Radiation damage of steels used in the nuclear industries

Research Group: 
Centre for Condensed Matter and Material Physics
Full-time Project: 
QM Scholarship
Project Description: 
Stainless steels are used throughout the nuclear power industry, from components of the nuclear reactors (fission or proposed fusion) through to the storage of high-level nuclear waste. Steels are subject to high levels of irradiation, including from alpha particles through to heavy-atom recoils. The effect of radiation is to damage the crystal structure, whether from forming a large number of small defects or by localised melting of the structure in the region of the irradiation. As a result of considerable efforts in developing methods and programs, and through utilising massive supercomputing facilities, we can now simulate the damage to crystal structures caused by radiation damage. We have, for example, studied radiation damage in ceramics being considered for long-term encapsulation of radioactive waste and damage caused in iron through neutron bombardment. We have consistently broken records for the largest complex materials studied for this sort of work. Our capability has now refined to the point whereby we can now go beyond pristine crystal structures to study radiation damage in materials with crystalline microstructures, particularly grain boundaries. Thus we are now poised to tackle the most important material, namely stainless steel, which is composed of a fine intergrowth of iron with iron carbide phases.

The project is to simulate radiation damage in realistic models of stainless steel using the molecular dynamics method, which is a form of virtual reality in that it simulates atomic movements within a large configuration of atoms based on equations of motion using realistic representations of the interatomic forces. The first stage in the project is to develop models of forces for the iron-carbon phases based on methods used for the pure iron phases. The second phase is to develop atomic models of stainless steel for many millions of atoms, based on the known crystal structures and guided by the microstructures observed by microscopy. We will produce both bulk phases and configurations with surfaces in order to study irradiation through radioactive decay and from external bombardment. The third phase, which will be the major part of the project, is to study the actual irradiation process and analysis the results of the simulations. The major outputs of this will be a new understanding of how radiation damages stainless steels, and the extent to which self-organisation of the structures is able to lead to some degree of healing of the atomic configuration. The damaged configurations will be analysed to correlation radiation damage with physical properties, with the aim to understand how radiation damage ultimately affects the strength of the material. We hope that we will be able to feed these results back into the nuclear industry, in what is quite a critical time in terms of whether we will see renewed reliance on nuclear power in the face of environmental concerns about energy production (such as the consequences of burning organic fuels).

The student will learn how to perform record-breaking atomistic simulations using the UK’s national supercomputing resources. This will involve understanding the basic simulation algorithms, together with understanding approaches to modelling the forces between atoms. It will also require engagement in the process associated with access to these resources, including writing proposals and reports on a regular basis and engagement with the UK materials simulation community. The project will require development of specific computer programs for generating the original atomic configurations and for data analysis, and the student will be trained in modern programming methods.

1. Electronic effects in high-energy radiation damage in iron. E Zarkadoula, SL Daraszewicz, DM Duffy, MA Seaton, IT Todorov, K Nordlund, MT Dove, and K Trachenko. Journal of Physics: Condensed Matter 26, 085401 (8 pp), 2014. http://iopscience.iop.org/0953-8984/26/8/085401/
2. High-energy radiation damage in zirconia: Modeling results. E Zarkadoula, R Devanathan,WJ Weber, MA Seaton, IT Todorov, K Nordlund, MT Dove, and K Trachenko, Journal of Applied Physics 115, 083507 (7 pp), 2014. http://scitation.aip.org/content/aip/journal/jap/115/8/10.1063/1.4866989
3. Structural changes in zirconolite under alpha-decay. HF Chappell, MT Dove, K Trachenko, REA McKnight, MA Carpenter, SAT Redfern. Journal of Physics: Condensed Matter 25, 055401 (6pp), 2013. http://iopscience.iop.org/0953-8984/25/5/055401/
4. The nature of high-energy radiation damage in iron. E Zarkadoula1, SL Daraszewicz, DM Duffy, MA Seaton, IT Todorov, K Nordlund, MT Dove and K Trachenko. Journal of Physics: Condensed Matter 25, 125402 (7pp), 2013. http://iopscience.iop.org/0953-8984/25/12/125402/
The student will need to be comfortable in using computers, and will be expected to learn some programming skills. He/she will also need to learn to engage with the consortium through whom we gain access to national supercomputing resources.
SPA Academics: 
Kostya Trachenko
Prof Martin Dove