Comments by "" (@neutronalchemist3241) on "That Chernobyl Guy" channel.

  1. RBMK was '70s technology. There was a single SKALA computer (a ferrite core computer with 12kb memory, that's less than 1/5 than a Commodore 64) to control every parameter of the reactor, and it couldn't perform more than one task at any time. BTW the last SKALA had been decommissioned on Smolensk NPP Unit 3 in 2016. As explained earlier, to perform any task that was not routine running (test, or shutdown of the reactor), it was available, 24/7 a representative of the Nuclear Physics Laboratory. An experienced operator with a computer and the program that allowed to have that reading almost in real time. Unfortunately, that night, Anatoly Chernishev, the specialist on shift, had been mistakenly told, at the entrance of the reactor, that it had already been shut down, so his presence was not necessary, and he went back home.
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  2. The graphite tipped rods are still there. Due to the positive void factor (that's a "negative water presence factor"), a RBMK reactor can't work without them displacing water. What changed is that now, when the rods are fully extracted, the base of the graphite tip is at the bottom of the core, instead than 1.2m above it. When they had been made like that, not even the designers understood the risk. Otherwise they would have made them like the actual "modified" ones from the start. After the first power surges, they understood the cause and started to search for a solution, but none had been implemented at Chernobyl before the incident.
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  3. As an absorber. Despite the name a moderator, slowing down the neutrons, enhances the reactivity. Graphite is a moderator, boron is an absorber. Water is both an absorber and a moderator. What effect is prevalent, depends on the architecture of the reactor and the fuel used.
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  4.  @jfmezei  The last reading they had of the ORM, 12 minutes before the incident, gave 17-18 inserted bars, that's well within the allowed margin.
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