Nuclear ship propulsion is mature for navies and for Russia's Atomflot icebreaker fleet, but commercial cargo shipping remains pre-commercial. The IMO agreed in 2025 to rewrite its 1981 nuclear merchant ship code with adoption targeted around 2030, while HD Hyundai, CSSC and Core Power pursue molten salt and sodium fast reactor designs.
What it is and how it works
Nuclear ship propulsion uses a reactor as the heat source for a steam cycle. Naval vessels and Russia's icebreakers run pressurised water reactors, such as the RITM-200 on the Project 22220 icebreakers, driving steam turbines or turbo-electric drives. The commercial revival is built around a different generation of reactors: molten salt designs from Core Power, Seaborg and the CSSC thorium programme, the TerraPower Natrium sodium fast reactor, and HALEU-fuelled small modular reactors, nearly all paired with electric propulsion. Developers choose these concepts for low operating pressure, walk-away safety and refuelling intervals measured in years. That choice collides with the rulebook, because the IMO's 1981 Code of Safety for Nuclear Merchant Ships assumes a pressurised water reactor with direct steam propulsion.
Why it matters now
Nuclear is the only propulsion option that removes fuel-intensity exposure outright, but every announced commercial timeline lands beyond the 2028-2030 horizon of the IMO Net-Zero Framework and EU carbon rules. The regulatory track has started moving. At MSC 110 in June 2025 the IMO agreed to revise the 1981 code and relevant SOLAS provisions, judging the code outdated and a barrier to advanced reactors (NucNet). SDC 12 in January 2026 agreed a multi-year work plan for SOLAS Chapter VIII and the code using goal-based standards and set up a correspondence group; Lloyd's Register notes SOLAS will not be amended at this stage. Adoption is reported to be targeted for 2030 (AJOT).
Key players and products
Rosatom's Atomflot operates eight nuclear-powered vessels, with the Project 22220 icebreaker Chukotka, launched in November 2024, to be the ninth (TASS). The lead Project 10510 Leader icebreaker Rossiya is scheduled for delivery at the end of 2029 after earlier targets of 2027, and Sevmorput, the only civil nuclear cargo ship, is to be retired and replaced by a diesel container carrier. In Korea, HD Hyundai runs the most advanced commercial programme: ABS and HD Hyundai signed a joint development project in March 2026 for a 16,000 TEU container ship with SMRs supplying up to 100 MW (World Nuclear News); Lloyd's Register granted approval in principle in June 2026 for a car carrier with a molten salt reactor developed by HD HHI, HD KSOE, Hyundai Glovis and KAERI (World Nuclear News); and TerraPower, HD Hyundai and Hyundai E&C agreed in August 2026 that HD Hyundai will manufacture major Natrium reactor equipment, targeting 2-3 vessels a year (PortNews). Samsung Heavy Industries completed the CMSR Power Barge design with Seaborg and received ABS approval in principle in January 2023. CSSC Jiangnan unveiled a 24,000 TEU thorium molten salt container ship in December 2023, since scaled to about 14,000 TEU with a 200 MW thermal reactor.
Figures that matter
| Metric | Value | Source type | Source |
|---|---|---|---|
| HD Hyundai/ABS JDP container ship | 16,000 TEU, SMRs up to 100 MW | trade-press | World Nuclear News |
| Atomflot nuclear vessels | 8 in operation, Chukotka ninth | trade-press | TASS |
| Leader icebreaker Rossiya | 120 MW, delivery end-2029 | trade-press | TASS |
| CSSC/CNNC thorium box ship | about 14,000 TEU, 200 MWt | trade-press | — |
| Core Power Liberty programme | orders 2028, market mid-2030s | vendor | Core Power |
| IMO Nuclear Code revision | adoption targeted 2030 | regulatory | IMO via AJOT |
| SHI CMSR Power Barge | 2-8 x 100 MW, ABS AiP 2023 | trade-press | World Nuclear News |
Core Power's Liberty programme, announced in February 2025, aims to mass-produce floating molten salt reactor plants in US shipyards, with first orders anticipated in 2028, market entry by the mid-2030s and ship propulsion as a second phase (World Nuclear News); its chief executive's expectation of first nuclear ship orders before the end of the decade is a company projection.
Developments 2023-2026
- 2023: ABS approval in principle for the Samsung/Seaborg CMSR Power Barge in January; CSSC unveils the thorium container ship at Marintec China in December.
- 2024: Chukotka launched in St Petersburg in November; Atomflot announces Sevmorput's retirement.
- 2025: Core Power launches Liberty in February; MSC 110 agrees in June to rewrite the nuclear code.
- 2026: SDC 12 agrees the work plan in January; the ABS and HD Hyundai project follows in March; Lloyd's Register grants the car carrier AiP in June; the TerraPower partnership is signed in August; TradeWinds reports in October that the HD Hyundai alliance with KEPCO E&C, Hyundai E&C and the Korean Register is moving toward a testing stage (TradeWinds).
Outlook
With IMO instruments due around 2030, Korean testing in the late 2020s and Core Power's floating plants in the mid-2030s, a first commercial nuclear merchant ship in service is unlikely before the early to mid-2030s even for the leaders. First commercial cargo ship orders before 2030 remain a developer projection rather than a confirmed plan.
