Terrestrial Energy Executes Other Transaction Authority Agreement With U.S. Department of Energy For Project TETRA

Terrestrial Energy Inc. (NASDAQ: IMSR) ("Terrestrial Energy" or "the Company"), a developer of small modular nuclear power plants using its Generation IV reactor technology, today announced that it has executed an Other Transaction Authority (OTA) agreement with the U.S. Department of Energy (DOE) for Project TETRA, a groundbreaking initiative to construct and operate a pilot reactor which will support Integral Molten Salt Reactor (IMSR) plant development. This announcement marks an important milestone in Terrestrial Energy's engagement with the Advanced Reactor Pilot Program, established by Executive Order 14301, under which the Company is targeting IMSR plant deployment facilitated by the DOE's accelerated authorization of pilot TETRA reactor operation.

The execution of an OTA demonstrates the Company's structured program, which will support IMSR plant commercialization and its leading market position in the advanced reactor sector. The agreement establishes a direct, streamlined collaboration with the DOE to review and authorize 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 authorization. Executed under DOE's authority at 42 U.S.C. § 7256(g), the OTA enables the Company to operate outside traditional federal contracting constraints, providing a flexible and agile framework designed for swift advanced reactor innovation.