Osmosis: the key process that drives water uptake and swelling of Eurobitum Bituminized Radioactive Waste

MRS Advances ◽  
2016 ◽  
Vol 1 (62) ◽  
pp. 4109-4115
Author(s):  
K. Hendrix ◽  
N. Bleyen ◽  
S. Smets ◽  
W. Verwimp ◽  
X. Sillen ◽  
...  
Keyword(s):  
Water Activity ◽  
Water Uptake ◽  
Management Option ◽  
Boom Clay ◽  
Swelling Rate ◽  
Hygroscopic Salts ◽  
Clay Formation ◽  
Term Management ◽  
Pressure Evolution

ABSTRACTIn Belgium, the preferred long-term management option for Eurobitum bituminized ILW is its final disposal in a geologically stable clay formation such as the Boom Clay, which is studied as a reference host formation. After disposal, clay pore water will infiltrate the secondary concrete waste containers filled each with ten Eurobitum drums. Eurobitum contains hygroscopic salts, mostly NaNO3 (20-30 wt%) and CaSO4 (4-6 wt%), and thus will take up water and swell. If swelling is hindered, a pressure will be exerted on the concrete container and ultimately on the surrounding Boom Clay, possibly inducing stresses in the clay close to the disposal galleries. To improve our understanding of these processes, water uptake tests are ongoing in which inactive Eurobitum is contacted with 0.1 M KOH (representing young cement water). These tests suggest that the swelling is mainly driven by osmosis. This understanding was validated in the presented research by varying the water activity of the leachant in water uptake tests in both constant stress and constant volume conditions. After a stable swelling rate was reached in contact with 0.1 M KOH, the leachant was switched in the following order: nearly saturated (∼7.8 M) NaNO3 – 0.1 M KOH – nearly saturated NaNO3 – 4 M NaNO3 – 0.1 M KOH. The changes in swelling rate and pressure evolution correlated nicely to the changes in water activity. This confirms that osmosis is the key process governing the swelling of Eurobitum.

Static dissolution tests of α-doped UO2 under repository relevant conditions: Influence of Boom Clay and α-activity on fuel dissolution rates

2006 ◽  
Vol 932 ◽  
Author(s):  
Sonia Salah ◽  
Christelle Cachoir ◽  
Karel Lemmens ◽  
Norbert Maes
Keyword(s):  
Clay Fraction ◽  
Dissolution Kinetics ◽  
Spent Fuel ◽  
Dissolution Rates ◽  
Retention Capacity ◽  
Boom Clay ◽  
Dissolution Tests ◽  
Clay Formation ◽  
Α Activity

ABSTRACTSince reprocessing is no longer the reference policy in Belgium, studies on the direct disposal of spent fuel in a clay formation have gained increased interest in the last years. In order to determine to what extent the clay properties and the α-activity influence the dissolution kinetics of spent fuel for the long term disposal, static dissolution tests have been performed on 5 different types of α-doped UO2, representing a PWR fuel with a burn-up of 45 or 55 GWd · tHM−1 and fuel ages ranging between 150 and 90,000 years, in different Boom Clay (BC) media at room temperature and in an anoxic atmosphere for 90 to 720 days. The uranium activity in the clay fraction over time was found to be much higher than the U-activity in the leachates, which has been mainly ascribed to the high retention capacity of the BC. The average dissolution rate between 0 and 90 days obtained for the 5 types of α-doped UO2 were all found to be high and quite similar at ~263 µg · m−2 · d−1and a “longer-term” rate (181 to 720 days) ranging between zero and 15 µg · m−2· d−1. These results suggest that the activity of the fuels does not seem to have an effect on the UO2 dissolution rates under the considered test conditions. In order to study the partition/redistribution of U during UO2dissolution, sequential extraction experiments were performed. Results of the latter have provided a better mechanistic understanding of BC/spent fuel interaction processes as well as information on the role of the different minerals controlling the U-retention/immobilization.

The osmosis-induced swelling and NaNO3 leaching of radioactive and artificially aged Eurobitum bituminized waste

2012 ◽  
Vol 1475 ◽  
Author(s):  
An Mariën ◽  
Elie Valcke ◽  
Nele Bleyen ◽  
Steven Smets
Keyword(s):  
Water Uptake ◽  
Nuclear Research ◽  
Research Centre ◽  
Permeable Membrane ◽  
Geological Disposal ◽  
First Results ◽  
The Difference ◽  
Kinetics Of ◽  
Term Management

ABSTRACTThe behavior of Eurobitum bituminized radioactive waste under geological disposal conditions is studied in water uptake tests at the Belgian Nuclear Research Centre SCK•CEN to assess the feasibility of geological disposal for the long-term management of this waste. The hydro-mechanical behavior of this waste is affected by the continuous evolution of the rheological properties of bitumen due to radio-oxidation (i.e. ageing).The effect of the bitumen ageing degree on the kinetics of the water uptake, swelling and NaNO3 leaching is investigated in water uptake tests with ∼30 years old radioactive samples and inactive samples that were artificially aged. The first results of swelling and NaNO3 leaching of (i) radioactive samples that have been hydrated for more than 2 years at a constant total stress of 2.2 MPa, and (ii) a thermally aged sample that has been hydrated for ∼1.5 years under nearly zero effective stress conditions, revealed lower swelling and higher leach rates for these samples compared to non-aged samples. The effect of ageing on the osmotic efficiency of bitumen as a semi-permeable membrane is less pronounced when swelling of the samples is limited, and changes in time, probably because of the formation of low porosity layers, which seems to mask the difference in bitumen membrane efficiency of aged and non-aged bituminized waste.

The Second Safety Assessment and Feasibility Interim Report (SAFIR 2 Report) on HLW Disposal in Boom Clay: Overview of the Belgian Programme

2003 ◽  
Vol 807 ◽  
Author(s):  
Robert Gens ◽  
Philippe Lalieux ◽  
Peter De Preter ◽  
Ann Dierckx ◽  
Johan Bel ◽  
...  
Keyword(s):  
Safety Assessment ◽  
State Of The Art ◽  
Technical Feasibility ◽  
Geological Disposal ◽  
Boom Clay ◽  
Safety Case ◽  
Clay Formation ◽  
Main Barrier

ABSTRACTONDRAF/NIRAS – the Belgian radioactive waste management agency – has published in 2001 the SAFIR 2 report on request of the authorities. The SAFIR 2 report is to be considered as a state-of-the art report and not as a complete safety case. This report gives an overview of the Belgian R&D program related to the geological disposal of HLW and ILW for the period 1990–2000 in the Boom Clay (reference host rock). The three main outcomes of the SAFIR 2 report on which this paper will be more specifically focusing, are the following (including results reported after 2000): long-term safety functions, confirmation of the role of the Boom Clay formation as the main barrier and identification of practical difficulties with respect to technical feasibility (repository design).

Long-Term Issues for Indefinite Surface Storage of Intermediate and Some Low Level Radioactive Waste in the UK

2003 ◽  
Author(s):  
Samantha King
Keyword(s):  
Radioactive Waste ◽  
Waste Management ◽  
Radioactive Wastes ◽  
Management Option ◽  
Radioactive Waste Management ◽  
Scoping Study ◽  
Low Level ◽  
The Uk ◽  
Term Management

Nirex is the organisation responsible for long-term radioactive waste management in the UK. Our mission is to provide the UK with safe, environmentally sound and publicly acceptable options for the long-term management of radioactive materials. Nirex is therefore researching various options for the long-term management of radioactive wastes/materials in order to identify the relevant issues with regard to the feasibility of options, and the research, development and stakeholder dialogue necessary to address these issues. The UK policy for the long-term management of solid radioactive waste is currently undergoing review. In September 2001, the UK Government Department for Environment, Food and Rural Affairs (Defra) and the Devolved Administrations for Scotland, Wales and Northern Ireland launched a public consultation on ‘Managing Radioactive Waste Safely’ (MRWS) [1]. The aim of this consultation was to start a process that will ultimately lead to the implementation of a publicly acceptable radioactive waste management policy. The MRWS programme of action proposed by Government includes a “stakeholder” programme of public debate backed by research to examine the different radioactive waste management options, and to recommend the preferred option, or combination of options. The options of storage above ground and underground are expected to be among the options examined. In the UK, radioactive wastes are currently held in surface stores, at over 30 locations in the UK, pending a decision on their long-term management. These stores were originally designed to have lifetimes of up to 50 years, but due to uncertainty regarding the longer term management of such wastes, extending the life of stores to 100 years is now being considered. This paper describes a preliminary scoping study to identify the long-term issues associated with surface storage of intermediate-level radioactive waste (ILW), and certain low-level waste (LLW) indefinitely in the UK. These wastes contain radionuclides with half lives that can range up to a million years or more, it was therefore assumed, for the purposes of this scoping study, that wastes would need to be managed over a period of at least one million years. An indefinite surface storage concept will require institutional stability and encompasses the principle of guardianship. It is based on a rolling present where each generation is required to monitor and, as necessary, repackage the waste and refurbish/replace storage buildings over a period of at least one million years. Each generation will also need to decide whether to continue with surface storage or implement another long-term management option. The aims of the scoping study were to: i) Investigate the implications of indefinite surface storage of waste packages through consideration of the facility specification, design and assessment. This framework is common to all Nirex radioactive waste management option studies, and provides a common basis for comparison. ii) Identify the social and ethical issues related to indefinite storage, including the principles and values that some stakeholders believe are met by the surface storage option.

Acupuncture and Chronic Pain Management

2017 ◽  
Vol 35 (1) ◽  
pp. 117-134 ◽  
Author(s):  
Ladan Eshkevari
Keyword(s):  
Chronic Pain ◽  
Pain Management ◽  
Primary Reason ◽  
Chronic Pain Management ◽  
Management Option ◽  
Social Burden ◽  
Severe Chronic Pain ◽  
Term Management

According to National Institute of Health Pathways to Prevention Workshop (2014), chronic pain affects an estimated 100 million Americans, with approximately 25 million people experiencing moderate to severe chronic pain, which negatively impacts their ability to function leading to a diminished quality of life. Pain is the primary reason Americans are on disability, which adds to the economic and social burden of suffering for the nation. Chronic pain costs are estimated to be between $560 and $630 billion per year. An estimated 5 to 8 million Americans use opioids for long-term management of chronic pain, which can have deleterious effects on their lives including addiction. Recent evidence suggests that acupuncture, a treatment modality that has been used worldwide for over 2,000 years, may provide a useful pain management option for those who suffer from chronic pain. The investigation into its mechanism of action and efficacy remains elusive, but promising.

In Situ Migration Experiments in the Boom Clay at Mol ; Experimental Method and Preliminary Results

1988 ◽  
Vol 127 ◽  
Author(s):  
M. Put ◽  
M. Monsecour ◽  
A. Fonteyne ◽  
H. Yoshida ◽  
P. De Regge
Keyword(s):  
Radioactive Waste ◽  
First Generation ◽  
Far Field ◽  
Radioactive Tracers ◽  
Experimental Conditions ◽  
Boom Clay ◽  
Long Term Experiments ◽  
Clay Formation

ABSTRACTA first generation of underground migration experiments is described, consisting of labelled clay cores emplaced in boreholes drilled in the Boom clay formation. The boreholes are sealed by natural convergence of the clay and porewater percolates through the labelled clay cores which are consolidated in situ. After monitoring of the radioactive tracers in the percolating porewater, the experiment is retrieved from the borehole and the tracer profile is measured in the clay cores. With the exception of accelerated porewater flow, due to the existence of a high hydraulic head around the underground gallery, the experimental conditions are close to those expected in the far-field of a closed repository for radioactive waste. The main advantage of this approach is the availability of real porewater during relatively long-term experiments. Results are reported for the experiments performed with europium and strontium tracers.

Functional Requirements and Performance Assessment: Application to the Case of Spent Fuel Disposal in Clay

2001 ◽  
Author(s):  
Jan Marivoet ◽  
Xavier Sillen ◽  
Peter De Preter
Keyword(s):  
Molecular Diffusion ◽  
Slow Release ◽  
Near Field ◽  
Functional Requirements ◽  
Spent Fuel ◽  
Systematic Analysis ◽  
Boom Clay ◽  
Safety Function ◽  
Clay Formation

Abstract Geological repository systems for the disposal of radioactive waste are based on a multi-barrier design. Individual barriers contribute in different ways to the overall long-term performance of the repository system, and furthermore, the contribution of each barrier can considerably change with time. In a systematic analysis of the functional requirements for achieving long-term safety a number of basic safety functions can be defined: physical confinement, retardation / slow release, dispersion / dilution and limited accessibility. In the case of the geological disposal of spent fuel in a clay formation a series of barriers are designed or chosen to contribute to the realisation of the basic safety functions. The physical confinement is realised by the watertight, high-integrity container, which prevents contact between groundwater and the confined radionuclides. In first instance the retardation / slow release function is realised by the slow dissolution of the waste matrix and by the limited solubility of many elements in the near field. However, the natural clay barrier provides the main contribution to this safety function. The migration of radionuclides through the Boom Clay is mainly due to molecular diffusion, which is an extremely slow process. Furthermore, many elements are strongly sorbed by the clay minerals what makes their migration even much slower. The dispersion / dilution function mainly occurs in the aquifer and the rivers draining the aquifer in the surroundings of the disposal system. Various performance indicators are used to quantify the contributions of each safety function and to explain the functioning of the repository system.

Processes Related to the Water Uptake by EUROBITUM Bituminised Radioactive Waste: Theoretical Considerations and First Experimental Results

2008 ◽  
Vol 1107 ◽  
Author(s):  
An Mariën ◽  
Steven Smets ◽  
Xiangling Li ◽  
Elie Valcke
Keyword(s):  
Radioactive Waste ◽  
Water Uptake ◽  
Swelling Pressure ◽  
Management Program ◽  
Constant Volume ◽  
Constant Stress ◽  
Stress Tests ◽  
Permeable Membrane ◽  
Boom Clay ◽  
Clay Formation

AbstractAccording to the present Belgian radioactive waste management program, Eurobitum bituminised radioactive waste will be disposed of in a geologically stable underground clay formation. The Boom Clay is studied as a potential host formation because of its low diffusion and high retention properties towards radionuclides. The presence of the radioactive waste should not disturb these properties. Due to the presence of hygroscopic salts (25 to 30 weight% NaNO3), Eurobitum will take up pore water which will result in a swelling and possibly in a very high swelling pressure. First scoping calculations suggest that the swelling pressure exerted to Boom Clay should remain below 7 to 8 MPa to avoid the formation of fractures. If the bitumen in EUROBITUM behaved like a perfect semi-permeable membrane and if no swelling were allowed after the dissolution of NaNO3 into a saturated solution of 10.8 M, osmotic pressures of ∼50 MPa could be attained. To better understand the interaction between the swelling Eurobitum and the host formation, coupled hydro-chemical-mechanical constitutive laws for Eurobitum have to be developed. To this purpose, water uptake tests under constant volume (‘confined’) and constant stress (‘semi-confined’) conditions are being performed. After ∼2 years of hydration of small inactive Eurobitum samples in constant volume conditions, the swelling pressure has raised to ∼12 MPa. The volume of samples that can swell against counter pressures of 2.2, 3.3, or 4.4 MPa (constant stress tests) increased with ∼5 to 11 volume%, independently of the applied counter pressure. Approximately 10 weight% of the initial NaNO3 content has been leached.

Testing Safety and Performance Indicators in an Assessment of the Long-Term Performance of the Geological Disposal of Spent Fuel in Boom Clay

2003 ◽  
Author(s):  
Xavier Sillen ◽  
Jan Marivoet ◽  
Wim Cool ◽  
Peter de Preter
Keyword(s):  
Dose Rate ◽  
Performance Indicators ◽  
Spent Fuel ◽  
Geological Disposal ◽  
Boom Clay ◽  
And Performance ◽  
The Individual ◽  
High Level ◽  
Clay Formation

The classical numerical output, or indicator, from assessments of the long-term safety of geological disposal systems for high-level radioactive waste is the individual effective dose rate. This indicator is an estimate of the possible individual health detriment and it is commonly compared to regulatory limits for assessing the safety of other nuclear activities as well, such as medical and industrial activities. As a safety indicator, the individual dose rate provides an estimate of the overall safety of the disposal system. However, because of the time frames involved in safety assessments of geological disposal systems, the need arises of complementary safety indicators that could be less affected by uncertainties like those associated with future human behaviour or the effects of climate change on the biosphere and the aquifers. Such alternative safety indicators can be, for example, radionuclide concentrations in the groundwater or fluxes to the biosphere due to a repository. Safety indicators only tell how globally safe a disposal system is. For confidence building, performance indicators can be used in addition to tell how the system works. In particular, performance indicators such as fluxes, activities or activity concentrations of selected radionuclides can show how the different components of the system fulfil their safety functions and contribute to the overall safety. The SPIN project of the European Commission assessed the usefulness of seven safety indicators and fourteen performance indicators by testing them in four actual assessments of disposal systems in granite formations. In this paper, indicators calculated from an assessment of the disposal of spent fuel in the poorly indurated Boom Clay formation are presented. Conclusions from the SPIN project that hold for repositories in clays are highlighted, as well as results that illustrate differences between the granite and clay disposal options. Finally, various performance and safety indicators are combined into a logical sequence to comprehensively present, and explain, the results of a safety assessment.

Study of the Processes Related to the Water Uptake of Eurobitum Bituminized Radioactive Waste: Effect of Salt Concentration

2009 ◽  
Vol 1193 ◽  
Author(s):  
An Mariën ◽  
Steven Smets ◽  
Elie Valcke
Keyword(s):  
Water Uptake ◽  
High Pressures ◽  
Salt Content ◽  
Environmental Scanning Electron Microscopy ◽  
Constitutive Law ◽  
Pressure Increase ◽  
Environmental Scanning ◽  
Boom Clay ◽  
Salt Crystals ◽  
Hygroscopic Salts

AbstractA coupled hydro-chemical-mechanical constitutive law for the Belgian Eurobitum bituminized waste is being developed by the International Centre for Numerical Methods and Engineering (Polytechnical University of Cataluña, Spain) to contribute to the study of the compatibility of Eurobitum with Boom Clay as a geological disposal environment. A large experimental programme is ongoing at SCK•CEN to support the development of a constitutive law for Eurobitum. Water uptake tests are being performed under different conditions to obtain insights in the parameters that influence the water uptake behaviour of Eurobitum. Furthermore, Environmental Scanning Electron Microscopy and microfocus X-ray Computer Tomography are used to characterize hydrated samples in order to improve the understanding of the water uptake processes.The salt content, the distribution of the salt crystals, and the membrane efficiency in the Eurobitum samples affect the swelling and pressure increase rate. High membrane efficiencies and a large amount of hygroscopic salts inside the Eurobitum samples result in very high pressures when almost no swelling is allowed. The pressure in small inactive samples with 28 wt.% NaNO3has risen to ∼19 MPa after ∼3 years of hydration in nearly constant volume conditions. Slower pressure increase rates are being measured for samples with 6, 12, 18, and 33 wt.% NaNO3.

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