Most readers would be able to recollect the infamous ISRP spy case. In 1994, S. Nambi Narayanan and D. Sasikumaran, both senior scientists at ISRO, were charged with espionage. Nambi Narayanan was in-charge of the cryogenics division and was instrumental in developing the Vikas cryogenic engine that would later be used for the first PSLV that India launched.It was alleged that they had sold India’s indigenous space technology to Pakistan through two Maldivian women spies.
The charges were subsequently dismissed, Narayanan was granted a record compensation of Rs. 50 lakh and the Supreme Court ordered a CBI probe into the role of Kerala police officers in framing him. In the excitement of such atrocious framing of an innocent man and his relentless legal battle to restore his honour, however, nobody paid attention to a fundamental problem with the charges.
How the Myth of Espionage endures despite Defying Logic
Please note that in 1994, leaving aside the mainframe computers used in scientific establishments that used huge 10½ inch diameter magnetic tape drives, we were still in the age of personal computers based on the Intel 386 microprocessor and 3½ inch floppy diskettes with a memory of just 1.44 MB. This means that for espionage,only the floppy disketteswere small enough to be used. However, in their small memory, nothing useful could be contained. Young persons of today who are used to iPhone13 of 128 GB cannot even imagine what it was to work with a floppy that had 89000 times less memory!
When it was not possible to transfer any useful data in floppy, no one asked how he could conceal voluminous printouts of details of such complex technology and flight test data etc. and give them to the spies without arousing suspicion?
Nuclear Weapons do not have any Secret or Magic Formula
A similar myth persists with regard to nuclear weapons also. Whenever there is a talk of nuclear proliferation, people start imagining nuclear secrets being transferred to spies. In this article, I will show for the lay person that nuclear weapons do not have any secret or magic formula, which you just have to tell someone and he will be able to make them in his basement or in the neighbourhood workshop. There is no such secret, which can be given in a pen drive to a spy! The details would be extremely voluminous, which one person cannot handle. It would require a spy ring and the cover of industrial exchange as done by the Israelis to transfer them.
The Science of Atom Bomb demystified in simple terms
The atom bomb or nuclear bomb (nuke) is a device which derives its explosive power from a phenomenon known as nuclear fission. Now what is fission? You know that atoms consist of nuclei (plural of nucleus) at their core and electrons outside. Now what makes up the nuclei? There are sub-atomic particles called protons and neutrons which make up the nuclei of atoms.
Now what we do is to take some heavy elements like Uranium-235 (i.e., uranium atom of atomic mass 235) or Plutonium-239 (i.e., plutonium atom of atomic mass 239) and bombard them with neutrons. These heavy nuclei are not very stable and they break into two fragments of roughly equal size—this is called nuclear fission. Besides them a couple of neutrons are also released.
The whole process entails release of a large amount of energy. Why? It so happens that the combined mass of the two nuclei formed and the neutrons is slightly less than the mass of the uranium or plutonium nucleus. So where does the mass go? It is actually converted into energy by the famous mass-energy equivalence relationship of Einstein, E = mc2.
The material that can undergo fission is called fissile material. Now if somehow the neutrons could hit other nuclei, they would break them too. The neutrons produced by their fission would break still more nuclei and so on. Thus a chain reaction takes place which grows exponentially and enormous amounts of energy are released in an extremely short time—that is, you get a nuclear explosion.
If you have but a small quantity of the fissile material, chances are that most of the neutrons would escape without doing anything useful—after all they are extremely small particles. If you have a sizeable quantity then chances are that they would collide with some nucleus before they are able to escape. This critical quantity of a fissile material is known as its critical mass. Below that the material is said to be a sub-critical mass. In order to make a bomb which you could explode at will, an assembly of fissile material must be brought from a sub-critical to a supercritical state extremely suddenly.
The Complexities of Making a Nuclear Bomb
Sounds fairly simple? In practice it turns out to be extremely complex. If you wish to make a bomb, you must ensure that the sub-critical pieces do not fly apart as a result of the energy produced in the first instance and thus end the progression of the chain reaction prematurely—you have to keep the supercritical mass together for about a micro-second and it is not easy because the tremendous energy released tends to throw everything apart with tremendous force. Also you must ensure that before you want to explode, stray neutrons should not be creating any mischief.
The majority of the technical difficulties of designing and manufacturing a fission weapon are based on the need to both reduce the time of assembly of a supercritical mass to a minimum and reduce the number of stray (pre-detonation) neutrons to a minimum. And, mind you, these are enormous engineering challenges.
There are basically two techniques for assembling a supercritical mass. Broadly speaking, in the ‘gun-assembly’ type, we bring two sub-critical masses together forcefully. In the other,we very quickly compress a sub-critical mass into a supercritical one—compressing the metal to nearly 2.5 times of its density. Compressing from all sides is called ‘implosion’. The first design is used with uranium and the second with plutonium. Now, uranium bombs cannot be made more powerful beyond a practical limit. After that you have to go for plutonium bombs.
For both, the first step is enrichment or increasing the percentage of the fissile isotope. However, even you somehow steal all the enriched fissile material you need; the device would not work because plutonium squirts out. What happens is that under such enormous pressures, even a metal starts flowing like a liquid and liquid has a tendency of squirting out. It is like squeezing a bunch of grapes in your palm—some juice will certainly leak out.
For achieving a sudden but uniform compression such that no plutonium is allowed to squirt out, we need something called ‘explosive lenses’. Making explosive lenses is a challenge in both the chemistry of explosives and high precision mechanical engineering.
But the problems do not end there. For making the design work, you must understand the physics of the fissile material under implosion and have the capability of doing the intricate calculations and predict how a metal being compressed that way would behave. As we said,since the metal at that pressure would be behaving like a liquid, you will have to calculate things using specialized hydrodynamic programs.
One technical problem still remains. Even if the appropriate explosive lenses could be produced, they would have to be set off simultaneously to create a symmetrical implosion. Imagine squeezing the bunch of grapes that we mentioned earlier. If some grapes are riper than others or if you are not squeezing uniformly with all the fingers, some would burst before others and start flowing out of the grip.
This means the implosion must start at the same time over all the explosive material. Now, the explosives are triggered by something called detonators. You cannot use the commercial detonators, which they use in mining etc. The detonators used here must be very precise, time-wise—they must go off within nano seconds (one billionth of a second) of each other. This requires very complex detonators called exploding-bridgewire (EBW) detonator, and slapper detonator etc.
None of the above things are available off-the-shelf even in international black market. Nor any factory makes them anywhere. The nation concerned has to make them specially for this purpose and must have the requisite physics and engineering capability to do the calculations—somebody sitting five thousand km away cannot do those calculations for you!
Then all components of nuclear weapons need to be made with a very high degree of precision. You cannot make them on lathe machines used in neighbourhood workshops. Machine tools required for making nuclear weapons include 5-axis CNC (Computer Numerically Controlled) machines in which the motions of the various axes are simultaneously and continually coordinated, thereby maintaining a predetermined (programmed) path. Special high-temperature furnaces are required for casting uranium and plutonium. You need a whole lot of extremely sophisticated machines.
Espionage Without Engineering Sophistication Will Not Do
You need to test your designs at less than full yield. The testing equipmentis extremely complicated. In a hydrodynamic test you could take inert material like U-238 and implode it exactly the way you would have imploded your fissile material and use flash X-ray or neutron cameras to see how the imploding material is behaving. In hydronuclear testing you implode fissile material alright but a supercritical mass is not maintained for a time long enough to deliver ‘full’ nuclear yield. Depending on the conditions of the test, yields may vary from milligrams to tons of TNT.
All these are very complex scientific and engineering challenges and have to be mastered by teams of specialized scientists and engineers. They have to be met by the nation that is making the bomb. You have to develop things yourself with great effort and at great expense of setting up relevant technological establishments. There is no question of someone giving any secret by espionage and an underground factory making it in no time. Espionage of such complex military secrets is just a popular myth fostered by James Bond films and the like. The myth endures because people lack critical faculties, and they refuse to apply any mind to it.
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