Modelling of the Evolution of Porewater Chemistry in a Cementitious Repository

1989 ◽  
Vol 176 ◽  
Author(s):  
A. Haworth ◽  
S.M. Sharland ◽  
C.J. Tweed
Keyword(s):  
Nuclear Waste ◽  
Transport Model ◽  
Near Field ◽  
Intermediate Level ◽  
Current Concept ◽  
Release Rates ◽  
Chemistry Transport Model ◽  
Porewater Chemistry ◽  
The Uk ◽  
Cement Formulation

ABSTRACTThe current concept for disposal of low- or intermediate-level nuclear waste in the UK includes a largely cementitious backfill. An important factor in determining nuclide release rates from the repository is the pH in the near-field. In this paper, we describe development of a coupled chemistry/transport model of cement degradation and its application in determining the evolution of the chemistry within the repository. In particular, the effect of the cement formulation and interaction with groundwater species on the evolution of the pH is examined. The model is sufficiently flexible to consider a number of different repository scenarios.

scholarly journals The dissolution of simulant vitrified intermediate level nuclear waste in young cement water

MRS Advances ◽  
2020 ◽  
Vol 5 (3-4) ◽  
pp. 131-140
Author(s):  
Colleen Mann ◽  
Jeremy R. Eskelsen ◽  
Donovan N. Leonard ◽  
Eric Pierce ◽  
Claire L Corkhill
Keyword(s):  
Nuclear Waste ◽  
Alkaline Earth ◽  
Water Solution ◽  
Cementitious Materials ◽  
Intermediate Level ◽  
Short Term ◽  
Alkaline Earth Elements ◽  
Altered Layer ◽  
Safety Case ◽  
The Uk

AbstractIt is pertinent to the safety case for geological disposal in the UK that the behaviour of vitrified wastes in proximity to cementitious materials is understood. In this study, vitrified simulant intermediate level nuclear waste (ILW) was subject to dissolution in a synthetic cement water solution to simulate disposal conditions. Results show that the presence of alkali / alkaline earth elements in the cementitious solution can be favourable, at least in the short-term, leading to lower dissolution rates associated with incorporation of these elements into the altered layer of the glass.

scholarly journals Nitrogen deposition in the UK at 1 km resolution from 1990 to 2017

2021 ◽  
Author(s):  
Samuel James Tomlinson ◽  
Edward John Carnell ◽  
Anthony J. Dore ◽  
Ulrike Dragosits
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
N Deposition ◽  
Nitrogen Oxide Emissions ◽  
Chemistry Transport Model ◽  
Wet And Dry Deposition ◽  
Coarse Spatial Resolution ◽  
Reduce Emissions ◽  
The Uk

Abstract. An atmospheric chemistry transport model (FRAME) is used here to calculate the UK N deposition for the years 1990–2017. Reactive nitrogen (N) deposition is a threat that can lead to adverse effects on the environment and human health. In Europe, substantial reductions in N deposition from nitrogen oxide emissions have been achieved in recent decades, this paper quantifies reductions in UK N deposition following the N emissions peak in 1990. In the UK, estimates of N deposition are typically available at a coarse spatial resolution (typically 5 km × 5 km grid resolution) and it is often difficult to compare estimates between years due to methodological changes in emission estimates. Through efforts to reduce emissions of N from industry, traffic, and agriculture, this study predicts that UK N deposition has reduced from 465 kt N in 1990 to 278 kt N in 2017. However, as part of this overall reduction, there are non-uniform changes for wet and dry deposition of reduced N (NHx) and oxidised N (NOy). In 2017, it is estimated 59 % of all N deposition is in the form of reduced N, a change from 35 % in 1990. This dataset uses 28 years of emissions data from 1990 to 2017 to produce the first long-term dataset of 28 years of N deposition at 1 km × 1 km resolution in the UK.

Equilibrium Leach Testing of Intermediate Level Waste

1988 ◽  
Vol 127 ◽  
Author(s):  
W Heafield ◽  
P Barlow ◽  
A Hunt
Keyword(s):  
Near Field ◽  
Intermediate Level ◽  
Degree Of Protection ◽  
Leach Test ◽  
Additional Protection ◽  
Chemical States ◽  
Equilibrium Concentrations ◽  
The Uk ◽  
Static Conditions ◽  
High Degree

ABSTRACTExperiments examining the leach characteristics of encapsulated Intermediate Level Wastes in repository near-field conditions have been undertaken in the UK since 1982. The Equilibrium Leach Test was developed in order to provide a realistic static leach test for the measurement of equilibrium concentrations and chemical states of individual nuclides within a particular waste, or combination of wastes, and the components of the near-field barriers of a repository, after water has ingressed into the system. The significant components of the near-field ie waste material, waste matrix and repository backfill are equilibrated with water under static conditions.Results illustrate the high degree of protection afforded by the near-field, which under repository conditions will be complemented by the additional protection of the far-field and the biosphere. Analytical results show that a cement based matrix and cementitious backfill provide the lowest radionuclide concentrations, for long lived radionuclides.

Modelling of the Degradation of Cement in a Nuclear Waste Repository

1988 ◽  
Vol 127 ◽  
Author(s):  
A. Haworth ◽  
S. M. Sharland ◽  
C. J. Tweed
Keyword(s):  
Nuclear Waste ◽  
Transport Model ◽  
Thermodynamic Description ◽  
Nuclear Waste Repository ◽  
General Corrosion ◽  
Chemistry Transport Model ◽  
High Ph ◽  
Preliminary Model ◽  
Waste Repository ◽  
Aqueous Species

ABSTRACTThe current UK concept for a low- or intermediate-level nuclear waste repository includes a largely cementitious backfill. The cement provides a high pH environment in which the general corrosion rate of the metal canisters is reduced and the solubilities of many nuclides low. It has previously been assumed that this high pH will exist for a period of 107 years, however cement will degrade due to leaching of the solid components and attack from aqueous species in groundwater. In this paper we describe the preliminary stages of a model of the degradation of cement in a repository. The modelling involves the incorporation of a thermodynamic description of cement[2] into the static code PHREEQE[5]. This is then used in a coupled chemistry-transport model of simple leaching of cement using the code CHEQMATE[4]. This preliminary modelling also provides a useful verification of CHEQMATE as a direct comparison with a THCCDM (a coupled code based on CHEMTRN) model is possible. Results from this preliminary model suggest that the fall in pH due to leaching is slow. The model is sufficiently flexible to form the basis of more detailed investigations of the effect of groundwater interactions on the degradation of cement.

scholarly journals Nitrogen deposition in the UK at 1 km resolution from 1990 to 2017

2021 ◽  
Vol 13 (10) ◽  
pp. 4677-4692
Author(s):  
Samuel J. Tomlinson ◽  
Edward J. Carnell ◽  
Anthony J. Dore ◽  
Ulrike Dragosits
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
N Deposition ◽  
Full Data ◽  
Chemistry Transport Model ◽  
Wet And Dry Deposition ◽  
Coarse Spatial Resolution ◽  
Reduce Emissions ◽  
The Uk

Abstract. An atmospheric chemistry transport model (FRAME) is used here to calculate annual UK N deposition for the years 1990–2017, at a 1 km × 1 km resolution. Reactive nitrogen (N) deposition is a threat that can lead to adverse effects on the environment and human health. In Europe, substantial reductions in N deposition from nitrogen oxide emissions have been achieved in recent decades. This paper quantifies reductions in UK N deposition following the N emissions peak in 1990. In the UK, estimates of N deposition are typically available at a coarse spatial resolution (typically 5 km × 5 km grid resolution), and it is often difficult to compare estimates between years due to methodological changes in emission estimates. Through efforts to reduce emissions of N from industry, traffic, and agriculture, this study predicts that UK N deposition has reduced from 465 kt N in 1990 to 278 kt N in 2017. However, as part of this overall reduction, there are non-uniform changes for wet and dry deposition of reduced N (NHx) and oxidised N (NOy). In 2017, it is estimated 59 % of all N deposition is in the form of reduced N, a change from 35 % in 1990. This dataset uses 28 years of emissions data from 1990 to 2017 to produce the first long-term dataset of 28 years of N deposition at 1 km × 1 km resolution in the UK. Full data are available at https://doi.org/10.5285/9b203324-6b37-4e91-b028-e073b197fb9f (Tomlinson et al., 2020).

scholarly journals Variability of springtime transpacific pollution transport during 2000–2006: the INTEX-B mission in the context of previous years

2010 ◽  
Vol 10 (3) ◽  
pp. 1345-1359 ◽  
Author(s):  
G. G. Pfister ◽  
L. K. Emmons ◽  
D. P. Edwards ◽  
A. Arellano ◽  
T. Campos ◽  
...  
Keyword(s):  
Transport Model ◽  
Pollution Transport ◽  
Chemistry Transport Model ◽  
Pollution Levels ◽  
Annual Variability ◽  
Source Regions ◽  
Time Period ◽  
The Pacific ◽  
The Us ◽  
Transport Experiment

Abstract. We analyze the transport of pollution across the Pacific during the NASA INTEX-B (Intercontinental Chemical Transport Experiment Part B) campaign in spring 2006 and examine how this year compares to the time period for 2000 through 2006. In addition to aircraft measurements of carbon monoxide (CO) collected during INTEX-B, we include in this study multi-year satellite retrievals of CO from the Measurements of Pollution in the Troposphere (MOPITT) instrument and simulations from the chemistry transport model MOZART-4. Model tracers are used to examine the contributions of different source regions and source types to pollution levels over the Pacific. Additional modeling studies are performed to separate the impacts of inter-annual variability in meteorology and dynamics from changes in source strength. Interannual variability in the tropospheric CO burden over the Pacific and the US as estimated from the MOPITT data range up to 7% and a somewhat smaller estimate (5%) is derived from the model. When keeping the emissions in the model constant between years, the year-to-year changes are reduced (2%), but show that in addition to changes in emissions, variable meteorological conditions also impact transpacific pollution transport. We estimate that about 1/3 of the variability in the tropospheric CO loading over the contiguous US is explained by changes in emissions and about 2/3 by changes in meteorology and transport. Biomass burning sources are found to be a larger driver for inter-annual variability in the CO loading compared to fossil and biofuel sources or photochemical CO production even though their absolute contributions are smaller. Source contribution analysis shows that the aircraft sampling during INTEX-B was fairly representative of the larger scale region, but with a slight bias towards higher influence from Asian contributions.

scholarly journals The On-Line Integrated Mesoscale Chemistry Model BOLCHEM

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 192
Author(s):  
Rita Cesari ◽  
Tony Christian Landi ◽  
Massimo D’Isidoro ◽  
Mihaela Mircea ◽  
Felicita Russo ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Transport Model ◽  
Horizontal Resolution ◽  
Integration Step ◽  
Chemistry Transport Model ◽  
European Environmental Agency ◽  
On Line ◽  
One Year ◽  
Pm2.5 And Pm10 ◽  
Monitoring Service

This work presents the on-line coupled meteorology–chemistry transport model BOLCHEM, based on the hydrostatic meteorological BOLAM model, the gas chemistry module SAPRC90, and the aerosol dynamic module AERO3. It includes parameterizations to describe natural source emissions, dry and wet removal processes, as well as the transport and dispersion of air pollutants. The equations for different processes are solved on the same grid during the same integration step, by means of a time-split scheme. This paper describes the model and its performance at horizontal resolution of 0.2∘× 0.2∘ over Europe and 0.1∘× 0.1∘ in a nested configuration over Italy, for one year run (December 2009–November 2010). The model has been evaluated against the AIRBASE data of the European Environmental Agency. The basic statistics for higher resolution simulations of O3, NO2 and particulate matter concentrations (PM2.5 and PM10) have been compared with those from Copernicus Atmosphere Monitoring Service (CAMS) ensemble median. In summer, for O3 we found a correlation coefficient R of 0.72 and mean bias of 2.15 over European domain and a correlation coefficient R of 0.67 and mean bias of 2.36 over Italian domain. PM10 and PM2.5 are better reproduced in the winter, the latter with a correlation coefficient R of 0.66 and the mean bias MB of 0.35 over Italian domain.

scholarly journals First-of-a-kind muography for nuclear waste characterization

2018 ◽  
Vol 377 (2137) ◽  
pp. 20180048 ◽  
Author(s):  
David Mahon ◽  
Anthony Clarkson ◽  
Simon Gardner ◽  
David Ireland ◽  
Ramsey Jebali ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
Imaging System ◽  
Academic Research ◽  
Cosmic Ray ◽  
Laboratory Facility ◽  
Waste Container ◽  
High Resolution Images ◽  
And Performance ◽  
The Uk ◽  
The University

In the last decade, there has been a surge in the number of academic research groups and commercial companies exploiting naturally occurring cosmic-ray muons for imaging purposes in a range of industrial and geological applications. Since 2009, researchers at the University of Glasgow and the UK National Nuclear Laboratory (NNL) have pioneered this technique for the characterization of shielded nuclear waste containers with significant investment from the UK Nuclear Decommissioning Authority and Sellafield Ltd. Lynkeos Technology Ltd. was formed in 2016 to commercialize the Muon Imaging System (MIS) technology that resulted from this industry-funded academic research. The design, construction and performance of the Lynkeos MIS is presented along with first experimental and commercial results. The high-resolution images include the identification of small fragments of uranium within a surrogate 500-litre intermediate level waste container and metal inclusions within thermally treated GeoMelt® R&D Product Samples. The latter of these are from Lynkeos' first commercial contract with the UK National Nuclear Laboratory. The Lynkeos MIS will be deployed at the NNL Central Laboratory facility on the Sellafield site in Summer 2018 where it will embark upon a series of industry trials. This article is part of the Theo Murphy meeting issue ‘Cosmic-ray muography’.

Aerosol Dynamics Modelling in the Regional Chemistry Transport Model System Eurad

1998 ◽  
pp. 721-722
Author(s):  
Ingmar J. Ackermann ◽  
Heinz Hass ◽  
A. Ebel ◽  
M. Memmesheimer ◽  
H. J. Jakobs
Keyword(s):  
Transport Model ◽  
Model System ◽  
Chemistry Transport Model ◽  
Aerosol Dynamics ◽  
Dynamics Modelling

scholarly journals Top-Down NOX Emissions of European Cities Based on the Downwind Plume of Modelled and Space-Borne Tropospheric NO2 Columns

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2893 ◽  
Author(s):  
Willem W. Verstraeten ◽  
Klaas Folkert Boersma ◽  
John Douros ◽  
Jason E. Williams ◽  
Henk Eskes ◽  
...  
Keyword(s):  
Urban Areas ◽  
Transport Model ◽  
Nox Emissions ◽  
Inventory Data ◽  
Ozone Monitoring Instrument ◽  
Top Down ◽  
Chemistry Transport Model ◽  
European Cities ◽  
Tropospheric No2

Top-down estimates of surface NOX emissions were derived for 23 European cities based on the downwind plume decay of tropospheric nitrogen dioxide (NO2) columns from the LOTOS-EUROS (Long Term Ozone Simulation-European Ozone Simulation) chemistry transport model (CTM) and from Ozone Monitoring Instrument (OMI) satellite retrievals, averaged for the summertime period (April–September) during 2013. Here we show that the top-down NOX emissions derived from LOTOS-EUROS for European urban areas agree well with the bottom-up NOX emissions from the MACC-III inventory data (R2 = 0.88) driving the CTM demonstrating the potential of this method. OMI top-down NOX emissions over the 23 European cities are generally lower compared with the MACC-III emissions and their correlation is slightly lower (R2 = 0.79). The uncertainty on the derived NO2 lifetimes and NOX emissions are on average ~55% for OMI and ~63% for LOTOS-EUROS data. The downwind NO2 plume method applied on both LOTOS-EUROS and OMI tropospheric NO2 columns allows to estimate NOX emissions from urban areas, demonstrating that this is a useful method for real-time updates of urban NOX emissions with reasonable accuracy.

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