Performance and Reliability of Metallic Materials for Nuclear Fission Power Generation

Lead Research Organisation: Loughborough University
Department Name: Mathematical Sciences

Abstract

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Publications

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Gai X (2015) Helium bubbles in bcc Fe and their interactions with irradiation in Journal of Nuclear Materials

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Gai X (2016) Inert gas bubbles in bcc Fe in Journal of Nuclear Materials

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Lazauskas T (2014) Influence of the prefactor to defect motion in a-Iron during long time scale simulations. in Journal of physics. Condensed matter : an Institute of Physics journal

 
Description The atomic configurations and formation energies of different He-vacancy complexes have been determined and their stability in the region of nearby collision cascades investigated. The results show that the optimal He to Fe vacancy ratio increases from about 1:1 for approximately 5 vacancies up to about 4:1 for 36 vacancies. Collision cascades initiated near the complex show that Fe vacancies produced by the cascades readily become part of the He-vacancy complexes. The energy barrier for an isolated He interstitial to diffuse was found to be 0.06 eV and He clusters containing up to 4 atoms are highly mobile. A 5 atom cluster can eject Fe interstitials and become pinned. These act as seed sites for subsequent He accumulation. Under irradiation, vacancies can also accumulate in the He clusters increasing their stability.
In the case of argon and xenon, the atoms prefer to be substitutional rather than interstitial and bubbles are much harder to form. The optimum gas to vacancy ratio is about 1:1 for Ar and 0.6:1 for Xe. The diffusion mechanisms for both Ar and Xe are similar with high energy barriers, typically > 1 eV.
Exploitation Route The findings can also be used in conjunction with experiment to predict typical bubble sizes in fission reactor structural materials. They can also be used to ascertain the lifetime these materials once the dose rates and temperatures are known.
The results can be used by experimentalists to verify the models. In addition similar techniques are now being used to model the formation of argon bubbles in the growth of CdTe thin films by magnetron sputtering for solar applications.
Sectors Energy

 
Description The methodologies developed for analysing He bubble formation in irradiated Fe have been applied to PuO2 by Birmingham university in conjunction with Sellafield (Helen Steele). This has led to an understanding of how the ageing process occurs and a paper is being prepared to publish these findings. This should lead to further impact regarding processes for the long term storage of special nuclear materials at Sellafield
First Year Of Impact 2022
Sector Energy
Impact Types Societal

 
Description member of the OECD structural materials modelling committee
Geographic Reach Multiple continents/international 
Policy Influence Type Participation in a guidance/advisory committee
URL https://www.oecd-nea.org/download/wpmm/SMM/
 
Title adaptive kinetic monte carlo method for long time scale analysis of defect motion in materials 
Description The techniques uses a combination of saddle point searching on n-dimensional surfaces and parallel computing to determine transition barriers and long time evolution of defects and impurities in solid state materials. In the glass project we identified PARSPLICE as an excellent methodology to investigate defects in glasses. 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? No  
Impact Although the a-KMC approach was developed over a number of years the current methodology lbo-akmc is under continual development 
 
Description MRS meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Participants in your research and patient groups
Results and Impact Talk sparked questions afterwards

Invited paper for a special edition of Journal of Nuclear Materials
Year(s) Of Engagement Activity 2011
 
Description extending time scales workshop dresden 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact about 60 participants attended the workshop and new techniques were implemented into atomistic codes as a result
Year(s) Of Engagement Activity 2010
URL http://www.mpipks-dresden.mpg.de/~bemod12/