Nuclear power might become a prominent fuel source for shipping someday, but the road to viability is daunting, the American Bureau of Shipping says.

The classification society has received $800,000 from the Department of Energy (DOE) to study barriers to using nuclear energy to propel cargo ships, as previously reported in TradeWinds.

But it acknowledges that the difficulties are many before it even starts looking at the possibilities.

“There are a range of safety, regulatory and operational challenges to be addressed before the technology is viable for commercial application at sea,” senior vice president of engineering and technology Patrick Ryan told TradeWinds.

“Aside from the technology issues, there are others that will require careful consideration, such as nuclear maintenance at shipyards, crew training and end-of-life decommissioning.”

ABS plans to use the grant to develop models of ship-friendly reactors and develop an industry advisory on using nuclear power.

Development and testing will take place at the DOE’s National Reactor Innovation Center at the Idaho National Laboratory.

ABS welcomes the support but is fully aware that there are regulatory hurdles to overcome, no matter what designs are drawn up.

Ryan said any proposed concepts would need engagement and approval from flag states, classification societies and coastal states.

They will also need approval from the International Maritime Organization and International Atomic Energy Agency.

“As with all new technologies, there will be safety challenges, which will require not only engineering rules and requirements for the design, but also operational strategies and training to address,” he said.

The idea has received widespread interest from shipowners, but a major concern is what to do with nuclear waste after the reactor expires.

“All power options as we move forward toward sustainability goals have both positive and negative components,” Ryan said.

“It is a great opportunity to work to address the challenges of end-of-life concerns for nuclear fuels.”

One option may be to burn spent fuel to provide additional energy and reduce the amount of waste.

Despite the challenges, Ryan expects nuclear to “play a key role” in powering cargo ships one day, although he would not go so far as to call it the industry’s fuel of the future.

“This assessment goes beyond purely considering installed nuclear power for primary propulsion, to include terrestrial or offshore power generation that can provide alternative energy sources for hybrid/battery applications, power and heat for synthetic or hydrogen fuel production, and direct power for offshore applications,” he said.

In other words, offshore vessels or smaller cargo vessels designed for short sea shipping are less likely to have nuclear solutions installed on board, but they could still benefit from the use of nuclear power to produce alternative fuels or electrical power in a battery system.

The NS Savannah, the first commercial nuclear cargo vessel, sails in San Francisco Bay en route to the 1962 World’s Fair in Seattle. Photo: US National Archives & Records Administration

“These are questions that still must be answered by rigorous engineering research and technology development,” Ryan said.

He was vague on whether using nuclear power on a cargo ship is financially viable, but did say that ABS will look to shipowners to come up with financial models to determine that.

Another important consideration for using nuclear power to propel cargo ships is how big these reactors might be, at the expense of money-making tonnage.

“Reactor size would reflect the power requirements of the vessel,” he said.

“We have seen in legacy studies that the reactor compartment, together with all of its components, could weigh up to three or four times more than a conventional propulsion plant of the same power.”

A cooling system and radiation shields would make the reactor even heavier. For example, there is 2,000 tonnes of shielding on the 13,600-gt ABS-classed NS Savannah, a nuclear-powered cargo ship built for the US Maritime Administration in 1961.

“New technologies hold a promise for a more compact design, with less water and steel required,” he said.

“Understanding these requirements, especially with plants built on revitalised technologies such as molten salt, will be part of the ABS study.”

The Department of Energy is funding ABS’ research into nuclear-powered shipping. Photo: DOE