What is a SCRAM shutdown?

It is an emergency shutdown of a nuclear reactor by inserting a large number of negative reactions into the system. It is derived from the WWII usage of the term ‘Safety control rod axe man’ which referred to emergency situations wherein a rope was cut to stop the operations urgently and to limit the damages arising out of continuance of such an operation. The dictionary meaning of scram is to leave a place quickly, to avoid getting caught.