Ukraine's nuclear plants: Chernobyl off diesel power, explosions explained

To the satisfaction of the International Atomic Energy Agency, at least

If you've been wondering about the fate of Ukraine's nuclear power stations amid Russia's full-on invasion of the nation, you're not alone. Here's an update from the International Atomic Energy Agency (IAEA).

The Chernobyl plant, which is being held by Russian troops, lost its connection to Ukraine's power grid on March 9, and since then it's been running its systems on power from diesel generators.

You might be wondering why that's important. It's probably not what you think. The radioactive fuel removed from Chernobyl following the 1986 disaster is set in large pools of water onsite to dissipate the heat it emits. You might think pumps are needed, and thus power required, to stop the pools from boiling off and exposing the fuel assemblies – yet according to the IAEA, no pumping is necessary. The heat load and volume of the water is such that no pumps or electrical supply are needed, we're assured.

Chernobyl running on diesel isn't the knife-edge situation you might imagine, though power from the grid would be welcome. For one thing, steady power is quite useful for the people, monitoring equipment, and computers still on site.

Specialist teams have, according to the IAEA, repaired one of two damaged high-voltage lines that connected the very-defunct facility to the power network. Ukrainian authorities told IAEA it is not known if the second power line can be repaired. The agency said Chernobyl is off the backup diesel generators.

The status of the repaired line is disputed, however. A March 14 Facebook post by Ukrainian National Power Company Ukrenergo claimed workers repaired the link, and "occupying forces" again rendered it inoperable.

Ukrainian authorities also told IAEA that information about Chernobyl comes from sources "controlled by the Russian military forces" and may therefore not be comprehensive.

The same goes for information regarding the Russian-occupied Zaporizhzhya nuclear power plant – part of which caught fire briefly after President Putin's military shelled the facility.

There were followup explosions near Zaporizhzhya after that confrontation on March 4, though these, according to the IAEA, had nothing to do with the plant's operations.

Ukraine's regulatory authority said that staff at #Zaporizhzhya Nuclear Power Plant confirmed reports that the Russian military had detonated unexploded munitions left on the site following events on 4 March. The staff had not been informed beforehand, it added.

— IAEA - International Atomic Energy Agency (@iaeaorg) March 15, 2022

While IAEA is not receiving remote data transmissions from its onsite monitoring systems at Chernobyl, it is receiving data concerning the facility that is transferred to other nuclear power plants and then passed on to the organization.

The Agency has therefore been able to confirm the 211 technical staff and guards living and working at Chernobyl are still there since the invasion kicked off on February 24.

Regulators have also told IAEA that among the four operational nuclear power plants in Ukraine, eight of the total 15 reactors are operating – including two at Zaporizhzhya.

Radiation levels at all facilities are said to be in the normal range. This assertion was corroborated by real-time monitoring tools. ®