TMSR-LF1

In January 2011, the Chinese Academy of Sciences (CAS) began the TMSR research and development project to create reactors which, among other advances, would use air cooling.^[6] Its budget was reportedly ¥3 billion ($444 million US).^[7] and is led by Xu Hongjie (徐洪杰), who previously headed the construction of the Shanghai Synchrotron Radiation Facility,^[8] through the Shanghai Institute of Applied Physics (SINAP), which now has MSR research and design facilities in the Jiading District.^[9] The initial project completed there was the TMSR-SF0, an electrically-heated (non-fissioning) simulator to aid development of a proposed "SF" (solid fuel, using a molten salt only for cooling) branch of TMSR, as well as to gain operational experience using molten salt more generally. The SF0 has two liquid FLiNaK heat transport loops.^[10]

The liquid fuel ("LF") design is based on the 1960s Molten-Salt Reactor Experiment at Oak Ridge National Laboratory in the US.^[11] The site selected for the TMSR-LF1 is part of an industrial park^[12] in a sparsely populated, arid region.^{[location note]} Site construction began in 2018.^[7] At the groundbreaking, a Taoist ceremony was held; after images of it went viral in China (an atheist state), CAS disciplined staff members, and issued a public apology.^[13] A reactor construction permit was issued by the Chinese National Nuclear Safety Administration in January 2020.^[14] Construction was expected to finish in August 2021, with testing to follow.^[15][16] In August 2022, the Chinese Ministry of Ecology and Environment informed SINAP that its commissioning plan for the LF1 had been approved.^[7] A ten-year operating license was issued in June 2023.^[17][18] For the first 5–8 years, it is to be run in batch mode, before converting to continuous mode.^[7]

Criticality was first achieved on 11 October 2023.^[19][20][21] On 17 June 2024, full power (2MW_t) operation was achieved, and on 8 October, it operated at full power for 10 days with thorium in the molten salt; Protactinium-233 was detected, indicating successful nuclear breeding.^[21]

The TMSR-LF1 is a Generation IV reactor constructed with the following specifications:^[22][23][24]

• Thermal power: 2MW
• Fuel salt: FLiBe (>99.95% Li-7) with fluorides of zirconium, uranium (HALEU: 19.75% U-235), and thorium
  • inlet temperature: 630 °C
  • outlet temperature: 650 °C
  • volume: 1.68 m³
  • flow rate: ~50 kg/s
• Coolant salt: FLiBe
  • inlet temperature: 560 °C
  • outlet temperature: 580 °C
  • flow rate: ~42 kg/s
• Cover gas: Argon (0.05 MPa)
  • volume: 1.6 m³
• Moderator: nuclear graphite
• Structural Material: UNS N10003 superalloy
• Lifetime: 10 years
  • equivalent full power days: 300
  • maximum full power days per year: 60

The reactor is located underground, seated at the bottom of a 14m (46 foot) deep dry well, which is capped at ground level, and above which rises a 20m (66 foot) tall roofed atrium.^[25]

A small modular reactor (SMR) based on the LF1, as well as a fuel salt research facility, is planned for the same site. New reactor specifications include: core graphite 3 m tall x 2.2 m wide, 700 °C operating temperature, 60 MW thermal output, and an experimental supercritical carbon dioxide-based closed-cycle gas turbine to convert the thermal output to 10 MW of electricity.^[1] Construction is slated to start in 2025, and be completed by 2029. The project would also include a high-temperature hydrolysis component, for hydrogen generation. Following the completion of the 10 MW project, in 2030 construction will begin on commercial SMRs of at least 100 MWe.^[19] These are likely to be sited in central and western China, and may also be built outside China in Belt and Road Initiative nations; as low-carbon power plants, they would help to achieve the Chinese government's 2060 goal of carbon neutrality.^[15]