Fossils, radioactive

The use of nuclear power has been a topic of debate for many years. Nuclear fuel represents a resource for generating energy weU into the future, whereas economically recoverable fossil fuel reserves may become depleted. Worker exposure, injuries, and fataHties in nuclear fuel mining are reportedly far less compared to those associated with recovery and handling of fossil fuels. Potential hazards associated with transporting and storing radioactive wastes do exist, however. 

Finally, one might note that there are concerns over problems of radioactive wastes tens of thousands of years in the future. Should there not be even more concern over the lack of needed fossil fuel supplies only a hundred or two hundred years from now. Fossil fuels are vitally needed for special energy tasks and particularly, for special non energy uses such as chemical and manufacturing production... 

The best sealed-in minerals are zircons, zirconium silicate minerals which are formed when melted lava on the flanks of volcanoes solidifies. When the zircons crystallize out, they incorporate radioactive uranium (in particular 238U), which decays in several steps, leading Anally to the lead isotope 208Pb. The rate of decay is very low, as the half-life of uranium-238 is 4.5 x 109 years. Thus, the U-Pb-zircon method for age determination of Precambrian rock is very important. The fossils studied by Schopf were sandwiched between two lava layers (Schopf, 1999). The volcanic layers were dated to 3.458 0.0019 x 109 years and 3.471 0.005 x 109 years the age of the fossil layer (Apex chert) was thus determined to be about 3.465xlO9 years. 

Nuclear fission power plants were at one time thought to be the answer to diminishing fossil fuels. Although the enriched uranium fuel was also limited, an advanced nuclear reactor called breeders would be able to produce more radioactive fuel, in the form of plutonium, than consumed. This would make plutonium fuel renewable. Although plutonium has been called one of the most toxic elements known, it is similar to other radioactive materials and requires careful handling since it can remain radioactive for thousands of years. 

Conventional nuclear reactors and advanced breeder reactors were America s primary energy strategy since the 1950s to resolve the fossil fuel problem but when a reactor accident occurred in 1979 at Three Mile Island in Pennsylvania, public and investor confidence in nuclear fission dropped. The accident was triggered by the failure of a feedwater pump that supplied water to the steam generators. The backup feedwater pumps were not connected to the system as required, which caused the reactor to heat up. The safety valve then failed to act which allowed a radioactive water and gas leak. This was the worst nuclear power accident in the U.S., but in this accident no one was killed and no one was directly injured. At Three Mile Island faulty instrumentation gave incorrect readings for the... 

Fossil fuel electrical power plants can be more hazardous to humans than nuclear power plants because of the pollutants. A 1,000 megawatt (MW) coal-fired power plant releases about 100 times as much radioactivity into the environment as a comparable nuclear plant. A 1,000-MW power plant will use 2,000 railroad cars of coal or 10 supertankers of oil but only 12 cubic meters of natural uranium every year. Fossil fuel... 

Radioactivity, radioactive elements and nuclear reactors are found in nature. There are at least 14 natural fission reactors in the Oklo-Okelobon-do natural uranium formation in Gabon on the west coast of Africa. These fossil reactors had sufficient amounts of U-235 to allow chain reactions to... 

The present world energy supply system is facing three basic problems (1) limitation of fossil fuel resources, (2) climate change by carbon dioxide emission, and (3) insecurity by nuclear weapon competence and radioactive materials. The strategic goal therefore should be to transition to unlimited resources, use zero-emission fuels and accept no options for abuse. 

Potential applications for CA-CDI technology include the purification of boiler water for fossil and nuclear power plants, volume reduction of liquid radioactive waste, treatment of agricultural wastewater containing pesticides and other toxic compounds, creation of ultrapure water for semiconductor processing, treatment of wastewater from electroplating operations, desalination of seawater, and removal of salt from water for agricultural irrigation. 

In short, with sublime irony, Duchamp has employed a modernist visual vocabularly to camouflage an underlying, deliciously anachronistic, allegorical content. Hence, his playful physics is neo-Alchemy, a strictly contemporary, modernist solution. Like some contemporary writers, Duchamp validates the heavily pictorialized fossil science by inserting it into the modernist, pseudoscientific context of radioactivity, electricity, automobiles, X rays, and nuclear physics. According to Duchamp s later recollection to Tomkins,... 

Radioactive elements are ones in which the atoms break up, changing into atoms of other elements. The time taken for half the original element to disappear is called the half-life. The man-made element fermium has a half-life of 80 days. Thus, if a gramme of fermium were made today, less than one-sixteenth of a gramme would be left at the end of a year. The half-life can be very useful. By measuring the amount of radioactive carbon left in fossil remains, or other matter that was once alive, scientists can determine their age. 

The enormous importance of carbon in such diverse fields as inorganic and organic chemistry and biology is well known however, only the aspects of carbon relevant to catalysis will be described here. The main topics we are concerned with are porous activated carbons, carbon black as catalyst supports and forms of coking. Carbon is also currently used as storage for natural gas and to clean up radioactive contamination. Carbon is available at low cost and a vast literature exists on its uses. Coal-derived carbon is made from biomass, wood or fossil plants and its microstructure differs from carbon made from industrial coke. Activated carbons are synthesized by thermal activation or by chemical activation to provide desirable properties like high surface area. 

The geologic timescale for the Earth is based mostly on stratigraphy (the depositional succession of layers from bottom to top). Most strata are sedimentary rocks. The relative ages of the sedimentary layers are determined by the sequence of deposition and by the fossils that they contain. It is not possible to use radioactive isotopes to measure the time that a sediment was deposited, because deposition does not reset radiometric clocks. However, the absolute ages of sediment layers and the fossils they contain have been determined by measuring radiometric ages of volcanic ash layers in the sequence or lavas that crosscut sedimentary strata. 

The benefits of fission power are plentiful electricity, conservation of many billions of tons of fossil fuels annually, and the elimination of the megatons of sulfur oxides and other poisons put into the air each year by the burning of fossil fuels. The drawbacks are the formation of massive quantities of radioactive wastes that require long-term safe storage. 

Worldwide, the amount of energy available from coal is estimated to be about ten times greater than the amount available from all petroleum and natural gas reserves combined. Coal is also the filthiest fossil fuel because it contains large amounts of such impurities as sulfur, toxic heavy metals, and radioactive isotopes. Burning coal is therefore one of the quickest ways to introduce a variety of pollutants into the air. More than half of the sulfur dioxide and about 30 percent of the nitrogen oxides released into the atmosphere by humans come from the combustion of coal. As with other fossil fuels, the combustion of coal also produces large amounts of carbon dioxide. 

I he fossil fuels currently available to us are limited. At present rates of con-X sumption, known recoverable oil and gas reserves will disappear by the end of the century and coal reserves several centuries after that. Furthermore, burning fossil fuels adds undesirable amounts of greenhouse gases to the atmosphere. Nuclear fission reactors do not emit greenhouse gases, but they generate massive quantities of radioactive wastes. Nuclear fusion reactors offer many potential benefits, but it may take many decades before they are both technologically and economically feasible. So what do we do ... 

The steam from a BWR is, of course, radioactive. The radioactivity is primarily 16N, a very short-lived nitrogen isotope (7 seconds half-life) so that the radioactivity of the steam system exists only during power generation. Extensive generating experience has demonstrated that shutdown maintenance on a BWR turbine, condensate, and feedwater components can be performed essentially as a fossil-fuel plant. 

Eisenbud M, Petrow HG. 1964. Radioactivity in the atmospheric effluents of power plants that use fossil fuels. Science 144 288-289. 

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