Archive for the Enviroment Category

Effects of Nuclear Weapons, Part III

Posted in Enviroment on January 23, 2011 by Aksyn Elek

Radiation Effects on Human Body

(1) Hair

The losing of hair quickly and in clumps occurs with radiation exposure at 200 rems or higher.

(2) Brain

Since brain cells do not reproduce, they won’t be damaged directly unless the exposure is 5,000 rems or greater. Like the heart, radiation kills nerve cells and small blood vessels, and can cause seizures and immediate death.

(3) Thyroid

The certain body parts are more specifically affected by exposure to different types of radiation sources. The thyroid gland is susceptible to radioactive iodine. In sufficient amounts, radioactive iodine can destroy all or part of the thyroid. By taking potassium iodide, one can reduce the effects of exposure.

(4) Blood System

When a person is exposed to around 100 rems, the blood’s lymphocyte cell count will be reduced, leaving the victim more susceptible to infection. This is often refered to as mild radiation sickness. Early symptoms of radiation sickness mimic those of flu and may go unnoticed unless a blood count is done.According to data from Hiroshima and Nagaski, show that symptoms may persist for up to 10 years and may also have an increased long-term risk for leukemia and lymphoma.

(5) Heart

Intense exposure to radioactive material at 1,000 to 5,000 rems would do immediate damage to small blood vessels and probably cause heart failure and death directly.

(6) Gastrointestinal Tract

Radiation damage to the intestinal tract lining will cause nausea, bloody vomiting and diarrhea. This is occurs when the victim’s exposure is 200 rems or more. The radiation will begin to destroy the cells in the body that divide rapidly. These including blood, GI tract, reproductive and hair cells, and harms their DNA and RNA of surviving cells.

(7) Reproductive Tract

Picture by Mephistofff @ DeviantArt

Picture by Mephistofff @ DeviantArt

Because reproductive tract cells divide rapidly, these areas of the body can be damaged at rem levels as low as 200. Long-term, some radiation sickness victims will become sterile.

Source: www.atomicarchive.com

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Effects of Nuclear Weapons, Part II

Posted in Enviroment on January 23, 2011 by Aksyn Elek



Radiation Effects on Humans

Certain body parts are more specifically affected by exposure to different types of radiation sources. Several factors are involved in determining the potential health effects of exposure to radiation. These include:

The size of the dose (amount of energy deposited in the body)
The ability of the radiation to harm human tissue
Which organs are affected
The most important factor is the amount of the dose – the amount of energy actually deposited in your body. The more energy absorbed by cells, the greater the biological damage. Health physicists refer to the amount of energy absorbed by the body as the radiation dose. The absorbed dose, the amount of energy absorbed per gram of body tissue, is usually measured in units called rads. Another unit of radation is the rem, or roentgen equivalent in man. To convert rads to rems, the number of rads is multiplied by a number that reflects the potential for damage caused by a type of radiation. For beta, gamma and X-ray radiation, this number is generally one. For some neutrons, protons, or alpha particles, the number is twenty.

Hair

The losing of hair quickly and in clumps occurs with radiation exposure at 200 rems or higher.

Brain

Since brain cells do not reproduce, they won’t be damaged directly unless the exposure is 5,000 rems or greater. Like the heart, radiation kills nerve cells and small blood vessels, and can cause seizures and immediate death.

Thyroid

The certain body parts are more specifically affected by exposure to different types of radiation sources. The thyroid gland is susceptible to radioactive iodine. In sufficient amounts, radioactive iodine can destroy all or part of the thyroid. By taking potassium iodide can reduce the effects of exposure.

Blood System

When a person is exposed to around 100 rems, the blood’s lymphocyte cell count will be reduced, leaving the victim more susceptible to infection. This is often refered to as mild radiation sickness. Early symptoms of radiation sickness mimic those of flu and may go unnoticed unless a blood count is done.According to data from Hiroshima and Nagaski, show that symptoms may persist for up to 10 years and may also have an increased long-term risk for leukemia and lymphoma. For more information, visit Radiation Effects Research Foundation.

Heart

Intense exposure to radioactive material at 1,000 to 5,000 rems would do immediate damage to small blood vessels and probably cause heart failure and death directly.

Gastrointestinal Tract

Radiation damage to the intestinal tract lining will cause nausea, bloody vomiting and diarrhea. This is occurs when the victim’s exposure is 200 rems or more. The radiation will begin to destroy the cells in the body that divide rapidly. These including blood, GI tract, reproductive and hair cells, and harms their DNA and RNA of surviving cells.

Reproductive Tract

Because reproductive tract cells divide rapidly, these areas of the body can be damaged at rem levels as low as 200. Long-term, some radiation sickness victims will become sterile.

Dose-rem Effects
5-20 Possible late effects; possible chromosomal damage.
20-100 Temporary reduction in white blood cells.
100-200 Mild radiation sickness within a few hours: vomiting, diarrhea, fatigue; reduction in resistance to infection.
200-300 Serious radiation sickness effects as in 100-200 rem and hemorrhage; exposure is a Lethal Dose to 10-35% of the population after 30 days (LD 10-35/30).
300-400 Serious radiation sickness; also marrow and intestine destruction; LD 50-70/30.
400-1000 Acute illness, early death; LD 60-95/30.
1000-5000 Acute illness, early death in days; LD 100/10.


Long Term Effects on Humans

Long after the acute effects of radiation have subsided, radiation damage continues to produce a wide range of physical problems. These effects- including leukemia, cancer, and many others- appear two, three, even ten years later.

Blood Disorders

According to Japanese data, there was an increase in anemia among persons exposed to the bomb. In some cases, the decrease in white and red blood cells lasted for up to ten years after the bombing.

Cataracts

There was an increase in cataract rate of the survivors at Hiroshima and Nagasaki, who were partly shielded and suffered partial hair loss.

Malignant Tumors

All ionizing radiation is carcinogenic, but some tumor types are more readily generated than others. A prevalent type is leukemia. The cancer incidence among survivors of Hiroshima and Nagasaki is significantly larger than that of the general population, and a significant correlation between exposure level and degree of incidence has been reported for thyroid cancer, breast cancer, lung cancer, and cancer of the salivary gland. Often a decade or more passes before radiation-caused malignancies appear.

Keloids

Beginning in early 1946, scar tissue covering apparently healed burns began to swell and grow abnormally. Mounds of raised and twisted flesh, called keloids, were found in 50 to 60 percent of those burned by direct exposure to the heat rays within 1.2 miles of the hypocenter. Keloids are believed to be related to the effects of radiation.


Radioactive Fallout

Fallout is the radioactive particles that fall to earth as a result of a nuclear explosion. It consists of weapon debris, fission products, and, in the case of a ground burst, radiated soil. Fallout particles vary in size from thousandths of a millimeter to several millimeters. Much of this material falls directly back down close to ground zero within several minutes after the explosion, but some travels high into the atmosphere. This material will be dispersed over the earth during the following hours, days (and) months. Fallout is defined as one of two types: early fallout, within the first 24 hours after an explosion, or delayed fallout, which occurs days or years later.

Most of the radiation hazard from nuclear bursts comes from short-lived radionuclides external to the body; these are generally confined to the locality downwind of the weapon burst point. This radiation hazard comes from radioactive fission fragments with half-lives of seconds to a few months, and from soil and other materials in the vicinity of the burst made radioactive by the intense neutron flux.

Most of the particles decay rapidly. Even so, beyond the blast radius of the exploding weapons there would be areas (hot spots) the survivors could not enter because of radioactive contamination from long-lived radioactive isotopes like strontium 90 or cesium 137. For the survivors of a nuclear war, this lingering radiation hazard could represent a grave threat for as long as 1 to 5 years after the attack.

Predictions of the amount and levels of the radioactive fallout are difficult because of several factors. These include; the yield and design of the weapon, the height of the explosion, the nature of the surface beneath the point of burst, and the meteorological conditions, such as wind direction and speed.

An air burst can produce minimal fallout if the fireball does not touch the ground. On the other hand, a nuclear explosion occurring at or near the earth’s surface can result in severe contamination by the radioactive fallout.


Fallout Particles

Many fallout particles are especially hazardous biologically. Some of the principal radioactive elements are as follows:

Strontium 90 is very long-lived with a half-life of 28 years. It is chemically similar to calcium, causing it to accumulate in growing bones. This radiation can cause tumors, leukemia, and other blood abnormalities.

Iodine 131 has a half-life of 8.1 days. Ingestion of it concentrates in the thyroid gland. The radiation can destroy all or part of the thyroid. Taking potassium iodide can reduce the effects.

The amount of tritium released varies by bomb design. It has a half-life of 12.3 years and can be easily ingested, since it can replace a hydrogen in water. The beta radiation can cause lung cancer.

Cesium 137 has a half-life of 30 years. It does not present as large a biological threat as Strontium 90. It behaves similar to potassium, and will distribute fairly uniformly thoughout the body. This can contribute to gonadal irradiation and genetic damage.

When a plutonium weapon is exploded, not all of the plutonium is fissioned. Plutonium 239 has a half-life of 24,400 years. Ingestion of as little as 1 microgram of plutonium, a barely visible speck, is a serious health hazard causing the formation of bone and lung tumors.

The details of the actual fallout pattern depend on wind speed and direction and on the terrain. The fallout will contain about 60 percent of the total radioactivity. The largest particles will fall within a short distance of ground zero. Smaller particles will require many hours to return to earth and may be carried hundreds of miles. This means that a surface burst can produce serious contamination far from the point of detonation.


This map shows the total dose contours from early fallout from a surface burst of a 1-megaton fission yield.



From the 15-megaton thermonuclear device tested at Bikini Atoll on March 1, 1954 – the BRAVO shot of Operation CASTLE – the fallout caused substantial contamination over an area of more than 7,000 square miles. The contaminated region was roughly cigar-shaped and extended more than 20 miles upwind and over 350 miles downwind.


Ozone Depletion

When a nuclear weapon explodes in the air, the surrounding air is subjected to great heat, followed by relatively rapid cooling. These conditions are ideal for the production of tremendous amounts of nitric oxides. These oxides are carried into the upper atmosphere, where they reduce the concentration of protective ozone. Ozone is necessary to block harmful ultraviolet radiation from reaching the Earth’s surface.


Oxides of nitrogen form a catalytic cycle to reduce the protective ozone layer.



The nitric oxides produced by the weapons could reduce the ozone levels in the Northern Hemisphere by as much as 30 to 70 percent. Such a depletion might produce changes in the Earth’s climate, and would allow more ultraviolet radiation from the sun through the atmosphere to the surface of the Earth, where it could produce dangerous burns and a variety of potentially dangerous ecological effects.

It has been estimated that as much as 5,000 tons of nitric oxide is produced for each megaton of nuclear explosive power.


Nuclear Winter

In 1983, R.P. Turco, O.B. Toon, T.P. Ackerman, J.B. Pollack, and Carl Sagan (referred to as TTAPS) published a paper entitled “Global Atmospheric Consequences of Nuclear War” which is the foundation on which the nuclear winter theory is based on.

Theory states that nuclear explosions will set off firestorms over many cities and forests within range. Great plumes of smoke, soot, and dust would be sent aloft from these fires, lifted by their own heating to high altitudes where they could drift for weeks before dropping back or being washed out of the atmosphere onto the ground. Several hundred million tons of this smoke and soot would be shepherded by strong west-to-east winds until they would form a uniform belt of particles encircling the Northern Hemisphere.

These thick black clouds could block out all but a fraction of the sun’s light for a period as long as several weeks. The conditions of semidarkness, killing frosts, and subfreezing temperatures, combined with high doses of radiation from nuclear fallout, would interrupt plant photosynthesis and could thus destroy much of the Earth’s vegetation and animal life. The extreme cold, high radiation levels, and the widespread destruction of industrial, medical, and transportation infrastructures along with food supplies and crops would trigger a massive death toll from starvation, exposure, and disease.

It is not certain that a nuclear war would produce a nuclear winter effect. However, it remains a possibility and the TTAPS study concluded: “…the possibility of the extinction of Homo Sapiens cannot be excluded.”


Source: http://www.atomicarchive.com/Effects/effects15.shtml

Effects of Nuclear Weapons, Part I

Posted in Enviroment on January 23, 2011 by Aksyn Elek



The Energy from a Nuclear Weapon

One of the fundamental differences between a nuclear and a conventional explosion is that nuclear explosions can be many thousands (or millions) of times more powerful than the largest conventional detonations. Both types of weapons rely on the destructive force of the blast or shock wave. However, the temperatures reached in a nuclear explosion are very much higher than in a conventional explosion, and a large proportion of the energy in a nuclear explosion is emitted in the form of light and heat, generally referred to as thermal energy. This energy is capable of causing skin burns and of starting fires at considerable distances. Nuclear explosions are also accompanied by various forms of radiation, lasting a few seconds to remaining dangerous over an extended period of time.





Approximately 85 percent of the energy of a nuclear weapon produces air blast (and shock), thermal energy (heat). The remaining 15 percent of the energy is released as various type of nuclear radiation. Of this, 5 percent constitutes the initial nuclear radiation, defined as that produced within a minute or so of the explosion, are mostly gamma rays and neutrons. The final 10 percent of the total fission energy represents that of the residual (or delayed) nuclear radiation, which is emitted over a period of time. This is largely due to the radioactivity of the fission products present in the weapon residues, or debris, and fallout after the explosion.

The “yield” of a nuclear weapon is a measure of the amount of explosive energy it can produce. The yield is given in terms of the quantity of TNT that would generate the same amount of energy when it explodes. Thus, a 1 kiloton nuclear weapon is one which produces the same amount of energy in an explosion as does 1 kiloton (1,000 tons) of TNT. Similarly, a 1 megaton weapon would have the energy equivalent of 1 million tons of TNT. One megaton is equivalent to 4.18 x 1015 joules.

In evaluating the destructive power of a weapons system, it is customary to use the concept of equivalent megatons (EMT). Equivalent megatonnage is defined as the actual megatonnage raised to the two-thirds power:

EMT = Y2/3 where Y is in megatons.

This relation arises from the fact that the destructive power of a bomb does not vary linearly with the yield. The volume the weapon’s energy spreads into varies as the cube of the distance, but the destroyed area varies at the square of the distance.

Thus 1 bomb with a yield of 1 megaton would destroy 80 square miles. While 8 bombs, each with a yield of 125 kilotons, would destroy 160 square miles. This relationship is one reason for the development of delivery systems that could carry multiple warheads (MIRVs).


Basic Effects of Nuclear Weapons

Nuclear explosions produce both immediate and delayed destructive effects. Blast, thermal radiation, and prompt ionizing radiation cause significant destruction within seconds or minutes of a nuclear detonation. The delayed effects, such as radioactive fallout and other possible environmental effects, inflict damage over an extended period ranging from hours to years. Each of these effects are calculated from the point of detonation.

Ground Zero

The term “ground zero” refers to the point on the earth’s surface immediately below (or above) the point of detonation. For a burst over (or under) water, the corresponding point is generally called “surface zero”. The term “surface zero” or “surface ground zero” is also commonly used for ground surface and underground explosions. In some publications, ground (or surface) zero is called the “hypocenter” of the explosion.

Blast Effects

Most damage comes from the explosive blast. The shock wave of air radiates outward, producing sudden changes in air pressure that can crush objects, and high winds that can knock objects down. In general, large buildings are destroyed by the change in air pressure, while people and objects such as trees and utility poles are destroyed by the wind.

The magnitude of the blast effect is related to the height of the burst above ground level. For any given distance from the center of the explosion, there is an optimum burst height that will produce the greatest change in air pressure, called overpressure, and the greater the distance the greater the optimum burst height. As a result, a burst on the surface produces the greatest overpressure at very close ranges, but less overpressure than an air burst at somewhat longer ranges.

When a nuclear weapon is detonated on or near Earth’s surface, the blast digs out a large crater. Some of the material that used in be in the crater is deposited on the rim of the crater; the rest is carried up into the air and returns to Earth as radioactive fallout. An explosion that is farther above the Earth’s surface than the radius of the fireball does not dig a crater and produces negligible immediate fallout. For the most part, a nuclear blast kills people by indirect means rather than by direct pressure.

Thermal Radiation Effects

Approximately 35 percent of the energy from a nuclear explosion is an intense burst of thermal radiation, i.e., heat. The effects are similar to the effect of a two-second flash from an enormous sunlamp. Since the thermal radiation travels at roughly the speed of light, the flash of light and heat precedes the blast wave by several seconds, just as lightning is seen before thunder is heard.

The visible light will produce “flashblindness” in people who are looking in the direction of the explosion. Flashblindness can last for several minutes, after which recovery is total. If the flash is focused through the lens of the eye, a permanent retinal burn will result. At Hiroshima and Nagasaki, there were many cases of flashblindness, but only one case of retinal burn, among the survivors. On the other hand, anyone flashblinded while driving a car could easiIy cause permanent injury to himself and to others.

Skin burns result from higher intensities of light, and therefore take place closer to the point of explosion. First-degree, second-degree and third-degree burns can occur at distances of five miles away from the blast or more. Third-degree burns over 24 percent of the body, or second-degree burns over 30 percent of the body, will result in serious shock, and will probably prove fatal unless prompt, specialized medical care is available. The entire United States has facilities to treat 1,000 or 2,000 severe burn cases. A single nuclear weapon could produce more than 10,000.

The thermal radiation from a nuclear explosion can directly ignite kindling materials. In general, ignitable materials outside the house, such as leaves or newspapers, are not surrounded by enough combustible material to generate a self-sustaining fire. Fires more likely to spread are those caused by thermal radiation passing through windows to ignite beds and overstuffed furniture inside houses. Another possible source of fires, which might be more damaging in urban areas, is indirect. Blast damage to Stores, water heaters, furnaces, electrical circuits or gas lines would ignite fires where fuel is plentiful.

Direct Nuclear Radiation Effects

Direct radiation occurs at the time of the explosion. It can be very intense, but its range is limited. For large nuclear weapons, the range of intense direct radiation is less than the range of lethal blast and thermal radiation effects. However, in the case of smaller weapons, direct radiation may be the lethal effect with the greatest range. Direct radiation did substantial damage to the residents of Hiroshima and Nagasaki. Human response to ionizing radiation is subject to great scientific uncertainty and intense controversy. It seems likely that even small doses of radiation do some harm.

Fallout

Fallout radiation is received from particles that are made radioactive by the effects of the explosion, and subsequently distributed at varying distances from the site of the blast. While any nuclear explosion in the atmosphere produces some fallout, the fallout is far greater if the burst is on the surface, or at least low enough for the firebalI to touch the ground. The significant hazards come from particles scooped up from the ground and irradiated by the nuclear explosion. The radioactive particles that rise only a short distance (those in the “stem” of the familiar mushroom cloud) will fall back to earth within a matter of minutes, landing close to the center of the explosion. Such particles are unlikely to cause many deaths, because they will fall in areas where most people have already been killed. However, the radioactivity will complicate efforts at rescue or eventual reconstruction. The radioactive particles that rise higher will be carried some distance by the wind before returning to Earth, and hence the area and intensity of the fallout is strongly influenced by local weather conditions. Much of the material is simply blown downwind in a long plume. Rainfall also can have a significant influence on the ways in which radiation from smaller weapons is deposited, since rain will carry contaminated particles to the ground. The areas receiving such contaminated rainfall would become “hot spots,” with greater radiation intensity than their surroundings.


Types of Nuclear Explosions

The effects of a nuclear explosion depend in part to the height of the detonation. There five general classifications of bursts: air, high-altitude, underwater, underground, and surface bursts.

An air burst is defined as one in which the explosion occurs in the air at an altitude below 100,000 feet (30,480 meters), but at such a height that the fireball does not touch the surface of the earth. A detontation above that altitude is generally refered to as a high-altitude burst.

A nuclear explosion that occurs at or slightly above the actual surface of the land or water is known as a surface burst. If the explosion happens beneath the surface of the land or water, then it is known as underground or underwater respectively. The design of Robust Nuclear Earth Penetrator (RNEP) uses the charaterastics of an underground burst in an attempt to destroy buried targets.

One of the greatest results of the type of burst is the amount of radioactive debris and fallout, and the force of the blast wave.


The Blast Wave

A fraction of a second after a nuclear explosion, the heat from the fireball causes a high-pressure wave to develop and move outward producing the blast effect. The front of the blast wave, i.e., the shock front, travels rapidly away from the fireball, a moving wall of highly compressed air.



The effects of the blast wave on a typical wood framed house.


The air immediately behind the shock front is accelerated to high velocities and creates a powerful wind. These winds in turn create dynamic pressure against the objects facing the blast. Shock waves cause a virtually instantaneous jump in pressure at the shock front. The combination of the pressure jump (called the overpressure) and the dynamic pressure causes blast damage. Both the overpressure and the dynamic pressure reach to their maximum values upon the arrival of the shock wave. They then decay over a period ranging from a few tenths of a second to several seconds, depending on the blast’s strength and the yield.


Overpressure

Blast effects are usually measured by the amount of overpressure, the pressure in excess of the normal atmospheric value, in pounds per square inch (psi).

After 10 seconds, when the fireball of a 1-megaton nuclear weapon has attained its maximum size (5,700 feet across), the shock front is some 3 miles farther ahead. At 50 seconds after the explosion, when the fireball is no longer visible, the blast wave has traveled about 12 miles. It is then traveling at about 784 miles per hour, which is slightly faster than the speed of sound at sea level.

Peak overpressure Maximum Wind Speed
50 psi 934 mph
20 psi 502 mph
10 psi 294 mph
5 psi 163 mph
2 psi 70 mph
As a general guide, city areas are completely destroyed by overpressures of 5 psi, with heavy damage extending out at least to the 3 psi contour.

These many different effects make it difficult to provide a simple rule of thumb for assessing the magnitude of injury produced by different blast intensities. A general guide is given below:

Overpressure Physical Effects
20 psi Heavily built concrete buildings are severely damaged or demolished.
10 psi Reinforced concrete buildings are severely damaged or demolished.
Most people are killed.
5 psi Most buildings collapse.
Injuries are universal, fatalities are widespread.
3 psi Residential structures collapse.
Serious injuries are common, fatalities may occur.
1 psi Window glass shatters
Light injuries from fragments occur.


Blast Effects on Humans

Blast damage is caused by the arrival of the shock wave created by the nuclear explosion. Humans are actually quite resistant to the direct effect of overpressure. Pressures of over 40 psi are required before lethal effects are noted.

The danger from overpressure comes from the collapse of buildings that are generally not as resistant. Urban areas contain many objects that can become airborne, and the destruction of buildings generates many more. The collapse of the structure above can crush or suffocate those caught inside. Serious injury or death can also occur from impact after being thrown through the air.



Blast effects on a concrete building at Hiroshima.


The blast also magnifies thermal radiation burn injuries by tearing away severely burned skin. This creates raw open wounds that readily become infected.


The Mach Stem

If the explosion occurs above the ground, when the expanding blast wave strikes the surface of the earth, it is reflected off the ground to form a second shock wave traveling behind the first. This reflected wave travels faster than the first, or incident, shock wave since it is traveling through air already moving at high speed due to the passage of the incident wave. The reflected blast wave merges with the incident shock wave to form a single wave, known as the Mach Stem. The overpressure at the front of the Mach wave is generally about twice as great as that at the direct blast wave front.




A diagram of the Mach effect.


At first the height of the Mach Stem wave is small, but as the wave front continues to move outward, the height increases steadily. At the same time, however, the overpressure, like that in the incident wave, decreases because of the continuous loss of energy and the ever-increasing area of the advancing front. After about 40 seconds, when the Mach front from a 1-megaton nuclear weapon is 10 miles from ground zero, the overpressure will have decreased to roughly 1 psi.


Thermal Radiation

A primary form of energy from a nuclear explosion is thermal radiation. Initially, most of this energy goes into heating the bomb materials and the air in the vicinity of the blast. Temperatures of a nuclear explosion reach those in the interior of the sun, about 100,000,000° Celsius, and produce a brilliant fireball.



The fireball shortly after detonation.


Two pulses of thermal radiation emerge from the fireball. The first pulse, which lasts about a tenth of a second, consists of radiation in the ultraviolet region. The second pulse which may last for several seconds, carries about 99 percent of the total thermal radiation energy. It is this radiation that is the main cause of skin burns and eye injuries suffered by exposed individuals and causes combustible materials to break into flames.

Thermal radiation damage depends very strongly on weather conditions. Clouds or smoke in the air can considerably reduce effective damage ranges versus clear air conditions.


The Fireball

The fireball, an extremely hot and highly luminous spherical mass of air and gaseous weapon residues, occurs within less than one millionth of one second of the weapon’s detonation. Immediately after its formation, the fireball begins to grow in size, engulfing the surrounding air. This growth is accompanied by a decrease in temperature because of the accompanying increase in mass. At the same time the fireball rises, like a hot-air balloon. Within seven-tenths of one millisecond from the detonation, the fireball from a 1-megaton weapon is about 440 feet across, and this increases to a maximum value of about 5,700 feet in 10 seconds. It is then rising at a rate of 250 to 350 feet per second. After a minute, the fireball has cooled to such an extent that it no longer emits visible radiation. It has then risen roughly 4.5 miles from the point of burst.





The Mushroom Cloud

As the fireball increases in size and cools, the vapors condense to form a cloud containing solid particles of the weapon debris, as well as many small drops of water derived from the air sucked into the rising fireball.



The early formation of the mushroom cloud.


Depending on the height of burst, a strong updraft with inflowing winds, called “afterwinds,” are produced. These afterwinds can cause varying amounts of dirt and debris to be sucked up from the earth’s surface into the cloud. In an air burst with a moderate (or small) amount of dirt and debris drawn up into the cloud, only a relatively small proportion become contaminated with radioactivity. For a burst near the ground, however, large amounts of dirt and debris are drawn into the cloud during formation.

The color of the cloud is initially red or reddish brown, due to the presence of nitrous acid and oxides of nitrogen. As the fireball cools and condensation occurs, the color changes to white, mainly due to the water droplets (as in an ordinary cloud).

The cloud consists chiefly of very small particles of radioactive fission products and weapon residues, water droplets, and larger particles of dirt and debris carried up by the afterwinds.

The eventual height reached by the radioactive cloud depends upon the heat energy of the weapon and upon the atmospheric conditions. If the cloud reaches the tropopause, about 6-8 miles above the Earth’s surface, there is a tendency for it to spread out. But if sufficient energy remains in the radioactive cloud at this height, a portion of it will ascend into the more stable air of the stratosphere.



The mushroom cloud forming at the Nevada Test Site.


The cloud attains its maximum height after about 10 minutes and is then said to be “stabilized.” It continues to grow laterally, however, to produce the characteristic mushroom shape. The cloud may continue to be visible for about an hour or more before being dispersed by the winds into the surrounding atmosphere where it merges with natural clouds in the sky.


Thermal Pulse Effects

One of the important differences between a nuclear and conventional weapon is the large proportion of a nuclear explosion’s energy that is released in the form of thermal energy. This energy is emitted from the fireball in two pulses. The first is quite short, and carries only about 1 percent of the energy; the second pulse is more significant and is of longer duration (up to 20 seconds).

The energy from the thermal pulse can initiate fires in dry, flammable materials, such as dry leaves, grass, old newspaper, thin dark flammable fabrics, etc. The incendiary effect of the thermal pulse is also substantially affected by the later arrival of the blast wave, which usually blows out any flames that have already been kindled. However, smoldering material can reignite later.

The major incendiary effect of nuclear explosions is caused by the blast wave. Collapsed structures are much more vulnerable to fire than intact ones. The blast reduces many structures to piles of kindling, the many gaps opened in roofs and walls act as chimneys, gas lines are broken open, storage tanks for flammable materials are ruptured. The primary ignition sources appear to be flames and pilot lights in heating appliances (furnaces, water heaters, stoves, etc.). Smoldering material from the thermal pulse can be very effective at igniting leaking gas.

Thermal radiation damage depends very strongly on weather conditions. Cloud cover, smoke, or other obscuring material in the air can considerably reduce effective damage ranges versus clear air conditions.

Thermal radiation also affects humans both directly – by flash burns on exposed skin – and indirectly – by fires started by the explosion.


Firestorms

Under some conditions, the many individual fires created by a nuclear explosion can coalesce into one massive fire known as a “firestorm.” The combination of many smaller fires heats the air and causes winds of hurricane strength directed inward toward the fire, which in turn fan the flames. For a firestorm to develop:

There must be at least 8 pounds of combustibles per square foot.
At least one-half of the structures in the area are on fire simultaneously.
There is initially a wind of less than 8 miles per hour.
The burning area is at least 0.5 square miles.
In Hiroshima, a firestorm did develop and about 4.4 square miles were destroyed. Although there was some damage from uncontrolled fires at Nagasaki, a firestorm did not develop. One reason for this was the difference in the terrain. Hiroshima is relatively flat, while Nagasaki has uneven terrain.



The firestorm at Hiroshima.

Firestorms can also be caused by conventional bombing. During World War II, the cities of Dresden, Hamburg, and Tokyo all suffered the effects of firestorms.


Flash Burns

Flash burns are one of the serious consequences of a nuclear explosion. Flash burns result from the absorption of radiant energy by the skin of exposed individuals. A distinctive feature of flash burns is the fact they are limited to exposed areas of the skin facing the explosion.



The burns are in a pattern corresponding to the dark portions of the kimono
she was wearing at the time of the explosion.



A 1-megaton explosion can cause first-degree burns (a bad sunburn) at a distance of about 7 miles, second-degree burns (producing blisters and permanent scars) at distances of about 6 miles, and third-degree burns (which destroy skin tissue) at distances up to 5 miles. Third-degree burns over 24 percent of the body, or second-degree burns over 30 percent, will result in serious shock, and will probably prove fatal unless prompt, specialized medical care is available.

It has been estimated that burns caused some 50 percent of the deaths at Hiroshima and Nagasaki.


Flash blindness

Flash blindness is caused by the initial brilliant flash of light produced by the nuclear detonation. The light is received on the retina than can be tolerated, but less than is required for irreversible injury. The retina is particularly susceptible to visible and short wavelength infrared light. The result is a bleaching of visual pigment and temporary blindness. Vision is completely recovered as the pigment is regenerated.

During the daylight hours, flash blindness does not persist for more than 2 minutes, but generally lasts a few seconds. At night, when the pupil is dilated, flashblindness will last for a longer period of time.

A 1-megaton explosion can cause flash blindness at distances as great as 13 miles on a clear day, or 53 miles on a clear night. If the intensity is great enough, a permanent retinal burn will result.

Retinal injury is the most far-reaching injury effect of nuclear explosions, but it is relatively rare since the eye must be looking directly at the detonation. Retinal injury results from burns in the area of the retina where the fireball image is focused.


Nuclear Radiation

The release of radiation is a phenomenon unique to nuclear explosions. There are several kinds of radiation emitted; these types include gamma, neutron, and ionizing radiation, and are emitted not only at the time of detonation (initial radiation) but also for long periods of time afterward (residual radiation).

Initial Nuclear Radiation

Initial nuclear radiation is defined as the radiation that arrives during the first minute after an explosion, and is mostly gamma radiation and neutron radiation.

The level of initial nuclear radiation decreases rapidly with distance from the fireball to where less than one roentgen may be received five miles from ground zero. In addition, initial radiation lasts only as long as nuclear fission occurs in the fireball. Initial nuclear radiation represents about 3 percent of the total energy in a nuclear explosion.

Though people close to ground zero may receive lethal doses of radiation, they are concurrently being killed by the blast wave and thermal pulse. In typical nuclear weapons, only a relatively small proportion of deaths and injuries result from initial radiation.

Residual Nuclear Radiation

The residual radiation from a nuclear explosion is mostly from the radioactive fallout. This radiation comes from the weapon debris, fission products, and, in the case of a ground burst, radiated soil.

There are over 300 different fission products that may result from a fission reaction. Many of these are radioactive with widely differing half-lives. Some are very short, i.e., fractions of a second, while a few are long enough that the materials can be a hazard for months or years. Their principal mode of decay is by the emission of beta particles and gamma radiation.


Source: www.atomicarchive.com/Effects/effects15.shtml

Nuclear Power – Better Not

Posted in Enviroment on January 22, 2011 by Aksyn Elek




Nuclear Power – Why Not?


Blogpost by Justin – January 14, 2011


(This post is by Dr Rianne Teule, Senior Climate and Energy Campaigner for Greenpeace International)


The most common question asked when I’m at a party and someone finds out I work for Greenpeace is: “What about nuclear energy?”
Most people don’t want to know about blocking whaling ships in an inflatable, or whether I recently climbed a smokestack of a coal-fired power station. No, they want to discuss nuclear.
So I say that Greenpeace has always fought – and will continue to fight – against nuclear power because it is expensive, poses an unacceptable risk to the environment and to humanity, and will not help in solving the climate problem.
“But nuclear energy is clean!” No.
Nuclear energy might cause less carbon emissions than fossil fuels, but it is far from clean. It produces radioactive waste and causes radioactive pollution all over the world. Nuclear power gambles with people’s health and the environment from the very beginning of the nuclear chain – mining for uranium. I spoil the party by telling people about my rather depressing visit to Niger, where uranium mining contaminates the air, water and soil, and creates huge volumes of radioactive waste. On top of that, nuclear power creates tens of thousands of tons of lethal waste, which is radioactive for hundreds of thousands of years. No solution has yet been found for the safe and secure storage of the dangerous waste over such a long time period, which potentially spans many Ice Ages.
“But there are new and safer nuclear technologies!” No.
There are no new technologies that offer a solution for the waste or guarantee the safety of nuclear plants. This time i share my experiences of visiting the area around the Chernobyl nuclear power plant that exploded in 1986 – large areas, even up to more than 100km from the plant are still unsafe to live. And a continuous stream of incidents and accidents in nuclear reactors and other nuclear installations prove how vulnerable the technology is.
In September 2010, 79 workers at Koeberg nuclear power plant near Cape Town were exposed to significant levels of radioactive cobalt. The alarms did not go off, and the incident was only detected after the workers ended their shift. Currently one of the Koeberg reactors is shut down because one or more defective fuel rods caused higher levels of radioactivity in the reactor.
In December 2010, more than 30 million litres of radioactive sludge from three cracked waste pools has leaked into the environment at a uranium mine in Niger, operated by French nuclear company AREVA. At least 20 hectares of land are contaminated.
The Nuclear Regulatory Commission in the US found that radioactive tritium is leaking from at least 27 of the nation’s 104 nuclear reactors, raising concerns about how it is escaping from the aging nuclear plants.
The number of ‘significant events’ or incidents in nuclear facilities in France has increased over the last decade.
“But nuclear power is cheap!” No.
Nuclear power is often described as “the most expensive way to boil water.” Despite what the nuclear industry tells us, building enough nuclear power stations to make a meaningful reduction in greenhouse gas emissions would cost trillions of dollars. The construction costs of new nuclear power plants in Finland and France are soaring.
And we so desperately need these resources to implement real climate change solutions! Nuclear power undermines the real solutions to climate change by diverting urgently needed investments away from clean, renewable sources of energy and energy efficiency.
Nuclear power is a bad idea. And not a very stimulating subject to discuss at a party…


 

Source: http://www.greenpeace.org/international/en/news/Blogs/nuclear-reaction/nuclear-power-why-not/blog/32327

Radiations Induced Mutations

Posted in Enviroment on January 22, 2011 by Aksyn Elek



 

18 Mar, 02:21 PM

 

The animals living in the contaminated area near the site of Chernobyl nuclear disaster in Ukraine are much worse affected by radioactive pollution than it’s generally thought, says a study made public Wednesday.
The study illustrates that the numbers of bumble-bees, butterflies, spiders, grasshoppers and other invertebrates were lower in contaminated sites than other areas because of high levels of radiation left over from the blast more than 20 years ago, Reuters reports.

The findings challenge earlier research that suggested animal populations were rebounding around the site of the Chernobyl explosion in Ukraine, which forced thousands to abandon their homes and evacuate the area.

Estimates of the number of deaths directly related to the accident vary. The World Health Organization estimates the figure at 9,000, while the environmental group Greenpeace predicts an eventual death toll of 93,000.

“We were amazed to see that there had been no studies on this subject,” Anders Moller, a researcher at the National Center for Scientific Research in France, who led the study, said in a telephone interview.

“Ours was the first study to focus on the abundance of animal populations.”

Researchers said they had compared animal populations in radioactive areas with less contaminated plots and found that some were nearly depleted of animal life.

“There are areas with an abundance of 100 animals per square meter,” Moller said. “And then there are areas with less than one specimen per square meter on average; the same goes for all groups of species.”

The researchers also found that animals living near the Chernobyl reactor — which was covered in a protective shell after it exploded in April 1986 — had more deformities, including discoloration and stunted limbs, than normal.

“Usually (deformed) animals get eaten quickly, as it’s hard to escape if your wings are not the same length,” Moller said. “In this case we found a high incidence of deformed animals.”

The findings challenge the view of Chernobyl as ecologically sound, despite the fact that Ukrainian officials have turned it into a nature reserve, with wolves, bison and bears.

Earlier research into the area ignored the fact that animal populations had grown unimpeded in the absence of humans for many years after the blast, Moller said.

“We wanted to ask the question: Are there more or fewer animals in the contaminated areas? Clearly there were fewer,” said Moller, who has worked on Chernobyl since 1991.

While researchers focused on the 30 kilometer radius around the Chernobyl reactor, the fallout from the explosion covered a vast swathe of Eastern Europe, including parts of Russia, Ukraine and Belarus.

The findings probably apply to those areas as well, Moller said, adding that any decontamination effort was unlikely due to the extent of the fallout.


Source: www.mosnews.com/world/2009/03/18/chernobyl

 

 

Check why Ionizing Radiations can cause severe mutations, transformations and DNA alterations >>> http://enhs.umn.edu/hazards/hazardssite/radon/radonmolaction.html

Chernobyl Nuclear Accident

Posted in Enviroment on January 22, 2011 by Aksyn Elek





Date and Time of the Chernobyl Nuclear Accident:

The Chernobyl nuclear accident occurred on Saturday, April 26, 1986, at 1:23:58 a.m. local time.
Location of the Chernobyl Nuclear Power Station:

The V.I. Lenin Memorial Chernobyl Nuclear Power Station was located in Ukraine, near the town of Pripyat, which had been built to house power station employees and their families. The power station was in a wooded, marshy area near the Ukraine-Belarus border, approximately 18 kilometers northwest of the city of Chernobyl and 100 km north of Kiev, the capital of Ukraine.

Background on the Chernobyl Nuclear Accident:

The Chernobyl Nuclear Power Station included four nuclear reactors, each capable of producing one gigawatt of electric power. At the time of the accident, the four reactors produced about 10 percent of the electricity used in Ukraine.
Construction of the Chernobyl power station began in the 1970s. The first of the four reactors was commissioned in 1977, and Reactor No. 4 began producing power in 1983. When the accident occurred in 1986, two other nuclear reactors were under construction.

The Chernobyl Nuclear Accident:

On April 26, 1986, the operating crew planned to test whether the Reactor No. 4 turbines could produce enough energy to keep the coolant pumps running until the emergency diesel generator was activated in case of an external power loss. During the test, power surged unexpectedly, causing an explosion and driving temperatures in the reactor to more than 2,000 degrees Celsius—melting the fuel rods, igniting the reactor’s graphite covering, and releasing a cloud of radiation into the atmosphere.

Causes of the Chernobyl Nuclear Accident:

The precise causes of the accident are still uncertain, but it is generally bhttps://aksynelek.wordpress.com/?p=34&preview=trueelieved that the series of incidents that led to the explosion, fire and nuclear meltdown at Chernobyl was caused by a combination of reactor design flaws and operator error.

Loss of Life from the Chernobyl Nuclear Accident:

By mid-2005, fewer than 60 deaths could be linked directly to Chernobyl—mostly workers who were exposed to massive radiation during the accident or children who developed thyroid cancer.
Estimates of the eventual death toll from Chernobyl vary widely. A 2005 report by the Chernobyl Forum—eight U.N. organizations—estimated the accident eventually would cause about 4,000 deaths. Greenpeace places the figure at 93,000 deaths, based on information from the Belarus National Academy of Sciences.

Physical Health Effects Linked to the Chernobyl Nuclear Accident:

The Belarus National Academy of Sciences estimates 270,000 people in the region around the accident site will develop cancer as a result of Chernobyl radiation and that 93,000 of those cases are likely to be fatal.
Another report by the Center for Independent Environmental Assessment of the Russian Academy of Sciences found a dramatic increase in mortality since 1990—60,000 deaths in Russia and an estimated 140,000 deaths in Ukraine and Belarus—probably due to Chernobyl radiation.

Psychological Effects of the Chernobyl Nuclear Accident:

The biggest challenge facing communities still coping with the fallout of Chernobyl is the psychological damage to 5 million people in Belarus, Ukraine and Russia.
“The psychological impact is now considered to be Chernobyl’s biggest health consequence,” said Louisa Vinton, of the UNDP. “People have been led to think of themselves as victims over the years, and are therefore more apt to take a passive approach toward their future rather than developing a system of self-sufficiency.”

Countries and Communities Affected by the Chernobyl Nuclear Accident:

Seventy percent of the radioactive fallout from Chernobyl landed in Belarus, affecting more than 3,600 towns and villages, and 2.5 million people. The radiation contaminated soil, which in turn contaminates crops that people rely on for food. Many regions in Russia, Belarus and Ukraine are likely to be contaminated for decades.
Radioactive fallout carried by the wind was later found in sheep in the UK, on clothing worn by people throughout Europe, and in rain in the United States.

Chernobyl Status and Outlook:

The Chernobyl accident cost the former Soviet Union hundreds of billions of dollars, and some observers believe it may have hastened the collapse of the Soviet government.
After the accident, Soviet authorities resettled more than 350,000 people outside the worst areas, including all 50,000 people from nearby Pripyat, but millions of people continue to live in contaminated areas.

After the breakup of the Soviet Union, many projects intended to improve life in the region were abandoned, and young people began to move away to pursue careers and build new lives in other places.

“In many villages, up to 60 percent of the population is made up of pensioners,” said Vasily Nesterenko, director of the Belrad Radiation Safety and Protection Institute in Minsk. “In most of these villages, the number of people able to work is two or three times lower than normal.”

After the accident, Reactor No. 4 was sealed, but the Ukranian government allowed the other three reactors to keep operating because the country needed the power they provided. Reactor No. 2 was shut down after a fire damaged it in 1991, and Reactor No. 1 was decommissioned in 1996. In November 2000, the Ukranian president shut down Reactor No. 3 in an official ceremony that finally closed the Chernobyl facility.

But Reactor No. 4, which was damaged in the 1986 explosion and fire, is still full of radioactive material encased inside a concrete barrier, called a sarcophagus, that is aging badly and needs to be replaced. Water leaking into the reactor carries radioactive material throughout the facility and threatens to seep into the groundwater.

The sarcophagus was designed to last about 30 years, and current designs would create a new shelter with a lifetime of 100 years. But radioactivity in the damaged reactor would need to be contained for 100,000 years to ensure safety. That is a challenge not only for today, but for many generations to come.

Source: http://environment.about.com/od/chernobyl/p/chernobyl.htm





End the Nuclear Age

Posted in Enviroment on January 22, 2011 by Aksyn Elek



Greenpeace has always fought – and will continue to fight – vigorously against nuclear power because it is an unacceptable risk to the environment and to humanity. The only solution is to halt the expansion of all nuclear power, and for the shutdown of existing plants.



Nastya, from Belarus was only three years old when she was diagnosed with cancer of the uterus and lungs. According to local doctors the region has seen a huge increase in childhood cancer cases since the Chernobyl disaster.


We need an energy system that can fight climate change, based on renewable energy and energy efficiency. Nuclear power already delivers less energy globally than renewable energy, and the share will continue to decrease in the coming years.

Despite what the nuclear industry tells us, building enough nuclear power stations to make a meaningful reduction in greenhouse gas emissions would cost trillions of dollars, create tens of thousands of tons of lethal high-level radioactive waste, contribute to further proliferation of nuclear weapons materials, and result in a Chernobyl-scale accident once every decade. Perhaps most significantly, it will squander the resources necessary to implement meaningful climate change solutions. (Briefing: Climate change – Nuclear not the answer.)



“Nuclear power plants are, next to nuclear warheads themselves, the most dangerous devices that man has ever created. Their construction and proliferation is the most irresponsible, in fact the most criminal act ever to have taken place on this planet.”

Patrick Moore, Assault on Future Generations, 1976


The Nuclear Age began in July 1945 when the US tested their first nuclear bomb near Alamogordo, New Mexico. A few years later, in 1953, President Eisenhower launched his “Atoms for Peace” Programme at the UN amid a wave of unbridled atomic optimism.

But as we know there is nothing “peaceful” about all things nuclear. More than half a century after Eisenhower’s speech the planet is left with the legacy of nuclear waste. This legacy is beginning to be recognised for what it truly is.

Things are moving slowly in the right direction. In November 2000 the world recognised nuclear power as a dirty, dangerous and unnecessary technology by refusing to give it greenhouse gas credits during the UN Climate Change talks in The Hague. Nuclear power was dealt a further blow when a UN Sustainable Development Conference refused to label nuclear a sustainable technology in April 2001.

The risks from nuclear energy are real, inherent and long-lasting.



Source: http://www.greenpeace.org/international/en/campaigns/nuclear