Geological Disposal of High Level Nuclear Waste

1 Geological Disposal of High Level Nuclear Waste 

Spent fuel from nuclear power stations contains radiogenic U and Pu, and highly radioactive waste solution is produced when the spent fuel is reprocessed. This waste solution needs to be disposed of as it remains highly radioactive for a very long period. 

Groundwater penetrating a repository site will dissolve radioactive elements from the waste glass (Fig. 6.22). The radioactive elements may then be transported for an extended period and over a considerable distance from the repository site by the ground water flow. It is very important to predict both the migration rate, die flux of radioactive elements, and the temporal variation in radioactivity in the near-surface enviroiunent. 

In order to clarify this process, the chemical composition of the ground water in the buffer material (bentonite), corrosion mechanisms of the overpack, dissolution 

Degrading Waste Perforated canister L Fractured crystalline basement 

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Several types of nature-humans interactions with respect to materials and energy include resources, waste and global environmental problems (Fig. 6.1). In this Chapter we focus on the global environmental and waste problems such as acid rain, CO2 emission, underground CO2 sequestration, geological disposal of high level nuclear waste, and water and soil pollutions. 

Ringwood, A. E. 1985. Disposal of high level nuclear wastes A geological perspective. Mineralogical Magazine, 49, 159-176. 

Understanding the hydrogeological conditions for a future repository is crucial for safe disposal of high level nuclear waste. It is well known that only a part of geologically observable fractures are hydraulically conductive. Due to heterogeneity, the prediction of hydraulic conductivity of fractured media is a challenging task. 

PNC (Power Reactor and Nuclear Fuel Development Corporation) Research and development on geological disposal of high-level radioactive waste. First Progress Report, PNC TN 1410 93-059 (1992). 

RAMSPOTT, L.D., et al.. Impacts of new developments in partitioning and transmutation on the disposal of high-level nuclear waste in a mined geologic repository. Lawrence Livamore National Laboratory Report, UCRL ID-109203 (1992). 

Heimann, R.B. (1987) A statistical approach to evaluating durability of a simulated nuclear waste glass, in The Geological Disposal of High-Level Radioactive Wastes (ed. D.G. Brookins), Theophrastus Publ., S.A., Athens, Greece, pp. 181-205. 

NRC (1983). U.S. Nuclear Regulatory Commission. 10 CFR Part 60—Disposal of high-level radioactive wastes in geologic repositories, Final rule,... 

US Nuclear Regulatory Commission (2001) 10 CFR Parts 2, 19, 20, 21, etc. disposal of high-level radioactive wastes in a proposed geological repository at Yucca Mountain, Nevada final rule. Federal Register 66(213), 55732-55816. 

After the fuel is irradiated in the reactor, there are two divergent paths proposed to handle the used fuel. The first is to package it and dispose of it in a geologic repository as high-level nuclear waste. The alternative is to reprocess it to extract the remaining uranium and also recover the plutonium that was produced during irradiation. The waste from this process is the fission products. As seen in Chapter 14, there are several processes that can be used to preserve the useful uranium and plutonium. 

Yucca Mountain, Nevada, is being considered as the site for deep geological disposal of U.S. high-level nuclear wastes. Any release of uranium (or other radionuclides) from the waste to... 

Another benefit for the SFR fuel cycle system is the reduction of environmental burden by recycling all actinide nuclides and partitioning selected fission products (FPs). The spent fuel contains minor actinides (MAs ie, neptunium, americium, curium, etc.) as well as uranimn and plutonium. In the conventional nuclear fuel cycle, those MAs and FPs are disposed of in a deep geological repository as high-level radioactive wastes. Because of the long-lived radioactive MAs such as Am (half-life 433 years) and Np (half-life 2.1 million years), it takes several hundred thousand years to reduce the radiotoxicity of high-level radioactive waste to the level of natural uranium. 

Another focus of our current work concerns the applicability of international research to om inventory. There is a large amount of research taking place around the world the nuclear research community is a tmly global discipline. Many of these are studies that are directly relevant to a geological disposal facility and topics include, for example, the evolution of spent fuel subsequent to the eventual closure of the disposal facility, as well as the durabihty of high level vitrified wastes. 

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