Nuclear reactors in a war zone

What could go wrong?

The Star Trek franchise famously called the future “the undiscovered country.” I love that term because when it comes to the future, no one knows exactly what’s going to happen or how history will turn. 

Not knowing what comes next  means we’re best served if we take inherent risk into consideration when building essential systems, like, for example, how we power our society.

Nuclear power, which uses the heat from radioactive material to create energy, is inherently risky. And the consequences of what happens when you couple inherently risky technology, like nuclear power, with unanticipated events can be dire. The designers of Fukushima’s nuclear power plant in Japan didn’t anticipate an earthquake and large tsunami. The people who built most of Ukraine’s nuclear reactors likely didn’t imagine a future in which the Soviet Union would dissolve and one part of it would be attacking another with full force 30 years later.

History tells us that unanticipated events will happen. If it isn’t one thing, it’s another. And when we rely on inherently risky processes to produce our energy, we’re playing with fire. 

The current conflict in Ukraine is the most severe in human history to take place around nuclear power plants. Ukraine has 15 operable nuclear reactors and is home to Chernobyl, the site of the worst nuclear disaster in history. What does it mean for Ukraine to have nuclear reactors and accident sites in a war zone? 

Direct attack

The first risk is direct attacks on the nuclear plants. The containment vessels that house the reactor core and the radioactive fuel in most nuclear plants weren’t designed to withstand a military or terrorist attack. As such, a direct strike on a nuclear reactor has the potential to cause serious public health and environmental problems. 

In the first two weeks of the Ukraine conflict, Russian forces shelled a training building within the site of Ukraine’s six-unit Zaporizhzhia plant. This plant is the largest complex of nuclear reactors in Ukraine and produces roughly 15% of the country’s electricity. 

Power outages

A second risk to nuclear reactors is a sustained power outage. Nuclear power plants require a continuous power supply to operate safely, prevent overheating in the reactor core or spent fuel pools, and block meltdowns and radiation leaks. 

A steady supply of electricity runs pumps that circulate water in the cooling pools where spent fuel rods are stored. Without power to keep cool water cycling into the pools, excess heat from the spent fuel can boil the water in the cooling pool and evaporate it, leaving the fuel exposed. 

At Fukushima, the earthquake and subsequent tsunami wiped out electric power to the facility and damaged key equipment. This included the diesel generators that were designed to provide backup power in an emergency, which left the facility without a power source. Without the ability to pump cooling water, fuel rods inside the plant’s reactors began to heat up. As a result, three reactors at the Fukushima Daichii nuclear complex experienced meltdowns, with molten fuel slumping to the bottom of the reactor pressure vessels and, in at least one case, melting through the vessel into the final layer of containment. As operators vented steam and gases from the reactors, a series of hydrogen explosions took place, causing further damage to equipment at the complex. Large amounts of radiation were dispersed into the air.

Power outages at the Chernobyl site pose lower risk than a loss of power at operating nuclear plants. The  International Atomic Energy Administration (IAEA) has stated that there would be sufficient heat removal without electrical supply given the age of the spent fuel in the cooling ponds and the degree to which it has decayed over time. Stress tests conducted by European officials in 2011 included power loss scenarios at the Chernobyl site and those tests concluded that in the event of a loss of offsite power and backup power, the water temperature in spent fuel pools would “increase but not exceed 70 [degrees Celsius]”.

However, loss of offsite power at any of Ukraine’s other operating nuclear reactors – including the Zaporizhzhia nuclear power plant now under Russian control – could have a much greater impact on safety. Particularly if fighting were to make it impossible to obtain fuel for backup diesel generators at the plants.

A depleted labor force 

The people who work at nuclear reactors are responsible for managing the complex systems that keep the plant operating safely. 

In Ukraine, nuclear plant operators at Zaporizhzhia have been working under Russian control for weeks. International nuclear energy experts are expressing growing concerns about how reliable the operation of those Ukrainian nuclear facilities can continue under those circumstances. 

“You want nuclear plant operators to be at their best — not tired, not distracted,” said Allison Macfarlane, former chair of the U.S. Nuclear Regulatory Commission. “If they are worried about their families, or in Chernobyl’s case, not allowed to leave and reduced to eating dried porridge and canned food, they may miss things and make mistakes.” 

Mistakes at a nuclear reactor can have catastrophic ramifications. 

Where do we go from here?

In the short-term, international regulators need to do what they can to address safety concerns at Ukraine’s nuclear plants.

And as nations chart their path forward, it’s critical to recognize that humans are unable to anticipate all eventualities. We can reduce our collective risk by pivoting away from such dirty and dangerous energy sources as nuclear power and instead invest in getting our energy from cleaner and safer sources of energy like the sun and the wind. 

If you’d like to support the pivot toward a future powered 100% by clean renewable energy, you can take action by emailing your members of Congress to urge them to support federal tax credits for solar and wind. 


Johanna Neumann

Senior Director, Campaign for 100% Renewable Energy, Environment America Research & Policy Center

Johanna directs strategy and staff for Environment America's energy campaigns at the local, state and national level. In her prior positions, she led the campaign to ban smoking in all Maryland workplaces, helped stop the construction of a new nuclear reactor on the shores of the Chesapeake Bay and helped build the support necessary to pass the EmPOWER Maryland Act, which set a goal of reducing the state’s per capita electricity use by 15 percent. She also currently serves on the board of Community Action Works. Johanna lives in Amherst, Massachusetts, with her family, where she enjoys growing dahlias, biking and the occasional game of goaltimate.