Sciencemadness Discussion Board

plutonium bomb

phangue - 12-11-2006 at 14:26

1951 to 1959, I lived with my family in Los Alamos, NM. Nuclear weaponry was very young at that time, and nobody had anything to say about how the bombs worked, except for the usual, “If you bring two sub-critical hemispheres of uranium together to form a critical mass—a nuclear detonation may result.”

The first thing that made me wonder about this, was the report of an accident over in S-site, when a worker was machining high explosives, the sample detonated, and the bodies of two workers had to be scraped off the lab walls with paint scrapers into cardboard boxes. They didn’t have blow-out walls installed at that time. Conclusion: an atomic reaction may be initiated with high explosives.

There were other clues too. A kid remarked, “My daddy said that an atomic bomb is the size of a baseball.” And then there were whispering of “moderators” and “lenses”. And then dads would bring home thick aluminum bowls from the lab, the insides roughly the size of baseballs for their kids to play with. Also my dad ask, “Did you know, phangue, that matter of any kind will detonate if sufficient pressure is applied?”

Now we know that the implosion bomb works with a plutonium core surrounded by a matrix of high explosive. That a “moderators” is requires to slow down the neutrons so as to derive appropriate products of fission. That “lenses” (I think) are shaped charges.

Would anyone like to share with us (without compromising national security):
1. The nature of the moderator. What is its composition? Is the core layered shell style, plutonium-moderator-plutonium-moderator? Or is the plutonium and moderator alloyed? How?
2. Are the shaped-charge convexes placed in the interface between the matrix and the plutonium, or somehow incorporated into the machining of the massive metal casing surrounding the active components? What?
3. What in the world were those nice little aluminum bowls that the lids were playing with? Crap! I never got one.

rotwang - 12-11-2006 at 16:19

this is all from public sources, do a search for weapon design and there is plenty of data available.
until fairly recently there were warhead designs available from the US patent office...yeah like someone is going to pay royalties or a licence on a nuclear weapon design, once thay get to the stage of making weapons concerns as to Intellectual property rights are pretty low down the list. I suppose the US could try to sue china over the ripping off of the W88 weapon design, doubt it would work.

could anyone like to share with us (without compromising national security):
1. The nature of the moderator. What is its composition? Is the core layered shell style, plutonium-moderator-plutonium-moderator? Or is the plutonium and moderator alloyed? How?

all current fission bombs rely on fast neutron fission, they do not use moderators to slow the neutrons.
the plutonium in bombs is alloyed with 1-3% of gallium, this is not for nuclear reasons rather it stabilises the plutonium in a malleable form which is much easier to compress and form using explosive compression.
I suspect that the moderators referred to were explosive moderators which shaped the explosive shock wave rather than nuclear moderators.


2. Are the shaped-charge convexes placed in the interface between the matrix and the plutonium, or somehow incorporated into the machining of the massive metal casing surrounding the active components? What?

shaped charges with lenses are not used on any current weapon design as they make the diameter of the weapon unwieldy. rather multiple simultaneous detonation points on a spherical charge are used. modern weapon tampers (the massive metal casing you refer to) are very thin, current warhead tampers are often less than 1mm thick in places. They only have to hold the weapon together for a very short period of time.

3. What in the world were those nice little aluminum bowls that the lids were playing with? Crap! I never got one.
it is likely that the aluminium bowls were simply storage containers for the core of weapons,( pits) which protected the pits from being damaged. if they

Bert - 12-11-2006 at 16:25

If you haven't seen Carey Sublette's The Nuclear Weapons FAQ, look here.
http://nuclearweaponarchive.org/Nwfaq/Nfaq4.html

Fulmen - 14-11-2006 at 03:41

1. As rotwang wrote, moderators aren't used in plutonium-weapons. Instead they have a reflector to increase yield.

2. Lenses are not shaped charges per se, but rather a explosive device that refracts the shock wave. From an initiation point the shock wave will be convex, the lens changes this into a concave wave. Distributed evenly around a spherical explosive charge they will produce a perfectly spherical shock wave that will compress the plutonium core to criticality.

3. I can assure you that the kids weren't playing with anything interesting. Any component akin to weapons, raw materials or the production would be subjected to insane secrecy and waaay to expensive for any worker to take home.

Elawr - 14-11-2006 at 09:21

Rhodes, Richard (1986). The Making of the Atomic Bomb. New York: Simon & Schuster. ISBN 0-671-44133-7.

(1995). Dark Sun: The Making of the Hydrogen Bomb. New York: Simon & Schuster. ISBN 0-684-80400-X.


[Edited on 14-11-2006 by Elawr]

[Edited on 14-11-2006 by Elawr]

Bert - 14-11-2006 at 11:10

Quote:
Originally posted by Fulmen
I can assure you that the kids weren't playing with anything interesting. Any component akin to weapons, raw materials or the production would be subjected to insane secrecy and waaay to expensive for any worker to take home.


You might be surprised at what the children of research physicists get to play with that daddy brought back home. I speak from personal experience.