Australian news, and some related international items

Ukraine’s threatened nuclear power plant has been shut down. Has a crisis been averted? By Andrew Thorpe, with wires

The sixth and final operating reactor at Ukraine’s Zaporizhzhia nuclear power plant was shut down on Sunday to lower the risk of a radiation disaster amid the continuing fighting between Russia and Ukraine.

Key points:

  • All six of the Zaporizhzhia nuclear power plant’s reactors have now stopped, in a “cold shutdown”
  • The move diminishes the risk of meltdown as an active fission reaction is no longer taking place, but the nuclear material at the site still requires constant cooling
  • Constant shelling around the plant risks further disrupting the plant’s electricity supply and causing its cooling systems to fail

The move became possible after the plant was partially reconnected to Ukraine’s power grid, following weeks of

disconnections and reconnections caused by heavy shelling in the area damaging power lines.

The facility had been isolated from the power grid and operating in “island mode” since September 5, meaning only one reactor remained operational, generating power to run the cooling systems and other crucial processes for the rest of the plant.

Fighting near the plant, one of the 10 biggest atomic power stations in the world, fuelled fears of a disaster like the one that took place at Chernobyl in northern Ukraine in 1986, when a reactor exploded and contaminated a vast area that remains unsafe to live in.

So, are we out of the woods yet?

While Zaporizhzhia’s reactors are protected by a reinforced containment shelter that should withstand being hit by a shell or rocket, a disruption in the electrical supply to the plant risks knocking out its cooling systems, which are essential for the reactors’ safety — even after they have been shut down.

Nuclear reactor cores continue to emit radioactivity and generate heat long after they have finished operating, meaning systems that circulate water through the cores to cool them are required to stay operational for extended periods of time.

The risk of a full-scale meltdown diminishes over time once reactors cease operating, meaning Zaporizhzhia’s “cold shutdown” is a significant risk-reduction strategy — but the danger is far from over yet.

Further damage to the plant’s electricity supply, a high likelihood given the continued fighting, would require the plant to begin running its safety systems using emergency diesel generators.


September 12, 2022 - Posted by | Uncategorized

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