Understanding The Mobility Of Caesium Nickel And Selenium Released From Waste Disposal Chemical Retention Mechanisms Of Degraded Cement
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Author | : Christoph Borkel |
Publisher | : |
Total Pages | : 239 |
Release | : 2016 |
Genre | : |
ISBN | : |
Cementitious materials are used to condition or stabilise waste and to build infrastructure in disposal sites. Moreover, they are envisaged to form part of engineered barrier systems as container, backfill or liner materials in radioactive waste disposal concepts. In the event of contact with water, contaminants dissolve and their mobility is influenced by the employed cementitious materials. Therefore, sound understanding of the interactions between contaminants and degrading cementitious materials in flowing water is essential for safety assessment. The aim of this study was to identify the processes affecting retention of caesium, nickel and selenium on Hardened Cement Paste (HCP) during its degradation, from sane to severely degraded states. The focus was put on the underlying mechanisms and possible remobilisation of previously retained contaminants due to the changing composition of the HCP. Caesium, as Cs(I), nickel, as Ni(II) and selenium, as Se(VI), were chosen because they are considered as safety relevant radionuclides for nuclear waste disposal, represent different chemical characteristics and their stable isotopes can be used in experiments. To address shortcomings of previous studies in this field a combined approach was developed. First, a previously used thin-layer flow-through reactor was adapted and improved for the needs of studying contaminant retention and release during degradation of the multiphase material HCP. Second, retention and degradation were studied in equilibrated batch systems as well. Regarding degradation of HCP the following results were obtained: (1) The thin-layer flow-through setup was established for degradation of HCP at far-from-equilibrium conditions and a number of relevant experimental data were obtained. (2) A kinetic degradation model satisfactorily reproduced experimental results on HCP degradation. For this, a set of dissolution rate constants of cement phases was optimised which can also be used for other modelling studies. (3) The same model also satisfactorily reproduces results from experiments with different aqueous CO2 concentrations and with different solution types, i.e. synthesised granitic groundwater (GG water) and deionised (DI) water. (4) When quantitatively comparing different solution types, degradation of HCP equilibrated with GG water is stronger than after equilibration with DI water, due to higher aqueous CO2 concentration. Further, the effects of carbonate buffering and carbonation on HCP at far-from-equilibrium conditions were identified and quantified. (5) Four characteristic stages of HCP degradation in flow-through conditions were classified, taking into account carbonate buffering effects. The different stages can be discerned on-line by measurement of pH, Ca and Si concentrations in outflow solutions. Regarding retention of Cs, Ni and Se(VI) in HCP conditioned systems the following results were obtained: (1) Caesium and selenate distribution coefficients were determined in equilibrated systems at different degradation states of HCP. (2) Caesium and selenate retention was quantified at flow conditions during continuous degradation of HCP in DI and GG water and likely retention mechanisms were narrowed down.(3) In the case of nickel, the solubility limiting phases formed in presence of HCP were identified at different degradation states. (4) The formation of a so far non-described nickel-silicate-hydrate was observed in the more degraded system at pH around 11.6. (5) The influence of different aqueous CO2 concentrations on Cs, Ni and Se(VI) retention was demonstrated to be minor. This study showed that the persistency of contaminant retention by adsorption in degrading cementitious systems is not only a question of distribution coefficients at different degradation states, but also a question of how fast these degradation states are reached.
Author | : Michael Ochs |
Publisher | : Springer |
Total Pages | : 322 |
Release | : 2015-10-17 |
Genre | : Technology & Engineering |
ISBN | : 3319236512 |
Cementitious materials are being widely used as solidification/stabilisation and barrier materials for a variety of chemical and radioactive wastes, primarily due to their favourable retention properties for metals, radionuclides and other contaminants. The retention properties result from various mineral phases in hydrated cement that possess a high density and diversity of reactive sites for the fixation of contaminants through a variety of sorption and incorporation reactions. This book presents a state of the art review and critical evaluation of the type and magnitude of the various sorption and incorporation processes in hydrated cement systems for twenty-five elements relevant for a broad range of radioactive and industrial wastes. Effects of cement evolution or ageing on sorption/incorporation processes are explicitly evaluated and quantified. While the immobilisation of contaminants by mixing-in during hydration is not explicitly addressed, the underlying chemical processes are similar. A quantitative database on the solid/liquid distribution behaviour of radionuclides and other elements in hydrated cement systems is established on the basis of a consistent review and re-evaluation of literature data. In addition to recommended values, all underlying original experimental data and key experimental info rmation are provided, which allows users to trace the given recommendations or to develop their own set of key values. This database is closely tied to the safety analysis of near surface disposal of radioactive waste in Belgium. It focuses on radioelements, toxic stable elements and heavy metals, which makes it relevant for investigations involving the interaction of radioactive and conventional contaminants with cement-based barriers.
Author | : K.L. Scrivener |
Publisher | : CRC Press |
Total Pages | : 474 |
Release | : 1997-04-17 |
Genre | : Architecture |
ISBN | : 9780419215707 |
Deterioration of cement-based materials is a continuing problem, as it results in the substantial shortening of the lives of conventional concrete structures. The main costs result from poor performance and the need for early repair. With more advanced applications, where very long service lives are essential, such as the storage of nuclear waste, an understanding of the degradation processes in order to predict long term performance is very important. this book forms the proceedings of the latest Symposia at the Materials Research Society Autumn meeting in Boston.
Author | : Food and Agriculture Organization of the United Nations |
Publisher | : Food & Agriculture Org. |
Total Pages | : 156 |
Release | : 2018-04-30 |
Genre | : Technology & Engineering |
ISBN | : 9251305056 |
This document presents key messages and the state-of-the-art of soil pollution, its implications on food safety and human health. It aims to set the basis for further discussion during the forthcoming Global Symposium on Soil Pollution (GSOP18), to be held at FAO HQ from May 2nd to 4th 2018. The publication has been reviewed by the Intergovernmental Technical Panel on Soil (ITPS) and contributing authors. It addresses scientific evidences on soil pollution and highlights the need to assess the extent of soil pollution globally in order to achieve food safety and sustainable development. This is linked to FAO’s strategic objectives, especially SO1, SO2, SO4 and SO5 because of the crucial role of soils to ensure effective nutrient cycling to produce nutritious and safe food, reduce atmospheric CO2 and N2O concentrations and thus mitigate climate change, develop sustainable soil management practices that enhance agricultural resilience to extreme climate events by reducing soil degradation processes. This document will be a reference material for those interested in learning more about sources and effects of soil pollution.
Author | : Michael I. Ojovan |
Publisher | : Elsevier |
Total Pages | : 505 |
Release | : 2011-01-24 |
Genre | : Technology & Engineering |
ISBN | : 085709095X |
Radioactive wastes are generated from a wide range of sources, including the power industry, and medical and scientific research institutions, presenting a range of challenges in dealing with a diverse set of radionuclides of varying concentrations. Conditioning technologies are essential for the encapsulation and immobilisation of these radioactive wastes, forming the initial engineered barrier required for their transportation, storage and disposal. The need to ensure the long term performance of radioactive waste forms is a key driver of the development of advanced conditioning technologies. The Handbook of advanced radioactive waste conditioning technologies provides a comprehensive and systematic reference on the various options available and under development for the treatment and immobilisation of radioactive wastes. The book opens with an introductory chapter on radioactive waste characterisation and selection of conditioning technologies. Part one reviews the main radioactive waste treatment processes and conditioning technologies, including volume reduction techniques such as compaction, incineration and plasma treatment, as well as encapsulation methods such as cementation, calcination and vitrification. This coverage is extended in part two, with in-depth reviews of the development of advanced materials for radioactive waste conditioning, including geopolymers, glass and ceramic matrices for nuclear waste immobilisation, and waste packages and containers for disposal. Finally, part three reviews the long-term performance assessment and knowledge management techniques applicable to both spent nuclear fuels and solid radioactive waste forms. With its distinguished international team of contributors, the Handbook of advanced radioactive waste conditioning technologies is a standard reference for all radioactive waste management professionals, radiochemists, academics and researchers involved in the development of the nuclear fuel cycle. Provides a comprehensive and systematic reference on the various options available and under development for the treatment and immobilisation of radioactive wastes Explores radioactive waste characterisation and selection of conditioning technologies including the development of advanced materials for radioactive waste conditioning Assesses the main radioactive waste treatment processes and conditioning technologies, including volume reduction techniques such as compaction
Author | : Cleverson Vitorio Andreoli |
Publisher | : IWA Publishing |
Total Pages | : 257 |
Release | : 2007-03-30 |
Genre | : Science |
ISBN | : 184339166X |
Sludge Treatment and Disposal is the sixth volume in the series Biological Wastewater Treatment. The book covers in a clear and informative way the sludge characteristics, production, treatment (thickening, dewatering, stabilisation, pathogens removal) and disposal (land application for agricultural purposes, sanitary landfills, landfarming and other methods). Environmental and public health issues are also fully described. About the series: The series is based on a highly acclaimed set of best selling textbooks. This international version is comprised by six textbooks giving a state-of-the-art presentation of the science and technology of biological wastewater treatment. Other titles in the series are: Volume 1: Waste Stabilisation Ponds; Volume 2: Basic Principles of Wastewater Treatment; Volume 3: Waste Stabilization Ponds; Volume 4: Anaerobic Reactors; Volume 5: Activated Sludge and Aerobic Biofilm Reactors
Author | : Food and Agriculture Organization |
Publisher | : Food & Agriculture Organization of the UN (FAO) |
Total Pages | : 0 |
Release | : 2021-06-02 |
Genre | : Environmental sciences |
ISBN | : 9789251344484 |
World soil health is under pressure from erosion, loss of soil organic carbon and biodiversity, pollution, and salinization. This report presents the status and drivers of global soil pollution, as well as recommendations to address the issue such as using bioremediation technologies.
Author | : |
Publisher | : DIANE Publishing |
Total Pages | : 132 |
Release | : 2002 |
Genre | : Arsenic wastes |
ISBN | : 1428900209 |
Author | : |
Publisher | : |
Total Pages | : 298 |
Release | : 2002 |
Genre | : Beryllium |
ISBN | : |
Author | : P A CARSON |
Publisher | : Elsevier |
Total Pages | : 389 |
Release | : 2013-10-22 |
Genre | : Technology & Engineering |
ISBN | : 008052379X |
Summarizes core information for quick reference in the workplace, using tables and checklists wherever possible. Essential reading for safety officers, company managers, engineers, transport personnel, waste disposal personnel, environmental health officers, trainees on industrial training courses and engineering students. This book provides concise and clear explanation and look-up data on properties, exposure limits, flashpoints, monitoring techniques, personal protection and a host of other parameters and requirements relating to compliance with designated safe practice, control of hazards to people's health and limitation of impact on the environment. The book caters for the multitude of companies, officials and public and private employees who must comply with the regulations governing the use, storage, handling, transport and disposal of hazardous substances. Reference is made throughout to source documents and standards, and a Bibliography provides guidance to sources of wider ranging and more specialized information. Dr Phillip Carson is Safety Liaison and QA Manager at the Unilever Research Laboratory at Port Sunlight. He is a member of the Institution of Occupational Safety and Health, of the Institution of Chemical Engineers' Loss Prevention Panel and of the Chemical Industries Association's `Exposure Limits Task Force' and `Health Advisory Group'. Dr Clive Mumford is a Senior Lecturer in Chemical Engineering at the University of Aston and a consultant. He lectures on several courses of the Certificate and Diploma of the National Examining Board in Occupational Safety and Health. [Given 5 star rating] - Occupational Safety & Health, July 1994 - Loss Prevention Bulletin, April 1994 - Journal of Hazardous Materials, November 1994 - Process Safety & Environmental Prot., November 1994