Commercial Advantages

IMSR® cogeneration plants are a carbon-free and cost-competitive alternative to burning fossil fuels for industrial heat

The use of molten salt technology drives the many commercial advantages of IMSR® cogeneration plants. It permits IMSR® plants to operate with high safety at high temperature and lower pressure, benefiting from the transformative commercial advantages of both.

IMSR® Core-unit Cutaway view.

The importance of high thermal efficiency

The efficiency of the machines in our modern is world is defined by the amount of thermal energy that can be captured as mechanical energy. It is mechanical energy that spins an electric generator to make electricity or propels cars, or planes or ships. It is mechanical energy used for commercial purposes. The more mechanical energy a machine captures, the more efficient and commercially attractive it is. That efficiency is called the thermal efficiency of a machine.

Thermal efficiency varies with the temperatures of thermal energy, high temperature equals high efficiency, low temperature equals low efficiency. Thermal efficiency translates directly to financial efficiency and commercial performance reflected in measures such as return-on-capital.

Coal, oil and natural gas fired power plants operate at high efficiency because coal, oil and natural gas combustion creates heat at high temperature (585 degree C steam). They have a thermal efficiency that exceeds 45%. But burning fossil fuels creates air pollution that contributes to climate change.

Conventional nuclear power plants are carbon-free but inefficient machines, because conventional nuclear technology generates heat at low temperature (290 degree C steam). They have a thermal efficiency that is low; 30% for small plants, 33% for large plants.

IMSR® cogeneration plants are efficient machines. The IMSR® generates heat at high temperature (585 degree C steam). They have a thermal efficiency of 44%, a near 50% efficiency improvement. Conventional nuclear power plants use water as the reactor coolant and must operate at low temperatures.

In addition to cost and return on capital, thermal efficiency impacts all aspects of plant operation including the efficiency of land-use, material use, and waste production.

Technology and design choices reduce costs and accelerate speed-to-market

In industrial heat markets, IMSR® plants can be cost-competitive with thermal energy (heat) from burning natural gas and heating oil. They provide heat at an in-furnace cost of less than U.S. $6 per MMBtu.

In electric power markets, IMSR® plants generate dispatchable electricity at a levelized cost of under U.S. $50 per megawatt-hour. This is cost-competitive with natural gas and coal generation, and they never face the prospect of carbon penalties.

The IMSR® low-pressure operation avoids the considerable engineering complexity and costs of the high-pressure operation required for water-cooled conventional reactors.

Simple, fast, modular plant construction

IMSR® cogeneration plants are smaller and simpler to build than today’s conventional nuclear power plants. They are are right sized for today’s industrial needs.

They use a modular design for ease and speed of construction, and each module is mass-manufactured in factory settings using the latest advanced manufacturing methods. This approach makes them easily transportable by truck or rail for on-site modular assembly.

This modular approach allows for building an IMSR® plant in under four years, less than half the time for conventional nuclear plants. Selecting an IMSR® plant means lower construction and financing costs.

It is the combination of high-temperature and low-pressure operation, inherent and passive safety, smaller size, modularity, and versatility that creates the transformative commercial potential of IMSR® cogeneration plants.  IMSR® plants are a carbon-free and cost-competitive alternative to burning fossil fuels.


1. Lazard: Natural gas fuel cost assumption as of October 2020. By August 2021, natural gas prices had risen by more than 50%.
2. IMSR® is Generation IV non-light water small modular reactor (SMR) design.
3. EIA: Based on Generation III light water reactor (LWR) SMR design.
4. Lazard: Generation III (LWR and PHWR) in large ~1 GWe design formats.
5. EIA: Technology is assumed to be photovoltaic (PV) with single-axis tracking. Lazard: The low represents a single-axis tracking system and high case represents a fixed-tilt system.
Levelized Cost Of Energy, Lazard, October 2020
Levelized Costs of New Generation Resources, Annual Energy Outlook 2021, Energy Information Administration
Assumptions to the Annual Energy Outlook 2021: Electricity Market Module, Annual Energy Outlook 2021, Energy Information Administration

Learn More About Terrestrial Energy

Terrestrial Energy is an industry-leading technology company committed to delivering reliable, emission-free, and cost-competitive nuclear energy with a truly innovative advanced reactor design, the Integral Molten Salt Reactor (IMSR®).