Blocking Iran's Other Option: A Plutonium Bomb

America and Israel want to prevent Tehran from getting a bomb. That’s why the Pentagon and Israel Defense Forces continue to target Tehran’s ability to make weapons uranium. Washington and Jerusalem claim they have obliterated Tehran’s uranium enrichment capability. Perhaps. But, Iran has another pathway to a bomb.

ROSATOM, the Russian firm that built and has operated Bushehr since 2011, says there are 210 tons of spent reactor fuel at the plant. If you check the ROSATOM figure against International Atomic Energy Agency (IAEA) reactor performance logs, the 210 tons of waste contain enough plutonium to make more than 200 nuclear weapons – as many or more than SIPRI estimates Israel has.

Two more steps are needed to convert separated plutonium into an insertable metallic core for a nuclear implosion device First, turn the plutonium solution into an oxide and another to convert this oxide into metal. Second, cast and machine this material into a hemisphere. Assuming Iran already had an (implosion) device on the ready, the completion of a bomb could take one to two weeks. This plutonium weapon production timeline is similar to what it would take to extract the uranium hexafluoride in the rubble at Isfahan and then to chemically convert that gas into insertable metal uranium bomb cores. For that reason, the Trump administration should pay as much attention to this back end of the fuel cycle as it is to the front-end, which features uranium enrichment.

What’s odd is that there’s been next to no public discussion of Iran exploiting the Bushehr plutonium option. This may be due to the popular myth that “reactor-grade plutonium” can’t be used to make workable bombs. Robert Selden and Bruce Goodwin, two of America’s top plutonium weapons designers, put this fable to rest, most recently in 2025. As the U.S. Department of Energy has explained, with Iran’s level of weapons sophistication it could use reactor-grade and produce Hiroshima or Nagasaki yields.

The U.S. government used to worry about this possibility. In 2004, the State Department spotlighted Bushehr as a worrisome nuclear weapons plutonium producer. Late in 2012, after Iran shut Bushehr down and withdrew all of the fuel – roughly 20 bombs-worth of near-weapons-grade plutonium – the Pentagon swung into action, launching surveillance drones over the reactor to make sure the plutonium-laden spent fuel didn’t leave the plant to be reprocessed elsewhere. The Iranians put the fuel back, but the concern that Iran was trying to pull a fast one remained.

Now, the Trump Administration is threatening to bomb the largest of Iran’s electrical generating plants, of which Bushehr is in the top ten. Bombing it, much less its spent fuel pond, however, would be a big mistake. The last thing the United States should risk is prompting a radiological release. NPEC-commissioned simulations indicate radiological releases from Bushehr’s  reactor core could force the mandatory evacuation of tens of thousands to millions of Iranians. Attacking the spent fuel pond could result in even larger numbers. Of course, Bushehr would be a legitimate military target if it supported Iranian military operations. However, it doesn’t. Even before U.S. Israeli forces hit the site with two projectiles, the plant was on cold shutdown.

What, then, should our government do? First, the Pentagon should watch to make sure Iran does not remove any of the spent fuel at Bushehr. It could do this with space surveillance assets or, as it did in 2012, with drones. Second, any “peace” deal President Trump cuts with Tehran should include a requirement that there be near-real-time monitoring of the Bushehr reactor and spent fuel pond, much as the IAEA had in place with Iran’s fuel enrichment activities. The IAEA actually asked for this back in 2015. Iran refused. Unfortunately, President Obama didn’t push back. That was a mistake, one the Trump Administration should not continue to make.

Henry Sokolski is executive director of the Nonproliferation Policy Education Center. He was deputy for nonproliferation policy in the Department of Defense (1989–1993), and is the author of China, Russia, and the Coming Cool War (2024).