Tritium retention in the ITER/DEMO actively cooled tungsten monoblock in the presence of neutron-induced defects

Tritium retention in ITER like divertor monoblock is simulated with FESTIM adding trapping induced by neutron damage in the tungsten armor. The simulated scenario is a 10 MWm −2 heat flux representing an exposure near the strike line during an ITER attached plasma. The tungsten armor is damaged with rate from 5 dpa/fpy to 100 dpa/fpy in the range of expected DEMO damaging rates. It is observed that the temperature field affects the distribution of the neutron-induced traps with a significant annealing of them in the hottest part of the monoblock, which affects the resulting tritium distribution. The tritium retention is 28 times higher in the damaged monoblock compared to undamaged monoblock after a dpa level of 0.64 dpa with a high dpa rate of 100 dpa/fpy, which is an extreme damage rate for ITER or DEMO. The damaged layer slows down the tritium permeation toward the coolant, acting as a temporary permeation barrier until all the damaged-induced traps are filled. This effect is more effective with higher dpa rates as two extreme regimes exists for the growth of the tritium inventory: (i) limited by the tritium migration (low dpa rates) (ii) limited by the neutron-induced trap creation (high dpa rates). • 2D meshing of ITER like monoblock with appropriate refinement to allow convergence. • Simulations of Tritium migration and trap creation with different dpa rate. • Calculation of macroscopic quantities: inventory and outgassing/permeation fluxes. • Analysis of the effect of neutron-induced traps on tritium migration and retention.