Parametric study of hydrogenic inventory in the ITER divertor based on machine learning

Area of Science:

• Nuclear Fusion Engineering
• Plasma-Material Interactions
• Computational Physics

Background:

• The International Thermonuclear Experimental Reactor (ITER) utilizes monoblock divertor components to manage high heat and particle fluxes.
• Understanding hydrogen isotope retention within these components is critical for reactor safety and operational efficiency.
• Accurate prediction of hydrogen inventory is essential for ITER's fuel cycle management and tritium accounting.

Purpose of the Study:

• To investigate the influence of key plasma and surface parameters on hydrogen inventory within ITER monoblock divertors.
• To develop a predictive tool for estimating hydrogen retention across various operational scenarios.
• To quantify the total hydrogen inventory in the ITER divertor for a specific detached plasma scenario.

Main Methods:

• A 2D FESTIM code was employed for parametric simulations of ITER monoblock geometry.
• Gaussian regression analysis was used to process simulated data and generate an inventory map.
• SOLPS code data was utilized to define input parameters for a detached ITER divertor scenario.

Main Results:

• Hydrogen inventory is significantly dependent on monoblock surface temperature, decreasing as temperature increases.
• Simulations revealed a power-law relationship between hydrogen inventory and exposure time.
• The derived inventory map allows for flexible estimation of hydrogen retention under diverse plasma conditions.
• For a detached ITER scenario, monoblock hydrogen inventory ranged from [Formula: see text] to [Formula: see text] H after 1000s exposure.
• Lower hydrogen accumulation was observed at strike points due to higher surface temperatures.

Conclusions:

• The study provides a robust method for assessing hydrogen inventory in ITER divertor monoblocks.
• Surface temperature is a dominant factor controlling hydrogen retention, with higher temperatures leading to lower inventories.
• The total estimated hydrogen inventory in the ITER divertor for the analyzed detached scenario is approximately 8 grams after 1000s exposure.