Ulstein debuts Thor, claiming it is shipping’s nuclear-powered silver bullet

One of Europe’s top ship designers has come out with its own designs for nuclear-powered ships.

Norway’s Ulstein, which also builds vessels, has debuted the Ulstein Thor, a 149 m long concept ship featuring a thorium molten salt reactor (MSR) which would operate as a mobile power/charging station.

While initially aimed at the cruise sector, a spokesperson for the company told Splash today that Ulstein was confident nuclear power could work for most merchant ship types too.

“We believe the MSR technology can be applied directly in most vessel types. We have huge confidence in this solution and want to engage further in conversations about how we can enable the necessary changes the world demands,” the spokesperson said.

This is the most viable, and potentially the only credible, solution for a zero emission fleet that can operate under commercial terms and cost levels

In a release Ulstein said it believes its Thor concept may be the missing piece of the zero emissions puzzle for a broad range of maritime and ocean industry applications. To demonstrate its feasibility, Ulstein has also developed the Ulstein SIF concept, a 100 m long zero emission expedition cruiseship. This ice class 1C vessel would run on next generation batteries, utilising Thor to recharge while at sea.

“We have the goals, ambition and environmental imperative to switch to zero emission operations, but, until now, we haven’t had the solution,” commented CEO Cathrine Kristiseter Marti. “We believe Thor might be the answer we’ve been looking for. Thor is essentially a floating, multi-purpose power station that will enable a new battery revolution.”

Thorium, an abundant, naturally occurring metal with low radioactivity, has been identified as having potential for a maritime industry hunting for clean alternative fuels.

Speaking about the suitability of thorium MSRs as an energy source for maritime applications, Jan Emblemsvåg, professor at Norwegian University of Science and Technology, commented: “MSRs have enormous potential for enabling clean shipping. There is so much uncertainty over future fuels, but here we have an abundant energy source that, with the right approach, can be safe, much more efficient, cheaper, with a smaller environmental footprint than any existing alternative. From my perspective I see this as the most viable, and potentially the only credible, solution for a zero emission fleet that can operate under commercial terms and cost levels. The Thor concept is exactly the kind of innovation we need for sustainable success at sea.”

Proponents of nuclear propulsion are growing in number and voice. Core Power, arguably the highest profile marine atomic developer in the market, can now boast 49 shipping companies as backers of the UK firm, a grouping made up of owners, operators and managers who, combined, control more than 4,000 ships. Core Power units are based on marine MSRs, a technology using high-assay low-enriched uranium (HALEU).

Other notable marine atomic developments are taking place in South Korea where shipbuilding major Samsung Heavy Industries has teamed up with the Korea Atomic Energy Research Institute while Seaborg Technologies in Denmark is building floating power barges, and the Canadians are working with NuScale to develop marine power stations. The Russians, meanwhile, already have the market domestically and are now touting a huge new next generation nuclear-powered icebreaker as further proof of their maritime atomic expertise.

Not to be left out, Chinese scientists are developing their own atomic propulsion technologies for both merchant marine and offshore facilities. China has also been testing a thorium-powered nuclear reactor, the world’s first since 1969.

Sam Chambers

Starting out with the Informa Group in 2000 in Hong Kong, Sam Chambers became editor of Maritime Asia magazine as well as East Asia Editor for the world’s oldest newspaper, Lloyd’s List. In 2005 he pursued a freelance career and wrote for a variety of titles including taking on the role of Asia Editor at Seatrade magazine and China correspondent for Supply Chain Asia. His work has also appeared in The Economist, The New York Times, The Sunday Times and The International Herald Tribune.


  1. Any experts out there want to weigh in on what happens if one or more of these sink? Especially if it’s near the coastline or a important fishery?

    1. Very little, molten salt reactors have built in safety features (mainly due to the laws of physics).
      Even if the molten salt came in contact with the seawater, you would get a lot of steam as it cooled (mainly non radioactive steam – there is a very small possibility that radioactive particles could be carried by the steam, however they would quickly settle out and sink to the bottom of the sea.
      The bulk of the molten salt would solidify into an inert non soluble lump that could be mechanically recovered.

      Remember, this is a worst case event where someone purposely damaged the containment vessel And sunk the ship.

      Molten salt reactors are supposed to be walk away safe, ie if you cut all power to the reactor and walked away the reactor would safely shut down.

      The reason that governments did not develop them further in the sixties was that they are very poor reactors for creating weapons grade fuel and they wanted one program for both their weapons development and their civil power. MSR’s are not that.

      A further benefit of MSR’s is that they are supposed to burn 80%. Plus of their fuel whereas normal nuclear power stations are doing well to burn 5% before the fuel has to be reprocessed.

    2. A big chunk of halide salt doesn’t dissolve very fast in an already salty ocean. Molten at elevated temperature. Solid at room temp.
      Fetching is easy if required. A missle makes for more solid spread out. All nuclides from variable splitting are dissolved in the solid salt.

    3. Water is very good at blocking radiation which is why it is used in reactors to slow down the neutrons, Steve Novella said in a Skeptic’s Guide to the Universe podcast that a person could swim at the top of the tall water tanks without harm, I don’t know if scientists have studied the wreck sites of sunk Soviet nuclear powered submarines, however I also don’t know if many people will feel safe on a nuclear powered cruise ship.

  2. Superb news indeed. This is the future for shipping. Meets all emission criteria of now or future.

  3. Rosatom built a floating nuclear power plant with two small modular reactors based on the design from icebreaker ships which has been generating electricity in Chukotka Russia since Dec 2019.

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