Chernobyl disaster
A turbine generator run down test was scheduled to take place before the routine shutdown. At 00:05 on April 26, the power was at around 23%. 30 minutes later the power fell to a near-zero level, probably due to change of regulator. At 01:00 the power stabilized at around 6% and the test would be run at that level. A turbine was switched off and its oscillations were measured. Shift foreman A.F. Akimov reported to deputy-chief engineer A.S. Dyatlov (who supervised the power down) that the oscillations were measured and a final briefing was given. Everyone went to their instruments and at 01:23:04 the turbine generator run down test began. Everything went completely normal.