London: Massachusetts Institute of Technology (MIT) scientists have designed the world's first floating nuclear plants — platforms modelled on those used for offshore oil drilling — that would be automatically cooled by surrounding seawater in case of a major tsunami like the one in Japan in 2011.
They say when tsunami struck the Fukushima Daiichi nuclear plant complex; neither the quake nor the inundation caused the ensuing contamination. Rather, it was the lack of cooling for the reactor cores, due to a shutdown of all power at the station, which caused most of the harm. In case of floating nuclear plants, during such a worst-case scenario, the surrounding sea water would indefinitely prevent any melting of fuel rods, or escape of radioactive material. Also, a floating platform several miles offshore, moored in about 100 metres of water, would be unaffected by the motions of a tsunami as earthquakes would have no direct impact at all. Jacopo Buongiorno, Michael Golay and Neil Todreas will present the concept of the design this week at an American Society of Mechanical Engineers symposium. Buongiorno sees a market for such plants in Asia, which has a combination of high tsunami risks and a rapidly growing need for new power sources. "It would make a lot of sense for Japan as well as places such as Indonesia, Chile and Africa," he said. Buongiorno said such plants could be built in a shipyard, and then towed to their destinations five to seven miles offshore, where they would be moored to the seafloor and connected to land by an underwater electric transmission line.
The concept takes advantage of two mature technologies: light-water nuclear reactors and offshore oil and gas drilling platforms. "Using established designs minimizes technological risks,'' said Buongiorno. The concept also makes it easier to do away with the plants at the end of its lifetime or decommissioning. This could be accomplished by simply towing it away to a central facility, as is done now for submarine reactors. That would rapidly restore the site to pristine conditions.
This design could also help to address practical construction issues that have tended to make new nuclear plants uneconomical. Shipyard construction allows for better standardization and the allsteel design eliminates the use of concrete which Buongiorno said is often responsible for construction delays and cost overruns. "There are no particular limits to the size of such plants,'' he said. "They could be anywhere from small, 50-megawatt plants to 1,000-megawatt plants matching today's largest facilities. It's a flexible concept."
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