The job at hand for the night staff at the V. I. Lenin Nuclear Power Station near the town of Pripyat in northern Soviet Ukraine on the evening of April 25, 1986, was the procedure of closing down the plant’s number four nuclear reactor for repairs. But before this routine job, a test was to be carried out. Engineers and scientists wanted to see whether the turbine could, as it was gradually shut down, generate enough power to keep the coolant system working. To control the reactor, the operatives used a system of 167 graphite rods. These worked like a braking system that could either make the reactor work harder or slow it down, by controlling its fission rate. One possible cause of all that unfolded that night was that a 26-year-old control room operator named Leonid Toptunov, made a mistake when switching from manual to automatic control of the control rods, causing them to descend much further into the core than they should.
New European 12th May 2019 read more »