On the night of October 25, Ukrainian authorities reported downing Russian Shahed kamikaze drones near the Khmelnitsky nuclear power plant, in the country's west. Falling debris and a wave of detonations caused significant damage to the town of Netishyn, where power plant employees live. The nearby town of Slavuta was also affected. Some buildings belonging to the nuclear facility itself were also damaged. Ukrainian President Volodymyr Zelenskyy said the drones were likely sent to attack the power plant. 

Experts from the International Atomic Energy Agency (IAEA) who are at the nuclear plant confirmed two loud explosions had occurred near the plant. They were later informed that two drones had been shot down at a distance of five and 20 kilometers, respectively.

IAEA director General Rafael Grossi later stated on the organization's website that powerful explosions near the power plant that night had temporarily cut off power to two radiation monitoring stations. According to Grossi, the detonations did not, however, disrupt the plant's operations, nor did they affect the power grid. The explosion did, meanwhile, shatter several windows at the plant. "This incident again underlines the extremely precarious nuclear safety situation in Ukraine, which will continue as long as this tragic war goes on," Grossi said. "The fact that numerous windows at the site were destroyed shows just how close it was. Next time, we may not be so fortunate."

How much damage can power plants withstand?

Nuclear power plants are Ukraine's most important sources of electricity. Their protection is particularly important as the Ukrainian power system would have difficulty functioning without them in the fall and winter, experts say. Several reactor units were shut down in the summer for repairs and only restarted before the fall, with the aim of achieving maximum power output in the winter, says nuclear energy expert Olha Kozharna. "We will not get through the winter without nuclear power plants, because last winter many thermal power plants were destroyed and we did not manage to repair them quickly and fully," says Kozharna.

Nuclear power plant reactors are well protected and can withstand even a small airplane crash, says Dmytro Humenyuk, who heads the safety and analysis unit of Ukraine's scientific and technical center on nuclear and radiation safety. That is why, in his opinion, debris from downed drones or missiles are not dangerous for nuclear power plants. They do, however, pose a risk to other energy infrastructure need to keep nuclear power plants operational. Even so, Humenyuk says any military activity near nuclear facilities pose a significant threat.

A nuclear power plant is more than just a reactor, says Humenyuk. It is a complex facility that consists of safety systems that provides electricity for the plant itself, and transports power generated by the plant. Falling debris or shelling powerlines and substations could lead to a power outage at the nuclear power plant and trigger a dangerous situation, Humenjuk says.

High-voltage substations, through which electricity produced at the nuclear power plant is fed into the power grid and without which the facility cannot function safely, must be well protected from missile and drone attacks well as falling debris. "When substations come under fire, the nuclear power plant's emergency protection is activated," says nuclear energy expert Olha Kozharna. "Such an emergency stop is very dangerous for the power plants."

Active and passive protection

Ukrenergo, the state-owned corporation operating Ukraine's energy networks, says it is trying to establish multi-level defenses around its infrastructure, especially high-voltage substations that secure the operation of nuclear power plants. The most important level of active protection is through air defense systems, Ukrenergo CEO Volodymyr Kudrytsky told DW.

Passive technical protection is also used to keep sites safe. They consists of several different layers. The first protects the plant from missile or drone debris, the second from direct drone strikes, and the third from missile impact, Kudrytsky said. "Passive protection helps ensure that our facilities remain undamaged or that the extent of damage is minimized so that, for example, we do not have an entire high-voltage substation out of order, which would have serious consequences."

That is why Ukraine hopes to its allies will continue supplying air defense systems, Ukrainian Air Force spokesman Yuriy Ihnat told DW. He did add, however, that it is not possible to concentrate air defense systems around power plants. "It is possible, of course, to work with anti-aircraft guns in the region, but these weapons have a short range," according to Ihnat. "You can use radar to lock onto targets and automatically destroy drones. So if a drone has already been missed on approach and it comes flying in, these guns are the last hope."

This article was translated from German