2012 is an historic year for nuclear power, with the first new reactors gaining U.S. government approval in almost 35 years. The U.S. Nuclear Regulatory Commission – NRC – has approved the first nuclear reactors to be built in the U.S. since 1978.
The NRC voted 4-1 in favour of Southern Company building two new nuclear reactors at an existing Georgia plant. NRC Chairman Gregory Jaczko voted against, expressing concern that the licence was being approved “as if Fukushima never happened”. The reactors are expected to cost $US14 billion/£8.8 billion and could begin operating as early as 2016. No reactors have been approved for construction since a year before the accident at Three Mile Island, a nuclear power plant in Pennsylvania, in 1979.
Some have seen the approval of the Southern Company’s two Westinghouse AP-1000 reactors – to be built in Georgia – as the start of a revival of nuclear power in the West, but this may be a false dawn because of the problems besetting conventional reactors.
Safety concerns around nuclear power have risen following a meltdown at Japan’s Fukushima power plant in March 2011 after an earthquake and tsunami cut the plant off from the power grid.
In the wake of the Japanese disaster the commission launched a review into whether existing and new US reactors could withstand natural disasters like earthquakes and floods. It may be that when a new boom in nuclear power comes, it won’t be led by giant gigawatt installations, but by batteries of small modular reactors – SMRs – with very different principles from reactors of past generations ::::
Commissioner Jaczko said he believes approving the reactors “requires some type of binding commitment” that safety enhancements planned from the review would be in place before the reactors opened.
The go-ahead for Southern Company of Atlanta to add two reactors to its existing pair at the Vogtle Plant in Waynesboro is considered to be a test of whether the industry can avoid costly delays that plagued previous reactors. The Obama administration has offered Southern and its partners $8.3bn in federal loan guarantees. The reactor design – approved separately in December 2011 – will be used by utility companies in Florida and South Carolina.
Globally, the equation is extremely complicated, there’s a growing demand for electricity that is cheap and reliable, there’s also an increasing need to find sources of energy that doesn’t rely on doing business with hostile or unstable nations. At the same time, concerns over global warming have resulted in many governments pledging reductions in the amount of carbon dioxide they generate, new, stricter environmental regulations threaten to close coal-powered plants across Europe and the United States. The hope was that massive investments in alternative technologies such as solar and wind power would make up for this cut in generating capacity, but the inefficiencies and intermittent nature of these technologies has made it clear that something with the capacity and reliability of coal and natural gas plants is needed.
In his 2010 TED talk – Innovating to Zero – Bill Gates voiced his concern at our inability to meet growing world energy demand while simultaneously limiting our effect on the environment. He observed that we badly need “miracles” in low and zero-emission power generation technology in order to stabilize the earth’s mean surface temperature over the next century. Such a technology, he insisted, must be deployable on an international scale and competitive in the existing market. In the quest to find such a miracle, some are betting on SMR technology.
The problem is that nuclear energy is the proverbial political pariah, the public simply doesn’t trust nuclear energy.
While a handful of possible miracles are in the works, ranging from smarter wind farms to large-scale solar plants to an array of innovative nuclear reactor designs, from an engineering perspective, the nuclear route seems the most likely to yield a game-changer soon. Most recently, in fact, the SMR design’s inherent scalability and supposed affordability have been hyped as an answer to Mr. Gates’ call. Yet, while industry, government, and public enthusiasm for the SMR is certainly welcome, many of the details which may prevent the design from delivering our miracle often go unaddressed. Rather than deeming the SMR a mirage or praising it as a miracle, a more comprehensive discussion on the topic is needed, one which identifies the technology’s unique position as a potentially breakthrough stepping stone toward solving our pressing energy demand and climate change problems.
Hundreds of nuclear reactors have been built around the world – list below – some countries, such as France generate almost all of their electricity from it. Nuclear power has faced continuing questions over cost, safety and waste disposal. 104 nuclear plants provide the United States with 20 percent of the nation’s power, but a building permit hadn’t been issued since 1978 with no new reactors coming on line since 1996 and after the uproar from the environmental movement after nuclear accidents at Three Mile Island, Chernobyl and Fukushima, it seemed unlikely that any more would ever be approved. This fierce public opposition to nuclear power has caused many governments to take an almost schizophrenic stance regarding the atom.
SMR design is not new, but its proposed applications as a central player in the energy industry are. Small reactors providing less than 300 megawatts gave birth to nuclear power generation more than a half-century ago. Over time, engineers sought to consolidate reactor capacity in order to take financial advantage of economies of scale, logistical advantage of centralized control mechanisms, and regulatory advantage of the reduced number of waste storage sites. But despite these advantages, the challenges facing nuclear power have not been overcome in the US. Now the small reactor, newly envisioned as one block in a modular set, advertises assembly line-like production to combat capital costs and licensing hoops; plug-and-play implementation to reduce construction time; and individualized operation capability to enable progressive up-rating and potential load-following.
The use of nuclear generated electricity has been a see-saw technology.
The use of nuclear generated electricity has been a see-saw technology, Germany for example, decided more than a decade ago to lessen it’s reliance on nuclear power in favor of alternative energy, the severe winter of 2011-12 got so cold that the Danube was freezing and Germany was forced to put some of it’s mothballed reactors back into service. The public opposition to nuclear power also means that many Western countries have a shortage of nuclear engineers because many see it as a dying industry not worth getting into. This is particularly acute in the United States and Britain, neither of which have retained the capacity for building the huge reactor vessels and must farm this out to overseas manufacturers and maintenance engineers.
Spiegel reported – June 2011 – that the German government had agreed to a roadmap for phasing out it’s nuclear power. All of the country’s 17 nuclear plants were to go offline by 2021, with a possible one-year extension for three reactors, should there be the risk of an electricity shortfall. It was facetiously dubbed “the phaseout of the phaseout of the phaseout.” After weeks of heated discussion, the German government seemed to have made it clear that it was serious with its U-turn on nuclear energy. During the marathon meeting, the governing coalition parties, Chancellor Angela Merkel’s center-right Christian Democratic Union, its Bavarian sister party the Christian Social Union and the business-friendly Free Democrats – thrashed out the details of the planned nuclear shutdown. The proposals effectively reversed the government’s own decision- made in 2010 – to extend the operating lives of Germany’s 17 nuclear power plants – which was itself a reversal of the decision made by former Chancellor Gerhard Schröder’s Social Democratic-Green administration to phase out nuclear power by around 2020.
In her blog post – http://nukepowertalk.blogspot.com.au/ – Dr. Gail Marcus, an independent consultant on nuclear power technology and policy, says “The advantages – of SMRs – may lie more in the savings in financing costs if the plants can be built faster than in differences in the actual capital cost. There is also the fact that the utility’s outlay per plant is smaller, so the utility is less likely to have to “bet the company” on the commitment to build.” Marcus says “While there are some small reactor proposals that rely on the technologies we know, and could conceivably be built soon, most of the design concepts are very different than existing reactors. Raising the possibility of many unknowns that could slow or derail progress. At a minimum, the time needed for their development and deployment is considerably greater. In addition, the more innovative small reactor designs will also raise new regulatory issues to be dealt with by the Nuclear Regulatory Commission, so licensing the first of these may not be a quick or easy process.”
Electricity was first generated via nuclear energy on December 20, 1951 in the high desert of Idaho. That original output was 45 kW. Since then, reactors have grown much larger, with electrical outputs of over 1,400 MW. 50 years on from that first generation, reactors with low electrical outputs are being introduced once again.
One way of getting around many of these problems is through the development of SMR. These reactors are capable of generating about 300 megawatts of power, which is enough to run around 45,000 homes. SMRs are quite different from the radio-thermal generators – RTG – used in spacecraft and remote lighthouses in Siberia. Nuclear reactors such as SMRs use controlled nuclear fission to generate power while RTGs use natural radioactive decay to power a relatively simple thermoelectric generator that can only produce, at most, about two kilowatts. In terms of power, RTGs are the equivalent of batteries while small nuclear reactors are only “small” when compared to conventional reactors. They are hardly the sort that you would keep in the garage. In reality, SMR power plants would cover the area of a small shopping mall. Still, such an installation is not very large as power plants go and a reactor that only produces 300 megawatts may not seem worth the investment, but the US Department of Energy is offering US$452 million in matching grants to develop SMRs and private investors like the Bill Gates Foundation and the company of Babcock and Wilcox are putting up money for their own modular reactor projects.
One reason for government and private industry to take an interest in SMRs is that they’ve been successfully employed for much longer than most people realize. In fact, hundreds have been steaming around the globe inside the hulls of nuclear submarines and other warships for sixty years. They’ve also been used in merchant ships, icebreakers and as research and medical isotope reactors at universities. There was even one installed in the Antarctic at McMurdo Station from 1962 to 1972.
SMRs have a number of advantages over conventional reactors. For one thing, SMRs are cheaper to construct and run. This makes them very attractive to poorer, energy-starved countries; small, growing communities that don’t require a full-scale plant; and remote locations such as mines or desalination plants. Part of the reason for this is simply that the reactors are smaller. Another is that, not needing to be custom designed in each case, the reactors can be standardized and some types built in factories that are able to employ economies of scale. The factory-built aspect is also important because a factory is more efficient than on-site construction by as much as eight to one in terms of building time. Factory construction also allows SMRs to be built, delivered to the site, and then returned to the factory for dismantling at the end of their service lives – eliminating a major problem with old conventional reactors, i.e. how to dispose of them.
SMRs also enjoy a good deal of design flexibility. Conventional reactors are usually cooled by water – a great deal of water – which means that the reactors need to be situated near rivers or coastlines. SMRs, on the other hand, can be cooled by air, gas, low-melting point metals or salt. This means that SMRs can be placed in remote, inland areas where it isn’t possible to site conventional reactors.
This cooling system is often passive. In other words, it relies more on the natural circulation of the cooling medium within the reactor’s containment flask than on pumps. This passive cooling is one of the ways that SMRs can improve safety. Because modular reactors are smaller than conventional ones, they contain less fuel. This means that there’s less of a mass to be affected if an accident occurs. If one does happen, there’s less radioactive material that can be released into the environment and makes it easier to design emergency systems. Since they are smaller and use less fuel, they are easier to cool effectively, which greatly reduces the likelihood of a catastrophic accident or meltdown in the first place.
This also means that accidents proceed much slower in modular reactors than in conventional ones. Where the latter need accident responses in a matter of hours or minutes, SMRs can be responded to in hours or days, which reduces the chances of an accident resulting in major damage to the reactor elements.
The SMR designs that reject water cooling in favor of gas, metal or salt have their own safety advantages. Unlike water-cooled reactors, these media operate at a lower pressure. One of the hazards of water cooling is that a cracked pipe or a damaged seal can blow radioactive gases out like anti-freeze out of an overheated car radiator. With low-pressure media, there’s less force to push gases out and there’s less stress placed on the containment vessel. It also eliminates one of the frightening episodes of the Fukushima accident where the water in the vessel broke down into hydrogen and oxygen and then exploded.
Another advantage of modular design is that some SMRs are small enough to be installed below ground. That is cheaper, faster to construct and less invasive than building a reinforced concrete containment dome. There is also the point that putting a reactor in the ground makes it less vulnerable to earthquakes. Underground installations make modular reactors easier to secure and install in a much smaller footprint. This makes SMRs particularly attractive to military customers who need to build power plants for bases quickly. Underground installation also enhances security with fewer sophisticated systems needed, which also helps bring down costs.
SMRs can help with proliferation, nuclear waste and fuel supply issues because, while some modular reactors are based on conventional pressurized water reactors and burn enhanced uranium, others use less conventional fuels. Some, for example, can generate power from what is now regarded as “waste”, burning depleted uranium and plutonium left over from conventional reactors. Depleted uranium is basically U-238 from which the fissible U-235 has been consumed. It’s also much more abundant in nature than U-235, which has the potential of providing the world with energy for thousands of years. Other reactor designs don’t even use uranium. Instead, they use thorium. This fuel is also incredibly abundant, is easy to process for use as fuel and has the added bonus of being utterly useless for making weapons, so it can provide power even to areas where security concerns have been raised.
But there’s still the sticking point that modular reactors are, by definition, small. That may be fine for a submarine or the South Pole, but what about places that need more? Is the alternative conventional nuclear plants? It turns out that the answer is no. Modular reactors don’t need to be used singly. They can be set up in batteries of five or six or even more, providing as much power as an area needs. And if one unit needs to be taken off line for repairs or even replacement, it needn’t interfere with the operation of the others.
Types of Modular Reactors
There are, in fact, many more than are presented here, but this should give a good cross section of what is in the pipeline.
A modular light-water reactor is basically a scaled-down version of a conventional reactor. Like conventional reactors, it uses water as a coolant and a neutron moderator (that is, the water slows down the neutrons produced by the nuclear fuel so that the uranium atoms have a better chance of absorbing them and inducing nuclear fission. The trick of fission is simply to have enough nuclear fuel in one place with a moderator so that the reaction becomes self-sustaining). Engineers already have decades of experience with light-water SMRs because these are the type used on submarines and icebreakers, so the technology is already advanced and has had lots of field testing under very hard conditions. Imagine a nuclear power plant that has to be able to operate safely as it’s being tossed about in the ocean while sealed inside a submarine hull and you can see the daunting challenges that have been overcome.
Small light-water reactors aren’t as efficient as their larger cousins, but they have a number of advantages. Steam is produced in a nuclear plant by passing a loop of cooling water from the reactor through the steam generator, which is a separate vessel filled with coiling pipes. The hot cooling water enters the generator and as it runs through the pipes a second coil filled with water is heated by the water from the reactor. This changes to steam, which turns the turbines that turns the dynamos. On a conventional reactor, most types have the steam generator outside the reactor vessel. With light-water SMRs, the steam generator can be placed inside the vessel. This not only makes the reactor more compact and self-contained, but it also makes it much safer. One common problem in reactors is radioactive water leaking as it travels from the reactor to the steam generator. With the steam generator inside the reactor vessel, it’s the much safer situation of only non-radioactive water/steam going into and out of the reactor vessel.
The Westinghouse SMR is a miniature version of their AP1000 reactor. But where the AP1000 produces 1,154 megawatts and requires a plant covering 50 acres (20 ha), the Westinghouse SMR needs only 15 (6 ha), puts out 225 megawatts and can be built in 18 months as opposed to several years. The reactor and containment vessel stand 89 feet (27 m) high and 32 feet (9.8 m) in diameter, which makes it compact enough to be factory-built and shipped by rail to the site. Its fuel is standard enriched uranium that needs servicing every two years, but the reactor’s passive cooling system relies on the natural circulation of water rather than pumps, which means that even in the event of a complete power loss, as Fukushima suffered, the Westinghouse SMR can go for up to a week without needing any operator intervention to prevent damage.
Backed by Babcock and Wilcox, mPower is based on US Navy reactor designs and produces 160 megawatts when the system’s condensers are cooled by water, but it can be air-cooled as well, though with a lower power output. Seventy-five feet (23 m) high and 14 feet (4.3 m) in diameter, mPower is designed to be factory built, rail-shipped and installed below ground. Like the Westinghouse SMR, the mPower uses a passive cooling system and the steam generator is integral with the reactor. Unlike the Westinghouse SMR, the mPower needs refueling only every four years and the process involves simply replacing the entire core, which is inserted like a cartridge. The reactor has a 60-year service life and is designed to store its spent fuel on site for the duration.
NuScale seems impractically small with its output of only 45 megawatts, but it’s intended to be installed twelve at a time to provide up to 540 megawatts. These are each placed in an underground pool of water and each unit is cooled by natural circulation. Because of this, there are no pumps and the only moving parts in the reactor are those used to operate the control rods. When it is time for refueling, the reactor is removed from its pool by an overhead crane and taken to another section of the facility.
High-temperature Gas Cooled Reactors
As the term implies, gas-cooled reactors use a gas instead of water as a reactor cooling medium. In modern reactors this gas is usually helium because it’s an inert element that doesn’t react with other materials, yet is an excellent coolant (just ask any mixed-gas deep sea diver and he’ll tell you why they have a heating tube in their suit while breathing helium). This is important because, not using water, the moderator for the nuclear reaction is a graphite core, which is flammable. These operate at relatively low pressures and high gas temperatures of up to 1,800 degrees F (1,000 degrees C) and the gas either drives the turbines directly or via a steam generator. This reactor type has safety advantages because the way the design makes the nuclear reaction self-regulating. As the reactor gets hotter, the reaction slows down and the reactor cools. It also lends itself to smaller scales to allow for factory building and underground installation.
Built by a partnership led by General Atomics, the GT-MHR reactor has a capacity of 285 megawatts and can also be used to produce 100,000 tons of hydrogen gas per year. It has the interesting distinction of being able to run on weapons-grade plutonium. The reason for this was that the GT-MHR was originally designed to help dispose of Soviet nuclear warheads after the end of the Cold War. It also serves to highlight the practical applications of the SMRs’ ability to burn alternative nuclear fuels.
Fast Neutron Reactors
In conventional reactors, neutrons are slowed down by a moderator such as water, carbon or helium so that the uranium atoms have a better chance of absorbing them and initiating fission. A fast neutron reactor manages the same fission reaction except it does so by reflecting fast-moving neutrons back into the uranium in large quantities and thereby increasing the odds of fission. This has the advantage of allowing reactors to be very simple in design (and hence smaller) and to use enriched fuels, thorium or even nuclear waste as fuel.
There are two types of fast neutron systems used in current SMR designs. The first are candle, breed-burn or traveling-wave reactors. The second, standing wave reactors.
The “candle” name for the first variety stems from the fact that that’s what the fuel resembles. Put simply, it’s a big slab of depleted uranium with a plug of enriched uranium stuck in one end. When the nuclear reaction starts, the enriched uranium “ignites” the slab by initiating a reaction that turns the U-238 into Pu-239, an isotope of plutonium that can fission and generate power. This reaction burns along the slab at roughly one centimeter per year, creating and burning plutonium as it goes. It’s a process that can take years, even decades, as the reactor burbles away at a temperature of about 1,000 degrees F (550 degrees C) while cooled by liquid sodium, lead or lead-bismuth alloy.
The other version is called a “standing wave,” and the principle is the same, except instead of a great slab, the reactor is made up of fuel rods of U-238 and the reaction is started in the center. As the reaction proceeds outwards, the spent rods are reshuffled by the operators until all the fuel is consumed. The upshot of this is that a traveling wave reactor uses it fuel more efficiently and can run for 60 years without refueling. Theoretically, it could go for 200 years.
With either type, they are also unusual in that they have no moderator, rely on passive cooling, can be built in factories and have no moving parts. They are as close to plug-and-play as nuclear reactors can get.
Hyperion is another very small modular reactor that produces only 25 megawatts, but what it lacks in power it makes up for in portability. The reactor vessel is only 8 feet (2.5 m) tall and 5 feet (1.5 m) in diameter, has no moving parts and can go for ten years without refueling. When refueling is needed, the reactor is returned to the factory and replaced rather in the manner of a gas bottle. This configuration not only makes it possible to build multi-reactor power plants, but the individual reactors can also be used for applications like providing heat to extract oil from shale beds, steam for industrial uses and running desalination plants.
Power Reactor Innovative Small Module (PRISM) is a GE-Hitachi design. It’s sodium cooled, installed underground and generates 311 megawatts with refueling every six years. Its ability to burn plutonium and depleted uranium makes it of great interest to the UK, which is negotiating to have two installed at the Sellafield nuclear facility where they would be used to burn nuclear waste stockpiles. This is more than just a waste disposal solution. It’s estimated that if this works, the waste could provide power to Britain for 500 years.
Molten Salt Reactors
In this type of SMR, the coolant and the fuel are one in the same. The coolant is a mixture of lithium and beryllium fluoride salts. In this is dissolved a fuel, which can be enriched uranium, thorium or U-233. This molten salt solution passes at relatively low pressure and a temperature of 1,300 degrees F (700 degrees C) through a graphite moderator core. As the fuel burns, the waste products are removed from the solution and fresh fuel is added.
Flibe (Fluoride salt of Lithium and Beryllium) is a sort of reactor in a box. The US military wants to develop small reactors that can be easily set up at remote bases. Toward this end, the Flibe is designed around a power plant that packs into a set of cargo containers. The idea is to stick the reactor in the ground, set up the generating machinery and cover the lot with a building. The last doesn’t need to be anything like the containment building of a conventional reactor because the reactor is not only passively heated, but also features a salt plug that needs to be actively cooled at all times. If the reactor suffers a breakdown and the reactor starts to overheat, the plug melts and the molten salt/fuel mixture pours out into a drain tank. Power output is rated at 20 to 50 megawatts and it uses U-233 and thorium for fuel. This not only eliminates proliferation issues (neither U-233 nor thorium is completely unsuitable for weapons), but it also opens up a cheap, easily obtained energy source.
As impressive as many of these reactors sound, most of them are still in one stage or another of development or approval. It is a long way from there to flipping a switch and watching the lights go on. Most of these designs have roots that go back over half a century.
In the 1950s, Admiral Hyman Rickover, the architect of the US nuclear fleet, pointed out that the small research reactors, the precursors of SMRs, had a lot of advantages. They were simple, small, cheap, lightweight, easy to build, very flexible in design and needed very little development. On the other hand, practical reactors must be built on schedule, need a huge amount of development spent on “apparently trivial matters”, are expensive, large, heavy and complicated. In other words, there’s a large gap between what is promised by a technology in the design phase and what it ends up as once it’s built.
So it is with the current stable of SMRs. Many hold great promise, but they have yet to prove themselves. Also, they raise many questions. Will an SMR need fewer people to run it? What are its safety parameters? Will they fulfill current regulations? Will the regulations need to be changed to suit the nature of SMRs? Will evacuation zones, insurance coverage or security standards need to be altered? What about regulations regarding earthquakes?
Indeed, it is in government regulations that the modular reactors face their greatest challenges. Whatever the facts about nuclear accidents from Windscale to Fukushima, a large fraction of the public, especially in the West, is very nervous about nuclear energy in any form. There are powerful lobbies opposed to any nuclear reactors operating and the regulations written up by governments reflect these circumstances. Much of the cost of building nuclear plants is due to meeting all regulations, providing safety and security systems, and just dealing with all the legal barriers and paperwork that can take years and millions of dollars to overcome. Modular reactors have the advantage of being built quickly and cheaply, which makes them less of a financial risk, and factory manufacturing means that a reactor intended for a plant that missed approval can be sold to another customer elsewhere. And some SMRs are similar enough to conventional reactors that they don’t face the burden of being a “new” technology under skeptical scrutiny. However, red tape is still a very real thing.
Only time will tell if the small reactor becomes a common sight on our power grids, if it falls by the wayside like other technological dreams, or if it falls victim to the bureaucrats’ rule book.
Economics of new nuclear power plants
The economics of new nuclear power plants is a controversial subject, since there are diverging views on this topic, and multi-billion dollar investments ride on the choice of an energy source. Nuclear power plants typically have high capital costs for building the plant, but low direct fuel costs (with much of the costs of fuel extraction, processing, use and long term storage externalized). Therefore, comparison with other power generation methods is strongly dependent on assumptions about construction timescales and capital financing for nuclear plants. Cost estimates also need to take into account plant decommissioning and nuclear waste storage costs. On the other hand measures to mitigate global warming, such as a carbon tax or carbon emissions trading, may favor the economics of nuclear power.
In recent years there has been a slowdown of electricity demand growth and financing has become more difficult, which has an impact on large projects such as nuclear reactors, with very large upfront costs and long project cycles which carry a large variety of risks. In Eastern Europe, a number of long-established projects are struggling to find finance, notably Belene in Bulgaria and the additional reactors at Cernavoda in Romania, and some potential backers have pulled out. Where cheap gas is available and its future supply relatively secure, this also poses a major problem for nuclear projects.
Analysis of the economics of nuclear power must take into account who bears the risks of future uncertainties. To date all operating nuclear power plants were developed by state-owned or regulated utility monopolies where many of the risks associated with construction costs, operating performance, fuel price, and other factors were borne by consumers rather than suppliers. Many countries have now liberalized the electricity market where these risks, and the risk of cheaper competitors emerging before capital costs are recovered, are borne by plant suppliers and operators rather than consumers, which leads to a significantly different evaluation of the economics of new nuclear power plants.
Following the 2011 Fukushima Daiichi nuclear disaster, costs are likely to go up for currently operating and new nuclear power plants, due to increased requirements for on-site spent fuel management and elevated design basis threats
One of the big problems with nuclear power is the enormous upfront cost. These reactors are extremely expensive to build. While the returns may be very great, they’re also very slow. It can sometimes take decades to recoup initial costs. Since many investors have a short attention span, they don’t like to wait that long for their investment to pay off.
Because of the large capital costs for nuclear power, and the relatively long construction period before revenue is returned, servicing the capital costs of a nuclear power plant is the most important factor determining the economic competitiveness of nuclear energy. The investment can contribute about 70% to 80% of the costs of electricity. The discount rate chosen to cost a nuclear power plant’s capital over its lifetime is arguably the most sensitive parameter to overall costs.
The recent liberalization of the electricity market in many countries has made the economics of nuclear power generation less attractive. Previously a monopolistic provider could guarantee output requirements decades into the future. Private generating companies now have to accept shorter output contracts and the risks of future lower-cost competition, so they desire a shorter return on investment period. This favours generation plant types with lower capital costs even if associated fuel costs are higher.A further difficulty is that due to the large sunk costs but unpredictable future income from the liberalized electricity market, private capital is unlikely to be available on favourable terms, which is particularly significant for nuclear as it is capital-intensive.Industry consensus is that a 5% discount rate is appropriate for plants operating in a regulated utility environment where revenues are guaranteed by captive markets, and 10% discount rate is appropriate for a competitive deregulated or merchant plant environment; however the independent MIT study (2003) which used a more sophisticated finance model distinguishing equity and debt capital had a higher 11.5% average discount rate.
Another consideration is that even though consumer demand is not guaranteed, nuclear is placed among the lowest operating cost options. Once the plant is built, it has a distinct advantage over coal, gas, and other fuel based generation types in winning the momentary supply auctions, thereby resulting in operations at full reactor capacity. In this regard, typical present value (PV) calculations for risk-adjusted discount should be applied carefully, possibly approaching the guaranteed, captive market levels.
Currently the smallest nuclear power plant that can be built is usually larger than other power plants, making it possible for a utility to build the other plants in smaller increments, or in areas of low power consumption.
As states are declining to finance nuclear power plants, the sector is now much more reliant on the commercial banking sector. According to research done by Dutch banking research group Profundo, commissioned by BankTrack, in 2008 private banks almost invested 100’s of billions of dollars in the nuclear sector. Champions were BNP Paribas, with more than € 13,5 billion in nuclear investments and Citigroup and Barclays on par with billions of dollars in investments. Profundo added up investments in eighty companies in over 800 financial relationships with 124 banks in the following sectors: construction, electricity, mining, the nuclear fuel cycle and “other”.
Recent construction cost estimates
2007 estimates have considerable uncertainty in overnight cost, and vary widely from $US2,950/kWe (overnight cost) to a Moody’s Investors Service conservative estimate of between $US5,000 and $US6,000/kWe However, commodity prices shot up in 2008, and so all types of plants will be more expensive than previously calculated. In June 2008 Moody’s estimated that the cost of installing new nuclear capacity in the U.S. might possibly exceed $US7,000/kWe in final cost.
The reported prices at six new pressurized water reactors are indicative of costs for that type of plant:
- February 2008 – For two new AP1000 reactors at its Turkey Point site, Florida Power & Light calculated overnight capital cost from $2444 to $3582 per kW, which were grossed up to include cooling towers, site works, land costs, transmission costs and risk management for total costs of $3108 to $4540 per kilowatt. Adding in finance charges increased the overall figures to $5780 to $8071 per kW.
- March 2008 – For two new AP1000 reactors in Florida, Progress Energy announced that if built within 18 months of each other, the cost for the first would be $5144 per kilowatt and the second $US3376/kW – total $US9.4 billion. Including land, plant components, cooling towers, financing costs, license application, regulatory fees, initial fuel for two units, owner’s costs, insurance, taxes, escalation, and contingencies, the total would be about $US14 billion.
- May 2008 – For two new AP1000 reactors at the Virgil C. Summer Nuclear Generating Station in South Carolina, South Carolina Electric and Gas Co. and Santee Cooper expected to pay $9.8 billion (which includes forecast inflation and owners’ costs for site preparation, contingencies, and project financing).
- November 2008 – For two new AP1000 reactors at its Lee site, Duke Energy Carolinas raised the cost estimate to $11 billion, excluding finance and inflation, but apparently including other owners costs.
- November 2008 – For two new AP1000 reactors at its Bellefonte site, TVA updated its estimates for overnight capital cost estimates ranged to $US2516 to $US4649/kW for a combined construction cost of $US5.6 to 10.4 billion (total costs of $US9.9 to $US17.5 billion).
- April 2008 – Georgia Power Company reached a contract agreement for two AP1000 reactors to be built at Vogtle, at an estimated final cost of $US14 billion plus $US3 billion for necessary transmission upgrades.
In comparison, the AP1000 units already under construction in China have been reported with substantially lower costs due to significantly lower labour rates:
- In 2007, the reported cost for the first two AP1000 units under construction in China was $US5.3 billion.
- In 2009, the published cost for 4 AP1000 reactors under construction in China was a total of $US8 billion.
- in 2010, the Chinese nuclear commission expect construction costs would fall significantly once full scale mass production is underway. In addition, a domestic CAP1400 design based on the AP1000 is due to start construction in April 2013 with a scheduled start of 2017. Once the CAP1400 design has been proven, work is scheduled for a CAP1700 design with a target construction cost of $1000/kW
Construction delays can add significantly to the cost of a plant. Because a power plant does not earn income during construction, longer construction times translate directly into higher finance charges. Modern nuclear power plants are planned for construction in four years or less (42 months for CANDU ACR-1000, 60 months from order to operation for an AP1000, 48 months from first concrete to operation for an EPR and 45 months for an ESBWR) as opposed to over a decade for some previous plants. However, despite Japanese success with ABWRs, two of the four EPRs under construction (in Finland and France) are significantly behind schedule.
In some countries (notably the U.S.), in the past unexpected changes in licensing, inspection and certification of nuclear power plants added delays and increased construction costs. However, the regulatory processes for siting, licensing, and constructing have been standardized, streamlining the construction of newer and safer designs.
In the U.S. many new regulations were put in place in the years before and again immediately after the Three Mile Island accident’s partial meltdown, resulting in plant startup delays of many years. The NRC has new regulations in place now (see Combined Construction and Operating License), and the next plants will have NRC Final Design Approval before the customer buys them, and a Combined Construction and Operating License will be issued before construction starts, guaranteeing that if the plant is built as designed then it will be allowed to operate — thus avoiding lengthy hearings after completion.
In Japan and France, construction costs and delays are significantly diminished because of streamlined government licensing and certification procedures. In France, one model of reactor was type-certified, using a safety engineering process similar to the process used to certify aircraft models for safety. That is, rather than licensing individual reactors, the regulatory agency certified a particular design and its construction process to produce safe reactors. U.S. law permits type-licensing of reactors, a process which is being used on the AP1000 and the ESBWR.
In Canada, cost overruns for the Darlington Nuclear Generating Station, largely due to delays and policy changes, are often cited by opponents of new reactors. Construction started in 1981 at an estimated cost of $US7.4 Billion 1993-adjusted CAD, and finished in 1993 at a cost of $US14.5 billion. 70% of the price increase was due to interest charges incurred due to delays imposed to postpone units 3 and 4, 46% inflation over a 4 year period and other changes in financial policy. No new nuclear reactor has since been built in Canada, although a few have been and are undergoing refurbishment.
New nuclear power plants are not cheap. In the UK and the US cost overruns on nuclear plants contributed to the bankruptcies of several utility companies. In the US these losses helped usher in energy deregulation in the mid-1990s that saw rising electricity rates and power blackouts in California. When the UK began privatizing utilities, its nuclear reactors “were so unprofitable they could not be sold.” Eventually in 1996, the government gave them away. But the company that took them over, British Energy, had to be bailed out in 2004 to the extent of 3.4 billion pounds.
In general, coal and nuclear plants have the same types of operating costs (operations and maintenance plus fuel costs). However, nuclear has lower fuel costs but higher operating and maintenance costs.
Unlike other power plants, nuclear plants must be carefully guarded against both attempted sabotage (generally with the goal considered to be causing a radiological accident, rather than just preventing the plant from operating) and possible theft of nuclear material. Thus security costs of both protecting the physical plant and the screening of workers must be considered. Some other forms of energy also require high security, like natural gas storage facilities and oil refineries.
Since nuclear reactors contain a core of highly radioactive fuel, and around that core a complex cooling system which is also significantly contaminated, nuclear power plant operators need to invest considerable resources in keeping these structures intact, functioning, and isolated from the environment. Whereas a conventional power plant can break down without large environmental effects, this has to be prevented at a nuclear power plant at all cost. Also, society at present doesn’t perceive industrial risk as it used to in the early days of nuclear energy; it is now expected from nuclear plant operators that they will operate their plant with the highest safety standards, choosing the safest design, etc. In almost all cases that is precisely the most costly maintenance strategy and design.
Nuclear plants require fissionable fuel. Generally, the fuel used is uranium, although other materials may be used. In 2005, prices on the world market averaged $US20/lb ($US44.09/kg). On 2007-04-19, prices reached US$113/lb ($US249.12/kg). On 2008-07-02, the price had dropped to $US59/lb.
While the amounts of uranium used are a tiny fraction of the amounts of coal or oil used in conventional power plants, fuel costs account for about 28% of a nuclear plant’s operating expenses. Other recent sources cite lower fuel costs, such as 16%.Doubling the price of uranium would add only 7% to the cost of electricity produced.
Currently[when?], there are proposals to increase the numbers of nuclear power plants by 57% more reactors from the 435 currently in operation, according to John S. Herold’s Ruppel. While it is unlikely all proposed plants will actually be completed, an increase in plants, combined with the current decline in supply, caused by flooding at some of the world’s largest uranium mines, and speculators winning repositories in North America and Europe, means that prices are likely to increase. In addition, about 45% of the 2006 world supply of uranium came from old nuclear warheads, mostly Russian. At current supply and demand levels, those old stockpiles will be completely depleted by 2015. However, this assumes that the Integral Fast Reactor design, indeed all fast breeder reactors, will not be used.
Mining activity is growing rapidly, especially from smaller companies, but developing a uranium mine takes a long time, 10 years or more. The world’s present measured resources of uranium, economically recoverable at a price of 130 USD/kg according to the industry groups Organisation for Economic Co-operation and Development (OECD), Nuclear Energy Agency (NEA) and International Atomic Energy Agency (IAEA), are enough to last for “at least a century” at current consumption rates.
In 2011, Benjamin K. Sovacool said that even on optimistic assumptions of fuel availability, global reserves of uranium will only support a 2% growth in nuclear power and will only be available for 70 years. He said that uranium prices, like those of oil and natural gas, are highly volatile:
This means that uncertain uranium prices can have a grave impact on plant operating costs. Such price movement is hard to anticipate when, some of the countries now responsible for more than 30% of the world’s uranium production: Kazakhstan, Namibia, Niger, and Uzbekistan, are politically unstable.
All nuclear plants produce radioactive waste. To pay for the cost of storing, transporting and disposing these wastes in a permanent location, in the United States a surcharge of a tenth of a cent per kilowatt-hour is added to electricity bills. Roughly one percent of electrical utility bills in provinces using nuclear power are diverted to fund nuclear waste disposal in Canada.
In 2009, the Obama administration announced that the Yucca Mountain nuclear waste repository would no longer be considered the answer for U.S. civilian nuclear waste. Currently, there is no plan for disposing of the waste and plants will be required to keep the waste on the plant premises indefinitely.
The disposal of low level waste reportedly costs around £2,000/m³ in the UK. High level waste costs somewhere between £67,000/m³ and £201,000/m³. General division is 80%/20% of low level/high level waste, and one reactor produces roughly 12 m³ of high level waste annually.
In Canada, the Nuclear Waste Management Organization – NWMO – was created in 2002 to oversee long term disposal of nuclear waste, and in 2007 adopted the Adapted Phased Management procedure. Long term management is subject to change based on technology and public opinion, but currently largely follows the recommendations for a centralized repository as first extensively outlined in by AECL in 1988. It was determined after extensive review that following these recommendations would safely isolate the waste from the biosphere. The location has not yet been determined, as is expected to cost between $9 and $13 billion CAD for construction and operation for 60–90 years, employing roughly a thousand people for the duration. Funding is available and has been collected since 1978 under the Canadian Nuclear Fuel Waste Management Program. Very long term monitoring requires less staff since high-level waste is less toxic than naturally occurring uranium ore deposits within a few centuries.
At the end of a nuclear plant’s lifetime (estimated at between 40 and 60 years), the plant must be decommissioned. This entails either dismantling, safe storage or entombment. Operators are usually required to build up a fund to cover these costs while the plant is operating, to limit the financial risk from operator bankruptcy.
In the United States, the Nuclear Regulatory Commission (NRC) requires plants to finish the process within 60 years of closing. Since it may cost $300 million or more to shut down and decommission a plant, the NRC requires plant owners to set aside money when the plant is still operating to pay for the future shutdown costs. In June 2009, the NRC published concerns that owners were not setting aside sufficient funds.
A 2011 report for the Union of Concerned Scientists stated that “the costs of preventing nuclear proliferation and terrorism should be recognized as negative externalities of civilian nuclear power, thoroughly evaluated, and integrated into economic assessments—just as global warming emissions are increasingly identified as a cost in the economics of coal-fired electricity”.
The Union of Concerned Scientists have stated that “reactor owners … have never been economically responsible for the full costs and risks of their operations. Instead, the public faces the prospect of severe losses in the event of any number of potential adverse scenarios, while private investors reap the rewards if nuclear plants are economically successful. For all practical purposes, nuclear power’s economic gains are privatized, while its risks are socialized”.
Any effort to construct a new nuclear facility around the world, whether an existing design or an experimental future design, must deal with NIMBY or NIABY objections. Because of the high profiles of the Three Mile Island accident and Chernobyl disaster, relatively few municipalities welcome a new nuclear reactor, processing plant, transportation route, or nuclear burial ground within their borders, and some have issued local ordinances prohibiting the locating of such facilities there.
Nancy Folbre, an economics professor at the University of Massachusetts, has questioned the economic viability of nuclear power following the 2011 Japanese nuclear accidents:
The proven dangers of nuclear power amplify the economic risks of expanding reliance on it. Indeed, the stronger regulation and improved safety features for nuclear reactors called for in the wake of the Japanese disaster will almost certainly require costly provisions that may price it out of the market.
The cascade of problems at Fukushima, from one reactor to another, and from reactors to fuel storage pools, will affect the design, layout and ultimately the cost of future nuclear plants.
Globally nuclear liability risks resulting accidents are largely covered by the state, with only a small part of the risk carried by the private insurance industry. Worst case nuclear incident costs are so large that it would be difficult for the private insurance industry to carry the size of the risk, and the premium cost of full insurance would make nuclear energy uneconomic.
In Canada, the Canadian Nuclear Liability Act requires nuclear power plant operators to provide $75 million of liability insurance coverage. Claims beyond $75 million would be assessed by a government appointed but independent tribunal, and paid by the federal government.
In the UK, the Nuclear Installations Act of 1965 governs liability for nuclear damage for which a UK nuclear licensee is responsible. The limit for the operator is £140 million.
Insurance for nuclear or radiological incidents in the U.S. is organized by the Price-Anderson Nuclear Industries Indemnity Act. In general, nuclear power plants have private insurance and assessments that are pooled into a fund currently worth about $10 billion. Insurance claims beyond the fund’s size would be organized by, and probably paid by, the U.S. government. In July 2005, Congress extended this Act to newer facilities. For full history, details and controversy, see Price-Anderson Nuclear Industries Indemnity Act.
The Vienna Convention on Civil Liability for Nuclear Damage and the Paris Convention on Third Party Liability in the Field of Nuclear Energy put in place two similar international frameworks for nuclear liability. The limits for the conventions vary. The Vienna convention was adapted in 2004 to increase the operator liability to €700 million per incident, but this modification is not yet ratified.
Cost per kW·h
The cost per unit of electricity produced (kW·h) will vary according to country, depending on costs in the area, the regulatory regime and consequent financial and other risks, and the availability and cost of finance. Costs will also depend on geographic factors such as availability of cooling water, earthquake likelihood, and availability of suitable power grid connections. So it is not possible to accurately estimate costs on a global basis.
Various groups have attempted to estimate the economic cost for electricity generated by the most modern designs proposed for particular countries where these factors are generally fairly consistent.
In 2003, the Massachusetts Institute of Technology (MIT) issued a report entitled, “The Future of Nuclear Power”. They estimated that new nuclear power in the US would cost 6.7 cents per kW·h. However, the Energy Policy Act of 2005 includes a tax credit that should reduce that cost slightly.
The lifetime cost of new generating capacity in the United States was estimated in 2006 by the U.S. government (the 2007 report did not estimate costs). Nuclear power was estimated at 5.93 cents per kW·h. However, the “total overnight cost” for new nuclear was assumed to be $US1,984 per kWe – as seen above in Capital Costs, this figure is subject to debate.
A 2008 study based on historical outcomes in the U.S. said costs for nuclear power can be expected to run $US0.25-.30 per kW·h.
A 2008 study concluded that if carbon capture and storage was required then nuclear power would be the cheapest source of electricity even at $4,038/kW in overnight capital cost.
In 2009, MIT updated its 2003 study, concluding that inflation and rising construction costs had increased the overnight cost of nuclear power plants to about $4,000/kWe, and thus increased the power cost to US8.4¢/kW·h.
According to Benjamin K. Sovacool, the marginal levelized cost for “a 1,000-MWe facility built in 2009 would be 41.2 to 80.3 cents/kWh, presuming one actually takes into account construction, operation and fuel, reprocessing, waste storage, and decommissioning”.
Comparisons with other power sources
Generally, a nuclear power plant is significantly more expensive to build than an equivalent coal-fueled or gas-fueled plant. However, coal is significantly more expensive than nuclear fuel, and natural gas significantly more expensive than coal — thus, capital costs aside, natural gas-generated power is the most expensive. Most forms of electricity generation produce some form of negative externality — costs imposed on third parties that are not directly paid by the producer — such as pollution which negatively affects the health of those near and downwind of the power plant, and generation costs often do not reflect these external costs.
A comparison of the “real” cost of various energy sources is complicated by several uncertainties:
- The cost of climate change through emissions of greenhouse gases is hard to estimate. Carbon taxes may be enacted, or carbon capture and storage may become mandatory.
- The cost of environmental damage caused by (fossil or renewable) energy sources, both through land use (whether for mining fuels or for power generation) and through air and water pollution and solid waste.
- The cost and political feasibility of disposal of the waste from reprocessed spent nuclear fuel is still not fully resolved. In the U.S., the ultimate disposal costs of spent nuclear fuel are assumed by the U.S. government after producers pay a fixed surcharge.
- Operating reserve requirements are different for different generation methods. When nuclear units shut down unexpectedly they tend to do so independently, so the “hot spinning reserve” must be at least the size of the largest unit (this partly makes nuclear power more suitable for large grids). On the other hand, many renewables are intermittent power sources and may shut down together if they depend on weather conditions, so the grid will require either back-up generation capability or large-scale storage if the portion of generation from these renewables is significant. (Some renewables such as hydroelectricity have a storage reservoir and can be used as reliable back-up power for other power sources.)
- Governmental instabilities in the next plant lifetime. New nuclear power plants are designed for a minimum of 60 years (50 for VVER-1200), and may be able to be refurbished. Likewise, the waste from reprocessed fuel remains dangerous for about this period.
- Actual plant lifetime (to date, no plant has been shut down due to maximum licensed lifetime being reached, or been refurbished).
- Due to the dominant role of initial construction cost and the multi-year construction time and planned lifetime, the interest rate for the capital required is of particularly high importance for estimating the total cost.
Several recent comparisons of the costs of plants are available (see below); however, commodity prices have shot up since they were completed, and so all types of plants will be more expensive than shown
A UK Royal Academy of Engineering report in 2004 looked at electricity generation costs from new plants in the UK. In particular it aimed to develop “a robust approach to compare directly the costs of intermittent generation with more dependable sources of generation”. This meant adding the cost of standby capacity for wind, as well as carbon values up to £30 (€45.44) per tonne CO2 for coal and gas. Wind power was calculated to be more than twice as expensive as nuclear power. Without a carbon tax, the cost of production through coal, nuclear and gas ranged £0.022–0.026/kW·h and coal gasification was £0.032/kW·h. When carbon tax was added (up to £0.025) coal came close to onshore wind (including back-up power) at £0.054/kW·h — offshore wind is £0.072/kW·h — nuclear power remained at £0.023/kW·h either way, as it produces negligible amounts of CO2. (Nuclear figures included estimated decommissioning costs.)
However a much more detailed review of over 200 papers by the UK Energy Research Centre, on the issue of intermittency came to much lower costs about the cost of wind energy compared to nuclear energy. A recent study shows the current generating costs of wind, nuclear and coal plant in the UK which stills shows nuclear the cheapest, but not by a great a margin.
The lifetime cost of new generating capacity in the United States was estimated in 2006 by the U.S. government: wind cost was estimated at $55.80 per MW·h, coal (cheap in the U.S.) at $53.10, natural gas at $52.50 and nuclear at $59.30. However, the “total overnight cost” for new nuclear was assumed to be $1,984 per kWe – as seen above in Capital Costs, this figure is subject to debate, as much higher cost was found for recent projects. Also, carbon taxes and backup power costs were not considered.
A May 2008 study by the Congressional Budget Office concludes that a carbon tax of $45 per tonne of carbon dioxide would probably make nuclear power cost competitive against conventional fossil fuel for electricity generation.
The effect of subsidies is difficult to gauge, as some are indirect (such as research and development). A May 12, 2008 editorial in the Wall Street Journal stated, “For electricity generation, the EIA(Energy Information Administration, an office of the Department of Energy) concludes that solar energy is subsidized to the tune of $24.34 per megawatt hour, wind $23.37 and ‘clean coal’ $29.81. By contrast, normal coal receives 44 cents, natural gas a mere quarter, hydroelectric about 67 cents and nuclear power $1.59.”
However, the most important subsidies to the nuclear industry do not involve cash payments. Rather, they shift construction costs and operating risks from investors to taxpayers and ratepayers, burdening them with an array of risks including cost overruns, defaults to accidents, and nuclear waste management. This approach has remained remarkably consistent throughout the nuclear industry’s history, and distorts market choices that would otherwise favor less risky energy investments.
In 2011, Benjamin K. Sovacool said that: “When the full nuclear fuel cycle is considered – not only reactors but also uranium mines and mills, enrichment facilities, spent fuel repositories, and decommissioning sites – nuclear power proves to be one of the costliest sources of energy”.
Other Economic Issues
Ethicist Kristin Shrader-Frechette analysed 30 papers on the economics of nuclear power for possible conflicts of interest. She found of the 30, 18 had been funded either by the nuclear industry or pro-nuclear governments and were pro-nuclear, 11 were funded by universitys or non-profit non-government organisations and were anti-nuclear, the remaining 1 had unknown sponsors and took the pro-nuclear stance. The pro-nuclear studies were accused of using cost-trimming methods such as ignoring government subsides and using industry projections above empirical evidence where ever possible. The situation was compared to medical research were 98% of industry sponsored studies return positive results
Nuclear Power plants tend to be very competitive in areas where other fuel resources are not readily available — France, most notably, has almost no native supplies of fossil fuels. Frances nuclear power experience has also been one of paradoxically increasing rather than decreasing costs over time.
Making a massive investment of capital in a project with long-term recovery might impact a company’s credit rating.
A Council on Foreign Relations report on nuclear energy argues that a rapid expansion of nuclear power may create shortages in building materials such as reactor-quality concrete and steel, skilled workers and engineers, and safety controls by skilled inspectors. This would drive up current prices. It may be easier to rapidly expand, for example, the number of coal power plants, without this having a large effect on current prices.
Load following capability
Some existing LWR type plants have limited ability to significantly vary their output to match changing demand (called load-following). Other PWRs, as well as CANDU, BWR have load-following capability, which will allow them to fill more than baseline generation needs.
Some newer reactors also offer some form of enhanced load-following capability. For example, the Areva EPR can slew its electrical output power between 990 and 1,650 MW at 82.5 MW per minute. The number of companies that manufacture certain parts for nuclear reactors is limited, particularly the large forgings used for reactor vessels and steam systems. Only four companies (Japan Steel Works, China First Heavy Industries, Russia’s OMX Izhora and Korea’s Doosan Heavy Industries) currently manufacture pressure vessels for reactors of 1100 MWe or larger. Some have suggested that this poses a bottleneck that could hamper expansion of nuclear power internationally, however, some Western reactor designs require no steel pressure vessel such as CANDU derived reactors which rely on individual pressurized fuel channels. The large forgings for steam generators — although still very heavy — can be produced by a far larger number of suppliers.
Nuclear plants require 20–83 percent more cooling water than other power stations. During times of abnormally high seasonal temperatures or drought it may be necessary for reactors drawing from small bodies of water to reduce power or shut down. Nuclear plants situated on large lakes, seas or oceans are not affected by seasonal temperature variations due to the thermal stability of large bodies of water.
New Plants Under Construction
The latest plant designs currently available for building are generally called generation III+ reactors. They include AREVA’s European Pressurized Reactor (EPR), General Electric’s ESBWR, Westinghouse’s AP1000, and AECL’s ACR-1000. Russia, China, Japan, Korea and India all also have indigenous plant designs currently available for deployment.
In July 2008, Russia announced plans to allocate $40 billion from the state budget over the next 7 years for development of the nuclear energy sector and the nuclear industry. This will allow for construction of 26 major generating units in Russia by 2020 — about as many as were built in the entire Soviet period.
As of 2008, the UK has indicated that it will take steps to encourage private operators to build new nuclear power plants in the coming years to meet projected energy needs as fossil fuel prices climb, however there would be no subsidies from the UK government for nuclear power. An online calculator outlining UK means and limitations in meeting future energy needs illustrates the problem facing lawmakers and the public.
As of 2011, the People’s Republic of China has 13 nuclear power reactors spread out over 4 separate sites (Daya Bay, Qinshan, Tianwan, and Ling Ao), and 27 under construction. China’s National Development and Reform Commission has indicated the intention to raise the percentage of China’s electricity produced by nuclear power from the current 1% to 6% by 2020 (compared to 20% in the USA as of 2008). This will require the current installed capacity of 10.2 GW to be increased to 70–80 GW (more than France at 63 GW). However, rapid nuclear expansion may lead to a shortfall of fuel, equipment, qualified plant workers and safety inspectors.
The 1600 MWe EPR reactor is being built in Olkiluoto Nuclear Power Plant, Finland. A joint effort of French AREVA and German Siemens AG, it will be the largest pressurized water reactor (PWR) in the world. The Olkiluoto project has been claimed to have benefited from various forms of government support and subsidies, including liability limitations, preferential financing rates, and export credit agency subsidies, but the European Commission’s investigation didn’t find anything illegal in the proceedings. However, as of August 2009, the project is “more than three years behind schedule and at least 55% over budget, reaching a total cost estimate of €5 billion ($7 billion) or close to €3,100 ($4,400) per kilowatt”. Finnish electricity consumers interest group ElFi OY evaluated in 2007 the impact of Olkiluoto-3 to be slightly over 6%, or 3€/MWh, to the average market price of electricity within Nord Pool Spot. The delay is therefore costing the Nordic countries over 1.3 billion euros per year as the reactor would replace more expensive methods of production and lower the price of electricity.
Four ABWRs are already in operation in Japan, and one more is being built in Japan and two in Taiwan. South Korea plans to build 12 new nuclear reactors by 2022.
Russia has begun building the world’s first floating nuclear power plant. The £100 million vessel, the Akademik Lomonosov, is the first of seven plants (70 MWe per ship) that Moscow says will bring vital energy resources to remote Russian regions.
In December 2009 the United Arab Emirates declined both the American and French bids and awarded a contract for construction for four APR-1400s to a South Korean group including Korea Electric Power Corporation, Hyundai Engineering and Construction,Samsung and Doosan Heavy Industries.
Following the Fukushima nuclear disaster in 2011, costs are likely to go up for currently operating and new nuclear power plants, due to increased requirements for on-site spent fuel management and elevated design basis threats. After Fukushima, theInternational Energy Agency halved its estimate of additional nuclear generating capacity built by 2035.
Many license applications filed with the U.S. Nuclear Regulatory Commission for proposed new reactors have been suspended or cancelled. As of October 2011, plans for about 30 new reactors in the United States have been “whittled down to just four, despite the promise of large subsidies and President Barack Obama’s support of nuclear power, which he reaffirmed after Fukushima”. The only reactor currently under construction in America, at Watts Bar, Tennessee, was begun in 1973 and may be completed in 2012. Matthew Wald from the New York Times has reported that “the nuclear renaissance is looking small and slow”.
Small modular reactors (SMRs) are part of a new generation of nuclear power plants being designed all over the world. The objective of these SMRs is to provide a flexible, cost-effective energy alternative. Small reactors are defined by the International Atomic Energy Agency as those with an electricity output of less than 300 MWe, although general opinion is that anything with an output of less than 500 MWe counts as a small reactor. Modular reactors are manufactured at a plant and brought to the site fully constructed. They allow for less on-site construction, increased containment efficiency, and heightened nuclear materials security.
Electricity was first generated from nuclear energy on December 20, 1951 in the high desert of south-eastern Idaho. The original electrical output was estimated at 45 kW. Since then, reactors have grown much larger, with electrical outputs of over 1,400 MW. Almost 50 years after the first nuclear energy was generated, applications for reactors with low electrical outputs are being introduced again.
According to a report prepared by Oak Ridge National Laboratory, the long-term goal of nuclear power is to “develop an economic, safe, environmentally acceptable, unlimited supply of energy for society.”
Remote locations often have difficulty finding economically efficient, reliable energy sources. Small nuclear reactors have been considered as solutions to many energy problems in these hard-to-reach places.
Many of these smaller reactor designs are being made “modular” – in other words, they will be manufactured and assembled at a central factory location. They are then sent to their new location where they can be installed with very little difficulty. These SMRs are particularly useful in remote locations where there is usually a deficiency of trained workers and a higher cost of shipping. Containment is more efficient, and proliferation concerns are lessened. SMRs are also more flexible in that they do not necessarily need to be hooked in to a large power grid, and can generally be attached to other modules to provide increased power supplies if necessary.
There may be some economic benefits to SMRs as well. While the small power output of an SMR means that electricity will cost more per MW than it would from a larger reactor, the initial cost of building the plant is much less than that of constructing a much more complex, non-modular, large nuclear plant. It makes an SMR a smaller-risk venture for power companies than other nuclear power plants.
There are a variety of different types of SMR. Some are simplified versions of current reactors, others involve entirely new technologies.
Fission and reactivity control
Nuclear power plants generate heat through nuclear fission. When an unstable nucleus (such as 235U) absorbs an extra neutron, the atom will split, releasing large quantities of energy in the form of heat and radiation. The split atom will also release neutrons, which can then be absorbed by other unstable nuclei, causing a chain reaction. A sustained fission chain is necessary to generate nuclear power.
A nuclear fission chain is required to generate nuclear power.
There are certain conditions that must be met for this chain reaction to occur. Certain fuel densities are necessary, or the neutrons won’t impact new atoms. It is also easier for unstable nuclei to absorb neutrons when the neutrons are travelling at a certain speed. For 235U, slower neutrons are more likely to cause a fission reaction. In order to slow down the neutrons in a reactor core, a moderator is used. Water is the most common moderator in use today. The neutrons are slowed down as they travel through the water. As the reaction speeds up and the temperature of the reactor increases, increasing the temperature of the moderator, the neutrons aren’t slowed down as effectively. This in turn reduces the rate of nuclear reactions inside the core, since the faster neutrons aren’t as easy to absorb. This effect, the negative temperature coefficient, makes the reactor inherently resistant to “excursion”, or a sudden, uncontrolled increase in temperature.
Many SMRs are “fast reactors” – they don’t use moderators to slow down the neutrons. The fuel requirements in this kind of reactor are a little different. The atoms have to absorb neutrons travelling at higher speeds. This usually means changing the fuel arrangement within the core, or using different fuel types. 239Pu is more likely to absorb a high-speed neutron than 235U would be. However, the same negative temperature coefficient comes into play with fast nuclear reactors. Once the core heats up too much and the neutrons start to move faster, even the elements that would usually be able to absorb neutrons have trouble capturing them. Fission slows, and the reactor cannot run out of control.
Another benefit of these fast reactors is that some of them are breeder reactors. As these reactors produce energy, they also let off enough neutrons to transmute non-fissionable elements into fissionable ones. A very common use for a breeder reactor is to surround the core in a “blanket” of 238U, which is the most easily found isotope of uranium. Once the 238U undergoes a neutron absorption reaction, it becomes 239Pu, which can be removed from the reactor once it is time to refuel, and used as more fuel once it has been cleaned.
Currently, most reactors use water as a coolant. Light water (H2O) is more common than heavy water (D2O). New reactor designs are experimenting with different coolant types. Liquid metal reactors have been used both in the U.S. and other countries for some time. Gas-cooled reactors and Molten salt reactors are also being looked at as an option for very high temperature operation.
Traditionally, nuclear reactors use a coolant loop to heat water into steam, and use that steam to run turbines to generate electricity. There are some of the new gas-cooled reactor designs that are meant to drive a gas-powered turbine, rather than using a secondary water system. Also, there are some plants now that are used for their ability to generate thermal, rather than electric, energy. Nuclear reactor heat can be used inhydrogen production and myriad commercial operations. Right now some of the possible nuclear heat applications include water desalination, heat for the production of petroleum products (extracting oil from tar sands, creating synthetic oil from coal, etc.), and the production of hydrogen for use in anything from car batteries to nitrogen fertilizers.
The electricity needs in remote locations are usually small and highly variable. Large nuclear power plants are generally rather inflexible in their power generation capabilities. SMRs have to have a load-following design so that when electricity demands are low they will produce a lower amount of electricity.
Many SMRs are designed to use new fuel ideas that allow for higher burnup rates and longer lifecycles. Longer refueling intervals can decrease proliferation risks and lower chances of radiation escaping containment. For reactors in remote areas, accessibility can be troublesome, so longer fuel life can be very helpful.
Because of the lack of trained personnel available in remote areas, SMRs have to be inherently safe. Many larger plants have active safety features that require “intelligent input,” or human controls. Many of these SMRs are being made using passive safety features and inherent safety features. Passive safety features are engineered, but do not require outside input to work. A pressure release valve may have a spring that can be pushed back when the pressure gets too high. Inherent safety features require no engineered, moveable parts to work. They only depend on physical laws.
Since there are several different ideas for SMR’s, there are many different safety features that can be involved. Coolant systems can use natural circulation – convection – so there are no pumps, no moving parts that could break down, and they keep removing decay heat after the reactor shuts down, so that the core doesn’t overheat and melt. Negative temperature coefficients in the moderators and the fuels keep the fission reactions under control, causing the fission reactions to slow down as temperature increases.
Several SMR developers are claiming that their designs will require fewer staff members to run the reactors because of the increased inherent and passive safety systems. Some of the reactors, like the Toshiba 4S, are reportedly designed to run with little supervision.
Many SMRs are fast reactors that are designed to have higher fuel burnup rates. The higher temperature a reactor can run at, the more fission products it can usually burn, reducing the amount of waste produced in nuclear power plants. As mentioned before, some SMRs are also breeder reactors, which not only “burn” fuels like 235U, but will also convert fissionable materials like 238U (which occurs naturally at a much higher concentration than 235U) into usable fuels.
Some reactors are designed to run on alternative thorium fuel cycle, which offers significantly reduced long-term waste radiotoxicity compared to uranium cycle.
There has been some interest in the concept of a traveling wave reactor, a new type of breeder reactor that uses the fuel it breeds. The idea would eliminate the need to remove the spent fuel and “clean” it before reusing any newly bred fuel.
The use of nuclear materials to create weapons is always a concern. Many SMRs are designed to lessen the danger of materials being stolen or misplaced. Nuclear reactor fuel is low-enriched uranium, or has a concentration of less than 20% 235U. This low quantity, non-weapons-grade uranium makes the fuel less desirable for weapons production. Once the fuel has been irradiated, the fission products mixed with the fissile materials are highly radioactive and require special handling to remove safely, another non-proliferation feature.
Reactors designed to run on alternative thorium fuel cycle offer increased proliferation resistance compared to conventional uranium cycle.
The modular construction of SMRs is another useful feature. Because the reactor core is often constructed completely inside a central manufacturing facility, fewer people have access to the fuel before and after irradiation.
There are numerous new reactor designs being generated all over the world. A small selection of the current SMR designs is listed below.
Westinghouse Electric’s small modular 225 MW version of the AP1000 PWR will be built underground in a hole that measures about 100 feet deep and 100 feet wide. All of the components are housed in the 90-foot tall reactor vessel not visible to the casual observer. An AP1000 facility needs about 50 acres; the SMR needs 15. The entire construction process is expected to take about 18 months, compared to several years needed for the AP1000. Westinghouse expects the first SMR to generate electricity by 2020.
Developed by the Argentinean National Atomic Energy Commission (CNEA) & INVAP, CAREM is a simplified pressurized water reactor (PWR) designed to have electrical output of 100MW or 25MW. It is an integral reactor – the coolant system is inside the reactor vessel – so that the entire plant operates at the same pressure.
The fuel is uranium oxide with a U enrichment of 3.4%. The primary coolant system uses natural circulation, so there are no pumps required, which provides inherent safety against core meltdown, even in accident situations. The integral design also minimizes the risk of loss-of-coolant accidents (LOCA). Annual refueling is required.
Encapsulated Nuclear Heat Source (ENHS): United States
ENHS is a liquid metal reactor (LMR) that uses lead (Pb) or lead-bismuth (Pb-Bi) coolant. Pb has a higher boiling point than the other commonly used coolant metal, sodium, and is chemically inert with air and water. The difficulty is finding structural materials that will be compatible with the Pb or Pb-Bi coolant, especially at high temperatures. The ENHS uses natural circulation for the coolant and the turbine steam, eliminating the need for pumps. It is also designed with autonomous control, with a load-following power generation design, and a thermal-to-electrical efficiency of more than 42%. The fuel is either U-Zr or U-Pu-Zr, and can keep the reactor at full power for 15 years before needing to be refueled, with either239Pu at 11% or 235U at 13%
It requires on-site storage, at least until it cools enough that the coolant solidifies, making it very resistant to proliferation. However, the reactor vessel weighs 300 tons with the coolant inside, and that can pose some transportation difficulties.
Modified KLT-40: Russia
Based on the design of nuclear power supplies for Russian icebreakers, the modified KLT-40 uses a proven, commercially available PWR system. It is intended to be portable. The coolant system relies on forced circulation of pressurized water during regular operation, although natural convection is usable in emergencies. The fuel may be enriched to above 20%, the limit for low-enriched uranium , which may pose non-proliferation problems. The reactor has an active (requires action) safety system with an emergency feedwater system. Refueling is required every two to three years.
International Reactor Innovative & Secure (IRIS): United States
Developed by an international consortium led by Westinghouse and the nuclear energy research initiative (NERI), IRIS-50 is a modular PWR with a generation capacity of 50MWe. It uses natural circulation for the coolant. The fuel is a uranium oxide with 5% enrichment of 235U that can run for five years between refueling. Higher enrichment might lengthen the refueling period, but could pose some licensing problems. Iris is an integral reactor, with a high-pressure containment design.
Purdue Novel Modular Reactor (PNMR): United States
Based on the boiling water reactor (BWR) designs by General Electric (GE), the PNMR is a small, 200 MWe or 50 MWe variation from Purdue University. The coolant steam drives the turbines directly, eliminating the need for a steam generator. It uses natural circulation, so there are no coolant pumps. The reactor has both negative void and negative temperature coefficients . It uses a uranium oxide fuel with 235U enrichment of 5%, which doesn’t need to be refueled for 10 years. The safety systems include gravity-driven water injection, in case of reactor core depressurization. The PNMR would require temporary on-site storage of spent fuel, and even with the modular design would need significant assembly.
Remote Site-Modular Helium Reactor (RS-MHR): United States
The RS-MHR is a General Atomics project. It is a helium gas cooled reactor. The reactor is contained in one vessel, with all of the coolant and heat transfer equipment enclosed in a second vessel, attached to the reactor by a single coaxial line for coolant flow. The plant is a four-story, entirely above-ground building with a 10–25 MW electrical output. The helium coolant doesn’t interact with the structural metals or the reaction, and simply removes the heat, even at extremely high temperatures, which allow around 50% efficiency, whereas water-cooled and fossil fuel plants average 30–35%. The fuel is a uranium oxide coated particle fuel with 19.9% enrichment. The particles are pressed into cylindrical fuel elements and inserted into graphite blocks. For a 10MWe plant, there are 57 of these graphite blocks in the reactor. The refueling period is six to eight years. Temporary on-site storage of spent fuel is required. Proliferation risks are fairly low, since there are few graphite blocks and it would be very noticeable if some went missing.
Super Safe, Small & Simple (4S): Japan
Designed by the Central Research Institute of Electric Power Industry (CRIEPI), the 4S is an extremely modular design, fabricated in a factory and requiring very little construction on-site. It is a sodium (Na) cooled reactor, using a U-Zr or U-Pu-Zr fuel. The design relies on a moveable neutron reflector to maintain a steady state power level for anywhere from 10 to 30 years. The liquid metal coolant allows the use of electro-magnetic (EM) pumps, with natural circulation used in emergencies.
NuScale: United States
Originally a Department of Energy and Oregon State University project, the NuScale module reactors have been taken over by NuScale Power, Inc. The NuScale is a light water reactor (LWR), with 235U fuel enrichment of less than 4.95%. It has a 2 year refueling period. The modules, however, are exceptionally heavy, each weighing approximately 500 tons. Each module has an electrical output of 45 MW, and a single NuScale power plant can be scaled from one to 24 modules. The company hopes to have a plant up and running by 2018, after they have received a license from the Nuclear Regulatory Commission.
Hyperion Power Module (HPM): United States
A commercial version of a Los Alamos National Laboratory project, the HPM is a LMR that uses a Pb-Bi coolant. It has an output of 25 MWe, and less than 20% 235U enrichment. The reactor is a sealed vessel, which is brought to the site intact and removed intact for refueling at the factory, reducing proliferation dangers. Each module weighs less than 50 tons. It has both active and passive safety features.
Pebble Bed Modular Reactor (PBMR): South Africa
The PBMR is a modernized version of a design first proposed in the 1950s and deployed in the 1960s in Germany. It uses spherical fuel elements coated with graphite and silicon carbide filled with up to 10,000TRISO particles, which contain uranium dioxide (UO2) and appropriate passivation and safety layers. The pebbles are then placed into a reactor core, composing around 450,000 “pebbles”. The core’s output is 165 MWe. It runs at very high temperatures (900°C) and uses helium, a noble gas as the primary coolant; helium is used as it does not interact with structural or nuclear materials. Heat can be transferred to steam generators or gas turbines, which can either use either Rankine (steam) or Brayton (gas turbine) cycles. South Africa terminated funding for the development of the PBMR in 2010; most scientists working on the project have moved abroad to nations such as the United States, Australia, and Canada.
Traveling Wave Reactor (TWR): United States
The TWR from Intellectual Ventures’ TerraPower team is another innovative reactor design. It is based on the idea of a fission chain reaction moving through a core in a “wave.” The idea is that the slow breeding and burning of fuel would move through the core for 50 to 100 years without needing to be stopped, so long as plenty of fertile 238U is supplied. The only enriched 235U required would be a thin layer to start the chain reaction. So far, the reactor only exists in theory, the only testing done with computer simulations. A large reactor concept has been designed, but the small modular design is still being conceptualized.
mPower: United States
The mPower from Babcock & Wilcox (B&W) is an integrated SMR. The nuclear steam supply systems (NSSS) for the reactor arrive at the site already assembled, and so require very little construction. Each reactor module would produce around 125MWe, and could be linked together to form the equivalent of one large nuclear power plant. B&W has submitted a letter of intent for design approval to the NRC.
Flibe Energy: United States
Flibe Energy is a US based company that intends to design, construct and operate small modular reactors based on liquid fluoride thorium reactor (LFTR) technology (a type of molten salt reactor). The name “Flibe” comes from FLiBe, a Fluoride salt of Lithiumand Beryllium, used in LFTRs. Initially 20-50 MW (electric) version will be developed, to be followed by 100 MWe “utility-class reactors” at a later time. Assembly line construction producing “mobile units that can be dispersed throughout the country where they need to go to generate the power.” is planned.