Effect of high temperatures on cement backfill (NRVB) – Improving the safety case for deep geological disposal of radioactive waste.

University of Strathclyde

Department of Civil & Environmental Engineering

Project Description

Nuclear energy provides almost a fifth of the UK’s electricity, generating waste that needs to be managed for safe, long term storage. While most of this waste comes from the generation of electricity, it is also a by-product of many medical and industrial processes, research and defense activities that make use of radioactivity and radioactive materials. In a Geological Disposal Facility (GDF), higher-activity waste is stored hundreds of metres deep underground and GDF is internationally recognised as the safest long-term solution for this type of waste. This project focuses on understanding the long term chemical alteration and stability of a cement (NRVB) backfill material used in GDF, at the temperatures reached in the facility. This is important to improving and developing the safety case for deep geological disposal of radioactive waste. The information available on performance of NRVB under sustained exposure to elevated temperatures above 100 oC is very limited and deals largely with mechanical and thermal properties. The aim of this project is to understand the mineralogy and permeability evolution of hydrothermally cured NRVB at T=100-150 oC from 1 day to 1 year. Nanoparticulate calcium (aluminium) silicate hydrates (C-S-H/C-A-S-H), the primary hydration products of NRVB cement, can convert to more crystalline phases such as tobermorite, hillebrandite and afwillite during heating, which involves crystallographic restructuring, altering the micro-structure and affecting fluid flow paths. While some experimental studies exist on hydrothermally cured oilwell cements, the extent and implications of these recrystallisation/restructuring processes are largely unknown/unexplored for NRVB. The results from this project will aid further (future) work on radionuclide retention and reactive transport in NRVB, which requires a thorough understanding of mineralogy (and porosity/permeability) to support numerical/predictive models on radionuclide retention. Funded by Radioactive Waste Management, this project will directly inform on improving and developing the safety case for deep geological disposal of radioactive waste.

The successful candidate will be trained in and use techniques such as micro-(X-ray diffraction), electron probe micro-analysis, X-ray computed tomography and access national facilities such as Diamond Light Source, to determine how mineralogy, micro-strain, porosity and permeability of NRVB alter hydrothermally. The candidate has a unique opportunity to gain some industrial experience at Radioactive Waste Management (Oxfordshire) to understand their working environment first hand and make an impact on an important problem, while learning high-level and cutting-edge scientific techniques at Strathclyde. The student will be based in the Faculty of Engineering, one of the largest and most successful engineering faculties in the UK, and the largest in Scotland. The student will be supervised by an interdisciplinary team, including Drs Andrea Hamilton, Pieter Bots and Kate Dobson in Civil and Environmental Engineering (CEE) and Dr Paul Edwards in the Physics Department.

Funding Information

This is a fully funded 4 year PhD studentship, covering tuition fees and an annual tax-free stipend for 4 years at the standard UK research rate (£15,667 in 2021/22). A generous allowance is available for instrument access/conference attendance. The applicant is required to start by October 2021.
Available to students from the United Kingdom or the European Union (with settled or pre-settled status). Outstanding applicants that do not meet the above eligibility criteria may be eligible for full fees and a partial stipend, please contact Dr Hamilton.

Eligibility Requirements

We are looking for a highly motivated person to undertake multi-disciplinary research. Applicants should have an excellent undergraduate degree (MSc/MEng/BSc/BEng) in Chemistry/Chemical Engineering/Materials, Science/Physics, or related subjects, and be comfortable working in chemistry and engineering laboratories. Any previous experience using Matlab or similar is advantageous but not a pre-requisite. This is 1 of 2 studentships funded by RWM on long term cement behavior at Strathclyde University. Both studentships have to begin by October 2021 and provide an opportunity for collaborative working between the 2 successful applicants.

Application Process

Contact Dr Andrea Hamilton in the first instance ([email protected]) and as soon as possible, indicating your motivation to apply, your CV and outline any experience you have working in a laboratory.

To apply for this PhD, please email andrea.hamilton@strath.ac.uk.

Before sending your email, please double check you have followed all guidelines in this listing and have included a reference number if asked to do so.