CMSP Webinar (Atomistic Simulation Seminar Series) 11 May at 11:00, Prof. Duc Nguyen-Manh

[CMSP Seminars Secretariat]

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Atomistic Simulation Webinar Series
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Zoom link to advance registration:

https://zoom.us/meeting/register/tJwkceyspzIoHteHurD9ZNF_8C5Yz0CPVHre



** * * Wednesday, 11 May 2022 at 11:00**CET* * **


Speaker:*Prof. Duc Nguyen-Manh *(United Kingdom Atomic Energy Authority)

Title:***Challenges and perspectives in predicting phase stability and 
radiation damages in plasma-facing materials for fusion-power plant 
application
*
Abstract:
“We say that we will put the sun into a box. The idea is pretty. The 
problem is, we don’t know how to make the box” (Pierre Gilles de Gennes).

  Nuclear fusion - the joining together of atomic nuclei of light 
elements such as the reaction between two hydrogen isotopes, deuterium 
(D) and Tritium (T) to form heavier helium atoms - is the process by 
which vast amounts of energy is produced in stars like our sun. If it 
can be harnessed on Earth it has the potential deliver a nearly 
unlimited and safe source of energy which does not produce the 
environmentally damaging CO2 emissions that are released by burning 
traditional fossil fuels. To achieve nuclear fusion in a machine on 
Earth, extraordinarily high temperatures of around 150 million degrees 
Celsius are needed, about 10 times higher than the temperature of the 
sun's core.  Most recently, the UK-based Joint European Torus (JET) 
laboratory in Culham, has made a breakthrough in the quest to develop 
practical energy fusion in producing 59 MJ of energy (more than double 
what was achieved in the 1997 test) but over only 5 seconds.

The major technological challenges of fusion energy are intimately 
linked with the availability of suitable materials capable of reliably 
withstanding the extremely severe operational conditions of fusion 
reactors. The energetic spectrum associated with the D-T fusion neutrons 
(14.1MeV compared to<2MeV on average for fission neutrons) releases 
significant amounts of hydrogen and helium as transmutation products 
that might lead to a degradation of materials after a few years of 
operation.  Structural materials development, together with research on 
functional materials capable of sustaining unprecedented power densities 
during plasma operation in a fusion reactor, have been the subject of 
decades of worldwide research efforts underpinning the present fusion 
materials research programme. Overcoming the lack of a fusion-relevant 
neutron source for materials testing is an essential pending step in 
fusion roadmaps.

At the same time, fundamental understanding of the transient materials 
changes due to fusion neutron loading pose scientific and predictive 
computational challenges that require the development of an integrated 
framework to support the design effort for future fusion power plants. 
In this talk, we highlight the recent advances in developing an 
integrated multi-scale modelling based on first-principles calculations 
to investigate phase stability under and microstructure evolution of 
plasma-facing material components such as reduced-activation 
ferritic/martensitic (RAFM) steels for the first wall and W&W alloys for 
the divertor [1-5]. More attention will be focusing on our recent 
development of constrained thermodynamic approach in predicting free 
energies of the various phases in the presence of radiation-induced 
defects (saturated vacancies, interstitials, and precipitates) with the 
final microstructure of combinations of phases giving the lowest free 
energy. The model has been successfully employed not only to understand 
the origin of microstructures decorated by transmutation products in 
neutron irradiated W [6-7] but also to predict new W-based based 
high-entropy alloys with outstanding radiation resistance [8].

[1] D. Nguyen-Manh et al., Phys. Rev. B, 73, 010201 (2006); PRB, 80, 
104440 (2009)
[2] D. Nguyen-Manh et al., Progress in Materials Science., 52, 255 (2007).
[3] D. Nguyen-Manh et al., J. Mater. Science, 47, 21 (2012)
[4] D. Nguyen-Manh et al., Annal of Nuclear Energy, 77, 246 (2015); 
NIMB, 352, 86 (2015)
[5] K. Arakawa et al., Nature Materials, 19, 508 (2020)
[6] D. Nguyen-Manh et al, Phys. Rev. Mater., 5, 065401 (2021)
[7] M. J. Lloyd et al., Materialia, 22, 101370 (2022)
[8] O. Et-Atwani et al., Science Advances, 5, eaav2002 (2019)

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