Radionuclide fate in on-site disposal of activation product contaminated wastes

A fully-funded PhD studentship is available to a chemistry or closely related disciplines graduate with interests in environmental chemistry and radioactive waste challenges. Disposal of nuclear legacy waste and the decommissioning of nuclear reactors is one of the biggest scientific and engineering challenges of the 21^st Century.

Decommissioning wastes from nuclear reactors will be significant in volume, and will include lightly contaminated radioactive contaminants including isotopes from neutron activation of the infrastructure around the reactor core (e.g. ⁶⁰Co, Ni-isotopes and ¹⁵²Eu). Management of these materials is challenging and on site disposal of these lightly contaminated materials (e.g. concrete and contaminated land) is being actively considered. Here, on-site disposal of radioactively contaminated materials from nuclear sites may be optimal for management of lightly contaminated concrete, rebar (and its corrosion products) and radioactively contaminated land (RCL) may be the best available option. Management of these materials is challenging in terms of traditional dig and dump approaches, and examples of on-site disposal under consideration include leaving lightly contaminated concrete structures and RCL in situ or using suitable lightly contaminated waste (e.g. crushed concrete), as void backfill. Any safety case for on-site disposal needs to reduce uncertainties and predict contaminant behaviour over relevant timeframes in these complex interface environments. To develop the safety case for these approaches, an underpinned understanding of radionuclide behaviour in these complex environments in terms of their initial speciation and potential contaminant transport as the site evolves is required.

In this project the student will focus on the environmental behaviour of key neutron activation contaminants including Ni-isotopes, ⁶⁰Co and ¹⁵²Eu, which are significant at former nuclear reactor sites. Using non-active isotopes, and select experiments with radionuclides, we will explore contaminant speciation in representative cementitious materials (e.g. bioshield / concrete) with and without iron oxides (from rebar) and under evolving conditions exploring ageing effects and saline intrusion associated with sea level rise. Finally we will explore the impacts of key biogeochemical processes on contaminant speciation and fate to build a picture of contaminant behaviour in on-site disposal scenarios.

This project will involve fundamental, interdisciplinary research combining radiochemistry, environmental radioactivity and mineralogy with cutting edge techniques in a state of art facility. The research project will be carried out in the University of Manchester’s RADER lab facility (https://www.ees.manchester.ac.uk/wrc/research/facilities/rader/) and will include solid- and solution-phase characterisation techniques. Throughout the study, the successful applicant will investigate the chemical speciation (local bonding environment) of neutron activation contaminants using X-ray absorption spectroscopic techniques to underpin the behaviour of these elements giving a fundamental understanding of their (bio)geochemistry.

The successful applicant will join a welcoming, vibrant group of 20+ researchers examining environmental chemistry and radioactivity research topics and receive training in a wide range of experimental techniques and methodologies including the handling of radioactive materials and X-ray absorption spectroscopy. They will also have the opportunity to present their research results to their nuclear industry supervisor, and at national and international research conferences. The project benefits from established links to the UK nuclear industry (e.g. co-funder Nuclear Decommissioning Authority – NDA) and state of the art facilities in the University of Manchester’s Department of Earth and Environmental Science RADER labs. Furthermore, we have established links to radionuclide speciation via the Diamond Light Source. The student will benefit from co-funding through the SATURN CDT with a tailored training program, the success of which has been demonstrated by two-thirds of graduates from previous nuclear CDTs going on to work in the nuclear sector, and 90% taking up technical roles.

Applicants should have, or expect to achieve, at least a 2.1 honours degree or a master’s (or equivalent) in a relevant science or engineering related discipline. This project would suit an applicant with a background in Chemistry, Environmental Chemistry, Geosciences or a closely related discipline, willing to apply their skills to radioactive waste disposal. A Master’s degree in a relevant subject, and/or experience in handling and analysis of environmental samples containing radionuclides are desirable but not essential as all necessary training will be given.

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