Official approval has been issued by Chinese authorities for the commissioning of a functional molten salt reactor based on thorium. The “Thorium Molten Salt Reactor – Liquid Fuel 1” (TMSR-LF1) is being constructed at the Hongshagang Industrial Cluster, Wuwei City, Gansu Province, and has been since 2018.

If the TMSR-LF1 is successful, it may pave the way for creating and erecting a larger demonstration facility by 2030. Additionally, it may result in the development of a TMSR fuel salt batch pyro-process demonstration plant, allowing the thorium-uranium cycle to be used by the early 2040s.

This makes it China’s first authorized thorium molten salt reactor

“The thorium-fueled molten salt experimental reactor operation application and related technical documents were reviewed, and it was considered that the application met the relevant safety requirements, and it was decided to issue the two MWt liquid fuel thorium-based molten salt experimental reactor an operating licence,” the National Nuclear Security Administration (NNSA) stated in a statement on June 7.

The World Nuclear Association (WNA) claims that thorium (Th) is more accessible than uranium (U). It is “fertile” rather than “fissile,” though, which means that it can only be utilised as fuel in conjunction with a fissile substance like reprocessed plutonium. Although utilising thorium as a major energy source has long been appealing, it has been challenging to economically extract its potential energy value.

The TMSR-LF1 reactor is an experimental liquid fluoride thorium reactor that uses a coolant salt of LiF-BeF2 and a fuel salt mixture of LiF-BeF2-ZrF4-UF4 [+ThF4]. It can function for up to ten years at a maximum temperature of 650C when powered by a mixture of thorium and uranium-235 that has been enriched to 19.75 percent by weight. The Molten-Salt Reactor Experiment carried out at Oak Ridge National Laboratory in the 1960s served as the inspiration for the liquid fuel concept.

The reactor is intended to test pyro-processing, refuelling, and continuous gas removal methods, research the stability and safety of its operation, and test a thorium-uranium fuel cycle, according to SINAP documentation.

According to the NNSA, SINAP must prioritize safety while operating TMSR-LF1. They must comply with operating license regulations and permit conditions to ensure the safe operation of the reactor. Although construction of the reactor was initially expected to be finished in 2024, it was completed earlier in August 2021 due to accelerated work.

If successful, China plans on building a larger one by 2030

The Ministry of Ecology and Environment gave SINAP permission to commission the TMSR-LF1 reactor in August of last year. Its fuel will have a U-235 enrichment of under 20 percent, a thorium stock of around 50 kg, and a conversion efficiency of about 0.1. With 99.95 percent Li-7 and UF4, the reactor will feed a lush layer of lithium-beryllium fluoride (FLiBe).

If the TMSR-LF1 is successful, China plans to build a 373 MWt reactor by 2030.