Tritium Pathways and Handling Problems in a Laser Fusion Reactor

Abstract

The 1000-MW(electric) laser fusion reactor design of the University of Wisconsin, SOLASE, is fueled by inserting cryogenic deuterium--tritium pellets containing a microkilogram of fuel into a spherical cavity having a 6-m radius at a rate of 20 Hz. The cavity is surrounded by a honeycomb graphite structure divided into 16 longitudinal segments through which lithium oxide particles (100 to 200 ..mu..m in diameter and with a pore length of 1 ..mu..m) flow by gravity. The total oxide inventory is 1 Mkg. The lithium oxide, which contains 0.1 wt % water, serves as both a tritium breeder and a heat transport medium. The oxide enters the blanket at 673K and exits at 873K except for a 2% side stream exiting at 1123K, from which the tritium is recovered. At this temperature, a residence time of 300 s at a flow rate of 163 kg/s is required to condense the daily tritium supply as HTO on a cold surface. The 873K lithium oxide is transported to a steam generator fabricated from Croloy tubes. In addition to the fuel, the container, either borosilicate glass or polyvinylalcohol (PVA), and a polymer ablator, the pellets contain a high-Z material, here xenon. Also, approx.30 ..mu..kg ofmore » neon are frozen on the outside surface to ensure cryogenic conditions during flight. Some pellet constituents will react with the wall, resulting in erosion. Unburned hydrogen species will react with graphite to form acetylene at a rate estimated to be 63 pm/s (2 mm/yr) for glass and PVA shells at pumping speeds of 6.4 and 8.4 Pa m/sup 3//s (4.8 x 10/sup 4/ and 6.3 x 10/sup 4/ Torr l/s) at 300 K, respectively. The oxygen debris will erode the graphite by carbon monoxide formation at maximum rates of 6.3 and 25.4 pm/s, respectively, for glass and PVA shells.« less