Underwater Nuclear Power Stations to be Built in the English Channel?

The Ecologist reports that France is starting a two year project looking into the feasibility of underwater nuclear reactors.

In an attempt to bring what France considers dependable energy to remote coastal communities, the French government has given the go ahead for a nuclear power programme where smaller nuclear reactors are to be based on the seabed.  The concept for the nuclear submarine, known as FlexBlue, involves a cylindrical vessel about 100 metres long and 15 metres in diameter that would encase a nuclear power plant with an electrical capacity of between 50 MW and 250 MW (between about 4% and 21% of Sizewell B’s output).

Flexblue would comprise a small nuclear reactor, a steam turbine-alternator set, an electrical plant and associated electrical equipment. Submarine power cables would carry electricity from the Flexblue plant to the coast.  With estimated costs at several hundred million Euros compared to about 5 billion Euros for a full-sized reactor, French engineers believe it could lead to a boom in the uptake of nuclear power.

Unerwater Nuclear Power

France is starting a two-year project looking into feasibility of underwater nuclear reactors

The plants would be designed to be moored, a few kilometres offshore, on a stable seabed at a depth of 60 to 100 metres with a system of ballast tanks to raise or lower the plants during installation and for major maintenance, refuelling or dismantling.

Flexblue nuclear plants would be stationary subsea installations with no independent means of propulsion. They would be transported by purpose-built vessels similar to those currently used to install offshore platforms. These same vessels would carry Flexblue plants to approved shipyards for refuelling, major maintenance and eventual dismantling.

The naval construction firm DCNS say submersion would provide a natural means of cooling the reactor – as well as enhancing security – and the only substance released into the environment would be the seawater used for cooling. The cores would be protected by three barriers: fuel cladding, reactor vessel and hull. The designers argue that immersion in sea water would ensure an infinite natural means of passive cooling; it is also argued that a submerged power plant would be less vulnerable to earthquakes, tsunamis, floods(!) and be far less vulnerable to terrorist attack.

Sceptics are concerned that warmer water released from the reactors could be dangerous for local ecosystem and, according to the President of the anti-nuclear organisation Crilan, should there be a nuclear accident “the sea will be destroyed.”

Of course, there are still no answers to the waste issues.  Given French engineers believe this project could lead to a boom in nuclear power, the issue of peak uranium should also be given serious consideration.  What about the environmental and human impacts of uranium mining?  And what about…, well, you can add your own reservations/concerns!

David M. Davison


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