BIogeochemical Gradients and RADionuclide transport. BIGRAD
Lead Research Organisation:
Diamond Light Source
Department Name: Science Division
Abstract
Over 50+ years of nuclear power generation and weapons development, the UK has created large quantities of radioactive wastes. In terms of total volume, the largest fraction (> 90 %) of the higher activity waste is Intermediate Level Waste (ILW). ILW does not produce heat but contains long-lived radioisotopes, and so cannot be disposed of near the Earth's surface. The Government has recently decided that the UK's ILW should be disposed of underground (200 - 1000 m) in a 'Geological Disposal Facility' (GDF). The safety of a GDF depends on slowing the return of radioactivity from the GDF to Earth surface. It is therefore key to understand the processes which control the movement of radioactivity out of the GDF and through the surrounding rock. The UK's ILW is very diverse and includes discarded nuclear fuel, the metal containers used to hold fuel, as well as sludges and organic debris produced when processing these radioactive materials. The UK has treated many of these radioactive wastes by immobilising them in cement and a substantial fraction of ILW has now been cemented and awaits disposal. Once the wastes have been placed in the GDF, the intention is to backfill the remaining space with cement. No site has been identified for UK wastes as yet, but it is expected that the site will be under the water table and therefore be wet. This means that, after the waste is emplaced, the GDF will rewet as groundwater percolates through the wastes. Over a long time (from hundreds to millions of years) the ILW and its steel containers will degrade, and the cement will react with the groundwater to make it very alkaline. This is a design feature, as very alkaline, 'rusty' conditions are expected to make most radioactive components of the ILW very insoluble. However, this alkaline water will react with the rock around the repository to form a 'chemically disturbed zone' (CDZ). Up until now, no studies have examined the chemical, physical and biological development of this CDZ and how this affects the mobility of radioactive contaminants from the GDF. We have chosen to study four long-lived radionuclides, the fission product technetium as well as uranium, neptunium and plutonium all of which will be present over the long timescales relevant to the CDZ. In this project, we will try and understand how the CDZ will evolve over thousands to millions of years, so we can predict the movement of radioactivity through it, and help assess the safety of the GDF. To do this, we need to study the chemical, physical and biological changes which occur as the CDZ develops, and the way in which these different factors interact with each other. We will use experiments to understand these processes and, based on these, we will develop computer models to predict what will happen in the future. We have divided our work programme into three parts: 1 Geosphere Evolution, where we will examine rock and mineral interactions, and how water flow within the rock is affected by chemical and microbiological changes caused by the water from the GDF; 2 Radionuclide Form, Reaction and Transport, where we will examine the chemical form and solubility of radionuclides, their interactions with microrganisms, and with rock surfaces, and the potential for microscopic particles to carry radioactivity; 3 Synthesis and Application, where we will bring all the experimental results together and design, develop and test our computer model to examine radionuclide transport in the CDZ. To ensure we link the different parts of the project effectively, we have identified two 'cross cutting themes' (CCTs) - (i) biogeochemical processes in the CDZ; and (ii) predictive modelling of the CDZ, which will tie all the different pieces of work together. Our work will provide improved understanding of the controls on contaminant mobility across the CDZ, improve confidence in the safety of geological disposal and hence assist the UK in the crucial task of disposing of radioactive wastes.
Publications
Bots P
(2014)
Formation of stable uranium(VI) colloidal nanoparticles in conditions relevant to radioactive waste disposal.
in Langmuir : the ACS journal of surfaces and colloids
Bots P
(2016)
Controls on the Fate and Speciation of Np(V) During Iron (Oxyhydr)oxide Crystallization.
in Environmental science & technology
Bower WR
(2016)
Characterising legacy spent nuclear fuel pond materials using microfocus X-ray absorption spectroscopy.
in Journal of hazardous materials
Brookshaw DR
(2015)
Redox Interactions of Tc(VII), U(VI), and Np(V) with Microbially Reduced Biotite and Chlorite.
in Environmental science & technology
Marshall T
(2018)
Uranium fate during crystallization of magnetite from ferrihydrite in conditions relevant to the disposal of radioactive waste
in Mineralogical Magazine
Marshall TA
(2014)
Incorporation and retention of 99-Tc(IV) in magnetite under high pH conditions.
in Environmental science & technology
Marshall TA
(2014)
Incorporation of Uranium into Hematite during crystallization from ferrihydrite.
in Environmental science & technology
Masters-Waage NK
(2017)
Impacts of Repeated Redox Cycling on Technetium Mobility in the Environment.
in Environmental science & technology
Moyce E
(2014)
Rock alteration in alkaline cement waters over 15 years and its relevance to the geological disposal of nuclear waste
in Applied Geochemistry
Smith K
(2015)
U(VI) behaviour in hyperalkaline calcite systems
in Geochimica et Cosmochimica Acta
Smith K
(2018)
Np(V) sorption and solubility in high pH calcite systems
in Chemical Geology
Description | We have learned important information about how radionuclides will behave as they emerge from the insdie of a GDF as in breaks down in 10's to 100's of thousands of years time. This information informs modelling the transport of these radionuclides and thus whether they are likely to interact adversely with earth systems such as groundwater. Further in the course of the grant we have dveloped a small radiochemical laboratory at Diamond to enable a wider range of active sample experiemnts to occur at the synchrotron. |
Exploitation Route | the results of the interactions of RN with other parts of the GDF background will be input to the NDA safety case for a GDF |
Sectors | Energy Environment |
Description | The findings are being used by RWM Ltd to inform various parts of their safety case for a GDF for intermediate level nuclear waste. Further NNL Ltd have used some of the XAS structural dat to inform their models for radionuclide transport . A report was written for RWM Ltd which is available on their website Summary of the BIGRAD project and its implications for a geological disposal facility |
First Year Of Impact | 2014 |
Sector | Energy |
Impact Types | Societal |
Description | An active materials laboratory for the UK synchrotron with associated equipment |
Amount | £3,986,000 (GBP) |
Funding ID | EP/T013796/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 11/2019 |
End | 03/2023 |
Description | Compositional and Structural Evolution of Plutonium Dioxide: Underpinning Future Decisions |
Amount | £13,785 (GBP) |
Funding ID | EP/T013796/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 05/2020 |
End | 05/2024 |
Description | Env-rad-net 2 STFC Network |
Organisation | University of Manchester |
Department | Faculty of Medical and Human Sciences |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Particpating in STFC funded env rad net mini project , which developed from initial Bigrad and Lorise activities. Aiming to develop methods to look at actinide containing particles on I18 and Iin particualr i14 beamline, notably from Fukashima environment. |
Collaborator Contribution | they are obtainign the samples from Japan through their collaboratiors, then both parties will collaborate on developing sample preparation mounting methods and in recording data at the synchrotron and it subsequent analysis |
Impact | no output yet, collaboration began september 2016 |
Start Year | 2016 |
Description | Cafe Scientifique talk |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | Talk at Cafe Scientifique in Salisbury , where I highlighted BIGRAD research at Diamond November 6 2012. Ed Rial also from Diamodn talked about how the synchrotron worked and I talked about BIGRAD research done there. Some members of the audience made plans to visit Diamond during one of its open days |
Year(s) Of Engagement Activity | 2012 |
Description | Diamond Light Source and how electrons produce photons that excite electrons that produce photons help probe materials relevant to the safe long term storage of nuclear waste |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Undergraduate students |
Results and Impact | Research Seminar to Chmistry undergraduates and masters students at UCLAN Two studnets applied for and one obtaiend a summer internship at Diamond. |
Year(s) Of Engagement Activity | 2014 |
Description | GeoRepNEt meeting (BGS) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | 40 people attended the Geo-Rep-Net/RATE meeting at BGS discussed variuos future SR expts with potential new collaborators |
Year(s) Of Engagement Activity | 2014 |
URL | http://www.astrobiology.ac.uk/events/georepnet-meeting |
Description | Seminar at University of manchester |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Postgraduate students |
Results and Impact | I gave a research seminar in the Dalton series organised at the University of Manchester to about 40 members of the chmistry and Seaes schools |
Year(s) Of Engagement Activity | 2014 |