Soviets made a safety experiment with a nuclear reactor in Chernobyl. It didn't go wrong at all.
Correct. The 1982, 1984, and 1985 tests of using rotational energy of the turbines to power the emergency pumping system all went just fine. The 1986 disaster happened when the operator ignored the test procedure (specifically, the instruction "Reduce reactor thermal output to between 700MW and 800MW. If reactor thermal power output drops below 700MW, abort test and shut down reactor" -- the operator reduced the power to 30MW, raised it to 200MW, and attempted to perform the test).