Today, 200 nuclear reactors are operating on 160 vessels, mostly naval ships and submarines, but soon they could run on cargo ships, too:
Four nuclear-powered merchant ships have been built so far, all of them government-led projects begun mostly for developmental and testing reasons rather than purely commercial ones. The first was the American NS Savannah, built in the late 1950s at a cost of $46.9 million (an eye-popping $495 million today). It was in service from 1962 to 1972, but its pressurized light-water reactor (LWR) proved too complex and expensive for the ship to operate profitably. The Russian cargo vessel Sevmorput, commissioned in 1988, is the only nuclear-powered merchant ship still in operation as of early 2024. The other two ships, the Japanese Mutsu (1970) and the German Otto Hahn (1968), were both refitted with diesel engines partway through their service lives.
Nuclear power has been more successfully applied on submarines and ice-breaking vessels. The very first nuclear-powered vessel was the attack submarine USS Nautilus, in 1954, amid the 1950s heyday of nuclear-power research. Hundreds of nuclear reactors have since been used on ships and submarines. Russia currently operates seven nuclear-powered icebreakers.
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“Engines in ordinary ships are the size of houses,” says Emblemsvåg, who is leading NuProShip. And a great deal of space is taken up by fuel: “A container vessel going from Amsterdam to Shanghai requires roughly 4,000 tonnes of fuel.”
An SMR would be much more compact and lightweight. According to Emblemsvåg, a molten-salt reactor — which uses a mixture of thorium and hot liquid salts as both fuel and coolant — would also save about $70 million over the lifetime of a ship, compared with a similar vessel powered by engines that burn diesel fuel (or, more precisely, heavy fuel oil). Another plus for nuclear-propelled ships is easy access to an endless supply of cooling water.
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For ship propulsion, engineers have used pressurized-water reactors because they can produce higher power for a given mass compared with the other kind of light-water reactor, the boiling-water reactor. However, the technology comes with major challenges. They depend on complex control systems that need a technically trained operating crew, and they run on solid fuel rods that need to be replaced every 18 months. There’s also a risk, however slight, that the pressure vessel could explode.
Fourth-generation SMRs avoid all that. Emblemsvåg and the NuProShip team picked three reactor designs after analyzing 93 concepts in the International Atomic Energy Agency’s SMR handbook. One is a thorium-fueled molten-salt reactor. The second is a lead-cooled fast reactor, which replaces the water coolant of traditional reactors with molten lead. The third option, likely closest to market, is a helium gas-cooled reactor that uses a type of fuel called tristructural isotropic (TRISO), consisting of uranium particles encased in ultratough carbide and carbon layers that can handle temperatures above 2,000 °C.
“For ship propulsion, engineers have used pressurized-water reactors because they can produce higher power for a given mass compared with the other kind of light-water reactor, the boiling-water reactor. However, the technology comes with major challenges.”
Boiling water reactors are the most successful design for land-based power generation due to their ease of construction, ease of maintenance, long service life and the inherent safety of the design. I suspect that if you really did the math, BWRs are the most economical choice for civilian marine propulsion as well, even despite having a low power density. I would be very interesting to hear a nuclear engineer assess the feasibility of adapting a BWRX-300 small modular reactor to fit on a cargo ship.
Cargo ships use bunker fuel which is extremely cheap. It’s a residue of the refining process that is too viscous and has too much sulfur to be used in anything else. Refineries almost give it away. If cargo ships stop using it, what will refineries do with it? Burn it? Bury it underground?
The green idiocy keeps vomiting these stupid ideas. There is absolutely no reason to stick a nuclear reactor in a cargo vessel other than pander to some European nutjob hallucinating about zero emissions.
As long as the efforts to do this are not interfered with by governments, then have at it, and if there are accidents or incidents, then the parties affected by the accidents can hire lawyers (the ‘blegh’ option).
“…bunker fuel…is extremely cheap. It’s a residue of the refining process that is too viscous and has too much sulfur to be used in anything else. Refineries almost give it away. If cargo ships stop using it, what will refineries do with it? Burn it? Bury it underground?”
Bunker fuel contains useful sulfur that can (in theory) be extracted by responsible chemical companies that profit by delivering pure sulfur. Sulfur is nice when we use it in nice ways. Sulfur is not so nice when we disperse it as bunker fuel exhaust.
The devil as always is in the details. The chemical companies that could theoretically profit by responsible extraction of sulfur are not necessarily interested in chasing those profits. The companies that are willing to chase those profits don’t necessarily have the right tech know-how. Some companies will promise to have a green solution for extracting sulfur but will turn out to be scams like Solyndra. And so on.
Also, off-topic but I bet many readers here will love this:
https://spaceflightnow.com/2024/02/02/sierra-space-unveils-fully-integrated-dream-chaser-spaceplane-amid-testing-campaign/
While the volume of depleted nuclear fuel is very low, we have not been able to come up with a solution for its disposal, despite decades of trying. A large-scale expansion of such waste is quite problematic.
Many years ago a colleague of mine ran a research project for the US NRC regarding the decommissioning of old nuclear power reactors. He concluded that the cost of decommissioning equalled the cost of construction, but no power company had ever factored that cost into it operating budget. The US Navy simply sinks the reactors into the sea, which is very convenient to them, but leaves a problem for our posterity.
“The US Navy simply sinks the reactors into the sea, which is very convenient to them, but leaves a problem for our posterity.”
They do? I thought they put all that stuff in a trench at Hanford.
Since 1986, the service has disposed of 142 reactor compartment packages:
“There is absolutely no reason to stick a nuclear reactor in a cargo vessel other than pander to some European nutjob hallucinating about zero emissions.”
And then there are the ports that won’t let nuclear-powered vessels dock. That was one of the problems with the Savannah. And you have countries — New Zealand, for example — who have blanket bans on all nuclear-powered vessels in their waters.
The no-nuke propagandists have had some successes over the decades. The KGB got a decent return for its investment backing the nutball movements.
“While the volume of depleted nuclear fuel is very low, we have not been able to come up with a solution for its disposal, despite decades of trying.”
The fuel is mostly recycled. The problem is that the NRC treats “nuclear waste” like the children’s game “cooties”. Anything that was once radioactive is contaminated forever, even if the level of radioactivity was below normal background radiation.
Dixie Lee Ray, former head of the Atomic Energy Commission, had some blistering comments on such policies, but even being the nominal head wasn’t enough to overcome the bureaucracy.
“Bunker fuel contains useful sulfur that can (in theory) be extracted by responsible chemical companies that profit by delivering pure sulfur.”
Sulfur is the fifth most abundant element. Commercial mining consists basically of shoveling it off the ground and transporting it.
Purity varies, but sulfur is easily purified, plus there are already many industrial processes that produce sulfur as a waste product, steelmaking, for example.
Sulfuric acid: the next resource crisis that could stifle green tech and threaten food security
If I were the Pollution Czar, I would attempt to use governmental power to force oil companies to channel sulfur into non-polluting products. But of course I am not any kind of Czar, and I do not direct any kind of political authority or force.
I know sulfur is cheap, and oil companies don’t want to waste time selling cheap things. But pollution is a big externality cost for the planet and for ordinary people, so if the governments claim to protect the ordinary people, the governments ought to force the oil companies to pollute less.