About the Project
This project will develop the physical vapour deposition (PVD) route to produce coatings with improved mechanical stability and high temperature oxidation resistance, suitable for use as accident tolerant fuel coatings in light water reactors.
Aims and objectives
The 2011 Fukushima Daiichi accident highlighted the vulnerabilities of current nuclear fuel designs under severe accident conditions. A focus on loss of coolant accident (LOCA) scenarios has prompted international research to re-engineer the claddings, which contain the fuel, with the addition of a thin external coating in order for them to withstand higher temperatures and more severely oxidising conditions. New solutions for current LWRs are referred to as accident tolerant fuels (ATF). This research will be focused on the production of coated zirconium alloy fuel cladding material via the physical vapour deposition (PVD) process of magnetron sputtering. Magnetron sputtering is a well-established reliable and versatile method of applying coatings to surfaces, which is saleable from a lab-based system to a large throughput industrial processing. We will assess the benefits and vulnerabilities of the coatings, taking into account mechanical, physical and thermal properties of materials used as a potential surface coating for ATFs. Coatings produced will provide increased oxidation resistance coupled with resistance to mechanical damage, such as grid-to-rod fretting. Thus, the aim of this project is to investigate coating materials in order to develop an understanding of the effect of normal and LOCA conditions on the coating and coating/substrate interface, to produce a mechanically stable oxidation resistant ATF coating.
We will initially investigate a range of metallic coatings deposited via magnetron sputtering onto nuclear fuel cladding. The tribological behaviour of these coated fuel claddings will be assessed through a variety of mechanical tests to verify the reliability of the coating. Deformation of the coating and fretting wear will be investigated to assess coating compatibility in normal and LOCA operating conditions. The influence of artificially created defects, to mimic those experienced in operation, will also be investigated. The critical heat flux (CHF) is an important aspect of thermal hydraulic performance for any ATF coating. Changes in critical heat flux properties will have an impact on the progression of accident events and safety of the reactor. Therefore, changes in the pool boiling heat transfer will be investigated and compared to the existing Zr alloy. Experiments will involve analysis of the surface wettability, including measurements of contact angle and surface roughness. It is important that the normal behaviour of the cladding coating is not negatively impacted upon above the critical heat flux. This work will help to understand any potential detrimental changes to the normal operation with the addition of a coating to the existing Zr alloy cladding, to produce an optimal oxidation resistant, mechanically stable ATF coating.
Working alongside an experienced post doctoral researcher, this project will support a larger ATF project within the Advanced Materials and Surface Engineering Research Centre and will expand our portfolio of techniques and applications. The centre is well equipped with deposition and characterization facilities and has the expertise to design and modify equipment as required. The supervisory team have national and international industrial and academic collaborators in this field that are willing to contribute materials or test devices, and they will be brought in to support this project.
Specific requirements of the project
The candidate is required to have a background in engineering or a related scientific discipline and a keen interest in material science. Experience of thin film deposition (PVD) and characterisation (e.g. SEM, EDX, XRD, Raman) techniques will also be a distinct advantage. The candidate will need to demonstrate adaptability due to the multi-disciplinary nature of the work, and the capacity to carry out experimental work safely, and with precision. An ability to work as part of a diverse team, to meet deadlines and produce reports and presentations of a high standard to a range of audiences is essential. Applicants will require initiative, self-motivation, good communication skills, and the ability to critically evaluate their work. A willingness and ability to travel is an advantage, as the project may involve a short period of work at collaborating groups. As a consequence of this and due to the nature of this role, this vacancy is open to individuals who hold Security Clearance or have the ability to obtain Security Clearance to the level of BPSS.
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