NRC Issues Safety Evaluation Report Approving Terrestrial Energy's IMSR Postulated Initiating Events Topical Report
Topical Report's safety evaluation establishes another fundamental safety framework for future IMSR Plant licensed operation
Second recent approval of a Topical Report foundational to IMSR plant safe and compliant operation
Terrestrial Energy Inc. (NASDAQ:IMSR) ("Terrestrial Energy" or "the company"), a developer of small modular nuclear power plants using its Generation IV Integral Molten Salt Reactor (IMSR) today announced that the U.S. Nuclear Regulatory Commission (NRC) has issued its Safety Evaluation Report (SER) approving the company's Postulated Initiating Events (PIE) Topical Report. This follows the NRC's acceptance of the company's final Topical Report submission announced in April 2026.
The NRC's SER issuance is an approval of Terrestrial Energy's PIE methodology, which identifies and evaluates events that may challenge the safe operation of IMSR nuclear plant. This analysis is foundational to nuclear safety analysis and represents another important regulatory milestone as Terrestrial Energy systematically executes on its nuclear regulatory program.
"We are pleased to report the timely issuance by the NRC of the SER on our PIE Topical Report, this follows its acceptance of final submissions just last month," said Simon Irish, CEO of Terrestrial Energy. "The scope of this Topical Report is foundational to nuclear safety analysis and future IMSR Plant licensed operation."
Approved Topical Reports with their associated safety analyses can be referenced in future operating licensing applications for nuclear plant operation, removing the burden of repetitive re-evaluations and enabling standardized regulatory outcomes. They support faster review timelines, reduce uncertainty, and improve efficiency of the regulatory process.
This milestone demonstrates further process with Terrestrial Energy's multi-year engagement the NRC. It builds on prior successful regulatory actions, including the NRC's approval of IMSR's Principal Design Criteria announced in September 2025. Principal Design Criteria are the foundational safety and design requirements of key reactor systems. These agreed criteria represent regulatory acceptance of important mechanisms of IMSR safety, particularly those relating to IMSR inherent safety and reactor power control that deliver powerful load-following capability.
Together, these extensive safety analyses of IMSR performance with approvals establish the critical elements of the IMSR's licensing basis and reinforce the company's continued progress toward commercial deployments of multiple IMSR plants.
About Terrestrial Energy Inc.
Terrestrial Energy is a developer of Generation IV nuclear plants that use its proprietary Integral Molten Salt Reactor (IMSR). The IMSR captures the transformative operating benefits of molten salt reactor technology in a plant design that represents true innovation in capital efficiency, cost reduction, versatility, and functionality of nuclear energy supply. IMSR Plants are designed to be small and modular for distributed supply of low-cost, reliable, dispatchable, clean, high-temperature industrial heat and electricity, and to be customized for a dual-use energy role relevant to many industrial applications, such as petrochemical and chemical synthesis, and data center operation. In so doing, IMSR Plants extend the application of nuclear energy far beyond electric power markets. Their deployment will support the rapid growth of clean firm heat and power, delivering energy self-reliance, grid reliability, and economic growth. Terrestrial Energy uses an innovative plant design together with proven and demonstrated molten salt reactor technology and readily-available and inexpensive standard-assay low-enriched uranium in its fuel for a nuclear plant with a unique set of operating characteristics and compelling, transformative commercial potential. Terrestrial Energy is engaged with regulators, suppliers, industrial partners, and energy end-users to build, license and commission the first IMSR Plants in the early 2030s.
For more information, visit www.terrestrialenergy.com.
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