Carbonation is a naturally-occurring process whereby Ca-containing cement phases lose their hydration water and are converted to carbonate minerals by reaction with atmospheric CO&#8322;. As these secondary minerals develop in the microstructure of hydrated cement, porosity, pore-size distribution and permeability are decreased. These are all considered desirable properties in a wasteform. The objective of this study was to examine the effect of carbonation and different pozzolans on the leach performance and mechanical strength of ordinary Portland cement (OPC) wasteforms. Two methods of accelerated cement carbonation were used: <ol> <li>A vacuum carbonation method, where wasteforms are placed in an evacuated, sealed cell and subjected to small additions of CO&#8322; over several days at near vacuum conditions; and <li>A one-step carbonation method, where CO&#8322; gas is added to the wasteform paste as it is being mixed. </ol> Thirteen elemental constituents of interest to the safety assessments of long-term management of Ontario Power Generation's radioactive waste (Cl, N, S, Se, 13C, Th, Pb, Co, Ni, Cu, Sr, Ba and Cs) were stabilised/solidified via cement mix water. Wasteforms were produced with only OPC, OPC and fly ash, or OPC and silica fume. Most wasteforms were carbonated using one of the carbonation methods. Some wasteforms were not carbonated and served as controls. Wasteforms were subjected to either standard leach tests or compressive strength tests. The extent of carbonation was found to be about 20% for vacuum carbonation method, substantially higher than that for one-step treatment (up to about 10%). For vacuum carbonated wasteforms, carbonation occurred at the outer selvages of the wasteforms, whereas one-step treatment resulted in homogenous carbonation. Generally, compared to uncarbonated OPC wasteforms, vacuum carbonation increased leaching of elements that are anionic in cementitious conditions (Cl, N, S, Se, 13C, Th), decreased leaching of large metal cations (Sr, Ba, Cs, Pb) and had negligible effect on the leaching of the elements that form hydroxyl complexes (Co, Ni, Cu). 13C was the only anionic element whose leachability was reduced by vacuum carbonation, as it may be precipitated in the form CO32- in the large quantity of secondary carbonate minerals produced during the vacuum carbonation process. One-step carbonation did not result in substantial reductions in leachability, compared to uncarbonated OPC wasteforms. However, it had an interesting inverse effect on large metal cation leachability from fly ash- and silica fume-containing wasteforms. A model is presented that proposes that porewater pH changes can have an effect on waste element leachability because 1) the C-S-H Ca/Si ratio is dependent on the equilibrating porewater pH and 2) the degree of ion sorption on C-S-H is dependent on the C-S-H Ca/Si ratio. This model should be tested experimentally as it has important implications on wasteform design. Because of this inverse behaviour, overall neither pozzolan outperformed the other with respect to leachability. Generally, for uncarbonated wasteforms, OPC retained the elements more effectively than OPC with pozzolans. For pozzolans, the leachability of these elements from OPC with fly ash was lower than that of OPC with silica fume. Leaching of Cs was anomalously low from uncarbonated OPC wasteforms, but follow-up experimentation did not corroborate this anomaly. Further testing of these wasteforms to determine how the mineralogical fate of Cs can differ between wasteforms is recommended. All wasteforms tested were of acceptable strength (<0. 689 MPa). Fly ash, and, to a greater degree, silica fume, improved wasteform strength when compared to OPC wasteforms. Carbonation treatments had little effect on wasteform strength. This study has provided much information about the leaching characteristics of a representative set of waste elements from several cement-based wasteform treatments. Although it has not indicated a wasteform design that is ideal for all elements studied, it does suggest that some treatments may be effective for certain groups of elements. Most notably, vacuum carbonation shows promise in improving the immobilisation of isotopes of large metal cations such as Sr, Ba, Cs and Pb as well as 14C (as suggested by 13C here) in cement-based wasteforms.

Title from PDF of title page. / Document formatted into pages; contains 152 pages. / Thesis (M.S.C.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / Monson ABSTRACT The U.S. Department of Energy (DOE) has been engaged in a viability study for a potential underground geological repository in Yucca Mountain, Nevada. The repository is being designed for disposal of high level nuclear waste. A reference design for the repository has focused on the use of natural and manmade barriers to assure that radionucleide release will not be significant though an extended time period on the order of 10,000 years. The reference design utilizes manmade metallic components that are expected to last for this time period. / The specified metallic materials depend on a phenomenon known as metallic passivity to achieve their expected service lives. It is difficult to demonstrate this type of service life for these metallic materials as they have only been in commercial use for less than 100 years. There have been metal artifacts and metallic materials that have survived for long time periods, however, little is known about whether these artifacts have been exposed to conditions where they have been immune to corrosion, exhibiting passive behavior, or actively corroding at an extremely low rate. A demonstration of metallic passive behavior being maintained over many thousands of years would greatly increase confidence in the expectation that passive behavior could be maintained on the repository waste package / A demonstration of metallic passive behavior being maintained over many thousands of years would greatly increase confidence in the expectation that passive behavior could be maintained on the repository waste package materials. Long-lived metallic materials, such as iron, copper, nickel, and alloys based on these metals are materials that demonstrate passive behavior and have been identified in the literature as possible analogues, potentially useful to provide additional confidence in making projections of such long-term passive behavior.1, 4, 28, 45 This paper presents a study into some aspects of the corrosion behavior of Josephinite. / Josephinite is a naturally occurring assemblage of a metallic alloy of nickel and iron in conjunction with a host rock. The typical metallic composition is approximately 70% nickel and 30% iron. The material has been reported in association with geologic features with age into the millions of years. The study used corrosion measurement techniques to assess the behavior of the mineral immersed in aqueous solutions of various pH. Corrosion measurement techniques utilized included potentiodynamic polarization, open circuit corrosion potential, and electrochemical impedance spectroscopy. / Other techniques utilized in the study included visual and metallographic examinations with both optical and scanning electron microscopy. Test results from this study indicate that passive behavior characterizes Josephinite specimens immersed in naturally aerated buffered aqueous solutions in a range of pH from 6 to 9. This range has been reported for the geographic area where Josephinite materials are found in southwest Oregon. This suggests that passive behavior may be responsible for the material longevity as opposed to the material being immune or undergoing slow but active corrosion. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Nuclear waste remains radioactive for thousands of years. Burying it underground in an enormous repository, called Onkalo, surrounded and secured by solid rock is the long-term solution Finnish authorities implement right now. Once the repository is filled up, it will be locked up forever and never opened again. At the same time three new nuclear power plants are built. Out of Sight, out of Mind? Ultimately, this raises questions: Can this be the solution for final disposal of nuclear waste? How do we understand a problem clearly exceeding our capabilities as human beings? How do we deal with the dilemmas of uncertainty, invisibility, time, demand, possible contamination, and our individual responsibility as human beings? Understanding Through Interaction I designed three everyday products, a lamp, a toy for children, and a pregnancy test, that afford a familiar everyday action on one hand, while exposing a dilemma related to Onkalo on the other. In doing so, the artifacts make those dilemma tangible and facilitate understanding and critical thinking. Sharing a personal experience, the users can engage in a personal discourse around nuclear waste actively, opposing the distant and highly politicalised discourse spread by the media.

This report outlines the legal requirements for consulting with American Indian groups and identifying their traditional cultural values that could be impacted during site characterization activities associated with the high level nuclear waste disposal facility project at Yucca Mountain, Nevada. More specifically the report discusses culturally relevant methods for (a) identifying persons knowledgeable about traditional cultural resources associated with properties or sites where project site characterization activities may occur and that have value to contemporary American Indian groups, and (b) implementing consultation procedures with concerned Indian peoples as required by federal policy. The report is divided into three chapters. Chapter One discusses the two federal policies most relevant to the identification of American Indian traditional cultural values and specifies which American Indian groups should be consulted during site characterization. Chapter Two provides a Native American perspective on traditional cultural values and identifies the types of values that are most likely to be of concern to Indian people and be located in the Yucca Mountain study area. Chapter Three presents a plan for identifying traditional cultural values and for consulting with the relevant Indian groups.

Nuclear power waste contains radioactive isotopes with long half lives and the problem lies in the fact that the lanthanides and actinides must be separated before the nuclear waste can be reprocessed. Transuranic Extraction (TRUEX), a liquid-liquid extraction method, has been developed but fails to separate the lanthanide and actinides and creates large volumes of liquid waste. It has been shown that attaching three CMPO (carbamoyl phosphine oxide) ligands used in the TRUEX process to a calixarene increases the separation and extraction efficiency of the system. The research goal is to attach the CMPO ligand to a polymer to make a membrane to be used in nuclear waste remediation. The triblock polymer system has been designed to have a cross-linking group to create the membrane structure, a solubilizing group to improve the flow of aqueous media through the membrane, and the CMPO ligand to chelate actinides. This paper describes the design of the polymer, its synthesis, and my research data. / text

The local information provided by nuclear magnetic resonance (NMR) makes it an ideal method for the structural investigations of materials lacking extended long-range ordering. This work focuses on investigations of two types of materials possessing very different types of disorder. The first section involves investigations of alkali borate glasses and the application of solid-state NMR techniques to probe short- and medium-range ordering in such glasses. Differences between the various alkali borates over a wide compositional range are probed using one and two-dimensional techniques. The use of double-resonance dipolar recoupling techniques to investigate cesium-boron distances is investigated. The second section probes a series of transition-metal cyanide coordination polymers. The bidentate nature of the cyanide ligand allows for the possibility of forming numerous isomers. Information about the isomer(s) present is gained via the various NMR parameters available, such as the chemical shifts, shift anisotropies and J-couplings. This is then extended to the characterization of paramagnetic transition-metal cyanides, where strong electron-nuclear interactions are shown to significantly increase spin-lattice relaxation rates allowing the acquisition of spectra without the need of typically employed enhancement techniques, yet often yielding spectra of better quality. Variable-temperature experiments allow a measure of the electron-nuclear interaction, which can be related to spatial proximity, and provide “diamagnetic” chemical shifts allowing comparison with other cyanides. J-couplings and chemical shift anisotropies are shown to be applicable in much the same fashion as with diamagnetic systems.

The local information provided by nuclear magnetic resonance (NMR) makes it an ideal method for the structural investigations of materials lacking extended long-range ordering. This work focuses on investigations of two types of materials possessing very different types of disorder. The first section involves investigations of alkali borate glasses and the application of solid-state NMR techniques to probe short- and medium-range ordering in such glasses. Differences between the various alkali borates over a wide compositional range are probed using one and two-dimensional techniques. The use of double-resonance dipolar recoupling techniques to investigate cesium-boron distances is investigated. The second section probes a series of transition-metal cyanide coordination polymers. The bidentate nature of the cyanide ligand allows for the possibility of forming numerous isomers. Information about the isomer(s) present is gained via the various NMR parameters available, such as the chemical shifts, shift anisotropies and J-couplings. This is then extended to the characterization of paramagnetic transition-metal cyanides, where strong electron-nuclear interactions are shown to significantly increase spin-lattice relaxation rates allowing the acquisition of spectra without the need of typically employed enhancement techniques, yet often yielding spectra of better quality. Variable-temperature experiments allow a measure of the electron-nuclear interaction, which can be related to spatial proximity, and provide “diamagnetic” chemical shifts allowing comparison with other cyanides. J-couplings and chemical shift anisotropies are shown to be applicable in much the same fashion as with diamagnetic systems.

Thorium(IV) and uranium(IV) coordination complexes have been studied for the last 60 years. They have shown interesting reactivity that is often divergent from that of transition metal complexes, and that also provides an insight into some unanticipated differences between thorium(IV) and uranium(IV). An introduction to thorium(IV) and uranium(IV) organometallic chemistry supported by carbocyclic and N-donor ligands is given in Chapter One. The reactivity of actinide alkyl, amide and alkynyl complexes towards small molecules is discussed and select examples provided. The redox chemistry of thorium and uranium is also introduced. Chapter Two describes the alkylation and amination chemistry of uranium(IV) and thorium(IV) trans-calix[2]benzene[2]pyrrolide ((L)2-) complexes, [(L)AnCl2], yielding new actinide(IV) complexes of the type [M(L-2H)An(R)] (M = Li or K, R = Me, CH2SiMe3, CH2Ph, N(SiMe3)2), where (L)2- undergoes further deprotonation to (L-2H)4-. Additionally, the lability of the [M(L-2H)An(R)] “ate”-complexes towards M+ ion exchange is addressed. Further, the selective ligand reprotonation of (L-2H)4- to (L)2- using HSiR'3 (R' = Me, iPr) and [Et3NH][BPh4] yielding [(L)An(C≡CSiR'3)2] and [(L)An(R)][BPh4] respectively, is explained. The reactivity of these complexes towards amines, silanes, alkenes, tin hydrides, silicone grease, tBuNC, H2, CO, CO2 or CS2 is described. Crystallographic characterisation shows that [(L)Th(N(SiMe3)2)][BPh4] contains an unusual example of a thorium(IV) bis-arene coordination mode. The reactivity of [(L)Th(C≡CSiMe3)2] towards a number of substrates including alkenes, [Ni(COD)2], [Pt(norbornene)3], P4, CO2 or H2 is also discussed. Activation of CO2 by [(L)Th(C≡CSiMe3)2] at 80 °C results in (L)2- functionalisation and abstraction to yield a new tricyclic organic molecule with the general formula LCO. The addition of [Ni(COD)2] to [(L)Th(C≡CSiMe3)2] and PR''3 (R'' = phenyl, cyclohexyl) yields heterobimetallic complexes [(L)Th(C≡CSiMe3)2·Ni(PR''3)]; these products display both dipyrrolic and bis-arene coordination. The changes in ligand coordination mode are discussed alongside DFT computational analyses that have been carried out by collaborators. The substitution reactions of [(L)AnCl2] with NaBH4 to form actinide(IV) borohydride complexes [(L)An(BH4)2] and subsequent attempted abstractions of BH3 from [(L)Th(BH4)2] are presented. Conclusions are provided at the end of the chapter. Chapter Three focusses on the oxidation chemistry of uranium(IV) within the (L)2- and (L-2H)4- ligand framework, prompted by the isolation of a uranium(V) complex [Li[(L)UO2]·LiI] from the oxidation of the uranium(IV) complex [Li(L-2H)U(Me)]. Conclusions are provided at the end of the chapter. Experimental methods and characterising data are given in Chapter Four.

New Czech nuclear law Abstract The topic of this diploma thesis is the new Czech nuclear law, i.e. the Czech nuclear law after the adoption of the new regulation. Nuclear law can be characterized as a set of legal norms containing the regulation of the peaceful use of nuclear energy and ionizing radiation. Their aim is to ensure the protection of health, life, property and the environment and to prevent the misuse of nuclear energy and ionizing radiation for non-peaceful purposes. The first chapter contains a brief insight first into the world's history, then in the history related to Czech Republic. Apart from history, this chapter also includes the current state and the near future of this area. The second chapter deals with the transnational significance of nuclear law, international and Union atomic law and the most important international organizations active in this field. The third chapter deals again with Czech atomic law, including its constitutional foundations, recent changes and comparison with the old legal regulations and its relationship with selected laws. On the State Administration Bodies and their role and powers are dealt with in chapter four. The fifth chapter analyzes sources of ionizing radiation, deals with their classification and the protection of human health and the environment...

Le travail présenté dans cette thèse s'inscrit dans la problématique générale du stockage souterrain des déchets radioactifs Nous nous intéressons au problème du drainage hyperlent qui est lié à la production de gaz, de l'hydrogène principalement, au sein du site de stockage. Bien que très faible en flux, d'où le caractère hyperlent du drainage, cette production représente des quantités significatives de gaz étant donné qu'elle s'opère sur des milliers d'année. L'étude est effectuée dans le cadre de la théorie de la percolation d'invasion en gradient. Nous montrons tout d'abord que ce processus de drainage est modélisable avec le modèle diphasique classique basé sur les lois de Darcy généralisées. Une étape essentielle concerne alors la spécification des paramètres de ce modèle. Nous montrons comment ils doivent être spécifiés en s'appuyant sur les comportements asymptotiques prévus par la théorie de la percolation pour un milieu infini. La solution obtenue indique que le drainage hyperlent fonctionne au voisinage de la pression de percée, qui fait l'objet d'une étude particulière, et est caractérisé par une faible désaturation du milieu et une grande sensibilité à la spécification des paramètres du modèle dans la gamme des très fortes saturations en fluide mouillant. Dans une deuxième partie nous étudions l'impact des couplages fluide structure à l'échelle du réseau de pores en couplant un modèle de réseau de pores à un modèle de réseau de ressorts interconnectés. Les simulations basées sur ce modèle indiquent un changement profond de la figure d'invasion par rapport au cas rigide avec l'auto-génération de chemins préférentiels lorsque les couplages sont suffisamment forts. / The work presented in this manuscript is motivated by the study of nuclear waste underground repository. In this context, we study the hyperslow drainage problem, which is related to the gas production, mainly hydrogen, taking place within the repository. Although the gas production rate is quite small, and thus the drainage hyperslow, the amount of produced gas is quite significant because the production takes place over thousands years. The study is performed within the framework of the theory of invasion percolation in a gradient. We first show that the hyperslow drainage process can be modelled using the traditional two-phase flow model based on the generalized Darcy's law. A crucial step is then to specify properly the parameters of the model. We show how they must be specified from the asymptotic behaviours of the parameters for an infinite medium as predicted by percolation theory. The obtained solution indicates that the hyperslow drainage operates in the vicinity of breakthrough pressure, which is the subject of a specific study. Furthermore, the hyperslow drainage is characterized by a weak desaturation of the medium and a great sensitivity to the model parameters in the range of high wetting fluid saturation. We also study the impact of coupling between the flow and the local deformation of porous matrix at the pore network scale from numerical simulations using a model coupling a pore network model and a deformation model based on a system of interconnected springs. The simulations indicate a major change of the invasion pattern compared to the rigid matrix with the self-generation of invasion preferential paths when the coupling is sufficiently strong.