Breaking Down the Environmental Risks From Strikes on Iran's Nuclear Enrichment Sites

There is all manner of geopolitical and military fallout likely to come from the U.S. bombing of Iranian nuclear enrichment sites on June 21. What worries a lot of people more, however, is the literal fallout—the radioactive contamination that could be released when massive, bunker-buster munitions are dropped on facilities said to contain more than 400 kg (880 lbs.) of enriched uranium. Demolishing the sites, so the thinking goes, could have the same effect as detonating a so-called dirty bomb—a piece of non-fissile ordnance that spreads dangerous radioactive material across a large footprint of land and expanse of sky. But that fear is unfounded, say experts. “The attack on the enrichment sites in Iran doesn’t pose the same hazard as an accident with a functioning nuclear reactor,” says Simon Middleburgh, professor of Nuclear Engineering at the Nuclear Futures Institute at Bangor University, U.K. Any contamination is likely to be local, Middleburgh explains, because enrichment doesn’t involve fission, which is what presents the real peril when handling radioactive materials.  But that’s not to say there is no danger at all. While radioactive poisoning may be held in check, chemical poisoning—toxic exposure to gasses produced during nuclear enrichment—is another matter. “No increase in off-site radiation levels was reported,” said Rafael Mariono Grossi, director general of the International Atomic Energy Agency (IAEA) in a June 23 statement about the state of the attack sites. “[T]he main concern is chemical toxicity.” However much contamination has been released, Grossi added, the U.S. and Israel must choose any future targets carefully, especially taking pains to steer wide of Iran’s Bushehr Nuclear Power Plant, the Middle East’s first civilian nuclear reactor. Read more: What Conflict in the Middle East Means for Climate Change “I want to make it absolutely and completely clear,” Grossi warned, “[in] case of an attack on [the plant], a direct hit could result in a very high release of radioactivity to the environment.” Damage to the power grid serving the reactor could also cause its core to melt down, leading to a release of high amounts of radiation that would necessitate evacuation or protective sheltering—measures that the IAEA said would have to be taken over distances of hundreds of miles.  Here’s what else you—and the Iranian people in the nuclear crosshairs—need to know. For all the mortal mischief a nuclear weapons facility could whip up, there is very little radiation risk associated with the job of enriching uranium-235 up to the level of 90% purity needed to produce a bomb. By itself, the enriched U-235 isotope is something of “a damp squib,” says Paddy Regan, a nuclear physics professor at the U.K.’s University of Surrey. “Uranium itself is not particularly radioactive.” Iran’s 400 kg of U-235, he says, “would be much more dangerous if it fell on you.” That’s partly due to U-235’s long half-life, which measures 700 million years—the time it takes half of the material to decay away. At the sites of the U.S. attack, Regan says, “the bombing will do much more damage to the people in the locality than the poisoning.” Adds James Smith, professor of environmental science at the University of Portsmouth, “I’ve worked for a long time at Chernobyl and there’s lots of uranium from the nuclear fuel in the environment there. There’s something like six tons of it dispersed as small fuel particles. But it’s not the uranium we worry about.” Far more dangerous than U-235 are the elemental products given off when nuclear fuel goes through fission—especially iodine, strontium, and cesium. “These are the things that uranium splits into when it’s working in a reactor or a bomb,” says Smith. “Those fission products are much more densely radioactive than uranium.” An enrichment plant—which does not produce fission—poses other dangers beyond U-235’s relatively low radiation load. Those more-worrisome materials are the toxic gasses that are generated as a byproduct of the enrichment process. “When uranium is mined it’s milled into a substance called yellow cake,” says Jeffrey Lewis, professor and director of the East Asia Nonproliferation Project at Middlebury Institute of International Studies in Monterey, Calif. “This is kind of a powder. You want to enrich that material in a centrifuge, and to do that you have to transform it into a gas.” Actually, it’s transformed into multiple gasses, including uranium hexafluoride, uranyl fluoride, and hydrogen fluoride—all of which are highly corrosive and toxic when inhaled or ingested. The IAEA warns that these byproducts have likely been dispersed throughout the damaged Iranian facilities and may have escaped into the outdoor environment as well. Read more: A New Middle East Is Unfolding Before Our Eyes The best guess the IAEA has advanced at the moment is that if the gasses have indeed escaped, they have remained local, but the group cannot say so for sure. “When a bomb hits a site you can get a plume of dust and gas and debris,” says Smith. That could be carried on the wind well beyond the initial point of bunker-buster impact. The fog of war makes it difficult to ascertain exactly how badly the targeted sites have been hit and just how much radiation or chemical toxicity may have spread. The IAEA relies in part on Iran itself to report these measures; after Israel bombed the enrichment plants but before U.S. planes dropped their much heavier ordnance, the Iranians claimed there was no increase in off-site radiation levels. It’s uncertain, however, how much of that was true and how much was just all-is-well spin. For now, the IAEA plans to maintain a presence in Iran and resume inspection of the enrichment sites, as required by the nuclear Nonproliferation Treaty (NPT), of which Iran is a signatory “as soon as safety and security conditions allow,” according to the June 23 statement. Even before the American strikes, however, Iran was threatening to withdraw from the NPT, and now, battered on one side by what it considers aggression by the Israelis and on the other by the Americans, Tehran may be ill-inclined to play the good global citizen. The Trump Administration, meantime, is keeping its military options open, signalling that the weekend strike was a one-off, while at the same time retaining the option of future attacks. “Iran, the bully of the Middle East, must now make peace,” President Donald Trump said in his Saturday night address, after the bombings. “If they do not, future attacks would be far greater and a lot easier.” At present, the damage to the targeted sites seems relatively contained. Whether conditions will remain that way is impossible to say. If the truce announced late on June 23 holds, the differences among the parties could be settled without further military action.