Radioactive particles from nuclear weapons

The Characterization of Radioactive Particles from Nuclear Weapons Tests... 

Gasiev, Y. L, Malakhov, S. G., Nazarov, L. E. and Silantiev, A. N., 1966 The size distribution of radioactive particles from nuclear weapon tests and their transport in the atmosphere. Tellus 18,474-485. 

I. Gasiev, S. G, Malakhov, L. G. Nazarov and A. N, Silantiev, The Size Distribution of Radioactive Particles from Nuclear Weapons Tests and Their Transport in the Atmosphere, Tellus 18 474 (1965). 

Lockhart, L.,B., Patterson, R.L. Saunders, A.W. (1965) Distribution of airborne activity with particle size. In Radioactive Fallout from Nuclear Weapon Tests, ed. A.W. Klement Jr. CONF 765. N.T.I.S. Springfield, Va. 

Table II summarizes some of the features of the radioactive fallout processes in geophysical and astronomical settings. It seems that similarities do exist between the processes of formation of single particles from nuclear explosions and formation of the solar system from the debris of supernova explosion. We may be able to learn much more about the origin of the earth, by further investigating the process of radioactive fallout from the nuclear weapons tests.

FALLOUT (Radioactive . The term fallout generally has been used to refer to particulate mutter that is thrown into the atmosphere by a nuclear process of short time duration. Primary examples are nuclear weapon debris and effluents from a nuclear reactor excursion. The name fallout is applied both to matter that is aloll and to matter that has been deposited on the surface of the earfh. Depending on the conditions of formation, this material ranges in texture from an aerosol to granules uf considerable size. The aerodynamic principles governing tls deposition are the same as for any Other material of comparable physical nature that is thrown into the air. such as volcanic ash or particles from chimneys. Therefore, many of the principles learned in. studies of fallout from nuclear weapons can be applied lo studies of other particulate pollution in the atmosphere. 

Although much of the preceding discussion involved the synthesis of new molecules by organic and inorganic chemists, there is another area of chemistry in which such creation is important—the synthesis of new atoms. The periodic table lists elements that have been discovered and isolated from nature, but a few have been created by human activity. Collision of atomic particles with the nuclei of existing atoms is the normal source of radioactive isotopes and of some of the very heavy elements at the bottom of the periodic table. Indeed nuclear chemists and physicists have created some of the most important elements that are used for nuclear energy and nuclear weapons, plutonium in particular. 

Of the various ionizing particulate radiations, the most important in terms of likelihood for human exposure are alpha particles, beta particles, protons, and neutrons. Alpha and beta particles occur as a result of the radioactive decay of unstable atoms. Neutrons generally result from nuclear reactions, such as nuclear fission (as in nuclear reactors and fission-based nuclear weapons) and charged-particle activation of target atoms (as with some accelerator-produced... 

There are essentially three sources of radioactive elements. Primordial nuclides are radioactive elements whose half-lives are comparable to the age of our solar system and were present at the formation of Earth. These nuclides are generally referred to as naturally occurring radioactivity and are derived from the radioactive decay of thorium and uranium. Cosmogenic nuclides are atoms that are constantly being synthesized from the bombardment of planetary surfaces by cosmic particles (primarily protons ejected from the Sun), and are also considered natural in their origin. The third source of radioactive nuclides is termed anthropogenic and results from human activity in the production of nuclear power, nuclear weapons, or through the use of particle accelerators. 

As part of the biogeochemical cycle, the injection of iodine-containing gases into the atmosphere, and their subsequent chemical transformation therein, play a crucial role in environmental and health aspects associated with iodine - most importandy, in determining the quantity of the element available to the mammalian diet. This chapter focuses on these processes and the variety of gas- and aerosol-phase species that constitute the terrestrial iodine cycle, through discussion of the origin and measurement of atmospheric iodine in its various forms ( Sources and Measurements of Atmospheric Iodine ), the principal photo-chemical pathways in the gas phase ( Photolysis and Gas-Phase Iodine Chemistry ), and the role of aerosol uptake and chemistry and new particle production ( Aerosol Chemistry and Particle Formation ). Potential health and environmental issues related to atmospheric iodine are also reviewed ( Health and Environment Impacts ), along with discussion of the consequences of the release of radioactive iodine (1-131) into the air from nuclear reactor accidents and weapons tests that have occurred over the past half-century or so ( Radioactive Iodine Atmospheric Sources and Consequences ). 

Fission. The splitting of an atomic nucleus into two fragments that usually releases neutrons and y rays. Eission may occur spontaneously or may be induced by capture of bombarding particles. Primary fission products usually decay by particle emission to radioactive daughter products. The chain reaction that may result in controlled burning of nuclear fuel or in an uncontrolled nuclear weapons explosion results from the release of 2 or 3 neutrons/fission. Neutrons cause additional fissile nuclei in the vicinity to fission, producing still more neutrons, in turn producing still... 

The terrestrial component of the dust particles embedded in the ice consists of volcanic ash, finegrained dust derived from soil on the continents, carbon particles released by forest fires, biogenic particles (e.g., the skeletons of diatoms, seeds, and pollen grains), aerosol particles of atmospheric origin, including sea-spray particles that nucleate snow flakes (Section 17.10). In addition, the uppermost layer of snow and fim that was deposited after the start of the Industrial Revolution (i.e., post ad 1850) contains anthropogenic detritus such as flakes of metal, paint, and plastics, fly-ash particles and other combustion products, fibers (composed of wood, cotton, and synthetics), industrial contaminants (e.g., lead), and radioactive nuchdes released by the testing of nuclear weapons and by the operation of nuclear reactors (Faure et al. 1997). 

Terrorism by way of radioactive materials can come in several forms. If the radioactive isotope is a fissionable material (material that can be used to create a chain reaction that could result in a nuclear explosion), such as some plutonium and uranium isotopes, it is possible that it could be combined into a nuclear weapon. Otherwise the radioactive material might be dispersed by a conventional explosion or by airborne means such as a powder or spray from an aircraft. A building could be contaminated by placing finely ground radioactive particles or powder in the ventilation system. The material could also be spread by hand (more dangerous for the terrorist) or mailed in a package or envelope. 

Strontium ( Sr) is a fission product that is common in spent fuel. Nuclear fuel processing, above ground nuclear weapons testing, and nuclear accidents are primary environmental sources of Sr. Strontium-90 also is released by nuclear power plants, submarine propulsion reactors, and radioactive waste disposal in the oceans. Sr has a half-life of roughly 29 yr. The decay products are Yt (ri/2 = 64 h, with the emission of a 546 keV maximum energy P particle) and then the stable Zr with the emission of a 2284 keV maximum energy p particle from Infre-... 

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