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Finding ways to safely store and ultimately dispose of nuclear waste remains a matter of considerable debate. This volume describes the steps needed to design a new, single-purpose organization to manage and dispose of commercial and defense high-level radioactive materials and examines three models for such an organization—federal government corporation, federally chartered private corporation, and independent government agency.

This paper provides a comparative evaluation of the mechanical properties, corrosion resistance, and gamma-ray shielding performance of four different types of tungsten carbide (WC)-NiCr coatings deposited on cold-rolled steel surfaces, which are used as materials for low- and intermediate-level radioactive waste (LILW) storage containers. The four types of coatings were classified as WC-85, WC-73, WC-66, and WC-39 according to their WC content and were applied to the cold-rolled steel surfaces using the High-Velocity Oxygen Fuel (HVOF) spraying process. The performance of the layered coatings was analyzed in terms of their microstructure, hardness, wear resistance, adhesion strength, corrosion properties, and gamma-ray shielding characteristics. Coatings with elevated WC contents showed enhanced mechanical properties and gamma-ray shielding effectiveness, whereas coatings with relatively lower WC contents and higher NiCr contents exhibited greater corrosion resistance. This paper discusses the performance of WC-NiCr coatings from the viewpoint of enhancing the durability and safety of commercial LILW storage containers.

This research focused on developing a protective coating with improved radiation and corrosion resistance properties for nuclear waste disposal containers. The coating was developed by using radiation-resistant polymeric binder, ethylene propylene diene monomer as the base matrix, zinc oxide nanoparticles, and other reagents. Rheological parameters of coating formulations were analyzed to ensure that it could be applied by spray technique. Prepared coating formulations were applied on mild steel panels, and corrosion studies were performed in a salt spray chamber. To study the effect of gamma radiation on coating formulations, coated mild steel panels were irradiated at different radiation doses (up to 1800 kGy) using cobalt-60 as a radiation source. The dose and intensity of the radiation source were estimated based on the life of the waste package containing major radionuclide, such as Cs-137 and Sr-90, for simulating the disposal environment. The characterization of the coated panels was carried out before and after radiation exposure for dry film thickness, adhesion, and mechanical properties such as cross-cut adhesion, scratch hardness, pull off strength, tensile strength, and elongation. Thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy were also studied to see the effective changes in the coating after radiation exposure. The results showed that the high dose of radiation affecting the coating was in the marginal range, and it could withstand a radioactive as well as corrosive environment. The developed coating was found suitable to use for radioactive waste storage containers for long-term storage of low-level radiation waste.

The paper examines the coupled thermo-hydro-mechanical (THM) processes that develop in a fractured rock region within a fluid-saturated rock mass due to loads imposed by an advancing glacier. This scenario needs to be examined in order to assess the suitability of potential sites for the location of deep geologic repositories for the storage of high-level nuclear waste. The THM processes are examined using a computational multiphysics approach that takes into account thermo-poroelasticity of the intact geological formation and the presence of a system of sessile but hydraulically interacting fractures (fracture zones). The modelling considers coupled thermo-hydro-mechanical effects in both the intact rock and the fracture zones due to contact normal stresses and fluid pressure at the base of the advancing glacier. Computational modelling provides an assessment of the role of fractures in modifying the pore pressure generation within the entire rock mass.

The ecological effects of accidental or malicious radioactive contamination are insufficiently understood because of the hazards and difficulties associated with conducting studies in radioactively-polluted areas. Data sets from severely contaminated locations can therefore be small. Moreover, many potentially important factors, such as soil concentrations of toxic chemicals, pH, and temperature, can be correlated with radiation levels and with each other. In such situations, commonly-used statistical techniques like generalized linear models (GLMs) may not be able to provide useful information about how radiation and/or these other variables affect the outcome (e.g. abundance of the studied organisms). Ensemble machine learning methods such as random forests offer powerful alternatives. We propose that analysis of small radioecological data sets by GLMs and/or machine learning can be made more informative by using the following techniques: (1) adding synthetic noise variables to provide benchmarks for distinguishing the performances of valuable predictors from irrelevant ones; (2) adding noise directly to the predictors and/or to the outcome to test the robustness of analysis results against random data fluctuations; (3) adding artificial effects to selected predictors to test the sensitivity of the analysis methods in detecting predictor effects; (4) running a selected machine learning method multiple times (with different random-number seeds) to test the robustness of the detected \"signal\"; (5) using several machine learning methods to test the \"signal's\" sensitivity to differences in analysis techniques. Here, we applied these approaches to simulated data, and to two published examples of small radioecological data sets: (I) counts of fungal taxa in samples of soil contaminated by the Chernobyl nuclear power plan accident (Ukraine), and (II) bacterial abundance in soil samples under a ruptured nuclear waste storage tank (USA). We show that the proposed techniques were advantageous compared with the methodology used in the original publications where the data sets were presented. Specifically, our approach identified a negative effect of radioactive contamination in data set I, and suggested that in data set II stable chromium could have been a stronger limiting factor for bacterial abundance than the radionuclides 137Cs and 99Tc. This new information, which was extracted from these data sets using the proposed techniques, can potentially enhance the design of radioactive waste bioremediation.

Clay-salt slimes, production wastes from “Belaruskali” (A Belarusian factory, producing potash fertilizers), have been tested as a low-cost, eco-friendly potential sorbent for the removal of radionuclides from aqueous solutions, and may be a component of the cement filling of drums used in the storage of radioactive wastes. The efficiency of sorptive removal of caesium(I)-137, strontium(II)-90, europium(III)-152, and americium(III)-241 was examined with respect to the time of phase equilibration, pH, sorbent dosage, and the presence of salts and complexing agents. Irradiation stability of the material was also studied. It was found that uptake of the radionuclides is almost complete. A procedure for the removal of technetium-99 has been also proposed. Experimental results obtained within the presented work confirm our expectations.