Radioactive debris

Krey, P. W. Krajewski, B. 1970. Comparison of atmospheric transport model calculations with observation of radioactive debris. Journal of Geophysical Research, 75, 2901-2908. 

But for chemists, the hydrogen bomb tests had a happier fallout too. Scientists at the Mike test collected coral from a nearby atoll contaminated with radioactive debris, and sent it to Berkeley for analysis. There the nuclear chemists found two new elements, with atomic numbers 99 and 100. They were named after two of the century s most creative physicists einsteinium and fermium. 

Radioactive Debris in Cows. Nuclear detonations produce a complex mixture of radionuclides that includes both the fission products and those induced by neutron activation. Experiments relating to such events... 

Figure 18. Gamma-ray spectra from various biological materials from a dairy cow that had been previously fed radioactive debris collected at the site of a nuclear detonation...

A knowledge of the size distribution function of the radioactive debris and the specific activity of individual fission product chains as a function of particle size suffice to define many important radiological properties of the land-surface nuclear explosion. If is the function of a radionuclide or fission mass chain distributed between particle sizes Di and D2, then... 

If the initial distribution of radioactive debris is known spatially, Equations 1 and 2 suffice to define the partition of radioactive debris between local and long range fallout, the decay rate of radioactive debris in a given size interval, and other properties of the radiation fallout field. 

The character of the radioactive debris from a land surface explosion is determined largely by the extent of mixing between the extraneous debris injected into the cloud and the fission product radioactivities. Within the early cloud there is a well developed toroidal circulation (5), which is clearly evident in the case of air bursts and large yield surface bursts. In low yield surface explosions it may be obscured quickly by the dirt cloud and by rapid damping of a systematic circulation. 

The size distribution of the radioactive debris containing the majority of the fission products may bear little relationship to the size distribution of the environmental soil. Vaporization, agglomeration, condensation, and coagulation will probably lead to particles smaller than and larger than those found in the soil. A striking demonstration of this is found in the size distribution of radioactive debris of a low yield explosion over an alluvial salt bed in Nevada (6). While the mean diameter of the pre-shot soil particles was about 6/, the prompt fallout contained many intensely radioactive particles of 1000/ or greater. 

The topographic distribulion of fallout is divided into three categories called (I) local (or close-in) (2) tropospheric (or intermediate) and 3i stratospheric or worldwide) fallout. No distinct boundaries exist between these categories. The distinction between local and tropospheric fallout is a function of dislance from source to point of deposit The primary dislinclion between tropospheric and stratospheric fallout is the place of injection of the dehris into the atmosphere, above or below the iropopause. Whether the radioactive debris from a nuclear weapon becomes tropospheric or stratospheric fallout depends on yield, height, and lalilude of burst (the height of the iropopause is a function of latitude). 

The daughter nuclide may be stable or unstable (radioactive), debris disk a circumstellar disk in which the majority of the dust is not derived from the collapsing molecular cloud, but from the collisions of minor bodies in the disk. The typical masses and optical depths of these disks are several orders of magnitudes lower than those typical to accretion disks, desorption changing from an adsorbed state on a surface to a gaseous or liquid state. 

Everyone s worst fears about nuclear power became a reality in tlie later part of April 1986. A large Soviet reactor - unit number 4 at Chernobyl, 80 utiles nortli of Kiev, and only 3 years old blew out and burned, spewing radioactive debris over much of Europe. Radiation levels increased from Sweden to Britain, tlirough Poland, and as far soutli as Italy. The damage caused to tlie environment far surpassed tlial due to tlie accident at Tliree Mile Island. 

Einsteinium (Z = 99) and fermium (Z = 100) were identified in 1952 and 1953, respectively, by Ghiorso and others in the radioactive debris of the first thermonuclear explosion. Hints of the formation of these elements were found in dust samples from the remotely controlled aircrafts used in this test. Then, the elements were isolated by processing larger amounts of the radioactive coral material from the test site and named in honour of Einstein and Feimi. The elements had been formed by multineutron capture,... 

When a nuclear weapon is tested in the atmosphere, the large amount of radioactive debris produced in the explosion is freely released into the environment. This radioactive debris, consisting of gases and particulate radionuclides, disperses with atmospheric circulation and is transported and deposited throughout the world. People everywhere are then exposed to radiation from radionuclides in the air and on the ground and also from radionuclides that enter the body by inhalation of air and by ingestion of food and water. 

Fig. 10.2. Partitioning of radioactive debris for a 1 Mt explosion in equatorial region.

Following injection of radioactive debris into the atmosphere, the subsequent dispersion and eventual deposition of the material onto the earth s surface are determined by mass air circulation patterns in the atmosphere. These patterns have been established from meteorological studies and from measurements of the behaviour of fallout radionuclides. The injection of radionuclides into the atmosphere by atmospheric weapons testing has provided a unique tracer experiment, which has helped to provide understanding of the atmospheric processes. 

The partitioning of radioactive debris in the troposphere and stratospheric regions is determined by the total explosive yield and the height and latitude of the burst. The total yield is the sum of the fission and fusion yields of the device. The production of important fallout radionuclides is determined by the fission yield of the weapon. Smaller yield nuclear explosions are produced by fission reactions, while larger yield explosions result from boosted fission or thermonuclear fusion reactions. Of the total yield of all atmospheric tests of440 Mt, an estimated 182 Mt, or about 40% of the total, was fission yield and the remainder was fusion yield. The contributions of countries conducting atmospheric tests to the total fission yield is shown in Table 10.3. 

Not all of the radioactive debris produced in nuclear tests is carried into the troposphere and stratosphere and dispersed as global fallout. For tests conducted on the ground or water surface, an estimated 50% of the debris remains in the local vicinity of the test site. Many tests conducted by the United States were surface explosions. Other... 

Some air pollutants are transported far beyond their points of release. For example, otherwise pristine areas have received acid precipitation originating from industrial smokestack emissions hundreds of miles away. Dust from the Sahara Desert in Africa has been detected in South America, and radioactive debris from the Chernobyl nuclear reactor meltdown has been deposited in countries throughout Europe. 

Both human and mechanical errors led to overheating of the reaction chamber at the Chernobyl nuclear plant in the former Soviet Union in 1986. Water used to cool the chamber decomposed into hydrogen and oxygen gas, which exploded and blew the roof off the building that housed the reactor. A large amount of radioactive debris was released and traveled as far away as Scandinavia and England. Even now, almost 1000 square miles around the plant are considered too radioactive for permanent habitation. 

The sun is not commonly considered a star and few would think of stars as nuclear reactors. Yet, that is the way it is, and even our own world is made out of the fall-out from stars that blew up and spewed radioactive debris into the nascent solar system. 

On November 1,1952, the USA exploded a thermonuclear bomb over the atoll Eniwetok in the Pacific. A few hundreds of kilograms of the soil from the explosion site were collected with all possible precautions and taken to the USA. A group of scientists headed by Seaborg and Giorso carefully studied this radioactive debris. It was found to contain... 

FaUout (nuclear)—Minute particles of radioactive debris that descend slowly from the atmosphere after a nuclear explosion. 

The type and amount of fallout vary with the location of the point of burst in relation to the surface of the earth. Following an underwater burst, for example, besides massive local atmospheric fallout, the radioactive debris returns in a downpour, or rainout, within minutes after the explosion, with considerable environmental consequences to aquatic life additionally, the surrounding area is shrouded by a lethal radioactive mist. 

Einsteinium (Es) and fermium (Fm) were identified in 1952 in the radioactive debris from the Mike thermonuclear explosion that took place in the Pacific. Ion-exchange separation was applied, and the new elements, einsteinium and fermium, were isolated by processing larger amounts of the radioactive coral material (Ghiorso et al. 1955a). Chemical identification was made by ion-exchange separations, while isotopic assignments were made as the result of the... 

Atmospheric tests From the first test in New Mexico on July 16,1945, to the last atmospheric test at Lop Nor on October 16,1980, 543 nuclear tests were carried out in the atmosphere, and enormous amounts of radionuclides were released. The radioactive debris is deposited locally (up to 100-200 km from ground zero), regionally (2,000-3,000 km), or released into the troposphere and/or stratosphere resulting in global dispersion (O Table 55.24). 

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