Understanding Radioactive 'Hot' Particle Evolution in the Environment

Lead Research Organisation: University of Manchester
Department Name: Chemistry

Abstract

Whilst radioactivity has always been present in the environment, industrial and military use of nuclear materials over the past 70 years has led to numerous deliberate and accidental releases of radioactive materials. The impact of these materials on humans and wider ecosystems is controlled by the behaviour of the radionuclides in the environment. In turn, radionuclide behaviour and resultant bioavailability is dictated by their concentration and chemical form.

Radioactive 'hot' particles are often an important part of releases to the environment and thus they are commonly found at nuclear sites (e.g. Sellafield) or in areas impacted by deliberate releases (e.g. Ravenglass and Eskmeals, UK) or accidents (e.g. Chernobyl and Fukushima). After release, particle-bound radionuclides have been shown to behave very differently in the environment when compared with homogeneously dispersed contamination. However, there is a distinct lack of knowledge about the composition of, and chemical form of radionuclides in hot particles, or of the processes that control their longer-term stability, fate and impact, particularly at the molecular scale. This leaves significant gaps in our conceptual models of radionuclide environmental behaviour, making it difficult to facilitate robust, long-term predictions of radionuclide transport and fate. Ultimately, the impact of these uncertainties is profound: a lack of confidence in our ability to predict radionuclide behaviour in the environment impacts on the public perception of priority issues, for example, the geological disposal of nuclear waste and the implementation of new nuclear build. As a result, better quantification and understanding of the short- to long-term behaviour and potential impacts of hot particles in the environment is crucial.

Reflecting the above, we will use a range of laboratory experiments and field samples combined with state-of-the-art characterisation tools, to develop a clear understanding of hot particle evolution in the environment over timescales ranging from months to decades. The majority of our experimental work will focus on uranium-rich hot particles due to their prevalence in the environment, and we will alter these under a range of environmental conditions in flowing columns, for periods of > 1 year. Throughout, we will monitor changes in solution chemistry; further, we will use a range of synchrotron, mass spectrometry, and electron microscopy techniques to assess changes over time in particle structure, chemistry, and isotopic composition, as well as characterising the formation of any secondary phases. Complementary to our column experiments, and in an effort to understand longer timescale reactions (years to decades) and assess processes across a wider range of particle types, we will use the same techniques to characterise particles from contaminated field samples (e.g. from the Sellafield area and Eskmeals firing range).

The information from this work will lead to a much-improved conceptual model of radionuclide behaviour when hot particles are present in the environment. Further, by working with a range of key stakeholders (e.g. EA, DSTL), we can use this knowledge to predict radiological risk at contaminated sites better and inform land management / monitoring practices.

Planned Impact

The risk associated with nuclear material use always presents a major concern. Whether or not such perceptions are justified, they influence the public and decision-makers very heavily. Moreover, there are major uncertainties associated with radioactivity and the environment (especially radioactive 'hot' particles) and this may lead to a very conservative approach to risk. In turn, this may lead to incorrect estimates of doses and impacts, potentially leading to inappropriate decison making and excessive costs for little benefit. A proportionate understanding of risk in any nuclear programme is therefore essential for public acceptance, political support and proper cost-detriment analysis. Ultimately, the behaviour of radionuclides in the biosphere dictates the radiological risk they represent, and the proposed study of 'hot' particles will substantially improve our understanding of radionuclide behaviour in the environment, and therefore any associated risk assessments.

We have identified three main stakeholder groups who will benefit from this project; namely, Industry/Military, Regulators, and the UK National Security community (see letters of support). For Industry/Defence, several NDA Site Licence Companies (SLCs) and the MOD (or their contractors) have operational responsibility for land that is contaminated with hot particles. Our research findings will allow these stakeholders to make more informed management and remediation decisions regarding this existing legacy whilst also increasing preparedness for any future events (e.g. very severe reactor accidents). For Regulators (e.g. EA), our findings will permit better assessment of risk, across a range of timescales, thus facilitating more efficient regulation of nuclear sites. In the security area, as noted in the proposal, our research has a number of potential spin-offs in nuclear forensics (e.g. better identification of illicit nuclear materials brought into the UK). To ensure knowledge transfer to these stakeholder groups, we will engage with representatives of the EA, DSTL, AWE, and Sellafield Ltd., holding regular 'stakeholder' meetings where we report progress. As identified in the 'Pathways to Impact' (PTI) document, our representative stakeholders will then be able to disseminate this knowledge to others in their field (both nationally, and internationally). Finally, during month 30 of the project, we will hold a workshop with stakeholders to exploration potential continuation of this work and identify elements suitable for deployment.

Several other stakeholder groups may also benefit from our research findings. These include Government, Non-Governmental Organisations (NGOs), and the Wider Public. For Government and NGOs, knowledge transfer will mainly be facilitated through investigator participation in advisory bodies and learned societies (e.g. Committee for Radioactive Waste Management and Nuclear Innovation Research Advisory Board; Cabinet Office Science Advisory Committee via Livens; RSC and STFC Env-Rad-Net via Law; RCUK Energy Strategic Advisory Committee & MinSoc via Morris). To ensure engagement with the wider public, the team will participate across a range of outreach activities organised at The University of Manchester (identified in the PTI document).
 
Description Diamond Light Source Beamtime I18
Amount £16,000 (GBP)
Organisation Diamond Light Source 
Sector Academic/University
Country United Kingdom
Start 01/2017 
End 02/2017
 
Description Collaboration with AWE 
Organisation Atomic Weapons Establishment
Country United Kingdom 
Sector Private 
PI Contribution AWE directly support the project PDRA with analysis support. AWE have also co-sponsored a EPSRC Next Gen Nuclear DTC student that is now associated with the NERC grant.
Collaborator Contribution Studentship co-funding Analysis and sample support Professional advice (analysis for nuclear forensics)
Impact None as yet
Start Year 2016
 
Description Collaboration with Clemson University 
Organisation Clemson University
Department College of Engineering, Computing and Applied Sciences
Country United States 
Sector Academic/University 
PI Contribution We are conducting field experiments with Clemson University using the Savannah River Test bed facility to replicate our laboratory experiments at UoM that address environmental aging of uranic materials.
Collaborator Contribution Full access to field kit, personnel, and analysis
Impact None as yet
Start Year 2017
 
Description Collaboration with IRS Hannover 
Organisation Gottfried Wilhelm Leibniz Universität Hannover
Department Institute for Radio-ecology and Radiation Protection
Country Germany 
Sector Academic/University 
PI Contribution 2 x weeks of TOF-SIMS analysis of uranic samples at IRS Hannover, samples and PDRA / PhD support
Collaborator Contribution 2 x weeks of TOF-SIMS analysis of uranic samples at IRS Hannover, full technical support (3 x staff members of IRS)
Impact None as yet
Start Year 2016
 
Description LLNL collaboration 
Organisation Lawrence Livermore National Laboratory
Country United States 
Sector Public 
PI Contribution The project involves a collaboration with LLNL scientists to permit measurement of trace actinide in environmental samples.
Collaborator Contribution Measurement facility use and scientific advice
Impact None as yet
Start Year 2016
 
Description University of Manchester Experiments at the Soleil Synchrotron 
Organisation SOLEIL Synchrotron
Country France 
Sector Public 
PI Contribution Experiments were conducted on the Soleil Synchrotron MARS station to look at Tc, U, and Np co-ordination chemistry in a range of environmental samples.
Collaborator Contribution Facilitating measurements
Impact None as yet
Start Year 2016
 
Description Blue Dot Science Festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Environmental Radioactivity knowledge transfer as part of wider activities at the blue dot festival
Year(s) Of Engagement Activity 2016
 
Description Bluedot 2017 - Environmental Radioactivity 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Bluedot festival 2017 - Environmental radioactivity interactive display
Year(s) Of Engagement Activity 2017