NRG Pallas WP1 Work Summary - Hydrogen production, NTP, Maritime
Publish date: 19/05/2026
NRG Pallas' Bart Verdonschot summarizes the WP1 work regarding the use of nuclear power in various sectors, notably hydrogen production, nuclear thermal propulsion and maritime applications.
Hydrogen production
Hydrogen plays a key role in the world economy today and its importance is expected to continue to grow as its role in the energy transition develops. The increase in demand and the increasing push to reduce carbon emissions in the economy is expected to push for the rapid growth in low carbon hydrogen production in the coming decades. One of the possible routes is high-temperature hydrogen production, which has lower technological readiness levels compared to conventional electrolysis, but offers possible advantages such as higher efficiencies. The main low carbon, high temperature hydrogen production methods being developed are high temperature steam electrolysis and thermochemical cycles.
To meet the energy demand for these high-temperature hydrogen production methods, nuclear reactors are of increasing interest. Generation IV reactors such as High Temperature Gas-Cooled Reactors (HTGR) and Molten Salt Reactors (MSR) are particularly interesting due to their higher core outlet temperatures compared to light water reactors. This possibly allows more direct and simpler integration between the nuclear power plant and hydrogen production plant. Research has shown, however, that using light water reactors for high-temperature hydrogen production is technically feasible and potentially economically viable with the inclusion of heat augmentation, allowing the steam produced by the reactor to reach the required temperatures for the hydrogen plant. Essentially, this means that all nuclear reactor types are potentially interesting for providing heat to hydrogen production processes.
Connecting nuclear power plants to various high temperature hydrogen production techniques comes with various challenges depending on the technologies involved. The main challenges are related to how the systems should directly connect with each other and reaching the required temperature range for hydrogen production to run as efficiently as possible. Additionally, if no heat augmentation is used, only a fraction of the reactors currently in development can be used for high-temperature hydrogen production, specifically the highest temperatures HTGRs. Lastly, exact requirements for these systems to safely operate and be economically feasible are not yet fully understood as many of the technologies are not deployed on a commercial scale yet.
(1) Impression from an IAEA report: Hydrogen Production with Operating Nuclear Power Plants, Business Case. May 2025. Available online: hydrogen-production-with-operating-nuclear-power-plants.pdf
Nuclear Thermal Propulsion
Nuclear technology has the potential to support space exploration and application. Examples are long-term power sources on satellites and moon bases, and an energy-dense propulsion method for spaceships. Nuclear power sources are particularly interesting in cases where commonly used solar
panels have reduced efficiency, such as spots where direct sunlight is often interrupted (for example on the moon), for missions far away from the sun or for orbital transfers (interplanetary travel) that have massive energy requirements. Specifically, the last point has received increased attention in recent years, with Nuclear Thermal Propulsion (NTP) being one of the main nuclear propulsion methods currently under research. NTP systems utilize a lightweight propellant, usually hydrogen, which doubles as the reactor coolant. The gas is superheated within the reactor core (to > 2500 C) and then expanded through a nozzle to produce thrust. Through this method, an NTP system can compete with conventional chemical propulsion with generally higher fuel efficiency, albeit with a radioactive and more complex propulsion unit. The increased fuel efficiency has the potential to reduce transit times, helping minimize radiation exposure from interplanetary space for manned missions.
While promising, NTP systems have several drawbacks compared to chemical rockets. Most critically, although NTP systems were tested on land in the 60s and 70s, few tests have been carried out since with no representative tests in space itself. Compared to the well-understood, non-radioactive and increasingly cheap chemical propulsion methods, the use-case for NTP is shrinking. Additionally, material limitations of the solid core prevent scaling in exhaust temperature with current technologies (which would increase efficiency), and volume limitations on current launch vehicles prevent benefiting fully from the increased fuel efficiency for the low-density propellant.
(2) Drawing of the NERVA nuclear rocket engine. 1970. NASA. Available online: NERVA nuclear rocket engine.
Maritime
Nuclear energy has the potential to become a serious player in the future of maritime logistics, offering an energy-dense alternative to the carbon-heavy propulsion currently used in global shipping. While military naval vessels have used nuclear reactors for propulsion for decades, the transition to civilian application requires a different class of reactors due to more strict regulation and safety constraints. Currently, generation IV reactor concepts such as Molten Salt Reactors (MSRs), High-Temperature Gas-cooled Reactors (HTGRs) and Lead-cooled Fast Reactors (LFRs) have the highest potential to be applied for civilian ship propulsion, mainly due to their inherent safety features and high fuel burnup potential. Nuclear propulsion provides great operational endurance: a nuclear reactor allows a vessel to sail for several years without refueling, enabling continuous zero-emission operation while removing the logistical constraints of traditional fuel supply chains.
However, the application of nuclear in ship propulsion is complex and non-trivial. Next to the general technological challenges of realizing generation IV reactor concepts and the high upfront capital investment, the primary challenge is the complex regulatory and geopolitical landscape. International frameworks are often outdated, fragmented and non-binding, creating uncertainty for reactor developers and operators. Additionally, many commercial ports currently lack legal frameworks or safety protocols to accept civilian nuclear vessels, making standard global routes difficult to establish. Safety and security requirements also diverge from land-based plants, as maritime reactors face unique environmental stresses, mobility related risks, and maritime-specific threats such as piracy. Meanwhile, strategies for nuclear waste management at sea remain underdeveloped. Despite these uncertainties, several initiatives are gaining momentum to realize commercial nuclear ship propulsion on both the reactor development side, such as the Dutch Allseas, as well as on the regulatory side, such as IAEA’s ATLAS program.
(3) Figure from an Allseas article: Allseas pioneers nuclear technology. 5 June 2025. Available online at: Allseas pioneers nuclear technology.