I recently posted a blog article about how the Russians were working on floating nuclear reactors on a barge. They are going to use them in ports, remote areas near a coast and in the Arctic to supply power to oil drilling rigs. I was skeptical about the wisdom of putting reactors out to sea but it turns out that not only the Russians are working on the idea. Nuclear engineers at MIT in the U.S. are going beyond the Russians in suggesting that a floating nuclear reactor be combined with an oil drilling rig.
The MIT research team points out that although nuclear plants are attractive because they reduce carbon emissions, the process of licensing and constructing a nuclear power reactor is long and often runs overtime and budget. Siting a plant is difficult because there must be a body of water nearby to cool the reactor and there is often local opposition to any particular location being considered. Since Fukushima, public support for nuclear power has declined and investors eager to fund new reactors are harder to find. Building floating nuclear power reactors and anchoring them offshore can solve these problems because siting ceases to be a contentious issue, there is plenty of sea water for cooling and the danger to people and the environment on land is reduced.
The MIT concept calls for an Offshore Floating Nuclear Plant that would be about forty five feet in diameter, mounted on an deep sea oil drilling platform. It would be able to generate about 300 megawatts. A one gigawatt OFNP would be about seventy five feet in diameter. Both models would include a helipad and living quarter for the crew. The reactor is in a pressure vessel low in the structure for stability. There is an empty chamber around the pressure vessel called the "containment" and then a hull around the containment separated by a gap. Beyond the hull is an area that is open to the seawater
The technology for oil rigs is well developed and a thriving industry to build them exists. There is also well developed technology and existing industry for seagoing nuclear reactors which power many naval vessels. The MIT design is thus combining two mature technologies with existing supply chains and construction expertise. The OFNPs would be constructed in existing shipyards so it would not be necessary to transport personnel, equipment and materials to a new site to construct each new reactor. The OFNPs are constructed mainly of steel so there is no need to pour huge amounts of concrete which emit significant quantities of carbon dioxide when nuclear power reactors and containment vessels are constructed on land.
Following construction, the OFNP will be towed out to sea about ten miles. This is far enough away from coastlines to pose no threat to civilian populations. The water will be at least one hundred meters deep which will protect the OFNP from tsunamis and earthquakes. If there is an accident, seawater can be used to cool the reactor hull without contaminating the seawater. This is a passive system with no pumps. The design even prevents "thermal" pollution that might threaten the ocean ecosystem. There is sufficient spent fuel storage space onboard to take all the spent fuel created during the operational lifetime of the OFNP. When a OFNP is decommissioned, it would be towed back to shipyards that already do such decommissioning work today.
While the MIT design is an interesting concept, there may still be problems with hurricanes. There will be danger to coastal areas when the OFNP is constructed but has not yet been towed out to sea or when it is towed in for service or decommission. And, the spent nuclear fuel will still have to be dealt with which is currently an unsolved problem. I think that offshore wind farms or floating solar power arrays would be a much better choice.
Artist's concept of MIT Offshore Floating Nuclear Plant:
