The impact of nuclear analysis on ITER design and licensing

Formation and termination of runaway beams in ITER disruptions

“…r compton e (23) Here γ E is the photon energy, ( ) Γ γ γ E the gamma energy flux spectrum and ( ) σ γ E the Compton cross-section for photons of energy γ E . As an estimate for the gamma flux energy spectrum, an average of the calculations performed at four different poloidal locations in ITER using radiation transport calculations [30] will be used, which can be fitted to (see figure 2):…”

“…There is a contribution to the gamma flux which does not depend on the fusion power as it corresponds to a time integrated activation of the walls, and the typical ratio between prompt during plasma burn and larger timescale decay (between pulses) gamma fluxes is of the order of 1000 [30]. Thus, we assume a worst case scenario in which the gamma flux during the disruption is at a similar level to that during burning plasma conditions, which scales with fusion power.…”

“…1 for an H-mode discharge at 15 MA and 500 MW fusion power [30,31]. At lower currents, the gamma flux is scaled with the fusion power.…”

ITER safety and licensing update

“…These loads have been conservatively estimated and included in the load specifications for the VV design. Nuclear analyses have also been performed [5] to confirm that neutron damage to the VV steel is below the level at which its mechanical properties could be affected. Taking account of neutron streaming paths, the peak accumulated lifetime damage of the VV is calculated to be less than 0.5 dpa, which will have no significant impact on the mechanical properties.…”