“We will see nuclear ships on specific trade routes sooner than many people currently anticipate,” said Lloyd’s Register CEO Richard Sadler. The organisation has been an independent service provider to the shipping industry for 250 years. There is the potential for market-based measures for controlling carbon dioxide emissions, while the entry into force of strict International Maritime Organisation controls in 2020 provides a firm deadline against which the industry can weigh the benefits of a range of technology enhancements and fuel options. But with no clear technological fix to lower emissions using traditional diesel or LPG fuels, nuclear energy is emerging as a practical option.
In response to its members’ interest in nuclear propulsion Lloyd’s Register has recently rewritten its ‘rules’ for nuclear ships, which concern the integration of a reactor certified by a land-based regulator with the rest of the ship. A draft of the rules was put before Lloyd’s technical committee two weeks ago and this represents a further step towards an international regulatory regime to ensure worldwide safety in a potential nuclear shipping sector.
The new program of joint research (Marine and energy consultants BMT Group and Enterprises Shipping and Trading have joined with start-up small reactor firm Hyperion and Lloyd’s Register to “investigate the practical maritime applications for small modular reactors.”) is meant to produce “a concept tanker ship design based on conventional and modular concepts,” said Lloyd’s. It noted that “Special attention will be paid to analysis of a vessel’s lifecycle cost as well as to hull-form designs and structural layout, including grounding and collision protection.”
Nuclear power looked set for a maritime role in the 1960s thanks to early vessels like the Savannah and Otto Hahn, although in the end the Savannah worked for only ten years and the Otto Hahn was repowered with diesel engines after nine years. The Japanese-built Mutsu operated from 1970 until 1992 but none of these ships was a commercial success.
A luxury liner has the power demand curve of a town, including peaks at morning and evening mealtimes. Conceivably a 100 MWe nuclear power system could take the baseload role with smaller diesels for peak load and back-up.
Transporters moving large cargoes like raw materials on point-to-point routes could run much faster with the extra power and low emissions from a nuclear reactor. A frequent service could be run by fewer vessels, mitigating the extra capital cost.
Existing conventionally powered vessels could attach to a nuclear-powered tug for emissions-free passage across oceans.
What about the ports?
Nuclear powered vessels could be the subject of controversy and this would seem to make a nuclear cruise liner concept difficult due to passenger and port acceptance. However, a point-to-point cargo service would need only agreement from two states and the supertug could remain in international water. Another idea is to create a large nuclear vessel with a conventionally powered detachable section to take cargo to port.
There remain about 200 small reactors at sea in military fleets but this technology cannot easily be transferred to the civil sector due to the requirement of using low-enriched uranium (LEU). High-enriched uranium allows more compact reactor designs with weight and controllability benefits.
The reactor of the Hyperion system uses LEU and measures about 1.5 metres by 2.5 metres. It would produce about 70 MWt – enough for about 25 MWe for propulsion. Its ‘battery’ design simplifies refuelling to a swap-out operation every 8-10 years with the possibility of managed lease arrangements similar to aircraft engines.
However, incorporation of any reactor in a ship would require extensive radiation shielding, consideration of impact protection. A step change in crew training would be required and there is a strong case for crew to be supplied by reactor vendors.