UNDER cover of night, a fleet of nondescript freighters sets sail protected by a naval escort. The only cargo aboard each vessel is a mysterious cylindrical capsule some 3 metres across and 12 metres long. Ordinarily, there would be nothing unusual about shipping goods from the US around the world, but these 500-tonne containers are no ordinary freight. The ships are carrying a new generation of self-contained nuclear power plants destined for countries such as Libya, Namibia and Indonesia 鈥� nations that the US government would not normally trust with the custody of nuclear material.
So far this scenario is fiction, but the US-sponsored plan to make it happen, dubbed the Global Nuclear Energy Partnership (GNEP), is real enough. For the past two years, the US has been promoting GNEP as a way of meeting the developing world鈥檚 burgeoning appetite for energy. Nuclear power, the Bush administration claims, is the best option for cutting these countries鈥� dependence on fossil fuels 鈥� and thus their carbon emissions 鈥� while maintaining a secure baseload electricity supply.
Safety and security are the key selling points for this new generation of nuclear generators. The idea is to ship out complete nuclear power plants 鈥� including the reactor, cooling and heat-exchange systems 鈥� in a sealed, tamper-proof capsule that will run maintenance-free for 30 years, matching the lifetime of conventional reactors. Unpack it, plug it into a turbine and generator connected to the electricity grid and you鈥檙e away.
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An international race to be first to ship one of these 鈥渂lack box鈥� reactors has already begun. Russia and India both have advanced plans to supply the hundreds of small nuclear reactors to developing countries in the coming decades. However, advocates of GNEP say that these rival approaches are neither safe nor secure.
In April 2007, the Russian state nuclear energy company RosEnergoAtom began building the first of a batch of 35-megawatt nuclear reactors designed to be mounted on barges, towed to where they are needed, and hooked up to the local electricity grid. The units will first be deployed to provide power for the towns and cities rapidly developing along remote stretches of Russia鈥檚 Arctic coastline. Later, the company plans to sell them to other coastal nations too. Critics of this approach point to their vulnerability. In particular, standard safeguards against attacks by terrorists, such as partially burying a reactor underground and surrounding it with high-impact concrete walls, aren鈥檛 an option for these floating units.
The Nuclear Power Corporation of India, based in Mumbai, has built a number of Pressurised Heavy Water Reactors (PHWR), and hopes to export a 220-megawatt version of the reactor soon. The design has attracted criticism on security grounds. A country looking to get its hands on material for a nuclear weapon would find a unit like this highly desirable. As the reactor is a 鈥渉eavy-water鈥� type, it produces large amounts of plutonium as it burns uranium. In addition, it can be refuelled without being shut down, which might make it easier to conceal illicit activity from international monitoring agencies. 鈥淵ou could produce quite a bit of weapons-grade material in one year, enough for 10 bombs anyway, while you continue to operate; you鈥檙e just moving the fuel through,鈥� says Tom Shea of the US Department of Energy鈥檚 Pacific Northwest National Laboratory in Richland, Washington.
Safeguards for spent fuel
Projects like these helped spur the US to launch GNEP. Under this scheme, states that relinquish any ambition to build conventional nuclear stations will be given the opportunity to buy the new secure reactors instead. The UK, France, Canada, China and Japan are among the 20 nations 鈥� many of whom are developing similar reactors 鈥� that have signed up to the project. Participants agree to develop designs that safeguard against the possibility that reactor fuel could be diverted to make nuclear weapons, and to supply fresh fuel and collect spent fuel for reprocessing or storage in a way that ensures that none can go missing. They also undertake to share safety and security features in their designs. Participating nations that do not already have nuclear capacity 鈥� a growing list including Jordan, Kazakhstan and Senegal 鈥� agree not to develop uranium enrichment and reprocessing plants that could be used to develop material for nuclear weapons.
Over the coming months, the US Department of Energy will be inviting bids from the nuclear industry for a preliminary design that could be deployed within a decade. The winning bidder will be awarded $100 million, spread over five years, as they seek a licence for their design from the Nuclear Regulatory Commission (NRC). The competition is designed to jump-start the US nuclear industry, which has been at a near standstill since the accident at Three Mile Island power plant in Pennsylvania in 1979, when loss of coolant caused the reactor to overheat, melting part of the core and its fuel. Construction of the winning design could begin by 2015.
Other GNEP members are also hard at work. Argentina is planning to build prototypes for a 27-megawatt water-coooled reactor that could be ready for production within a decade, while South Korea has a 100-megawatt design running to a similar schedule. France has mature designs for a water-cooled reactor with an output in the range of 100 to 300 megawatts.
When it comes to safety, one of the key features is to build a reactor in such a way that the coolant will keep the core鈥檚 temperature under control in all conceivable circumstances. Failure could result in meltdown of the core and a massive release of radioactivity. Most existing reactors use water as a primary coolant, and are fitted with back-up systems to minimise the chances of catastrophe even if there is a failure such as a burst pipe, locked valve or loss of power. But even with multiple back-ups, a run of bad luck could mean that they all fail and an accident happens.
GNEP reactors follow a new approach. 鈥淭oday鈥檚 reactors are not your grandpa鈥檚 reactors,鈥� says Michael Driscoll, a professor of nuclear engineering at the Massachusetts Institute of Technology. Instead of relying on electrical or mechanical devices, the cooling systems will be 鈥減assive鈥�, driven entirely by phenomena such as convection or gravity. These features are being incorporated into the International Reactor Innovative and Secure (IRIS) project, a 335-megawatt reactor that is seen as a front runner in the US Department of Energy鈥檚 design competition. It is being built by an international consortium of public and private organisations, led by veteran nuclear reactor manufacturer Westinghouse. IRIS鈥檚 emergency cooling system exploits convection to cycle cooling water through the reactor, dramatically reducing the chances of a meltdown, Driscoll says.
The IRIS reactor is designed specifically for developing countries looking for a relatively small, inexpensive and easy-to-operate reactor that won鈥檛 overload their energy grid. 鈥淭he economics and design has to be something that fits for these countries that are coming up to nuclear for the first time,鈥� says IRIS鈥檚 lead engineer, Mario Carelli. He says each IRIS unit would cost about $1 billion, compared with roughly $7 billion for conventional gigawatt-scale reactors.
To keep the fuel for these reactors secure, one aim of the designs is to ensure they run as long as possible without refuelling. No one is likely to steal fuel from inside a working reactor, but new fuel rods in transit or stored on site are more vulnerable 鈥� and the same goes for spent fuel on its way to be reprocessed. At least one such theft has already occurred. In the late 1970s, two fresh fuel rods in Kinshasa, the capital of the Democratic Republic of the Congo. One of the rods was recovered in Italy in 1998; suggested the Italian Mafia was caught shipping it to an unnamed country in the Middle East. The other has never been found. 鈥淚f we start sending reactors en masse to countries that can鈥檛 even police them, the risk of another Kinshasa 鈥� or worse 鈥� happening could be all too high,鈥� says Edwin Lyman, a nuclear security specialist with the Union of Concerned 杏吧原创s in Washington DC.
IRIS is designed to operate for up to four years without refuelling, a big improvement on the 18 months conventional reactors require. Even better would be a reactor that can run for its entire 30-year design life without refuelling. Would that be possible?
A design that comes close is the Super Safe, Small and Simple, or 4S, a sealed reactor designed by Toshiba in Japan. Toshiba is seeking an NRC licence with a view to installing a 4S unit in Galena, a remote town on the Yukon river in Alaska that has so far had to rely on diesel generators for its electricity. The 4S would provide a steady 10 megawatts for 30 years, after which the entire reactor vessel would be shipped to a fuel reprocessing facility. The reactor鈥檚 modest output makes it ideal for remote sites like Galena, as well as installations such as mines and desalination plants. A 50-megawatt reactor has been designed for clients with a higher demand. But the 4S鈥檚 design does have one potential safety weakness: it uses liquid sodium metal as its coolant. Sodium reacts violently with water 鈥� even contact with moisture in the air could start a fire. 鈥淭here is no silver bullet, no perfect system,鈥� says Dan Ingersoll, a GNEP program director at the Oak Ridge National Laboratory in Tennessee. 鈥淭hat鈥檚 why there are 60-plus designs under development around the world. You solve one problem and introduce several more.鈥�
Researchers at Lawrence Livermore National Laboratory (LLNL) in California are pursuing a different type of reactor that runs for just as long without refuelling. Called the Small Secure Transportable Autonomous Reactor, or SSTAR, this is a 20-megawatt device contained in a vessel 3 metres in diameter and 12 metres long that ships fully assembled with a 30-year fuel supply sealed in. The unit is encased in a tamper-proof cask protected by an array of alarms that will warn of any attempts at interference via secure satellite radio channels.
The SSTAR unit leaves the factory with a layer of lead roughly 1 metre thick surrounding the reactor core. After the reactor starts up, the lead melts and from then on convection of the molten metal is enough to carry heat away from the core. Unlike sodium, lead isn鈥檛 flammable. 鈥淪uch a reactor system would operate with minimal intervention and little maintenance,鈥� says Craig Smith, a project leader on SSTAR for the LLNL. 鈥淚 don鈥檛 think you could flip the switch and walk away, but on the other hand you wouldn鈥檛 need a very large operational or security force to maintain it.鈥�
So how safe and secure will sealed reactors be? One thing that seems certain is that the host country will always be able to get hold of the fuel inside if it is determined enough. 鈥淭he countries could always kick out the inspectors, then you have to worry about compliance,鈥� says Hal Feiveson, a physicist and arms control expert at Princeton University 鈥淥ver 30 countries are actively considering embarking upon nuclear power programmes. We see the trouble we are having with Iran right now 鈥� you could imagine having five or six Irans out there.鈥�
There is also the possibility of a catastrophic accident. 鈥淭he notion of small, self-contained reactors where there is no advanced industrial infrastructure or expertise, no regulatory infrastructure for system monitoring, where emergency planning is sub-optimal or non-existent is really a recipe for disaster,鈥� says Lyman. Sabotage remains a possibility, too.
Ben Ayliffe, head of anti-nuclear campaigns at Greenpeace in the UK, thinks the whole plan is misguided. 鈥淚t鈥檚 one of those ideas you look at and ask: are these people for real?鈥� If providing electricity-generating technology to developing countries is our goal, then there are far more secure technologies 鈥� including solar, wind, hydropower, and increased energy efficiency 鈥� that don鈥檛 have the waste and military use issues that come with spreading uranium around the world, he says.
鈥淚t鈥檚 one of those ideas you look at and ask yourself: are these people for real?鈥�
Ingersoll, however, sees these reactors as a positive discouragement to the proliferation of nuclear technology compared with the alternative. 鈥淚f we say to the developing world, just wait 30 years and we鈥檒l give you the perfect solution to your energy needs, they are going to say no thank you and grab whatever power sources they can,鈥� he says. 鈥淩enewables are not even going to come close to meeting our current demands and won鈥檛 come anywhere near where we are expected to go.鈥�
He concedes that total security is probably unachievable. 鈥淲e will never have a completely proliferation-proof reactor, just like there will never be an 鈥榓ccident-proof鈥� car,鈥� he admits. But he still thinks it鈥檚 a goal worth striving towards. 鈥淲e should continue to improve the designs, at least to the point where the consequences are insignificant.鈥�
Judging by the pace at which less secure alternatives are being developed, and the urgent need for a quick source of clean energy, we may have little choice.
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