KitemanSA wrote:Great minds... ?Axil wrote: IMO, the one advantage that a molten salt /Polywell fusor has over a standard Liquid salt fluoride reactor (Lftr) is that the excess neutrons from the fusion process mitigates the need to reprocess the core salt to sustain fission. That makes the sealed Lftr operationally simple and enables it to operate for 50 years without manipulation of the core salt(Nasty soup ).
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The primary problem with thorium based molten salt reactor is the need to reprocess, which has the first step of chemically removing the bred U233 which is the actual fuel (thorium being fertile but not fissile). U233 is a potential bomb making material too; and being able to CHEMICALLY seperate it is SCARY! Therefore, to be safer, there should be no reprocessing. However, without reprocessing, there needs to be an external source of neutrons to overcome the poisoning of the protactinium (the intermediary between Th233 and U233).
One configuration of the Lftr is a core surrounded by a thorium blanket. There are two types of reprocessing of molten salt involved here; core salt and blanket salt.
Reprocessing of the core salt is not a proliferation threat because there are so many nuclear denaturant isotopes included in the core salt. Such reprocessing removes solid nuclear poisons to aid in maintaining criticality.
Because the blanket salt is relatively pure of nuclear denaturant isotopes, blanket salt reprocessing may be subverted to isolate U233.
The reason for blanket salt reprocessing is to support the maintenance of criticality, but the blanket is not absolutely required based on design.
The neutrons provided by a fusor will remove the need to remove solid poisons from the core salt to maintain criticality; core salt reprocessing is problematic in a third world country without a nuclear infrastructure.
The need for a blanket is also removed. Such a reactor configuration can only support proliferation using isotopic separation, a technology that is very hard to achieve without detection; (E.g. Iran).
I am interested in efficient, safe and simple third world nuclear power to replace coal use.
Further reading
http://www.nti.org/e_research/cnwm/over ... nical2.asp
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Notwithstanding these apparent attractions, no country has yet produced U-233 for nuclear weapons as far as is publicly known. Neither has U-233 been produced in significant quantities in civilian nuclear-energy operations (although its use as the fissile component in a "thorium fuel cycle" has been much analyzed and discussed). There are two main reasons that the U-233 option has not been exercised so far:
• First, it's much easier to produce plutonium-239 than U-233 in reactors fueled by natural uranium, which are the kinds of reactors with which countries seeking weapons tend to start. If a country seeking weapons has the capacity to make enriched uranium (which is needed to fuel the type of reactor best suited for making U-233), that country's easiest route to bombs is to use that capacity instead to enrich natural uranium to weapon-grade in U-235.
• Second, U-233 is invariably accompanied by at least a small admixture of U-232, whose radioactive-decay chain contains a powerful emitter of a very penetrating gamma ray (thallium-208). Even at an initial U-232 concentration as low as 1 part per million, the gamma dose-rate after two years of build-up of its decay chain is twice as great as the gamma dose-rate from correspondingly aged reactor-grade plutonium.[20] This would pose significant problems in the form of radiation exposure to workers in a weapon program (or a nuclear-power program) using U-233, and it would also make weapons containing U-233 quite difficult to conceal.
These reasons continue to make U-233 production an unlikely path for new proliferators to try to take to a bomb, and the fact that no significant stocks of this material appear to exist anywhere in the world mean it is also not a theft risk.