[extropy-chat] green glasslike glaze
scerir at libero.it
Sun May 15 05:09:43 UTC 2005
From: "Gary Miller"
> I realize this is a lot of questions but I find
> the whole topic pretty interesting.
> Has anyone ever seen any good books devoted
> to this subject?
No, but there are stories about *what* was happening
at Oak Ridge, at that time :-). Oppenheimer sent there
Emilio Segré http://www.aip.org/history/esva/
and then R.Feynman. Both wrote few pages about
their missions. (Segré told me that, during that
mission, few items were stolen, at Oak Ridge,
from his luggage, which was locked. The Army
thought he was keeping some 'equations' secret
or, more probably, he was taking secrets
to Oak Ridge, from Los Alamos, and that was
Feynman reports ....
Well, I want to tell about some of the special problems
I had at Los Alamos that were rather interesting.
One thing had to do with the safety of the plant at
Oak Ridge. Los Alamos was going to make the bomb,
but at Oak Ridge they were trying to separate
the isotopes of uranium - uranium 238 and uranium 235,
the explosive one. They were just beginning to get
infinitesimal amounts from an experimental thing of 235,
and at the same time they were practicing the chemistry.
There was going to be a big plant, they were going to have
vats of the stuff, and then they were going to take
the purified stuff and repurify and get it ready for
the next stage. (You have to purify it in several stages.)
So they were practising on the one hand, and they were just
getting a little bit of U235 from one of the pieces
of apparatus experimentally on the other hand.
And they were trying to learn how to assay it, to determine
how much uranium 235 there is in it - and though we would
send them instructions, they never got it right.
So finally Segre [Emilio Segrè] said that the only
possible way to get it right was for him to go down there
and see what they were doing. The Army people said,
'No, it is our policy to keep all the information
of Los Alamos at one place.'
The people in Oak Ridge didn't know anything about
what it was to be used for; they just knew what
they were trying to do. I mean the higher people knew
they were separating uranium, but they didn't know how
powerful the bomb was, or exactly how it worked or anything.
The people underneath didn't know at all what they were doing.
And the Army wanted to keep it that way. There was no
information going back and forth. But Segre insisted they'd
never get the assays right, and the whole thing would go up
in smoke. So he finally went down to see what they were doing,
and as he was walking through he saw them wheeling a tank
carboy of water, green water - which is uranium nitrate solution.
He says, 'Uh, you're going to handle it like that
when it's purified too? Is that what you're going to do?'
They said, 'Sure - why not?'
'Won't it explode?' he says.
And so the Army said, 'You see! We shouldn't have let any
information get to them! Now they are all upset.'
Well, it turned out that the Army had realized how much
stuff we needed to make a bomb - 20 kilograms or whatever
it was - and they realized that this much material,
purified, would never be in the plant, so there was
no danger. But they did not know that the neutrons
were enormously more effective when they are slowed down
in water. And so in water it takes less than a tenth
- no, a hundredth - as much material to make a reaction
that makes radioactivity. It kills people around and so on.
So, it was very dangerous, and they had not paid any attention
to the safety at all.
So a telegram goes from Oppenheimer to Segre:
'Go through the entire plant. Notice where all the
concentrations are supposed to be, with the process
as they designed it. We will calculate in the meantime
how much material can come together before there's an explosion.'
Two groups started working on it. Christie's group worked
on water solutions and my group worked on dry powder in boxes.
We calculated about how much material they could accumulate
safely. And Christie was going to go down and tell them all
at Oak Ridge what the situation was, because this whole thing
is broken down and we have to go down and tell them now.
So I happily gave all my numbers to Christie, and said, you have
all the stuff, so go. Christie got pneumonia; I had to go.
I never traveled on an airplane before. I traveled on
an airplane. They strapped the secrets in a little thing
on my back! The airplane in those days was like a bus,
except the stations were further apart. You stopped off
every once in a while to wait.
There was a guy standing there next to me swinging a chain,
saying something like, 'It must be terribly difficult to fly
without a priority on airplanes these days.'
I couldn't resist. I said, 'Well, I don't know. I have a priority.'
A little bit later he tried again. 'It looks like this.
There are some generals coming. They are going to put off
some of us number 3's.'
'It's all right,' I said, 'I'm a number 2.'
He probably wrote to his congressman - if he wasn't
a congressman himself - saying, 'What are they doing
sending these little kids around with number 2 priorities
in the middle of the war?'
At any rate, I arrived at Oak Ridge. The first thing I did
was have them take me to the plant, and I said nothing,
I just looked at everything. I found out that the situation
was even worse than Segre reported because he noticed
certain boxes in big lots in a room, but he didn't notice
a lot of boxes in another room on the other side
of the same wall - and things like that. Now, if you have
too much stuff together, it goes up, you see.
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