The IAEA has given notification that the Russian invading army is asserting control over the Zaporizhzhya, Ukraine's largest nuclear power station, in contradiction of international mandates that the trained and certified staff have complete freedom to make operational decisions because they are the only ones qualified to operate their station safely.
The confluence of fighting in and around nuclear facilities together with the meltdowns in Chernobyl and Fukushima, and the shutdown of a grid switching station in the US by a couple of snipers illuminate the dangers of accidents, sabotage, and operational errors.
Nuclear plants are intrinsically unsafe, because the nuclear reaction is by nature exponential; and the fuel, even when disengaged in shutdown mode, requires constant cooling by electrically powered pumps. Interruption of the cooling will lead to radioactive steam explosions.
High powered shoulder fired rifles can penetrate cooling circulation plumbing, heat exchangers and cooling fins, as can machine guns mounted on planes, tanks, and other armored vehicles. Bullets can likewise interfere with the control and power wiring supplying the circulation pumps.
President Zelenskyy is correct that ANY BATTLES in the vicinity of nuclear facilities are nuclear terrorism. The Russian tactics of cutting off power to the civilian population is not compatible with nuclear safety, as the grid has to supply continuous power to all nuclear generators that are shut down!
Further, any operations taken hastily or out of order can likewise cause an international nuclear accident.