TMSR-LF1 (Thorium Molten Salt Reactor) by Shanghai Institute of Applied Physics, CAS: status and timeline

TMSR-LF1 (Thorium Molten Salt Reactor)

Demonstrate that thorium molten salt reactors can operate reliably, convert thorium to fissile fuel, and enable China to leverage its vast thorium reserves for long-term energy independence.

ProtoStage 2 of 5

Operating since 2023. First thorium conversion Oct 2024. Heading toward 100 MWt demo by 2035.

Updated 1 Nov 2025Checked 11 Oct0 updates this week

Milestones

Next · 100 MWt demonstration reactor planned

Construction completedAug 2021Complete.
Operating license grantedJun 2023Complete.
First criticality achieved11 Oct 2023Complete.
First thorium addition and fuel conversionOct 2024Complete.
100 MWt demonstration reactor plannedTarget 2035Not yet reached.

Most important updates

Upcoming

2030Ongoing fuel cycle and materials testing (next)
2035100 MWt demonstration reactor planned

Current obstacles

Corrosion and materials degradationMolten salt at 650°C corrodes metals. Developing alloys for decades of operation is challenging.
Tritium production and controlLithium in the salt can breed tritium when hit by neutrons. Containing and accounting for tritium is a safety and licensing requirement.
Salt cleanup and reprocessingProcessing salt to remove fission products and recover uranium and thorium for reuse must be done safely and economically at scale.

Physics limits

Thermal efficiency constrained by salt propertiesFLiBe limits temperature above 750°C and operates near atmospheric pressure, limiting Rankine cycle efficiency.
Neutron activation of salt constituentsNeutrons hitting salt nuclei (lithium, beryllium, fluorine) produce radioactive species and helium gas over time, requiring periodic salt replacement and adding waste management complexity.

How it works

4 parts

Fuel dissolution

Uranium and thorium in molten salt

Uranium and thorium fluorides dissolve in FLiBe salt, which carries fuel and cools the reactor.

Neutron capture

Thorium-232 becomes fissile U-233

Thorium-232 captures neutrons, beta-decays to uranium-233, which is fissile and sustains the reaction.

Heat removal

Secondary salt loop transfers heat

Hot salt flows to a heat exchanger, heating a secondary loop that boils water for power.

Online processing

No shutdown refueling

Salt processes while running, removing products and adding fresh fuel.

Spec sheet

Spec	TMSR-LF1 (Thorium Molten Salt Reactor)
Thermal power	2 MWt^R (reported)
Salt outlet temperature	~650°C^E (estimated)
Thorium inventory	~50 kg^R (reported)
Uranium-235 enrichment	<20%^R (reported)
Thorium conversion ratio	~0.1^R (reported)

^R reported by the company · ^E our estimate

Papers & demos

4 items

Nov 2025talk
World's first thorium-to-uranium fuel conversion in a molten salt reactor announced (opens world-nuclear-news.org)Breakthrough demonstrating the thorium fuel cycle works, enabling future reactors to breed fuel.
Oct 2024demo
First thorium addition to molten salt reactor completed (opens world-nuclear-news.org)Proof that thorium can be used as fuel and bred to uranium-233 in a molten salt reactor.
Oct 2023demo
TMSR-LF1 achieves first criticality (opens world-nuclear-news.org)First sustained nuclear reaction confirming design works and enabling thorium conversion experiments.
Jun 2023demo
Operating license granted for TMSR-LF1 (opens world-nuclear-news.org)Regulatory approval to begin experimental operations and thorium fuel trials.

Update log

5 updates

About Shanghai Institute of Applied Physics, CAS

The team behind TMSR-LF1 (Thorium Molten Salt Reactor)

Shanghai Institute of Applied Physics, CAS

TMSR-LF1 thorium molten salt reactor, nuclear energy research

A national nuclear research institute under CAS with campuses in Shanghai and Wuwei. Leads China's thorium molten salt reactor program, achieving world's first thorium-to-uranium conversion in 2025.

Operates TMSR-LF1, a 2 MWt experimental thorium molten salt reactor in Wuwei, Gansu.
Achieved world's first thorium-to-uranium conversion in a molten salt reactor (Nov 2025).
Plans 100 MWt demonstration reactor by 2035 to leverage China's vast thorium reserves.

english.sinap.cas.cn (opens english.sinap.cas.cn)Company profile →

Founded: 195967 yrs
Headquarters: China
Status: Government
Valuation: government
Staff: ~798Dec 2024
Works in: EnergyFission
Coverage: 1 program · 5 updateslatest 1 Nov 2025checked 11 Oct
Partners: Institute of Nuclear Energy Tech, Tsinghua (opens inet.tsinghua.edu.cn)Chinese Academy of Sciences (opens cas.cn)

Spec

TMSR-LF1 (Thorium Molten Salt Reactor)

Thermal power

2 MWt^R (reported)

Salt outlet temperature

~650°C^E (estimated)

Thorium inventory

~50 kg^R (reported)

Uranium-235 enrichment

<20%^R (reported)

Thorium conversion ratio

~0.1^R (reported)

TMSR-LF1 (Thorium Molten Salt Reactor)

Milestones

Most important updates

Upcoming

Current obstacles

Physics limits

How it works

Uranium and thorium in molten salt

Thorium-232 becomes fissile U-233

Secondary salt loop transfers heat

No shutdown refueling

Spec sheet

Papers & demos

Update log

Sat 1 Nov 2025

Oct 2024

Wed 11 Oct 2023

Jun 2023

2021

About Shanghai Institute of Applied Physics, CAS

Current obstacles

Physics limits

How it works

Uranium and thorium in molten salt

Thorium-232 becomes fissile U-233

Secondary salt loop transfers heat

No shutdown refueling

Spec sheet

Papers & demos

Update log

Sat 1 Nov 2025

Oct 2024

Wed 11 Oct 2023

Jun 2023

2021

About Shanghai Institute of Applied Physics, CAS