Oekraïne loopt stralingsrisico
August 26, 2022 - Zaporizhya nuclear power plant had to use emergency backup diesel generators after Russian shelling cut electricity, interrupting vital cooling water pumped through its reactor cores.
The last of its four 750 kilovolt power lines supplying the Russian-held nuclear power plant was briefly cut on Thursday (August 25, 2022), triggering emergency protection systems and backup power for the first time.
“A secure off-site power supply from the grid is essential for ensuring nuclear safety,” IAEA Director General Rafael Mariano Grossi said in a statement.
“Almost every day there is a new incident at or near the Zaporizhzhya Nuclear Power Plant. We can’t afford to lose any more time. I’m determined to personally lead an IAEA mission to the plant in the next few days to help stabilise the nuclear safety and security situation there,” said Grossi.
In all nuclear power plants, the fission of atomic fuel gives off tremendous amounts of heat used to produce steam to power turbines that generate electricity.
All six Soviet-designed VVER-1000/320 pressurised water reactors at Zaporizhya have a primary cooling circuit in which electrical pumps push water through the reactor core. Maintaining power supply is crucial to those critical support systems.
“If the cooling is interrupted, the fuel can melt through the steel reactor vessel and -- in the most severe situation -- the containment structure can leak or rupture, releasing fission products to the environment,” Edwin Lyman of the U.S.-based Union of Concerned Scientists, said in a blog post.
That cooling process is vital to prevent a runaway chain reaction that would overheat and, in the worst case, cause a meltdown like those at Chernobyl or Fukushima.
- Explainer: Zaporizhzhia's power lines: ramparts against nuclear meltdown (Reuters)
- Director General Statement on Situation in Ukraine (IAEA)
- The Ukrainian Nuclear Plant Fire May Be Out, But the Threat Remains (Union of Concerned Scientists)
- General characteristics of the VVER-1000/320 reactor (ResearchGate)