Noise limits on ITER plasma vertical stabilization system imposed by tungsten divertor monoblock thermal fatigue

•Noise in tokamak reactor plasma vertical position drives oscillations in divertor strike points.•Strike point movements drive thermal fatigue in actively cooled tungsten monoblocks.•Fatigue accumulation assessed with Palmgren-Milner’s rule and Rainflow counting.•RMS noise in speed of plasma vertical position must be less than 0.4 ms−1 in ITER.•Natural tokamak vertical plasma oscillations beneficial for divertor power handling.