The PFC Erosion in DEMO due to Runaway Electrons

We have estimated the energy deposition of runaway electrons into the tungsten/EUROFER blanket structure for reactor DEMO conditions and calculated the consequent level of thermal erosion. Our simulations indicate that the heat generated by runaway electrons may pose a major lifetime limitation for the W armor. We find that the minimum thickness of W necessary to prevent EUROFER from stress destruction at high temperatures, _min, could be already too large for an efficient cooling. Tungsten layers of thickness _min would erode by surface melting and vaporization since the thermal conductivity time is much larger than expected exposure time to runaways.