Nuclear fusion reactors can generate energy by fusing (i.e., joining) two light atomic nuclei to form a heavier nucleus. These fusion reactions release huge amounts of energy, which can then be converted into electrical power without emitting greenhouse gases.

One of the most reliable and promising fusion reactor designs is the tokamak. Tokamaks are fusion reactors that use a doughnut-shaped magnetic field to confine and heat plasma (i.e., superhot, electrically charged gas) for the time necessary for fusion reactions to take place.

Despite their potential for the generation of large amounts of clean energy, future tokamaks face huge challenges in managing the intense heat produced by fusion reactions. One major problem is the fact that the confined plasma can interact with the walls of the reactors, damaging them and adversely impacting both their durability and performance.

Researchers at the TCV tokamak experiment at École Polytechnique Fédérale de Lausanne (EPFL) recently discovered a new form of plasma radiation that could prevent tokamaks from overheating. It would allow them to shed excess heat and thus potentially boost their performance over time. The new technique they proposed, which they dubbed X-point target radiator (XPTR), was introduced in a paper published in Physical Review Letters.

Kenneth Lee is first author of the paper. He said, “Reducing divertor heat loads is a key challenge for future fusion power plants. One promising approach, the X-point radiator, dissipates plasma energy near the X-point, but scalability is uncertain due to its proximity to the core. We investigate experimentally the effect of adding a secondary X-point along the divertor channel to broaden operational range and maintain core plasma confinement. This concept is known as the X-point target divertor.”

In tokamaks, an X-point is a location where magnetic field lines run purely toroidally. This is central in shaping the plasma and guiding heat away from the core via a narrow magnetic funnel known as a ‘divertor’. X-point radiators are plasma operating conditions in which a large fraction of the plasma heat is converted into uniform radiation in proximity to the X-point.

In their paper, Lee and his colleagues perform experiments in which another X-point is introduce along the divertor. This occurs outside of the zone in which the plasma is confined. Adding this secondary X-point could further permit the removal of excess heat. This would prevent damage to the tokamak and enhances its durability.

Lee explained, “We leverage TCV tokamak’s unique magnetic shaping flexibility to introduce a secondary X-point, and we discovered localized radiation (the ‘XPTR’) far from the plasma core, which preserves core performance while significantly reducing divertor heat load. We found that the X-point target radiator is highly stable and can be sustained over a wide range of operational conditions, potentially offering a much more reliable method for handling power exhaust in a fusion power plant.”

In the initial tests, the approach introduced by the researchers was found to perform remarkably well. It removed excess heat from the magnetically confined plasma more effectively than conventional setups.

This new X-point target configuration is set to be implemented in next-generation tokamak devices that are being developed by Commonwealth Fusion Systems in collaboration with Massachusetts Institute of Technology (MIT).

Lee added, “We are now conducting new high-power experiments to explore the parameter range of the X-point target radiator, complemented by state-of-the-art numerical simulations to better understand its underlying physical mechanisms. The next-generation tokamak, SPARC, plans to incorporate the X-point target divertor into its baseline design, making our findings timely and crucial.”

École Polytechnique Fédérale de Lausanne

China’s first commercial small modular nuclear reactor (SMR), Linglong-1, is now in the final installation phase. Located in Hainan Province at the Hainan Nuclear Power Co. Ltd. (HNPC) site, the Linglong-1 SMR is being developed by the China National Nuclear Corporation (CNNC).

According to China’s state-run Global Times, the Linglong-1 being developed by the CNNC is the world’s first land-based SMR to begin construction. It is expected to play a key role in reducing China’s carbon emissions.

The Linglong-1, also known as the ACP100, is a third-generation small, pressurized water reactor. It was fully developed in China and has independent intellectual property rights there. In 2016, the Linglong-1 became the first SMR in the world to pass a safety review by the International Atomic Energy Agency (IAEA).

Because of its size and ability to deliver power safely and steadily, the Linglong-1 has been referred to as a ‘nuclear power bank’. The Global Times reported that the reactor is part of China’s fourteenth Five-Year Plan (2021–2025), focusing on advanced nuclear technology.

According to the HNPC, the project is moving ahead as designed. Engineers are carrying out system tests, and preparations are being made for cold functional testing which is an important step before starting full operations.

SMRs like Linglong-1 are different from traditional nuclear power plants. They are smaller, safer, more modular and quicker to build. These reactors use passive safety systems. This means that they can shut down safely without human action or power. Their smaller size allows them to be used in many different locations, including industrial parks, mining areas, and regions that require a lot of energy.

Each Linglong-1 reactor can produce one hundred and twenty-five thousand kilowatts of electricity. That adds up to one billion kilowatt-hours annually, enough to power about five hundred and twenty-six thousand homes or around one million people.

By replacing coal-based power with nuclear energy from Linglong-1, China can reduce carbon dioxide emissions by about eight hundred and eighty thousand tons every year. This is equal to planting seven million five hundred thousand trees.

The CNNC says that the Linglong-1 fills a gap in China’s nuclear development and shows that the country can lead in SMR technology. Following the success of Hualong One, a full-size third-generation nuclear reactor, the Linglong-1 is the next step in China’s goal to innovate independently in nuclear energy. The SMR is expected to help power the Hainan Free Trade Port and support clean energy goals in the region.

The Linglong-1 will also help China to meet its national climate targets. These include reaching peak carbon emissions before 2030 and becoming carbon neutral before 2060.

Modular reactors like Linglong-1 could be useful in many countries, especially those who need clean and stable energy sources without the high cost and size of traditional nuclear plants. The smaller design will also make building and operating reactors easier in areas with less infrastructure.

Once completed, Linglong-1 will become a key part of China’s energy system. It will demonstrate how nuclear technology can be used safely and efficiently to fight climate change. It may also assist Chinato become a major exporter of SMR technology in the future.

China National Nuclear Corporation

The U.S. Department of Energy (DoE) is expediting the construction of the world’s first two microreactor test beds. Microreactors can provide one to fifty-megawatts of reliable power.

Named Demonstration of Microreactor Experiments (DOME) and Laboratory for Operation and Testing in the United States (LOTUS), the two test beds will allow reactor developers to test their fueled microreactor experiments quickly, safely, and cost-effectively by leveraging existing infrastructure at the Idaho National Laboratory (INL). The DoE has granted priority rating authorization to Idaho National Laboratory (INL).

The new rating system is based on recent actions by the DoE to streamline construction projects across the national laboratories to restore energy dominance and help spur U.S. innovation.

Rian Bahran is the DoE Deputy Assistant Secretary for Nuclear Reactors. He said, “As President Trump and Secretary Wright have directed, we are coordinating across the federal government and using every tool at our disposal to unleash American energy abundance and dominance. The priority rating under the Defense Production Act for these reactor test beds at Idaho National Laboratory will be an important instrument ensuring we start the American nuclear renaissance now.”

In early May of this year, INL submitted a special priorities request to DoE to receive priority rating authorization on contracts and orders related to the construction of the DOME and LOTUS microreactor test beds.

INL explained that microreactors are small, factory-built nuclear reactors that can provide between one and fifty megawatts of reliable power to remote locations, military bases, and commercial operations.

The DOME and LOTUS test beds are operated by the DoE’s National Reactor Innovation Center (NRIC) to accelerate the demonstration and deployment of advanced microreactor systems.

According to an INL press release, the DOME test bed is repurposing the lab’s Experimental Breeder Reactor-II containment structure to lower the risk of developing microreactor designs capable of producing twenty megawatts or less of thermal energy.

The LOTUS test bed is expected to be housed in the INL’s former Zero Power Physics Reactor facility. The test bed will be part of the world’s first fast-spectrum, salt-fueled reactor test led by Southern Company and TerraPower.

Brad Tomer is the Director of NRIC. He said, “This priority rating will significantly reduce the time it will take to secure the components and services we need to complete the test beds and help microreactor developers stay on their aggressive schedules.”.

DOME is expected to host experimental reactors up to twenty megawatts of thermal energy using high-assay low-enriched uranium (HALEU) in an environment that safely supports nuclear systems going critical for the first time. An end-to-end reactor testing ecosystem will support reactor developers from the initial design through testing and decommissioning.

Currently, microreactor developers can submit applications to schedule their microreactor experiments in the NRIC DOME test bed facility.

The U.S. DoE has released an application guide to assist reactor developers through the submission process. The sequencing of reactor experiments will be based on several criteria. These include technology readiness, fuel type and availability, regulatory approval plan, and the developer’s capabilities.

Idaho National Laboratory

NuScale Power Corporation is a publicly traded American company that designs and markets small modular reactors (SMRs). It is headquartered in Tigard, Oregon.

The U.S. Nuclear Regulatory Commission on Thursday approved NuScale Power’s design for seventy-seven megawatt reactors called VOYGR, clearing a hurdle for the company as it seeks to be the first company to build a U.S. small modular reactor (SMR).

NuScale sought approval for the seventy-seven megawatt design to improve economics and performance of its planned small modular reactors (SMRs), after having originally received NRC approval in 2020 for a fifty megawatt reactor design.

SMRs are designed to be constructed in factories with relatively easily replicated parts instead of onsite like conventional nuclear power plants. Backers say these reactors will be safer to operate, their uranium cycles will be more resistant to access from militants seeking to obtain fissile materials, and their modular nature will reduce costs for multiple plants.

SMR critics say that they will be more expensive to operate than conventional nuclear reactors and they will continue to produce radioactive waste for which the U.S. currently has no permanent repository.

NuScale is the only U.S. company with an approved SMR design, but reaching the point of building a plant has been difficult. In 2023 NuScale cancelled its first project with a Utah municipal power group, despite a U.S. government promise of one billion three hundred and five million dollars in funding over ten years for the plant, known as the Carbon Free Power Project. As costs rose for the project rose, several towns had pulled out of the project.

John Hopkins is NuScale’s president and chief executive. He said that Thursday’s approval, which came two months earlier than had been expected, permits the company to construct and operate a plant.

Hopkins added, “We now have an American technology that is near-term deployable.”. As many as twelve of the seventy-seven reactors can be put together in a plant which would be about the size of a typical conventional reactor.

Hopkins said that the company could have an SMR in operation by the end of the decade if a customer moves quickly to submit an order. “It’s really in the customer’s hands,” he remarked. NuScale shares were down four percent at thirty-four dollars in afternoon trade.

Interest in nuclear power has spiked as U.S. power demand has risen for the first time in two decades on the boom in so-called hyper-scalers building data centers needed for artificial intelligence.

Last week President Donald Trump signed four executive orders to overhaul the NRC, including the reduction of staffing levels in some offices. The executive orders also directed the Energy and Defense departments to work together to construct nuclear plants on federal lands.

The orders did not provide any new public funding but could open the way for financing from the Loan Programs Office.

Hopkins said NuScale is in negotiations to build SMRs with five “tier one hyper-scalers that we have non-disclosure agreements with”. He did not identify with the customers placing the orders.

NuScale