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Just how viable is nuclear-powered shipping?

Just how viable is nuclear-powered shipping?
Although Lloyd’s Register made brief mention of nuclear-powered vessels at its Future Fuels conference, global strategic marketing manager Luis Benito relegated the possibility until after 2030: “Nuclear is not popular, although it is available,” he said. “Maybe in the distant future the public perception will change about using nuclear as fuel.”

Members of LR stress that considering nuclear power as an option isn’t necessarily the same as advocating it. “Some of our competitors have superficially dismissed it,” says LR marine communications manager Nick Brown, “but as a classification society, we only the handling the engineering - it’s for governments, not us, to decide whether or not to use nuclear.

To date nuclear power in relation to commercial shipping has been restricted to a small number of icebreakers, however, it has been studied by some commercial owners. In 2009, Cosco had entered talks with China’s nuclear authority to develop nuclear-powered commercial vessels. "As they are already onboard submarines, why not cargo ships?" asked Wei Jiafu, Cosco's then-president and ceo at that year’s Marintec China. The project was later abandoned in the wake of Japan’s Fukushima disaster.

In 2010, a coalition of LR, Hyperion Power Generation, British designer BMT Nigel Gee and Greek ship operator Enterprises Shipping and Trading initiated a feasibility study into nuclear powered ships: “We strongly believe that alternative power generation is the answer for shipping transportation,” the head of Enterprises, prominent Greek shipowner Victor Restis, said at the time. At time of writing, the project is “still ongoing”, according to Brown.

Often one of the biggest objections to nuclear power is the misconception that nuclear reactors can be made to detonate in a thermonuclear blast. However, as senior researcher of DNV GL’s Greener Shipping project Christos Chryssakis explains: “In contrast with general perceptions, the nuclear security risks during operation are actually quite limited. As the nuclear chain reaction is started in the reactor, the fuel becomes highly-radioactive and hence self-protective.

“Any attempt to remove fuel from the reactor would encompass a life-threatening situation,” says Chryssakis. “The ‘best’ that any perpetrators may accomplish is radioactive releases, or threats thereof. Fuel characteristics, fuel geometry, and safety controls would prevent the reactor from becoming a ‘nuclear bomb’. While releases could become severe with possible exposures in the vicinity of the ship, damage would be very small compared with that resulting from a nuclear explosion.”

“Leakage of coolant can be the cause of severe accidents due to its high pressure and high temperature, as well as radioactive contamination,” says Chryssakis, explaining that vessels incorporating nuclear propulsion would have to be equipped with sufficient radiation shielding, measures to stem the leakage of coolant, and back-up diesel propulsion for emergencies. “Navy experience has proven that reactor reliability is high with modern designs.”

Indeed, assuming nothing goes wrong, which, in the vast majority of cases for many hundreds of nuclear-powered submarines and warships it does not, nuclear reactors can last 25 years with comparatively low maintenance and no need to refuel. “The main technical barrier we see for nuclear propulsion is related to handling, storage and recycling of used nuclear fuel.”

What about other zero-carbon propulsion methods? “While batteries are increasing in size… they cannot match the requirements for propulsion for modern large ocean-going ships,” says Chrissakis. “Hydrogen is problematic for three main reasons: vast amounts of energy and infrastructure would be required for production; storage on board requires much larger space than conventional marine fuels; and the fuel cell technology is not compact and reliable enough yet.”

Although the risks posed by widespread adoption of nuclear propulsion are, for many, unthinkable, it is one of a very short list of options for zero-carbon shipping. “If society gets serious about cutting emissions, it’s one option which will have to be considered,” Brown concludes.