From Processing to Simulated In-Reactor Performance of Zr Cladding.

Nuclear energy will play a critical role in the future of secure, affordable and low-carbon power generation. The UK is committed to a greenhouse emissions target of 80% of pre-1990 levels by 2050 and as part of this, between now and then, it is likely that the percentage of power generation via nuclear will have to increase by somewhere between two- and three-times.

The vast majority of nuclear power is generated by light water nuclear reactors. These use cladding made from various types of zirconium alloy to contain ('clad') nuclear fuel, creating a barrier between highly active fuel/fission products and the coolant. Zirconium is considered an ideal material for this purpose, as it has excellent corrosion resistance properties and a small neutron cross section, meaning that it has a low rate of neutron absorption. These properties make zirconium alloys fundamentally more suitable than many other materials in reactor conditions.

There is still much more to be learnt about the behaviour and durability of zirconium alloys, in order to enhance their performance and the efficiency of nuclear power generation. If we gain further understanding about how these materials behave in a nuclear reactor, we can more accurately predict the 'life' of the clad and even develop new, more sophisticated alloys - advancements which can minimise new nuclear waste production and further enhance fuel and reactor safety.

Zirconium alloy research is therefore at the heart of nuclear power generation and safety. Within this context, this project aims to develop increased understanding in the field of zirconium processing and its relationship to in-reactor performance. The UK-India Civil Nuclear Collaboration is an on-going initiative to promote cooperative research in the area of nuclear energy, and this Phase III project builds upon a highly successful project undertaken in Phase I. The previous collaboration, between the University of Manchester and the Bhabha Atomic Research Centre (BARC) in India, made significant developments in the understanding of zirconium alloys, through both experimental and modelling work. This work has already had direct relevance to, and application by, the nuclear industry.

This project aims to directly follow-on from this work, adopting a 'cradle-to-grave' approach intended to gain further understanding about the in-reactor performance of zirconium, including how the initial 'processing' of the material might impact on its properties. The proposed work will again be carried-out with partners at BARC, as well as at the Indira Gandhi Centre for Atomic Research (IGCAR).

Once new hypotheses about zirconium are developed, including potential new alloy compositions, these must be thoroughly tested in reactor conditions before real-world application. This is a costly and time-consuming process, with few test reactors available to researchers and the costs/experimental difficulties associated with working on radioactive material. Partly in response to this, nearly £30m has been invested into the development of the University of Manchester's Dalton Cumbrian Facility (DCF), designed to allow research on irradiated and activated materials.

DCF will enable the other key aspect of this project: the development of novel experimental set-ups (pioneered at the University of Michigan) at both DCF and IGCAR. These experiments will allow the investigation of material degradation during irradiation, mimicking the conditions experienced in reactors without producing radioactive samples, and so drive forward accurate, practical understanding of zirconium performance, enhancing efficient, safe nuclear power generation.

This project brings together outstanding capabilities and expertise from the UK (Manchester and Sheffield) and India (BARC and IGCAR), enabling a unique research programme that will have impact for the nuclear industry and research, as well as helping to develop new experimental techniques for the field.

The proposed project aims to further develop a very successful collaboration from Phase I of the UK-India Civil Nuclear Collaboration. The Phase I project has already had significant, measurable impact, including a number of highly relevant publications, presentation of results at the preeminent conference in the field of Zr research (ASTM's International Symposium on Zirconium in the Nuclear Industry), career progression for its researchers (including a Senior Lectureship at Swansea for Manchester PDRA, Dr Leo Prakash), and take-up by industry. Industry interest has resulted in official support for the new proposal by a number of companies, who have signed-up as project partners, and so will directly benefit from the work.

The proposed work aims to underpin the UK nuclear renaissance, through research in the field of radiation damage of nuclear materials. New nuclear build market value has been estimated at £600 billion and with appropriate Government investment, including development of a new generation of experts, UK companies could capture a significant global market share. Due to prevalent use in fuel assemblies, Zr alloy research is at the heart of nuclear power generation and safety, and the behaviour and durability of alloys is a crucial nuclear power cost-factor.

The UK has recently seen a spectacular rise in its capability with regard to Zr research and is now a world-leading player, already attracting substantial international funding from supply chain companies and reactor OEMs and vendors. Power plant operators, fuel manufacturers and the nuclear industry, as well as regulators, have all identified a critical and urgent need to improve understanding of materials processing parameters on clad material degradation, in support of optimising safe and efficient operation of nuclear power plants. The proposal aims to enhance understanding of Zr behaviour in reactor conditions, with an emphasis on relating material processing with materials performance. This will result in significant benefits for the economic, safety and environmental performance of light water reactors in the UK, India and globally (e.g. through the introduction of new, reduced-risk manufacturing processes).

A key aspect of this work is to drive new capability for in situ corrosion and creep testing during proton irradiation. Experimental set-ups first implemented at the Michigan Ion Beam Laboratory will be replicated at the Dalton Cumbrian Facility and at IGCAR's facilities in India. Such set-ups will enable new research in a range of areas, and provide an alternative to costly and difficult test reactor work. This is an urgent, widely identified need, allowing the undertaking of targeted experiments which will, for example, improve life predictions of nuclear components, as well as enable related and future work in this area. The development of the in situ set-ups would be directly disseminated to the nuclear community via a workshop planned as part of this proposal.

Experimental data produced by these set-ups will also be of high value for atomistic and other modelling efforts concerned with irradiation damage, irradiation-enhanced corrosion and creep, and so will have impact across a range of nuclear materials work currently being undertaken.

Critically, this programme represents investment in the education of a new generation of nuclear materials scientists. Besides engaging the project PDRAs in the field, it is anticipated that industry interest will enable additional PhD studentships. Work on Zr in the UK, and particularly at Manchester, has already been pivotal in developing young researchers in the field of nuclear materials, who have gone on to hold positions in academia and with a range of industrial partners. Through public engagement, particularly outreach activities, the results of the proposed work will also be conveyed to future nuclear materials students and researchers.