What Happens When a Nuclear Site Is Hit?

Into the second month of the US-Iran war, the conflict in the Gulf continues to escalate—airstrikes widening, oil markets reacting, and pressure mounting around the Strait of Hormuz. But beyond the immediate security and economic concerns, another question is quietly taking shape: What actually happens if a nuclear site is hit?

In most cases, even if a nuclear facility is hit, a large-scale radiological disaster is unlikely. Modern sites are designed with multiple safety systems that can shut down reactors and contain damage.

The risk isn’t defined by the strike itself, but by what the strike damages inside the facility. The risk becomes significantly higher, however, if those systems fail—or if an operational nuclear power plant is directly affected.

Where the Risk Begins

On February 28, when the US and Israel launched a coordinated military campaign against Iran’s leadership and military infrastructure, Iran’s nuclear and ballistic missile sites were marked as potential targets. As the conflict deepened, Iranian officials reported strikes on the Natanz nuclear facility, a primary uranium enrichment complex, located around 140 miles from Tehran.

This was followed by strikes on the Ardakan facility as well as the Khondab heavy water reactor, which was left inoperable after the attack. Earlier this week, additional heavy bunker-buster bombs were also launched in Isfahan, in close proximity to the Isfahan Nuclear Technology Center.

So far, international watchdogs have reported no radiation leaks from the targeted facilities. The International Atomic Energy Agency (IAEA) has said there is no indication of off-site contamination, even after reported strikes on sites such as Natanz and near Isfahan.

But the concern isn’t limited to the impact site.

Across the Gulf, the risks are shaped by geography and infrastructure. Much of the region depends on desalinated seawater—systems that pull directly from the sea. If radioactive material were to enter marine environments, it wouldn’t just spread through ecosystems, but through the infrastructure that supplies drinking water to millions.

The Bushehr nuclear power plant, located along Iran’s Gulf coastline, sits within close proximity to neighboring states. While it has not been directly affected, experts have repeatedly warned that any escalation involving coastal nuclear infrastructure could have cross-border consequences.

What Happens Next

Not every strike on a nuclear site leads to a dramatic mushroom cloud explosion or an immediate radiation release. What matters is where the site is hit and how much damage is done to its safety systems.

Within minutes of impact, a reactor is designed to shut down automatically. This stops the nuclear reaction, acting as the first line of defense. But shutdown doesn’t eliminate the risk.

The reactor core continues to generate heat through radioactive decay, and that heat must be controlled. The extent of the damage—whether to buildings, control systems or backup infrastructure—determines how effectively those safety mechanisms can continue to function.

In past incidents, including the Fukushima Daiichi nuclear disaster in Japan, the shutdown worked as intended. The crisis began only after a tsunami disabled critical systems in the hours that followed.

An Iranian woman walks past a view of Tehran’s research reactor in Tehran.

PHOTOGRAPH: MORTEZA NIKOUBAZL/GETTY IMAGES