IMSR by Terrestrial Energy: status and timeline

IMSR

The IMSR is a 442-MWt molten salt reactor producing 390 MWe (two units) and industrial heat. Fuel and coolant are one integrated molten salt fluid.

ProtoStage 2 of 5

NRC approved principal design criteria in 2025. Texas A&M site work underway. Early 2030s deployment targeted.

Updated 22 Jan 2026Checked 10 Oct0 updates this week

Milestones

Next · Texas A&M RELLIS site characterization and environmental review

Terrestrial Energy founded2013Complete.
Pre-licensing design review begins with CNSC2016Complete.
IMSR design review stage 1 completed with CNSC2017Complete.
NRC principal design criteria approval10 Sep 2025Complete.
Business combination and Nasdaq listing (IMSR)29 Oct 2025Complete.
Texas A&M RELLIS site characterization and environmental reviewTarget 2026Current milestone.
NRC permit-to-construct application submissionTarget 2028Not yet reached.
IMSR commercial operation at RELLISTarget 2032Not yet reached.

Most important updates

Upcoming

2026Texas A&M RELLIS site characterization and environmental review (next)
2028NRC permit-to-construct application submission
2029IMSR construction begins at Texas A&M RELLIS
2032IMSR commercial operation at RELLIS
2032First IMSR criticality

Current obstacles

First-of-a-kind licensing timeline with NRCNo U.S. commercial molten salt reactor has been licensed before. NRC reviews are thorough, and approval could take 5–7 years from permit application.
Cost competitiveness with natural gas and renewablesAt $2–4 per megawatt-hour natural gas, the IMSR must operate at <$60/MWh to compete for industrial heat. Achieving this requires scaling production.

Physics limits

Neutron activation of reactor materialsMolten salt reactors still face neutron damage to metals, just like conventional reactors. Over decades, structural materials become brittle and radioactive.
Thermal cycling limits fatigue lifeTemperature swings from startup, shutdown, and load changes cause thermal stress. Salt chemically attacks metals under stress, shortening operational life.

How it works

4 parts

Integral design

One vessel, no separate coolant loops

Fuel salt and cooling salt are the same fluid in one reactor vessel. This eliminates piping breaks and external coolant loops.

Heat transfer

Salt-to-salt heat exchanger inside the vessel

Heat flows from the fuel region to a secondary salt loop via internal heat exchangers, which then powers the turbine or supplies industrial heat.

Electricity

Brayton or Rankine cycle turbine

The high-temperature salt output (585°C) can drive a Brayton cycle turbine for efficiency or a steam Rankine cycle for conventional operation.

Industrial heat

Direct heat for hydrogen, desalination, process chemistry

150°C+ process heat is available for industrial applications that need high temperatures, from hydrogen production to steel making.

Spec sheet

Spec	IMSR
Thermal power per core	442 MWt^R (reported)
Electric power (two-unit configuration)	390 MWe^R (reported)
Operating temperature	585°C^R (reported)
Fuel enrichment	SALEU <5% U-235^R (reported)
First commercial location	Texas A&M RELLIS campus, College Station, TX^R (reported)

^R reported by the company

Update log

4 updates

About Terrestrial Energy

The team behind IMSR

Terrestrial Energy

IMSR, integral molten salt reactor, SMR

Terrestrial Energy develops the Integral Molten Salt Reactor (IMSR), a 390-MWe molten salt reactor for electricity and industrial heat. The company went public on Nasdaq in October 2025 and is deploying its first commercial reactor at Texas A&M-RELLIS in the early 2030s.

Terrestrial Energy went public on Nasdaq (IMSR) in October 2025 via HCM II merger, raising $292M.
The NRC approved its IMSR principal design criteria in 2025, the first for molten salt reactors.
Texas A&M selected Terrestrial to build a commercial IMSR at RELLIS, targeting early 2030s operation.

terrestrialenergy.com (opens terrestrialenergy.com)Company profile →

Founded: 201313 yrs
Headquarters: CanadaUnited States
Status: Public
Listed: IMSR (opens google.com)NASDAQ
Valuation: $292Mdeal valueOct 2025
Raised: $292M2 rounds
Last round: HCM II Merger (NASDAQ listing) · $292MOct 2025
Works in: EnergyFission
Coverage: 1 program · 6 updateslatest 22 Jan 2026checked 10 Oct
Customers: Texas A&M University System (opens tamu.edu)
Partners: U.S. Department of Energy (opens energy.gov)
People: Simon Irish (opens terrestrialenergy.gcs-web.com)Founder & President/CEODavid LeBlanc (opens terrestrialenergy.gcs-web.com)Founder & Chief Technology Officer

Spec

IMSR

Thermal power per core

442 MWt^R (reported)

Electric power (two-unit configuration)

390 MWe^R (reported)

Operating temperature

585°C^R (reported)

Fuel enrichment

SALEU <5% U-235^R (reported)

First commercial location

Texas A&M RELLIS campus, College Station, TX^R (reported)

IMSR

Milestones

Most important updates

Upcoming

Current obstacles

Physics limits

How it works

One vessel, no separate coolant loops

Salt-to-salt heat exchanger inside the vessel

Brayton or Rankine cycle turbine

Direct heat for hydrogen, desalination, process chemistry

Spec sheet

Update log

Thu 22 Jan

Tue 6 Jan

Wed 10 Sep 2025

Tue 4 Feb 2025

About Terrestrial Energy

Current obstacles

Physics limits

How it works

One vessel, no separate coolant loops

Salt-to-salt heat exchanger inside the vessel

Brayton or Rankine cycle turbine

Direct heat for hydrogen, desalination, process chemistry

Spec sheet

Update log

Thu 22 Jan

Tue 6 Jan

Wed 10 Sep 2025

Tue 4 Feb 2025

About Terrestrial Energy