Terrestrial Energy Inc and Oklo Inc have executed agreements with the US Department of Energy for a pilot reactor that will support Integral Molten Salt Reactor plant development, and a radioisotope pilot plant, respectively.
“The execution of an Other Transaction Authority (OTA) demonstrates the company’s structured programme, which will support Integral Molten Salt Reactor (IMSR) plant commercialisation and its leading market position in the advanced reactor sector,” Terrestrial Energy said.
“The agreement establishes a direct, streamlined collaboration with the Department of Energy (DOE) to review and authorise the design and safe operation of the TETRA reactor, a molten salt-fueled, graphite-moderated reactor that uses standard assay, low-enriched UF4-based fuel (SALEU) containing less than five percent U-235. This agreement enables Terrestrial Energy to move quickly from design to operation under DOE authorisation … the OTA enables the company to operate outside traditional federal contracting constraints, providing a flexible and agile framework designed for swift advanced reactor innovation.”
Terrestrial Energy CEO Simon Irish said: “The agreement sits on our development centre-path, allowing the company to expedite key elements of its programme to prepare licensing applications for commercial plant operation. The pilot TETRA reactor project affirms our position as a leading advanced reactor innovator and will demonstrate our ability to deliver the innovations necessary for clean, firm and affordable energy in a competitive timeframe.”
Terrestrial Energy’s Project TETRA was among 11 advanced reactor projects selected by the DOE in August last year for the Advanced Reactor Pilot Program. The pilot programme, announced in June, aims to expedite the testing of advanced reactor designs that will be authorised by the department at sites located outside of the national laboratories. Part of the Reforming Nuclear Reactor Testing at the Department of Energy executive order signed by President Donald Trump in May, its goal is “to construct, operate, and achieve criticality of at least three test reactors using the DOE authorisation process by 4 July 2026”.
Under the programme, each company will be responsible for all costs associated with designing, manufacturing, constructing, operating, and decommissioning their test reactors, but seeking DOE authorisation under the Atomic Energy Act will help them unlock private funding and provide a fast-tracked approach to future commercial licensing activities, the department said.
Project TETRA includes the completion of key testing that is essential to support licensing applications for the construction and operation of commercial IMSR plants in the USA, Terrestrial Energy said.
In September 2025, Terrestrial Energy was separately selected for the DOE Fuel Line Pilot Program, “demonstrating the company’s broad engagement with DOE programs to expedite commercial operation of small and modular nuclear plants that use advanced reactor technologies”, Terrestrial Energy noted.
Terrestrial’s IMSR is a 4th generation reactor that uses molten salt as both fuel and coolant, with integrated components, which can supply heat directly to industrial facilities or use it to generate electrical power. The use of molten salt as both fuel and coolant also enables passive, or inherent, safety features to be built into the reactor design. The design integrates the primary reactor components, including the graphite moderator, into a sealed and replaceable reactor core unit with an operating lifetime of seven years. The plant’s thermal and electric power supply systems can be customised to meet specific site demand requirements, and can support distributed generation for energy-intensive industry.
Radioisotope pilot facility
Oklo has also signed an Other Transaction Authority with the DOE to support the design, construction, and operation of a radioisotope pilot plant under the Reactor Pilot Program.
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A render of Atomic Alchemy’s radioisotope pilot facility (Image: Hillside Architecture)
Atomic Alchemy Inc – an Oklo subsidiary – will use the Radioisotope Pilot Facility to lay the groundwork for future commercial plants that make medical and research radioisotopes in the USA. These radioisotopes are essential for diagnosing cancer, treating disease, powering medical research, and supporting national security.
“This OTA establishes a framework for execution and risk reduction,” said Oklo co-founder and CEO Jacob DeWitte. “By building and operating a pilot reactor, we generate the data and experience to streamline future commercial deployments, improve regulatory efficiency, and deliver long-term value.”
With the Other Transaction Authority now in place, Atomic Alchemy will focus its near-term resources on building the Radioisotope Pilot Facility under DOE authorisation. As part of this learn-first-then-scale strategy, Atomic Alchemy has withdrawn its previously submitted Nuclear Regulatory Commission construction permit application for the Meitner-1 commercial radioisotope production facility at Idaho National Laboratory to focus on the Radioisotope Pilot Facility.