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

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 …

  1. Pascal Monett Silver badge
    Facepalm

    Good news

    Let's just hope that Putin's stormtroopers don't start shelling nuclear power plants again.

    Icon because whew !

    1. Anonymous Coward
      Anonymous Coward

      Re: Good news

      As this article explains and contrary to most of the hysterical media coverage at the time, that's not what transpired.

      1. gryphon

        Re: Good news

        Really?

        "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."

      2. martinusher Silver badge

        Re: Good news

        The truth is always the first casualty in war.

    2. TRT Silver badge

      Re: Good news

      If I'd been sitting in that control room and heard loud booms and felt the building shake, I'd be needing a new NBC suit.

  2. fajensen
    Mushroom

    Having a bum-fight inside a "Glassware and Toxic Materials Boutique" could be bad?

  3. imanidiot Silver badge
    Boffin

    Not quite correct there.

    "The radioactive fuel removed from Chernobyl following the 1986 disaster is set in large pools of water onsite to dissipate the heat it emits."

    The spent fuel pools (SFP) at Chernobyl Nuclear Power Plant still holding water contain used fuel rod assemblies from reactors No. 1, No. 2 and No.3, which kept running until 1996, 1991 and 2000 respectively. Their latent heat will by now have dropped to levels where simple natural convection within the SFP will keep them cool enough to prevent boiling or melting from occuring. IIRC the spent fuel rods from Reactor No.4 (the one that went kaboom) were in the South Cooling Pond which is inside the building now covered by the New Safe Confinement dome and which has boiled/evaporated/drained dry following the incident (Here too, latent heat has dropped to levels where now natural air convection avoids meltdown.)

    (Even the SFP at Fukushima during the disaster and blackout never actually boiled with MUCH fresher and hotter spent fuel rod assemblies in the pool, it's estimated it reached about 60 to 70 degrees C at max)

    1. MiguelC Silver badge

      Re: Also not quite correct there.

      At Fukushima, water in one of the SPFs did boil, as this article recounts. Only a fortuitous leak from an adjacent pool prevented a much worse accident.

      1. imanidiot Silver badge

        Re: Also not quite correct there.

        It did not exceed 90 degrees according to this article: https://atomicinsights.com/oak-ridge-researchers-prove-fukushima-unit-4-spent-fuel-pool-never-a-danger/ (Thus NOT BOILING) and I've read other articles stating that the temperature likely never exceeded 70 degrees.

        Yes, the water level dropped for a multitude of reasons, evaporation being one of them but, I will repeat, there was no boiling!

    2. Jellied Eel Silver badge

      Re: Not quite correct there.

      Would a dry cooling pond result in a meltdown anyway? I thought that referred to cores, and an inability to moderate or halt fission. Presumably the risk from spent rods is they could overheat and catch fire.

      1. Elledan

        Re: Not quite correct there.

        Mostly depends on the age of the spent fuel relative to when they were removed from the reactor. Once they have been removed from the reactor and no longer subjected to the neutron chain reaction, the heat they produce is from the transuranics and other actinides that were formed as the uranium-235 did its fission thing.

        The most energetic isotopes are for example iodine, with a half-life of 8 days, so presumably at Fukushima Daiichi there would still have been quite an amount of such short-lived (and thus energetic) isotopes present, which meant that their SFP required active circulation to keep the fuel rods from getting too warm.

        In the case of Fukushima Daiichi's SFPs, they did heat up the cooling water to the point where the zirconium cladding of the fuel rods were no longer submerged, but instead got exposed to the hot steam. Steam + hot zirconium is an excellent catalyst to create hydrogen. And since TEPCO had not done the installation of hydrogen venting (which was performed at TMI), eventually this hydrogen found an ignition source and went boom, destroying the roofs of multiple of the reactor buildings. This did make it really easy for fresh cooling water to be added to the SFPs afterwards, however.

        To get a proper meltdown with corium forming and everything, you pretty much need to be running the fuel in an active reactor. When Chornobyl NPP had its meltdown, it was running the reactivity in the bottom of the reactor at roughly 10x its rated output, causing an intense formation of heat. That not only literally flipped the lid on the reactor vessel with a steam blast, but also caused the surrounding material to start melting.

        SFPs are significantly less exciting, generally being just fancy self-heated swimming pools with blue bottom lighting.

        1. imanidiot Silver badge

          Re: Not quite correct there.

          " the case of Fukushima Daiichi's SFPs, they did heat up the cooling water to the point where the zirconium cladding of the fuel rods were no longer submerged, but instead got exposed to the hot steam."

          The explosions in reactors 1 and 3 were directly from hydrogen created inside the reactor vessel itself. The explosion in the reactor building of unit 4 was likely only partially from hydrogen created in the SFP (since, as I linked above, the water level did not actually get low enough to expose the cladding, nor did the bundels get hot enough to cause extensive steam+zirconium hydrogen generation. More likely most of the hydrogen came from unit 3 through interconnects.

  4. Anonymous Coward
    Anonymous Coward

    If not radiation.....

    Then what else explains the orange glow everywhere around me this morning??

    And don't tell me it's a Saharan dust storm - that just what "they" want us to believe.

    Now, where's my lead lined tinfoil hat?

    1. TRT Silver badge

      Re: If not radiation.....

      You fell asleep on your Capri Sun stash again, didn't you? Admit it.

      Either that or you went for drinks with David Dickinson and pulled.

    2. Commswonk

      Re: If not radiation.....

      Then what else explains the orange glow everywhere around me this morning??

      You are (channeling?) Donald Trump and I claim my £5.

    3. Anonymous Coward
      Anonymous Coward

      Re: If not radiation.....

      what else explains the orange glow everywhere around me this morning?

      Did you used to be the kid in the Ready Brek advert?

    4. iron Silver badge

      Re: If not radiation.....

      Ready Brek, obviously.

      https://youtu.be/I8YHOJNQBBc

    5. Jellied Eel Silver badge

      Re: If not radiation.....

      The red is perfectly natural, and simply light underoing a red shift. This is just part of Net Zero, and switching to more sustainable, lower energy photons.

    6. Strahd Ivarius Silver badge
      Mushroom

      Re: If not radiation.....

      It is indeed very suspicious that on the eve of the anniversary of the end of the war in Algeria in the '60 a storm of lightly radioactive sand coming from the sites where the French made their bombs go boom manages to reach Europe...

  5. andy gibson

    Bragin?

    Great map, but what's with the darker purple hexagon at Bragin?

    1. TRT Silver badge

      Re: Bragin?

      According to my copy of Dragons of Glory... erm... purple hex... ah yes... It's the location of Lord Verminaard and his dragon, Ember.

  6. ThatOne Silver badge
    Devil

    What is left unsaid

    > been able to confirm the 211 technical staff and guards living and working at Chernobyl are still there

    They were buried nearby...

    1. dafe

      Re: What is left unsaid

      Their ghosts are doing the tasks now.

  7. Anonymous Coward
    Anonymous Coward

    I'm not surprised that nuclear power relies on fossil fuel.

    1. Yes Me Silver badge
      Go

      Fossils

      You need to read up on the "black start" issue. The problem is that before you can start up the main turbines that actually generate electricity, you need electricity - that's to say, you need a 50Hz supply synchronised precisely with the national grid, because when you bring up the turbines, they must be precisely synchronised with the grid. Kind of, you need a small chicken to hatch a large egg.

      So that small generator has to be powered by something - that'll be a tank of diesel.

      Come to think of it, I bet the Ukrainian grid is still synchronised to the Russian grid... [Google]... no, they switched to the European synch yesterday: Statement by Commissioner for Energy Kadri Simson on Synchronisation of the Continental European Electricity Grid with Ukraine and Moldova.

      1. Strahd Ivarius Silver badge
        Joke

        Re: Fossils

        You'd just need enough squirrels, then

  8. TDog

    Did I miss something?

    I thought power was supposed to go from the power plant to the grid?

    Something must have happened whilst I was asleep. They'll be telling me the Soviets are invading next. Sighs, still no sarcasm icon.

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