Generation IV nuclear weapons could power future commercial ships

Lloyd's Register and nuclear startup Core Power are joining forces with shipping company Maersk to examine how to update regulations as part of efforts to deploy Gen IV nuclear reactors to power the next generation of zero-carbon cargo ships.

On July 21, 1959, a new era in commercial shipping began when the NS Savannah veered off the road and foundered at the New York Shipbuilding Corporation in Camden, New Jersey. The deliberately futuristic-looking passenger freighter was built at the then-astronomical cost of $46.9 million ($495 million in 2024) as part of the Eisenhower administration's Atoms for Peace program.

Savannah was never going to be economical to operate. She was a demonstration ship designed to demonstrate how nuclear power could be used for peaceful commercial operations. Although a remarkable piece of naval engineering and a fine example of atomic-age aesthetics with luxurious accommodations, she served only from 1962 to 1972 and was then scuttled and is now a museum ship in Baltimore, Maryland.

Only four nuclear cargo ships have ever been built, and only one, the Sevmorput, remains in service in Russia to serve Arctic trade routes. Despite initial optimism, the market for civilian nuclear-powered ships never materialized. Lifecycle costs proved too high to compete with conventional ships, the highly trained crews required to operate such ships were prohibitively expensive, and the port infrastructure for nuclear vessels was non-existent.

But the biggest blow has been dealt by complex and unclear local and international regulations and licensing requirements that make nuclear cargo ships a highly risky investment.

NS Savannah

Today, this is changing as the shipping industry is required to become carbon neutral by 2050. It is estimated that the shipping industry burns 300 million tons of fossil fuels per year in the form of heavy diesel, producing 3% of global greenhouse gas emissions. While other alternatives are being examined, some companies see nuclear energy in the form of Gen IV reactors as the most practical solution.

There are about 200 nuclear reactors operating on 160 naval ships and submarines worldwide, but despite having an excellent safety record, these military reactors are not suitable for civilian ships, mainly because of insurance issues. That's why companies and consortia such as America's TerraPower, Britain's Newcleo and Core Power, Norway's NuProShip, Italy's Fincantieri and Japan's Imabari Shipbuilding are looking at advanced reactors for large container ships and similar vessels.

These reactors are similar to advanced modular reactors and others developed for shore-based use. Specifically, the preferred models are the thorium-fueled molten salt reactor, in which thorium is dissolved in the salt coolant; the lead-cooled fast reactor, which replaces the water coolant with molten lead; and the helium gas-cooled pebble bed reactor, which uses three structurally isotropic (TRISO) nuclear fuel balls composed of layers of uranium, carbon, and ceramics.

What all these reactors have in common is that they do not need to be sealed in pressure vessels like most commercial reactors. They are much less complex, operate at lower temperatures, and are inherently safe because the nuclear reaction is self-regulating and, in the case of salt and lead reactors, the coolants solidify before any damage can occur in the event of an accident.

There are a number of technical hurdles to overcome, but the most vexing for the Lloyd’s-led group is regulation. So the partners are looking not only at how to make the best technical and commercial case for Gen IV nuclear cargo ships, but also how to reconcile or update existing regulations and make such vehicles a major player in the next 15 years.

“The launch of this joint venture marks the start of an exciting journey to unlock the potential of nuclear power in the maritime sector, paving the way for emissions-free operations, more agile service networks and greater efficiency across the supply chain,” said Nick Brown, CEO of Lloyd’s Register. “A multi-fuel pathway to decarbonise the maritime sector is crucial to ensuring we meet IMO’s emissions reduction targets as an industry, and nuclear propulsion is showing signs of playing a key role in this energy transition.”

Source: Lloyd's Register

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