Nuclear power plant substations have already been attacked dozens of times, and the current situation in the power system is a consequence of such attacks.
The threat of attacks on nuclear power plant substations is not the first time that people are talking about it — the president has emphasized this in previous years. In fact, such attacks have already occurred periodically. For example, in November 2025, the Khmelnytskyi, Rivne, and Pivdennoukrainsk nuclear power plants reduced electricity production for three weeks. This happened because large substations and power transmission lines (PTLs) through which electricity is supplied to consumers were damaged.
The Ministry of Energy of Ukraine explained that nuclear power plants reduce power (i.e. reduce electricity production) for two reasons: to protect equipment from a sudden strike or because substations are destroyed. If a missile or drone hits a high-voltage line when a nuclear power plant is operating at full power, a sharp voltage surge will occur. This can seriously damage the equipment of the plant itself. Therefore, energy workers are taking proactive measures to reduce the consequences if the network breaks down.
When Russian drones or missiles damage “Ukrenergo” substations, through which electricity from the nuclear power plant goes to consumers, the plant simply cannot “push” the generated energy into the system.
To prevent the excess energy from burning the plant’s equipment and the surviving networks, automation instantly triggers and extinguishes the reaction — this is called “power reset”. For example, this happened during the massive attack in November, which we wrote about above.
Nuclear power plants have emergency protection, although a (minor) risk remains
Nuclear power plants are designed to automatically switch to a safe mode using special safety systems. One of them is emergency or anti-accident protection — automatic "brakes" of the reactor. If external conditions are violated (for example, a substation suddenly loses power), they instantly switch the reactor to a safe state to avoid damage.
That is, when a Russian drone or missile hits the plant, the nuclear power plant loses connection to the grid. Then the automation is triggered: the plant instantly reduces power to prevent the equipment from overheating. If the external voltage disappears completely, diesel generators are turned on. They support the operation of the pumps that cool the reactor until the grid is restored.
This situation occurred on January 20 at the Chщrnobyl nuclear power plant. The Director General of the International Atomic Energy Agency (IAEA) Rafael Grossi reported that due to the shelling, the Chornobyl nuclear power plant lost all external power supply, and power lines to other nuclear power plants were also damaged. Therefore, the plant automatically started backup power sources — diesel generators.
The Chornobyl nuclear power plant after a Russian drone strike, February 14, 2025. A strike drone hit the "New Safe Confinement" (NSC), a protective arch over the 4th power unit of the Chornobyl NPP.
Even when the reactor is shut down, the nuclear fuel still releases heat (residual heat). It must be constantly cooled with water. The pumps that pump this water are powered by the grid. If there is no electricity, diesel generators are turned on at the nuclear power plant.
This situation does not mean a radiation accident, but it is the instability of the power system that is the key factor in nuclear risk. The IAEA specifically emphasizes that operation on generators is a temporary solution, as they have a limited fuel supply and require constant technical supervision in conditions of extreme cold.
“These substations are crucial for nuclear safety because they supply electricity to cool the reactors and other important safety systems,” says Rafael Grossi.
Ukraineʼs energy system is not destroyed, but it is constantly degrading
A nationwide blackout is theoretically possible, but unlikely, believes former head of “Ukrenergo” Volodymyr Kudrytskyi. Russia is not capable of completely "extinguishing" the country. The energy system is currently in acute shortage, but it is not on the verge of collapse.
Kudrytskyi also recalled that in November 2022, despite the war and constant shelling, Ukraine restored its power system in 13 hours (i.e. faster than Spain after a large-scale blackout).
Kudrytskyi predicts that the situation will ease in March, as objective factors will work in favor — the temperature will increase, electricity consumption will decrease, and solar generation will work more actively.
Energy workers dismantle a broken transformer at the Ukrenergo substation after a massive missile attack, November 10, 2022. Blackout in Kyiv, October 31, 2022.
Meanwhile, Ukraine is increasingly relying on electricity imports. Economy Minister Oleksiy Sobolev said that since October, Russia has damaged 8.5 gigawatts of Ukrainian power generation capacity — almost half of its typical electricity consumption. That is why a record amount of electricity imports is needed, Reuters reports.
CEO of security and resilience at energy “think tank Dixi Group” Olena Lapenko explained in a comment to Reuters: “Ukraine’s energy system is not destroyed, but it is operating in a mode of constant degradation.”
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