According to the new study by the Norwegian classification society DNV, nuclear propulsion is not a panacea, but a high-risk and simultaneously high-yield technology.
If the obstacles regarding safety, the regulatory framework, and social acceptance are overcome, nuclear energy could form the backbone of a zero-emissions fleet.
Specifically, nuclear propulsion can offer stable energy costs, high autonomy, independence from fuels, and near-zero emissions.
However, the technology is accompanied by challenges of safety, regulatory complexity, and social acceptance.
A key chapter for the adoption of nuclear technology concerns the required cost.
DNV’s analyses show that if the cost of a reactor falls below 18,000 dollars per kW, the technology can compete with conventional fuels in a full decarbonization scenario by 2050.
At a lower cost (<8,000 /kW) it will be advantageous even without the strict environmental constraints.
The use of prefabricated, standardized units (modular design) can significantly reduce cost and accelerate licensing.
In parallel, digitalization and automation can limit human resources and improve efficiency.
As an indication, DNV estimates that a commercial ship equipped with a 30 MW reactor would require an investment of 250-350 million dollars, but with a lifespan of 20-25 years (reactor core) and an operating cost up to 60% lower than that of an LNG-fueled ship (from 35,000-60,000 /day to 14,000-24,000 /day, mainly due to /minimal fuel cost and lower maintenance requirements).
The economic equation therefore depends less on fuel and more on the scale of investments, standardization, and regulatory risk.
The first nuclear-powered commercial ships -such as the Savannah (USA), the Otto Hahn (Germany), and the Mutsu (Japan)- proved the technical feasibility, but not the viability.
Despite their successful operation and high costs, the large crew requirements and lack of infrastructure led to the abandonment of the idea for over four decades.
Today, however, the conditions have changed.
The IMO’s 2050 net-zero emissions targets, energy insecurity, and the rapid progress of small modular reactors (SMRs) are making nuclear fuel relevant again.
In this context, new generation reactors (Generation III+ and IV) and SMRs are changing the game.
They are more compact, feature passive safety systems, do not require continuous cooling or a specialized large crew, while the operating duration without refueling can reach or exceed a decade.
Essentially, the alternative reactor types being studied for shipping include molten salt reactors (MSR), lead-cooled fast reactors (LFR), which avoid the risks of high-pressure systems, and Heat-Pipe reactors, which promise structural simplification and minimal maintenance needs.
As highlighted in DNV’s white paper, the challenges are not limited to shipbuilding but extend to the entire nuclear fuel cycle – from uranium production and enrichment to waste management.
To gain credibility and social acceptance, the maritime industry must create an autonomous maritime “cycle” for fuels, which would include: safe storage and transport of enriched fuel, specialized ports and shipyards for refueling and decommissioning, and mechanisms for waste management and reuse.
The management of spent fuels is considered the biggest obstacle. DNV emphasizes that without a clear regulatory framework for storage and disposal, no commercial operating license can be granted.
Based on the same elements, the introduction of nuclear technology in shipping brings two worlds with completely different logics face to face.
On one hand, the maritime regulatory framework, based on international cooperation (IMO, SOLAS, MARPOL), and on the other, the nuclear one, which is strictly national and centrally regulated (IAEA, national regulatory authorities).
DNV points out that a dual regulatory system is required – a “maritime-nuclear grid” that would include the IMO for safety and operational standards, the International Atomic Energy Agency (IAEA) for fuel and protection issues, and the respective classification societies which can act as technical certification bodies.
As such a framework does not exist yet, the Norwegian classification society proposes the creation of a Nuclear Energy Maritime Organization (NEMO), which would coordinate responsibilities and ensure mutual recognition of licenses between states.
Beyond technical specifications, social acceptance remains the most uncertain factor.
The concept of a nuclear-powered containership or cruise ship raises concerns about accidents, terrorism, or pollution.
According to the study, to overcome these fears, it is suggested -among other things- passive safety systems that would operate without human intervention, autonomous monitoring and remote control via satellites, cybersecurity as an integral part of the design, but also transparency campaigns and public information.
