The U.S. Nuclear Regulatory Commission issued a Safety Evaluation Report approving Terrestrial Energy Inc.'s (NASDAQ: IMSR) Postulated Initiating Events Topical Report for its Integral Molten Salt Reactor technology.

The approval covers Terrestrial Energy's methodology for identifying and evaluating events that may challenge safe operation of IMSR nuclear plants. The NRC accepted the company's final topical report submission in April 2026, according to the press release.

"We are pleased to report the timely issuance by the NRC of the SER on our PIE Topical Report," said Simon Irish, CEO of Terrestrial Energy.

Approved topical reports can be referenced in future operating license applications for nuclear plant operation, removing the need for repetitive re-evaluations and enabling standardized regulatory outcomes.

This approval follows the NRC's approval of IMSR's Principal Design Criteria in September 2025. Principal Design Criteria establish foundational safety and design requirements for key reactor systems.

Terrestrial Energy develops Generation IV nuclear plants using its Integral Molten Salt Reactor technology. The company designs IMSR plants to be small and modular for distributed supply of industrial heat and electricity.

The company stated it is working with regulators, suppliers, industrial partners and energy end-users to build, license and commission the first IMSR plants in the early 2030s.