Abstract: In some implementations, there is provided an apparatus. The apparatus may include a first steam engine, an intermediate storage, and a second steam engine. The first steam engine may include a first inlet and a first exhaust, wherein the first inlet receives steam from a source of thermal energy. The intermediate storage may be coupled to the first exhaust, wherein the intermediate storage stores thermal energy provided by steam from the first exhaust. The second steam engine may include a second inlet coupled to the intermediate storage. Moreover, at least one of the first steam engine and the second steam engine may produce work. Furthermore, the first steam engine may be driven by the steam received from the source of thermal energy, and the second steam engine may be driven by steam from at least one of the intermediate storage and the first exhaust. Related apparatus and methods are also described.

Abstract: A liquid fluoride salt cooled, high temperature reactor having a reactor vessel with a pebble-bed reactor core. The reactor core comprises a pebble injection inlet located at a bottom end of the reactor core and a pebble defueling outlet located at a top end of the reactor core, an inner reflector, outer reflector, and an annular pebble-bed region disposed in between the inner reflector and outer reflector. The annular pebble-bed region comprises an annular channel configured for receiving pebble fuel at the pebble injection inlet, the pebble fuel comprising a combination of seed and blanket pebbles having a density lower than the coolant such that the pebbles have positive buoyancy and migrate upward in said annular pebble-bed region toward the defueling outlet. The annular pebble-bed region comprises alternating radial layers of seed pebbles and blanket pebbles.