A floating nuclear power plant - off Singapore?

Lim Soon Heng For The Straits Times 4 Oct 16;

The Republic could be a world leader in building small reactors deployed at sea, including in nearby waters
The Fukushima nuclear plant disaster in 2011 left the world with a deep aversion to nuclear power.

However, the approval last month by Britain for the construction of a nuclear plant at Hinkley Point is a symbolic turning point.

Britain will pay £92.50 per megawatt hour of electricity produced (S$0.165/kwhr), rising with inflation, for 35 years, according to the Financial Times.

The price is substantially higher than the prevailing market rate for fossil fuels. The British government must have decided that the premium for the clean energy was worth paying. It is also a tacit acknowledgement that the harvesting of wind, solar and tidal current energies will not meet foreseeable demand.

Nuclear fission emits no pollutants or gases. A gas-, oil- or coal-fired power plant insidiously emits toxins and carbon dioxide, threatening life and destabilising the environment.

According to the Nuclear Energy Institute: "As of May 2016, 30 countries worldwide are operating 444 nuclear reactors for electricity generation, and 63 new nuclear plants are under construction in 15 countries."

In Asia, by 2030, China expects to have 150 gigawatts (GWe) of electricity - Malaysia, 1 GWe; Vietnam, 10 GWe; and Indonesia, 35 GWe. In France, 75 per cent of the energy is from nuclear sources.

Is the nuclear option important for Singapore? Certainly. Ninety- five per cent of Singapore's energy needs are piped from Indonesia and Malaysia in the form of natural gas. The economy's heavy dependence on a single fuel type, and its mode of delivery, makes it vulnerable.

To diversify its procurement strategy, Singapore has built liquefied natural gas (LNG) storage and regasification facilities so that LNG can be shipped in addition to being piped. Storage facilities, including deep caverns and floating tank farms, have been developed.

However, LNG reserves are finite. Nobody is sure how much is left.

Renewable energy, such as solar power, is the only sustainable energy source for this century but the technologies to harness renewables economically still face challenges. Even if they are overcome elsewhere, in Singapore, the challenges will remain.

Solar energy is very costly because it is land-intensive. And renewable energy from hydro, wind and tidal current sources are not that available in Singapore.

THE ONLY VIABLE ANSWER

The nuclear option is the only viable one. However, with an area of 713 sq km, Singapore does not have the space for a nuclear power plant. (For Fukushima, an area within a 20km radius from the plant was declared unsafe, an area 75 per cent larger than Singapore).

Retired Cambridge University don Andrew Palmer, formerly Keppel Chair professor in the department of civil engineering at the National University of Singapore, advocates building a nuclear plant underground. He argues that, in this way, "any leak is contained, it is easier to defend the site against terrorism, and land is used more efficiently".

Leak or no leak, I wonder if anyone living or working above the plant will feel safe. Instead, I would like to propose that a nuclear plant, if needed, should be built at sea, as a floating platform. After all, in the event of a dangerous situation, we should move the plant - not the people around the plant. There is only one way to do this: The plant has to be afloat at sea.

The advent of Small Modular Reactors (SMRs) provides a viable solution. SMRs are serially manufactured fission reactors with capacities ranging from about 50 to 500 megawatts. A number of countries, notably Russia and France, produce SMRs.

Each reactor module is transportable by sea. SMRs produce heat by fission of a nuclear material, emitting no gas. The heat may be used to produce steam to drive turbines or for desalination or other industrial processes.

The systems downstream of the heat source are the same as those found in any conventional steam-turbine power plant.

A floating SMR power plant (or fSMR) consists of a nuclear fission reactor below the water line. The boiler drum, turbine, condenser, alternator and transformers are, for ease of operation and maintenance, installed above the water line. An air-gap between both improves stability.

The suite of offshore oil rigs - semi-submersibles, jack-ups, tension leg platforms, spars and drill ships - provides many possible solutions to the hull form.

Circulating water for the condenser comes from the sea beneath, eliminating space for cooling towers. The footprint of each fSMR is less than 100m in any direction. Its design is not site-specific. It can be installed anywhere with sufficient water depth, regardless of the geology of the seabed. It is deployable, and is easily replaced with a new one when it gets old.

These floating plants do not require refuelling for months or even years. Refuelling is done at a dedicated place to which they may be towed. Maintenance and decommissioning are carried out at an accredited shipyard. A spare fSMR can stand in during the time it is taken out of commission.

BUILDING SUCH PLANTS IS DO-ABLE

Singapore is a world leader in offshore rig solutions. Although it would be a quantum leap, it is an incremental step to move from the construction of oil rigs to fSMRs.

We need only to develop the expertise to install and commission the nuclear reactor. The skill set for the rest of the system downstream of the reactor is not new.

The existing infrastructure - mooring specialists, heavy-lift cranes, classification societies and dry tow transporters - will support an fSMR construction industry. From being a world leader in offshore rigs, Singapore has what it takes to be a world leader in building fSMRs. However, its yards need a strategic partner that can deliver the SMR, with a good brand like France's Areva. A matchmaker is needed to bring the two parties together. The Economic Development Board can fulfil that role.

Can an fSMR be defended against terrorism? Sure.

The sea surrounding Singapore is among the safest in the world due to the high level of vigilance and port protocol. Nevertheless, a concrete floating barrier/breakwater of 200m in diameter should be built around the fSMR.

The mooring system for the barrier would be designed to allow the barrier to move a couple of metres. The compression of the fenders, the motion of the barrier and the friction of the water will absorb the kinetic energy of the impact when any collision occurs.

Radar, underwater ultrasonic, weapon-bearing drones and high- voltage fencing would provide additional surveillance and protection.

Can the fSMR's off-peak output be used? Of course.

I have encouraged the national water agency PUB to consider the use of floating, steel-framed reservoirs with fabric linings.

A desalination plant with a floating reservoir can be located close to an fSMR to tap energy during the night off-peak hours. This would smooth the load and optimise efficiency. The reservoir may be used to grow vegetables or rear fish.

Has it been done before? Yes. Since the first nuclear submarine USS Nautilus in 1954, many naval and icebreaking ships are nuclear-powered.

Shipyards in Russia and China are, or will be, increasingly used to build floating nuclear plants.

In the United States, even though wind, tidal current, solar and shale gas are abundant, fSMR interest is emerging. Professors at the Massachusetts Institute of Technology and University of Wisconsin have gone public with plans to design fSMRs, inspired by advances in offshore rig-building technology.

While the capital cost of an fSMR is high, the levelised cost is not prohibitive. This is a measure of the cost of producing renewable energy over its expected lifetime energy output. This unit cost is derived by dividing the lifecycle cost, including land, capital expenditure, construction, fuel, operation and maintenance on a present-value basis by all the energy produced over the life of the plant.

In Singapore, due to the very high cost of land, the difference between the levelised costs of an fSMR and a conventional gas-fired plant would be attractive.

To be sure, the notion of a floating nuclear plant in Singapore may seem startling to some. But my point is that this is a sensible solution that builds on Singapore's expertise in offshore rig building, and which can be cost-effective. It is no sci-fi solution, but a distinct possibility.

•The writer is managing director of Floating Solutions LLP.