View ahead for nuclear ship propulsion

Changing attitudes towards nuclear power are reflected in accelerating engagement by maritime stakeholders with the potential of small modular reactors.

Newly granted International Maritime Organization NGO status for the Nuclear Energy Maritime Organization (NEMO) sees shipping’s global regulator join the growing spread of stakeholders who include small modular reactors (SMRs) in the net zero emission future of vessel propulsion. The International Atomic Energy Agency (IAEA) has invited NEMO to attend General Conference sessions as it heads towards launching ATLAS (Atomic Technology Licensed for Applications at Sea) – its initiative to develop regulatory structures for nuclear propulsion and floating nuclear power facilities.

NEMO’s growing constituency coincides with wider changes in political attitudes, with Germany withdrawing opposition to French efforts to treat nuclear power as equivalent to renewables under EU law, and policies blocking development under re-evaluation in Belgium and Denmark. In a significant pivot, the government of Japan plans to reactivate 14 of its 54 nuclear reactors¹. Elsewhere, the World Bank is lifting a ban on nuclear financing, in response to surging developing world electricity demand.²

NEMO’s onboarding as an NGO at IMO by July 2025 is nonetheless rapid, for a grouping established just last year. The regulator’s receptiveness should therefore also be seen as representative of a maritime industry whose technical experts have already been on the move on nuclear-powered ships.

Norway’s NuProShip (Nuclear Propulsion in Shipping) aims to develop a commercially viable zero-emission technology for deep-sea ships.
Image credit - Adobe Stock — Norway’s NuProShip (Nuclear Propulsion in Shipping) aims to develop a commercially viable zero-emission technology for deep-sea ships. Image credit - Adobe Stock

In February, Lloyd’s Register, Core Power and marine insurer NorthStandard published a policy framework for the UK Government to support the installation of SMRs on commercial ships. Italian society RINA, meanwhile, has presented views on applying SMRs to superyachts. Furthermore, plans from South Korea's HD Korea Shipbuilding & Offshore Engineering for an SMR-powered 15,000 TEU container ship have secured Approval in Principle from ABS and subjected to a HAZMAT study by DNV.

In June, IMO’s Maritime Safety Committee (MSC110) agreed to begin updating legacy regulations governing nuclear-powered ships, tasking the Sub-Committee on Ship Design and Construction (SDC) to start work on a framework to bring nuclear propulsion into the mix to achieve net-zero emissions by around 2050. Critically, an updated Code of Safety for Nuclear Merchant Ships will look beyond Pressurized Water Reactor (PWR) systems with direct steam cycle propulsion to incorporate innovations such as the All-Electric-Ship concept.

Ships in nuclear power play

A panel at this year’s Nor-Shipping³ offered a timely progress report on the practical progress that is being made to base nuclear ship propulsion on a new generation of SMRs. Norway’s three main political parties do not rule out nuclear power as a potential route towards decarbonization goals, while a 2023 survey suggested 51 percent of Norwegians support the development of nuclear power⁴.

The Nor-Shipping session, organized by WISTA Norway and Maritime Cleantech, brought together ship manager OSM Thome, builder VARD, insurer Gard and Emerald Nuclear to highlight the strong impression being made in Norway by fast-developing SMR technology.

Hallgeir Juliebø, Chief Commercial Officer, Emerald Nuclear Inc., told delegates that ships offered a better opportunity to pioneer SMR technology than land-based facilities. He sharply contrasted ‘old’ nuclear technology – which had a “total disregard for money”, “all the time in the world”, governments as its client, and tended to be “first of a kind” – with ‘GEN IV’ SMR solutions.

Emerald Nuclear Norway had been established to “build a bridge between the marine industry and nuclear business,” said Juliebø. A first system – a microreactor of around 5MW using TRISO fuel particles - would be ready for shipboard installation by 2029.

Nuclear propulsion could make a significant contribution to maritime decarbonization by 2050.
Image credit - Adobe Stock — Nuclear propulsion could make a significant contribution to maritime decarbonization by 2050. Image credit - Adobe Stock

With the business model based on clients “buying megawatts not the reactor”, Juliebø also claimed that bringing the reactor to market “without taking into account CO2 emissions” would deliver a solution offering pricing “at marine diesel plus 20 percent”.

Håvard Vollset Lien, Vice President Research & Innovation, Vard Group advocated the nuclear option in the context of a predicted scarcity of other sources of green energy in the years ahead, and the likelihood of alternative fuel prices “going to go sky high”. Competition from land-based industries to replace polluting fuels would add impetus to nuclear ship propulsion, he said.

Economic evaluation

Offering especially on-point insights to commercial shipping was Torbjørn Lie, OSM Thome Business Development Manager and a prime mover in the ship manager’s EVIGO Green Services Division.

High-temperature gas-cooled reactors, liquid metal-cooled fast reactors, and molten salt reactors are the three most promising options for nuclear ship propulsion.

Lie spoke as Editor of the ‘Advanced Nuclear in Maritime Report’⁵ – a feasibility study facilitated by DNV and submitted to Norway’s Green Shipping Program in May based on two years of work and input from 25 companiesⁱⁱⁱ. It focuses on vessels with installation requirements between 5 to 15 MW.

It was publication of this report which prompted Professor Jan Emblemsvåg, Norwegian University of Science and Technology (NTNU) to remark: “We strongly believe that by 2035, the first commercial ship with advanced reactors can be in operation.”

The study takes its lead on technical matters, regulation, GEN IV competitiveness (with HFO) and impacts on ship design from the earlier Nuclear Propulsion for Merchant Ships I (NuProShip I) project. It therefore homes in on high-temperature gas-cooled reactors, liquid metal-cooled fast reactors, and molten salt reactors as the three most promising options for nuclear ship propulsion. Some reactor designs can operate through the ship’s lifetime without refueling.

In addition, the report is a “techno-economic and safety analysis of advanced nuclear energy technology as an initial step towards potential implementation”, said Lie. Its content will feed into the development of new reactor concepts by the end of 2025, for subsequent tailoring for ship types and different operating profiles within NuProShip II.

With appropriate investments and regulatory support, it suggests nuclear propulsion could make a significant contribution to maritime decarbonization by 2050.

Lie predicted that initial moves towards nuclear ship propulsion may need to take place in the space left for alternative designs in regulations, with realistic scenarios for practical application involving a single jurisdiction, bilateral agreements and/or fixed routes. However, the commercial shipping case for nuclear was especially powerful, “given that 85 percent of the 1 billion tonnes of carbon emissions we are supposed to eliminate by 2050 comes from deep sea ships of above 5MW.”

Based on the lower of two reactor CAPEX/OPEX/annual leasing cost models, where a ship’s Specific CAPEX is USD4,000/kW and remains stable while alternative fuel prices rise as GHG targets approach, “there can be an economic case for nuclear propulsion”, according to the OSM report. Furthermore, payback for an SMR could be achieved in 10-15 years – half the period for a conventional nuclear project.

Nuclear conversion

Part of the report focuses on a cooperation involving Maran Shuttle Tankers, NTNU, ABB and OSM Thome, Brevik Engineering to develop a preliminary feasibility study evaluating the potential for converting the 67,383 GT tanker Altera Wave to nuclear power.

The conversion proposal involves removing two generator sets and relocating some equipment to make space for two nuclear reactors, turbines, and a heat exchanger, with the existing generator sets integrated with the nuclear setup. Power would be provided by a Micro Modular Reactor (MMR), developed by Ultra Safe Nuclear Corporation – an HTGR with a thermal power of 15-45 MWt (5-15 MWe).

I think nuclear will be part of the [maritime] energy mix. How big – it’s hard to say; that will come down to cost.

Initial weight and stability assessments indicate that the conversion is feasible, with “no showstoppers identified to the retrofit and integration in the engine room layout”, the report says. However, as the report also acknowledges, insurance is a “showstopper”.

Andreas Brachel, Vice President, Head of Environmental Claims, Gard struck the expected cautionary note from insurers in his Nor-Shipping panel remarks. To be insurable, he reflected, nuclear propulsion will first need a regulatory framework that identifies who is liable and how to cap liability.

“Having said that I think there is some appetite for insuring this as a commercial product,” he added. “I think nuclear will be part of the [maritime] energy mix. How big – it’s hard to say; that will come down to cost. Technically we depend on the classification societies; as long as they approve and if all other things are in place, we are likely to approve of taking the risk.”

Recent progress in 4th generation nuclear technology has now opened new horizons also for merchant marine.
Image credit - Adobe Stock — Recent progress in 4th generation nuclear technology has now opened new horizons also for merchant marine. Image credit - Adobe Stock

ABB’s standpoint as technology supplier

While nuclear-powered vessels have a long and successful history in naval and icebreaker operations, recent progress in 4^th generation nuclear technology has now opened new horizons for commercial shipping. The fast pace and concentrated development of efforts are significant as the maritime industry moves forward in its global pursuit of decarbonization.

Considering the recent advances in nuclear technology and the active participation of a wide range of stakeholders, the question has shifted from whether an opportunity for shipping will arise to when it will materialize.

Strong regulatory progress is noted by ABB with appreciation, especially the recent IMO MSC 110 decision to initiate the revision of the Code of Safety for Nuclear Merchant Ships and relevant parts of the SOLAS Convention⁶. We also acknowledge the significance of the IAEA project ATLAS (Atomic Technologies Licensed for Applications at Sea)⁷ and the important supportive work carried out by NEMO (Nuclear Energy Maritime Organization)⁸.

Considering the recent advances in nuclear technology and the active participation of a wide range of stakeholders, the question has shifted from whether an opportunity for shipping will arise to when it will materialize. And when it does, ABB Marine & Ports will be ready to provide advanced electric propulsion and power plant solutions to meet the needs of the nuclear-powered merchant marine.