EXPLAINER: How dangerous was Russia's nuclear plant strike?

[Yo_Mama_Been_Loggin]

BANGKOK (AP) — Europe’s largest nuclear power plant was hit by Russian shelling early Friday, sparking a fire and raising fears of a disaster that could affect all of central Europe for decades, like the 1986 Chernobyl meltdown.

Concerns faded after Ukrainian authorities announced that the fire had been extinguished, and while there was damage to the reactor compartment, the safety of the unit was not affected.

But even though the Zaporizhzhia nuclear plant is of a different design than Chernobyl and is protected from fire, nuclear safety experts and the International Atomic Energy Agency warn that waging war in and around such facilities presents extreme risks.

One major concern, raised by Ukraine’s state nuclear regulator, is that if fighting interrupts power supply to the nuclear plant, it would be forced to use less-reliable diesel generators to provide emergency power to operating cooling systems. A failure of those systems could lead to a disaster similar to that of Japan’s Fukushima plant, when a massive earthquake and tsunami in 2011 destroyed cooling systems, triggering meltdowns in three reactors.

https://apnews.com/article/ukraine-nuclear-power-plant-russia-attack-explainer-aaf111310ba81ec6616541c1282524cb

[PoliticAverse]

1. "waging war in and around such facilities presents extreme risks." - ya think? n/t

[grumpyduck]

2. Okay, help me out here...

If power fails to the cooling system, can't they just scram the reactor? Or is that not possible with this design?

[Hokie]

3. You just cannot lose cooling to the reactor in a high pressure water cooled plant

That is why they have multiple backup sources of power. At Fukushima Daiichi all the backup sources failed. The result was a meltdown.

Edit: I did a little reading. I guess the answer is that it depends on the design. Some of the newer designs can withstand a loss of cooling.

I am a fan of molten salt technology. They can suffer a complete blackout and nothing awful happens.

[PoliticAverse]

4. The design of most current reactors requires active cooling to be maintained for a period after

sudden shutdown in order to remove residual heat.

Otherwise fuel can melt.

Failure to maintain active cooling after shutdown is what happened at the Fukushima reactors.

[progree]

5. After the control rods have been inserted (in a scram or orderly shutdown), the decay heat

from fission products decaying is, IIRC, about 10% of the heat that the reactor generates at full power. That's plenty more than enough to melt the fuel if cooling isn't maintained.

That's what happened at Fukushima - the reactors scrammed but cooling failed due to lack of electrical power, and so the fuel inevitably melted.

What's especially scary is that they almost didn't get the power back on in time to prevent the spent fuel rods in the ABOVE GROUND, OUTSIDE OF CONTAINMENT spent fuel storage pools from melting and catching on fire . They were preparing to evacuate Tokyo if that were about to happen. But fortunately they managed to get power back on in time.