Researchers at Oak Ridge National Laboratory (ORNL) have added real-time visual tracking to their nuclear accident simulation equipment. By installing a camera window into a specialized furnace wall, scientists use digital image correlation to measure fuel cladding deformation as it happens. 

This is the first time researchers have captured these physical changes visually during a simulated loss-of-coolant accident (LOCA).

The severe accident testing station (SATS) at ORNL is the only domestic facility that can run these simulated failures on commercial, radioactive fuel rods. The protective outer layer, known as cladding, holds the nuclear fuel. Gathering precise data on this setup helps the nuclear industry reduce regulatory uncertainty.

This testing supports a broader national effort to approve accident-tolerant and high-burnup fuels, which allow commercial reactors to run longer and generate more power without raising costs.

Grid demand and regulatory approvals

Data centers and artificial intelligence systems are increasing the demand for steady electricity. Rather than building new facilities, power companies want to optimize current light-water reactors. This process, called a power uprate, increases electricity output by running fuel at higher temperatures and adjusting operational margins.

“A power uprate means increasing a plant’s electrical output by optimizing its operational margins — and removing overly conservative guidelines where appropriate — so that the fuel can operate at higher power levels,” said Nathan Capps, senior R&D staff in the Fuel Cladding and Core Internals group.

When utilities combine power uprates with extended fuel lifespans, they generate more energy from the same resources. To date, the Nuclear Regulatory Commission (NRC) has approved 171 power uprates. 

This has added power equivalent to eight new reactors to the U.S. grid without new construction. However, utilities must submit experimental data proving safety before the NRC approves these operational changes.

The simulation process

To replicate an accident where cooling water drops out of a reactor core, ORNL scientists follow a specific sequence. A fuel rod segment between 1 and 12 inches long is placed inside a quartz tube and centered with spacer disks. Next, researchers pressurize the inside of the segment to replicate the internal stress of a full-length active rod. 

An infrared furnace then heats the sample to a target temperature at a controlled rate. Finally, water floods the chamber to cool the segment back to room temperature. The entire process takes two to three minutes.

SATS uses two stations to complete this research. The first operates in a standard lab to map out experiments and test non-radioactive materials. The second station sits inside a heavily shielded hot cell to run identical parameters on radioactive commercial fuel. 

Beyond structural changes, the system tracks how trapped gases escape during temperature spikes and how fuel moves during a failure.

Industry applications

Fuel manufacturers use ORNL’s data to create safety reports for regulatory review. Over the past four years, ORNL has completed 16 LOCA tests alongside companies like Southern Nuclear, Constellation, Westinghouse, Framatome, and Global Nuclear Fuel. 

The laboratory plans to double its testing volume to help utilities meet rising grid demands.

The US Department of Energy (DOE) has officially cleared the preconceptual design and technology development roadmap for Xcimer Energy’s fusion power plant architecture, named Athena.

This regulatory clearance follows an intense evaluation of a 724-page proposal that covered system engineering, safety protocols, economic projections, and environmental impacts.

The government’s sign-off concludes Xcimer’s initial 18-month budget cycle within the federal Milestone-Based Fusion Development Program, an initiative intended to advance commercial fusion through public-private partnerships.

This administrative milestone closely follows the activation of Xcimer’s prototype laser system, Phoenix, last week. Located inside a 74,000-square-foot facility in Denver, Phoenix is currently the largest operational private laser system globally.

“Phoenix is a proof of concept for an unconventional fusion architecture: a krypton fluoride (KrF) excimer laser using Stimulated Brillouin Scattering (SBS) to compress a microsecond-long pulse into the nanosecond timescales fusion requires,” said the company in a press release.

Viability of long-term power generation

While historical laboratory efforts, such as those at the National Ignition Facility, proved that laser fusion physics could surpass the scientific breakeven point, Xcimer’s program focuses on the financial and mechanical viability of long-term power generation.

The Athena platform serves as the blueprint for a projected fleet of commercial plants designed to operate continuously for multiple decades.

A central challenge in fusion engineering is protecting reactor structures from degrading under constant radiation. Xcimer intends to address this by using a moving curtain of molten salt inside the reactor chamber instead of a static solid wall.

According to Susana Reyes, Vice President for Chamber and Plant Design, this liquid barrier absorbs neutron flux, generates tritium fuel, and transfers heat while constantly renewing itself.

“We are designing Athena to run continuously at a repetition rate of up to 1 Hz, and the use of a liquid wall chamber maximizes availability by protecting the solid structures from the fusion reaction emissions over the entire plant lifetime,” said Reyes.

Establishing scalable industrial manufacturing

Company officials state that the primary obstacle to fusion energy is no longer validating the underlying science, but establishing scalable industrial manufacturing.

Conner Galloway, CEO and Chief Science Officer, noted that the DOE’s review confirms the mechanical viability of the Athena framework and establishes a structured pathway toward commercial deployment.

“The question facing laser fusion is no longer whether the physics works,” said Galloway. “The question is how fast we can industrialize it.

Xcimer’s engineering targets include limiting laser manufacturing expenses to less than $100 per joule to ensure competitive energy pricing. Following the federal approval of the Athena roadmap, the Denver-based firm plans to transition into its next operational phase.

The upcoming schedule requires Xcimer to begin full-scale subsystem testing, complete engineering validations, and finalize the technical preparations necessary for a comprehensive, integrated pilot plant demonstration.

“We designed Athena around that property from day one, and it shapes everything: the materials choices, the thermal management, the maintenance philosophy, the economics. And Xcimer’s laser architecture uniquely enables this design,” concluded Reyes.

Energy technology firm AMPERA has confirmed that its new modular, supercritical nuclear systems will operate on thorium obtained from Australian suppliers. The raw material will be managed and processed through an internal supply chain established by the business.

“Our strategy is to secure thorium directly at the source and vertically integrate the entire fuel value chain, from mineral supply through advanced fuel production,” said AMPERA Founder and CEO Brian Matthews.

“Thorium offers a compelling combination of abundance, energy potential, economics, and safety, making it an ideal fuel for AMPERA’s advanced microreactors and a promising resource for the broader nuclear industry.”

To manage the import logistics, the business launched an overseas branch named Ampera Australia earlier this year. This expansion builds upon a bilateral critical minerals agreement signed by the United States and Australian governments late last year, which sets guidelines for the extraction and processing of rare-earth elements.

Domestic production strategy

Following the launch of its primary office in Florida this past April, the organization intends to set up a secondary facility within the state dedicated to fuel production.

The manufacturing plant will focus on turning the raw material into tri-structural isotropic (TRISO) fuel kernels. This fabrication process involves proprietary liquid jetting methods and additive manufacturing techniques. The company has filed more than 60 patents and established trade secrets to safeguard these technical designs.

“Thorium is the future for ultra-safe, clean power production,” Matthews added. “By producing TRISO thorium kernels in the United States, we can ensure ample access to the needed fuel supply as we scale up and also minimize price volatility risk.”

Domestic production is intended to shield the company’s manufacturing pipeline from international market shifts. Internalizing the assembly phase ensures that the business maintains a predictable volume of fuel as it expands its hardware assembly lines.

Technical profile of thorium fuel

Using element 90 presents alternative mechanics compared to standard uranium-based nuclear designs. The material is widespread, with crustal reserves measuring approximately three times larger than those of uranium.

When utilized in advanced cycles, it demonstrates a higher fuel utilization rate, which means a larger percentage of the material undergoes fission rather than turning into heavy waste. The material starts out as weakly radioactive and fertile, meaning it must absorb a neutron to become fissile reactor fuel.

Additionally, the chemical byproducts are less suited for weapons production, and the cycle yields a smaller volume of long-lived transuranic elements compared to typical uranium-plutonium processes. 

Documentation from the International Atomic Energy Agency (IAEA) indicates that these fuel cycles could support global electrical infrastructure requirements over a long time horizon.

Generating decades of electricity

The firm’s compact units use a subcritical design that will be permanently enclosed during initial assembly. These modules are intended to generate electricity continuously for three decades without needing a replacement fuel core.

“Through its proprietary TRISO fuel platform, neutron-source technology and advanced additive manufacturing, AMPERA delivers scalable, factory-built, rapidly deployable, emission-free power for data centers, defense, industrial and maritime applications,” concluded the company in a press release.

Thea Energy will develop a virtual model of its planned fusion power plant using software engineering and computation tools. The enterprise aims to replicate its upcoming “Helios” facility as a digital twin, which allows engineers to simulate the plant’s operational variables before construction begins.

To execute this project, the firm is working with technology companies NVIDIA and Synopsys, alongside two federal entities: Argonne National Laboratory and Princeton Plasma Physics Laboratory.

The initiative connects to the US Department of Energy’s Genesis Mission, an agency program that applies data analytics to accelerate projects outlined in the national Fusion Science and Technology Roadmap. 

By simulating physical systems through software, the team expects to lower the capital requirements typically needed for hardware-based exploratory testing. The engineering timeline targets the delivery of grid-ready baseload electricity by 2035.

Distribution of technical responsibilities

The participating organizations provide distinct computational and physical datasets to build the overarching virtual architecture.

NVIDIA provides its Omniverse computing infrastructure to ingest Thea Energy’s baseline code. This framework allows engineers to view three-dimensional operational data and track potential design adjustments simultaneously.

Synopsys is responsible for integrating structural data into a multiphysics software environment. Its primary objective is to analyze the performance of the plant’s breeding blanket, a component that absorbs thermal energy from the fusion core and provides a radiation barrier for the surrounding magnetic systems.

Argonne National Laboratory delivers specialized data on particle interactions and neutronics. By feeding this data into the virtual model, the lab helps train software algorithms to predict how the physical blanket components will handle high-energy particle bombardment.

Princeton Plasma Physics Laboratory supplies numerical codes that map plasma behavior. These calculations provide the digital twin with the rules necessary to model highly turbulent ionized gases under elevated temperature and pressure conditions.

Mechanical design shift

Traditional stellarators require complex, curved three-dimensional magnetic coils to contain plasma. Thea Energy alters this approach by utilizing flat, repeatable planar magnetic coils arranged in a specific geometry. 

Because flat magnets are easier to manufacture, the physical complexity of plasma containment is transferred to computer software.

The control software regulates the magnetic fields dynamically. This configuration permits the system to adjust for physical deformation or material degradation during continuous operations without requiring manual mechanical interventions.

Development sequence

The road map for deployment consists of two primary hardware systems. The initial system, named Eos, serves as a large-scale prototype designed to achieve steady-state fusion and test structural integrity under real operational loads.

Following the validation of the prototype, the company will build the Helios facility, which will operate as a commercial power station in the 2030s. The digital twin framework is designed to function as an active feedback loop between these two systems. 

Engineers will apply data derived from the virtual Helios model to optimize the engineering components of the Eos prototype during its active testing phases.

A research team at the Idaho National Laboratory (INL) recently documented the electronic behavior of a specific plutonium compound, shifting the focus of modern actinide research toward quantum mechanics.

According to their published paper, the compound plutonium hexaboride (PuB6) functions as a topological Kondo insulator. “Plutonium hexaboride gives us a rare opportunity to see how strong correlations and topology work together in actinide materials,” said INL scientist Krzysztof Gofryk, who led the study.

This precise atomic state provides alternative structural data for an element that has historically resisted complete physical classification since its initial synthesis eighty-six years ago.

Giving physicists a controlled baseline

While plutonium remains a primary component within nuclear security frameworks and commercial reactor fuel cycles, its internal electron dynamics have consistently proven difficult to map. The state observed in the PuB6 compound gives physicists a controlled baseline to study the underlying physics governing the heaviest elements of the periodic table.

The classification of PuB6 as a topological Kondo insulator indicates a departure from standard electrical behaviors. Standard substances are categorized by their ability to either transmit an electric current or resist it entirely. 

Topological insulators alter this distribution by acting as barriers to electricity within their bulk core while maintaining open conductive pathways along their outer perimeter. 

“The surface conductivity of topological insulators is unusually strong; it can’t be easily disrupted by impurities or physical defects,” said the researchers in a press release.

Identifying a specific quantum phenomenon

The term “Kondo” identifies a specific quantum phenomenon where individual electrons experience strong mutual repulsion. These close-range interactions cause the particles to act collectively rather than as independent units, generating physical properties that cannot be extrapolated by looking at single, isolated atoms. 

“Plutonium is a striking example,” added the researchers. “It contains 5f electrons, which are especially prone to these intense interactions, making it one of the most dramatic and complex materials known.”

By testing the hexaboride compound, the laboratory team recorded how these strong electron correlations coordinate with the geometric boundaries of the material’s surface.

Because actinide elements are highly radioactive, physical experimentation requires specialized safety protocols. The laboratory used a plasma focused ion beam to isolate microscopic sections of the plutonium compound, allowing researchers to place the material into ultra-low temperature environments. 

Minimizing thermal energy removes ambient atomic vibrations, allowing the team to measure pure quantum mechanics without heat interference.

Validating the metrics

“These advanced preparation techniques allow us to study plutonium at very low temperatures,” explained INL researcher Daniel Murray.

To validate the metrics, the researchers worked alongside theoretical physicists at Columbia University, matching the physical measurements against numerical computer models. 

The resilient currents found on the surface of topological materials offer a potential pathway for building stable processing units in quantum computers and developing high-precision magnetic sensors.

“On the quantum side, the research has potential applications in quantum computing, advanced sensing and frontier technologies that could fundamentally reshape how researchers model nuclear systems and materials,” concluded the press release.