Elucidation of unusual nano-effects on dissolution, aggregation and denaturation processes of alpha particles generated by fuel debris retrieval

Lead Research Organisation: UNIVERSITY COLLEGE LONDON
Department Name: Chemical Engineering

Abstract

The safe retrieval and storage of nuclear fuel debris, such as that generated by the Fukushima-Daiichi nuclear power plant accident 10 years ago, requires an understanding of the behaviour of these debris while being stored and processed. Bulk scale studies have been conducted which have yielded understanding of the characteristics of these debris at the larger scales. However, it has been noted that the processing of these debris generates micro- and nano-scale particles, particularly in the 1 to 100 nm scales. These particles are in solution and may be present in aerosols generated by the processing such as cutting with mechanical or laser means. Importantly, the particles at these scales behave differently than particles at larger scales. This difference in behaviour must be understood to be able to predict their behaviour while being processed.
This project brings together experimental expertise, both in the UK and Japan, as well as expertise in the development and use of mathematical modelling to develop the experimental and mathematical tools necessary to ensure safe processing of the debris. The experimental expertise includes characterisation capabilities for structure and surface properties of the particles and for the dynamic behaviour of the particles in solutions in microfluidic channels, including dissolution, denaturation, and aggregation/agglomeration. The resources and expertise of the labs at UCL and Tokyo Institute of Technology are complementary. The mathematical expertise at UCL is also well aligned with the experimental capabilities, demonstrated through previous successful collaborative projects.

Publications

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Angeli P (2024) Intensified liquid-liquid extractions by continuous flows in small channels in Chemical Engineering and Processing - Process Intensification

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Pheasey C (2023) Intensified Nd extraction in small channels for NdFeB magnet recycling in Separation and Purification Technology

 
Description Large amounts of nuclear fuel debris generated from the Fukushima Daiichi Nuclear accident pose unpredicted but severe environmental and ecological challenges. Understanding the denaturation behaviour of nanoscale nuclear fuel particles, such as plutonium oxide (PuO2), during retrieval and cutting processes is crucial for ensuring safe handling and storage. Cerium dioxide (CeO2) is widely used as a non-radioactive surrogate for PuO2 due to its similar crystal structure and physicochemical properties. Investigating the aggregation and dissolution behaviour of CeO2 nanoparticles (NPs) in hydrogen peroxide (H2O2) provides valuable insights into the potential denaturation mechanisms of PuO2 NPs during nuclear power plant decommissioning. In this study, H2O2 was employed as the primary medium to simulate conditions during nuclear power plants decommissioning. Our findings reveal that CeO2 NPs undergo significant aggregation and slow dissolution across a range of H2O2 concentrations with aggregation increasing as H2O2 concentration decreases.
Cerium gradually dissolved through hydrolysis of the complexes, with smaller particles exhibiting faster and higher dissolution compared to larger ones. Interestingly, the existence of ZrO2 NPs significantly inhibited the redox reaction, thereby reducing both the aggregation and dissolution of CeO2 NPs.
The aggregation and dissolution behaviour were found to be different when experiments were carried our in flow channels.
These findings have substantial environmental implications, particularly in understanding the stability and dissolution behaviour of CeO2 NPs in natural water systems and wastewater treatment processes. Furthermore, this study provides foundational insights into the denaturation of nuclear debris particles, supporting their safe and sustainable management.
Exploitation Route The current findings have substantial environmental implications, particularly in understanding the stability and dissolution behaviour of CeO2 NPs in natural water systems and wastewater treatment processes. Furthermore, this study provides foundational insights into the denaturation of nuclear debris particles, supporting their safe and sustainable management.
Sectors Chemicals

Energy

Environment

 
Description Intensified high throughput extraction of iron in small channels
Amount £28,400 (GBP)
Funding ID 10117304 
Organisation Innovate UK 
Sector Public
Country United Kingdom
Start 05/2024 
End 08/2024