What exactly is secret about nuclear weapons?

[Kinthalis]

A scientist couple was recently arrested for agreeing to disclose nuclear secrets to an undercover American Agent, claiming to be a representative of Venezuela.

So I wanted to know: what exactly is so secret about nuclear weapons technology? Isn't the entire process something ANY nuclear physisist out there would know pretty well? Isn't this science out of the bag already? Are the secrets down to specific quantities/ratios of materials?

In my mind this seems like getting arrested for giving up details on relativity. Not everyone understands relativity, but the science is there for anyone to explore, and the rest is Math. Any intelligent and competent scientist should be able to figure out the time dilation for a fast moving satellite, for example. He doesn't need to resort to begging Stephen Hawkins for some tips.

How is this different when it comes to Nuclear weapons, exactly? What could the couple arrested possibly have known that a nuclear physicist would otherwise not know?

[dracoi]

While the general ideas might be known, there are a lot of very specific things that have to work right to get a bomb to function. For example, the Fat Man bomb in WWII only works if you get the right kind of high explosive, arrange them in shaped charges at just the right angles, with perfect timing on the detonation. Other secrets relate to handling and purifying plutonium or uranium.

The secrets are not on par with calculating how relativity affects satellites. They're on par with building the satellite in the first place - you can't measure the time dilation if you have no satellite to measure it with. Without the satellite, all you can do is crunch numbers and wonder if it really works in real life.

[Whack-a-Mole]

The secret is in refining the fuel for the bomb (the uranium or plutonium). The broad way to go about it (centrifuges these days) are not a secret but the devil is in the details and it is a very difficult process.

Also, more refined designs are highly secret. A smart high school student with the right materials could build a functional bomb but when you get into maximizing yield and shrinking overall size and such then you get to secret stuff.

[Bijou Drains]

One quirk in US law is that even if something is already publically known, if it's still classified secret you cannot reveal it to unauthorized people.

[TriPolar]

There are a large number of secrets regarding the means of starting the reaction in a nuclear weapon, even if the materials could be obtained to make one. There are still question about the N. Korean bomb that may not have fully detonated. The hydrogen bomb is much more difficult to build and detonate. Even though the basic process of fission and fusion bombs is publicly known, there are many classified secrets held by the few countries which have ever built and detonated these devices.

The modern world has new problems with nuclear materials. Once the materials for a such weapons are obtained, it doesn't take a great deal of knowledge to produce a 'dirty' bomb, using conventional explosives to disperse radioactive material over a populated area. Even if such a bomb were ineffective in spreading radioactive material, it could cause great harm by inducing a panic.

I could tell you all the secrets in detail, but then I'd have to...

[Kinthalis]

::gets sniped through the window::

[robby]

The science behind nuclear weapons is not the secret. The secret is the specific design details necessary to construct a working nuclear weapon. A random nuclear physicist would know all of the science, but would not have any particular knowledge of the design details of a weapon.

More generally, the main reason that nuclear weapons have not proliferated all that much (relatively speaking) is because:

1. Uranium fission bombs are relatively easy to construct, but it is very difficult to obtain and enrich naturally occurring uranium into weapons-grade U-235. It generally takes the resources of an industrialized nation to operate the centrifuges necessary to enrich the uranium. (Uranium fission bombs were so easily figured outback during the Manhattan project that the design was never even tested--the first uranium fission device ever produced was detonated over Hiroshima.)

2. Plutonium is both difficult to obtain and difficult to design and build a working weapon using it. Plutonium is not naturally occurring, but requires a nuclear reactor to produce. The precisely shaped and timed explosive "lenses" are even more difficult to design and build, which are necessary to construct a working weapon. Nobody except a nuclear-weapons expert would be capable of designing and construction a working plutonium weapon, even if they already had the plutonium.

[janeslogin]

Among the things I worked with that were classified as 'secret' back in the 1960s were embarrassments. [I was working on a nuclear deterrent program.] We classified stuff because we didn't want our own people to know there money was ill spent. We assumed that the Soviets knew. We didn't want your newspaper to know.

[Candyman74]

Other secrets include actual nuclear capabilities and stockpiles. What you can read on the internet is unlikely to be accurate. People who need to know know the actual figures, but it's not public knowledge.

[D18]

Slightly on topic - remember the big brouhaha over the kid who supposedly designed a nuclear bomb as either a high school or university project in the 1970s? Does anyone know whether he really designed a workable weapon, or was it largely figuring things out on a more theoretical basis?

[aruvqan]

Originally Posted by D18

Slightly on topic - remember the big brouhaha over the kid who supposedly designed a nuclear bomb as either a high school or university project in the 1970s? Does anyone know whether he really designed a workable weapon, or was it largely figuring things out on a more theoretical basis?

Yup, and I also have a copy of the issue of the SF mag that has the plans to turn a whole house into essentially a bomb. That gets around the pesky need for miniaturization.

[godix]

Nuclear secrets might not be about building one. Without reading the original article I dunno, but it's possible the secrets promised were about detailed specifications on delivery systems, plans on their use and/or targets, readiness, security of nuclear sites, etc. There's a lot of secrets around nuclear weapons other than how to build one.

[postcards]

Originally Posted by Whack-a-Mole

A smart high school student with the right materials could build a functional bomb but when you get into maximizing yield and shrinking overall size and such then you get to secret stuff.

Originally Posted by D18

Slightly on topic - remember the big brouhaha over the kid who supposedly designed a nuclear bomb as either a high school or university project in the 1970s? Does anyone know whether he really designed a workable weapon, or was it largely figuring things out on a more theoretical basis?

John Aristotle Phillips A junior at Princeton in 1977. And a good read, as I recall.

[GiantRat]

In high school, I gave a very simplistic lecture on how to build a fission weapons (hell - I don't understand the math still). But the atomic principle is pretty simple. My guess would be that we (and everyone else) classify this data is because of the harm it could do.

It's the weapons systems that are classified, not the theory.

[rbroome]

Originally Posted by Kinthalis

A scientist couple was recently arrested for agreeing to disclose nuclear secrets to an undercover American Agent, claiming to be a representative of Venezuela.

So I wanted to know: what exactly is so secret about nuclear weapons technology? Isn't the entire process something ANY nuclear physisist out there would know pretty well? Isn't this science out of the bag already? Are the secrets down to specific quantities/ratios of materials?

As many others have said, the "secret" of a nuclear weapon has been publicly available for decades. For a long time the "secret" of a fusion weapon (how to compress the hydrogen enough to fuse) was a secret but even that has leaked out a few decades ago. The tricky part is getting the parts together. Since you can't just order them out of a catalog, you need to know the detailed specs of what to obtain. For instance, a key component of a fusion device is a special plastic. Knowing exactly what plastic to get is the secret. In fact, if I remember correctly there was a story a few years ago where the Khan network plans were revealed and it surprised people because the technical details of some of the components were those from China. Down to part numbers. That is why his nuclear weapon plans were so dangerous. Unlike the stuff on the internet, his plans supposedly had enough detail to work. The explosive lenses are key. There are detailed descriptions of the lenses available. They have to be comprised of different explosives to form a shock wave correctly. That much is available. Ordering the right explosive and casting exactly the correct shapes is the hard part.

[Llama Llogophile]

I believe I remember reading in one of Richard Rhodes' excellent books about the Manhattan Project and the first hydrogen bombs, that certain aspects of even the earliest nuclear weapons have not yet been declassified.

The "Fat Man" type bomb had a component called an initiator, which I think may be what Rhodes mentioned.

[engineer_comp_geek]

Originally Posted by D18

Does anyone know whether he really designed a workable weapon, or was it largely figuring things out on a more theoretical basis?

The wikipedia page that postcards posted said that the weapon was not functional, but I could have sworn I read something at the time that said it had been examined by experts, who concluded that it would have worked except that it was lacking the plutonium required to make it go boom.

[Ranchoth]

The Nth Country Experiment might be relevant, here. "The experiment consisted in paying three recent young physicists who had just received their PhDs, though had no prior weapons experience, to develop a working nuclear weapon design using only unclassified information, and with basic computational and technical support.[...]The experiment ended on April 10, 1967, after only three man-years of work over two and a half calendar years. According to a heavily redacted declassified version of the summary, it was apparently judged by lab weapons experts that the team had come up with a credible design for the technically more challenging implosion style nuclear weapon."

[Kevbo]

The regulations on people with Q-clearances are fairly onerous. Two in particular made me decide I'd rather find a job that didn't need a clearance:

FCNI= Formerly classified nuclear information. Stuff that was declassified on Hazel O'Leary's watch, which the the DOE later decided was a mistake. Apparently once something is declassified, it can't then be switched back, so they created the name "formerly classified". Formerly classified info has all the same rules as classified info, but for some reason it needs a different name...or something. Nobody could ever really explain it to my satisfaction.

UCNI=Unclassified nuclear information. You can get in serious hot water for disclosing unclassified information if TPTB decide after the fact that it probably should have been classified. Yes really.

Beyond weapons technology other related stuff would be: Where are they stored? How are they transported? What sorts of security systems are in place to protect them?

[paperbackwriter]

Originally Posted by robby

1. Uranium fission bombs are relatively easy to construct, but it is very difficult to obtain and enrich naturally occurring uranium into weapons-grade U-235. It generally takes the resources of an industrialized nation to operate the centrifuges necessary to enrich the uranium. (Uranium fission bombs were so easily figured outback during the Manhattan project that the design was never even tested--the first uranium fission device ever produced was detonated over Hiroshima.)

That's half the reason. Equally-important is that, as you say, producing the U-235 was very difficult. So difficult, in fact, that there was real concern well into 1945 there wouldn't be enough for even one bomb. They couldn't have made a test U-235 weapon even if they wanted to.

[electronbee]

There was an article referenced via Slashdot that mentioned that the USA forgot how to make "Fogbank". Which is a material people can only basically speculate about.

Any ways, here are some articles about it and gives an idea of what obviously needs to be kept secret when it comes to weapons of this magnitude:

http://www.heraldscotland.com/how-th...siles-1.826976

http://www.guardian.co.uk/uk/2008/ma....greenpolitics


Also, As Bijou Drains has stated:

One quirk in US law is that even if something is already publically known, if it's still classified secret you cannot reveal it to unauthorized people.

As I was once in the military I was involved in certain actions. Despite the fact that these actions were televised in real-time or that they are on Wikipedia... "I can not confirm or deny."

[The Hamster King]

Originally Posted by Mach Tuck

The "Fat Man" type bomb had a component called an initiator, which I think may be what Rhodes mentioned.

The initiator provides a little squirt of neutrons at the moment the core reaches critical mass to kick off the chain reaction. Without an initiator a stray neutron from the environment will eventually start the reaction, but since you have a very tiny window of time before the whole assembly blows itself apart, you want to make sure the neutron cascade begins at exactly the right moment.

And, yes, I believe that initiator design is one of the things about making a bomb that is highly classified.

[JoelUpchurch]

From the article in the NY Times this morning, he also offered to show them how to build a reactor to produce weapons grade plutonium. Reactors designed to produce plutonium for weapons are different than power reactors, because weapons grade plutonium needs to be almost pure PU-239. If the reaction is allowed to run too long, then the PU-239 picks up additional neutrons and becomes Pu-240, Pu-241 etc. To much contamination and it isn't suitable for a bomb anymore. Weapons reactors have to shut down frequently to harvest the Pu-239.

http://en.wikipedia.org/wiki/Plutonium-240

[Whack-a-Mole]

Also note there is a lot of secret data on storing nuclear bombs. Apparently, due to the radioactivity, they mess themselves up in time. This is not an issue if you build one then blow it up relatively quickly but it is an issue if you plan to store the thing for years then hope to take it out of storage some years later and expect it to work.

The US and a few others know the ins-and-outs of this well from long experience. Others would have to find out the hard way too unless they stole the info so it is secret.

[Crafter_Man]

I used to work at the Department of Energy's Mound Facility, where we built components for nuclear bombs. I now work for the Department of Defense, and some of my work is for MMIII systems and nuclear subs.

For the most part, the fundamental science and physics are not secret. The actual designs are we want to protect. We have spent billions of dollars developing these systems, and we don't want this information to get in the hands of our enemies. Even seemingly mundane things like the dimensions of a copper wire are often classified.

As I've said before, the most engineered device ever built is a nuclear bomb. Few people can comprehend the amount of research, development, and testing that has been expended in this area.

[PlainJain]

Originally Posted by engineer_comp_geek

The wikipedia page that postcards posted said that the weapon was not functional, but I could have sworn I read something at the time that said it had been examined by experts, who concluded that it would have worked except that it was lacking the plutonium required to make it go boom.

The Wiki page also says that his research consisted of only publically available text but iirc he got a critical bit of info from a 3M technition regarding a material to intiate the implosion.

[TriPolar]

Originally Posted by PlainJain

The Wiki page also says that his research consisted of only publically available text but iirc he got a critical bit of info from a 3M technition regarding a material to intiate the implosion.

IIRC he was calling chemical manufacturers looking for explosives for an unspecified purpose, and one of the companies (maybe 3M) bragged that they made the explosives for US nuclear weapons.

[Llama Llogophile]

Originally Posted by Crafter_Man

Few people can comprehend the amount of research, development, and testing that has been expended in this area.

I think I could probably comprehend it. I might be surprised and impressed, but even if it were expressed in scientific notation I think the figure would be understood.

[pyromyte]

Many other countries probably have the scientists and engineers to figure the details out eventually if they have the determination, time, and money... but wouldn't it be a lot cheaper, faster, and easier to steal it?

How about using some reference material? think back to your college days, how often when working on a difficult problem would you have killed for a peak at the solution manual, even though you would have worked it out eventually?

Another thought is that, while the world's elite probably have the knowledge, there are plenty of dangerous groups out there that don't (and shouldn't).

[Bijou Drains]

Since the design for a simple bomb was completed in 1945 we can assume that there was no need for a lot of modern technology to get it working.

[Lumpy]

Originally Posted by Bijou Drains

Since the design for a simple bomb was completed in 1945 we can assume that there was no need for a lot of modern technology to get it working.

But no one today except maybe terrorist amateurs would bother with a multiton, low-yield fission device, if only because of how hard it would be to deliver. A would-be nuclear power would want something that can be delivered by missile or fighter-bomber. For another thing, if you can independently produce the fissionable material and solve the problems of building even a crude device, then you've already made enemies of the powers trying to prevent nuclear proliferation and you both need a stronger deterrent and have already done 3/4 of the work in producing a more sophisticated device.

[TriPolar]

In terms of miniaturized electronics, super-materials, and construction techniques, no. But they probably would have benefited from good computers. Many of the scientists in the Manahattan Project spent most of their time doing a lot of complicated math, with pencil, paper, and sliderules. The first plutonium bomb was an detonated with an implosion from conventional explosives, and there were questions about the reliability of the ignition process based on the available technology. The process of seperating Uranium and Plutonium isotopes for was difficult and required numerous machines and thousands of people to produce enough material for the first three bombs produced. But that part is still difficult, and one of the reasons that it is difficult to conceal the production of fissionable materials by nuclear wannabe countries.

The discussion reminds of one of the nuclear physicists I used to work with. He was a veteran of the Manhattan Project, and still did government research. He received instructions once for destroying some of the documents he kept in a government approved safe. He had a choice of several methods, but chose burning. He dumped the documents in a metal office wastebasket, took them out to the loading dock at the back of the building and ignited them. After following instructions to insure that the all the paper had been consumed, and the ashes stirred, he recruited help to roll a dumpster over to the loading dock, and kicked the wastebasket over to dump the contents. Apparently the instructions didn't mention dousing the ashes with water, or waiting until all the embers were had gone cold. The contents of the dumpster caught on fire, and drew a visit from the fire department. During this time, he had left his safe open, and just like Feynman had described in his memoirs about Los Alamos, the dial had been left on the last number of the combination. I could have used that opportunity to start stealing nuclear secrets (like the ones still in the open safe even without figuring out the combination), but I was too busy laughing about the fire.