Why blackouts are dangerous to Ukraine’s nuclear sites

Photo credit should read Dmytro Smolyenko/Future Publishing via Getty Images

Russia's invasion of Ukraine is threatening the vital connections between the nuclear power plants and the electric grid. The nuclear sites rely on outside electricity to keep critical safety systems running, but those links are getting less reliable as reports come in about power lines damaged during the conflict.

Nuclear sites have fuel that creates heat. Without cooling systems, the fuel could melt down and cause a catastrophic release of radioactive materials. There are several layers of backup systems that would need to fail in a worst-case scenario. Experts are worried about the country's nuclear sites because of fighting and power losses. Radiation monitoring, communications, and long-term maintenance of nuclear power plants have been affected by the conflict.

The director of nuclear power safety at the Union of Concerned Scientists wrote in an email that the degradation of safety support systems at Chernobyl is a growing concern.

The site of the worst nuclear power plant disaster in history lost power yesterday after transmission lines failed. The site of an alarming fire last week has suffered damage to two power lines that supply power to the station.

The power loss to Chernobyl did not have a significant impact on safety according to the International Atomic Energy Agency. Since Russian troops took control of Zaporizhzhia, the situation there has become more worrisome.

Disruption to the power supply is a cause of concern. Electricity from the grid is one of the indispensable pillars of nuclear safety that the IAEA outlined for Ukraine last week. Fuel is kept at safe temperatures by electricity. Key maintenance and monitoring systems for radioactive materials are powered by it. Three major components at Ukraine's nuclear sites need to stay powered up.

There are cooling pools.

Russian forces seized Chernobyl after it invaded Ukraine. The biggest vulnerability since then is a cooling pool for spent fuel, according to experts. After the fourth reactor at the plant exploded in 1986, it held a lot of the fuel from three shuttered reactor.

Even spent fuel can generate enough heat to cause a disaster, so it is usually kept in cooling pools for a long time. The water surrounding the spent fuel is kept cool and clean by using an outside power source. The water is supposed to protect the fuel.

Chernobyl's cooling pool is likely safe for now because the spent fuel has had a lot of time to cool down.

There are cooling ponds in Zaporizhzhia. The first time a functioning nuclear power plant has ever been attacked was when a fire broke out at the plant on March 4th. There was no damage to the safety systems of the nuclear reactor after the fire was put out. The plant's connections to the grid could be severed if shelling or a fire were to occur.

Chernobyl's sarcophagus.

The reactor that exploded at Chernobyl is a concern. It is encased in a giant steel dome. After the 1986 disaster, a hastily built structure was built to sequester 200 metric tons of radioactive material. The kind of corrosion that ate away at the reactor and sarcophagus can be prevented by a ventilation system inside the dome.

Ukrenergo, the national power grid operator in Ukraine, has called for a ceasefire around Chernobyl so that it can repair transmission lines and restore power from the grid. The site has diesel generators that can run for 48 hours, but that time is running out.

In a March 9th statement, Grossi said that the situation at the Chernobyl Nuclear Power Plant was getting worse for radiation safety and for the staff who manage it.

There are active reactors.

The safety pillar to secure off-site power supply from the grid for all nuclear sites has been compromised. The fuel in the reactor and cooling ponds is hotter than at Chernobyl because it is an active power plant. It's important that its cooling systems are connected to the grid.

There are two more high voltage power lines that connect Zaporizhzhia to the grid. About 20 percent of the electricity in Ukranian is supplied by Zaporizhzhia. Only two of the plant's six nuclear reactor are generating power. Other reactors were shut down as a safety measure and will require less water for cooling, but still need some external power source to run their cooling systems. Nuclear power plants can't rely on their own power when their reactor shuts down because of a reliable grid.

Nuclear power in a war zone is always going to be complicated, but to make things even more difficult, Ukraine gets about half of its electricity from nuclear power plants. That raises the stakes of keeping the nuclear power plants safe.

This is the first time war has broken out in a place with a power grid that is reliant on nuclear energy.

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