Building technological tools for nuclear disarmament

By Zach Winn | MIT News Office

Mentorship has played a central role in the twists and turns of Associate Professor Areg Danagoulian’s life.

As a boy, it led him first to mathematics, where a passionate teacher and mentorship from his parents instilled in him a love for the subject. He then followed in the footsteps of his physicist parents and became a physicist himself. During his career, mentorship has helped Danagoulian follow his research interests, from basic to applied nuclear physics and then to industry. More recently, Danagoulian returned to his alma mater, MIT, where he delights in guiding the students in his lab as they become mature scientists.

Joining the Institute’s faculty in 2014 was the latest phase change in a career full of shifting research interests. In that time Danagoulian, who was awarded tenure last year, has developed new technologies for detecting nuclear warhead materials, encrypting their technical details, and verifying their dismantlement.

On the edge of a breakthrough

Danagoulian could not believe his eyes. It was the beginning of 2020, and his lab had just finished running preliminary experiments with collaborators at Princeton University on a new, portable system for detecting fissionable material that could be used in nuclear warheads. The plan had been to gather baseline data and to optimize conditions from there. But as he looked at the early results, he noticed a small but unmistakable blip exactly where one would be if the system were already working.

“The dip was barely visible, but I realized it wasn’t just my eyes,” Danagoulian says. “We had this suboptimal setup and we already had a weak — but real — signal. That really motivated us. We got super excited.”

If the system could work with high enough accuracy, it could transform nuclear disarmament treaties between superpowers. In the past, such treaties have targeted the delivery systems (e.g. missiles and bomber aircraft) of the nuclear weapons rather than the weapons themselves, in part because the technology for verifying nuclear materials was not compact or sensitive enough to be used at nuclear sites. Danagoulian and his collaborators believed they were on the precipice of developing a technology that could change that.

Then the Covid-19 pandemic began. Danagoulian’s lab was temporarily closed, as was the lab at Princeton.

“We’re looking at this plot, and we’re thinking there is a gold mine waiting for us,” Danagoulian says.

After months of analyzing data and planning further experiments, Danagoulian’s lab reopened in June of last year with safety precautions in place.

“We were itching for action. The moment the doors opened, we ran into the lab,” Danagoulian recalls. “We started gathering data — and this time it was really high-quality data due to optimized experimental conditions — and suddenly all these peaks started showing up exactly where they were supposed to. It was this very rewarding thing, this sense of triumph, to do something that had never been done before on such a small scale.”

Since then, Danagoulian has been working with national labs as well as members of the policy community to raise awareness of the technology and learn more about how it could be implemented.

Danagoulian says being at MIT has further exposed him to the field of public policy, helping him build impactful technical solutions and leading to collaborations. He has also developed a related tool for hiding the design details of nuclear warheads during the verification process. That system uses a physics-based analog to common digital encryption methods to scramble data about the weapon’s design. The system addresses another major hurdle to nuclear dismantlement by allowing the international community to inspect a country’s nuclear sites without jeopardizing military secrets.

“Verification of nuclear disarmament is very important, because a treaty without verification is worse than no treaty at all,” Danagoulian says, citing the Comprehensive Test Ban Treaty that was proposed in the 1950s but not fully adopted until 1996, in part because scientists lacked the technology to reliably differentiate underground testing from seismic events.

Supporting others

Amid the multidisciplinary culture of MIT, Danagoulian decided to merge his scientific work with politics. But for his parents, who were both physicists under the Soviet Union (in modern-day Armenia), science and social issues were inseparable.

“In Soviet Armenia, being in a scientist family made you a cultural minority, and it would inevitably become part of your identity,” Danagoulian says. “Here it’s a job, not a social class. But we saw ourselves as a cultural group or a political class. Later, the independence movement in Armenia was largely led by intellectuals and scientists.”

Danagoulian’s family moved to the United States when he was 16. His parents had tough lives as physicists, and while they fostered his love for the sciences, they also encouraged their son to be a computer scientist, which they thought would bring more prosperity and job security. But Danagoulian had discovered a love for physics while preparing for college, and he decided to ignore their pleas. He went on to major in physics at MIT, where he got the chance to work with Professor Richard Milner in the Laboratory of Nuclear Science as part of the Undergraduate Research Opportunities Program (UROP).

Danagoulian completed his PhD work in nuclear physics at the University of Illinois and became a researcher at the Los Alamos National Laboratory. There, he became increasingly interested in applied science and decided to join a Boston-based company developing a cargo scanner for detecting nuclear materials at ports and border crossings around the world.

At sufficiently high energies, photons can pass through even dense structures like steel shipping containers. While working in industry, Danagoulian was trying to develop a system that would send a beam of photons into containers and scan for the subatomic particles that result from collisions with nuclear materials.

Danagoulian and collaborators developed and commercialized the system, which was deployed in the South Boston Container Terminal for two years before being abandoned during the Covid-19 pandemic, largely because of its high price tag. Danagoulian believes it was the first such system deployed in the world and considers it a major technical success. He believes it could be deployed quickly again if needed in a crisis involving nuclear terrorism.

In 2014, Danagoulian returned to MIT to join the faculty of the Department of Nuclear Science and Engineering.

“This department is very collaborative,” Danagoulian says. “Everyone is trying to help you any way they can. It’s a very supportive department, and I think my success is very much associated with the mentorship and advice I’ve gotten.”

Danagoulian has also embraced his role teaching and advising students, although he admits he had to learn to let students handle the research and experiments themselves.

“When I finally got the discipline to let go, it was very rewarding, because I started seeing my students get better, and I started seeing their work becoming better than my own work in that particular area. That was deeply gratifying,” Danagoulian says.

These days, Danagoulian is happy to be in a position to offer the support and guidance that’s played such a central role in his life.

“Most of my choices in life, when it comes to education, research, work, have been heavily influenced by mentorship,” he says. “Mentorship is critically important for shaping you, helping you pick a direction, and encouraging you. I try to help students understand they are capable of doing great things.”

Engineering Nuclear Policy

By Laura Schmidt-Hong | The Tech

As much as nuclear technology and engineering are rooted in physics and radiation, reactors and weaponry, they also involve stories of politics and negotiation, history and diplomacy. The gray decades of the Cold War and today’s evolving landscape of nuclear stability and international relations are inextricable from the technology that drives them. This sort of interdisciplinary symbiosis inspires Scott Kemp’s work in MIT’s Laboratory for Nuclear Security and Policy (LNSP).

A physicist by training, Kemp first became interested in applying politics and history to nuclear science after working in international relations and realizing the need for technical expertise in policy making. Working in the State Department as a science advisor, he noticed that “there’s a tremendous amount of policy, especially in the security space, that just makes no scientific sense whatsoever.” He earned his PhD in Public and International Affairs from Princeton University, where he wrote two dissertation-length analyses: one in history and one in nuclear engineering. The works were “essentially on the same topic, but from two different perspectives,” he said.

Now, as an associate professor of nuclear science and engineering and director of the LNSP, Kemp brings the same interdisciplinary focus to the lab. He works alongside physicists and chemists whose combined expertise enables them to solve problems and develop strategic tools.

Since its inception six years ago, the lab’s research has focused primarily on developing effective methods for treaty verification. Such verification is necessary to ensure that each nation committed to a nuclear treaty truthfully reports the number of warheads in their arsenal. Ensuring accurate self-reporting requires both political and technological approaches.

Inspired by information theory and cryptography, Kemp and Areg Danagoulian ’99, professor of nuclear science and engineering, have developed direct warhead verification protocols that can, in principle, verify the authenticity of a nation’s warheads while maintaining the secrecy of their design. Kemp explained that computers are rather poor tools to carry out such protocols: “all that does is put the burden of confidence on a computer system, and no one can prove that a computer does only what it’s supposed to do and nothing else.” Rather than using computers, they built physical systems that can apply information protection concepts. One such system is a physical implementation of a one-time pad — an encryption technique that involves a single-use key shared between two parties. This method is “the only provably secure form of encryption,” said Kemp, making it uniquely useful for treaty verification. Another system, inspired by zero-knowledge proofs, returns a null result when it compares two identical objects.

The financial stakes of all these efforts are high. According to Kemp, the United States will spend over one trillion dollars over the next three decades revamping their nuclear arsenal. That spending hinges on the United States’s conception of other nations’ nuclear postures and doctrines.

Another necessary element of verification is reconstructing the history of nuclear weapons production programs, particularly secret ones. If one day the United States negotiates a disarmament agreement with North Korea in which it relinquishes its nuclear weapons, Kemp anticipates a new question: how can the United States know how many nuclear weapons North Korea should give up?

Analytical chemistry methods developed by the LNSP may provide the answer. In a collaboration with his colleague Michael Short PhD ’10, professor of nuclear science and engineering, Kemp took advantage of the science behind alpha radiation and its effects on the microstructure of nuclear hardware. Uranium-238, the most abundant isotope of uranium found in nature, and uranium-235, the predominant isotope used in nuclear weaponry, emit alpha particles of different energies when they radioactively decay. As a result, they deposit energy at different depths, in what are known as bragg peaks, inside the materials that make up physical equipment, he said. In turn, scientists can estimate which isotopes of gaseous uranium are present in nuclear machinery by quantifying the radiation damage inside and applying conservation laws.

Kemp noted that this research manifests itself in the lab just like any other research, with one key distinction. “it’s benchwork, and it’s dirty… and it looks like any other lab,” but “it’s been selected to have this particular national security impact.”

Ultimately, through their efforts, Kemp and Short have successfully developed a method to measure structural changes from radiation in the plastic gaskets used in nuclear plants. They are still working to apply the same approach to metal parts, whose chemistry makes them more difficult analytical targets.

The lab and its research have not been immune to recent changes in the politics of nuclear technology and security, however. Kemp had a hand in developing the Iran nuclear deal, through consultations with the State Department and meetings with Iranian officials. When the United States withdrew from the deal and Trump launched a dialogue with North Korea, the LNSP began exploring ways to bring North Korea “into the fold,” Kemp said. In particular, he hopes to develop cooperative opportunities to increase the safety of North Korean reactors, manage its nuclear waste disposal, and use these efforts as a first step in building trust, he said.

Down the road, Kemp envisions the lab similarly extending its focus beyond nuclear security to “any kind of role technology might have” in existential security.

As they begin to explore the security considerations of decarbonization technologies, for instance, energy policy has captured Kemp and the department of nuclear science’s interest. In seeking the “optimal path to decarbonizing the electricity sector,” they hope to determine whether decarbonization technologies create or solve security problems. According to Kemp, vulnerabilities in the United States’ electric grid can be secured with improved planning of how new generation and transmission technologies are deployed.

Through the lab’s current and future work, Kemp ultimately hopes to maintain the interdisciplinary lines of thinking that have always inspired his and the LNSP’s research. “In an era where technology has, in a sense, outpaced our morality,” he said, it is necessary to understand that the “ability to use technology for good or for evil is so powerful that we need institutions and policies to deal with it.”

In the long run, said Kemp, “if you want to use technology to effect positive change in the world, you first need to be equipped with the skills to understand how the world works.”

MIT team demos a new method for weapons verification.

By Peter Dizikes | MIT News

How do weapons inspectors verify that a nuclear bomb has been dismantled? An unsettling answer is: They don’t, for the most part. When countries sign arms reduction pacts, they do not typically grant inspectors complete access to their nuclear technologies, for fear of giving away military secrets.

Instead, past U.S.-Russia arms reduction treaties have called for the destruction of the delivery systems for nuclear warheads, such as missiles and planes, but not the warheads themselves. To comply with the START treaty, for example, the U.S. cut the wings off B-52 bombers and left them in the Arizona desert, where Russia could visually confirm the airplanes’ dismemberment. It’s a logical approach but not a perfect one. Stored nuclear warheads might not be deliverable in a war, but they could still be stolen, sold, or accidentally detonated, with disastrous consequences for human society.

“There’s a real need to preempt these kinds of dangerous scenarios and go after these stockpiles,” says Areg Danagoulian, an MIT nuclear scientist. “And that really means a verified dismantlement of the weapons themselves.”

Now MIT researchers led by Danagoulian have successfully tested a new high-tech method that could help inspectors verify the destruction of nuclear weapons. The method uses neutron beams to establish certain facts about the warheads in question — and, crucially, uses an isotopic filter that physically encrypts the information in the measured data.

A paper detailing the experiments, “A physically cryptographic warhead verification system using neutron induced nuclear resonances,” is being published today in Nature Communications. The authors are Danagoulian, who is an assistant professor of nuclear science and engineering at MIT, and graduate student Ezra Engel. Danagoulian is the corresponding author.

High-stakes testing

The experiment builds on previous theoretical work, by Danagoulian and other members of his research group, who last year published two papers detailing computer simulations of the system. The testing took place at the Gaerttner Linear Accelerator (LINAC) Facility on the campus of Rensselaer Polytechnic Institute, using a 15-meter long section of the facility’s neutron-beam line.

Nuclear warheads have a couple of characteristics that are central to the experiment. They tend to use particular isotopes of plutonium — varieties of the element that have different numbers of neutrons. And nuclear warheads have a distinctive spatial arrangement of materials. The experiments consisted of sending a horizontal neutron beam first through a proxy of the warhead, then through a an encrypting filter scrambling the information. The beam’s signal was then sent to a lithium glass detector, where a signature of the data, representing some of its key properties, was recorded. The MIT tests were performed using molybdenum and tungsten, two metals that share significant properties with plutonium and served as viable proxies for it.

The test works, first of all, because the neutron beam can identify the isotope in question.

“At the low energy range, the neutrons’ interactions are extremely isotope-specific,” Danagoulian says. “So you do a measurement where you have an isotopic tag, a signal which itself embeds information about the isotopes and the geometry. But you do an additional step which physically encrypts it.”

That physical encryption of the neutron beam information alters some of the exact details, but still allows scientists to record a distinct signature of the object and then use it to perform object-to-object comparisons. This alteration means a country can submit to the test without divulging all the details about how its weapons are engineered.

“This encrypting filter basically covers up the intrinsic properties of the actual classified object itself,” Danagoulian explains. It would also be possible just to send the neutron beam through the warhead, record that information, and then encrypt it on a computer system. But the process of physical encryption is more secure, Danagoulian notes: “You could, in principle, do it with computers, but computers are unreliable. They can be hacked, while the laws of physics are immutable.”

The MIT tests also included checks to make sure that inspectors could not reverse-engineer the process and thus deduce the weapons information countries want to keep secret.

To conduct a weapons inspection, then, a host country would present a warhead to weapons inspectors, who could run the neutron-beam test on the materials. If it passes muster, they could run the test on every other warhead intended for destruction as well, and make sure that the data signatures from those additional bombs match the signature of the original warhead.

For this reason, a country could not, say, present one real nuclear warhead to be dismantled, but bamboozle inspectors with a series of identical-looking fake weapons. And while many additional protocols would have to be arranged to make the whole process function reliably, the new method plausibly balances both disclosure and secrecy for the parties involved. The human element Danagoulian believes putting the new method through the testing stage has been a significant step forward for his research team. “Simulations capture the physics, but they don’t capture system instabilities,” Danagoulian says. “Experiments capture the whole world.”

In the future, he would like to build a smaller-scale version of the testing apparatus, one that would be just 5 meters long and could be mobile, for use at all weapons sites. “The purpose of our work is to create these concepts, validate them, prove that they work through simulations and experiments, and then have the National Laboratories to use them in their set of verification techniques,” Danagoulian says, referring to U.S. Department of Energy scientists.

Karl van Bibber, a professor in the Department of Nuclear Engineering at the University of California at Berkeley, who has read the group’s papers, says “the work is promising and has taken a large step forward,” but adds that “there is yet a ways to go” for the project. More specifically, van Bibber notes, in the recent tests it was easier to detect fake weapons based on the isotopic characteristics of the materials rather than their spatial arrangements. He believes testing at the relevant U.S. National Laboratories — Los Alamos or Livermore — would help further assess the verification techniques on sophisticated missile designs.

Overall, van Bibber adds, speaking of the researchers, “their persistence is paying off, and the treaty verification community has got to be paying attention.”

Danagoulian also emphasizes the seriousness of nuclear weapons disarmament. A small cluster of several modern nuclear warheads, he notes, equals the destructive force of every armament fired in World War II, including the atomic bombs dropped on Hiroshima and Nagasaki. The U.S. and Russia possess about 13,000 nuclear weapons between them.

“The concept of nuclear war is so big that it doesn’t [normally] fit in the human brain,” Danagoulian says. “It’s so terrifying, so horrible, that people shut it down.”

In Danagoulian’s case, he also emphasizes that, in his case, becoming a parent greatly increased his sense that action is needed on this issue, and helped spur the current research project.

“It put an urgency in my head,” Danagoulian says. “Can I use my knowledge and my skill and my training in physics to do something for society and for my children? This is the human aspect of the work.” The research was supported, in part, by a U.S. Department of Energy National Nuclear Security Administration Award.

Armageddon’s Fingerprints: The search for illicit activity

Armageddon’s Fingerprints

Around the world a network of detectives searches for evidence of illicit nuclear activity. Is it enough to keep us safe from a nuclear catastrophe?

by Mark Wolverton | January 18, 2019

Read the full article at the Science History Institute.

Excerpt:

When routine inspections aren’t enough—as was the case with Iran before it signed in 2015 what’s known as the Iran nuclear deal (more formally, the Joint Comprehensive Plan of Action)—other measures beyond U.N. sanctions and diplomatic protests are possible. At this point inspectors become detectives or forensic specialists scrutinizing a crime scene for clues. That calls for measures beyond the usual record checking, container counting, radiation scanning, and facility tours.

“One of the best ways of hiding something is you take all the stuff out of the room and then you repaint the room,” says R. Scott Kemp, director of the Laboratory for Nuclear Security and Policy at MIT, describing a neat disappearing trick. “And if there were any uranium particles, for example, that were just absorbed onto the surface of the walls, they get coated with paint. And then if you come in with a swipe and you try to pick them up, you won’t get them, because they’re encapsulated in the paint.” Inspectors have responded with lasers, specifically laser-induced breakdown spectroscopy, where, says Kemp, “you take a laser, you hold it up to the paint, you blast it, it vaporizes the paint and anything else in it, and then it looks for characteristic emission lines associated with uranium and plutonium in that vapor.”

Coupled with other measures, including satellites that search for infrared signatures from power plants and good old-fashioned intelligence analysis, such techniques will sooner or later ferret out any ongoing violation. More difficult, however, is trying to determine past activities. A state might not be presently enriching uranium for bomb fuel or doing anything else untoward, but what if it had made and stored weapons-grade materials before the arrival of nosy IAEA inspectors? “There are not as yet ways of really reconstructing historical operation of declared sites,” Kemp says. “If we go into a place and they say, ‘Oh yeah, we hadn’t told you about this, here’s our enrichment plant, of course there was uranium, here it is.’ There really isn’t any available technique for determining, ‘Well, how much uranium did you produce and what’s the history of the operation?’ ”

What do you do when the nuclear “smoking gun” has long ago stopped smoking? Kemp and his MIT colleague, nuclear scientist Michael Short, are among a small group of researchers working to answer that question. While looking for a way to better quantify radiation damage in materials, Short encountered a long-forgotten idea from Manhattan Project scientist Eugene Wigner, who proposed that atoms and molecules in a material can be dislocated from their usual positions by ionizing radiation, such as X-rays and gamma rays, and that some of this energy can be stored by the atoms. Short reasoned if such stored energy, or “Wigner energy,” could be released under heat, it would produce a “fingerprint” of the defects and the specific events that caused them.

Short immediately recognized this capability would be useful in civilian nuclear applications, such as in assessing the condition of reactor vessels during periodic inspections. But he and Kemp realized it might have an even more important role. “Scott and I think we can take, say, the centrifuges in Iran, measure the stored energy, . . . figure out how many bombs they’ve made, and see if they’re lying [when they claim to have made a greater or lesser number of bombs].” Kemp says the technique could determine both the type and amount of radiation to which something has been exposed; in other words, you can “lift these fingerprints of history from a pipe, a plastic gasket, or even the assembly table.” That would allow them to reconstruct the past operation of an enrichment plant or other nuclear facility, thus providing data that could be checked against a state’s officially declared records.

The work is still in its early stages but has already yielded promising results. The technique can show whether a material, such as stainless steel or Teflon, has been irradiated, but the crucial issue is to be able to detect precise levels of radiation over a very short time. So far, Short says, “We can detect the equivalent of about 5 or 10 years of enrichment, which is not good enough yet.” But once the process can detect recent illegal enrichment, say, 6 months ago, it will provide foolproof means for catching treaty violations. Short adds, “The preliminary results we’ve been getting are making me excited enough to think there’s something there. We’ve just got to test more samples in more controlled conditions.”

Explained: Detecting the threat of nuclear weapons

By Meg Murphy | MIT News

Will the recent U.S. withdrawal from a 2015 accord that put restrictions on Iran’s nuclear program make it easier for Iran to pursue the bomb in secret? Not likely, according to Scott Kemp, an associate professor of nuclear science and engineering at MIT. “The most powerful insights into Iran’s nuclear program come from traditional intelligence, not from inspections by the International Atomic Energy Agency,” says Kemp.

But covert nuclear-weapon programs, whether in Iran, North Korea, or elsewhere in the world, are a major unsolved problem, according to Kemp. He recently explained the technical challenges involved in the hunt for clandestine sites. And he floated a possible solution.

What inspectors look for

Inspectors want to search for the secret production of plutonium or highly enriched uranium, says Kemp. Manufacturing an actual explosive device can be accomplished quickly and discreetly once either of these ingredients is secured in enough quantity. “The assembly work can be done in an office building, underground facility, or even in a big kitchen. It’s nearly impossible to detect once the program reaches this point.”

The good news, relatively speaking, is that manufacturing these explosive materials can leave telltale clues. “All international efforts to prevent nuclear proliferation focus on preventing the production of plutonium and highly enriched uranium,” says Kemp. “The hope is to stop the material from ever being produced in the first place, or at least in sufficient quantities to make a nuclear bomb.”

What are the telltale clues of covert production?

“The production of either plutonium or highly enriched uranium is a major operation that requires people and time,” says Kemp. The involvement of many people means traditional intelligence has some chance of finding the program. But traditional intelligence can be unreliable, especially in closed societies like North Korea. Technical mechanisms would provide a useful overlay.

Detecting plutonium production, Kemp says, is easier than detecting enriched-uranium production for several reasons. The first clue is the heat signature. “Nearly all plutonium production occurs in nuclear reactors, and they obviously produce a lot of heat,” he says. “There are clever things a country could do to hide the heat signature, but they are not simple. Infrared satellites can search for waste heat leaving buildings, or being pumped into rivers or oceans.

A second clue comes from chemical signatures. The processing of reactor fuel to extract plutonium creates chemical effluent, which could be another promising detection pathway. “In addition to plutonium, the nuclear reactor will also produce a mix of other radionuclides — and while most are trapped in the reactor, a few leak out to the environment,” says Kemp, “especially the noble gases, such as radioactive isotopes of xenon and krypton.”

Scientists may be able to detect these isotopes — xenon-131, xenon-135, and krypton-85 —when they seep into the environment. “Governments already use detectors to look for those small signatures of the operation,” he says. “But a country could do all sorts of fancy things, like cryogenically freezing the off-gas, to eliminate the chemical signature if they wanted to. So we may or may not find signs of plutonium production this way.”

And what about uranium enrichment? “It also produces a distinct chemical signature,” says Kemp, which is caused when uranium hexafluoride (UF6) gas leaks into the atmosphere. The probability of a leak is very small, but it happens. When the gas escapes into open air, water vapor causes it to decompose into hydrofluoric acid and a specific kind of dust-like aerosol. The hydrofluoric acid is not useful in terms of detection. It is too reactive and disappears whenever it touches dirt, or a building, or a tree. “You are not going to detect it at any meaningful distance,” says Kemp. But the other byproduct, the dust-like aerosol, is another story.

A new way to track secret nuclear activity

The dust produced by uranium enrichment is an aerosol called uranyl fluoride (UO2F2), and it has a chemical form that is unique to uranium processing operations, says. Kemp. He is interested in working with his colleagues on the engineering faculty to develop detectors that can identify the molecule's distinctive chemical bonds. “There are many techniques for identifying molecules, but the sensitivity required in this case is exceedingly high, and the aerosol form presents a number of other challenges,” he says.

“If we could come up with extremely sensitive detectors that are cheap enough to put around a country without a lot of fancy equipment or maintenance, we would make significant inroads into the problem of detecting clandestine uranium-enrichment programs.” Imagine, he says, something like small weather stations with a solar-powered box that has a tamper-proof seal on it. It has a tiny fan that blows air over a sensor that searches the telltale U-F bond, and then sends an alert signal if the molecule is detected.

“After a localized detection, you could use weather data to project backward and estimate the most probable places this molecule came from. If you could eventually narrow it down to a few buildings or a couple city blocks, then it would be feasible for international inspectors to request access under existing legal provisions to see what is inside.” A return to the politics

The ongoing presence of the International Atomic Energy Agency, which monitors Tehran’s most sensitive factories and research labs, is provided for by the long-established Treaty on the Non-Proliferation of Nuclear Weapons, or NPT, which Iran is unlikely to withdraw from, says Kemp. That means inspection teams can continue to check known nuclear facilities as before.

However, a special provision, called the Additional Protocol, has allowed the IAEA to have wide-ranging access over the past three years, including the right to venture out to investigate tips about suspicious sites. This provision also permits the IAEA to deploy environmental sensors of the kind Kemp wants to build. It is these extra privileges that would be at risk if Iran withdraws from the 2015 accord, says Kemp. The IAEA has used these privileges to make at least 60 visits to facilities that are not part of Iran’s declared nuclear program.

“But politics ultimately drives this in the end,” he adds. “If inspectors learned something, whether from intelligence or sensors, but were refused the additional access needed to follow up on the lead, then the international community would probably presume the worst. It would therefore still be in Iran’s interest to provide follow-up access even if they did not technically have to — that is, unless they were really hiding something.”

Technology & Nuclear Energy to Disarm North Korea

Researchers must improve ways to verify weapons declarations and collaborate on nuclear power, argues R. Scott Kemp

Read: North Korean disarmament: build technology and trust at Nature