NRC approves Terrestrial Energy IMSR principal design criteria

Terrestrial Energy announced that the U.S. Nuclear Regulatory Commission has issued its Safety Evaluation on the Principal Design Criteria for Integral Molten Salt Reactor Structures, Systems, and Components following the company’s submission of its topical report to the agency. The NRC’s Safety Evaluation of Terrestrial Energy’s IMSR, the first of its kind to be completed for a molten fuel salt reactor designed for commercial use, approved the IMSR’s use of temperature as the inherent control mechanism for power control. A topical report allows for NRC review of a safety-related topic and leads to a Safety Evaluation, which can be referenced in a future licensing application. This regulatory approval avoids the need for re-adjudication of important topics of reactor safety and increases the efficiency of the licensing process. Principal Design Criteria of the nuclear reactor are the foundational safety requirements, quality standards, and design requirements of key plant systems, structures and components. These criteria ensure that the reactor is designed to operate safely, effectively, and in manner with nuclear regulations. This topical report has established the criteria for all major IMSR plant systems including the use of IMSR inherent reactivity control of fission power. The IMSR manages the fission process through its inverse relationship with the molten salt temperature, creating a reactor with inherently stable power dynamics.