A novel first wall protection scheme for ion beam ICF reactors

A novel first wall protection scheme for ion beam driven inertial confinement fusion reactors is presented. LIBRA-SP utilizes a self-pinched ion beam transport and is intended as a 1000 MWe power reactor. LIBRA-SP uses rigid HT-9 ferritic steel tubes called PERIT (perforated rigid tubes) units. These tubes are equipped with small nozzles on either side which spray vertical fans of liquid metal, overlapping each other such that the first two rows of tubes are completely shadowed from the target emanations. The target generated X-rays accelerate the LiPb spray through the rapid vaporization of the surface facing the target. Simulations of the behavior of the spray with the BUCKY computer code show that the spray remains intact and is still at liquid density when it hits the PERIT units, producing a peak pressure on the PERITs of several GPa and a total impulsive loading of 72 Pa-s. The spray that is vaporized by the X-rays blows into the center of the target chamber intercepting the target debris ions. The first row of tubes in the blanket carry the brunt of the radial impulsive load, which is applied at the reactor repetition rate. A code has been developed for determining the mechanical transient and steady state response of the tubes containing the liquid metal, driven by sequential pulses for specific boundary conditions. Maximum steady state deflections and bending stresses as a function of the rep-rate are calculated and used to optimize the length of the PERIT units for avoiding resonant conditions. The cylindrical portion of the chamber is covered by a blanket of rigid steel tubes at a packing fraction of 50%. Only the front two rows of tubes are equipped with the spray nozzles. These tubes are at a radius of 4 m, and the radius of the reflector, which is the vacuum boundary, is 5.2 m.