UKAEA Journals

Showing 1 - 10 of 19 Journals Results
2021
UKAEA-CCFE-PR(21)56

Hydrogen isotopes are retained in materials for fusion power applications, changing both hydrogen embrittlement and tritium inventory as the microstructure undergoes irradiation damage. But modelling of the highly damaged regime – over 0.1 displacements per atom (dpa) – where asymptotic saturation is observed, is difficult because a highly dama…

Preprint
2021
UKAEA-CCFE-PR(21)33

Prediction of material performance in fusion reactor environments relies on computational modelling, and will continue to do so until the first generation of fusion power plants come on line and allow long-term behaviour to be observed. In the meantime, the mode…

Preprint Published
The published version of this paper is currently under embargo and will be available on 08/06/2023
2021
UKAEA-CCFE-PR(21)01

The ability of a body-centered cubic metal to deform plastically is limited by the thermally activated glide motion of screw dislocations, which are line defects with a mobility exhibiting complex dependence on temperature, stress, and dislocation segment length. We derive an analytical expression for the velocity of dislocation glide, based on a s…

Preprint
2020
UKAEA-CCFE-PR(20)113

Combining spatially resolved X-ray Laue diffraction with atomic-scale simulations, we observe how ion-irradiated tungsten undergoes a series of non-linear structural transformations with increasing irradiation exposure. Nanoscale defect-induced deformations accumulating above 0.02 displacements per atom (dpa) lead to highly fluctuating strains at ~…

Preprint Published
2020
UKAEA-CCFE-PR(20)108

We performed ab initio density functional theory simulations of 1/2{111} interstitial dislocation loops, closed and open vacancy loops, {100} interstitial loops and voids in tungsten, using simulation cells involving from 2000 to 2700 atoms. The size of the loops transcends the microscopic scale and reaches the mesoscopic scale where as…

Preprint Published
2020
UKAEA-CCFE-PR(20)72

Self-ion bombardment of pure tungsten with ion energies of 2 MeV is used to mimic the defects created by neutrons in a fusion reactor. Electron microscopy is used to characterize the microstructure of samples. Thermal Desorption Spectrometry (TDS) is performed on deuterium implanted samples in order to estimate deuterium inventory as function of…

Preprint
2019
UKAEA-CCFE-PR(20)06

We present a morphological analysis of atom probe data of nanoscale microstructural features, using methods developed by the astrophysics community to describe the shape of superclusters of galaxies. We describe second-phase regions using Minkowski functionals, representing the regions’ volume, surface area, mean curvature and Euler characteristi…

Preprint Purchase
2019
UKAEA-CCFE-PR(19)44

The low energy structures of irradiation-induced defects have been studied in detail, as these determine the available modes by which a defect can diffuse or relax. As a result, there are many studies concerning the relative energies of possible defect structures, and empirical potentials are commonly fitted to or evaluated with respect to these en…

Preprint Published
2019
UKAEA-CCFE-PR(19)41

A new facility to study the interaction of hydrogen isotopes with nuclear fusion relevant first wall materials, its retention and release, has been produced. The new facility allows implanting a range of gases into samples, including tritium. Accurate study of isotope effects, such as the isotopic exchange in damaged microstructure, has previously …

Preprint Published
2019
UKAEA-CCFE-PR(19)17

We describe the development of a new object kinetic Monte Carlo code where the elementary defect objects are off-lattice atomistic configurations. Atomic-level transitions are used to transform and translate objects, to split objects and to merge them together. This gradually constructs a database of atomic configurations- a set of relevant defect …

Preprint Published