Gigantic fusion-fission inertial confinement (I.C.) reactor systems can produce much power and very large quantities of nuclear materials such as T, He-3, U-233, Pu, etc. Before engineering such I.C. reactor systems, a much smaller, flexible all-fission I.C. test reactor system should be built. In this test reactor explosions of about 100 tons (420 gigajoules) are contained within a 30 meter diameter sturdy chamber and studies could be made of: containing inertial confinement explosions seriatum; using sodium slurries as the working liquid; processing slurry captured explosion debris; fabricating nuclear explosive assemblies; using Pu, Be, Li, and D for the production of T and He-3; breeding plutonium from depleted uranium; breeding uranium-233 from Th; etc.