The future of nuclear-powered ships

Naval vessels such as submarines and aircraft carriers have been using nuclear reactors for decades, so the concept is not new, but there is renewed interest in applying this technology to commercial shipping, especially as the industry strives for carbon neutrality. Nuclear provides a high-density, reliable energy source, but substantial challenges stand in the way.

A nuclear-powered ship uses a nuclear reactor to generate heat, which is then converted into electricity or mechanical energy to drive the ship’s propulsion system. The most common type is the pressurised water reactor (PWR), but advanced reactor designs such as molten salt reactors and pebble-bed reactors are emerging. These modern designs are considered inherently safer because they operate at lower pressures and use materials that solidify in case of malfunction, reducing the risk of a catastrophic meltdown.

These engines work by sustaining a controlled nuclear fission reaction in the reactor core. The energy produced heats a coolant, which then transfers heat to a secondary system to produce steam. The steam drives a turbine, generating electricity or mechanical power to move the vessel. This system allows ships to operate for extended periods without refuelling, as nuclear fuel can last for several years before it needs to be replaced.

Only four nuclear-powered commercial vessels have ever been built. The first was the NS Savannah, launched in 1959, followed by ships in Germany, Japan and Russia. Due to high operational costs, regulatory challenges and public concerns, nuclear-powered cargo and container ships have not yet gained widespread acceptance.

However, advancements in reactor technology have reignited interest in nuclear-powered shipping. Companies like TerraPower and Newcleo are developing next-generation reactors that could power cargo and container ships, potentially offering a zero-emission alternative for long-haul trade.

Nuclear-powered ships offer a number of advantages.

Nuclear-powered ships produce no direct greenhouse gas emissions, which makes them an attractive option for meeting the International Maritime Organization’s (IMO) carbon neutrality goals.

A nuclear-powered cargo ship can operate for years without needing to refuel, providing significant advantages for long-distance routes. This is particularly useful in remote regions like the Arctic, where bunkering stations are sparse.

Nuclear reactors are highly energy-dense, meaning they require much less fuel to generate the same amount of power compared to fossil fuels. This results in lower operational costs over time, despite the high cost of the initial investment.

As global fuel prices fluctuate and shipping companies face fuel shortages or sanctions, nuclear propulsion could offer independence from traditional fuel sources, providing more predictable operational costs.

There are also a number of challenges that must be surmounted.

The construction and maintenance of nuclear-powered ships require a significant upfront investment. In addition to building the reactors, operators must install specialised port infrastructure to handle nuclear refuelling and waste management.

Due to safety and environmental concerns, nuclear-powered ships are subject to a long list of international regulations. Existing frameworks are being updated to accommodate new reactor designs, but regulatory uncertainty remains a barrier to widespread adoption.

The idea of nuclear-powered ships still carries a significant stigma due to historical accidents and the fear of radiation leaks. Educating the public and proving the safety of these reactors is essential to gaining broader acceptance.

Managing spent nuclear fuel is another challenge. While reactors designed for shipping may produce less waste than traditional reactors, handling and disposing of radioactive material in a maritime context presents logistical and environmental risks.

As shipping companies look for ways to meet ambitious carbon reduction targets, nuclear-powered container ships may emerge as a viable option. The development of advanced reactor technology offers the potential for safer, more efficient nuclear propulsion. However, overcoming regulatory, cost and public perception barriers will be crucial before nuclear power can become a mainstream solution in the commercial shipping sector.