Terrestrial Energy Submits Topical Report to NRC for IMSR Plant Classification

Terrestrial Energy has submitted a Topical Report to the US Nuclear Regulatory Commission (NRC) regarding its Integrated Molten Salt Reactor (IMSR) plant. The report asks the NRC to confirm that the construction of the Thermal and Electric Facility (TEF) component of the IMSR plant does not fall under "nuclear construction" regulations in the United States.

The IMSR is a Generation IV reactor designed to use molten salt as both fuel and coolant, with integrated components capable of supplying heat directly to industrial facilities or generating electrical power. The plant design separates into two parts: the Nuclear Facility, which contains standardized nuclear systems, and the TEF, which includes non-nuclear heat transfer, steam supply, and electric systems for commercial power generation and thermal energy supply.

Terrestrial Energy states that its submission demonstrates that the plant's nuclear systems do not rely on the TEF for safe operation and that any failure originating in the TEF is isolated from the nuclear systems. The report incorporates elements of the company's Postulated Initiating Events methodology, which the NRC has already approved.

Regulatory and Financial Implications

NRC approval of the TEF Topical Report would allow the TEF, which can be customized for each site, to be built and operated using an auxiliary heat source, such as natural gas, as a bridge to nuclear power. This could occur before a nuclear construction permit and operating license are granted for the nuclear portion of the plant.

According to Simon Irish, CEO of Terrestrial Energy, this submission could alter how an IMSR Plant is regulated, built, and financed. He noted that with NRC approval, only the nuclear portion of the plant would follow the nuclear licensing timeline, while the rest would become a conventional industrial project. This approach could provide customers with earlier power and heat and offer financing partners a bankable construction phase, representing a fleet-wide advantage for IMSR Plants.

Terrestrial Energy is developing a pipeline of IMSR Plant projects, including a planned facility at the Texas A&M-RELLIS site in Bryan, Texas. In September, the company was selected as the supplier of advanced nuclear plant technology for Ameresco Inc.'s power plant project at the US Army's Aberdeen Proving Ground in Maryland.

The NRC has been engaged in pre-application activities with Terrestrial Energy for the IMSR since 2019. This is the third of at least five Topical Reports the company plans to submit to the regulator during 2026.

JAIF Report Details Economic Impact of Nuclear Power Plants

The Japan Atomic Industrial Forum (JAIF) has released a report detailing the economic impact of a single nuclear power plant throughout its operational lifecycle. The analysis, presented by JAIF President and CEO Hideki Masui, estimates a total economic impact of approximately JPY4.3 trillion across the Japanese economy for each plant. This figure includes direct and primary ripple effects, utilizing data from the government's 2025 Working Group on Verification of Power Generation Costs and Japan's 2020 Input-Output Tables.

During the construction phase, a single nuclear power plant project is projected to create around 14,000 jobs annually. From an energy security standpoint, JAIF noted that over 90% of nuclear plant equipment is procured domestically. Additionally, the report highlights a fuel stockpiling effect equivalent to 2.9 years, indicating the duration electricity generation could be maintained using existing nuclear fuel reserves in Japan. Environmentally, nuclear power generation produces no carbon dioxide emissions.

Policy Context and Future Plans

JAIF's analysis aligns with recent government initiatives, including the Ministry of Economy, Trade and Industry's draft target to replace up to five nuclear reactors by the 2040s and 11-14 reactors by the 2050s. In February 2023, Japan's Cabinet approved a policy allowing the construction of new nuclear power reactors and extending the operational lifespan of existing reactors from 40 to 60 years.

The government's 7th Basic Energy Plan, adopted in February 2025, aims to increase nuclear electricity generation from 8.5% in fiscal 2023 to approximately 20% by fiscal 2040. Concurrently, renewable energy's share is projected to rise from 22.9% to 40%-50%, while fossil fuels' share is expected to decrease from nearly 69% to 30%-40%.

Kansai Electric Power Company announced plans in July of the previous year to survey the Mihama nuclear power plant site in Fukui Prefecture for a potential new reactor to replace unit 1, which was decommissioned in 2015. Reports indicate that Kansai is considering the SRZ-1200 advanced light water reactor, developed by Mitsubishi Heavy Industries. This 1,200 MWe reactor, launched in September 2022, is designed to meet enhanced regulatory safety standards. JAIF noted that assessing the economic impact of newly built advanced light-water reactors is challenging due to the absence of such reactors in Japan.

Zap Energy Achieves DOE Milestones for Fusion Capacitor Development

The U.S. Department of Energy (DOE) has approved two capacitor development milestones for Zap Energy under the Milestone-Based Fusion Development Program. These approvals cover a detailed design for a pulsed power capacitor engineered for the repetition rate and operating lifetime required in a fusion power plant, and a prototype capacitor designed, manufactured, and tested by Zap Energy.

These milestones indicate advancements in long-life capacitor design and the U.S.-based manufacturing capabilities necessary for large-scale production of these components. Pulsed power, delivered by high-voltage capacitor banks, is a critical technology for various fusion energy approaches, including Zap Energy’s sheared-flow-stabilized Z pinch. Developing capacitors that can operate at high repetition rates over billions of pulses is a step toward commercial fusion power plants.

Commercial Fusion Requirements

Zabrina Johal, CEO of Zap Energy, stated that commercial fusion requires reliable, repeatable, and power-plant-scale operation of technologies surrounding the fusion core. She noted that pulsed power is a critical enabling technology, and these milestones demonstrate progress toward the long-life, high-repetition-rate systems needed for commercial fusion plants, while also building manufacturing capability within the United States.

Pulsed power capacitors store electrical energy and release it in rapid bursts. In pulsed fusion, these bursts help drive fuel into extreme conditions for fusion reactions. While commercial units are typically rated for about 100,000 pulses, a commercial power plant operating for 20 years at 10 pulses per second would require individual capacitors to withstand approximately 6 billion pulses.

Capacitor Specifications and Testing

Zap Energy's detailed design is for a 35-kilovolt, actively-cooled capacitor rated for 50,000 amps of peak current, projected to last 6 billion pulses. It incorporates self-healing metallized polypropylene film, which degrades gradually, and uses multiple capacitor sections in series to reduce the voltage seen by the film. Integrated active cooling enables continuous operation at 10 pulses per second.

The prototype is a compact, 2.8-pound epoxy-potted capacitor using the same multi-section winding approach. Zap Energy performed the winding, arc spraying, assembly, potting, and testing in-house, cycling the unit hundreds of times at 8 kilovolts and over 7,000 amps. Its capacitance remained stable within 0.25% throughout the test campaign, exceeding all prototype milestone criteria.

Supply Chain and Future Development

Ryan Umstattd, Zap’s VP of Federal Programs, explained that a goal of the DOE Milestone Program is to support the fusion supply chain across various fusion approaches and establish new U.S.-based manufacturing. He added that while long-lifetime, high-repetition-rate capacitors will eventually be needed by the thousands in fusion power plants, the initial step involves developing designs, manufacturing techniques, and qualification standards.

These approvals followed a review by an independent panel of experts convened by the DOE. Zap Energy's next steps include testing the designs to higher voltages, longer lifetimes, and with voltage reversals for implementation in future Zap fusion power banks.