This may well be an urban legend, but I recall in college being told that a professor of, I presume, chemistry or physics, was once giving a lecture and had two subcritical spheres of uranium or somesuch for demonstration purposes. During the course of the lecture, the spheres somehow rolled together and a fission reaction started. The professor separated them by hand and subsequently died of cancer or radiation poisoning, or whatever.
Sounds a lot like B.S. to me, but I suppose it could be a distorted version of some accident in the early days of nuclear physics.
it sounds like an urban legend, but doesn’t plutonium have to be bombarded by electrons and/or neutrons for fission to start? (P.S. if they were melding together, I think that would be fusion)
Ad Noctum, not smart at nuclear stuff, but tries to sound smart, so then he sounds like a moron.
I don’t think they were supposed to be melding together, per se, just close enough together that they formed a critical mass and began a self-sustaining reaction.
I seriously of doubt it was plutonium, as that seems far too dangerous a substance to have sitting out in the open. Not to mention difficult to get ahold of.
The (somewhat distorted) story you heard was probably that of dr. louis slotin, who worked at los alamos in the 1940s.
He is generally regarded as a hero, and he did separate the two spheres by hand, dooming him to death, but saving the lives of colleagues of his in the same room and building.
Now, Uranium is more stable also, though. our science teacher showed us some uranium in class; but it was VERY stable, relatively speaking, of course. but this is a possibility, and question that SHOULD be tackled by someone smarter than I.
I’ve always regarded Dr. Slotin as a real hero of science.
The plutonium hemispheres he pulled apart probably wouldn’t have exploded, but they were certainly spraying the area with a lot of radiation. If he hadn’t sacrificed himself, everyone in the room and probably the building would have gotten severe radiation sickness. Several would have died.
The plutonium would have soon gotten hot enough to melt, which would have burned the building and left that area of Los Alamos so contaminated with radiation it would have had to be abandoned. Since many of their experiments would be sensitive to high background radiation, it might even have forced the whole lab complex to close.
Hard to imagine the man’s presence of mind. He may have pulled apart the hemispheres reflexively, but his next actions were very well thought out. He yelled for everyone to freeze, then took a tape measure to determine how far everyone was from the accident. He went straight to the blackboard and started calculating. Soon, he finished working out how bad things were. He turned to them and told them that none of them took a high dose. He told them that his own dose was lethal. It took him nine days to die of it.
They fictionalize Slotin’s story. I guess they changed the name in deference to his family or something. Of course, the timeline was wrong for that, since Slotin’s death was a couple years after Trinity, I think.
I’ve seen a number of different movies about the Manhattan Project or the bombing, and generally, a version of the Slotin story is included, although the details and names vary.
The Slotin story came up again in the news a while ago, after a criticality incident in Japan called the “Tokaimura incident.” A uranium processing plant in Tokaimura had abandoned official safety procedures, in an attempt to save a buck. They processed uranium ore dissolved in water. They were supposed to transfer small subcritical amounts between processes using special containers, but to save time they just used big plastic buckets. They must have spent weeks carrying around barely-subcritical masses, just by the coincidence that the buckets didn’t quite hold a critical mass. But one day they were pouring buckets of uranium/water mixture a LITTLE too fast and suddenly a big blue flash of light (Cerenkov radiation) is their first indication that anything is wrong. They created a chain reaction in the liquified uranium tank. Apparently the crew was immediately incapacitated, the radiation must have been so intense that it scrambled every nerve in their body, they could not function and had to be dragged away from the reaction by a rescue crew. I believe all 3 of the crew died, and the rescue crew all got significantly dangerous radiation doses. A big dose of radiation was emitted into the environment. A bad incident all around.
You’ve got it right – Slotkin’s story was re-rranged in time (it DID happen after the war, and they changed the character’s name in "Fat Man and Little Boy), bu the story is essentially true. I’ve read it in several places, includin Walter Patterson’s book on Nuclear Power.
The story as aways bothered me, because it seems to have been such an avoidable accident. He WAS slowly allowing two hemispheres of fissile material to get closer together, using screwdrivers to keep them apart, a procedure that as KNOWN to be dangerus. They called it “Twisting the Dragon’s Tail”. The point, I have been told, was t monitor the neutron production rate as you approached a critical assembly.
With all sympathy and credit to him, i has always seemed to me that hat he did was dangerously edckless and careless. If I were to do such a thing I would make sure that if the parts were to fall out of my control, they would fall into a LSS critical than a MORE critical assembly. Mount the movablt hemisphere in a cradle UNDER the fixed upper one, for instance, s that if they fall they fall apart. don’t know if he mvie had t correct (And what else Ive read doesn’t give enough detail), but it seems that when you let the system go or if things fell, the hemispheres actually got CLOSER together, increasng the neutron flux to an incredibly high and dangerous rate. THIS is why Slotkin had to pull apart the assembly.
Mind you, he did a brave and noble thing, sacrificing himself to save his companions. (And cannot imagine, knowing as he id, tht despite not feeling any ill ffects he wuld be dead from his exposure in a matter of days), but it shouldn’t have been necessary.
The system was a mass of fissionable material resting in a hollow beryllium hemisphere, which is a neutron reflector. The equipment allowed a second hemisphere of beryllium to be lowered onto the first, bringing the system closer to criticality. There were blocks mounted on the rim of the first hemisphere to prevent criticality being achieved.
For some reason Slotin decided to remove the safety blocks and manipulate the hemispheres by hand, holding them apart with one hand and a screwdriver. As CalMeacham pointed out, this was a dangerous way to proceed and Slotin paid a high price for his own foolishness.
