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PhD studentship: Resolving reaction mechanisms, kinetics and mass transport in radionuclide-loaded geopolymer cement wasteforms

Applications accepted all year round

Location: University of Sheffield

In the UK, over 150,000m of radioactive waste (enough to fill 60 Olympic size swimming pools) has been produced to date. Most of this radioactive waste needs conditioning, by either encapsulating it in cement, or another method, prevent release to the biosphere. Geopolymer cements are attractive for cementation of radioactive waste due to enhanced chemical resistance in aggressive environments, enhanced chemical tolerance to problematic wastes, higher fluidity of preparation leading to higher waste loadings, and cation-binding sites that provide enhanced capture of radioactive waste. Geopolymers have demonstrated lower leach rates of fission product surrogates than other encapsulant alternatives and this may be used to justify greater waste loading or disposal of boundary wastes to lower repository ratings. However, there is little information on what parameters of raw materials are critical to reliable application, under such conditions required on nuclear encapsulation plants.

This project aims to provides greater understanding of geopolymer reaction, setting and hardening, by investigating fundamental particle interactions, so that robust specifications can be developed, and geopolymer wasteform properties and performance can be predicted. The project also aims to assess mobility of fission products, and establish chemical durability and radioactive waste retention.

Specifically, it will:

  1. characterise geopolymer wasteform phase assemblage, micro- and nanostructure, and structure of the pore network
  2. investigate fundamental particle interactions so that robust specifications can be developed,
  3. determine radionuclide (e.g. 90Sr and 137Cs)-cement interactions and
  4. assess radionuclide retention. This will identify key interactions controlling phase evolution, structural evolution across micro, nano and atomic length scales, radionuclide-cement interactions mass transport mechanisms and leaching resistance, and physical and chemical stability in repository relevant conditions.

Based in the Departments of Chemical and Biological Engineering, and Materials Science and Engineering, the successful candidate will be joining a team of multidisciplinary researchers at The University of Sheffield to develop research and innovation for decarbonisation. The successful applicant will be a part of the GREEN CDT (see below), and join the Sustainable Materials at Sheffield and Cements@Sheffield research teams. They will also benefit from industrial supervision by the Encapsulant Integrated Research Team lead and deputy of the Intermediate Level Waste Packaging Development Centre of Expertise, Sellafield Ltd. They will benefit from being a member of a friendly and collegial group with world-leading expertise and facilities.

The Sustainable Materials at Sheffield group (in the Department of Chemical and Biological Engineering) and the Cements@Sheffield group (in the Department of Materials Science & Engineering) are world-leading research teams, located in highly-rated and very successful departments, building from over 100 years of history in cements research at Sheffield. We investigate interesting and important cements and related materials for applications in nuclear and infrastructure sectors, publish our work in the leading journals and conferences in the field, and take great pride in the fact that alumni have gone on to the highest levels of success in both academia and industry. Both the Department of Chemical and Biological Engineering and the Department of Materials Science & Engineering rank among the top in the UK, and have among the highest levels of research income.


The GREEN Centre for Doctoral Training (GREEN CDT) is a consortium of five universities: The University of Manchester, Lancaster University, The University of Leeds, The University of Liverpool and The University of Sheffield, which aims to train the next generation of expert nuclear scientists and engineers.

The four-year PhD programme invites students to attend taught courses (Year 1) in various subjects of nuclear technology followed by subject specific training (Year 1), then progress to the PhD-level research activities described in the Summary (Year 2-Year 4)

Published: May 5th, 2021
Posted in Funding Opportunities

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