Today in History - May 30: Two men killed by same cricket ball-sized sphere, a year apart

Canadian nuclear physicist Louis Slotin died in hospital on May 30, 1946, nine days after receiving a blast of hard radiation. Slotin was conducting an experiment which required placing two half-spheres of beryllium around a plutonium core. Instead of using shims to separate the devices, Slotin was using a flat-tipped screwdriver. READ MORE: Child actor had no idea he was starring in a horror movie This move would later be described as "tickling the dragon's tail".

But the screwdriver slipped, and those in the room saw a blue glow and felt a wave of heat. Slotin reported having a sudden sour taste in his mouth and a burning feeling in his hand.

But his symptoms soon worsened, having suffered what doctors described as "three-dimensional sunburn" throughout his body. READ MORE: House painter never told he was given enormous dose of plutonium Slotin was the second person to die as a result of a nuclear experiment. His co-worker at Los Alamos Laboratory in New Mexico, Harry Daghlian, had died a year earlier handling the same plutonium core. The 6kg sphere of plutonium, slightly larger than a cricket ball, would be later nicknamed the "demon core".

Too valuable and too dangerous to be discarded, the demon core would be melted down to use elsewhere. Three other scientists would be hospitalised with acute radiation sickness from the accident that killed Slotin.

But they all survived in the short term, dying between 19 and 29 years later. Slotin was presented as a hero for his actions after the accident. "Dr Slotin's quick reaction at the immediate risk of his own life prevented a more serious development of the experiment which would certainly have resulted in the death of the seven men working with him, as well as serious injury to others in the general vicinity," a statement read.

But scientists regarded him as acting like a cowboy by treating a deadly plutonium core so recklessly. For more from our Today in History archive, click here NEVER MISS A STORY: Get your breaking news and exclusive stories first by following us across all platforms. Download the 9NEWS App here via Apple and Google PlayMake 9News your preferred source on Google by ticking this box hereSign up to our breaking newsletter here