Initial and makeup 233U fuel for a thorium molten salt reactor can be produced in a fusion breeder with 2.4% 232U that will make this fuel “self-protected” by its strong gamma radiation according to IAEA standards. 232U significantly contributes towards nonproliferation of nuclear weapons use. Fusion technology even early in its development towards a commercial power plant nevertheless can produce 233U by neutron capture in 232Th and simultaneously produce both 231Pa and 232U in a neutron reaction having a 6 MeV threshold making fusion’s 14 MeV neutrons uniquely well suited for this purpose. The 231Pa can make 232U by neutron capture in the fusion breeder in large enough quantity to make the simultaneously produced 233U self protected with 2.4% 232U. Excess 231Pa can be extracted and exported to fission reactors where by neutron capture 232U is made in situ for nonproliferation purposes. When the fission reactor’s conversion ratio of fertile to fissile approaches unity (breeding or isobreeding) its fissile 233U is produced internally with too little 232U nonproliferant made to satisfy the 2.4% rule because fission’s neutrons are below the 6 MeV threshold. In this case, as the conversion ratio approaches unity, 231Pa is supplied so that the production of 232U by neutron capture in 231Pa keeps 232U/233U=2.4%.
In the long term, producing 233U by fusion breeding avoids the need for isotope enrichment facilities to be greatly expanded thus contributing to nonproliferation. In the short term, before fusion bred 231Pa, 232U and 233U become available, the required fissile material can come from enriched 235U with enough 238U to be denatured for nonproliferation or can come from plutonium from spent fuel.
Isotope breeding can be a significant revenue stream for neutronic fusion systems compared to the revenue from electricity generation.
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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