Hello osizer,
our standard 230 kV, 100 Mvar shunt reactors (three-phase units, gapped-core desing, ONAN cooling) have about 175 kW total losses @50 Hz.
For 60 Hz units, you have slightly higher core losses per unit of weight, but these are generally compensated by the reduced core weight, leading to comparable total losses.
I would say that, as long as you do not have strict footprint, weight or transportation constraints, a quality factor (rated power / losses) of q = 500 ÷ 600 is a reasonable expectation for 100 Mvar units. Three-phase units could potentially reach values closer to 600, whereas single-phase shunt reactor banks might be closer to 500.
We have a new ABB 115kV 100MVAR and it's ONAF losses are about 220kW, which I believe includes 12 0.55kW/0.5PF 400V fans, if that's at all helpful. It's not assembled yet, but that's what the nameplate states.