(A breeder reactor is a reactor in which more fissile material can be harvested from spent nuclear fuel than present in the original fresh fuel elements. It can, however, be transformed in breeder reactors into fissile uranium-233 (U-233), just like non-fissile U-238 (99.3% of natural uranium) can be transformed in a breeder reactor to fissile plutonium. Thorium itself is not a fissile material. For that reason, we examine here the claims of thorium proponents.Ĭlaim 1: The use of thorium expands the availability of nuclear fuel by a factor 400 These claims should be submitted to a scientific fact check. Over the past decade, a group of globally active nuclear proponents is recommending thorium as fuel for a safe and affordable nuclear power technology without larger waste and proliferation problems. Distinctive is the highly penetrating gamma radiation from its decay-chain (thallium-208 (Tl-208): 2.6 MeV compared to gamma radiation from Cs-137: 0.66 MeV). There are currently hardly any technical applications.
It belongs to the group of actinides, is around 3 to 4 times more abundant than uranium and is radioactive (half-life of Th-232 as starter of the thorium decay-chain is 14 billion years with alpha-decay). Thorium (Th) is a heavy metal of atomic number 90 (uranium has 92). Thus development of a thorium fuel cycle without effective denaturation of bred fissile materials is irresponsible. A severe disadvantage is that uranium-233 bred from thorium can be used by terror organisations for the construction of simple but high-impact nuclear explosives. Concerning safety and waste disposal there are no convincing arguments in comparison to uranium fuel. It is 3 to 4 times more abundant than uranium. It can only be transformed into fissile uranium-233 using breeder and reprocessing technology. Thorium itself is, however, not a fissile material. This paper provides an historical background of MSR R&D efforts, surveys and summarizes many of the recent development, and provides analysis comparing thorium-based MSRs.Thorium is currently described by several nuclear proponents as a better alternative to uranium fuel. T MSRs has been selected as one of six most promising Generation IV systems and development activities have been seen in fast-spectrum MSRs, waste-burning MSRs, MSRs fueled with low-enriched uranium (LEU), as well as more traditional thorium fuel cycle-based MSRs. Subsequent design studies in the 1970s focusing on thermal-spectrum thorium-fueled systems established reference concepts for two major design variants: (1) a molten salt breeder reactor (MSBR), with multiple configurations that could breed additional fissile material or maintain self-sustaining operation and (2) a denatured molten salt reactor (DMSR) with enhanced proliferation-resistance. Early MSR work was supported by a significant research and development (R&D) program that resulted in two experimental systems operating at ORNL in the 1960s, the Aircraft Reactor Experiment and the Molten Salt Reactor Experiment. The MSR is most commonly associated with the U-233/thorium fuel cycle, as the nuclear properties of U-233 combined with the online removal of parasitic absorbers allow for the ability to design a thermal-spectrum breeder reactor however, MSR concepts have been developed using all neutron energy spectra (thermal, intermediate, fast, and mixed-spectrum zoned concepts) and with a variety of fuels including uranium, thorium, plutonium, and minor actinides. For liquid-fuelled MSRs, the salt can be processed online or in a batch mode to allow for removal of fission products as well as introduction of fissile fuel and fertile materials during reactor operation. Molten salt reactors (MSRs) represent a class of reactors that use liquid salt, usually fluoride- or chloride-based, as either a coolant with a solid fuel (such as fluoride salt-cooled high temperature reactors) or as a combined coolant and fuel with fuel dissolved in a carrier salt.
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