I read a bit on radiation and criticality, so I have some familiarity with that. I was reading about the details of the criticality accident. From what I understand, he was trying to place a neutron reflector on top of the demon core, and kept it apart only with a screwdriver wedged between the two reflector halves. The screwdriver slipped, the reflector made contact with the core, and radiation was released.
My question is, was it the physical contact of the reflector that caused the radiation to be released? How? From what I understand, reflectors speed up fission kind of how a potato cooks faster when wrapped in foil. Is it really all that it takes to cause nuclear fission, and not some elaborate bomb or reactor mechanism?
In: Physics
> My question is, was it the physical contact of the reflector that caused the radiation to be released?
No, it was the geometry of the reflectors. With the two half-sphere reflectors slightly separated the core was sub-critical, because too many neutrons escaped for a chain reaction to take place. When the two reflectors completely encased the core they reflected enough neutrons back to cause the core to become a critical mass, and a brief but intense power excursion resulted.
After a few seconds the heating of the core caused it to expand enough to drop below the criticality threshold again. That’s why it wasn’t a bomb. To get a nuclear detonation you have to force a supercritical mass by violently compressing fissile material.
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