Isolation, geologic

All the countries that produce nuclear waste have chosen the same alternative for the ultimate disposition of HLW, deep geological isolation, and they did so indepeiideiitly of one another. The United States has the most radioactive nuclear waste and the most complicated array of waste types of any nuclear country. Only in the United States can one find the same economy of scale for waste handling. Thus, it leads the world in most activities aimed at safe isolation. Ill France, Japan, and Great Britain, however, reprocessing is routinely practiced. Those countries reprocess HLW for many other countries. As mentioned above, reprocessing is not currently allowed in the United States. 

The objective of geologic isolation of radioactive wastes is to preclude their reaching the biosphere until after they have decayed to the extent that they no longer constitute a health hazard. Concern over radioactive wastes from military, industrial and research uses has elicited many lines of commentary and deep concern from many individuals. In California, the concern about waste disposal was the focal point in establishing a moratorium on the construction of new reactors until a satisfactory waste disposal technology could be demonstrated. 

Other options that have been considered for HLW include outer space ejection and burial in deep ocean trenches. The consensus worldwide is that deep geological isolation is the best option. The United States leads in studying a specific site, Yucca Mountain. In other countries, even those generating a larger percentage of their power with nuclear power, the small volumes awaiting burial allow them more time to choose a location. 

The action that could lead to such release is placement of the wastes in geologic formations. Such action is known, in waste management terminology, as geologic isolation since its objective is to isolate the wastes from the biosphere. 

There are four candidate geologic isolation environments the sea floor, ice sheets, deep continental geologic formations, and shallow continental geologic formations. In waste manage-... 

For purposes of assessing the safety of repositories of radioactive wastes placed in geologic isolation, actinide behavior in the environment has been interpreted in terms of five steps of prediction ... 

The ingestion toxicity indices of the actinides in the wastes are shown as a function of decay time in Fig. 8.9 [P2]. Because the actinides are nonvolatile and because the wastes are expected to be geologically isolated, ingestion toxicity is probably a more important measure than inhalation toxicity. During the first 600 years the total toxicity index is controlled by the fission products, mainly Sr. It is thereafter controlled by Am and Am, followed by... 

The hydrolytic chemistry of Pu is important in that it affects the behavior and mobility of plutonium in the environment [A2] and in geologically isolated radioactive wastes that may be subjected to slow leaching by ground water. The absorption spectra of the Pu(TV) polymer is similar to that of the plutonium hydroxide precipitate Pu(0H)4 [L4]. Experimental data in Fig. 

Kiihn, K., and J. Hamstra Geologic Isolation of Radioactive Wastes in the Federal Republic of Germany and the Respective Program of the Netherlands, Proceedings of the International Symposium on the Management of Wastes from the LWR Fuel Cycle, Denver, 1976, Report CONF-76-0701, p. 580. 

Board on Radioactive Waste Management, National Research Council (1999). Discussion Papers prepared for the Workshop on Disposition of High-Level Radioactive Waste Through Geological Isolation, National Academy Press, Washington, DC. 

If the strategy of deep geological isolation of the irradiated fuel without its reprocessing is chosen then it can result in certain delay in fast reactor construction. 

HLW generally refers to materials requiring permanent isolation from the environment. It frequently arises as a by-product of nuclear power generation (reprocessing streams or spent fuel) or from the isolation of fissile radionuclides from irradiated materials to be used in nuclear weapons production. When nuclear fuel from reactor operations (civilian or defense) is chemically processed, the radioactive wastes include highly concentrated liquid solutions of nuclear fission products. Typically, these waste streams are solidified either in a glass (vitrification) or in another matrix. Both the liquid solutions and the vitrified solids are considered HLW. If the nuclear fuel is not processed, it too, is considered as HLW and must be dispositioned. The path most often proposed is direct, deep geologic isolation. 

Commission of European Community, Performance Assessment of Geological Isolation Systems for Radioactive Wastes, (EWU 11777) (1988). 

Other options that have been considered for HLW include outer space ejection and burial in deep ocean trenches. The consensus worldwide is that deep geological isolation is the best option. 

The change in the concentration of radioactive elements over time in far-field environments can be expressed as follows (Performance Assessment of Geological Isolation Systems (PAGIS) 1984) ... 

National Research Council. 1999. Disposition of high-level radioactive waste through geological isolation Development, current status, and technical and policy challenges. Natl. Academy Press, Washington, DC. ... 

Consumption of transuranics in a closed fuel cycle, thus reducing the radiotoxidty and heat load, which facilitates waste disposal and geologic isolation and... 

D Alessandro, M. Gera, F. 1986. Geological isolation of radioactive waste in clay formations fractures and faults as possible pathways for radionuclide migration. Radioactive Waste Management and the Nuclear Fuel Cycle, 7(4), 381-406. 

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