Analysis of thermal-hydraulic transients of the water-cooled eutectic LiPb blanket of NET

For the liquid LiPb blanket concept of NET the response of the first wall and the water cooled blanket to coolant tube blockage, loss of pumping power and coolant tube break events has been evaluated. Thermal-hydraulic calculations were carried out with the code RELAP followed by 2-dimensional transient non-liner heat transfer calculations with the code MARC. The main conclusion is that the concept of two parallel coolant loops provides a good safety measure since a flow coast-down in one coolant loop while the plasma is still burning does not lead to any significant temperature increase of the structures. Also passive shutdown cooling by natural convection flow or thermal radiation is sufficiently adequate to remove the decay heat in first wall and blanket. (orig.)