After the events of March 11, 2011, when an earthquake and tsunami led to a meltdown of three nuclear reactors at the Fukushima Dai-ichi power plant in Japan, you might be forgiven for concluding that atomic power and seawater don’t mix.
Many engineers, though, do not agree. They would like to see more seawater involved, not less. In fact, they have plans to site nuclear-power plants in the ocean rather than on land—either floating on the surface or moored beneath it.
At first this sounds crazy. It is not. Land-based power stations are custom-designed structures, built by the techniques of civil engineering, in which each is slightly different and teams of specialists come and go according to the phase of the project. Marine stations, by contrast, could be mass-produced in factories using, if not the techniques of the assembly line, then at least those of the shipyard, with crews constantly employed.
That would make power stations at sea cheaper than those on land. Jacopo Buongiorno, a nuclear engineer at the Massachusetts Institute of Technology, reckons that, when all is said and done, electricity from a marine station would cost at least a third less than energy from a terrestrial equivalent.
It also would make them safer. A reactor anchored on the seabed would never lack emergency cooling, the problem that caused the Fukushima meltdown. Nor would it need to be protected against the risk of terrorists flying an aircraft into it. It also would be tsunami-proof: Though tsunamis become great and destructive waves when they arrive in shallow water, in the open ocean they are mere ripples. Indeed, were it deep enough—330 or so—such a submarine reactor would not even be affected by passing storms.
According to Jacques Chénais, an engineer at France’s atomic-energy commission, CEA, all these reasons make underwater nuclear-power stations an idea worth investigating. Chénais is head of small reactors at CEA, and has had experience with one well-established type of underwater reactor, the kind that powers submarines. He and his team are now assisting Naval Group, a French military contractor, in designing reactors that will stay put instead of moving around on a boat. The plan is to encase a reactor and an electricity-generating steam turbine in a steel cylinder the length of a football field and with a weight of around 12,000 tons.
The whole system, dubbed Flexblue, would be anchored to the seabed between three and nine miles from the coast—far enough for safety, in case of an emergency, but near enough to be serviced easily. The electricity generated, as much as 250 megawatts, enough for 1 million people, would be transmitted ashore by an undersea cable. For refueling and maintenance unmanageable from a submarine, the cylinder would be floated to the surface with air injected into its ballast tanks. When a station came to the end of its useful life, it could be towed to a specialist facility to be dismantled safely, rather than requiring yet another lot of civil engineers to demolish it.
Naval Group has not, as yet, attracted any customers for its designs. However, a slightly less ambitious approach to marine reactors—anchoring them on the surface, rather than below it—is about to come to fruition in Russia.
The first such, Akademik Lomonosov, is under construction at the Baltic Shipyard in St. Petersburg. According to Andrey Bukhovtsev of Rosatom, the agency that runs Russia’s civil nuclear program, it is 96% complete. It will be launched later this year, towed to Murmansk and thence transported to Pevek, a port in Russia’s Far East, where it will begin generating power in 2019.
Akademik Lomonosov consists of two 35-megawatt reactors mounted on a barge. The reactors are modified versions of those used to power Taymyr-class icebreakers. As such, they are designed to be able to take quite a battering, so the storms of the Arctic Ocean should not trouble them. To add to their safety, the barge bearing them will be moored, about 650 feet from shore, behind a storm-and-tsunami-resistant breakwater.
Altogether Akademik Lomonosov will cost $480 million to build and install—far less than would have to be spent constructing an equivalent power station on land in such a remote and hostile environment. On the presumption that the whole thing will work, plans for a second, similar plant are underway.
Nor is Russia alone in planning floating reactors. China has similar ambitions, though the destinations of the devices concerned are more controversial than those in Russia. Specifically, the Chinese government intends, during the 2020s, to build as many as 20 floating nuclear plants, with reactors as powerful as 200 megawatts, to supply the artificial islands it is building as part of its plan to enforce the country’s claim to much of the South China Sea—a claim disputed by every other country in the area.
Not everyone is delighted with the idea of marine nuclear power. Rashid Alimov, head of energy projects at Greenpeace Russia, an environmental charity, argued that offshore plants could be boarded by pirates or terrorists, could be struck by an iceberg or might evade safety rules that are hard to enforce at sea. On July 21 Greenpeace scored a victory when Rosatom said that Akademik Lomonosov’s nuclear fuel would be loaded in an unpopulated area away from St. Petersburg.
© 2017 Economist Newspaper Ltd., London (August 12). All rights reserved. Reprinted with permission.
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