Object kinetic Monte Carlo model for neutron and ion irradiation in tungsten: Impact of transmutation and carbon impurities

The influence of carbon impurities on the formation of loops in tungsten irradiated with self-ions

“…For clarity, the left panel was thus plotted in arbitrary units. In our previous work [10], we studied the mechanism of formation of TEM-visible loops (≥ 2 nm in size) during 2 MeV self-ion irradiation experiments, in the range of 300°C to 750°C. The conclusion stemming from our OKMC model was that these loops are, for the most, directly created during the primary damage of irradiation.…”

“…Considering that the plasma facing components will be made of commercially pure tungsten, the presence of impurities such as carbon belongs to the last item. Due to strong interaction of carbon with vacancies and dislocations [9,10], even small traces of carbon can have strong impact on the resulting irradiation induce microstructure.…”

“…Physically-based modeling [11,12] can help to rationalize the complicated process of the irradiation damage accumulation and directly extrapolate its prediction to service conditions in term of neutron fluence and spectrum, irradiation temperature and its transients, dose rate, nuclear transmutation resulting to the formation of rhenium and osmium, etc. In recent works [9,10], we have proposed a complete object kinetic Monte Carlo (OKMC) model that takes all these factors into account. The model was developed, parameterized, and validated covering a wide temperature range (400-1000°C) and using a variety of the experimental conditions, namely: 2-MeV self-ions [13,14], 18-MeV self-ions [15] and JOYO material test reactor irradiation [16].…”

Kinetic Monte Carlo Simulations of Irradiation Effects

“…For more simple alloys such as W-Re, or Fe-Cr, AKMC based on a large DFT data base, has really helped in unveiling mechanisms and explain experimental observations. IV-3 Typical damage accumulation / microstructure evolution: impact of dose, temperature, impurities … Many KMC studies has also been dedicated to characterize damage accumulation in various materials to model specific experiments such as ion implantation in Si for instance (Hobler and Otto 2003) or to investigate the impact of various parameters: the irradiation technique (ions versus neutrons , ions versus protons (Fluss et al 2004), continuous versus pulsed (Perlado et al 2003)), the neutron spectrum (Soneda et al 2003) (Choi and Joo 2013) (Figure 8), the dose, and dose-rate (Soneda et al 2003) (Chiapetto et al 2016a), the temperature (Soneda et al 2003) (Arévalo et al 2007) (Chiapetto et al 2016a) (Castin et al 2018), impurities or solute atoms (Alonso et al 2000) (Gámez et al 2007) (Castin et al 2018), the effect of annealing (Caturla et al 2000b) (Fluss et al 2004) or to compare materials (Caturla et al 2000a). The irradiation is typically modeled using cascade databases obtained either through MD (Perlado et al 1998) (Caturla et al 2000a) (Caturla et al 2000b) (Wirth et al 2001) (Marian et al 2001) (Arévalo et al 2007) (Chiapetto et al 2016a) (Warrier et al 2016) (Castin et al 2018) or the BCA method (Hobler and Otto 2003) (Otto et al 2005) (Hobler et al 2005) (Becquart et al 2006) (Valles et al 2015)…”

Recent advances in characterising irradiation damage in tungsten for fusion power

“…Using a combination of this approach and electronic structure calculations, it is possible to deduce the nature of the defect (vacancy or self-interstitial), morphology and its depth-resolved distribution in the implanted layer [48,70]. Electronic structure or first principle calculations provide information about the atomistic level, such as that of interaction between radiation defects and solute atoms [54,55,[71][72][73][74]. To account for different length scales and time scales, several different complementary atomistic modelling techniques such as Density Functional Theory (DFT) calculations, Molecular Dynamics (MD), Kinetic Monte Carlo (KMC), Mean Field Rate Theory (MFRT) and Dislocation Dynamics (DD) are used [75].…”