GoKawiilThe shipping industry needs low-carbon fuels if it is to reach net-zero greenhouse-gas emissions by 2050. But options are limited. Batteries can power ferries and vessels for use in harbours, but are impractical over long distances1. Methanol is hard to produce sustainably2. Ammonia is toxic and its supply chain is polluting3. Hydrogen is too bulky and difficult to store safely at sea4.
Nuclear reactors are being eyed as a solution. Atomic energy produces no direct carbon dioxide emissions and avoids the need to store several thousand cubic metres of fuel on board, freeing up space for cargo. Using nuclear power could shorten voyage times by eliminating refuelling stops and attaining higher speeds. It could save a ship owner tens of millions of dollars per ship per year in marine fuel costs and carbon taxes (see go.nature.com/4hs7u3r).
China reins in the spiralling construction costs of nuclear power — what can other countries learn?
A new generation of nuclear-powered commercial ships could be ploughing through the waves in the next decade. Interest from industry and governments is growing. In May, the US Maritime Administration sought public input on a commercially viable, scalable small modular reactor system for marine use. In 2028, London-based Core Power plans to open an order book for mass-produced floating nuclear power plants, with full commercialization in the mid-2030s and nuclear civil ships to follow. In China, the state-owned Jiangnan Shipyard, based in Shanghai, plans to build the world’s first thorium-powered container vessel by 2035.
A 2023 US report estimates that several hundred nuclear-powered merchant vessels (mostly container ships,large bulk carriers and oil tankers) could be operating worldwide by 2050, assuming a 2–5% market share5 (see ‘Commercial shipping goes atomic’). But a merchant ship fitted with a reactor is a mobile nuclear facility that needs to be treated with great care. It could be hijacked, run aground or even come under missile attack.
Source: Ref. 5
Before nuclear-powered ships reach the seas, the world needs to develop robust regulations around them. Engineers, regulators, ports and shipping companies must make these vessels safe and controllable. But current rules are outdated and fragmented.
Two major efforts are under way. In late August, at a ministerial-level event in Washington DC, the International Atomic Energy Agency (IAEA) plans to bring nuclear and maritime regulators together at the launch of its Atomic Technologies Licensed for Applications at Sea (ATLAS) initiative. In June 2025, the International Maritime Organization (IMO) began revising its 1981 Code of Safety for Nuclear Merchant Ships, and expects to adopt a revised code in 2030.
Here we set out what is at stake and call on the IAEA and IMO to link reactor licensing, ship certification, port entry and emergency response into one framework, lest companies, ports and countries implement incompatible systems and a nuclear accident at sea ensues.
From military to commercial use
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