24 is a guilty pleasure despite technical flaws and propaganda
About the only way that plutonium could have killed George Mason in one day would be for Mason to be next to a critical mass of plutonium. No, this wouldn’t explode like bomb. Unless a critical mass is kept together (by implosion), it will heat up, expand, and effectively shut the chain reaction down. There have actually been several criticality accidents in the U.S. Two involved men working on the Manhattan Project. The first person killed in a criticality accident was Harry Daghlian. It took him 26 days to die from the resultant radiation dose. A nearly identical accident a few months later took the life of Louis Slotin in 9 days.
A very different accident was the Cecil Kelly Criticality Accident, which is discussed starting on page 250 of the linked article. Kelly’s radiation dose was massive (several thousand Rads) and he died in a day-and-a-half. Each of the criticality accidents was accompanied by a flash of light. This was Cerenkov Radiation, which can be seen as a blue light in metallic fuel, pool-type reactors (here are some neat photos)
So to sum up, if you want to see a fast-paced TV melodrama in the spirit of Saturday matinee serials with larger-than-life heroes and extremely nasty villains, then definitely watch “24”. But, don’t make the mistake of assuming that there is much, if any, factual basis for the technical aspects of the show.