Pierre Aury discusses all things nuclear shipping.
The first wind-powered boats were sailing more than 5,000 years ago. Wind propulsion reached a golden age of sail in the mid-19th century, and the last commercial ocean-going sailing ship was the Pamir, which sank off the Azores in 1957. Built in 1905, she was 114 m long and 14 m wide, with a deadweight of 4,500 tons. She was powered by 3,800 sq m of sails and could reach a top speed of 16 knots.
But shipping was carbon-free when the world was … carbon-free as well (except for the wood used for heating, melting ores, and cooking food). Regardless of likely improvements to be made in the near future and some specific uses, wind power will never be a viable solution for the world merchant fleet. At best, wind power may generate some fuel savings — and even that is open to debate.
Carbon-free or carbon-neutral alternative fuels will not exist in sufficient quantities, nor be available quickly enough, to drive the energy transition at sea — not to mention the fact that some of these alternative fuels are highly toxic. These facts, combined with the self-inflicted target of becoming the first decarbonised industry in the world, leave shipping with only one alternative: nuclear propulsion.
Here we are talking about nuclear fission, not fusion. As these lines are being written, there are 160 ships powered by 200 nuclear reactors sailing around the world. Most of them are navy ships — aircraft carriers and submarines. They are all powered by reactors using a technology called PWR (pressurised water reactor), the same technology used in nuclear power plants. For a number of reasons, this technology is not suitable for merchant vessels.
SMR stands for small modular reactor. An SMR typically ranges from 10 to 300 megawatts, whereas a typical shore-based nuclear reactor ranges from 1,000 to 1,600 megawatts. There are close to 80 different technologies available for SMRs.
To date, only Russia and China operate SMRs: Russia uses one on a barge in the east to produce electricity, and China operates a land-based one in Gansu province. Both are using thorium molten salts as fuel and coolant.
The issues to be dealt with before we see SMRs on ships are numerous.
Regulation is the first challenge: the IMO and member states must produce a legal framework for nuclear propulsion — a process that will surely take years.
Economics pose another major hurdle. It is difficult to estimate the cost of installing an SMR on a ship. Moreover, SMRs can function for the entire life of the ship without refuelling. In some cases, the net present value (NPV) of the fuel cost exceeds the value of the vessel itself. Will banks treat the nuclear fuel as a capital expense and finance it accordingly?
Finally, the critical issue of radioactive waste produced by SMRs appears to be largely ignored — or at least significantly downplayed. The same goes for the issue of decommissioning SMRs when vessels are scrapped.
In short, SMRs offer — on paper at least — a credible zero-carbon option for shipping. But it’s hard to imagine the first purpose-built or retrofitted merchant vessel equipped with a small modular reactor before 2030.
Too little, too late?
