another nuke question

Fuego

i was recently watching a TV program about british and norwegian soldiers who sabotaged a 'heavy water' factory in nazi norway in world war 2. it was said that hitler was trying to make a nuke and that this factory was vital to its completion.

my question is, do you actually need deuterium to make a fission bomb? i thought 'heavy water' was only necessary for fusion devices? or was hitler tring to make a fusion bomb before trying a fission bomb first?

selfAdjoint

The Germans were trying to build a reactor. They relied on a mistaken experiment that said Carbon would not work as a moderator (the experimenter used chemically pure carbon, but that isn't pure inough for nuclear reactions). So they settled on heavy water as the moderator. The only source was this factory in Norway, hence the war story.

Fuego

well the program made it pretty clear that they were trying to make a bomb...

russ_watters

The way I heard it, Germany's nuke program was essentially cancelled after the lead physicist said it couldn't be done. Cleary he was wrong (specifically, he miscalculated critical mass). He was famous, but I can't remember right now who he was.

Fuego

anyway, i guess my real question is: do you need deuterium for a fission device?

LURCH

No, but you do need fissionable material. A reactor that uses heavy water as a moderator (the kind of reactor Germany was trying to build) can refine natural uranium into weapons-grade plutonium. For this reason, heavy water is a closely monitored substance to this day.

selfAdjoint

Heisenberg. Controversial to this day. Was he a hero who faked his results to deny nuclear weapons to Hitler, or a Nazi collaberator who just made a stupid mistake?

I incline to the second opinion for the following reason. When Heisenberg, who was interned with other German scientists in England, and they were bugged by the Brits, he was surprised to hear that an air delivered bomb had destroyed Hiroshima. He thought an A-bomb would have to be as big as a house. It only took him 24 hours to figure out how it was done, but that was a piece of figuring he apparently never did during the war.

Mr. Robin Parsons

Isn't it supposed to be graphite?

ranyart

Here is the source of some snipits used in the above threads.

http://www.lanl.gov/worldview/welcom...o-reactor.html