I have looked at many diagrams of the Chernobyl reactor and am wondering where the coolant comes from that enters the control rod channels when the control rods are raised. All the diagrams show coolant being pumped through the pipes that contain the fuel cells and then into the steam separators and back to the pumps (see enclosed diagram). All of the articles written about this reactor state that when the control rods are lowered, they displace coolant. None of the diagrams show additional coolant being pumped into the reactor vessel or being in any of the empty channels.enter image description here

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    $\begingroup$ Please fix your caps key. Why SHOUT at us? What have we done wrong? $\endgroup$
    – Solar Mike
    Jul 9, 2019 at 16:01
  • $\begingroup$ Some punctuation would also help! $\endgroup$ Jul 13, 2019 at 0:51
  • $\begingroup$ @SolarMike Thanks for the tip Mike. This was my first post... and I was trained on an IBM 360.. hence the all caps. $\endgroup$
    – JACK
    Jun 27, 2022 at 12:19

1 Answer 1


This is just a random guess, but have you considered there could be an expansion chamber? I had one in a house I owned, connected with its heating pipes (also a closed liquid system).

enter image description here Expansion tank on Wikipedia.

  • $\begingroup$ It just seems that if there was it would show up on the diagrams. I have worked on these before and they're pretty neat. $\endgroup$
    – JACK
    Jul 13, 2019 at 18:11

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