MOLTEN SALT REACTORS Salt and the Earth? Often touted as key to a new generation of onboard power generation, molten salt reactors are still at an early stage of development. E&H Marine delves into some of the key issues still to be fully explored WORDS: STEVIE KNIGHT IMAGES: CORE POWER, ULSTEIN M olten salt reactors (MSRs) continue to gain interest as a potential means by which to decarbonize the maritime industry. These designs are a long way from the Bruce or Zaporizhzhia leviathans that marked milestones in the evolution of reactor technology. They are far smaller, modular and much more efficient, according to pro-nuclear pundits. Furthermore, they could roll off a factory line. But the PR somewhat fudges reality. It’s not unusual to see thorium, one of the potential MSR fuels, described as an abundant, naturally occurring metal with low radioactivity. There is no mention, however, of the uranium (or plutonium seed) that’s needed to make it fissile, creating much more long-lived U-233. In fact, while you might see bland references to ‘molten salts’ of various kinds, Curtin University physics professor Nigel Marks points out that “all of them have fissile material, like uranium, in their core”. That is, Marks explains, just the nature of the technology. Likewise, these MSRs are also often described in press materials as ‘proven’. This is fundamentally untrue; as of 2023 there has only been a single working lab prototype, at Oak Ridge National Laboratory in Tennessee, USA. That doesn’t mean MSRs wouldn’t be extremely useful in helping maritime (and other industries) climb out of a climate-change hole. For example, Ulstein’s Thor concept (which won the Electric & Hybrid Marine Award for Concept Vessel Design of the Year in 2023) could in theory act as a mobile charging station for fully electric cruise ships, or be adapted for other recharging applications. Then there’s what Giulio Gennaro, technical director for Core Power, calls “reverse cold ironing”. If a nuclear ship is plugged in at berth, instead of consuming electricity it could be feeding the port. So as well as powering the cranes involved in its unloading, the ship could charge other vessels or supply the local grid. Furthermore, it’s thought that ports might be as interested in having their own floating power plants – thereby possibly getting around certain zoning restrictions. This could act as a charging station as well as a backup for fluctuating renewables, to ensure a stable power supply. Also, given the steady ‘always-on’ output, energy could be diverted to other port users. A large enough MSR could also 10 // January 2024 // ElectricHybridMarineTechnology.com