Things were rather primitive back then when building bombs.
For the first nuclear reactor, the SCRAM stood for the Safety Control Rod Axeman. His job was to cut a rope to drop the nuclear control rod, dropping the rod and ending the chain reaction.
Later, the “drop the control rod” technology killed several workers. The rod was dropped too far, the reactor overheated and blew out, the reactor over heated. Workers ran in to help and were irradiated. Eventually it was shut down, and they found the first man killed by the out of control reactor. He was pinned to the ceiling by the safety control rod. The cure was to control the position of the control rod with a worm gear, which positively controlled its position.
After one radiation accident, the chief called out for everyone to hold still, and he walked around to each of them, and they drew chalk lines around their feet to mark where they were standing during the incident. That enabled the calculation of their dose, and this was matched to their eventual symptoms and time of death to better understand the effect of radiation on the human animal.
In the tradition of Lavoisier a good scientist always wants to do one last experiment.