Repositories

This does not have to be so Why not build an uninterrupted stream of information from the producer (the bench chemist) to the consumer (the reader of a journal or book, or the scientist that puts a query into a database) It is quite clear that the producers of information knows best what experiments were done, what observations were made, what results have been obtained. They should put this information into electronic laboratory books, augmented with spectral data (that they can obtain directly from the analytical laboratory). From this electronic repository aU other information sources -manuscripts, journals, books, databases - could be filled, clearly sometimes by manual selection, but not by changing data ... 

The value of the torsional energy increment has been variously estimated, but TORS = 0.42 kcal mol was settled on for the bond contribution method in MM3, In the full statistical method (see below), low-frequency torsional motion should be calculated along with all the others so the empirical TORS inererneut should be zero. In fact, TORS is not zero (Allinger, 1996). It appears that the TORS inererneut is a repository for an energy eiror or errors in the method that are as yet unknown. 

Protein Data Bank (Section 27 20) A central repository in which crystallographic coordinates for biological mole cules especially proteins are stored The data are accessi ble via the Worldwide Web and can be transformed into three dimensional images with appropriate molecular modeling software... 

Complex environmental samples originate from diverse matrices (the predominant material of which the sample to be analyzed is composed). These matrices, usually either water or soil/sediment, can contain as many as 50 to 100 organic components at widely varying concentrations. The EPA approach to the analysis of these samples involves the analysis of specific (or target) compounds and the use of authentic standards for quality control. The current number of standards in the EPA repository is about 1500, and their analysis is covered by various approved methods. 

Spent nuclear fuel has fission products, uranium, and transuranic elements. Plans call for permanent disposal in underground repositories. Geological studies are in progress at the Yucca Mountain site in Nevada. Until a repository is completed, spent fuel must be stored in water pools or in dry storage casks at nuclear plant sites. 

The throwaway fuel cycle does not recover the energy values present ia the irradiated fuel. Instead, all of the long-Hved actinides are routed to the final waste repository along with the fission products. Whether or not this is a desirable alternative is determined largely by the scope of the evaluation study. For instance, when only the value of the recovered yellow cake and SWU equivalents are considered, the world market values for these commodities do not fully cover the cost of reprocessing (2). However, when costs attributable to the disposal of large quantities of actinides are considered, the classical fuel cycle has been the choice of virtually all countries except the United States. 

Regulations include guidelines on geologic conditions. Of special interest is the stabiUty of the geology against faulting, volcanic action, and earthquakes. The repository is to be located in an arid region, where the water table is quite low. The host rock is to have a suitable porosity and a low hydrauhc conductivity. 

Tuff, a compressed volcanic material, is the primary constituent of Yucca Mountain, near Las Vegas, Nevada, the site selected by Congress in 1987 for assessment for spent fuel disposal. An underground laboratory, to consist of many kilometers of tunnels and test rooms, is to be cut into the mountain with special boring equipment to determine if the site is suitable for a repository. 

Site characterization studies include a surface-based testing program, potential environmental impact, and societal aspects of the repository. Performance assessment considers both the engineered barriers and the geologic environment. Among features being studied are the normal water flow, some release of carbon-14, and abnormal events such as volcanic activity and human intmsion. The expected date for operation of the repository is 2013. 

Transuranic Waste. Transuranic wastes (TRU) contain significant amounts (>3,700 Bq/g (100 nCi/g)) of plutonium. These wastes have accumulated from nuclear weapons production at sites such as Rocky Flats, Colorado. Experimental test of TRU disposal is planned for the Waste Isolation Pilot Plant (WIPP) site near Carlsbad, New Mexico. The geologic medium is rock salt, which has the abiUty to flow under pressure around waste containers, thus sealing them from water. Studies center on the stabiUty of stmctures and effects of small amounts of water within the repository. 

Other fuel besides that from U.S. commercial reactors may be disposed of in the ultimate repository. PossibiUties are spent fuel from defense reactors and fuel from research reactors outside of the United States. To reduce the proliferation of nuclear weapons, the United States has urged that research reactors reduce fuel enrichment in uranium-235 from around 90 to 20%. The latter fuel could not be used in a weapon. The United States has agreed to accept spent fuel from these reactors. 

The primary issue is to prevent groundwater from becoming radioactively contaminated. Thus, the property of concern of the long-lived radioactive species is their solubility in water. The long-lived actinides such as plutonium are metallic and insoluble even if water were to penetrate into the repository. Certain fission-product isotopes such as iodine-129 and technicium-99 are soluble, however, and therefore represent the principal although very low level hazard. Studies of Yucca Mountain, Nevada, tentatively chosen as the site for the spent fuel and high level waste repository, are underway (44). 

If the economics of recycling were improved, that option would become preferable for spent fuel because the permanent repository issues of the residual fission products would be simpler. The economic value of the energy generated from the recycled plutonium and uranium would substantially allay the costs of the repository as compared to the spent fuel throwaway option. 

Miscellaneous. Iridium dioxide, like RUO2, is useful as an electrode material for dimensionally stable anodes (DSA) (189). SoHd-state pH sensors employing Ir02 electrode material are considered promising for measuring pH of geochemical fluids in nuclear waste repository sites (190). Thin films (qv) ofIr02 ate stable electrochromic materials (191). 

To recovery and recycle or vitrification and disposal in deep geologic repository... 

Repository, including a hard copy reference hbraiy and collection center and an on-hne information retrieval and ordering system. 

Contaminant transfer to bed sediments represents another significant transfer mechanism, especially in cases where contaminants are in the form of suspended solids or are dissolved hydrophobic substances that can become adsorbed by organic matter in bed sediments. For the purposes of this chapter, sediments and water are considered part of a single system because of their complex interassociation. Surface water-bed sediment transfer is reversible bed sediments often act as temporary repositories for contaminants and gradually rerelease contaminants to surface waters. Sorbed or settled contaminants are frequently transported with bed sediment migration or flow. Transfer of sorbed contaminants to bottomdwelling, edible biota represents a fate pathway potentially resulting in human exposure. Where this transfer mechanism appears likely, the biotic fate of contaminants should be assessed. 

This chapter has only scratched the surface of the multitude of databases and data reviews that are now available. For instance, more than 100 materials databases of many kinds are listed by Wawrousek et al. (1989), in an article published by one of the major repositories of such databases. More and more of them are accessible via the internet. The most comprehensive recent overview of Electronic access to factual materials information the state of the art is by Westbrook et al. (1995), This highly informative essay includes a taxonomy of materials information , focusing on the many different property considerations and property types which an investigator can be concerned with. Special attention is paid to mechanical properties. The authors focus also on the quality and relutbility of data, quality of source, reproducibility, evaluation status, etc., all come into this, and alarmingly. 

Aerometric Information Retrieval System (AIRS) a eomputer-based repository of U.S. air pollution information administered by the EPA Offiee of Air Quality Planning and Standards. 

It has been traditional to subject workers to higher risks than the public, (a) Write a short discussion of the equities of this practice with consideration for the fact the worker may leave employment that imposed a long term risk, (b) The Nevada Test Site has been selected as a possible location for a high level waste repository. For purposes of the risk assessment, the workers in the repository will be treated as workers with subsequent higher allowable risk. There are many other workers at NTS. Discuss whether these should be treated as workers or public, (c) If they are treated... 

Data base A repository for equipment reliability information categorized to facilitate data retrieval or tabular lists of multiple data vectors, with little text except that needed to explain the data presentation format. 

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