Wednesday, 5 October 2016

A floating nuclear power plant - off Singapore?

The Republic could be a world leader in building small reactors deployed at sea, including in nearby waters
By Lim Soon Heng, Published The Straits Times, 4 Oct 2016

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.















Time for Singapore to say 'Yes' to nuclear
A floating nuclear power plant mitigates risks and offers economic advantages
By Lim Soon Heng, Published The Straits Times, 15 Mar 2017

The Fukushima nuclear accident dealt a blow to the emerging "nuclear renaissance" just when the world was close to putting Chernobyl behind it.

In its aftermath, several countries, including Japan and Germany, put aside, under public pressure, plans to build nuclear power plants (NPPs).

Six years after Fukushima, 61 new nuclear plants are under construction, in Britain, China, India, Russia and even the United States, where lobbyists from the oil and gas industry ply the corridors of power. France, undeterred, continues to keep its economy humming, with 77 per cent of its energy needs coming from nuclear fission. Scandinavian countries opt for nuclear rather than dam up their stunning fjords. Vietnam pushes ahead with its plan to build the first NPP in Asean.

But Singapore continues to vacillate, despite its strategic vulnerability, with its 95 per cent dependence on natural gas flowing from Indonesia and Malaysia for as long as goodwill on the other side prevails.

Natural gas is expensive and pollutive. Regular replenishment is needed or the economy halts. Gas-fired power plants require additional land for unloading terminals, tanks, regasification units, flue gas treatment plants and kilometres of pipelines. Carbon sequestration looms in the future.

Each year, 25 million gigawatt hours of electricity are generated worldwide. Studies by the University of Wisconsin-Madison conclude that 944.4 tonnes of CO2 (if coal-fired) and 564.3 tonnes (if gas-fired) are released for each gigawatt hour.

Singapore, on a per capita basis, is a significant polluter.

This is not to deny the risks from NPPs. One commonly cited risk is radioactive particle leaks, which is possible. But radioactivity is not as deadly as naysayers proclaim.

Without radioactive emissions, we would all be dead. The human body is radioactive and much of our food is naturally radioactive. Many medical procedures are radiation-dependent.

Exposure to radiation becomes hazardous when the subject receives more than 100,000 microsieverts a year for multiple years. To put this in perspective, the radiation recorded in Tokyo 10 days after the Fukushima accident was 0.125 microsievert an hour or 1,096 microsieverts a year. This level is below the threshold and safe.

The accidents at Three Mile Island, Chernobyl and Fukushima, tragic though they were, provided engineers with valuable lessons. The last link in the events leading to the meltdown of the reactors was the loss of cooling water needed to remove the decay heat after the shutdown of the reactor.

The reactor shutdown was accomplished in seconds. However, after the reactor is shut down, the nuclear fuel continues to produce heat, called decay heat.

Cooling water needs to be circulated to keep the temperature of the fuel under control.

In these three accidents, meltdown occurred because of the failure of the cooling water pump. The circulation of the cooling water failed owing to a complete loss of backup power to operate the associated pumps.

To address this, engineers have introduced a passive cooling system, which works by natural convection and will work even when the NPP suffers a total blackout.

And the extensive discharge of radioactive particles in Fukushima was caused by the explosion of hydrogen that resulted from the reaction between the molten uranium and the zirconium cladding of the fuel tubes.

Measures to prevent this are being devised.

It is reassuring that, after previously opposing it, Prime Minister Lee Hsien Loong has said that a nuclear plant is possible in his lifetime and that Singapore "cannot afford to dismiss it".

There are good reasons to seriously consider going nuclear. Natural gas supply can be threatened by political instability or blatant disregard by a party to an agreement to supply it. This would cause havoc to the economy.

With water, Singapore has developed fallbacks should its main supplier abrogate a deal. We should be as resilient with natural gas.

Five countries control 72 per cent of the world's proven reserves of 187,300 billion cubic m.

We must remind ourselves that in 1973, oil prices quadrupled, taking the world by surprise.

What about renewables? For Singapore, this can never meet our base load. And it is only a matter of time before fossil fuels run out.

The way I see it, there is only one option to future-proof our economy: Go nuclear.

This can be done with uranium fission for the immediate future, and possibly thorium or hydrogen fusion for our grandchildren's time.

With the economy trending towards more intensive digital number-crunching, our per capita electrical energy consumption of 8,500 kilowatt hours is likely to rise along with our population. We cannot resolve this conundrum without going nuclear.

NPPs have small footprints because nuclear fuel is 50 million times more energy-dense than gas.

A nuclear reactor does not require gas-fired plants' aforementioned paraphernalia to support it. Its capacity factor is, according to many studies, almost twice that of a gas-fired heat source. This means less downtime for maintenance.

Its lifespan is also longer. The higher capital cost of an NPP is more than offset by its longer life, low maintenance requirements, cheaper fuel and more productive use of land.

Studies have shown that the levelised cost of energy - a way of comparing energy options - is lower than that of fossil or renewable plants, if the cost of funds is less than 4 per cent.

Small modular reactors that can be replicated and scaled up can drive costs even lower.

As for spent fuel, a lifetime of spent fuel can be kept in a pool of a modest size. In fact, 78 per cent of the spent fuel accumulated over five decades from all the NPPs in the US remains in water-filled pools today.

While gas is transported in liquefied natural gas ships or sub-sea pipelines to our shore, uranium can be shipped in boxes at a fraction of the cost.

Hydrogen produced with NPPs could be used in hydrogen fuel cells to power cars cleanly and cheaply. Cheap energy lowers the cost of business and improves our global competitiveness.

One of the biggest obstacles is what to do with a distressed nuclear power plant. If we can move it out of harm's way, there is no need for large exclusion zones.

We can indeed do this, if our NPPs are on floating platforms. Former minister mentor Lee Kuan Yew stated in 2008, when contemplating the prospect of NPPs to serve Singapore's energy needs:"I was thinking at one time about a floating platform. Put a nuclear station there and, if it blows, then we move it a few kilometres away from us."

No one foresaw Singapore becoming a market leader in offshore oil and gas rigs when it delivered its first offshore oil rig. But that market is mature and competition from lower-cost economies is intense. Singapore shipyards are in dire need of innovating and reinventing.

I am convinced that floating assets unrelated to oil and gas are the new horizon and a new area to develop. In particular, floating nuclear power plants are a disruptive technology worthy of the challenge.

What Singapore needs next is the political will to say "Yes" to nuclear.

The writer is managing director of Floating Solutions LLP.


No comments:

Post a Comment