Accidents, nuclear

In a nuclear accident, these problems have to be dealt with as an emergency whereas in the case of the decommissioning of a nuclear plant or the disposal of laboratory chemicals the problems can be approached within a longer time-scale. 

The major problem, apart from local radioactivity, in this and the other accidents, was that large amounts of volatile fission products were widely distributed high in the atmosphere. These subsequently polluted large land areas. The main volatile elements released at Chernobyl were the noble gases (especially krypton, Kr, and xenon, Xe), iodine, I, and caesium, Cs. The caesium isotopes, caesium-134 and caesium-137, posed a particular problem. The half-life of caesium-134 is 2.06 years. 

The only practical solution in cases of this nature is to isolate the area as far as possible and to prevent contaminated products from reaching market. 

Waste management is a field that involves tlie reduction, stabilization, and ultimate disposal of waste. Waste reduction is tlie practice of minimizing file amount of material tliat requires disposal. Some of the common ways in which waste reduction is accomplished are incineration, compaction, and dewatering. The object of waste disposal is to isolate tlie material from tlie biosphere, and in the case of radioactive wtiste, allow it time to decay to sufficiently safe levels. 

As described in Chapter 1, the three largest radiological accidents of the last twenty years tire tlie explosion at Chernobyl, the partial core meltdown at Three Mile Island Unit 2, tuid the mishandling of a radioactive source in Brazil. The least publicized, but perhaps tlie most appropriate of tliese accidents, witli respect to waste management, was tlie situation in Brazil. 

Several different mechanisms, most importtuitly alplia particle, beta particle, and gamma ray emissions accomplish radioactive transformations. Each of these mechanisms is a spontaneous nuclear transformation. Tlie result of tliese transformations is the formation of different stable elements. Tlie kind of transformation that will ttike place for any given radioactive element is a function of the type of nuclear inslabilitv as well as the mass/energy relationship. The nuclear instability is dependent on the ratio of neutrons to 

An alplia p uticle is an energetic helium nucleus. The alplia particle is released from a radioactive element witli a neutron to proton ratio tliat is too low. The helium nucleus consists of two protons and two neutrons. The alplia particle differs from a helimn atom in that it is emitted witliout any electrons. The resulting daughter product from tliis tj pe of transformation lias an atomic number Uiat is two less tluin its parent and an atomic mass number tliat is four less. Below is an e. aiiiple of alpha decay using polonium (Po) polonium has an atomic mass number of 210 (protons and neutrons) and atomic number of 84. 

Beta piuticle emission occurs when an ordinary electron is ejected from tlie nucleus of an atom. 

Tlie tenns He and Pb rquesenl helium and lead, respectively. 

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Alkali AletalIodides. Potassium iodide [7681-11-0] KI, mol wt 166.02, mp 686°C, 76.45% I, forms colorless cubic crystals, which are soluble in water, ethanol, methanol, and acetone. KI is used in animal feeds, catalysts, photographic chemicals, for sanitation, and for radiation treatment of radiation poisoning resulting from nuclear accidents. Potassium iodide is prepared by reaction of potassium hydroxide and iodine, from HI and KHCO, or by electrolytic processes (107,108). The product is purified by crystallization from water (see also Feeds and feed additives Photography). 

Y. S. Sedunov, V. A. Borzilov, and N. V. Klepikova, Use of Mathematical Modeling to Estimate Formation of Contaminated Areas Resultingfrom Nuclear Accident, IAEA-SM-306/114, IAEA, Vienna, Austria, 1990. 

Arnold, L., Windscale 1957, Anatomy of a Nuclear Accident St. Martin s Press, New York, 1992. 

HS(G)63 Radiation protection offsite for emergency services m the event of a nuclear accident... 

While event trees are not so common in chemical plant PSA they are extensively used to analyze nuclear accidents, but before beginning the analysis, preliminaries that are needed are plant tamiliarity and initiator selection... 

The analysis of the consequences of nuclear accidents began with physical concepts of core melt, discussed the mathematical and code models of radionuclide release and transport within the plant to its release into the environment, models for atmospheric transport and the calculation of health effects in humans. After the probabilities and consequences of the accidents have been determined, they must be assembled and the results studied and presented to convey the meanings. 

The previous chapter described the consequences of a nuclear reactor accident. Chemical process accidents are more varied and do not usually have the energy to melt thick pressure vessels and concrete basemats. The consequences of a chemical process accident that releases a toxic plume, like Bhopal did, are calculated similarly to calculating the dose from inhalation from a radioactive plume but usually calculating chemical process accidents differ from nuclear accidents for which explosions do not occur. 

Latent cancer is calculated to be the primary risk from a nuclear accident (this may be due to the conservatism in the low-dose models). At Chernobyl, most of the deaths were from fire and impact. Chemical process risk depends on the chemicals being processed. Experience shows that processing poisons poses the highest risk to public and workers. 

WASH-740,1957, Theoretical Possibilities and Consequences of Major Nuclear Accidents at Large Nu( ar Plants, March. 

In fact, the air was not vented. The 1 -inch vent line on the air supply was choked by a wasp s nest. Although this example primarily illustrates a wrong assumption, a second factor was the inadequate indication of the state of the oxygen valve by the panel light. A similar error was a major contributor to the Three Mile Island nuclear accident. 

Nuclear accidents, while being tlie most frightening, liave not occurred often. In fact, tlicre have only been a luuidful of fatal incidents since an understanding of nuclear energy and radiation has been developed. However... 

Electrical Failures and Computer Failures Nuclear Accidents Natural Disasters... 

A much more serious nuclear accident occurred at Chernobyl in the USSR on April 26, 1986, when one of the Chernobyl units experienced a full-core meltdown. The Chernobyl accident has been called the worse disaster of the industrial age. An area comprising more than 60,000 square miles in the Ukraine and Belarus was contaminated, and more than 160,000 people were evacuated. However, wind and water have spread the contamination, and many radiation-related illnesses, birth defects, and miscarriages have been attributed to the Chernobyl disaster. 

April. A severe nuclear accident occurs at Chernobyl in the former Soviet Union. 1769... 

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