Since Saturday’s U.S. aerial strikes in Iran, many have expressed concern about bombing nuclear sites, warning of potential radioactive contamination, environmental risks and serious health effects.
What Do We Know So Far About The Bombings
The uranium enrichment facilities of Fordow and Natanz were hit with massive bunker-busting bombs, meanwhile the nuclear research complex of Isfahan was targeted by an array of conventional bombs and missiles.
So far the degree of damage inside the underground facilities of Fordow and Natanz can’t be determined with certainty. Satellite images show debris scattered around the sites and several holes at the bomb entry points. The underground structures at the Natanz site, less protected, have “been extensively damaged,” the International Atomic Energy Agency noted in a press release. Referring to a preliminary report by the Defense Intelligence Agency of the Pentagon, The New York Times and CNN reported that the bombs did “substantial superficial damage” at Fordow and “closed off the entrances” but “did not collapse their underground buildings.” At the site of Isfahan 18 buildings were completely destroyed and other infrastructure “heavily damaged,” reports CNN quoting David Albright, president of the Institute for Science and International Security (ISIS).
The Sites Hadn’t Enriched Enough Uranium For A Nuclear Weapon
It is important to note that even a direct hit of a nuclear facility would not cause a nuclear explosion. An atomic bomb relies on specific, precisely engineered and timed conditions to create a supercritical mass and initiate a chain reaction. A random explosion just deforms or disintegrates the fissile material.
The two underground facilities hosted a series of centrifuges used to enrich uranium, specifically to increase the concentration of the fissile isotope uranium-235 (or U-235). At the Isfahan facility, enriched U-235 dust could potentially have been converted into fissile material for use in nuclear reactors or weapons.
Natural uranium ore contains about 0.7% of U-235 and 99.3% of other non-fissile uranium isotopes. The ore is purified, dissolved in acid and converted into uranium hexafluoride (UF6) — a gaseous compound. The UF6 is then placed inside a series of centrifuges. Due to the slight mass difference (U-235 is lighter than other uranium isotopes), the non-fissile uranium isotopes tend to move toward the outer edge when the centrifuge’s cylinder starts to spin. The gas at the center, now relatively enriched with the lighter U-235, is extracted and put into the next cylinder, repeating the cycle as long as necessary to achieve the desired level of enrichment.
To generate energy, U-235 concentrations of 3% to 6% are more than sufficient. Concentrations around 20% are used for scientific research and in radiation therapy. Producing an atomic bomb requires a concentration of 90%. Based on IAEA reports published in 2022, Iran was believed to have produced 400 kilograms of 60%-enriched U-235 so far — an unusually large quantity for civilian purposes alone.
Hazardous Materials Present At The Sites
Uranium is among the heaviest naturally occurring elements. The uranium hexafluoride as used in the centrifuges is both chemically toxic and radiologically active, but its high density makes it heavier than air. If the centrifuges were damaged, escaping UF6 flows downwards, accumulating in low-lying areas. As for uranium particles or dust, they tend to travel only short distances in the air and in groundwater (uranium is almost insoluble in water). Finally, free uranium atoms quickly react with other elements, like oxygen, forming heavy compounds resulting in an overall low mobility and contamination risk. After the attacks, both the IAEA and Iranian authorities reported that there was no off-site radiation, so if any radioactive material was released, it stayed underground and didn’t reach the surface.
What If Uranium is Released Into The Surrounding Area?
Due to the low mobility of uranium and lack of water in the desert environment, radioactive contamination by debris or wind-blown dust would likely be limited.
The half-life of U-235 is approximately 703.8 million years, reflected by a low decay rate and radioactivity. The decaying U-235 atoms emit alpha particles (essentially ionized helium nuclei), which travel only short distances. Uranium and its compounds can be safely handled under normal conditions, posing a health risk only if inhaled or ingested.
Are There Other Potential Risks From The Bombings?
Iodine-131, cesium-137 and cesium-138 are all carcinogenic isotopes considered at high risk because they can accumulate in muscle tissue and bones, but they form only during a controlled nuclear fission. There is no evidence that such isotopes were ever present at the bombed sites.
When U-235 decays it can produce radioactive radon gas, linked to higher risks of lung cancer. Radon gas can seep through debris or fissures in the bedrock, however, it tends to accumulate in closed spaces with poor air circulation, posing a low risk on the open or in rooms with adequate ventilation.
The biggest imminent environmental threat comes from excessive exposure to fluorine chemicals and leaks of toxic fuel or coolants from destroyed equipment.