Sometime between 2020 and 2040, we will invent a practically unlimited energy source that will solve the global energy crisis. This unlimited source of energy will come from thorium. A summary of the benefits, from a recent announcement of the start of construction for a new prototype reactor:
- There is no danger of a melt-down like the Chernobyl reactor.
- It produces minimal radioactive waste.
- It can burn plutonium waste from traditional nuclear reactors.
- It is not suitable for the production of weapon grade materials.
- Global thorium reserves could cover our energy needs for thousands of years.
If nuclear reactors can be made safe and relatively cheap, how popular could they get?
It depends on how cheap we're talking about. Most reactor designs utilize thorium use molten salt (or lead) as a coolant. Even though they were developed as early as 1954, molten salt-coolant reactors are a relatively immature technology. Interestingly enough, the first nuclear reactor to provide usable amounts of electricity was a molten salt reactor. Three were built as part of the US Aircraft Reactor Experiment (ARE), whose purpose was to build a reactor small and sturdy enough to power a nuclear bomber. These reactors are about the size of a large truck.
State-of-the-art nuclear reactors, such as Westinghouse's AP1000, cost $1.5 billion to build and produce 1.1 gigawatts of electricity. They cost around $50 million per year to maintain, and $30 million per year for uranium fuel. Nevertheless, they are slowly starting to compete with other sources of power like solar and fossil fuels. Eventually, they will rocket right past them. The goal is plants that only cost only $990 per kilowatt. A kilowatt-year of electricity sells for about $876, and a gigawatt-year $876 million, so even if these plants cost $1 billion to build, they can make $964 million worth of electricity every year. If fuel and maintenance costs are about $225 million per year, then your profit is $739 million/year. This is a huge profit. What prevented us from reaping the benefits of this in the past was inferior and more expensive building techniques frequently running overbudget, with some projects costing $4 - $5 billion to complete.
The AP1000 is a Generation III reactor, a new class of reactor that started coming online in 1996. More advanced Generation III reactors are sometimes called Generation III+, because they offer better performance but are not revolutionary. The benefits of Generation III+ reactors are obvious. They are economically competitive, but still have high capital and fuel costs. A lot of this high capital cost comes from excessive safety regulations. In "The Nuclear Energy Option", Bernard L. Cohen calculates that ever-escalating safety restrictions increase the cost of nuclear power plants by as much as four or five times, compensating for inflation:
Commonwealth Edison, the utility serving the Chicago area, completed its Dresden nuclear plants in 1970-71 for $146/kW, its Quad Cities plants in 1973 for $164/kW, and its Zion plants in 1973-74 for $280/kW. But its LaSalle nuclear plants completed in 1982-84 cost $1,160/kW, and its Byron and Braidwood plants completed in 1985-87 cost $1880/kW -- a 13-fold increase over the 17-year period. Northeast Utilities completed its Millstone 1,2, and 3 nuclear plants, respectively, for $153/kW in 1971, $487/kW in 1975, and $3,326/kW in 1986, a 22-fold increase in 15 years. Duke Power, widely considered to be one of the most efficient utilities in the nation in handling nuclear technology, finished construction on its Oconee plants in 1973-74 for $181/kW, on its McGuire plants in 1981-84 for $848/kW, and on its Catauba plants in 1985-87 for $1,703/kW, a nearly 10-fold increase in 14 years. Philadelphia Electric Company completed its two Peach Bottom plants in 1974 at an average cost of $382 million, but the second of its two Limerick plants, completed in 1988, cost $2.9 billion -- 7.6 times as much. A long list of such price escalations could be quoted, and there are no exceptions. Clearly, something other than incompetence is involved.
That something is huge safety restrictions. When the risk of meltdown is removed, these restrictions will be lifted. Carlo Rubia, a Nobel Prize-winning physicist and advocate of thorium power, writes, "after a suitable "cool-down" period, radioactive "waste" reaches radio-toxicities which are comparable and smaller than the one of the ashes coming from coal burning for the same produced energy". So waste and containment - the two main sources of cost and controversy for traditional reactors -- are all but eliminated with thorium.
The world-changing thorium reactor I am envisioning qualifies as a Generation IV reactor. A Generation IV reactor will pay for itself even more quickly than a Generation III reactor, and will replace every other source of electrical power in terms of cost-effectiveness. Generation IV reactors will be the fission reactors to end all fission reactors.
The Generation IV International Forum's definition:
Generation IV nuclear energy systems are future, next-generation technologies that will compete in all markets with the most cost-effective technologies expected to be available over the next three decades.
Comparative advantages include reduced capital cost, enhanced nuclear safety, minimal generation of nuclear waste, and further reduction of the risk of weapons materials proliferation. Generation IV systems are intended to be responsive to the needs of a broad range of nations and users.
Currently, it is thought that Generation IV reactors will not come online before 2030, at least according to the Generation IV International Forum's Technology Roadmap. A substantial amount of R&D must be done to develop the molten salt reactor idea into a viable construction plan. However, I am more optimistic on timescales. Improvements in materials science and high-quality manufacturing will relax design requirements, decreasing research time from 20 years to 10 years and building time from 3-5 years to one year. That is why I can imagine thorium reactors by 2020.
Thorium reactors will be cheap. The primary cost in nuclear reactors traditionally is the huge safety requirements. Regarding meltdown in a thorium reactor, Rubbia writes, "Both the EA and MF can be effectively protected against military diversions and exhibit an extreme robustness against any conceivable accident, always with benign consequences. In particular the [beta]-decay heat is comparable in both cases and such that it can be passively dissipated in the environment, thus eliminating the risks of "melt-down". Thorium reactors can breed uranium-233, which can theoretically be used for nuclear weapons. However, denaturing thorium with its isotope, ionium, eliminates the proliferation threat.
Like any nuclear reactor, thorium reactors will be hot and radioactive, necessitating shielding. The amount of radioactivity scales with the size of the plant. It so happens that thorium itself is an excellent radiation shield, but lead and depleted uranium are also suitable. Smaller plants (100 megawatts), such as the Department of Energy's small, sealed, transportable, autonomous reactor (SSTAR) will be 15 meters tall, 3 meters wide and weigh 500 tonnes, using only a few cm of shielding. From the Lawrence Livermore National Laboratory page on SSTAR:
SSTAR is designed to be a self-contained reactor in a tamper-resistant container. The goal is to provide reliable and cost-effective electricity, heat, and freshwater. The design could also be adapted to produce hydrogen for use as an alternative fuel for passenger cars.
Most commercial nuclear reactors are large light-water reactors (LWRs) designed to generate 1,000 megawatts electric (MWe) or more. Significant capital investments are required to build these reactors and manage the nuclear fuel cycle. Many developing countries do not need such large increments of electricity. They also do not have the large-scale energy infrastructure required to install conventional nuclear power plants or personnel trained to operate them. These countries could benefit from smaller energy systems, such as SSTAR, that use automated controls, require less maintenance work, and provide reliable power for as long as 30 years before needing refueling or replacement.
SSTAR also offers potential cost reductions over conventional nuclear reactors. Using lead or leadâ€“bismuth as a cooling material instead of water eliminates the large, high-pressure vessels and piping needed to contain the reactor coolant. The low pressure of the lead coolant also allows for a more compact reactor because the steam generator can be incorporated into the reactor vessel. Plus with no refueling downtime and no spent fuel rods to be managed, the reactor can produce energy continuously and with fewer personnel.
Because thorium reactors present no proliferation risk, and because they solve the safety problems associated with earlier reactors, they will be able to use reasonable rather than obsessive standards for security and reliability. If we can reach the $145-in-1971-dollars/kW milestone experienced by Commonwealth Edison in 1971, we can decrease costs for a 1-gigawatt plant to at most $780 million, rather than the $1,100 million to build such a plant today. In fact, you might be able to go as low as $220 million or below, if 80% of reactor costs truly are attributable to expensive anti-meltdown measures. A thorium reactor does not, in fact, need a containment wall. Putting the reactor vessel in a standard industrial building is sufficient.
Current operating costs, ignoring fuel costs, for a 1-gigawatt plant are about $50 million/year. With greater automation and simplicity in Generation IV plants, in addition to more reasonable safety and security regulations, this cost will be decreased to $5 million/year, equivalent to the salary of about 60 technicians earning $80K/year. Because the molten salt continuously recirculates the fuel, the time-consuming replacement of fuel rods is not necessary - you just dump in the thorium and out comes energy. However, if molten salt is used as a coolant, it must be recirculated and purified external to the reactor vessel. This requires a chemical reprocessing facility, of a type that has only yet been demonstrated in a lab. The scale-up to industrial levels has currently been labeled as uneconomic, but improvements in salt purification technology over the next decade will bring the costs down greatly, and eventually the entire process will be automated. If thorium reactors become popular, automated, and mass-produced, the technology could improve to the point where the cost of maintaining a 1-gigawatt nuclear reactor will eventually drop as low as $1 million/year, or less.
Today, the nuclear industry primarily makes money by selling fuel to reactor operators. So there is little incentive to switch over to a fuel that will eventually be obtainable for as low as $10/kg. According to "The Economics of Nuclear Power", a kg of enriched uranium in the form of uranium oxide reactor fuel is $1633/kg.
Today, thorium is relatively expensive - about $5,000 per kilogram. However, this is only because of there is currently little demand for thorium, so as a specialty metal, it is expensive. But there is 4 times as much thorium in the earth's crust as there is uranium, and uranium is only $40/kg. If thorium starts to be mined en masse, its cost could drop to as low as $10/kg. This factor-of-500 reduction in cost would be similar to the reduction in cost that electricity experienced throughout this century, only compressed into a few years. It is estimated that Norway alone contains 180,000 tons of known thorium reserves. Global deposits of thorium:
- 360,000 India
- 300,000 Australia
- 170,000 Norway
- 160,000 United States
- 100,000 Canada
- 35,000 South Africa
- 16,000 Brazil
- 95,000 Others
Thorium could cost a lot less than uranium fuel because it doesn't need to be enriched to be used as fuel. As stated before, enriched uranium oxide gas costs $1633/kg, and 1-gigawatt nuclear power plants buy about $30 million in fuel annually, which works out to about 20,000 kg. You can read more at the wikipedia entry for the uranium market.
Even if the price of thorium never goes below $50/kg, it still represents a factor-of-32 economy improvement over uranium oxide. If a 1-gigawatt thorium reactor consumes amounts of thorium similar to the amount of uranium consumed by nuclear reactors today, fueling it for a year would only cost $1 milion, using the $50/kg price point, or $200,000, using the $10/kg price point.
Building a 1-gigawatt uranium plant today costs about $1.1 billion. Building a 1-gigawatt thorium plant will cost only about $250 million, or less, because meltdown concerns can be tossed out the window. This fundamentally changes the economics of nuclear power. We can call this the capital cost benefit of thorium.
Fueling a 1-gigawatt uranium plant today costs $30 million/year. Fueling a 1-gigawatt thorium plant will cost only $1 million/year, because thorium is four times more abundant than uranium and does not need to be enriched - only purified - prior to being used as fuel. We can call this the fuel cost benefit of thorium.
Staffing a 1-gigawatt uranium plant today costs $50 million/year. With greater automation, and (especially) fewer safety/security requirements, we will decrease that cost to $5 million/year. Instead of requiring 500 technicians, guards, personal assistants, janitors, and paper pushers to run a nuclear plant, we will only need a small group of 30 or so technicians to run the plant. (When the technology reaches maturity.) Generation IV nuclear plants will be designed to be low-maintenance.
Based on these numbers, over a 60-year operating lifetime, both plants produce 60 gigawatt-years of power. The total cost for the uranium plant is $4.9 billion, at a rate of $81.6 million per gigawatt-year. The total cost for the thorium plant is $490 million, at a rate of $8.16 million per gigawatt-year. Thorium power makes nuclear power ten times cheaper than it used to be, right off the bat.
Of course, ten times cheaper electricity is impressive, and blows everything else out of the water, but it doesn't quite qualify as the "unlimited source of energy" I was talking about. Why will thorium lead to practically unlimited energy?
Because thorium reactors will make nuclear reactors more decentralized. Because of no risk of proliferation or meltdown, thorium reactors can be made of almost any size. A 500 ton, 100MW SSTAR-sized thorium reactor could fit in a large industrial room, require little maintenance, and only cost $25 million. A hypothetical 5 ton, truck-sized 1 MW thorium reactor might run for only $250,000 but would generate enough electricity for 1,000 people for the duration of its operating lifetime, using only 20 kg of thorium fuel per year, running almost automatically, and requiring safety checks as infrequently as once a year. That would be as little as $200/year after capital costs are paid off, for a thousand-persons worth of electricity! An annual visit by a safety inspector might add another $200 to the bill. A town of 1,000 could pool $250K for the reactor at the cost of $250 each, then pay $400/year collectively, or $0.40/year each for fuel and maintenance. These reactors could be built by the thousands, further driving down manufacturing costs.
Smaller reactors make power generation convenient in two ways: decreasing staffing costs by dropping them close to zero, and eliminating the bulky infrastructure required for larger plants. For this reason, it may be more likely that we see the construction of a million $40,000, 100 kW plants than 400 $300 million, 1GW plants. 100 kW plants would require minimal shielding and could be installed in private homes without fear of radiation poisoning. These small plants could be shielded so well that the level of radiation outside the shield is barely greater than the ambient level of radiation from traces of uranium in the environment. The only operating costs would be periodic safety checks, flouride salts, and thorium fuel. For a $40,000 reactor, and $1,000/year in operating costs, you get enough electricity for 100 people, which is enough to accomplish all sorts of antics, like running thousands of desktop nanofactories non-stop.
Even smaller reactors might be built. The molten salt may have a temperature of around 1,400Â°F, but as long as it can be contained by the best alloys, it is not really a threat. The small gasoline explosions in your automobile today are of a similar temperature. In the future, personal vehicles may be powered by the slow burning of thorium, or at least, hydrogen produced by a thorium reactor. Project Pluto, a nuclear-powered ramjet missile, produced 513 megawatts of power for only $50 million. At that price ratio, a 10 kW reactor might cost $1,000 and provide enough electricity for 10 persons/year while consuming only 1 kg of thorium every 5 years, itself only weighing 1000kg - similar to the weight of a refrigerator. I'm not sure if miniaturization to that degree is possible, or if the scaling laws really hold. But it seems consistent with what I've heard about nuclear power in the past.
The primary limitation with nuclear reactors, as always, is containment of radiation. But alloys and materials are improving. We will be able to make reactor vessels which are crack-proof, water-proof, and tamper-proof, but we will have to use superior materials. We should have those materials by 2030 at the latest, and they will make possible the decentralized nuclear energy vision I have outlined here. I consider it probable unless thorium is quickly leapfrogged by fusion power.
The greatest cost for thorium reactors remains their initial construction. If these reactors can be made to last hundreds of years instead of just 60, the cost per kWh comes down even further. If we could do this, then even if there were a disaster that brought down the entire industrial infrastructure, we could use our existing reactors with thorium fuel for energy until civilization restarts. We could send starships to other solar systems, powered by just a few tons of thorium. We will simultaneously experience the abundance we always wanted from nuclear power with the decentralization we always wanted from solar power. We will build self-maintaining "eternal structures" that use thorium electricity to power maintenance robots capable of working for thousands of years without breaks.
What nuclear reactors provide:
- fresh water through desalination
Links to further material:
Molten salt reactor on Wikipedia
Aircraft Reactor Experiment (ARE) on Wikipedia
Nuclear aircraft on Wikipedia
Generation IV reactor on Wikipedia
Project Pluto on Wikipedia
More on Project Pluto
Energy from Thorium blog
Thorium support in Norway
Thorium Power, Inc.
Thorium chemical characteristics
The Nuclear Energy Option by Bernard L. Cohen
The Economics of Nuclear Power by the Uranium Information Centre Ltd.
A Pro-Nuclear website
Greenpeace founder recants about nuclear power
The Energy Amplifier by Nobelist Carlo Rubbia
Investment Stimulus for New Nuclear Power Plant Construction FAQ
World Nuclear Association
How To Build 6,000 Nuclear Plants by 2050
Trivia: The word thorium derives from the Scandanavian god of thunder, Thor. So it seems unsurprising that Norway is so supportive of thorium. I doubt the people that named thorium could have guessed the godlike energy it contains, but the name does seem apt in retrospect. Thorium oxide was originally used to make gas lanterns burn more brightly. Ralph Lucas, of the House of Lords, is also a thorium supporter.