
This experiment proved that anyone could design a nuclear weapon - DanielRibeiro
http://io9.com/this-experiment-proved-that-anyone-could-design-a-nucle-510618426
======
Mvandenbergh
>In the 1960s World War II was well over, and the United States and the Soviet
Union were both settling into a nice, long, cold war. Both countries were
nervous, knowing that each had designed and built nuclear weapons. At least,
though, they were the only two countries that could manage it. Nice article
but it gets the time-scales slightly wrong.

The Soviet Union tested their first device in 1949.

The United Kingdom in 1952 (and their first thermonuclear bomb in 1957).

France in 1960.

China in 1964.

So by the time this programme began, all the countries in the NPT nuclear club
already had fission bombs and at least the UK had a hydrogen bomb. The idea
was not to figure out which country would be third but just how many nuclear
powers there would be. 1967 is only one year before the first countries signed
the NPT so proliferation was clearly on everyone's mind at that time.

------
venus
Good quote from one of the comments:

>> “With modern weapons-grade uranium, the background neutron rate is so low
that terrorists, if they have such material, would have a good chance of
setting off a high-yield explosion simply by dropping one half of the material
onto the other half. Most people seem unaware that if separated HEU [Highly
Enriched Uranium] is at hand it’s a trivial job to set off a nuclear explosion
… even a high school kid could make a bomb in short order.” - Luis Alvarez,
Nobel Laureate in Physics, 1988

~~~
jlgreco
I'm not so sure that it would be quite _that_ simple. You could make the
material go supercritical like that but that doesn't necessarily get you a
high-yield explosion if the mass blows itself apart too soon.

The so called "Demon Core" went supercritical when Louis Slotin accidentally
dropped a neutron reflector onto it (this was the second time out of three
that it went critical) and although it killed him, there was no explosion per-
se.

From wikipedia: _"He quickly knocked the two halves apart, stopping the chain
reaction and likely saving the lives of the other men in the laboratory,
though it is now known that the heating of the core and shells stopped the
criticality within milliseconds of its initiation."_

~~~
sp332
It might go critical, but not supercritial. It's possible to cause a large
explosion, although not the same scale as an actual bomb, by making a reactor
using control rods and then removing the rods.
<https://en.wikipedia.org/wiki/SL-1#Accident_and_response>

~~~
jlgreco
Supercriticality refers to exponential growth in the rate of fission (each
fission event in turn causing more than one additional fission event), but
unless other conditions are met then going supercritical does not mean you
actually get a nuclear bomb style explosion.

There is also the concept of prompt and delayed neutrons. Prompt neutrons are
products of the fission of the fuel, while delayed neutrons are products of
other fission products and are released shortly after the fission of fuel.

Normally nuclear reactors run prompt-subcritical, delayed critical (meaning
that each fission event causes on average less than one other fission event
with prompt neutrons, but when you account for delayed neutrons then the
average becomes one for one. The lag incurred by relying on delayed neutrons
to push you up to critical allows the system to be controlled).

During both the SL-1 accident and the second Demon Core accident, for a very
brief moment fission events were causing more than one additional fission
events with prompt neutron products. In other words they both went prompt-
critical, which _is_ a type of supercritical. Thankfully SL-1 disassembled
itself, the Demon Core rapidly heated and expanded, and neither were brought
into a supercritical configuration quickly enough. This is the fundamental
difference between what happened when the demon core went supercritical when
Louis Slotin fucked up and when it went supercritical when the they detonated
the bomb made with it over the Pacific.

 _"one of the design problems to overcome in constructing a bomb is to
contract the fissile materials and achieve prompt criticality before the chain
reaction has a chance to force the core to expand. A good bomb design must
therefore win the race to a dense, prompt critical core before a less-powerful
chain reaction (known as a fizzle) disassembles the core without allowing a
significant amount of fuel to fission. "_

<http://en.wikipedia.org/wiki/Prompt_critical#Nuclear_weapons>

The second demon core accident was a fizzle. It went supercritical but without
involving a significant amount of the fuel.

~~~
mpyne
Indeed, I have spent a _lot_ of time no farther than about 100 feet from an
operating nuclear reactor that was technically supercritical.

------
znowi
There's a catch. While it's trivial to design a gun-type bomb (Little Boy),
it's very difficult to produce weapon grade uranium for it. As for implosion-
type bomb (Fat Man), it's relatively easy to get a hold of plutonium, but the
design is extremely complex.

~~~
yk
> As for implosion-type bomb (Fat Man), it's relatively easy to get a hold of
> plutonium, but the design is extremely complex.

Relatively easy as in, you need a chemistry lab and a working breeder reactor.
To elaborate a bit, for Uranium the main task is isotope separation, this is
quite complicated since different Uranium isotopes are chemically identical
and have a mass difference of just 1%. On the other hand, more or less all
plutonium isotopes are fissile, and the task is to chemically separate them
from other elements. ( And that one needs to work with spend nuclear fuel.) On
the other hand, Plutonium does not occur naturally, so one needs a breeder
reactor to produce it first.

~~~
DennisP
But Pu240 undergoes a lot of spontaneous fission, and if you have too much of
it your bomb will fizzle. Pu238 generates a lot of decay heat, which makes it
great for NASA missions but not so great for bombs. For a while it was used in
pacemakers.

Bombs are generally made from fairly pure Pu239, which can be made by
bombarding U238 with neutrons. But if you leave the plutonium in the reactor,
you get a mix of isotopes that's pretty much useless for bombs. Separating the
isotopes is harder then enriching uranium.

For these reasons, nuclear waste from reactors, even with reprocessing, isn't
actually much of a proliferation concern.

~~~
yk
These problems are discussed in considerable detail in [1], specifically:

    
    
        While reactor grade plutonium would probably be of no 
        interest to a nation with access to better grade 
        material, it could be effectively used by a nation 
        capable of good weapon design, but without access to 
        better fissile material. Even a low technology nation 
        could fashion powerful weapons from it, after all even 
        a 1 kt device greatly exceeds the destruction of any 
        conventional weapon. 
    

So yes, recognized nuclear states are using very pure Pu239, but this is done
for engineering convenience and not an absolute necessity. And the calculation
probably changes for a state with a clandestine nuclear program, since it is
much easier to hide the additional computing capacity to make a working
reactor grade plutonium design, than it is to hide a breeder reactor.

[1] <http://nuclearweaponarchive.org/Nwfaq/Nfaq6.html> (In section _6.2.2.10
Reactor Grade Plutonium_ )

~~~
DennisP
From that section of your link: "Using this material in a bomb would be a
challenge. Continual active cooling would be needed to prevent deterioration
and damage to the core, explosives, and other components. The high rate of
neutron emission means that predetonation is inevitable, even with a very
efficient implosion system. However, even the relatively primitive Fat Man
design would have produced a 0.5 kt or so yield with this material. With
optimal implosion design yields in the range of at least several kilotons are
possible. If fusion boosting is used, then the adverse effects properties of
reactor grade plutonium can be completely overcome"

Yield restricted to a couple kilotons is generally considered a fizzle. It's
big compared to chemical explosives but only about a tenth as big as
Hiroshima. And the experiment in OP's article only talked about making a
working bomb, not an optimal one.

The point on fusion is interesting, though. It might be worth repeating the
experiment for thermonuclear bomb designs.

------
randallsquared
There's a book from the 70s, _The Curve of Binding Energy_, by John McPhee,
which is about how easy it was at that time to acquire weapons-grade materials
and design and build a device. I found it pretty interesting.

Of course, I read it in the 1980s, and here we are in the 2010s, and there's
never been a private nuclear explosion of any kind, nor apparently any nuclear
blackmail. That says something about either difficulty, or about how effective
(covert?) non-proliferation efforts have been, or about how rare is the desire
to use a nuclear weapon. Not sure which.

------
chr15p
I think the article is pretty misleading given that the British carried out
their first nuclear bomb test in 1952 and the French in 1960, it was pretty
obvious already that other countries could build a bomb.

Reading the original report they assumed a reactor capable of producing
plutonium was available so I'd say the real reasons for the experiment is to
answer questions like, "if we sell countries reactors how big a step would it
be for them to build a bomb". Given smart (but not Einstein smart) trained
physicists with access to the publicly available literature, the answer they
come to is 3 man years. Thats for an implosion device, a gun design would have
been "finished much sooner".

Reading between the lines I guess there was also an element of trying to
figure out how much of other countries nuclear programmes was based on
espionage (the British were partners in the Manhattan Project, and the Soviets
had had several spies there). They conclude that "its not surprising China has
progressed so rapidly".

Finally its also worth noting that the reviewers were less confident in the
design then the scientists were, they dont say it wouldn't work, just that it
would need testing to work out the kinks (which the designers also say they
just seem to expect less bugs :)

------
6d0debc071
There's a more in-depth article on this here:

<http://www.guardian.co.uk/world/2003/jun/24/usa.science>

I suppose the reassuring thing is that it took two fairly smart people a
significant amount of time, and that was without management giving them too
much agro, and with the ability to run experiments more or less as they
pleased via asking their supervisors to run the tests and getting the results
back.

'They were to explain at length, on paper, what part of their developing
design they wanted to test, and they would pass it, through an assigned lab
worker, into Livermore's restricted world. Days later, the results would come
back - though whether as the result of real tests or hypothetical
calculations, they would never know.'

(Quote taken from the Guardian article.)

------
floatingatoll
The appendix from the scientists documenting where they learned various things
is a thrilling read.

And, TIL that you should not use classified material as a paperweight.

"Marv Williamson (whose office was just down the hall from us) kept an
interesting paperweight on his desk.

[REDACTED: several hundred words, presumably describing it.]

We still have no idea what it really is because we don't want to ask! It was
probably because we found it here in the Laboratory that we were led to
speculate about it in the first place."

~~~
VLM
Its an interesting trivia question. One of Feynman's many autobiographical
books described how they had spheres and hemispheres of all manner of crazy
stuff to test neutron flux and explosive lens issues. He specifically
mentioned gold and silver, because normally it would be pretty insane to have
giant lumps of that stuff laying around, but given the level of perceived
security, using a hemisphere of solid 24kt gold as a desk paperweight isn't so
crazy after all. Its probably more secure on his desk than in a normal bank
vault or merely ft knox or whatever.

------
msandford
As is the case in many fields, designing != building.

For example I ride bikes. A friend of mine designed a bike for me. But since
neither of us could (at the time) weld, I had to pay someone else to assemble
it.

Just because you can design a bomb that would work doesn't mean you'd have the
ability to actually build it. Even if you were given refined uranium (and
that's 80% of the job) there's still quite a lot of work to tolerance
everything correctly, machine it all without killing yourself, assemble it,
procure the primary explosives, put together a precise enough detonation
system to allow the chain reaction to happen and then build a system to
trigger the detonation. All of that is no joke.

~~~
alan_cx
All I know is what I read in Tom Clancy's Sum of All Fears, which has a hell
of a lot of detail about building a nuclear bomb. The thing that struck me was
all the very high precision machining required, and how hard that was to
achieve.

As you suggest, design principle, easy, actually engineering it is the tricky
bit.

~~~
wtracy
Plutonium is harder to machine that other metals, as it's density tends to be
non-uniform: <http://en.wikipedia.org/wiki/Plutonium#Allotropes>

You go along milling a hard spot, then hit a soft spot and--oops! You took off
too much.

------
jd007
The hardest part of making a nuclear weapon is acquiring weapons grade (highly
enriched) uranium and/or plutonium. The actual designing/making of the bomb
itself is relatively trivial compared to the materials enrichment process (you
can easily find detailed diagrams of good bomb designs online).

~~~
caf
Even at the time of the Manhattan Project, the vast majority of the cost,
facilities and workers on the project were involved in creating the
fissionable materials rather than the better-known design work at Los Alamos.
Remember that even then, they were confident enough in the gun-type Little Boy
design that they didn't even need to test it.

------
CapitalistCartr
Building a nuke requires purified uranium or plutonium. Making that is a
massive industrial operation. Then comes casting, machining, etc. Only a
determined nation-state has a chance of success, in spite of movies. Given
that, design hasn't been a obstacle for decades.

~~~
cpleppert
Design is still a major obstacle for advanced multi-stage hydrogen bombs. How
they work exactly is still a major secret that isn't public knowledge AFAIK.

~~~
venus
Yeah, but you don't need that to get people's attention. Any nuclear bomb at
all is a Big Deal.

~~~
gizmo686
If your going for attention you don't even need to go critical. A dirty bomb
should be enough for that.

------
dbbolton
Seriously misleading title. It seems to me that this particular experiment did
_not_ prove that "anyone could make a nuclear bomb". Rather, it demonstrated
that a group of highly-educated physicists, when provided with the necessary
resources and enough time, could develop one.

I sincerely doubt that reading this study would lead one to conclude that a
member of a hunter-gatherer tribe could do the same. Perhaps "anyone" should
have been substituted with "any industrialized country" in the title.

------
rosser
Fortunately, designing one doesn't mean you'll successfully build one, and
building one doesn't mean you'll have something that actually works.

~~~
phaemon
I'm guessing the fact that it was a design for a "working atomic bomb" (from
the article) is the bit that means you'd "have something that actually works."

~~~
pyre
The generic design might be something that works, but if you don't account for
materials, tolerances, etc that are associated with the building of the
device, it could be broken.

------
dmead
covered by the guardian 6 years ago

<http://www.guardian.co.uk/world/2003/jun/24/usa.science>

<http://en.wikipedia.org/wiki/Nth_Country_Experiment>

thanks bloggers!

~~~
ChrisClark
Yes, you're right. Because it has been talked about before we should never
talk about it again. Makes sense to me. ;)

~~~
lostlogin
These seems to be a growing trend whereby general interest stories and
articles have someone calling them out as not hacking, not allowed (they are),
or dismissing them as discussed some time ago. If people up vote and its
within the guidelines isn't that all that matters?

------
ommunist
That was 60-ies. I wonder about results of this would-be nuke design these
days. I have a clue that current physics grads are unable to produce anything
like their granddads did when it comes to nukes.

------
brokenparser
'Course, there's an Emacs command to do that.

------
agnaseginoseg
Probably are a few out there in private hands.

:-/

~~~
derleth
There are few things in the world as useless as a nuclear weapon nobody else
knows you have. All of the game theory, and _that_ is where the advantage
comes from, derives from the fact people will go to extremes to keep
themselves from getting nuked even once. Keeping a Doomsday Device a secret
defeats the whole point.

~~~
Nrsolis
And yet Israel has a policy of not confirming or denying they have a working
weapon, although everyone _knows_ they do.

------
tete
I think a lot of these things are whether you _want_ to. It's just like people
do the impossible with strong will and when there is a complete lack of will
they simply never will. And building weapons and military infrastructure was
something the US always wanted - something they learned, because they learned
war, weapons and military brings money, power and a form of social
infrastructure, while still being able to call it non-socialist. Those are all
benefits. Hope that doesn't sound negative, but as a matter of fact the US has
really much power, especially with their agencies and real problems with
preventing enemy nations from building atomic bombs.

On the other hands smaller countries, like Lichtenstein, Luxembourg, Monaco,
Austria, ... probably have the resources, monetary and scientifically (else
they could buy them), but have a complete lack of interest, just like the
ordinary physics student has a complete lack of interest. In fact I even know
someone with a startup who is really scared of their technology being used for
weapons and he does everything to prevent this (they make amazing drones and
Hollywood and stuff are already really interested, cause it has a camera that
allows to make pictures/films that could not be done before). He also lost
friends because they got into military stuff - like they were killed.

Anyway, this article states that these were people who studied physics and
were not into weapons and did only use public information, but that's really
far from reality of someone who would target and have the real will to create
a nuclear weapon. Many circumstances would most likely be way better for
someone who really wants to.

Now one can do some research on this topic, but the US, kinda as part of their
military system also has a huge army when it comes to agencies and invests
like an unlimited amount of money into them, so it can pretty much flood
Iranian science institutions with agents. I mean, they often had agents that
got into way higher political positions than they intended and stuff like
that. And military spending is just extreme in the US (look it up on Wikipedia
if you haven't seen the figures yet).

So basically nuclear weapons are a lot about will, but also fear. I mean
looking at the world and how the official US tends to act a lot of states that
could have interests in such weapons doesn't want to, cause it would result
into a nearly automatic invasion, be it by agents or military from the US.

Okay, I don't know how hard it really is. I mean according to the US the Iran
was really close (weeks/months away) from the atomic bomb since the eighties
or so. I don't know what stopped them, whether it really just were agents or
whether there were other reasons, but given these facts and how much the Iran
(according to the US! (not saying you can trust the other side more though))
wants this weapons there has to be more than a bit of cyber war, which really
was more like public "look how cool we are" thing. I mean they put in agents
there to place that worm and I am pretty sure he could have done many things
and they just did it for the public.

