Molten Salt Nuclear Reactor that will make nuclear as cheap as natural gas passes first certification hurdle

Terrestrial Energy’s Molten Salt Reactors completed phase 1 of the vendor design review – the first advanced reactor to do so – is a landmark achievement. It places the company as an early leader in a fast growing technology sector. The IMSR nuclear power plant is a transformative energy technology that is now one step closer to making a major contribution to the world’s growing demand for low-cost, clean and reliable energy.”

The Vendor review involves three phases:
1. a pre-licensing assessment of compliance with regulatory requirements;
2. an assessment of any potential fundamental barriers to licensing; and
3. a follow-up phase allowing the vendor to respond to findings from the second phase.

Terrestrial Energy’s Integral Molten Salt Reactor (IMSR®) is designed to meet the rapidly rising demand for breakthrough energy technologies that can deliver clean, scalable, and cost-competitive heat and power to displace fossil-fuel combustion starting in the 2020s. The IMSR® is a fundamentally different reactor. It employs advanced molten-salt technology, which creates a far superior system to harness clean bountiful energy of the atom simply, safely and economically.

IMSR® power plants are far simpler to build and operate than conventional nuclear power plants. They cost less than USD $1 billion, can be built within 4 years with much lower project risk, and can be financed by ordinary means.

IMSR® power plants are low-risk and cost-competitive clean-energy alternatives in North American and many other markets. In electric-power markets, IMSR® plants can dispatch power at under USD $50 per MWh (levelized cost), cost-competitive with NGCC for power generation, and probably more so with a volatility-adjusted price of natural gas; they are more cost-competitive when compared to coal. In industrial heat markets, IMSR® plants are also cost-competitive with natural gas; they have an in-furnace cost of less that USD $6 per MMBtu, within USD $1 of current in-furnace natural gas costs.

Using advanced molten salt reactor technology, IMSR® power plants are simpler than the Conventional Reactor power plants in the market today, which are pressurized-water reactors. IMSR® power plants are smaller, and with modular design and construction, can be built within 4 years and financed by ordinary means. IMSR® power plants will be cost-competitive with fossil fuels even in the absence of CO2 emission penalties.

Molten salt reactors use fuel dissolved in a molten fluoride or chloride salt which functions as both the reactor’s fuel and its coolant. This means that such a reactor could not suffer from a loss of coolant leading to a meltdown. Terrestrial’s IMSR integrates the primary reactor components, including primary heat exchangers, to a secondary clean salt circuit, in a sealed and replaceable core vessel. It is designed as a modular reactor for factory fabrication, and could be used for electricity production and industrial process heat generation.

Earlier this year, Terrestrial Energy began a feasibility study for the siting of the first commercial IMSR at Canadian Nuclear Laboratories’ (CNL) Chalk River site. It has also said it intends to submit an application to the US Nuclear Regulatory Commission for a design certification or construction permit in late 2019.

The Canadian Nuclear Safety Commission (CNSC) has completed the first phase of a vendor design review of Terrestrial Energy Inc’s Integrated Molten Salt Reactor (IMSR).

The CNSC announced yesterday that, based on the documentation submitted by Terrestrial Energy, the company had demonstrated an understanding of the regulator’s requirements applicable to the design and safety analysis of the 400 MWt IMSR, known as IMSR400. The company has also demonstrated its intent to comply with CNSC regulatory requirements and expectations for NPPs, and is integrating Fukushima lessons learned into IMSR design provisions, the regulator said.

Terrestrial Energy will need to undertake additional work to address some of the review’s findings, including the need to establish robust quality-assured processes for design and safety analysis activities.

Several features are currently at the conceptual level of design and will require additional technical information, based on research and development and design activities, the CNSC said, while some design features will need further consideration because of the novel design of the IMSR400.

Further work will be needed to predict core behaviour in the presence of damaged core components – although the CNSC acknowledges that the definition of core damage as set out in current regulations, which were drawn up based on operating experience from water-cooled reactors, may not be applicable to the IMSR design. Terrestrial Energy will also be required to complete further safety analysis work relating to core damage, and to provide further information on how it will validate predictions of performance as the reactor ages.

In the second phase of the review, Terrestrial Energy will also be required to demonstrate that human factors in design have been appropriately addressed in its operability and maintainability programs, which are currently under development.

The IMSR® is a liquid-fuel reactor system, rather than a solid-fuel system, as is used exclusively in conventional reactors. The IMSR® dissipates heat using a molten salt. Salts are thermally stable and excellent heat-transfer fluids, ideal for dissipating heat from the fission process simply and safely. In a molten salt reactor (MSR), salt provides a fluid medium to carry a nuclear fuel—in the case of the IMSR®, a low-enriched-uranium fluoride salt. The IMSR® provides simple, safe, and natural mechanisms for heat dissipation. It is a far superior system for the simple passive dissipation of fission heat. The use of a molten salt is at the heart of many engineering and commercial virtues of the IMSR®.

An IMSR® power plant generates 400 MWth of thermal energy (190 MWe) with a thermal -spectrum, graphite-moderated, molten-fluoride-salt reactor system, fueled by low-enriched uranium (less than 5% 235U). It incorporates the approach to MSR design and operation researched, demonstrated and proven by the ARE and MSRE test reactors at Oak Ridge National Laboratory (ORNL); these were further developed under the DMSR program.

The IMSR® improves upon the earlier ORNL MSR designs through various innovations that are pragmatic and commercial. The key challenge to MSR commercialization is graphite’s limited lifetime in a reactor core, which is a function of reactor power. Commercial power reactors require high core energy densities to be economical, but high power densities significantly reduce the lifetime of the graphite moderator requiring its replacement; this is challenging to do simply, safely and economically in an industrial environment. The key IMSR® innovation is an elegant solution to this challenge – the integration of the primary reactor components, including the graphite moderator, into a sealed and replaceable reactor core, the IMSR® Core-unit, which has an operating lifetime of 7 years. The IMSR® Core-unit is simple and safe to replace, it supports high utility factors for IMSR® power plants and high capital efficiency. It also ensures that the materials’ lifetime requirements of all other reactor core components are met; the challenge of achieving these requirements is often cited as an impediment to immediate commercialization of MSRs. The result is a power plant that delivers the combination of high energy output, simplicity and ease of operation, and cost-competitiveness essential for widespread commercial deployment. IMSR® power plants are a new clean energy alternative.