Thorium Disadvantages

Uranium-233 is a fissile isotope of uranium that is bred from thorium-232 as part of the thorium fuel cycle. Uranium-233 was investigated for use in nuclear weapons. Uranium-233 is produced by the neutron irradiation of thorium-232. Thorium-232 absorbs a neutron, becomes thorium-233, then quickly decays into protactinium-233. Protactinium-233 has a half-life of 27 days and before decaying into uranium-233. This protactinium has a large cross-section and can absorb neutrons needed to sustain fission. Because uranium-233 releases so few neutrons in thermal-spectrum, and because 2 neutrons are needed to sustain a chain reaction, existence of protactinium would stop fission. Protactinium-233 is a challenge unique to thorium reactors. Low breeding ratio is a challenge unique to breeder reactors fueled by thorium, which operate in thermal-spectrum. The 5,000 tpy figure of Thorium assumes a 50,000 tpy Rare Earths facility that primarily utilizes monazite as its feed-stock. Thorium is a companion element to Monazite. Monazite runs at +50% REE and about 7% Th. So if you processed 50,000 tons of monazite you would get about 3,500 tpy of Th. However, monazite would not be the only feed-stock. You would use many other mineralizations. like apatite running at 3% REE and .002% Th (but with lots of heavy REE). So it would be a mix and tend toward the 5,000 tpy range. Thorium Disadvantages listed in this video: 00:00 Solid-fuel thorium reactors fuel utilization ratios similar to PWR. 00:42 Liquid-Fuel in United States licensing is "scary". 02:04 Obama Administration willing to give away MSR know-how. 02:40 PWR seen as "good enough" for long time. 03:00 Licensing restrictions specifically target liquid-fuel. 04:45 NEA OECD evaluated solid-fuel, and liquid-fuel-fast-spectrum only. 20:50 Thermal-spectrum neutrons hitting U233 produce only ~2.3 neutrons. 23:00 Graphite moderator required to sustain fission in MSBR thermal-spectrum. 27:50 Protactinium-233 half-life 27 days. 29:00 Material challenges (MSR is pre-requisite so MSR challenges are Th challenges.)