  In the initial stages of ITER operation, ELM mitigation systems need to be
commissioned. This requires controlled flat-top operation in type-I ELMy H-mode
regimes. Hydrogen or helium plasma discharges are used exclusively in these
stages to ensure negligible production of neutrons from fusion reactions. With
the expected higher L-H power threshold of hydrogen and helium plasmas compared
to corresponding D and D/T plasmas, it is uncertain whether available auxiliary
power systems are sufficient to operate in stable type-I ELMy H-mode. This has
been investigated using integrated core and edge/SOL/divertor modelling with
JINTRAC. Assuming that the L-H power threshold is well captured by the Martin08
scaling law, the presented simulations have found that 30 MW of ECRH power is
likely required for the investigated hydrogen plasma scenarios, rather than the
originally planned 20 MW in the 2016 Staged Approach ITER Baseline. However,
past experiments have shown that a small helium fraction (~10 %) can
considerably reduce the hydrogen plasma L-H power threshold. Assuming that
these results extrapolate to ITER operation regimes, the 7.5MA/2.65T hydrogen
plasma scenario is likely to access stable type-I ELMy H-mode operation also at
20 MW of ECRH.
