Many people know about russian hydrogen bomb with about 100megaton projected (50 megaton tested) power.
usualy mosts sources say that it was just test device that cant be used because there was no way to deliver it, however that is not true.

But recently on russian tv I saw that it actualy was possible to use. they designed special transcontinental torpedo, which could deliver that bomb near usa shore, and explosison would be so powerfull that it could create cunami which would be able to flood all NewYork.
also there was project to make bomb ship, with so big power that explosion would result end of the world.

fortunately these projects were not finished.

No bomb that could fit in a ship with current technology can end the world, you can make one that would result in Nuclear Winter for a few years worldwide, but that is still not going to end the world...

__________________

No bomb period with modern technology could end the world, in fact no number of bombs with modern technology could end the world. At most we could make a few minor dents in it, but the power levels needed to end the world are far beyond anything we could hope to accomplish with modern, or even forseeable, technology.

__________________
I met this wonderful girl at Macy's. She was buying clothes and I was putting Slinkies on the escalator.
-Steven Wright



My Website: The Black Cat's Web Page

I think you are talking about destroying Earth it's self, I mean just to destroy life...which is well within our reach, especially during the Cold War...

__________________

TheBlackCat. Actually, I'd disagree here. A nuclear weapon is used to initiate a thermonuclear weapon. Because of geometrical/isotropic purity constraints...there is a limit to the yield of a nuclear weapon. But there is no limit to the second step....other than economics. A large collection of wealthy zealots poses a huge risk. H-bombs could be constructed to remove large portions of the surface of the Earth...not just cities, but small countries...hence our understandable vigilance with regards to step 1....
With all due respect, Pete.

__________________
A third rate theory forbids.
A second rate theory explains after the fact.
A first rate theory predicts.
A. Lomonosov

Hardly. Multicellular life MAYBE, but even that is unlikely. We could easiley destroy ourselves, but even wiping out a single phylum, not to mention 3 entire kingdoms, has proved to be extremely difficult no matter how much destruction our planet sustains.

Earth has been through events far worse than anything we could hope to achieve, yet life has still come back. Even if we somehow managed to wipe out 90% of the multicellular species on Earth, which I find very unlikely, we would only be looking at an End Permian level event, which although it is the worst our planet has seen life still bounced back relatively quickly. The KT event alone was hundreds of times the explosive power of our entire nuclear arsenal, yet it was one of the least destructive mass extinction. It only destroyed about 50% of Earth's species. Surely a terrible event, but it came no where close to wiping out multicellular life on the planet, not to mention all life.

__________________
I met this wonderful girl at Macy's. She was buying clothes and I was putting Slinkies on the escalator.
-Steven Wright



My Website: The Black Cat's Web Page

Even so, life would go on. We probably wouldn't make it, but life in general has suffered far worse many times in the past and come through just fine (albiet radically different). The worry isn't about life in general surviving, that is a given, the worry is us surviving.

__________________
I met this wonderful girl at Macy's. She was buying clothes and I was putting Slinkies on the escalator.
-Steven Wright



My Website: The Black Cat's Web Page

Let's content ourselves with worrying about the future of human life. Other forms of life can fend for themselves, and probably exist on countless other planets as well. We have enough on our plates to try and keep ourselves alive, which I feel is certainly a valid goal for humanity. If we possess weapons that are capable of ending all human life, that is an important watershed event, and not a good one.

To put this in perspective, I once asked a class of 20-year-olds what people worried a lot about in the 60s. What kept people up at night in the 60s, more than anything else? They had absolutely no idea. Food for thought.

of course it is hardly possible to vaporize earth, but not so hard to destroy most of high foms of life. H bonb have no power limit, components are insanely cheap, and available in unlimited amounts. So it is not so hard to make 1 or more gigaton bomb.

The worst thing is to imagine such thing in the hands of suicide bomber.

KT was ONE pinpoint spot of destruction, but strategically placed bombs placed in thousands of places around the world would certainly kill all multicellular organisms on earth from a collaboration of fallout, nuclear winter, and the collapse of the food chain...other then things like bacteria life would be done for earth...at least for millions of years, and by the time it built it's self back up strong, the sun will boil away all the water on earth, destroying ALL LIFE FOR GOOD, including the single celled organisms.

__________________

That timetable might be overly pessimistic. The Sun should remain conducive to life on Earth for a few more billion years, and since I agree that millions of years are all that is needed to build up complex organisms, I agree with TheBlackCat that life would reappear after a nuclear holocaust. However, there's no guarantee it would ever approach the intelligence of humans, an ironic concept in that scenario anyway.

Actually, this is not even close to being true. The H-bomb limit was pretty much reached with the Soviet Union's Tsar bomb, which was only tested at 50 MT, with the theoretical possibility of 100 MT. The cost was prohibitive and the effect was less than desired, aside from perhaps the political one. With advances in precision striking capability, large MT nuclear weapons research was fazed out for MIRV technology (multiple independently targetable re-entry vehicle), which allows a single missile to now strike many targets at once.

A GT (gigaton) yield weapon is not possible at all. The problem with the Tsar bomb is that it was too big and the Soviet Union had problems with making all the of material create the fusion explosion before it was dispersed and unable to continue adding to the explosive yield. It was estimated that about 25% of the bomb would be wasted at the 100 MT range from the results of the 50 MT test. The bomb was also so heavy that it would only be able to be carried by the largest bomber in the USSR air force and was not able to be delivered by ICBMs.

Terrorists have no chance of using even MT-range nuclear weapons, they are far too heavy and require ICBM or bombers for delivery. It may be possible for a terrorist to obtain enough material of a low yield KT (kiloton) device, but even this is highly unlikely. A terrorist could never get enough nuclear material to produce a single MT nuclear weapon. It would be possible to build a KT (kiloton), but the amount of material required as well as the technology and expertise needed makes it very unlikely.

The main concern would be the "dirty bomb," which is nothing more than a regular explosive device with some radioactive material added in that will disperse over a heavily populated area. While certainly a concern, this is not a nuclear weapon, nor would it add to the explosive capability of the device in question. It would, however, make a large area uninhabitable due to the radioactive fallout and would require an evacuation of the area.

__________________
DOOM Master

100MT was not limit, this desiwn was just proof that there is no limit on nuclear power anymore. And since deuterium is quite cheap, as well as depleted uranium used for amplification, the cost is very low.

delivery is not problem either, submarine or torpedo, or just simple ship an do tha esily. of course that will be suicidal mission. gigaton range weapon probaly do not require delivery at all. in any case all humanity will die, no matter where is location of explosion.
these kind of wepons are not for attack but for defense from inteligent life forms. unfortunately and fortunately terorists dont count being inteligent, so they cant make such things, and nobody is going to make them for sale.
Original usage was simple, if we die we will destroy all earth. but as I see that is fine for suicide bombers.

Anyway with today technology and knowledge is quite trivial to make nuclear weapons, plutonium enrichment can be made even at home, however th bigest problem ir to stay alive while you do that, and pay the bills for electricity. also raw materials are not possible to get easily. but if you own nuclear reactor that is no problem.

I think the terrorist threat of nuclear weapons may be under-estimated. There are some claims that even reactor grade uranium and plutonium could be made into nuclear bombs. They would not be efficient, but they could yield up to a kiloton, more than enough to take down one or more skyscrapers.

As for large bombs, there is really little reason to do it. I'm not sure that it is impossible to make a one gigaton bomb... maybe a modified layercake multistage device could eventually deliver a yield that large through a series of steps, but I doubt it. It's more destructive to use several smaller bombs than one large bomb.

Even then, I don't think we'd actually be able to destroy all multicellular life on the planet directly. With a 5psi overpressure blast radius for a 200-kt airburst we'd need almost 1 million devices to blast every square mile of US territory. With a 500-KT airburst we'd need over half a million devices. With a 1-MT airburst we'd need over 338-thousand devices. Of course, animals burrows that are more than a few feet underground will survive at dramatically closer radii.

The above used a 5psi overpressure, but the published overpressure lethality threshold (not from impact from or against objects) for humans is actually 10psi. The radii for 10psi are: 2.8mi for 1MT, 2.2mi for 500KT, and 1.6mi for 200KT.

Radioactive fallout is harder to figure because you need to take into account the type of device, the yield, the location of the explosion, the winds and weather, the biology of the individual species, the time since the explosion, the area of deposition, the amount of time spent in the radioactive zone, the decay rate of the fallout and any mass shielding the animal might have from its habitat. Due to the shielding ability of water, it's unlikely we could ever kill off ocean life.

__________________
"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

The most powerful bomb detonated was the Tsar Bomba(Ivan)...with a 57 megaton payload.

The original plans called for 100MT, but was scaled down to reduce fallout.

__________________

uranium is more safe to work, but requires too much mass for bomb, plutonium requires very little mass, for example if you use magnetic separator, then you can make either 5 uranium bombs per year, either 100 plutonium bombs. so it is actualy quite easy, if you have plutonium.

The most dangerous weapon in the world is Stupidity.

So easily produced and distributed.

So many possibilities.

In theory it is possible to build larger bombs. In practice, it is likely that practical problems would crop up.

Why would all humanity die? The energy of the 2004 tsunami was about .8 gigaton. Assuming the energy of a nuke could be coupled as efficiently to the ocean (which isn't a given) I would expect similar results. Not nice, certainly, but not the end of humanity.

As a rule, bigger bombs are less useful. In the early days, rockets had decent payload capacity but horrible accuracy, so larger bombs were used to compensate. But the destruction radius from a 10 megaton bomb is not nearly 10 times that of a 1 megaton bomb and the same holds true with a 100 megaton bomb.

Whoa! Now you've gone from theoretical bomb designs to terrorist nukes. Building a first generation fission bomb is tricky enough. Building a sophisticated multistage thermonuclear device is much, much harder.

Uh, no.

Uranium enrichment requires very large scale industrialization. This may be possible for a government, that's about it.

For plutonium, you have to build a reactor, you have to process the fuel properly, and it still takes time. The industrial scale is somewhat less than uranium enrichment, but by no means small.

Then you have to build the bomb. A first generation plutonium implosion device is more difficult to build properly than a U235 gun design. A first generation design also is unlikely to be frugal with material.

This is all far from easy.

__________________
I say there is an invisible elf in my backyard. How do you prove that I am wrong?

Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

The isotope mix is the issue. One thing is certain: A bomb made with something like reactor grade uranium would be much more difficult to build. It is far from a first generation design.

__________________
I say there is an invisible elf in my backyard. How do you prove that I am wrong?

Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

well, i probably over estimated the end of world if that cunami was 0.8 gigaton however nuclear winter could be real problem.

enrichment is quite trivial to do, all you need is lots of elecricity, i think best is magnetic ion, or gell separation, centrifuges take too much space, and produce poor and unpredictable results.
magnetic separator can easily make almost completely pure isotopes no matter what initial mixture was. this will not work with uranium, ulness you have personal power plant to power that magnetic separator.

I don't think it is a first generation design, but it might be a more likely design since RGU is probably easier to come by than HEU. Heck, I handled RGU pellets in middle school.

__________________
"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

For uranium, you need to use isotope enrichment. No matter what scheme you use, it takes a lot of space (think of a small city). Magnetic isotope separation also takes a lot of power.

It is a problem with plutonium too.

If you have a reactor designed for the purpose you can chemically separate the plutonium. That still is a major operation, but no isotope separation required, though you will be stuck with the implosion design.

If you have plutonium that has been sitting in a reactor for a long time, you have a problem. You want 239Pu, but there will be a lot of 240Pu, which has a high spontaneous fission rate. That means it is hard to get a good explosion out of it, because you can't keep the plutonium together for long - it will tend to predetonate. This is also why even conventional plutonium bombs require an implosion design (a pure 239Pu bomb could probably be built with a gun design).

Both 238Pu and 240Pu are bad. They are hot, literally. That means you need an active cooling system for the bomb.

Note that the stuff you want is in the middle, and it is only one AMU away from 238Pu or 240Pu. That makes it much harder to separate than 235U from 238U (three AMUs apart). Also, this is mass based, if you are trying to exclude 240Pu, you will concentrate 238Pu along with 239Pu. 238Pu will be concentrated better than 239Pu because of the lower mass.

Along with that, there is no "nice" gas equivalent to uranium hexafloride, and this stuff is nasty (radioactively hot).

The U.S. considered a multibillion dollar program for plutonium enrichment. Laser enrichment was a leading contender (which would require a lot of R&D). They didn't go through with it because there wasn't sufficient need and they didn't want to develop the technology, opening the door to some other government sneaking away with the tricks.

I'm not aware of anybody doing large scale plutonium enrichment. It is just too hard. There are easier options, though they aren't easy options.

__________________
I say there is an invisible elf in my backyard. How do you prove that I am wrong?

Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

tahat is what I say magnetic separation requires lots of power, but quality is ideal. no mater how contaminated plutonium is you will have perfect separation in one pass. and since only tiny amount is required electricyty cost for few bombs will be not too high, but of course much higger than military equvivalents.
having perfect plutonium with better grade than military, you can make quite good bomb. as I know if you use neutron reflector you need only 3kg of plutonium instead of 30kg uranium, so the bomb will be tiny too. as I know smalest military designs are about 50kg or little less. with 0.5-2 kiloton power.

magnetic separator does not require much knowledge to build, and produces perfect results as I know at least 99.9% purity. so it is best choice for small scale production.

I believe an emphasis should be on "claims".

From what I know of nuclear technology, the reactor grade uranium and plutonium is far too low to be used in a fission device. Reactor grade is normally between 3-5%. Weapons grade is at 90%.
The most they could do with the material is make a dirty bomb.

__________________
This is no fantasy. No careless product of wild imagination. - Jor-El

Godspeed, John Glenn. - Scott Carpenter

And these atomic bombs that science burst upon the world that night were strange even to the men that used them.
- H.G Wells, The World Set Free

To the conspiracy crowd, radiation is a big Boogey Man that inspires terror and death in all who encounter it. - JayUtah

For plutonium grades such as "fuel grade", "reactor grade", "weapons grade" etc. are defined by the proportion of Pu240 which the material contains.

This page lists the cutoff points for the various grades. It also mentions an announcement from the Secretary of Energy in 1994 that the USA had successfully tested a bomb design using reactor grade plutionium back in 1962.

One caveat: I've read (though I don't have the reference handy) that the definition of "reactor grade" wasn't the same as that in use today, and that the Pu used in that test was closer to the modern weapons grade than the name implies.

__________________
Please enjoy your trip through this door.

Note about the "gun-type" A-bomb, which would be easiest to build:

Correct me if I'm wrong, but I've read that even such a simple device would blow itself apart after implosion--before full fission potential was reached--if it weren't explosively compressed enough, which means the actual yield would be far below the theoretical one.

__________________
"Call me old-fashioned, but I think fire is magic. And it scares me a lot."

--The State

Gun-type is usually used for uranium because of uranium's lower insertion speed requirement. The main goal of the gun-design is to assemble a critical mass of fissile material quickly enough for it to use the entire mass in the fission process. I'm not sure if compression is as important to uranium yields... I'd have to re-read some things. I think it might help when using lower grades of material. However, the main use of uranium these days tends to be in post-primary stages where the higher efficiencies of Pu initiations generate conditions that create higher efficiencies in the Uranium tampers.

I do remember that plutonium responds more quickly meaning it will predetonate in a gun-type of insertion device. However, a similar type of plutonium design uses linear implosion along a single axis to compress the Pu to a supercritical state. The efficiency is not as high, but it will yield a nulear explosion. Linear implosion of Pu is what is used in most nuclear artillery shells because of the slimmer diameter requirements.

Grand Lunar, did you read that link and the linked PDF? I think they were written by nuclear physicists.

__________________
"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Yes, I did read it. One needn't be a nuclear physicist to write it, though. With proper research and understanding, one can write such an article.
Ktesibios's post gave me more insight into the particulars of plutonium that I never knew (I was just familar with uranium).

Still, despite all this, I believe it is not as easy for terrorists to manufacture their own nuclear devices as is believed. It is more expensive that one thinks, and more involved. You need many people that really know what they are doing to preform such a task.

__________________
This is no fantasy. No careless product of wild imagination. - Jor-El

Godspeed, John Glenn. - Scott Carpenter

And these atomic bombs that science burst upon the world that night were strange even to the men that used them.
- H.G Wells, The World Set Free

To the conspiracy crowd, radiation is a big Boogey Man that inspires terror and death in all who encounter it. - JayUtah

The most powerful weapon in the world is a genius, with both a unlimited desire for power and an excellent feeling for demagogy

__________________
Quid est ergo tempus.
Augustinus

Please provide references to this amazing process. The only magnetic enrichment method I'm aware of requires many passes and would preferentially concentrate 238Pu. That's assuming you could overcome the practical problems in the process, like not having a decent gaseous medium, and that the hardware will have to be remotely operated (it will get radioactively "hot").

Not that tiny, and as I noted before, nobody is doing plutonium isotope enrichment precisely because it is so hard.

3kg is very small for either U235 or plutonium. Fancy design with neutron reflectors and tritium can reduce the mass somewhat, but that isn't a first generation design either. The general outline is one thing - that's public information and what we're discussing here. Getting the details right is a different ballgame.

Again, please provide references to a documented method of large scale and efficient plutonium isotope enrichment. "Large scale" meaning many kilograms, not microgram quantities.

__________________
I say there is an invisible elf in my backyard. How do you prove that I am wrong?

Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser