Category: Academic Reportage

Source: The Conversation – USA (3) – By Michael Bruening, Professor of History, Missouri University of Science and Technology

Ideological division was tearing the country apart. Factions denounced each other as unpatriotic and evil. There were attempted kidnappings and assassinations of political figures. Public monuments and art were desecrated all over the country.

This was France in the middle of the 16th century. The divisions were rooted in religion.

The Protestant minority denounced Catholics as “superstitious idolaters,” while the Catholics condemned Protestants as “seditious heretics.” In 1560, Protestant conspirators attempted to kidnap the young King Francis II, hoping to replace his zealous Catholic regents with ones more sympathetic to the Protestant cause.

Two years later, the country collapsed into civil war. The French Wars of Religion had begun – and would convulse the country for the next 36 years.

I am a historian of the Reformation who writes about the opponents of John Calvin, a leading Protestant theologian who influenced Reformed Christians, Presbyterians, Puritans and other denominations for centuries. One of the most significant of Calvin’s rivals was the humanist Sebastian Castellio, whom he had worked with in Geneva before a bitter falling out over theology.

Soon after the first war in France broke out, Castellio penned a treatise that was far ahead of its time. Rather than join in the bitter denunciations raging between Protestants and Catholics, Castellio condemned intolerance itself.

He identified the main problem as both sides’ efforts to “force consciences” – to compel people to believe things they did not believe. In my view, that advice from nearly five centuries ago has much to say to the world today.

Foreseeing the carnage

Castellio rose to prominence in 1554 when he condemned the execution of Michael Servetus, a medical doctor and theologian convicted of heresy. Servetus had rejected the standard Christian belief in the Trinity, which holds that the Father, Son and Holy Spirit are three persons in one God.

Already condemned by the Catholic Inquisition in France, Servetus was passing through Geneva when Calvin urged his arrest and advocated for his execution. Servetus was burned alive at the stake.

Castellio condemned the execution in a remarkable book titled “Concerning Heretics: Whether They are to be Persecuted and How They are to be Treated.” In it, Castellio questioned the very notion of heresy: “After a careful investigation into the meaning of the term heretic, I can discover no more than this, that we regard those as heretics with whom we disagree.”

In the process, he laid the intellectual foundations for religious toleration that would come to dominate Western political philosophy during the Enlightenment.

But it took centuries for religious toleration to take hold.

In the meantime, Europe became embroiled in a series of religious wars. Most were civil wars between Protestants and Catholics, including the French Wars of Religion, a series of conflicts from 1562 to 1598. These included one of the most horrific events of the 16th century: the St. Bartholomew’s Day Massacre of 1572, when thousands of Protestants were slain in a nationwide bloodbath.

Castellio had seen the carnage coming: “So much blood will flow,” he had warned in a treatise 10 years earlier, “that its loss will be irremediable.”

Remembering the Golden Rule

Castellio’s 1562 book, “Advice to a Desolate France,” was a rarity in the 16th century, for it sought compromise and the middle ground rather than the religious extremes.

With an extraordinarily modern sensibility, he decided to use the terms each side preferred for themselves, rather than the negative epithets used by their opponents.

“I shall call them what they call themselves,” he explained, “in order not to offend them.” Hence, he used “Catholics” rather than “Papists” and “evangelicals” rather than “Huguenots.”

Castellio pulled no punches. To the Catholics, referring to decades of Protestant persecution in France, he said: “Recall how you have treated the evangelicals. You have pursued and imprisoned them … and then you have roasted them alive at a slow fire to prolong their torture. And for what crime? Because they did not believe in the pope, the Mass, and purgatory. … Is that a good and just cause for burning men alive?”

To the Protestants, he complained, “You are forcing them against their consciences to attend your sermons, and what is worse, you are forcing some to take up arms against their own brothers.” He noted that they were using three “remedies” for healing the church, “namely bloodshed, the forcing of consciences, and the condemning and regarding as unfaithful of those who are not entirely in agreement with your doctrine.”

In short, Castellio accused both sides of ignoring the Golden Rule: “Do not do unto others what you would not want them to do unto you,” he wrote. “This is a rule so true, so just, so natural, and so written by the finger of God in the hearts of all,” he asserted, that none can deny it.

Both sides were trying to promote their vision of true religion, Castellio said, but both were going about it the wrong way. In particular, he warned against trying to justify evil behavior by appealing to its possible effects: “One should not do wrong in order that good may result from it.”

In another essay, he made the same point to argue against torture, writing that “Evil must not be done in order to pursue the good.” Castellio was the anti-Machiavelli; for him, the ends did not justify the means.

Force doesn’t work

Finally, “Advice to a Desolate France” argued that forcing people to your own way of thinking never works: “We manifestly see that those who are forced to accept the Christian religion, whether they are a people or individuals, never make good Christians.”

Americans, I believe, would do well to bear Castellio’s words in mind today. The country’s two dominant political parties have become increasingly polarized. Students are reluctant to speak out on controversial topics for fear of “saying the wrong thing.” Americans increasingly think in binary terms of good and evil, friends and enemies.

In the 16th century, Christians failed to heed Castellio’s advice and continued to kill each other over differences of belief for another hundred years. It would be wise to apply his ideas to today’s bitter divisions.

Michael Bruening does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

– ref. Why one 16th-century theologian’s advice for a bitterly divided nation holds true today – https://theconversation.com/why-one-16th-century-theologians-advice-for-a-bitterly-divided-nation-holds-true-today-266457

Source: The Conversation – USA – By Mojtaba Akhavan-Tafti, Associate Research Scientist, University of Michigan

The rapid expansion of artificial intelligence and cloud services has led to a massive demand for computing power. The surge has strained data infrastructure, which requires lots of electricity to operate. A single, medium-sized data center here on Earth can consume enough electricity to power about 16,500 homes, with even larger facilities using as much as a small city.

Over the past few years, tech leaders have increasingly advocated for space-based AI infrastructure as a way to address the power requirements of data centers.

In space, sunshine – which solar panels can convert into electricity – is abundant and reliable. On Nov. 4, 2025, Google unveiled Project Suncatcher, a bold proposal to launch an 81-satellite constellation into low Earth orbit. It plans to use the constellation to harvest sunlight to power the next generation of AI data centers in space. So, instead of beaming power back to Earth, the constellation would beam data back to Earth.

For example, if you asked a chatbot how to bake sourdough bread, instead of firing up a data center in Virginia to craft a response, your query would be beamed up to the constellation in space, processed by chips running purely on solar energy, and the recipe sent back down to your device. Doing so would mean leaving the substantial heat generated behind in the cold vacuum of space.

As a technology entrepreneur, I applaud Google’s ambitious plan. But as a space scientist, I predict that the company will soon have to reckon with a growing problem: space debris.

The mathematics of disaster

Space debris – the collection of defunct human-made objects in Earth’s orbit – is already affecting space agencies, companies and astronauts. This debris includes large pieces, such as spent rocket stages and dead satellites, as well as tiny flecks of paint and other fragments from discontinued satellites.

Space debris travels at hypersonic speeds of approximately 17,500 miles per hour (28,000 km/h) in low Earth orbit. At this speed, colliding with a piece of debris the size of a blueberry would feel like being hit by a falling anvil.

Satellite breakups and anti-satellite tests have created an alarming amount of debris, a crisis now exacerbated by the rapid expansion of commercial constellations such as SpaceX’s Starlink. The Starlink network has more than 7,500 satellites, which provide global high-speed internet.

The U.S. Space Force actively tracks over 40,000 objects larger than a softball using ground-based radar and optical telescopes. However, this number represents less than 1% of the lethal objects in orbit. The majority are too small for these telescopes to reliably identify and track.

In November 2025, three Chinese astronauts aboard the Tiangong space station were forced to delay their return to Earth because their capsule had been struck by a piece of space debris. Back in 2018, a similar incident on the International Space Station challenged relations between the United States and Russia, as Russian media speculated that a NASA astronaut may have deliberately sabotaged the station.

The orbital shell Google’s project targets – a Sun-synchronous orbit approximately 400 miles (650 kilometers) above Earth – is a prime location for uninterrupted solar energy. At this orbit, the spacecraft’s solar arrays will always be in direct sunshine, where they can generate electricity to power the onboard AI payload. But for this reason, Sun-synchronous orbit is also the single most congested highway in low Earth orbit, and objects in this orbit are the most likely to collide with other satellites or debris.

As new objects arrive and existing objects break apart, low Earth orbit could approach Kessler syndrome. In this theory, once the number of objects in low Earth orbit exceeds a critical threshold, collisions between objects generate a cascade of new debris. Eventually, this cascade of collisions could render certain orbits entirely unusable.

Implications for Project Suncatcher

Project Suncatcher proposes a cluster of satellites carrying large solar panels. They would fly with a radius of just one kilometer, each node spaced less than 200 meters apart. To put that in perspective, imagine a racetrack roughly the size of the Daytona International Speedway, where 81 cars race at 17,500 miles per hour – while separated by gaps about the distance you need to safely brake on the highway.

This ultradense formation is necessary for the satellites to transmit data to each other. The constellation splits complex AI workloads across all its 81 units, enabling them to “think” and process data simultaneously as a single, massive, distributed brain. Google is partnering with a space company to launch two prototype satellites by early 2027 to validate the hardware.

But in the vacuum of space, flying in formation is a constant battle against physics. While the atmosphere in low Earth orbit is incredibly thin, it is not empty. Sparse air particles create orbital drag on satellites – this force pushes against the spacecraft, slowing it down and forcing it to drop in altitude. Satellites with large surface areas have more issues with drag, as they can act like a sail catching the wind.

To add to this complexity, streams of particles and magnetic fields from the Sun – known as space weather – can cause the density of air particles in low Earth orbit to fluctuate in unpredictable ways. These fluctuations directly affect orbital drag.

When satellites are spaced less than 200 meters apart, the margin for error evaporates. A single impact could not only destroy one satellite but send it blasting into its neighbors, triggering a cascade that could wipe out the entire cluster and randomly scatter millions of new pieces of debris into an orbit that is already a minefield.

The importance of active avoidance

To prevent crashes and cascades, satellite companies could adopt a leave no trace standard, which means designing satellites that do not fragment, release debris or endanger their neighbors, and that can be safely removed from orbit. For a constellation as dense and intricate as Suncatcher, meeting this standard might require equipping the satellites with “reflexes” that autonomously detect and dance through a debris field. Suncatcher’s current design doesn’t include these active avoidance capabilities.

In the first six months of 2025 alone, SpaceX’s Starlink constellation performed a staggering 144,404 collision-avoidance maneuvers to dodge debris and other spacecraft. Similarly, Suncatcher would likely encounter debris larger than a grain of sand every five seconds.

Today’s object-tracking infrastructure is generally limited to debris larger than a softball, leaving millions of smaller debris pieces effectively invisible to satellite operators. Future constellations will need an onboard detection system that can actively spot these smaller threats and maneuver the satellite autonomously in real time.

Equipping Suncatcher with active collision avoidance capabilities would be an engineering feat. Because of the tight spacing, the constellation would need to respond as a single entity. Satellites would need to reposition in concert, similar to a synchronized flock of birds. Each satellite would need to react to the slightest shift of its neighbor.

Paying rent for the orbit

Technological solutions, however, can go only so far. In September 2022, the Federal Communications Commission created a rule requiring satellite operators to remove their spacecraft from orbit within five years of the mission’s completion. This typically involves a controlled de-orbit maneuver. Operators must now reserve enough fuel to fire the thrusters at the end of the mission to lower the satellite’s altitude, until atmospheric drag takes over and the spacecraft burns up in the atmosphere.

However, the rule does not address the debris already in space, nor any future debris, from accidents or mishaps. To tackle these issues, some policymakers have proposed a use-tax for space debris removal.

A use-tax or orbital-use fee would charge satellite operators a levy based on the orbital stress their constellation imposes, much like larger or heavier vehicles paying greater fees to use public roads. These funds would finance active debris removal missions, which capture and remove the most dangerous pieces of junk.

Avoiding collisions is a temporary technical fix, not a long-term solution to the space debris problem. As some companies look to space as a new home for data centers, and others continue to send satellite constellations into orbit, new policies and active debris removal programs can help keep low Earth orbit open for business.

Mojtaba Akhavan-Tafti receives funding from NASA and Intelligence Advanced Research Projects Activity (IARPA). He teaches space systems engineering and mission design and management at the University of Michigan’s College of Engineering.

– ref. Google’s proposed data center in orbit will face issues with space debris in an already crowded orbit – https://theconversation.com/googles-proposed-data-center-in-orbit-will-face-issues-with-space-debris-in-an-already-crowded-orbit-270410

Source: The Conversation – USA – By Melinda Haas, Assistant Professor of International Affairs, University of Pittsburgh

A largely overlooked directive issued by the Trump administration marks a major shift in U.S. counterterrorism policy, one that threatens bedrock free speech rights enshrined in the Bill of Rights.

National Security Presidential Memorandum/NSPM-7, issued on Sept. 25, 2025, is a presidential directive that for the first time appears to authorize preemptive law enforcement measures against Americans based not on whether they are planning to commit violence but for their political or ideological beliefs.

You’ve probably heard a lot about President Donald Trump’s many executive orders. But as an international relations scholar who has studied U.S. foreign policy decision-making and national security legislation, I recognize that presidents can take several types of executive actions without legislative involvement: executive orders, memoranda and proclamations.

This structure allows the president to direct law enforcement and national security agencies, with little opportunity for congressional oversight.

This seventh national security memorandum from the Trump White House pushes the limits of presidential authority by targeting individuals and groups as potential domestic terrorists based on their beliefs rather than their actions.

The memorandum represents a profound shift in U.S. counterterrorism policy, one that risks undermining foundational American commitments to free speech and association.

Presidential national security powers

Executive memoranda instruct government officials and agencies by delegating tasks and directing agency actions.

They can, for example, order a department to prepare reports, implement new policies, coordinate interagency efforts or review existing programs to align with the administration’s priorities.

Unlike executive orders, they are not required to be published. When these memoranda, like NSPM-7, relate to national security and military and foreign policy, they are called national security directives, although the specific name of these directives changes with each administration.

Many of these directives are classified. They may not be declassified, if at all, until years or decades after the end of the administration that issued them.

The stated purpose of NSPM-7 is to counter domestic terrorism and organized political violence, focusing mainly on perceived threats from the political left. The memorandum identifies “anti-Christian,” “anti-capitalism” or “anti-American” views as potential indicators that a group or person will commit domestic terrorism.

The memorandum claims that political violence originates with “anti-fascist” groups that hold the following views: “support for the overthrow of the United States Government; extremism on migration, race, and gender; and hostility towards those who hold traditional American views on family, religion, and morality.”

The strategy laid out in NSPM-7 includes preemptive measures to disrupt groups before they engage in violent political acts. For example, multiagency task forces are empowered to investigate potential federal crimes related to radicalization, as well as the funders of those potential crimes.

‘Domestic terrorist organizations’

The memorandum directs the Department of Justice to focus the resources of the FBI’s approximately 200 Joint Terrorism Task Forces on investigating “acts of recruiting or radicalizing persons” for the purpose of “political violence, terrorism, or conspiracy against rights; and the violent deprivation of any citizen’s rights.”

NSPM-7 also allows the attorney general to propose groups for designation as “domestic terrorist organizations.” That includes groups that engage in the following behaviors: “organized doxing campaigns, swatting, rioting, looting, trespass, assault, destruction of property, threats of violence, and civil disorder.”

Existing laws allow the secretary of state to designate groups as “foreign terrorist organizations” that are then subject to financial sanctions.

But these laws do not permit the president to label domestic groups this way.

Defining terrorism

NSPM-7 marks a major conceptual shift in U.S. counterterrorism policy. Its focus on domestic terrorism significantly departs from historical approaches that primarily targeted foreign threats.

Earlier presidential directives largely defined terrorism as a foreign threat to be countered through military power, diplomacy and international cooperation.

Since Ronald Reagan’s presidency, the U.S. government had treated terrorism as a global menace to democratic institutions, emphasizing protection of citizens and allies abroad. By moving away from a traditional law enforcement framework and recasting terrorism as an act of war, the Reagan administration situated the issue within the broader realm of Cold War geopolitics and military advantage.

In the 1990s, the Clinton administration reframed terrorism as both a foreign policy and domestic security challenge, particularly after high-profile attacks such as the 1993 World Trade Center bombing and the 1995 Oklahoma City bombing. Clinton’s policy highlighted the dangers of transnational networks and the need to defend critical infrastructure.

After the 9/11 attacks, the Bush administration fused counterterrorism with national defense. The Bush-initiated global war on terrorism expanded the concept of who constituted a threat to include countries that harbored or aided terrorist organizations.

The Obama administration tried to narrow and regulate those powers by embedding counterterrorism within a system of legal rules and procedures. The key question, according to the declassified guidance, was whether the targeted individuals “pose a continuing, imminent threat to U.S. persons.”

This standard was not focused on ideology but rather on tactical considerations, such as the feasibility of capture and continued threat to U.S. interests.

For example, the lethal drone strike on al-Qaida propagandist Anwar al-Awlaki in 2011 was justified on the basis that he was actively involved in plotting attacks and remained unreachable for capture.

During the first Trump presidency, executive orders were used to change counterterrorism policy, most notably through several iterations of a “travel ban” that attempted to restrict immigration from terror-prone countries such as Iraq, Iran, Somalia, Syria and Yemen.

The Biden administration redirected attention toward preventing catastrophic threats, especially from weapons of mass destruction in the hands of groups or individuals outside of governments, such as terrorist organizations.

First Amendment rights at risk

There is no single official definition of terrorism in U.S. law.

Instead, laws use different definitions based on their purpose, whether criminal law or laws relating to intelligence collection or civil liability.

Definitions in all those areas typically focus on identifying violent or dangerous acts done with the intent to intimidate or coerce civilians or influence government policy.

But more than redefining terrorism, NSPM-7 reorients the machinery of national security toward the policing of belief.

The First Amendment generally prevents the government from punishing people for unpopular opinions. It also protects the ability for people to associate to advance public and private ideas in pursuit of political, economic, religious or cultural goals.

The directive’s emphasis on ideological orientations – “anti-Christianity,” “anti-capitalism” and “anti-American” views – as indicators of domestic terrorism potentially jeopardizes First Amendment rights.

Thirty-one members of Congress sent a letter to Trump expressing “serious concerns” about NSPM-7, warning that it poses “serious constitutional, statutory and civil liberties risks, especially if used to target political dissent, protest or ideological speech.”

As the ACLU warns, any definition of terrorism that includes ideological components risks criminalizing people or groups based on belief rather than based on violence or other criminal conduct.

Congress has declined to create a domestic complement to the foreign terrorist designation in large part because of the potential for impinging on First Amendment–protected association and speech.

But I fear that chilling speech may be the point.

Silencing dissent

NSPM-7 does not authorize new actions in the legal and institutional framework for counterterrorism. It does not criminalize previously legal conduct.

Rather, it states that the Trump administration’s investigative focus will be around the identity and ideology of supposed perpetrators. Prioritizing investigations into this broad swath of ideologies serves to instill fear, silencing anti-fascist and other messages in opposition to the Trump administration.

Law professor Steve Vladeck frames this chill as “obeying in advance,” in which organizations self-censor rather than risk investigation, prosecution or defending against the “domestic terrorist” label.

Although left-wing violence has risen in the past decade, empirical evidence proves that this violence remains at very low absolute levels, well below historical levels of right-wing or jihadist violence.

In fact, most domestic terrorists in the U.S. are politically on the right, and right-wing attacks account for the vast majority of fatalities from domestic terrorism.

Yet NSPM-7 focuses disproportionately on left-wing ideologies. NSPM-7 departs from prior U.S. counterterrorism frameworks by prioritizing the suppression of ideologically motivated dissent, even in the absence of concrete evidence of violent intent.

Melinda Haas does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

– ref. Labeling dissent as terrorism: New US domestic terrorism priorities raise constitutional alarms – https://theconversation.com/labeling-dissent-as-terrorism-new-us-domestic-terrorism-priorities-raise-constitutional-alarms-269161

Source: The Conversation – USA – By Emilee Rader, Professor of Information, University of Wisconsin-Madison

If you use a mobile phone with location services turned on, it is likely that data about where you live and work, where you shop for groceries, where you go to church and see your doctor, and where you traveled to over the holidays is up for sale. And U.S. Immigration and Customs Enforcement is one of the customers.

The U.S. government doesn’t need to collect data about people’s locations itself, because your mobile phone is already doing it. While location data is sometimes collected as part of a mobile phone app’s intended use, like for navigation or to get a weather forecast, more often locations are collected invisibly in the background.

I am a privacy researcher who studies how people understand and make decisions about data that is collected about them, and I research new ways to help consumers get back some control over their privacy. Unfortunately, once you give an app or webpage permission to collect location data, you no longer have control over how the data is used and shared, including who the data is shared with or sold to.

Why mobile phones collect location data

Mobile phones collect location data for two reasons: as a by-product of their normal operation, and because they are required to by law.

Mobile phones are constantly scanning for nearby cell towers so that when someone wants to place a call or send a text, their phone is already connected to the closest tower. This makes it faster to place a call or send a text.

To maintain quality of service, mobile phones often connect with multiple cell towers at the same time. The range of the radio signal from a cell tower can be thought of as a big bubble with the cell tower in the center. The location of a mobile phone can be calculated via triangulation based on the intersection of the bubbles surrounding each of the cell towers the phone is connected to.

In addition to cell tower triangulation, since 2001 mobile phone carriers have been required by law to provide latitude and longitude information for phones that have been used to call 911. This supports faster response times from emergency responders.

How location data ends up being shared

When people allow webpages and apps to access location data generated by their mobile phones, the software maker can share that data widely without asking for further permission. Sometimes the apps themselves do this directly through partnerships between the maker and data brokers.

More often, apps and webpages that contain advertisements share location data via a process called “real-time bidding,” which determines which ads are shown. This process involves third parties hired by advertisers, which place automated bids on the ad space to ensure that ads are shown to people who match the profile of interests the advertisers are looking for.

To identify the target audience for the ads, software embedded in the app or webpage shares information collected about the user, including their location, with the third parties placing the bids. These third parties are middlemen that can keep the data and do whatever they want with it, including selling the data to location data brokers, whether or not their bid wins the auction for the ad space.

What happens to the data once it is shared

The data acquired by location data brokers is sold widely, including to companies called location-based service providers that repackage it and sell access to tools that monitor people’s locations. Some of these tools do things like provide roadside assistance. Others are used by police, government agencies and others to track down individuals.

In October 2025, news outlets reported that U.S. Immigration and Customs Enforcement had purchased a location surveillance tool from a company called Penlink that can track movements of specific mobile devices over time in a given location. Tools like this allow users to access location data from “hundreds of millions of mobile phones” without a warrant.

Why it matters

The invisible collection, sale and repackaging of location data is a problem because location data is extremely sensitive and cannot be made anonymous. The two most common locations a person visits are their home and where they work. From this information alone, it is trivially easy to determine a person’s identity and match it with the other location data about them that these companies have acquired.

Also, most people don’t realize that the location data they allowed apps and services to collect for one purpose, like navigation or weather, can reveal sensitive personal information about them that they may not want to be sold to a location data broker. For example, a research study I published about fitness tracker data found that even though people use location data to track their route while exercising, they didn’t think about how that data could be used to infer their home address.

This lack of awareness means that people can’t be expected to anticipate that data collected through the normal use of their mobile phones might be available to, for example, U.S. Immigration and Customs Enforcement.

More restrictions on how mobile phone carriers and apps are allowed to collect and share location data – and on how the government is allowed to obtain and use location information about people – could help protect your privacy. To date, Federal Trade Commission efforts to curb carriers’ data sales have had mixed results in federal court, and only a few states are attempting to pass legislation to tackle the problem.

Emilee Rader receives funding from the National Science Foundation.

– ref. Yes, the government can track your location – but usually not by spying on you directly – https://theconversation.com/yes-the-government-can-track-your-location-but-usually-not-by-spying-on-you-directly-267808

Source: The Conversation – USA (2) – By Leonel Lagos, Associate Professor of Construction Management; Director of Research, Applied Research Center, Florida International University

As U.S. electricity demand rises and technology companies seek to build more and larger data centers to drive artificial intelligence systems, the main question arising is how to generate all that power.

According to the International Energy Agency, large-scale data centers around the world used about 460 terawatt-hours of electricity in 2022, a figure that analysts expect to continue rising years into the future.

One potential solution being proposed is nuclear energy – produced by existing large-scale nuclear power plants, reactivated old ones, new ones that might be constructed with government subsidies, and other, smaller types of nuclear plants that are in development and not yet available.

The discussion around powering AI data centers, in particular, has involved a type of nuclear power plant called a small modular reactor. According to the International Atomic Energy Agency, there are about 70 different designs being researched and developed around the world, including reactors that could one day serve small or remote communities, military applications and even ships at sea or spacecraft.

Proponents say these reactor designs provide consistent power without climate-changing carbon emissions. They can also be located close to places that need their energy, reducing dependence on the electricity grid. They are still years from being commercially available: Demonstration projects may begin construction before 2030, with commercial ones reaching operation perhaps by the mid-2030s. And there is not yet a plan from the U.S. Department of Energy to handle the radioactive waste they would generate.

I am an engineer whose work focuses on the nuclear industry, including waste handling and decommissioning of nuclear reactors. Here’s what this type of reactor is, how it works and what it can do:

The basics

There are three general sizes of nuclear reactors – only one of which, conventional nuclear plants, has been built commercially. Conventional plants are built in permanent locations on large plots of land around reactor cores as tall as 30 feet (10 meters). They usually generate more than 1,000 megawatts of power, enough to supply 700,000 to 1 million homes.

The other types are still being researched and are considerably smaller. Microreactors have cores that are small enough to fit into the trailer of a semitruck. They can be installed on land about as big as a football field and generate less than 20 megawatts.

Small modular reactors are in between. Their cores are roughly 9 feet (3 meters) across and 18 feet (6 meters) tall. The entire operation occupies an area of about 50 acres and can generate up to 300 megawatts of electricity.

Because of the reactors’ size, they can be built in factories from various components and then be shipped by truck, rail or water to the location where they are assembled.

All the different types of small modular reactors generate heat the same way: by splitting heavy atoms and capturing the heat into a variety of materials – like water, liquid metal or molten salt – that circulate through water to generate steam that drives a turbine.

They are also designed with safety features to reduce the risk and severity of accidents that might release radiation or radioactive material into the surroundings. For instance, passive systems and those based on fundamental principles like gravity can terminate nuclear reactions before they reach levels where explosions or leaks might occur. These reactors also produce less heat and have far smaller amounts of nuclear material than traditional large reactors, which can reduce the radioactivity risk as well.

Construction and deployment

Small modular reactors are well-suited to provide electricity in remote places or regions without a large power grid – places where large nuclear power plants are impractical.

Their compact design and flexible placements make them ideal for small geographical regions or industrial installations, like desalination plants, or in countries just starting to develop nuclear power.

They can be built and put into operation within two or three years – more quickly than the decade or longer it can take to secure permits and construction of standard nuclear power plants and complete construction of a large nuclear plant.

There remains a range of technical challenges before small modular reactors can actually be built and put into use. These include relatively straightforward questions like how many people are needed to operate each reactor, and more complex decisions about refinements to safety regulations, both in the U.S. and internationally. It’s also not yet clear what the best way is to manage the transport of radioactive materials, especially for reactors that use coolants other than water, which could produce new forms of radioactive waste.

Understanding the fuel

Larger nuclear power plants use fuel that is about 5% uranium-235, the element that splits in a nuclear reaction, releasing heat. But many small modular reactor designs use a different fuel, with between 5% and 20% uranium-235.

This different fuel, called “high-assay low-enriched uranium,” lets the reactors generate more electricity from a smaller volume of fuel material. And though it contains significantly more uranium than standard nuclear fuel, it remains far below the concentration of 90% uranium-235 that is used in nuclear weapons.

The more concentrated fuel also allows reactors to run longer between refueling and reduces the amount of radioactive waste that remains after the fuel is spent.

US efforts

The U.S. Department of Energy is working to develop domestic manufacturing of this type of uranium for small modular reactors, to avoid being dependent on foreign sources.

Under a government contract, a Maryland-headquartered nuclear fuel company called Centrus Energy has produced nearly 1 ton (920 kilograms) of that fuel since 2023 under a contract estimated to cost taxpayers US$120 million. In mid-2025, Centrus received a $110 million contract extension to produce that amount again by the middle of 2026.

The Department of Energy is distributing the fuel Centrus has made to five companies for demonstrations and development projects.

Managing waste

All nuclear plants require safe handling of the fuel and the resulting waste. There is no permanent place to store nuclear waste in the U.S. Most nuclear waste is stored on the land around the reactors where it was generated.

The Department of Energy says it is trying to find a place to temporarily store waste from small modular reactors, but that process has been tied up in the courts for years and may not be resolved anytime soon.

Other industrial uses

In addition to delivering electricity, small modular reactors can also directly generate large amounts of heat.

That can be useful for desalination plants, which use both electricity and heat to convert seawater into fresh water for drinking and irrigation. Remote mining operations also often need both heat and power to operate equipment, ensure living quarters are habitable and process minerals.

Small modular reactors may also be useful on university campuses. A microreactor planned for the University of Illinois will provide power and steam to campus buildings, while also teaching students how to operate nuclear plants, and offer research and demonstration opportunities for more reactor improvements in the future.

Leonel Lagos does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

– ref. What are small modular reactors, a new type of nuclear power plant sought to feed AI’s energy demand? – https://theconversation.com/what-are-small-modular-reactors-a-new-type-of-nuclear-power-plant-sought-to-feed-ais-energy-demand-268628