MARINE NUCLEAR APPLICATIONS | COVER STORY
Left:
In the joint study by ABS and HEC a floating platform named Navigator was designed with supply to the onshore grid in mind Source: ABS
no need for fuel or high radioactive waste to be handled on board.
Feasibility study for an LNG carrier ABS also worked with HEC on the high-level design of a standard LNG carrier to illustrate how one type of advanced nuclear fission technology could be applied for shipboard power in the future, with an emphasis on what aspects of ship and reactor design may require further investigation to guide the development of the integrated technology and regulatory framework. The main conclusion of this study was that nuclear power would be a supportive means of drastically abating shipping emissions, but that significant hurdles remain in public perception and international regulations before this can be achieved. The modular reactor philosophy imposes significant
restrictions on ship design. The modularity concept imposes a fixed maximum SMR power output per reactor, corresponding to a set lifespan of its core. It is advantageous if the nuclear power plant equipment and fuelling lifecycles align with the vessel’s life. Access to suitable shipyards or other support facilities and the physical removal of the reactors are key challenges, which would be simplest to avoid by addressing the issues in the design stages. It is possible to operate an SMR at a lower constant power level such that its core will last longer. This may cause the reactor end-of-life to not line up with the ship’s standard drydocking schedule, thus imposing significant additional operational costs. This means that SMRs would be better suited for just a
few sizes per ship type (mostly larger ships). In the design presented in the study, the SMR is considered to have an output capacity of 17.5 MWe associated with a core lifespan of five years. This matches well the total power requirement of a 147k LNG carrier, imposing the use of two reactors and a core
m3
switch at each special survey. However, if the same SMR were considered for a QMax LNG Carrier (262k m3
) with a
total energy need of approximately 56 MW, four SMRs would be needed, operating at around 80% of their maximum power.
This would imply a core switch approximately every six
years and three months, which would represent the primary driver for service scheduling. This SMR feature may impose limits to ship capacity that can be offered to the market.
At the same time, the ability of nuclear power plants
to tolerate higher accelerations due to ship motions and vibrations can allow for flexibility in the overall design. While there are significant safety benefits to keeping the plants at midships, for specific vessel types like oil tankers and LNG carriers, the midships location would not be feasible or would significantly penalise cargo capacity. The degree of redundancy required by a nuclear-powered
vessel may be higher than a more conventionally powered vessel for safety, which causes a decrease in performance. The nuclear vessel design presented has two separate power, propulsion and steering plants, which provide a high level of redundancy compared to no redundancy typically accepted of single screw vessels driven by marine diesel engines. Opportunities for optimisation exist on many levels for future design iterations. However, both this study of nuclear-powered commercial
vessel designs and the nuclear-powered cold-ironing analysis also concluded that the maturity of advanced nuclear technologies that may be implemented for these applications is currently low. Therefore, the level of detail provided in the studies is limited to engineering information available from the design of terrestrial applications for engineering postulation and recommendations for future design optimisation.
Outlook for nuclear in marine applications Nuclear energy has the potential to be a disruptor for the maritime sector. The ABS focus is on bringing together major players in marine and offshore design with designers of nuclear systems. ABS can help facilitate filling knowledge gaps that nuclear power companies may have around marine and offshore and vice versa. With the feasibility demonstrated for small nuclear
reactors onboard large container ships, gas carriers and offshore platforms, it is likely that regulation and reactor licensing will prove the primary driving force in realising full-scale projects. With renewed interest in building new technologies that
are feasible for the marine sector, it will be up to regulators to support the ambition of reducing carbon emissions by enough to meet 2050 targets. While the regulatory landscape continues to develop, both modular system providers and vessel designers are encouraged to establish further joint industry projects that can further investigate both challenges and opportunities. ■
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