Watch the Chernobyl TV mini-series. If you are 40 or over, you will probably recall seeing the news when you were young. You will want to see this series. It is very, very good. Moving and true to the events that shook the day and following years.
Got to admit I was very impressed even in the bits they simplified (a single scientist representing the many in terms of the investigation). As a materials engineer, the bit with the graphite blocks was chilling.