Russia’s invasion of Ukraine is putting crucial links between Ukraine’s nuclear power reactors and the electrical system in jeopardy. The nuclear sites rely on outside electricity to power vital safety systems, but those connections are fraying as news of power lines broken during the battle arrive.
The fuel of nuclear power plants generates a great amount of heat. Without cooling devices, which normally require an external power source to operate, the fuel might melt and release radioactive materials in a disastrous manner. For such a worst-case scenario to occur, numerous layers of backup systems would have to fail. However, conflict and power outages in Ukraine have analysts concerned about the country’s nuclear installations in the long run. The protracted conflict has also had an impact on radiation monitoring, communications, and long-term maintenance and cleanup activities at Ukraine’s nuclear power reactors.
« Even if the threat may not be acute right now, the progressive degradation of safety support systems [at Chernobyl] is a rising concern, » Edwin Lyman, head of nuclear power safety at the Union of Concerned Scientists, told The Verge in an email.
Chernobyl, the site of the world’s worst nuclear power plant disaster, lost power yesterday due to a failure of transmission cables. Zaporizhzhia, Ukraine’s largest operational power plant and the location of a frightening fire last week, has also suffered damage to two of the station’s four power lines.
Fortunately, the International Atomic Energy Agency (IAEA) has confirmed that the power outage at Chernobyl has had « no severe impact on safety. » Zaporizhzhia has not lost power, but the situation there has deteriorated in the six days since it was seized by Russian troops.
Any disruption in the power supply of a nuclear site is reason for concern. Grid electricity is one of the « indispensible cornerstones of nuclear safety » outlined by the IAEA last week for Ukraine. Electricity maintains fuel temperatures at acceptable levels, preventing a meltdown. It also powers critical radioactive material maintenance and monitoring equipment. Here are three major components of Ukraine’s nuclear plants that must remain operational:
Soon after the Russian invasion of Ukraine began in late February, Russian forces took Chernobyl. According to experts, the sites’ major vulnerability since then has been a cooling pool for spent fuel. It houses a large portion of the fuel from three shutdown reactors that remained operational long after the fourth reactor at the site exploded in 1986.
Even wasted fuel can generate enough heat to cause a catastrophic meltdown, thus it is typically stored in cooling pools for years. Such pools often use an external power source to pump water back and forth from the pool, keeping the water surrounding the wasted fuel cool and clean. This also keeps the water from evaporating and exposing the fuel it is meant to cover.
Experts suggest that, despite the power failure, Chernobyl’s cooling pool is likely safe for the time being since the fuel it carries has had plenty of time to cool down. « The heat load of the spent fuel storage pool and the volume of cooling water contained in the pool are sufficient to maintain effective heat removal without the requirement for electrical supply, » the IAEA announced on March 3rd, when Chernobyl lost partial power.
There are other cooling ponds in Zaporizhzhia. On March 4th, a fire broke out at the plant after it was shelled, in what some officials said as the first time a functioning nuclear power station had ever been attacked. According to the IAEA, the fire was eventually extinguished, and there was no harm to the nuclear reactors’ safety systems. However, IAEA Director General Rafael Mariano Grossi described the incident as a « near call. » Shelling or an uncontrolled fire might cut the plant’s link to the power grid.
Another source of concern is the smoldering remnants of the Chernobyl reactor. It is surrounded with a massive steel dome that was finished in 2017. That $1.7 billion facility was built to replace a decaying « sarcophagus » hurriedly constructed after the 1986 tragedy to sequester the remaining 200 metric tons of radioactive material. According to Claire Corkhill, chair in nuclear material degradation at The University of Sheffield, a ventilation system inside the dome, which requires energy, prevents the kind of corrosion that ate away at what’s left of the reactor and old sarcophagus.
Ukrenergo, Ukraine’s national power grid operator, has called for a truce around Chernobyl in order to rebuild transmission lines and restore power to the grid. The site has diesel generators with enough fuel to power the site for 48 hours, but that time is running out.
« From day to day, we witness a worsening situation at the Chernobyl NPP, particularly for radiation safety and the people managing the site under extraordinarily difficult and stressful circumstances, » Grossi stated in a statement on March 9th. « I reiterate my urgent request to the forces in effective control of the plant to follow internal radiation protection procedures, promote safe personnel rotation, and adopt other critical safety measures. »
Grossi also drew attention to the deterioration of conditions in Zaporizhzhia. « This is another another instance when the safety pillar to guarantee off-site power supply from the grid for all nuclear installations has been undermined, » he explained. As an operational power plant, the fuel in its reactors and spent-material cooling ponds is hotter than at Chernobyl. This emphasizes the importance of connecting its cooling systems to the grid.
There are still two high voltage power lines and one standby line connecting Zaporizhzhia to the grid. Zaporizhzhia typically provides roughly 20% of Ukraine’s electricity. Only two of the plant’s six nuclear reactors are currently operational. Other reactors were shut down as a precautionary measure; they will require less water for cooling but will still require some external power to operate their cooling systems. Another reason why nuclear power plants require a dependable grid is that they cannot rely on their own power when their reactors shut down.
It was always going to be difficult to manage nuclear power in a war zone, but to make matters much more difficult, Ukraine generally gets approximately half of its electricity from nuclear power facilities. The stakes of maintaining Ukraine’s nuclear power reactors safe and operating rise as a result.
According to the IAEA, this is the first time a conflict has broken out in a country with a power grid so reliant on nuclear energy.