
‘The utilities are very conservative,’ was one reply to a question about the private sector’s lack of enthusiasm for plutonium. The receding prospect of generating electricity from plutonium has led to several studies pointing to the gap between Japan’s ability to collect plutonium and its ability to consume it. One informed analysis is by Tatsujiro Suzuki, a Japanese nuclear engineer at the Massachusetts Institute of Technology’s Center for Energy Policy. He estimates that, by 2010, Japan will have accumulated between 80 and 90 tonnes of fissile plutonium: 30 tonnes from Europe, 6 tonnes from Tokai and 50 tonnes from Rokkasho. Breeder reactors and advanced thermal reactors will consume at most 40 tonnes.
Suzuki’s figures have particular credibility because he supports nuclear power (he sees fast-breeders integrated with reprocessing plants as the most promising technology), yet they are in line with those who oppose all nuclear activities. The Citizens’ Nuclear Information Centre estimates that Japan’s present nuclear programme will need, at most, 23 tonnes of plutonium for Fugen and Monju between now and 2010, or less than a quarter of the Atomic Energy Commission’s estimate. The centre says that by 2010 shipments from Britain and France, coupled with production at Tokai and Rokkasho, will produce a surplus of 77 tonnes, which will then continue to increase.
Last year, Takagi, the centre’s director, told an international conference organised by the centre and Greenpeace: ‘If the reprocessing policy is maintained, Japan will have an enormous stockpile of plutonium which will surpass in the 2020s all the military plutonium ever produced by nuclear superpowers for weapons use.’
Such a stockpile could have profound international consequences. Paul Leventhal, president of the Nuclear Control Institute, a private body in Washington DC, told the same conference: ‘It is paradoxical that, just as the US and the (former) Soviet states are winding down their arms race, Japan is preparing to acquire more plutonium than the two superpowers now have in all of their nuclear weapons combined . . . A large Japanese plutonium stockpile might make it politically and strategically impossible for the US and (the states of the former Soviet Union) to destroy the large stocks of plutonium that will be recovered from retired warheads.’ Leventhal also warned about the impact in east Asian countries, where memories of Japanese militarism linger on. ‘These nations cannot be expected to forgo plutonium if Japan proceeds with it.’
Even if Japan manages to avoid building up a stockpile, its use of large quantities of plutonium will still cause international concern. One worry is the risk of accidents in transport or storage. Greenpeace has evidence that ships transporting spent fuel from Japan to Europe have suffered several mishaps, though all were unrelated to the cargo. One ship made an unscheduled stop at Hawaii to receive medical help. One had to stop in the Caribbean following an engine room fire. Another, forced to sail around Cape Horn when American forces invaded Panama, suffered damage to both engines.
Critics also believe that, whatever precautions are taken against accident and hijack, it is impossible in practice to control the movement of plutonium accurately. Tokyo is sensitive to criticism. This year it will mount a diplomatic effort to persuade the world that it will not needlessly amass stocks of plutonium. One way to reduce anxiety would be to ship the European plutonium as MOX, which would be much less tempting to terrorists. Although Europe does not have the capacity to produce such quantities of MOX fuel at the moment, it aims to quadruple its capacity by 2005. However, Japan’s strategic aim is still to build its own commercial MOX plants.
So why does Japan persist in an expensive programme that at best is a propaganda gift to opponents of nuclear energy and, at worst, threatens disaster?
The first answer is that, to the Japanese establishment, energy security is an urgent and overriding concern. Kobori speaks eloquently and seriously of his fears: ‘In my opinion, by the year 2010 or 2015, we will have big competition, maybe war, over energy. In order to keep peace on earth, we need to develop new energy resources.’ The fast-breeder may be the only technology on the horizon capable of assuring a concentrated supply of energy for hundreds of years.
Opponents challenge this assertion. Cochran of the Natural Resources Defense Council says that, at present prices, the money spent on Monju could buy enough uranium to fuel Japan’s light-water reactors for 50 years. ‘If energy independence or wise economic investment were the objective, countries like Japan would abandon their breeder programmes and invest in stockpiled uranium.’
There are two other possible explanations for Japan’s persistence with plutonium. The conspiracy theory is that in the long term Tokyo aims to develop the capacity to build nuclear bombs at short notice should the international situation so demand. Today, the idea sounds absurd. In a country where virtually every schoolchild visits the museums at Hiroshima and Nagasaki, the idea of building a nuclear deterrent is completely off the political agenda. But there can be no guarantee that it will always be so.
The other, more likely, explanation is sheer inertia. Unlike Britain, the United States and Germany, whose energy policies are vulnerable to sudden shifts in the political climate, Japan tends to stick to long-term strategies. Consistency has had notable successes, most spectacularly in guiding industrial policy. But such a system can spawn bureaucratic inertia, making it impossible to cancel projects. The most celebrated example is the Mutsu, a nuclear-powered ship that consumed 50 billion yen over 20 years when all technical and economic logic called for the project to be abandoned.
It is too early to tell if Monju and the rest of Japan’s plutonium infrastructure will suffer a similar fate. But it is certain that, whether by foresight, conspiracy or cockup, Japan is becoming a nuclear superpower.
Michael Cross is a freelance journalist.
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THE REACTOR THAT MAKES MORE FUEL THAN IT USES
Fuel for commercial nuclear power stations contains two isotopes of uranium, to the power of 235U and to the power of 238U. Pressurised-water and boiling-water reactors, which dominate the nuclear business, run on fuel enriched to increase the proportion of to the power of 235U, the fissile component. to the power of 238U, which is nonfissile, makes up 99 per cent of natural uranium.
238U capture neutrons, to create plutonium-239 ( 239Pu). The plutonium in spent fuel contains at least 50 times as much energy as the reaction released.
239Pu, which makes up about 60 per cent of the plutonium produced by civil reprocessing plants, is a convenient raw material for the manufacture of nuclear weapons.
There are two ways to exploit the fissile energy of 239Pu The reaction consumes more plutonium than it creates.
The second way is in a fast-breeder reactor. Conventional reactors need a moderator to slow down neutrons produced by fission, because neutrons travelling too quickly usually pass through other nuclei rather than splitting them and maintaining the chain reaction. In PWRs and BWRs, water doubles as moderator and coolant. Fast reactors have no moderator and rely on unimpeded ‘fast’ neutrons to keep the reaction going.
Although most fast neutrons miss their targets or pass clean through them, when they do hit, each spawns several new neutrons. A nucleus of 239 238U into 239Pu. Such a ‘fast’ reactor ‘breeds’ more plutonium than went into it in the first place, hence the name.
A reprocessing plant can extract this plutonium, mix it with more depleted uranium and so achieve an almost endless source of energy. But while uranium is in abundant supply and fast-breeder reactors confined to a handful of prototypes, no one has begun to exploit this energy cycle commercially