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Nuclear bomb attack scenario
Bombing Bombay?

Dr MV Ramana, currently at the Center for International Studies at the Massachusetts Institute of Technology [MIT], Cambridge, USA, has estimated the effects of a nuclear bomb attack on a South Asian city in a paper titled 'Bombing Bombay? Effects of nuclear weapons and a case study of a hypothetical explosion', dated 6 June 98, to be published by the IPPNW [International Physicians for the Prevention of Nuclear War]. This note is an attempt to summarize the major points, both general and Mumbai-specific, made in that paper.

First, the general points that address the effects of any nuclear explosion.

1. There is a basic difference between nuclear explosions and those with conventional chemical explosives. The energy output of an explosion is a consequence of the release of the binding energies in the explosive constituents. In chemical explosives, these binding energies are the interatomic energies, while in nuclear energies, they are the subatomic energies. Nuclear binding energies are so much higher than chemical binding energies that the resultant huge increase in the output of energy and destruction in a nuclear blast makes it almost impossible to conceive of a 'small' nuclear blast of limited enough effective radius to be a 'discriminating' weapon.

2. The major form of energy release in a nuclear explosion is high-energy x-rays, which heat the air to create a fireball in which temperatures exceed 300,000 degrees Celsius, no matter what size of nuclear bomb is used. In comparison, chemical explosions are unlikely to exceed 5,000 degrees Celsius. The light itself is sufficient to burn people's eyes out. The fireball then expands onto a 'blast' wave as well as into radiation output.

3. The combined original and reflected shockwaves, or the 'Mach front', from a nuclear explosion hits all obstacles, animate or inanimate, and then subjects them to pressures up to a thousand-fold beyond normal. The first effect throws objects and people about, the second effect crushes them. Even with 'very small' nuclear weapons of a kiloton or so, the pressure is enough to destroy 'kutccha' housing in a range over a kilometre in diameter.

4. Hurricane-scale winds are created by this blast wave. Again, even with a 'very small' nuclear weapon of a kiloton, winds of over 60 km/h will be created over a range of a kilometre in diameter.

5. The combined effect of the light and heat of the explosion leads to very high 'radiant' exposure for many miles around. This causes burns on people and animals, and starts fires at distances far from the site of the blast. Again, with a 'small' one-kiloton nuclear bomb, paper, leaves, grass and skin can burn in a range of over a kilometre in diameter. This radiant exposure leads to the formation of 'spontaneous' fires raging in the blast area that coalesce and create 'firestorms' that create their own winds and feed themselves.

6. The next effect to be considered is the immediate nuclear radiation from the explosion. A radiation dose of about 400 rads kills. Once again, with a 'small' one-kiloton nuclear bomb, this dosage can be reached over a range more than a kilometre in diameter.

7. The delayed nuclear radiation is due to the radioactive isotopic material that comes drifting from the air to the ground after the explosion. This contains isotopes that have short half- lives of either weeks to months [barium-40 or strontium-89], years [strontium-90 or cesium- 137], or centuries [plutonium-239]. A radiation dose of about 30 rads per hour, which will reach killing doses in overnight exposure, can be reached over a 25 square mile region by a 'small' one-kiloton nuclear bomb.

Next, the specific points Dr Ramana makes about a hypothetical nuclear bomb blast. These use a scenario of a Hiroshima-scale nuclear bomb explosion over Mumbai [perhaps better renamed again now as 'Bomb'ay, given its proximity to BARC].

8. If a blast is over the Fort area, most of the island from Victoria Terminus [or rather, Chhatrapati Shivaji terminus] south to Colaba will be utterly destroyed. Firestorms are calculated to start over an area twice this size.

9. Buildings in Mumbai tend to fall down by themselves in the rains, and are therefore unlikely to withstand a nuclear blast particularly well. These collapses are likely to be seen over a much wider area. The spontaneous explosions of household materials such as, say, LPG cylinders, will further worsen this process.

10. The fires, the building collapses and the pressure effect-mediated damage to water pipes and to train tracks and roads will mean that transport, communication and fire-fighting abilities will be almost completely paralyzed in as crowded a city as Mumbai. Civil defence will therefore be of minimal help. Given the population densities in Mumbai, a conservative estimate of only the immediate casualties by just these effects of the nuclear bomb [not counting the fallout effects] is about 200,000 people.

11. The radiation fallout will reach overnight lethality levels of 30 rads per hour over an area of 150 square miles, or the bulk of Greater Mumbai and adjoining areas. Even if it is assumed, unrealistically, that people will be evacuated rapidly and that they will be in fallout areas for no more than an hour, fallout deaths given the population densities of Mumbai can add another 100,000-200,000 casualties to those caused by the blast and firestorm effects, especially if fallout is brought to ground efficiently by water condensation in the atmosphere leading to 'fallout rain'. These estimates are still in the realm of 'short-term' deaths, and do not take long-term and non-fatal effects of persistent radioactive exposure into account.

12. These estimates are extremely conservative and take no account of the destruction of medical facilities, the damage to chemical industries leading to toxic spills of extremely hazardous chemicals reminiscent of the Union Carbide incident in Bhopal, or of the possibility that there would be either intended or unintentional damage to the nuclear reactor at Trombay. This would multiply casualties astronomically.

13. It is appropriate to quote the conclusion in Dr Ramana's own words. 'The immense scale of these effects, and that too resulting from just a single fission weapon with a low yield, should make it clear that the possible use of such weapons would lead to a major catastrophe. The only guarantee that such a tragedy would never occur is complete elimination of nuclear weapons, both from the region and from the world, and the means to manufacture them'.

Nagasaki, August 10, 1945 : The charred body of a boy