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 Belgian Approach Towards the Study of the Compatibility of Eurobitum With the Geological Disposal Environment

2007 ◽  
Author(s):  
Elie Valcke ◽  
Robert Gens
Keyword(s):  
Radioactive Waste ◽  
Waste Management ◽  
Water Uptake ◽  
Nuclear Research ◽  
Swelling Pressure ◽  
Research Centre ◽  
Soluble Salts ◽  
Geological Disposal ◽  
Management Agency ◽  
Clay Formation

In Belgium, EUROBITUM bituminized radioactive waste containing large amount of soluble salts (NaNO3) is to be disposed of in a final repository in a clay formation. Since the emplacement of the waste will induce many interdependent processes that could negatively affect the interesting radionuclide retarding properties of the clay, the study of the compatibility of EUROBITUM is very complex. To better structure the research and to identify possible knowledge gaps, NIRAS/ONDRAF, the Belgian Radioactive Waste Management Agency, developed the safety functions and safety statements approach. In this paper, we present the application of this approach for the case of EUROBITUM. The approach is illustrated with new and old results on water uptake, swelling, swelling pressure build-up, and ageing, obtained from tests performed in the laboratories of SCK•CEN, the Belgian Nuclear Research Centre.

Perspectives on the Review of AECL's Proposal for Disposing of Canada's Nuclear Fuel Waste

1997 ◽  
Vol 506 ◽  
Author(s):  
K.W. Dormuth ◽  
P.A. Gillespie ◽  
S.H. Whitaker
Keyword(s):  
Nuclear Fuel ◽  
Environmental Assessment ◽  
Geological Disposal ◽  
The Public ◽  
Public Hearings ◽  
Points Of View ◽  
Nuclear Fuel Waste ◽  
Term Management

ABSTRACTA federal Environmental Assessment Panel has completed public hearings on the proposed concept for geological disposal of Canada's nuclear fuel waste. The Panel will make recommendations to assist the governments of Canada and Ontario in reaching decisions on the acceptability of the proposed concept and on the steps that must be taken to ensure the safe long-term management of nuclear fuel waste in Canada. It is instructive to review the background to the public hearings, to consider the issues that have been important in the public review, and to reflect on the opposing points of view presented at the hearings.

scholarly journals Multiple roles of clays in radioactive waste confinement – introduction

2019 ◽  
Vol 482 (1) ◽  
pp. 1-9
Author(s):  
Simon Norris
Keyword(s):  
Radioactive Waste ◽  
Integrated Approach ◽  
Multiple Roles ◽  
Chemical Contaminants ◽  
Geological Disposal ◽  
Clayey Material ◽  
Engineered Barriers ◽  
Host Rocks ◽  
Term Management

AbstractGeological disposal provides the safe long-term management solution for higher-activity radioactive waste. The development of a repository (or geological disposal facility) requires a systematic and integrated approach, taking into account the characteristics of the waste to be emplaced, the enclosing engineered barriers, and the host rock and its geological setting.Clays and clayey material are important in the development of many national geological disposal systems. Clays exhibit many interesting properties, and are proposed both as host rocks and as material for engineered barriers. Whatever their use, clays present various characteristics that make them high-quality barriers to the migration of radionuclides and chemical contaminants. As host rocks, clays are, in addition, hydrogeologically, geochemically and mechanically stable over geological timescales (i.e. millions of years).

Changes in Visual Acuity and Refraction in the Exfoliation Syndrome. A Five-Year Follow-up Study

2001 ◽  
Vol 11 (3) ◽  
pp. 245-251 ◽  
Author(s):  
P.M. Puska ◽  
A.H.A. Tarkkanen
Keyword(s):  
Visual Acuity ◽  
Main Type ◽  
Exfoliation Syndrome ◽  
Follow Up Study ◽  
Exfoliative Glaucoma ◽  
The Difference ◽  
Term Management ◽  
Fellow Eyes

Purpose To examine changes in visual acuity (VA) and refraction in non-glaucomatous patients with unilateral exfoliation syndrome (EXS). Methods The best corrected values for VA (Snellen acuity cards) subjectively adjusted for refraction, and IOP were measured, and the development of lens opacities was examined in 46 non-glaucomatous patients with unilateral EXS. Results After five years the rate of conversion to bilateral exfoliation was 22% and to exfoliative glaucoma 30%. There was a significant decrease in VA in the exfoliative (E) eyes (median; QI, QIII, range: 1; 0.8, 1, 0.4-1.3 vs. 0.55; 0.4, 1, 0.05-1.4, p<0.0001) and the fellow, initially non-exfoliative (NE), eyes (1; 0.9, 1, 0.3–1.3 vs. 0.7; 0.5, 0.9, 0.1–1.4, p<0.0001) and a significant myopic change in refraction in the E eyes (+1.02 ± 2.48 vs. +0.11 ± 3.06, p=0.0001) and the NE eyes (+0.99 ± 2.25 vs. +0.43 ± 2.55 D, p<0.01). At study entry the difference in refraction between the fellow eyes (refraction in the NE eye – refraction in the E eye) was −0.27 ± 1.00D. After five years it was +0.32 ± 1.44 (p 0.016), reflecting greater myopic changes in the E eyes. The main type of lens opacification was nuclear sclerosis. Conclusions In five years, significant decreases in VA and myopic shifts in refraction occurred in the E and fellow eyes. The E eyes showed significantly greater myopic changes than the fellow eyes; the cause was clearly nuclear sclerosis, which must be taken into account in the long-term management of patients with EXS.

The Renewal of HTR Development in Europe

2002 ◽  
Author(s):  
Dominique Hittner
Keyword(s):  
High Performance ◽  
Nuclear Research ◽  
Reactor Physics ◽  
Coated Particles ◽  
Economic Competitiveness ◽  
Geologic Disposal ◽  
First Results ◽  
European Nuclear ◽  
Very High

The European HTR-Technology Network (HTR-TN), created in 2000, presently groups 20 organisations from European nuclear research and industry for developing the technologies of direct-cycle modular HTRs, which presently raise a large world-wide interest, because of their high potential for economic competitiveness, natural resource sparing, safety and minimisation of the waste impacts, in line with the goals of sustainable development of Generation IV. All aspects of HTR technologies are addressed by HTR-TN, from the reactor physics to the development of materials, fuel and components. Most of this activity is supported by the European Commission in the frame of its 5th Euratom Framework Programme. The first results of HTR-TN programme are given: the analysis of the reactor physics international benchmark on the commissioning tests of HTTR (Japan), the long term behaviour of spent HTR fuel in geologic disposal conditions, the preparation of a very high burnup fuel irradiation and the development of fabrication processes for producing high performance coated particles, etc.

Long-term Corrosion of Zircaloy-4 and Zircaloy-2 by Continuous Hydrogen Measurement under Repository Condition

2013 ◽  
Vol 1518 ◽  
pp. 173-178 ◽  
Author(s):  
Tomofumi Sakuragi ◽  
Hideaki Miyakawa ◽  
Tsutomu Nishimura ◽  
Tsuyoshi Tateishi
Keyword(s):  
Corrosion Behavior ◽  
Gas Flow ◽  
Hydrogen Generation ◽  
Tetragonal Zirconia ◽  
Solution Ph ◽  
Naoh Solution ◽  
The Difference ◽  
Process Controls ◽  
Kinetics Of

ABSTRACTCorrosion behavior is a key issue for the waste disposal of irradiated metals, such as hulls and endpieces, and is considered to be a leaching source of radionuclides including C-14. However, little information about Zircaloy corrosion in anticorrosive conditions has been provided.In the present study, long-term corrosion tests of Zircaloy-4 and Zircaloy-2 were performed in assumed disposal conditions (dilute NaOH solution, pH 12.5, 303 K) by using the gas flow system for 1500 days. The corrosion rate, which was determined by measuring gaseous hydrogen and the hydrogen absorbed in Zircaloy, decreased with immersion time and was lower than the value of 2×10−2 μm/y used in performance assessment (1500-day values: 5.84×10−3 and 5.66×10−3 μm/y for Zircaloy-4, 1000-day values: 8.81×10−3 μm/y for Zircaloy-2). The difference in corrosion behavior between Zircaloy 4 and Zircaloy-2 was negligible. The average values of the hydrogen absorption ratios for Zircaloy-4 and Zircaloy-2 during corrosion were 91% and 94%, respectively.The hydrogen generation kinetics of both gas evolution and absorption into metal can be shown by a parabolic curve. This result indicates that the diffusion process controls the Zircaloy corrosion in the early corrosion stage of the present study, and that the thickness of the oxide film in this stage is limited to approximately 25 nm and may therefore be in the form of dense tetragonal zirconia.

The Use of μCT and ESEM in the Study of the Osmosis-Induced Water Uptake by Eurobitum Bituminized Radioactive Waste

2012 ◽  
Vol 18 (5) ◽  
pp. 1163-1180 ◽  
Author(s):  
An Mariën ◽  
Elie Valcke ◽  
Nele Bleyen ◽  
Maarten Van Geet ◽  
Martine Wevers
Keyword(s):  
Radioactive Waste ◽  
Water Uptake ◽  
Environmental Scanning Electron Microscopy ◽  
Nuclear Research ◽  
Constant Volume ◽  
Constant Stress ◽  
Research Centre ◽  
Environmental Scanning ◽  
Diffusion Controlled ◽  
Salt Crystals

AbstractLaboratory water uptake tests are performed at the Belgian Nuclear Research Centre SCK•CEN to obtain insight into the hydromechanical behavior of Eurobitum bituminized radioactive waste under geological disposal conditions. Small nonradioactive and radioactive Eurobitum samples are hydrated in restricted swelling conditions (i.e., nearly constant volume conditions and constant stress conditions). Microfocus X-ray computer tomography (μCT) proves to be a very suitable technique to follow up the ingress of water in the samples. μCT analyses demonstrate that, under the studied hydration conditions, the water uptake by Eurobitum samples is a diffusion controlled process. A characterization of the partially leached samples with environmental scanning electron microscopy (ESEM) shows that the hydration of salt crystals and the subsequent dilution of the salt solution result in an increase in pore size that is limited to a few tens of μm in restricted swelling conditions. The μCT and ESEM analyses allow improvement in the understanding of water uptake by Eurobitum in restricted swelling conditions. In this article we discuss the μCT and ESEM analyses of nonradioactive Eurobitum samples that were hydrated for 2 to 4 years at a constant stress of 1, 22, 33, and 44 bar or in nearly constant volume conditions.

Concrete in Engineered Barriers for Radioactive Waste Disposal Facilities: Phenomenological Study and Assessment of Long Term Performance

2013 ◽  
Author(s):  
Diederik Jacques ◽  
Norbert Maes ◽  
Janez Perko ◽  
Suresh C. Seetharam ◽  
Quoc Tri Phung ◽  
...  
Keyword(s):  
Phenomenological Study ◽  
Numerical Study ◽  
Effective Diffusivity ◽  
Nuclear Research ◽  
Radioactive Waste Disposal ◽  
Chemical Degradation ◽  
Scale Model ◽  
Research Centre ◽  
Pore Scale

The paper aims to highlight recent developments at the Belgian Nuclear Research Centre SCK•CEN in experimental and numerical study of the coupled physical-chemical behaviour of concrete subject to chemical degradation. The discussion mainly focusses on three interlinked research projects covering novel experimental methods to study the alteration of hydraulic and transport properties during carbonation and calcium leaching, a pore scale numerical model to capture microstructural changes due to the above degradation processes and a generic multiscale model aimed at determining evolution of the properties of a macrostructure over the long term. The paper also describes supplementary continuum scale numerical studies concerning concrete-clay interactions and geochemical impact on the physical structure of concrete. Preliminary findings from these studies show encouraging results such as the development of novel leaching, water permeability and diffusion apparatus, a robust pore scale model based on Lattice-Boltzmann method and a mesoscale study focused on the importance of interfacial transition zones on the effective diffusivity for linear and nonlinear diffusion problems.

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.

scholarly journals The IAGOS NO<sub><i>x</i></sub> instrument – design, operation and first results from deployment aboard passenger aircraft

2018 ◽  
Vol 11 (6) ◽  
pp. 3737-3757 ◽  
Author(s):  
Florian Berkes ◽  
Norbert Houben ◽  
Ulrich Bundke ◽  
Harald Franke ◽  
Hans-Werner Pätz ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Nitrogen Monoxide ◽  
High Time Resolution ◽  
Total Uncertainty ◽  
Autonomous Operation ◽  
First Results ◽  
The Difference ◽  
Using Data ◽  
Passenger Aircraft

Abstract. We describe the nitrogen oxide instrument designed for the autonomous operation on board passenger aircraft in the framework of the European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System). We demonstrate the performance of the instrument using data from two deployment periods aboard an A340-300 aircraft of Deutsche Lufthansa. The well-established chemiluminescence detection method is used to measure nitrogen monoxide (NO) and nitrogen oxides (NOx). NOx is measured using a photolytic converter, and nitrogen dioxide (NO2) is determined from the difference between NOx and NO. This technique allows measuring at high time resolution (4 s) and high precision in the low ppt range (NO: 2σ = 24 pptv; NOx: 2σ = 35 pptv) over different ambient temperature and ambient pressure altitude ranges (from surface pressure down to 190 hPa). The IAGOS NOx instrument is characterized for (1) calibration stability and total uncertainty, (2) humidity and chemical interferences (e.g., ozone; nitrous acid, HONO; peroxyacetyl nitrate, PAN) and (3) inter-instrumental precision. We demonstrate that the IAGOS NOx instrument is a robust, fully automated, and long-term stable instrument suitable for unattended operation on airborne platforms, which provides useful measurements for future air quality studies and emission estimates.

Sign in / Sign up

Export Citation Format

Share Document