First we got the bomb, and that was good, ‘Cause we love peace and motherhood. Then Russia got the bomb, but that’s okay, Cause the balance of power’s maintained that way.

Who’s next? see the video

When Tom Lehrer, mathematician (once a Los Alamos employee) and sometime singing satirist, wrote those words in the early 1960s, it seemed that one country after another was kicking down the doors to the nuclear weapons club. Lehrer’s song—“Who’s Next?”—referenced the French and Chinese atomic bombs and, because of the rush to arms, wryly speculated that even Monaco might soon have one.

Some 50 years later, where are we? The United States, the United Kingdom, Russia, France, and China have the bomb. South Africa had it . . . and gave it up. If Israel has it, it won’t say so. India and Pakistan have it and have said so. North Korea has carried out nuclear tests and has enough plutonium for several bombs. Iraq tried for the bomb, as did Libya, and both Syria and even Myanmar (formerly Burma) have been suspected of trying for it.

Who’s next? Iran?

If that never happens, credit will go to the Nuclear Nonproliferation Treaty (NPT) and the International Atomic Energy Agency (IAEA). The NPT, accepted now by 189 countries, has halted the unrestrained spread of nuclear weapons since 1970. In support of that treaty, the IAEA guards against the secret development of nuclear weapons through its safeguards program—inspections of civilian nuclear facilities around the world.

The IAEA’s more than 2,000 annual inspections are performed by the agency’s Department of Safeguards, which fields an inspection corps of 200 to 300 men and women drawn from the agency’s member countries. The results are reported to the United Nations, so the IAEA and its inspectors are often called the United Nations’ “nuclear watchdogs.”

Los Alamos National Laboratory supports that watchdog role. LANL is closely involved with the IAEA. It develops much of the safeguards technology used during inspections and trains the inspectors. And various Laboratory employees regularly take temporary leave from their positions at Los Alamos to fill IAEA jobs, either serving as techical support staff in Austria at the agency’s Vienna headquarters or traveling far and often as inspectors in the field.

A “Have–Have Not” Deal

Ironically, the need for IAEA inspections results from a tension at the heart of the agency’s and the NPT’s wellintentioned goals. Both the IAEA and the NPT promote the beneficial, peaceful uses of nuclear energy and simultaneously seek to inhibit nuclear weapon proliferation. The tension attached to this two-pronged goal centers on uranium and plutonium. Uranium fuels almost all electricitygenerating reactors and simultaneously produces plutonium, which can be reprocessed and used as fuel for the nuclear power industry. But both uranium and plutonium are also fuel for nuclear weapons and as such, can be targets for terrorists and nations that just might want their own bomb. Consequently, the IAEA’s inspections are needed to keep tabs on facilities associated with nuclear power production and on the uranium and plutonium to be found there.

Both uranium and plutonium are fuel for nuclear weapons and as such, can be targets for terrorists and for nations that just might want their own bomb.


The inspections are set in motion by formal safeguards agreements that individual nations negotiate with the agency, partially suspending their national sovereignty to allow IAEA inspectors to cross their borders and enter their nuclear facilities. As remarkable as that is, 178 states (plus Taiwan) have signed such an agreement.




The vast majority of those states have also signed the NPT and have therefore made themselves participants in a nuclear deal. NPT signatories that had already manufactured and tested nuclear weapons by January 1, 1967—the United States, the United Kingdom, Russia, France, and China (the “haves”)—agree to pursue nuclear disarmament but also to share their nuclear science expertise with the non-nuclearweapon states (the “have nots”).

For their part, the “have nots” agree never to become “haves,” but instead to use nuclear technology and materials only for civilian purposes. Underdeveloped countries, not ready for nuclear power plants, get help using nuclear technology in such fields as human health and water resource management, the latter involving the use of isotopes to study the movement of water in the environment. Developed nations get direct help establishing and safeguarding their own nuclear power industries. In return, they allow the IAEA inspections.

The Seen and the Unseen

The IAEA inspects facilities associated with all parts of the nuclear fuel cycle, which comprises all the stages uranium goes through as a fuel. Because plutonium is part of that cycle—produced in a reactor’s fuel rods—inspectors visit all the places where uranium and plutonium can be found. That begins with the facilities where uranium is converted from ore concentrate (ground or crushed ore with the waste removed) to uranium hexafluoride, a form that is ready to be enriched (its percentage of the uranium isotope U-235 increased). They also visit the enrichment facilities, fuel fabrication facilities, and, of course, nuclear reactors, where uranium is fissioned to produce heat and electricity, creating plutonium as a byproduct. At the end of the fuel cycle, they visit the facilities where spent reactor fuel rods (now containing both left over uranium and newly produced plutonium) are stored and the places where the spent fuel, once its radioactivity has declined sufficiently, is reprocessed. In reprocessing, the rods’ uranium and plutonium are separated out so they can be recovered for use in new reactor fuel—mixedoxide fuel, known as MOX fuel.

Essentially, the inspectors are auditing. Their job is to look at a facility’s records and verify the truth of the statements made there about on-site activities, about the amount of uranium and plutonium in the inventory, and about the percentage of U-235 in the uranium. In short, inspectors check the books and compare what they read there with data they collect for themselves from the actual materials. Any mismatch is a warning; a match is verification. And verification for all of a state’s nuclear facilities is verification that a state is abiding by its treaty obligations.

Part of an inspection is “low-tech.” Inspectors count fuel rods and fuel assemblies. They count and weigh containers of raw material, for example, uranium hexafluoride at a uranium enrichment plant. After uranium hexafluoride is enriched in U-235, it is converted to an oxide for use in making reactor fuel.

To detect signs of tampering, they check surveillance cameras and sensors that the IAEA has stationed at key points in a facility. They do the same for the seals on vaults, containers, and equipment.

They even take such basic steps as banging on containers to learn if they are empty and checking room layouts to see if anything has been changed or moved.

Such eyes-on tasks are vital, but the core of safeguards is measuring what cannot be seen—the radiation that reveals which uranium and plutonium isotopes are present in items such as containers and fuel rods and how much of each isotope is there. Amazingly, the inspectors can often accomplish this on site using a technique called nondestructive assay (NDA). To double check their NDA results, the inspectors often also perform destructive analysis, removing material samples and sending them to the IAEA’s Safeguards Analytical Laboratory in Seibersdorf, Austria, where laboratory techniques verify the inspectors’ on-site results and measure characteristics that cannot be measured at the facility.

Instead, they only need to place their specialized radiation detectors near an item and measure the unique radiation emanating from each isotope inside. Specifically, they are measuring neutrons and the high-energy photons known as gamma rays. These forms of radiation are continuously emitted by the isotopes of interest, and they are highly penetrating, so they come right through the walls of containers and rods.

The inspectors’ gamma-ray detectors measure the rate at which gamma rays of different energies are being emitted by the material inside an item. That information reveals the material’s isotopic composition—the ratio of one isotope to others. That ratio can distinguish reactorgrade from weapons-grade material. For example, uranium destined for a civilian power reactor is no more than 4 to 5 percent U-235. If inspectors find a higher percentage of U-235, the planned use for the uranium is suspect. Are facility operators planning to continue enrichment until the uranium reaches the 90-percent level needed for weapons?

Gamma rays can also reveal the isotopic ratios in plutonium that has been separated from spent fuel rods. That information reveals when the separation occurred. If the separation time determined by gamma-ray measurements differs from the declared time written in a facility’s records, or if the measurements reveal multiple separation times, there is a problem. The facility operators may have pulled out plutonium earlier than they said they did, or they may have done more separations than they documented. They may be producing additional, undeclared plutonium for diversion to a weapons program.

The core of safeguards is measuring what cannot be seen—the radiation that reveals which uranium and plutonium isotopes are present in items such as containers and fuel rods and how much of each isotope is there.

Detectors measuring neutrons, on the other hand, reveal mass—the amount of a particular material in an item. At a reprocessing plant, that material might be recovered plutonium inside a container. If neutron measurements show that containers hold more plutonium than the facility operator says is there, what is the purpose of that extra amount?

School for Inspectors

The NDA detectors are portable instruments for performing techniques such as gamma-ray spectroscopy and neutron coincidence (or multiplicity) counting. A very large number of these instruments were born or refined—and are constantly being improved—at Los Alamos National Laboratory. NDA is, in fact, a LANL specialty. Says Nancy Jo Nicholas, director of LANL’s Nuclear Nonproliferation and Security Programs, “At Los Alamos, we’re proud to say we helped invent safeguards technology, and by that we mean nondestructive assay. NDA is a big part of what the IAEA relies on us for.”

IAEA inspectors initially learn to wield their instruments at IAEA headquarters in the agency’s Introductory Course for Agency Safeguards (ICAS). New inspectors complete ICAS and additional training at a light-water reactor, then finish out their first year on real inspections in the company of more-experienced colleagues.

At the end of that year, they are ready to learn even more, and so they come directly to the source: the experts at Los Alamos who teach the Laboratory’s NDA Inspector Training course, specially developed for IAEA inspectors.

“We developed the technologies, we’re intimately familiar with how they work, and we’re constantly working to improve them,” says Peter Santi, coordinator of the Laboratory’s Program of Technical Support to Agency Safeguards and head of inspector training at LANL “That’s why they come here.”

A very large number of the IAEA’s NDA instruments were born or refined—and are constantly being improved—at Los Alamos.

Los Alamos started teaching the special IAEA course in 1980, and since then, all IAEA inspectors have been trained at Los Alamos. What LANL teaches takes their initial ICAS training to a higher level.

“The ICAS tells them how to take measurements and how to follow procedures, but by the time they come here, they’re experienced enough to be asking questions. They’ve figured out what they know and what they don’t know. And what they don’t know is why the techniques work,” says Santi. “So that’s what we teach them. We teach them the physics behind the measurements and where the techniques work well and where they don’t.”

Workers at the Fukushima power plant

LANL’s Brian Boyer (inset) uses an Improved Cherenkov Viewing Device (ICVD) to look at the blue glow (Cherenkov radiation) in the water around spent reactor fuel assemblies (bundles of fuel rods) in a storage pool such as this one at La Hague, France. Spent fuel is kept under water for years until its radiation levels decrease. Cherenkov radiation is caused by charged particles, from the rods, passing through the water. The glow grows dim over time as the radioactive material in the fuel rods decays, but the ICVD is meant to enhance it enough to be seen under normal facility lighting. The absence of glow around one of the rods may mean the rod is a dummy, replacing a real rod that was removed for undeclared uses. (Large photo: courtesy IAEA; inset: courtesy Brian Boyer, LANL)

The 10-day course, held 2 or 3 times a year, accommodates up to 16 students, who are drilled all day in the “schoolhouse,” a laboratory equipped with the same instruments inspectors use in the field. The students work under the direction of the people who developed these instruments. And they take measurements from a more comprehensive group of nuclear material samples than they encounter during ICAS.

Since 1980 every IAEA inspector has been trained at Los Alamos.

The course provides the students with as much one-on-one time with instructors as possible (one instructor for every two students), but the course also requires them to operate all the instruments themselves and make all their own measurements.

The intensity and breadth of classroom experience (7 to 8 hours a day) prepares inspectors to solve problems in the field. Those problems might be as mundane as dealing with malfunctioning equipment or as esoteric as working under conditions that make the measurements harder or less reliable. Measurements can be affected by material composition—whether the material in an item is a pure element or includes traces of other elements such as fluorine, beryllium, or carbon. Even an oddly shaped container of material can cause problems.

For such situations, the students learn when to switch to a different, more robust measurement technique. Or they learn to shift themselves and their equipment to more advantageous positions because measurements can also be affected by background—the nearby presence of other materials producing or blocking radiation, which can be common in a plant’s complex environment.

“The final exam,” Santi continues, “is much tougher than anything they’ll ever encounter on the job. It’s a day-long mimicked inspection of a facility, with cans full of items that have no identifier on them. The inspectors have to decide for themselves, ‘How do I measure this? How do I determine what’s in there?’”

Santi says the students are drained at the end of each day, and “when they’re done with the course, they’re done. They’ve absorbed as much as we can push into them.”

From Los Alamos—Experts and Expertise

Los Alamos people do not just teach safeguards work, they take an active part in it. LANL employees have been taking assignments at the IAEA for decades. Fifteen are there now, on temporary leave from the Laboratory. Most are serving in various positions in the Safeguards Department at IAEA headquarters, and one is a current inspector.

Nicholas actively encourages Laboratory employees to apply for IAEA jobs because she sees those opportunities as a three-way win.

“The IAEA wins because our people have the technical expertise the agency wants,” she says. “But it’s also a win for our people. The experience expands their knowledge and advances their careers, which in turn benefits the Lab. When they return, they put what they’ve learned to work on Laboratory projects.” Those projects often relate directly to safeguards work.

“The IAEA is where the rubber hits the road for safeguards technology,” says Phil Hypes, of LANL’s Systems Engineering and Integration group. Hypes was at the IAEA from 2005 to 2007 as a senior training officer for inspectors.

He continues, “We’ve developed about three-quarters of what the IAEA uses in the field, and we’re still working to push the technology forward. Having people who’ve been out there, who know the inspectors’ methods and concerns and the concerns of their technical support people, helps us refine the safeguards techniques and develop new ones. It keeps us doing good work.”

LANL does more work on technology for the IAEA than all the other national labs put together.

This good work has national backing at the highest levels. The State Department funds LANL’s development of custom safeguards equipment to meet IAEA needs. It also provides the money for the NDA Inspector Training course, and for another IAEA-specific course Los Alamos teaches: Advanced Plutonium Verification Techniques, for a smaller number of inspectors who specialize in plutonium issues.

Nicholas is forceful in her assessment of how important Los Alamos is to the IAEA’s work. “LANL does more work on technology for the IAEA than all the other national labs put together. We’re definitely the big lab of all the U.S. labs in that sense. Without Los Alamos, the IAEA could not do its job.”

–Eileen Patterson

To hear Tom Lehrer’s song—“Who’s Next?” visit

For more information visit IAEA’s Safeguards Department website:

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