On the anniversary of Chernobyl. Those interested in this topic may not know that a similar accident could have occurred ten years earlier on the main (very first RBMK-1000 unit) Leningrad Nuclear Power Plant.
There was a nearly identical situation: one turbine in operation, reactor shutdown by emergency protection, and subsequent power escalation.
Back then, the situation was saved by the Chief Reactor Operator Mikhail
Karrask, who, acting intuitively and relying on his experience with industrial reactors, introduced into the reactor in portions
12 manual control rods
BEFORE pressing the emergency shutdown button.
A couple of years ago, Karrask passed away. This story is almost unknown outside the industry. For proof, google his obituary on Rosatom.
The technical part. The main danger of the RBMK reactors at that time was in the design of the control rods. At the bottom, they were equipped with graphite “displacers”. When the emergency shutdown button was pressed, the rods began moving down, and in the first seconds, the graphite tips did not dampen the reactor, but on the contrary, displaced the water and increased the power in the lower part of the active zone. But precisely, the instructions in case of trouble suggested pressing the emergency shutdown button. If you followed the instructions, “Chernobyl” would have happened earlier.
After the incident at the Leningrad NPP, a commission was formed. Experts (including those from the Kurchatov Institute of Atomic Energy) pointed out the dangerous design flaws of the RBMK – the positive void coefficient of reactivity and incorrect design of the rods. Unfortunately, extensive changes to the design of all RBMK reactors were not made at that time. Only operational regulations recommendations were given, which, as history showed, were insufficient to prevent the tragedy in Chernobyl.
Hi, I'm Rauf Aliev. 