On a once through basis, ThorCon is not that uranium efficient. Over 8 years, we feed 2,185 kg of U-235 to a 250 MWe module. This equates to 208 tons of natural uranium per full power GW-y. For comparison a standard 1 GW Light Water Reactor (LWR) requires about 250 tons of natural uranium per year. However, at the end of 8 years, the module’s “spent” fuel will contain 1289 kgs of U-233 and U235. ThorCon’s net consumption of fissile is less than half that of a LWR, due to higher thermal efficiency, removal of Xe-135, and U-233 production from thorium. ThorCon “spent” fuel is about 9% U-235 and 4% U-233. This is highly enriched by normal standards. Re-enriching this back to 20% will take about 48 SWU per kg U-235. Currently, an SWU costs $90 and this is likely to drop in the future as the last of the diffusion plants are pushed out of the market. $4000 per kg of U-235 is extremely cheap. Such re-enrichment would cut ThorCon’s uranium requirements in half.
The World Nuclear Association reckons current uranium reserves are 5.9 million tons at $130 per kg uranium and 7.6 million tons at $260. If, for sake of argument, we assume 4 million tons were available to ThorCon and no re-enrichment, then we have 19,200 GW-y of uranium. If we start turning out 100 one GW ThorCons per year, then at year 19 we will have used up our 4 million tons. At this point, nearly 2000 one GW ThorCons will be producing about half the world’s electricity while generating no SO2, no NOx, no ash, and nil CO2. ThorCon will have been spectacularly successful.
This fleet will also be eating into the remaining reserves at the rate of 416,000 tons per year. Of course, this is 30 years from now. Some fairly simple improvements, for example re-enriching, will halve this burn rate. But even so, if reserves were static, we’d run out of uranium in another 20 years, about 50 years from now
But reserves will not be static. ThorCon will push up the real price of uranium and new reserves will be developed. Known low grade sources such as phosphate deposits, enrichment tailings, and coal ash will be exploited. In commodities, the rule of thumb is a doubling in real price increase reserves ten-fold. Miners don’t produce reserves until they have an economic motive to so. The US has been operating at an oil Reserves to Production ratio of less than 10 for at least 50 years. Uranium’s current 90:1 R/P is an anomaly. Most commodities operate at much lower Reserves to Production ratio, usually with no long-term increase in real price.
Advances in exploration and extraction technology always seem to outpace the predictions. For example, the sea contains about 4.6 billion tons of uranium. River flows add about 32,000 tons of uranium to the ocean each year. Solar powered evaporation then increases the concentration of uranium in sea-water. The uranium concentration is still a very low 3 ppb. But activated polymers are being developed which have a remarkable ability to pull uranium out of the water. Currently, Japanese and DOE researchers are claiming seawater extraction costs of about $600 per kilogram of uranium, about six times the current market price. If a number like this becomes reality, then ThorCon’s fuel cost on this uranium is 1.65 cents per kilowatt-hour.
The point here is that ThorCon can accept a six-fold increase in the real price of uranium, and still beat coal. One way or another, such a price increase will result in a massive increase in reserves. And that massive increase will carry us to 2100 by which time we can confidently expect order of magnitude improvements in our ability to extract nuclear power from uranium and thorium.
The problem is not what happens 50 to a 100 years from now. The problem is what happens in the next 20 years. That’s the problem that ThorCon focuses on.