atomic tecnology

When the photographs and video footage of Pakistan's nuclear tests
were released, the Pakistani public was struck by awe with the

powerful glow which illumined the mountain under which the explosions

took place. Though this was partly a photographic trick, which

highlighted the infrared (or heat) energy that the explosion

generated, it was still an austere and ominous preview of what a

nuclear explosion can do. From casual conversations with citizens

around the country soon after the tests, I gained an impression that

most Pakistanis think of nuclear weapons as just another more powerful

kind of weapon. The magnitude of even a modest nuclear explosion has

not yet surfaced to cognition in most minds.

So let us try and recount what actually happens when a nuclear bomb

explodes, such as the 13-kiloton bomb which exploded over Hiroshima in

1945. Although this was a very primitive nuclear device, it managed to

kill over 45,000 people within 24 hours of the blast and several

generations continue to languish as casualties.

Unlike conventional explosives which rely on the energy generated by

chemical combustion, nuclear weapons rely on the extreme energy which

is generated when an atomic reaction takes place in which one element

is converted into another element (for example when hydrogen is

converted to helium). The difference in the energy which is generated

is immense. For example a sphere of plutonium about the size of a

cricket ball is capable of producing an explosion equivalent to 20,000

tons of TNT. There are basically three types of nuclear bombs which

have been developed. The first kind are atomic bombs which use

fission reactions, or the splitting of atomic nuclei to generate

energy. This is the kind of bomb which was dropped by the Americans on

the Japanese cities of Hiroshima and Nagasaki in 1945. The second

variety are thermonuclear devices which use an atomic trigger and a

uranium jacket to start a fusion reaction in which lighter elements

such as hydrogen are forced to undergo a fusion reaction to combine

and form a heavier element. The energy liberated from 0.5 kg (1.1 lb)

of hydrogen-isotope fuel is equivalent to that of about 29 kilotons of

TNT, or almost three times as much as from the uranium in an atomic

bomb. The environmental impact of both these bombs would, however, be

similar though the magnitude would be greater in the case of a

thermonuclear device. The third kind of nuclear weapon is the neutron

bomb which is a modified thermonuclear device that does not have a

uranium jacket and thus reduces the chance of widespread radioactive

fallout. The neutrons generated from the thermonuclear device can,

however, generate radioactivity within a small impact radius, killing

life but without causing widespread fallout destruction to buildings

and infrastructure (the neutron bomb is thus a tactical weapon).