The Shanghai Institute of Applied Physics of the Chinese Academy of Sciences announced that the Chinese experimental TMSR-LF1 thorium-powered molten salt reactor in Wuwei, Gansu Province, has achieved the first successful conversion of thorium-uranium nuclear fuel,.
Construction of the two-megawatt thermal TMSR-LF1 reactor began in September 2018 and was scheduled to be completed in 2024. However, it was reportedly completed in August 2021 after the construction was accelerated. In August 2022, the Chinese Ministry of Ecology and Environment gave approval to the Shanghai Institute of Applied Physics (SINAP) to commission the reactor. An operating license was granted for the new reactor in June 2023. It achieved a sustained reaction (first criticality) on the 11th of October 2023.
The TMSR-LF1 uses fuel enriched to under twenty percent uranium-235. It has a thorium inventory of about one hundred and ten pounds and conversion ratio of about one tenth. A fertile blanket of lithium-beryllium fluoride (FLiBe) with ninety-nine and ninety-five one hundredths percent Li-7 is used, and fueled with uranium tetrafluoride (UF4).
The Shanghai Institute of Applied Physics said, “In October 2024, the world’s first thorium addition to a molten salt reactor was completed, making it the first in the world to establish a unique molten salt reactor and thorium-uranium fuel cycle research platform”.
On the 1st of November, the Institute announced that the TMSR-LF1 achieved the first conversion of thorium and uranium nuclear fuel.
The Institute said, “This marks the first time international experimental data has been obtained after thorium was introduced into a molten salt reactor, making it the only operational molten salt reactor in the world to have successfully incorporated thorium fuel. This milestone breakthrough provides core technological support and feasible solutions for the large-scale development and utilization of thorium resources in China and the development of fourth-generation advanced nuclear energy systems.”
Li Qingnu is the Deputy Director of the Shanghai Institute of Applied Physics Deputy Directo. She said, “Since first reaching criticality on 11 October 2023, the thorium-based molten salt reactor has been continuously generating heat through nuclear fission.” She explained that conventional commercial pressurized water nuclear reactors require periodic shutdowns and the opening of the pressure vessel top cover to replace the nuclear fuel when refueling is required. However, in contrast, the thorium-based molten salt reactor uses liquid fuel, with the nuclear fuel uniformly dissolved in the molten salt coolant and circulating with it, allowing for refueling without shutting down the reactor.
Li added, “This design not only improves fuel utilization but also significantly reduces the generation of radioactive nuclear waste, which is one of the advantages of thorium-based molten salt reactors.”
Dai Zhimin is the Director of the Shanghai Institute of Applied Physics. He said that the Institute’s next step is to accelerate technological iteration and engineering transformation, aiming to complete a one-megawatt thermal thorium-based molten salt reactor demonstration project and achieve demonstration applications by 2035.
Molten salt reactors (MSRs) utilize molten fluoride salts as their primary coolant at low pressure. They might operate with epithermal or fast neutron spectrums, and they can burn a variety of fuels. A great deal of the interest today in reviving the MSR concept relates to using thorium (to breed fissile uranium-233), where an initial source of fissile material such as plutonium-239 needs to be provided. There are a variety of different MSR design concepts, and a number of interesting challenges in the commercialization of many, especially with thorium.