A 50 Hz alternator is rated 500 MVA, 20 kV with \( X_d = 1.0 \) per unit and \( X''_d = 0.2 \) per unit. It supplies a purely resistive load of 400 MW at 20 kV. The load is connected directly across the generator terminals when a symmetrical fault occurs at the load terminals. The initial rms current in the generator is per unit is _______.