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 reactorss 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 reactorss will make nuclear reactors more decentralized. Because of no risk of proliferation or meltdown, thorium reactorss 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 1,400°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 reactorss 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.
Source: A Nuclear Reactor in Every Home