Phytoremediation of radioactive waste is a process that uses plants to remove, transfer, or immobilize radionuclides from the contaminated soil, sediment, sludge, or water, and it is a useful method for treating large-scale low-level radionuclide contamination. However, there have not been established criteria which can be utilized to screen out suitable plant species that are capable of remedi...

The objective of this research is to develop a fundamental understanding of the physico-chemical mechanisms that cause foaminess in the DOE High Level (HLW) and Low Activity radioactive waste separation processes and to develop and test advanced antifoam/defoaming agents. Antifoams developed for this research will be tested using simulated defense HLW radioactive wastes obtained from the Hanfor...

Following the ban on deep sea disposal of radioactive wastes in 1983 the Atomic Weapons Establishment (AWE) in the United Kingdom (UK) has stored plutonium (Pu) and uranium (U) contaminated wastes on site in 200 l steel drums or as wrapped packages containing filters or other materials. This was because of difficulty in demonstrating compliance with the with the 100 Bq/g Pu alpha activity limit...

Highly compacted sand-bentonite mixtures are often considered as possible engineered barriers in deep high-level radioactive waste disposals. In-situ, the saturation of these barriers from their initially unsaturated state is a complex hydro-mechanical coupled process in which temperature effects also play a role. The key parameter of this process is the unsaturated hydraulic conductivity of th...

Geological storage is an important concept for high-level radioactive waste (HLW) disposal, and detailed studies are required to protect the environment from contamination by radionuclides. This paper presents a series of geomechanical studies on the site selection for HLW disposal in the Alxa area of China. Surface investigation in the field and RQD analyses on the drill cores are carried out ...

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Models that calculate the probability that a new volcano or a dike from a nearby eruption will intersect the footprint of the proposed high-level nuclear waste repository are generalized based on a conceptual model developed for the space transportation industry. The proposed hazard area, defined such that every new eruption that occurs there will disrupt the repository, plays a fundamental rol...

In recent years, geological disposal of radioactive waste has focused on placement of highand intermediate-level wastes in mined underground caverns at depths of 500–800 m. Notwithstanding the billions of dollars spent to date on this approach, the difficulty of finding suitable sites and demonstrating to the public and regulators that a robust safety case can be developed has frustrated attemp...

A model for single-phase flow in porous media that are hierarchically fissured in regular patterns was derived by a recursive asymptotic expansion technique in [16] and part of [24]. This work rigorously justifies that model. Through recursive homogenization, we extend the doubleporosity model in [5], which has one fracture system and a matrix (rock) block system, to a triple-porosity model tha...

This review provides a comprehensive evaluation of the state-of-knowledge of radiation effects in crystalline ceramics that may be used for the immobilization of high-level nuclear waste and plutonium. The current understanding of radiation damage processes, defect generation, microstructure development, theoretical methods, and experimental methods are reviewed. Fundamental scientific and tech...