Numerical study of the influence of tungsten recrystallization on the divertor component lifetime

Durif, A.; Richou, M.; Kermouche, Guillaume; Bergheau, Jean‐Michel

doi:10.1007/s10704-021-00568-1

Cited by 3 publications

(7 citation statements)

References 33 publications

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“…To better understand the damage process, this study aims at performing numerical simulations with representative WEST heat loading (quasi steady-state and disruptions) as inputs. Based on an user-defined numerical tool in ANSYS [5], the modeling performed in this paper allows to obtain: (i) the thermal gradient; (ii) the softening (recovery/recrystallization) gradient; and (iii) the stress and strain distributions taking into account the mechanical properties of tungsten (elastic-viscoplastic) and the softening phenomenon.…”

Section: Contextmentioning

confidence: 99%

“…• Brittle fracture, when stress (σ) exceeds the material yield stress (σ y ) below the tungsten Ductile to Brittle Transition Temperature (DBTT) [6]. In the upcoming simulations σ y is calculated based on linear interpolation of data obtained for a strain rate of 6 × 10 −1 /s in [5].…”

Section: Assumptionmentioning

confidence: 99%

“…Papers highlight that longitudinal macro-crack appeared at the center of the tungsten monoblock after few tens of thermal high heat flux cycles [8][9][10]. Recent studies indicate that its propagation results of an accumulation of plastic strain near the loaded surface [7,11] which is aggravated by the tungsten softening process (microstructure change) [5].…”

Section: Assumptionmentioning

confidence: 99%

“…To better understand the damage process in WEST and perform numerical lifetime assessment, it is thus necessary to predict the mechanical stress and strain fields in tungsten monoblock taking into account the realistic mechanical properties and heat loading. For that, this study can rely on an user-defined model recently developed at CEA which is named RXMAT (Recrystallization coupled elastic-viscoplastic MATerial model) [5]. Upcoming simulations assume quasi steady-state loading (called QST in the following, from 45 MW/m 2 to 70 MW/m 2 ), disruption loading (called DIS in the following, 600 MW/m 2 ) and as a particular case, one of the simulations will model a more realistic disruption event occurring on monoblock just after quasi steady-state heating phase.…”

Section: Assumptionmentioning

confidence: 99%

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Leading edge cracking observed in WEST

Durif¹,

Richou²,

Corre³

et al. 2022

Phys. Scr.

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One of the missions of the WEST tokamak is to test in a realistic tokamak environment, the ITER-like divertor plasma facing components made with tungsten. On exposed leading edges of monoblocks, poloidally-distributed cracks having an average spacing of 0.4 mm, running perpendicular to the cooling tube axis, were observed following the experimental campaigns in 2018. Damage may be induced by different processes which can lead to: brittle fracture below the Ductile to Brittle Transition temperature or ductile failure for which softening (recovery / recrystallization) process plays a major role. To improve our understanding about the leading edge damage process, numerical simulations were run here. The following results are specially studied: (i) the thermal gradients; (ii) the softening fraction gradient and (iii) the stress and strain distributions taking into account the mechanical properties of tungsten (elastic-viscoplastic) and the softening phenomenon. This paper describes the results obtained for a range of WEST steady state parallel heat flux (from 45 MW/m² to 70 MW/m²) and disruption (600 MW/m²) heat loading on the leading edge. Estimated results related to the plastic strain accumulation, give an interpretation of the premature cracking of the monoblock leading edge but do not explain the poloidal distribution. According to the numerical results, brittle fracture are expected under disruption as estimated normal stresses are beyond the material yield stress, along 88% of the leading edge.

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Section: Contextmentioning

confidence: 99%

Section: Assumptionmentioning

confidence: 99%

Section: Assumptionmentioning

confidence: 99%

Section: Assumptionmentioning

confidence: 99%

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Leading edge cracking observed in WEST

Durif¹,

Richou²,

Corre³

et al. 2022

Phys. Scr.

Self Cite

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“…The estimation of this effect on the HI retention in the monoblock can be adressed as in [62] by first computing the plastic strain induced by thermal fields, which is then used in the current modelling as a time and space dependent trap density. It is worth noting that the plastic strain estimation is strongly dependent on metallurgical features (dislocations, GB, grain sizes and orientations ...) that are triggered with temperature [63].…”

Section: 32mentioning

confidence: 99%

Modelling of hydrogen isotopes trapping, diffusion and permeation in divertor monoblocks under ITER-like conditions

et al. 2021

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