burns at 13,000 m.
Anything which throws a shadow will provide protection, and a British study in the 1960s showed that in the UK in peacetime in daylight some 10 per cent of the population (approximately 5 million people) was in the open at any one time, but that 75 per cent (3.75 million) of these would always be offered at least some protection by buildings. If adequate warning of an impending nuclear strike had been given, however, it would have been reasonable to expect that the numbers in the open would be substantially reduced.
Initial Nuclear Radiation
A very powerful pulse of initial nuclear radiation (INR) is released within the first minute of an explosion. INR expands in a circular pattern and is relatively short-ranged: the lethal range for a 1 MT weapon, for example, is 2,600 m. INR consists, in the main, of neutrons and gamma rays which penetrate the body and react with bone marrow, but these are substantially attenuated by dense materials such as concrete, steel or earth, so that people inside a building, in a steel vehicle (such as a battle tank or an armoured personnel carrier) or in an underground bunker receive varying degrees of protection.
People in the open are very vulnerable to INR, and the majority of radiation victims at Hiroshima and Nagasaki suffered from this initial radiation rather than from fallout. With high-yield nuclear weapons, however, the blast effect has a greater lethal range than INR, so that above a yield of about 100 kT INR ceases to be significant.
The ‘enhanced radiation warhead’ (popularly known as the ‘neutron bomb’) was designed to optimize the effects of INR, by using low-yield weapons in low airbursts over a target such as a company of tanks. The INR would have penetrated the armour and inflicted high radiation doses, while the low blast effect would have caused little serious damage to vehicles or buildings.
Residual Nuclear Radiation
Residual nuclear radiation is caused by materials which are vaporized in the initial heat and then sucked up as dust into the fireball, where they are irradiated and then fall back to earth as radioactive fallout. Larger particles return to earth within a few hours, but the remaining, increasingly small, particles may take weeks, or even months, to return to earth. The area covered lies downwind of ground zero and is generally elliptical in shape, giving rise to its colloquial name of the ‘fallout plume’.
Radiation is measured in
rads
, and accumulated doses have the following effects: fn6
• 5,000 rads and above: death in up to two days;
• 1,000 to 5,000 rads: death within fourteen days, although the lower the dose the more protracted the period;
• 600 to 1,000 rads: 90–100 per cent deaths over a period of up to six weeks;
• 200 to 600 rads: 0 to 90 per cent deaths over a period of 2 to 12 weeks;
• below 200 rads: no long-term effects, although there will be a period of several weeks’ convalescence from effects of radiation such as skin burns etc.
Table 7.1 Examples of Lethal Effects of a Nuclear Explosion 2
Ionization of the Atmosphere
Nuclear explosions cause ionization of the atmosphere, which affects radio and radar systems whose waves pass through the disturbed areas. The period of disruption may be brief (a few seconds) or lengthy (several hours), and the severity will depend upon the yield of the nuclear explosion and its height, as well as upon the characteristics of the equipment itself. Systems which depend upon reflected waves, such as radars, tropospheric scatter systems and high-frequency radios, would be particularly affected. fn7
Electromagnetic Pulse (EMP)
EMP is an extremely powerful short-duration burst of broad-band radio energy generated by a nuclear explosion. This could affect electronic equipment, such as telephone systems, radio and television equipment, radars, computers and power supplies. As far as is known, it is harmless to man and animals.
EMP travels with the speed of
Anything which throws a shadow will provide protection, and a British study in the 1960s showed that in the UK in peacetime in daylight some 10 per cent of the population (approximately 5 million people) was in the open at any one time, but that 75 per cent (3.75 million) of these would always be offered at least some protection by buildings. If adequate warning of an impending nuclear strike had been given, however, it would have been reasonable to expect that the numbers in the open would be substantially reduced.
Initial Nuclear Radiation
A very powerful pulse of initial nuclear radiation (INR) is released within the first minute of an explosion. INR expands in a circular pattern and is relatively short-ranged: the lethal range for a 1 MT weapon, for example, is 2,600 m. INR consists, in the main, of neutrons and gamma rays which penetrate the body and react with bone marrow, but these are substantially attenuated by dense materials such as concrete, steel or earth, so that people inside a building, in a steel vehicle (such as a battle tank or an armoured personnel carrier) or in an underground bunker receive varying degrees of protection.
People in the open are very vulnerable to INR, and the majority of radiation victims at Hiroshima and Nagasaki suffered from this initial radiation rather than from fallout. With high-yield nuclear weapons, however, the blast effect has a greater lethal range than INR, so that above a yield of about 100 kT INR ceases to be significant.
The ‘enhanced radiation warhead’ (popularly known as the ‘neutron bomb’) was designed to optimize the effects of INR, by using low-yield weapons in low airbursts over a target such as a company of tanks. The INR would have penetrated the armour and inflicted high radiation doses, while the low blast effect would have caused little serious damage to vehicles or buildings.
Residual Nuclear Radiation
Residual nuclear radiation is caused by materials which are vaporized in the initial heat and then sucked up as dust into the fireball, where they are irradiated and then fall back to earth as radioactive fallout. Larger particles return to earth within a few hours, but the remaining, increasingly small, particles may take weeks, or even months, to return to earth. The area covered lies downwind of ground zero and is generally elliptical in shape, giving rise to its colloquial name of the ‘fallout plume’.
Radiation is measured in
rads
, and accumulated doses have the following effects: fn6
• 5,000 rads and above: death in up to two days;
• 1,000 to 5,000 rads: death within fourteen days, although the lower the dose the more protracted the period;
• 600 to 1,000 rads: 90–100 per cent deaths over a period of up to six weeks;
• 200 to 600 rads: 0 to 90 per cent deaths over a period of 2 to 12 weeks;
• below 200 rads: no long-term effects, although there will be a period of several weeks’ convalescence from effects of radiation such as skin burns etc.
Table 7.1 Examples of Lethal Effects of a Nuclear Explosion 2
Ionization of the Atmosphere
Nuclear explosions cause ionization of the atmosphere, which affects radio and radar systems whose waves pass through the disturbed areas. The period of disruption may be brief (a few seconds) or lengthy (several hours), and the severity will depend upon the yield of the nuclear explosion and its height, as well as upon the characteristics of the equipment itself. Systems which depend upon reflected waves, such as radars, tropospheric scatter systems and high-frequency radios, would be particularly affected. fn7
Electromagnetic Pulse (EMP)
EMP is an extremely powerful short-duration burst of broad-band radio energy generated by a nuclear explosion. This could affect electronic equipment, such as telephone systems, radio and television equipment, radars, computers and power supplies. As far as is known, it is harmless to man and animals.
EMP travels with the speed of
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