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Deterrence

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Re: Deterrence

Postby shiv » 28 Feb 2017 08:08

ShauryaT wrote:(till US, Russia and China have this MT fetish)

Shaurya other than Karnad whose word I do not trust on this - have you any sources that point to a megaton fetish? Because all the newer references I read suggest that what you term a megaton fetish is gone and the world has moved on. The US openly speaks of newer weapons of lower yield with the remaining megaton weapons being the oldest weapons and oldest designs waiting for end of life. Russia and China are opaque but China tested very few megaton weapons - maybe just one of 4 megatons in the 60s or 70s. Then in the 90s when China and France tested again China just did tests which were in the 90-100 kt range. France to did not do any "megaton validation"

The US will retain some megaton capability but calling it a fetish is rhetoric aimed at convincing the reader that you have facts that he should swallow unverified. I need to see something better than that.

I repeat yet again that the world has actually moved into a "post MAD" era. MAD or mutually assured destruction worked only because everyone in the game understood that fallout would ensure that you die along with your enemy. What is happening now is an emphasis on accurate lower yield weapons that ensure pinpoint, painful damage and less fallout. This is where the world is headed and I stick my neck out on this and am willing to take on any "strategic experts" of the Karnad ilk on this issue.

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Re: Deterrence

Postby shiv » 28 Feb 2017 08:28


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Re: Deterrence

Postby Manish_Sharma » 28 Feb 2017 08:33

Unfortunately whether we test or not can only be discussed on "deterrence" thread. So naturally anyone arguing for test can be condemned - labled as Dhoti-shiverer.

Beyond Deterrence there is actually war where nuke bombs will be just like other bombs.

WHETHER YOU CAN SEND THE ENEMY IN PASHAN YUGA WHILE HE CANNOT DO THAT TO YOU MATTERS. MORE TESTING WHICH GIVES MORE WARHEADS IS NEEDED.

Safer warheads for submarine also need testing.

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Re: Deterrence

Postby ShauryaT » 28 Feb 2017 09:07

Shiv ji: The total tonnage of MIRV on a single carrier is still in MT for the major powers. It has simply moved from one single big MT to a more efficient model, where the net tonnage of missile has actually become higher. Reducing CEP's has actually allowed for this. To achieve a level of say "medium" level of destruction over an area, say the size of Shanghai would require just about 2 US Trident missiles. Each missile would yield a destructive power of about 5 MT. Each warhead about 475 KT. 8-12 n warheads on each missile. The mainstay of US, Russia and not public information yet, but I will bet that China will replace its 3+MT warhead on DF-5 with an equivalent or more total yield on its MIRV DF-41.

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Re: Deterrence

Postby shiv » 28 Feb 2017 09:21

ShauryaT wrote:Shiv ji: The total tonnage of MIRV on a single carrier is still in MT for the major powers. It has simply moved from one single big MT to a more efficient model, where the net tonnage of missile has actually become higher. Reducing CEP's has actually allowed for this. .

OK now you are acknowledging science while moving the goalpost

Multiple bombs of lower yields in kilotons are as destructive as megaton bombs. I have been saying exactly this all along.

I deliberately used the 20 kiloton analogy because multiple 20 ton bombs are really as dangerous as a megaton bombs. You may be more afraid of Chinese megatons but I am equally afraid of Pakistani kilotons

In fact just 4 x 100 kiloton devices gives you a megaton worth of damage.

Once again I refer you to the well worked out tables that show that 6 x 50 kiloton bombs will do nearly as much damage as a 1 megaton device and can be used in pairs or threes for smaller towns based around military installations. So what was that again about "megaton fetish" when you are yourself saying that kilotons add up to megatons?

In the table, Increasing bomb yield by 40 times increases damage only by 11 times. The bigger the bum the less efficient the damage and the more the stuff you release into the atmosphere.

Image

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Re: Deterrence

Postby kit » 28 Feb 2017 09:53

Well the NK was able to get to their football warhead with just a few tests !!! .. why would any one think that India with its vastly superior resources cant do better with the shakti 2 :evil:

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Re: Deterrence

Postby ShauryaT » 28 Feb 2017 09:53

To destroy Shanghai, you can do so with 5 missiles of 3 MT yields or 2 MIRV missiles, yielding a total of 10 MT on 20 warheads. In either of the cases MT levels of yields is unleashed to achieve the needed levels of destruction. The latter is simply more efficient. Now you can argue that one can do so with a 100 missiles of 100 KT each or maybe just 20 missiles of 100 KT is sufficient or maybe just one with 20 KT is enough to deter. There is an optimal level of efficacy on costs and risks to wield a certain number of missiles, warheads and yields. The best practice seems to be about 8-12 MIRV, each about 300-500 KT. At the end of the day, MT levels of yields is unleashed to achieve the desired levels of destruction.

There does remain a small case of MT levels of warheads to get to hardened silos built to withstand a certain threshold of PSI.

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Re: Deterrence

Postby shiv » 28 Feb 2017 10:06

ShauryaT wrote:To destroy Shanghai, you can do so with 5 missiles of 3 MT yields or 2 MIRV missiles, yielding a total of 10 MT on 20 warheads. In either of the cases MT levels of yields is unleashed to achieve the needed levels of destruction. The latter is simply more efficient. Now you can argue that one can do so with a 100 missiles of 100 KT each or maybe just 20 missiles of 100 KT is sufficient or maybe just one with 20 KT is enough to deter. There is an optimal level of efficacy on costs and risks to wield a certain number of missiles, warheads and yields. The best practice seems to be about 8-12 MIRV, each about 300-500 KT. At the end of the day, MT levels of yields is unleashed to achieve the desired levels of destruction.

There does remain a small case of MT levels of warheads to get to hardened silos built to withstand a certain threshold of PSI.


Shaurya you are now firmly moving the goal post from "Megatonne warheads" of Karnad to your own beliefs. That is OK as far as I am concerned

PSI on target is about height above target and accuracy. That PSI could even come from a 50 kiloton weapon placed accurately and even 10 megatons taking out 120 sq km will not be much on 1600 sq km Shanghai. Rhetoric is easy. Specifics need fleshing out. What are you talking about when you say "needed level of destruction" . These are empty words that need to be qualified. What is needed level of destruction?

But I would prefer it if you could discuss what you mean by damage to a city and what you mean by megatons to get adequate PSI . We can talk but I will not take fudging

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Re: Deterrence

Postby sudeepj » 28 Feb 2017 23:36

shiv wrote:
ShauryaT wrote:Shiv ji: The total tonnage of MIRV on a single carrier is still in MT for the major powers. It has simply moved from one single big MT to a more efficient model, where the net tonnage of missile has actually become higher. Reducing CEP's has actually allowed for this. .

OK now you are acknowledging science while moving the goalpost

Multiple bombs of lower yields in kilotons are as destructive as megaton bombs. I have been saying exactly this all along.

I deliberately used the 20 kiloton analogy because multiple 20 ton bombs are really as dangerous as a megaton bombs. You may be more afraid of Chinese megatons but I am equally afraid of Pakistani kilotons

Image


The goal in using these weapons is to get the energy released by them in a flat kachori/idli like shape instead of an apple like shape. Smaller weapons are useful for this compared to the multi megatonne types. So why the radiation implosion designs with MT or 100s of KT range yields instead of boosted fission ones?

Because:
1. The amount of fissile material, which is the limiting factor in the number of weapons you can deploy, used in radiation implosion weapons is much smaller than the amount used in fission or boosted fission weapons. Most modern 100-300KT weapons will use the same/similar amount of Pu as the first bomb dropped on Nagasaki.

2. You could build a 100KT fission or boosted fission weapon, but the size of the explosive lenses required to achieve a good compression in the pit will be much larger, because the size of the pit is also large! So you would not be able to fit in as many weapons on a missile! There is a downward spiral in capability, much like weight increase in aircraft.

3. A 100-300KT radiation imploded weapon may have a small boosted primary of 5KT (which would yield a sub KT amount of energy without boosting) and a secondary that uses another few pounds of Pu. The dimensions and the weight of the device are determined by the size of the primary. A 20 KT or so fission or boosted fission device would be much larger with consequent effects on your missile capability.

4. Ultimately, the game is to get the most amount of energy released in a kachori shape with the least amount of Pu. Radiation imploded weapons are the best known way of doing this. Sure, you could get the same amount of energy released using KT boosted fission weapons, but you will need many more of them, and many more missiles compared to the radiation imploded thermonuclear designs.

5. Using 100KT-300KT (or MT) designs allows you to kill the entire population of a city (a genocide!) using just one missile with multiple warheads. You can not do this using fission or boosted fission only weapons, you will need perhaps an order of magnitude more missiles and Pu.

6. A mistake is being made in running mental scenarios that correspond to KT strikes in peacetime. Wartime efforts will obviously be different and a populace mobilized for wartime will have very different reactions compared to peacetime. An example of thousands of burn victims is given and a comparison is made with the medical facilities available. But the counter point is, that in the absence of such facilities, serious burn victims will simply die of infection/shock etc. in a week or so making the task of providing care moot. In the meantime, spare capacity will be mobilized from neighboring areas.

7. Simple efforts such as accessible trenches, a few minutes of fwd. warning, and food stuff stored for a week will afford people a much better chance of withstanding a nuclear strike. People in cities that could be bombed in 1971, such as forward airbases (Jodhpur, Jaisalmer, ...) did dig trenches and they did spend their nights in them when the air raid sires went off. In a populace mobilized such as this, the extent of injuries will be much lesser, i.e. people will be either dead or not so seriously injured.

8. A city can recover in the months and years ahead after a KT strike that kills or incapacitates 15% or so of its population. On the other hand, a MT strike (or three 100KT warheads) will kill a much larger fraction of that city and make its recovery impossible. The politicians will be dead, the cultural elite will be dead, the bureaucrats will be dead, the police will be dead, the educators will be dead.. and so on. A few well aimed strikes can even put the survival of an entire nation at stake.

We also need to look beyond mere deterrence. As India grows in power and wealth and its people become ever more connected, the senseless acts of terror become even more unbearable than before. I cant see an India of 2020 go through a proxy war such as the one we faced in 99-2002 time frame without a full scale war erupting. We need to understand compellance and how relative nuclear arsenal sizes factor into this.
Last edited by sudeepj on 01 Mar 2017 00:10, edited 1 time in total.

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Re: Deterrence

Postby ramana » 28 Feb 2017 23:59

When you say kachori, you mean kasta kachori(KK) type and not regular spherical kachori (K)?
KK will cause a more directed blast with less up blast.

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Re: Deterrence

Postby sudeepj » 01 Mar 2017 00:08

ramana wrote:When you say kachori, you mean kasta kachori(KK) type and not regular spherical kachori (K)?
KK will cause a more directed blast with less up blast.


Haha.. :rotfl: In the north, kachori is flattish.. spherical kachoris were a novelty for me when I first saw them.

May be a 'fulka' or 'bhatoora' or 'idli' shape is a better analogy.. I dont know of spherical idlis :-D

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Re: Deterrence

Postby ShauryaT » 01 Mar 2017 02:49

SudeepJ: Thanks for that post above.

Shiv ji: A little tied up but no goal shifting from my end or fudging. My position on this has been long set. The evolution of city busters being MT level weapons, done from a single warhead or MIRV is an evolution of CEP and a need to be efficient. Bottom line is MT levels of destruction is essential. I will elaborate later. Do not think Karnad's position is any different from mine on this but can qualify and get back. Thanks.

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Re: Deterrence

Postby disha » 01 Mar 2017 04:16

I see my post removed., but when people talk about pits & pu etc., they forget one important aspect - the triggers.

A High Explosive blast travels at the speed of say 8-10 km/sec. Taking the upper limit 10000 m/sec. or in 1-millisec it travels 10 meters. And hence the switches need to be faster than microseconds. Since even in a microsecond, the detonation travels 1/100 th of a meter or 1 cm! Imagine one switch is off by a microsecond and one immediately has a fizzle.

Size of the bum is not measured by the amount of plutonium you have in the pit., but the amount of fission you can accomplish in a shortest unit of time. Hence the quest is for nanosecond or femtosecond switches. And of course the fastest detonation velocities.

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Re: Deterrence

Postby shiv » 01 Mar 2017 09:42

sudeepj wrote:
3. A 100-300KT radiation imploded weapon may have a small boosted primary of 5KT (which would yield a sub KT amount of energy without boosting) and a secondary that uses another few pounds of Pu. The dimensions and the weight of the device are determined by the size of the primary. A 20 KT or so fission or boosted fission device would be much larger with consequent effects on your missile capability.


Megaton weapons were created for maximum damage and were maximally dirty because most of the yield came from fission of tamper. Modern weapons of the 100-300 kt range have apparently (according to the same sources you and I are finding on Google) have removed the differentiation between so called "thermonuclear" and "boosted fission" because those yields are perfectly feasible in boosted fission and Uranium availability (except for India?) is not a problem any more. I am sure you can Google the refs that say this

sudeepj wrote:5. Using 100KT-300KT (or MT) designs allows you to kill the entire population of a city (a genocide!) using just one missile with multiple warheads. You can not do this using fission or boosted fission only weapons, you will need perhaps an order of magnitude more missiles and Pu.

This appears to be your conclusion. Nowhere does it say anything of the sort. Lots of references say that boosted fission becomes problematic (warhead too big) for yields above 300-400 kt. TN is better for higher yields. Please check and post soucres for your conclusions. There is a lot of new info now in the same sources that I read thoroughly 6-7 years ago and like everyone else on this thread I have also been busy Googling and confirming things before saying anything

sudeepj wrote:6. A mistake is being made in running mental scenarios that correspond to KT strikes in peacetime. Wartime efforts will obviously be different and a populace mobilized for wartime will have very different reactions compared to peacetime. An example of thousands of burn victims is given and a comparison is made with the medical facilities available. But the counter point is, that in the absence of such facilities, serious burn victims will simply die of infection/shock etc. in a week or so making the task of providing care moot. In the meantime, spare capacity will be mobilized from neighboring areas.

This is where I believe you have either not read or are unaware of disaster management. Or even what a disaster entails. When you have 100,000 rotting bodies in one area and 200,000 or more refugees and relatives - most of them wounded pouring out into surrounding areas and dying on the streets there the "spare capacity" of the neighbouring areas to function normally will be disrupted. Dogs, vultures and flies will pour in from surrounding areas to do their bit. Even if it is decided that "This is wartime, we will let the nuked area remain as it is" - the theory is easier than practice. There will be transit power and other utility lines in the nuked areas that require repair. If they cannot be accessed. it will affect other areas. Service people and migrants - waiters delivery boys, small time vendors, people with relatives in other towns will want to move out leaving businesses paralysed. Factories, schools. colleges and businesses will close. Relatives of people in affected areas from surrounding areas will be in a sate of panic wanting information. it is possible to write a book on this but references are available for those who are interested.
sudeepj wrote:8. A city can recover in the months and years ahead after a KT strike that kills or incapacitates 15% or so of its population. On the other hand, a MT strike (or three 100KT warheads) will kill a much larger fraction of that city and make its recovery impossible.

This is simply an assumption. One 15-20 kt bomb killed about 100,000 and wounded 200,000 in Hiroshima.

A city that has just two bombs dropped on it will lose too many people to function in the short to medium term. But a large country can survive if one city goes. if 50 cities get hit by 2 x 20 kiloton bombs each - that country will not be in a position to continue normal function. I deliberately use the 20 kt example because that is bad enough. If you have higher yields it is OK but one needs to nuke at least 25 to 50 cities. The yield matters less than the fact of disrupting the cities.
Last edited by shiv on 01 Mar 2017 10:13, edited 2 times in total.

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Re: Deterrence

Postby shiv » 01 Mar 2017 09:58

Information relevant to this discussion. I will make another post (indicating that I have been reading) about the part that I have highlighted in red below :D
http://nuclearweaponarchive.org/Nwfaq/Nfaq4-5.html
Highly enriched uranium is definitely known to be used in U.S. weapons. About half of the U.S. inventory of weapons-associated HEU is less than "weapons grade" (<93.4% that is). The probable use of most or all of this uranium (generally with an enrichment of 20-80%) was in thermonuclear weapon tampers.

The W-87 Peacekeeper warhead (to be redeployed on the Minuteman-III) has a current yield of 300 kt, that can be increased to 475 kt by adding a HEU sleeve or rings to the secondary. Whether this represents an actual addition to the existing secondary, or whether it replaces an existing unenriched sleeve is not known. The W-88 Trident warhead is a closely related design, and has a current yield of 475 kt indicating that it is already equipped with this addition. The 175 kt yield difference amounts to the complete fission of 10 kg of U-235.

Now, once one considers using substantial amounts of HEU in the secondary, the question of why the fusion fuel is needed at all arises. The answer: it probably is not essential. The idea of imploding fissile material is what set Stanislaw Ulam on the path to that led eventually to thermonuclear weapons. But with the availability of large amounts of HEU, and the trend toward smaller weapon yields (compared to the multimegaton behemoths of the fifties), the Ulam's idea of using radiation implosion to create a light weight high-efficiency pure fission weapon returns as a viable possibility. It is an interesting question whether all modern strategic nuclear weapons *are* in fact thermonuclear devices!

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Re: Deterrence

Postby sudeepj » 01 Mar 2017 10:12

disha wrote:I see my post removed., but when people talk about pits & pu etc., they forget one important aspect - the triggers.

A High Explosive blast travels at the speed of say 8-10 km/sec. Taking the upper limit 10000 m/sec. or in 1-millisec it travels 10 meters. And hence the switches need to be faster than microseconds. Since even in a microsecond, the detonation travels 1/100 th of a meter or 1 cm! Imagine one switch is off by a microsecond and one immediately has a fizzle.


So far, so good.

disha wrote:Size of the bum is not measured by the amount of plutonium you have in the pit., but the amount of fission you can accomplish in a shortest unit of time. Hence the quest is for nanosecond or femtosecond switches. And of course the fastest detonation velocities.


But you lost me here.
1. Assuming all the detonators go off as expected, the amount of the boom depends on the inward momentum/inertia of the {tamper+neutron reflector+Pu/U} sphere trying to keep the assembly intact and the energy released by the fission trying to blow the assembly apart.
2. (Other things being equal, namely, the timing/number of the initial neutrons released and the presence of boosting) The bigger and stronger the shock wave, the longer the assembly stays together and the bigger the boom. Particularly so, because most of the energy released is in the last few generations of fission.
3. E.g. Davy Crocket uses a lot of Pu (I remember more than twice the amount in fat man, but cant find the reference handy), and very small amount of explosives, and consequently, a tiny yield.

Learning about this as I go, so may be there are gaps in my understanding.

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Re: Deterrence

Postby disha » 01 Mar 2017 13:43

SudeepJ., it is not the inertia of the tamper+neutron reflector+Pu in the sphere., it is the number of Pu atoms fissioned in the first population.

Since one starts with a smaller population of Pu fissions., the eventual population of fissioned atoms will be exponentially smaller compared to a perfect condition.

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Re: Deterrence

Postby disha » 01 Mar 2017 13:48

shiv wrote:A city that has just two bombs dropped on it will lose too many people to function in the short to medium term. But a large country can survive if one city goes. if 50 cities get hit by 2 x 20 kiloton bombs each - that country will not be in a position to continue normal function. I deliberately use the 20 kt example because that is bad enough. If you have higher yields it is OK but one needs to nuke at least 25 to 50 cities. The yield matters less than the fact of disrupting the cities.


One must also not discount the fact of ports & hospitals & supply centers & other infrastructure knocked out causing further grid lock and exacerbated with population masses wanting to be evacuated and population masses wanting to be saved and masses of support infrastructure moving in to provide succor. Without any supporting utilities electricity, roads, water, food etc.

Add to it complete breakdown of law & order and governance.

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Re: Deterrence

Postby JohnTitor » 01 Mar 2017 18:57

shiv wrote:This is simply an assumption. One 15-20 kt bomb killed about 100,000 and wounded 200,000 in Hiroshima.

A city that has just two bombs dropped on it will lose too many people to function in the short to medium term. But a large country can survive if one city goes. if 50 cities get hit by 2 x 20 kiloton bombs each - that country will not be in a position to continue normal function. I deliberately use the 20 kt example because that is bad enough. If you have higher yields it is OK but one needs to nuke at least 25 to 50 cities. The yield matters less than the fact of disrupting the cities.


This is a good video that explains the numbers. In summary, humanity can be made extinct by as little as 300 1.2mt.


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Re: Deterrence

Postby shiv » 01 Mar 2017 19:14

JohnTitor wrote:
This is a good video that explains the numbers. In summary, humanity can be made extinct by as little as 300 1.2mt.

This post actually pre-empts (or serves as an introduction to) a post I was going to make. This is the problem with nukes - how many nukes can be used in anger before they kill you. I am not actually going to answer this question but will a post about what I thought was a very fascinating history of US nukes - relevant to what we have been discussing. The post will help me remember, and hopefully someone will find it interesting.

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Re: Deterrence

Postby shiv » 01 Mar 2017 20:02

This post is a bit of history - I want to put it down before I forget and have to re read.

After the Soviet Union exploded its first nuke US scientists (in a secret project) hoped to make what they called the "superbomb"

The original "classical" superbomb was going to be a fusion bomb and it was hoped that fusion fuel could be "lit up" to burn up and make a bomb that would be 1000 times more powerful than the Hiroshima bomb. But there was a huge problem. Fusion fuel - i.e Hydrogen in its Deuterium and Tritium avatar does not "burn". It "burns" in the sun, can't be made to do that easily on earth. Calculations showed it to be an insurmountable problem and it was simply not going to happen.

In order to counter the USSR scientists fell into two groups. One group included Oppenheimer and many others including Enrico Fermi. Oppenheimer in particular was later accused (by Teller) of being anti-American, possibly communist for being "against" the superbomb. But this was unfair. Oppenheimer was a pro-US jihadi in his own right but people did not understand this back then. They (scientists) knew about boosted fission and knew that a superbomb would require Tritium. Oppenheimer wanted to quickly build a large arsenal with boosted fission bombs and argued that the "superbomb" may or may not work - and that since both Tritium and Plutonium were manufactured in reactors - each atom of Tritium made was one atom less of Plutonium for the US arsenal. And yes - they are built atom by atom.

US President Truman had asked for a report (the GAC report) and the main authors of the report were led by Oppenheimer and they argued against the superbomb - partly for the above reasons. Fermi and others also had a moral objection. They said a superbomb was a weapon of genocide and a country like the US should not secretly make a weapon of genocide without public debate. Teller was not very interested in this - he was interested in the fusion superbomb and was outside of the group that made this report.

Around this time the secret project was leaked to the media and the public demanded that the US needed a superbomb to protect freedom and democracy. President Truman felt his hand had been forced, like Nawaz Sharif's hand was forced in 1998, and he ordered that research should continue into the superbomb. The GAC report was ignored and Oppenheimer was accused of being a communist sympathizer and sidelined - which, as later events proved had been unfair to him. Teller was one of the people who testified against Oppenheimer suggesting that his loyalties may not have been totally with the US. In any case the superbomb was Teller's interest area.

In due course there appeared on the scene Shri Ulam, who theorized that fission bombs could be compressed by radiation to create a super-efficient fission bomb by radiation compression. Teller saw this idea and immediately thought that maybe Tritium could be compressed this way. That was how the "Teller-Ulam" idea was born. The first US thermonuclear bomb test Ivy Mike was not a usable bomb. It weighed 80 plus tons and had to have cooled Tritium. It gave 10.4 megatons.

In fact it was the Soviets who detonated the first deliverable thermonuclear device - the "Sloika design" and in fact they first showed that Tritium (which decays with time and need to be kept cooled) was not needed. They used Lithium 6 Deuteride which is the masala that is used in modern thermonuclear bombs in their Sloika design. But the need to show that "mine is bigger" has discarded the Soviet contribution as "not a true hydrogen bomb" by the Teller Ulam one as the "true" Hydrogen bomb. In actual fact only the sun is a true hydrogen bomb and neither Teller Ulam nor Sloika are that. They are both "fusion boosted fission" of a different variety. Ulam actually only wanted to compress fission fuel as a secondary rather than fusion fuel and this is a very good idea because fission fuel is easier to set off than Tritium it Li6D. In fact a Sloika can be used as a secondary to get a huge bang. So the permutations and combinations are diverse and plenty.

In fact back in those days the Soviets used to allow Britain to examine the debris and fallout after nuclear bomb tests to see what they could find. It was Britain that discovered the use of Lithium 6 Deuteride in the Sloika design and they later used it for their thermonuclear device. Their first test was a fizzle. The second worked. But they wanted to show mine is bigger and demonstrate megaton, and they did it in their third attempt because in those days no one understood what megaton devices would actually do to the environment.

For a short while when the world started protesting the environmental hazards of atmospheric testing and testing was moved underground - there was a move to try and reduce the fallout. reducing the fallout meant using a non fissile tamper thermonuclear weapons. This basically reduced their yield a great deal. Once testing went underground no one was interested in reducing fallout - they continued to get their big bangs using some fusion and mostly fission in "thermonuclear bombs"

Cold war debates in the US finally concluded that they could not eliminate and kill everyone in the Soviet Union even with thousands of megaton bombs and they could not guarantee that the USSR would not be able to send at least one bomb to hit the US. It was also realized that bombing the USSR into nuclear oblivion would cause fatal fallout all over the world starting with Europe and NATO allies were not happy. That is what prompted talks to limit nukes. History now records that what Oppenheimer and co had stated back then was correct and that he was treated unfairly.

In general the world is moving away from "megaton" bombs. The bombs that remain in inventories are old ones heading for date-expiry. Light and reliable multi-kiloton warheads seem to be the flavour of the day but no one really wants to have to either use them or have them used against their own people. So far they are being wielded only as a "deterrent"

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Re: Deterrence

Postby shiv » 01 Mar 2017 20:44

JohnTitor wrote:

Good video. I like it

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Re: Deterrence

Postby abhik » 01 Mar 2017 21:37

shiv wrote:...
2. The number of weapons needed to destroy Pakistan almost completely is out of reach of most nations currently - but they will actually destroy a large part of the world if not the whole world from fallout, starting from Pakistan's neighbours

Ok what 'completely destroy' means may be point of debate but are there any scientific studies on how many nukes of what type it will take to make a significantly large area like pakistan or even the entire world uninhabitable. The world didn't end when the Russians exploded a 50MT bomb, will it end if a thousand 50kT bombs go off in pakistan? Honest question, because I hear such statements mostly in what seem like propagandu.

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Re: Deterrence

Postby JohnTitor » 01 Mar 2017 21:40

shiv wrote:Good video. I like it

The video below is a very good video on the subject - from methodology to effects, 2 part lecture.

But going back to my original question, are we convinced that India has built up enough knowledge to perform simulations for newer/more efficient future devices? I've read through the several pages since I originally asked the question, but very little was said on simulations.

I cannot find any information regarding the Indian industry - ICF or other methods to simulate tests. Is there evidence to suggest that this exists or are we still at "we don't have enough raw data"? I feel that hot testing is not going to be possible (if at all, not for the next few decades) for economic & political reasons. Geopolitically we were late to the game and I can only hope that in the limited tests we did, we gathered enough to perform realistic simulations.


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Re: Deterrence

Postby shiv » 01 Mar 2017 21:45

JohnTitor wrote:But going back to my original question, are we convinced that India has built up enough knowledge to perform simulations for newer/more efficient future devices? I've read through the several pages since I originally asked the question, but very little was said on simulations.

No point answering this question. Almost no one on this forum understands physics, no one knows what our nuclear physicists, chemists and engineers are doing and have been doing to over 50 years, and no one believes what is written. People can believe whatever they want.

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Re: Deterrence

Postby shiv » 01 Mar 2017 21:52

abhik wrote:
shiv wrote:...
2. The number of weapons needed to destroy Pakistan almost completely is out of reach of most nations currently - but they will actually destroy a large part of the world if not the whole world from fallout, starting from Pakistan's neighbours

Ok what 'completely destroy' means may be point of debate but are there any scientific studies on how many nukes of what type it will take to make a significantly large area like pakistan or even the entire world uninhabitable. The world didn't end when the Russians exploded a 50MT bomb, will it end if a thousand 50kT bombs go off in pakistan? Honest question, because I hear such statements mostly in what seem like propagandu.

There are hundreds of studies and papers. No one will believe anything other than what the media and Hollywood tell them though

The myths that I see going around on this forum are like "Nuclear bomb will cause 100% death if it is a megaton bomb". The video posted by JohnTitor should answer your question. It is only 6 minutes. Do watch
viewtopic.php?p=2122338#p2122338

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Re: Deterrence

Postby sudeepj » 01 Mar 2017 22:05

disha wrote:SudeepJ., it is not the inertia of the tamper+neutron reflector+Pu in the sphere., it is the number of Pu atoms fissioned in the first population.

Since one starts with a smaller population of Pu fissions., the eventual population of fissioned atoms will be exponentially smaller compared to a perfect condition.


Which is why I said 'other things being equal', those other things being boosting, and the initiator. Boosting itself works by introducing a lot of fast neutrons early in the fission reaction, when just a small fraction of the yield has been generated by the device. This is why you can use reactor grade Pu in boosted weapons, because even if its a fizzle, you will likely (weapons yields are statistical, not exact) generate high enough temperatures to start fusion in the tritium and generate a large number of fast neutrons. All said and done, its the last few generations of the fission that will generate most of the energy from the weapon and the only thing that is holding the assembly together for those last few generations is the inward momentum of the pit/reflector/tamper assembly.

So, two orthogonal ways to increase yield: Add a LOT of neutrons early in the reaction (much more than fission itself releases) or Keep the assembly together as long as possible. Both of these are used in modern weapons. The first via boosting and the second by radiation implosion.

About the size of the CE lenses.

Just looking at it from a basic physics point of view, there is a theoretical maximum efficiency of a boosted fission weapon imploded with chemical exp. This appears to be around 40% (Achieved in the Mark 13 weapon, a 92 point implosion assembly!) A Kg of Pu yields about 20KT if completely fissioned. It follows that 100KT needs about 5 Kgs to undergo complete fission. Using 40% max efficiency, you will need about 12.5 Kgs of Pu in the pit. Now, this is a very dangerous (for the user) weapon because its about 2 critical masses even before compression! Even accidental detonations can cause KT level yields! Further, to keep it below criticality, you will need the pit to be a much larger sphere/hollow shell, which will increase the size of the exp lenses. This weapon will also be more likely to blow up if there is a flux of neutrons from a nearby explosion. So it will also need more shielding, which will contribute to the weight and the size of the CE lenses.

Next, consider the amount of work done in compressing the pit. Intuitively, compressing a 6Kg pit to the needed density will need less work than compressing a pit thats twice the size and being compressed to the same density.. (Intuitively, twice the energy..) Therefore, the amount of the energy released by the exp. needs to be that much more. This will be the other factor that increases the size of the weapon.
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Re: Deterrence

Postby shiv » 01 Mar 2017 22:14

JohnTitor wrote:
shiv wrote:Good video. I like it

The video below is a very good video on the subject - from methodology to effects, 2 part lecture.

If anyone understands even a little physics/chemistry - the lecture posted by AmberG is a fantastic one. One Hour and 13 minutes. All bombs are based on physics/chemistry. No physics no bomb. No understand basic physics/chem, no understand even basics of bomb. Unless someone really wants to learn - he/she can fuggedaboutit

https://www.youtube.com/watch?v=5BHdsjo-NR4

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Re: Deterrence

Postby JohnTitor » 01 Mar 2017 22:29

shiv wrote:If anyone understands even a little physics/chemistry - the lecture posted by AmberG is a fantastic one. One Hour and 13 minutes. All bombs are based on physics/chemistry. No physics no bomb. No understand basic physics/chem, no understand even basics of bomb. Unless someone really wants to learn - he/she can fuggedaboutit

https://www.youtube.com/watch?v=5BHdsjo-NR4

Thanks shiv - I've seen this a while ago. I will watch it again to refresh my memory. Physics & mathematics are my strong points.. so I generally don't struggle with the mechanics of these things. The last few pages (since i kicked up the dust) on here are very interesting.

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Re: Deterrence

Postby sudeepj » 01 Mar 2017 22:41

shiv wrote:
sudeepj wrote:
3. A 100-300KT radiation imploded weapon may have a small boosted primary of 5KT (which would yield a sub KT amount of energy without boosting) and a secondary that uses another few pounds of Pu. The dimensions and the weight of the device are determined by the size of the primary. A 20 KT or so fission or boosted fission device would be much larger with consequent effects on your missile capability.


Megaton weapons were created for maximum damage and were maximally dirty because most of the yield came from fission of tamper. Modern weapons of the 100-300 kt range have apparently (according to the same sources you and I are finding on Google) have removed the differentiation between so called "thermonuclear" and "boosted fission" because those yields are perfectly feasible in boosted fission and Uranium availability (except for India?) is not a problem any more. I am sure you can Google the refs that say this


Really? If would like to see some references. The essential difference in thermo. vs boosted fission is the velocity imparted to the fissile/fissionable material. In boosted fission using CE lenses, the theoretical max is 8km/sec while in radiation implosion, its 2-300km/sec. This velocity means that the assembly stays intact longer and allows for efficient fission and also use of U238 to get energy.

shiv wrote:
sudeepj wrote:5. Using 100KT-300KT (or MT) designs allows you to kill the entire population of a city (a genocide!) using just one missile with multiple warheads. You can not do this using fission or boosted fission only weapons, you will need perhaps an order of magnitude more missiles and Pu.

This appears to be your conclusion. Nowhere does it say anything of the sort. Lots of references say that boosted fission becomes problematic (warhead too big) for yields above 300-400 kt. TN is better for higher yields. Please check and post soucres for your conclusions. There is a lot of new info now in the same sources that I read thoroughly 6-7 years ago and like everyone else on this thread I have also been busy Googling and confirming things before saying anything


It IS my conclusion, did I claim anywhere that its yours or that of many many other people? :) For problems in large boosted devices (my understanding), read my last reply to Disha, about max theoretical efficiencies etc. Such a weapon is certainly possible but will be unsafe for the user and bulky.

shiv wrote:
sudeepj wrote:6. A mistake is being made in running mental scenarios that correspond to KT strikes in peacetime. Wartime efforts will obviously be different and a populace mobilized for wartime will have very different reactions compared to peacetime. An example of thousands of burn victims is given and a comparison is made with the medical facilities available. But the counter point is, that in the absence of such facilities, serious burn victims will simply die of infection/shock etc. in a week or so making the task of providing care moot. In the meantime, spare capacity will be mobilized from neighboring areas.

This is where I believe you have either not read or are unaware of disaster management. Or even what a disaster entails. When you have 100,000 rotting bodies in one area and 200,000 or more refugees and relatives - most of them wounded pouring out into surrounding areas and dying on the streets there the "spare capacity" of the neighbouring areas to function normally will be disrupted. Dogs, vultures and flies will pour in from surrounding areas to do their bit. Even if it is decided that "This is wartime, we will let the nuked area remain as it is" - the theory is easier than practice. ....


So how did the Japanese cities recover?
http://atomicbombmuseum.org/4_ruins.shtml
Hiroshima’s population, down to roughly 83,000 soon after the bombing, swelled to 169,000 by February of 1946.

http://time.com/3974610/hiroshima-peace-festival-1947/
In the years since the U.S. had dropped the bomb, the city’s population had recovered—not fully, but still rapidly. Of the 60,000 houses that had been destroyed, 23,000 had been rebuilt.
sudeepj wrote:8. A city can recover in the months and years ahead after a KT strike that kills or incapacitates 15% or so of its population. On the other hand, a MT strike (or three 100KT warheads) will kill a much larger fraction of that city and make its recovery impossible.


This recovery would not have happened if spare capacity from the country side had not been mobilized and if a larger fraction of the city had been killed. A radiation imploded weapon allows that.

shiv wrote:This is simply an assumption. One 15-20 kt bomb killed about 100,000 and wounded 200,000 in Hiroshima. A city that has just two bombs dropped on it will lose too many people to function in the short to medium term. But a large country can survive if one city goes. if 50 cities get hit by 2 x 20 kiloton bombs each - that country will not be in a position to continue normal function. I deliberately use the 20 kt example because that is bad enough. If you have higher yields it is OK but one needs to nuke at least 25 to 50 cities. The yield matters less than the fact of disrupting the cities.


Yes, I completely agree that in the short to medium term, the countries economy and necessary functions will grind to a halt. Many more people will die of disease, famine, exposure etc. But as long as a significant fraction of the elite (politicians, cultural elite, educators, law and order elite, bureaucracy) survive, the nation will recover in a few years. Particularly so if it defeats the enemies who launched the nukes at the nation. Note that killing a fraction of the population in 20 cities will not mean the end of the war. The soldiers at the border will continue to fight. Presumably, the command authority will have prepared for an eventuality like this and would have likely survived too. They will also continue to fight.

A thermonuclear weapon (or a large yield weapon) on the other hand, will allow you to kill many more of these elite and thus put the very survival of the nation at stake. There may be nobody left to repopulate, or the people left may not have sufficient intellectual capital to manage their affairs/conflicts/resources properly. Different regions may want independence, or new political structures or collapse to a more primitive form of political organization.

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Re: Deterrence

Postby ShauryaT » 02 Mar 2017 00:48

shiv wrote:
Shaurya you are now firmly moving the goal post from "Megatonne warheads" of Karnad to your own beliefs. That is OK as far as I am concerned

PSI on target is about height above target and accuracy. That PSI could even come from a 50 kiloton weapon placed accurately and even 10 megatons taking out 120 sq km will not be much on 1600 sq km Shanghai. Rhetoric is easy. Specifics need fleshing out. What are you talking about when you say "needed level of destruction" . These are empty words that need to be qualified. What is needed level of destruction?

But I would prefer it if you could discuss what you mean by damage to a city and what you mean by megatons to get adequate PSI . We can talk but I will not take fudging
Shiv ji: I will let you make your own determination on the "needed" level of destruction. With WMD the logic is more the better. The question is not what is minimally sufficient to be deemed by the enemy as unacceptable damage. Please use this tool to see the difference between 20KT, 100KT, 300KT and 3 MT and its effects for a given target. http://nuclearsecrecy.com/nukemap/

I "played" with the tool and here is a quick summary over a major metropolitan area. A 20 KT blast got me about 1 million dead or injured. A 3 MT on the same area got me 7 million dead or injured. An MIRV equipped 10 warheads of 300 KT each got me 14 million dead or injured as the blast and radiation area was larger and slightly dispersed. I believe the realistic cases will be far less dead or injured due to war preparations and quality and type of building materials used and other war time preparations. At some point of time there is an "optimal" configuration taking into account costs, risks, CEP, yields and the desire to inflict as large a destruction as possible and then come to an optimal number. For me that number remains between 300-500 KT for an MIRV warhead. Anything less than 100 KT on each war head seems sub optimal.

The argument is not for MT Warheads alone, the argument is for MT levels of destruction, done through a single war head or multiple is only a point of efficiency. 20 KT is not the optimal for the above desired mass destruction effect is the conclusion.

As for the small number of use cases where reinforced bunkers and silos need to be destroyed there is enough data out there to come a conclusion on the needed tonnage and accuracy needed to destroy these underground bunkers of varying depths. Something like NORAD probably needs a different strategy. For ref, please see this. https://www.nap.edu/read/11282/chapter/6#43

Do not believe Karnad is saying anything different but in India's context, the argument pre-MIRV days in 2002 was 20 KT against 3 MT.
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Re: Deterrence

Postby ShauryaT » 02 Mar 2017 02:07

The bête noire of many here opines.

The Lure and Pitfalls of MIRVs
Under these circumstances, it is inconceivable that Pakistan will ignore India’s pursuit of MIRVs and BMD. If India ight-tests MIRVs or deploys limited BMD, the only question is whether Pakistan will choose the tortoise or hare option. Pakistan’s dilemma is to contest India’s strategic modernization programs and yet avoid engaging in a debilitating arms race. But given the choice of negating India’s options or avoiding an arms race, Pakistan will choose the former. In our assessment, Pakistan will continue to factor in the evolving nature of technological asymmetries with India, and is likely to respond to the extent that it can in terms of available resources. We conclude that, based on past experience, and keeping in view the emerging imbalance in resources and access to technology, Pakistan’s most likely choice when faced with the prospect of Indian MIRVs and limited BMD will be the tortoise option.

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Re: Deterrence

Postby shiv » 02 Mar 2017 04:45

sudeepj wrote:Really? If would like to see some references. The essential difference in thermo. vs boosted fission is the velocity imparted to the fissile/fissionable material. In boosted fission using CE lenses, the theoretical max is 8km/sec while in radiation implosion, its 2-300km/sec. This velocity means that the assembly stays intact longer and allows for efficient fission and also use of U238 to get energy.


Posted earlier: http://nuclearweaponarchive.org/Nwfaq/Nfaq4-5.html
Now, once one considers using substantial amounts of HEU in the secondary, the question of why the fusion fuel is needed at all arises. The answer: it probably is not essential. The idea of imploding fissile material is what set Stanislaw Ulam on the path to that led eventually to thermonuclear weapons. But with the availability of large amounts of HEU, and the trend toward smaller weapon yields (compared to the multimegaton behemoths of the fifties), the Ulam's idea of using radiation implosion to create a light weight high-efficiency pure fission weapon returns as a viable possibility. It is an interesting question whether all modern strategic nuclear weapons *are* in fact thermonuclear devices!


http://isites.harvard.edu/fs/docs/icb.t ... design.pdf
The distinction between these two types of weapon is blurred by the fact that they
are combined in nearly all complex modern weapons: a smaller fission bomb is first used to reach the necessary
conditions of high temperature and pressure which are required for fusion. Fusion elements may also be present in
the core of fission devices as well as they generate additional neutrons which increases the efficiency (known as
"boosting") of the fission reaction. Additionally, most fusion weapons derive a substantial portion of their energy
(often around half of the total yield) from a final stage of fissioning which is enabled by the fusion reactions. Since
the distinguishing feature of both fission and fusion weapons is that they release energy from transformations of the
atomic nucleus, the best general term for all types of these explosive devices is nuclear weapon

.

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Re: Deterrence

Postby shiv » 02 Mar 2017 04:49

sudeepj wrote:
5. Using 100KT-300KT (or MT) designs allows you to kill the entire population of a city (a genocide!) using just one missile with multiple warheads. You can not do this using fission or boosted fission only weapons, you will need perhaps an order of magnitude more missiles and Pu.


It IS my conclusion, did I claim anywhere that its yours or that of many many other people? :)


The reason I stated that this was your conclusion and not that of anyone else is because it is wrong to claim that "Using 100KT-300KT (or MT) designs allows you to kill the entire population of a city ". No such law can be assumed to exist

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Re: Deterrence

Postby shiv » 02 Mar 2017 05:11

sudeep_j wrote:A thermonuclear weapon (or a large yield weapon) on the other hand, will allow you to kill many more of these elite and thus put the very survival of the nation at stake. There may be nobody left to repopulate, or the people left may not have sufficient intellectual capital to manage their affairs/conflicts/resources properly. Different regions may want independence, or new political structures or collapse to a more primitive form of political organization.

You are saying that bigger bombs will kill more elite and that it is the elite that drive a civilization. That is at least two assumptions. The elite are more likely to hide in shelters and have places to migrate to if they survive. But it is the people who do the daily grunt jobs who will die in the largest numbers and the assumption that the elite alone will carry on a civilization without the others in a post nuclear war scenario is simply speculation.

Even large yield bombs do not kill 100% of people. They just kill more. I believe that the killing power of high yield nuclear bombs is being overestimated and the danger posed by smaller yield weapons is being under estimated by what I see as a blind reliance on "number of dead" as the benchmark. It is not the number of dead but the number of live people who matter and no bomb will kill 100% and all the bombs in the world cannot cover the whole world with blast damage. I am actually amused at the respect being shown to high yield and shocked at the assumption that two smaller yield weapons on a city will somehow lead to everything being OK very soon even after 25 or 50 cities are given that treatment. I can see zero analysis as to why this is being said except for "numbers of dead" as if a lot of dead means everything will simply end there.

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Re: Deterrence

Postby shiv » 02 Mar 2017 05:26

ShauryaT wrote:With WMD the logic is more the better. The question is not what is minimally sufficient to be deemed by the enemy as unacceptable damage. Please use this tool to see the difference between 20KT, 100KT, 300KT and 3 MT and its effects for a given target. http://nuclearsecrecy.com/nukemap/

I "played" with the tool and here is a quick summary over a major metropolitan area. A 20 KT blast got me about 1 million dead or injured. A 3 MT on the same area got me 7 million dead or injured. An MIRV equipped 10 warheads of 300 KT each got me 14 million dead or injured as the blast and radiation area was larger and slightly dispersed. I believe the realistic cases will be far less dead or injured due to war preparations and quality and type of building materials used and other war time preparations. At some point of time there is an "optimal" configuration taking into account costs, risks, CEP, yields and the desire to inflict as large a destruction as possible and then come to an optimal number. For me that number remains between 300-500 KT for an MIRV warhead. Anything less than 100 KT on each war head seems sub optimal.


Shaurya words like "necessary amount" and "optimal" look good in scholarly articles. Computer games are computer games and without more detailed simulation they get tiresome after a few iterations

Can anyone state what will happen to a city with a population of 5 million people gets nuked by two weapons of unknown yield and suddenly the people left alive in the city discover that a huge swathe of the city has been flattened. No one will know the yield. No on will know how much damage was done. Only the people far away from the blast will find wounded and panicked people pouring into their quarter of the city.

Are you saying that people in this situation are going to judge whether the city has been hit by 20 kt, 200 kt or 1 megaton?

Do you personally believe that a city of 5 million will simply carry on somehow instinctively understanding that only 5% of the city area is destroyed and only 2% of 5 million dead and 5% injured by a small kiloton blast. Or will they panic more because they instinctively know that 10% are dead and 20% injured? How will they know that they must carry on because it was only 20 kiloton but suffer only when it is 1 megaton

I am asking - if this happens to 50 cities in a country - how will the leadership, or those who are left know that they have been hit by 50 x kiloton devices and not 50 x megaton devices and that they can celebrate the lives spared? Those who are dead will not feel the difference, neither will those who are wounded. Only those left alive and uninjured have to cope. How will they know that all is well because the damage is only kiloton bombs and not megaton bombs?

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Re: Deterrence

Postby sudeepj » 02 Mar 2017 05:35

shiv wrote:
sudeepj wrote:Really? If would like to see some references. The essential difference in thermo. vs boosted fission is the velocity imparted to the fissile/fissionable material. In boosted fission using CE lenses, the theoretical max is 8km/sec while in radiation implosion, its 2-300km/sec. This velocity means that the assembly stays intact longer and allows for efficient fission and also use of U238 to get energy.


Posted earlier: http://nuclearweaponarchive.org/Nwfaq/Nfaq4-5.html
Now, once one considers using substantial amounts of HEU in the secondary, the question of why the fusion fuel is needed at all arises. The answer: it probably is not essential. The idea of imploding fissile material is what set Stanislaw Ulam on the path to that led eventually to thermonuclear weapons. But with the availability of large amounts of HEU, and the trend toward smaller weapon yields (compared to the multimegaton behemoths of the fifties), the Ulam's idea of using radiation implosion to create a light weight high-efficiency pure fission weapon returns as a viable possibility. It is an interesting question whether all modern strategic nuclear weapons *are* in fact thermonuclear devices!


Easily answered.
1. Its HEU, not weapons grade, so the weapon is safer for the user. No chances of accidental criticality.
2. If the same amount of HEU were to be further enriched to weapons grade and compressed using CE, it would yield a rather unwieldy weapon.

I believe you have misunderstood the authors point. He is putting forward the irony, that the point of radiation implosion is to use fissile material efficiently, but adding HEU to the secondary is using more of the fissile material that you wanted to save! But as pointed out above, radiation implosion allows you to compress the secondary at a much higher pressure and therefore get more bang than any CE lens system ever can. (Theoretical max of 8km/sec vs 2-300km/sec implosion shockwave speed).

shiv wrote:http://isites.harvard.edu/fs/docs/icb.topic86897.files/Oct_27/nuclear_weapon_design.pdf
The distinction between these two types of weapon is blurred by the fact that they
are combined in nearly all complex modern weapons: a smaller fission bomb is first used to reach the necessary
conditions of high temperature and pressure which are required for fusion. Fusion elements may also be present in
the core of fission devices as well as they generate additional neutrons which increases the efficiency (known as
"boosting") of the fission reaction. Additionally, most fusion weapons derive a substantial portion of their energy
(often around half of the total yield) from a final stage of fissioning which is enabled by the fusion reactions. Since
the distinguishing feature of both fission and fusion weapons is that they release energy from transformations of the
atomic nucleus, the best general term for all types of these explosive devices is nuclear weapon

.


Technically correct, the best kind of correct. Its a tautology, adding absolutely nothing to the discussion.

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Re: Deterrence

Postby shiv » 02 Mar 2017 05:43

Wiki has moved on..
https://en.wikipedia.org/wiki/Thermonuclear_weapon
for destruction of cities and non-hardened targets, breaking the mass of a single missile payload down into smaller MIRV bombs, in order to spread the energy of the explosions into a "pancake" area, is far more efficient in terms of area-destruction per unit of bomb energy. This also applies to single bombs deliverable by cruise missile or other system, such as a bomber, resulting in most operational warheads in the U.S. program having yields of less than 500 kilotons.

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Re: Deterrence

Postby shiv » 02 Mar 2017 05:55

sudeepj wrote:I believe you have misunderstood the authors point. He is putting forward the irony, that the point of radiation implosion is to use fissile material efficiently, but adding HEU to the secondary is using more of the fissile material that you wanted to save! But as pointed out above, radiation implosion allows you to compress the secondary at a much higher pressure and therefore get more bang than any CE lens system ever can. (Theoretical max of 8km/sec vs 2-300km/sec implosion shockwave speed).


In fact what the author is saying is whether one uses "boosted fission" , "radiation implosion of secondary" (or in fact a Sloika design as a secondary) it is always fission boosted by fusion neutrons to get a more efficient and bigger bang. In fact Ulam originally envisaged radiation compression for fission. It can still be used for that in a design that could get 100 kilotons plus without being called a "Thermonuclear weapon" by the hair splitters

So the claims that have been made that "Thermonuclear is better than fission" is a type of fudging that carries no meaning in weapons yielding less than 500 kt. Equally meaningless is the claim that "bigger yields are because of magical fusion that is going on in thermonuclear weapons". Nothing of the sort. In every case most of the yield is from fission of more fission fuel from fast neutrons generated by the compression of fusion fuel.

Technically a well designed primary/standalone bomb can be of 10 or 20 kilotons of boosted fission with just 1 kg of Pu. A city that gets treated with 4 of these will not know the difference between that and a single 200 kiloton hit

shiv
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Re: Deterrence

Postby shiv » 02 Mar 2017 06:01

sudeepj wrote:1. Its HEU, not weapons grade,

What is the exact meaning of this? Are you suggesting that the two are different?

The idea that 55 kg (one critical mass) of bomb grade Uranium is somehow unstable or liable to explode per se is a myth that should not be propagated.

In fact this is a point specifically made in the video lecture posted above - https://www.youtube.com/watch?v=5BHdsjo-NR4

55 kg U 235 is a critical mass but for it to do bad things it has to occupy the smallest possible volume or be compressed. If it is fashioned into a long rod or even a tube that serves as a tamper its geometry can ensure the escape of neutrons in sufficient numbers to prevent detonation or even a meltdown
Last edited by shiv on 02 Mar 2017 06:22, edited 1 time in total.


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