Thorium

As opposed to the huge uranium reactors, nuclear installations based on Thorium can be of all sizes and can also be designed modular. Their power scales from 10 MW to 300 MW. 

For the only technology of Pebble Bed Reactors, there were many scales of reactors built at the beginning of the history of the industrial nuclear power.

The AVR Arbeitsgemeinschaft VersuchsReaktor, built in Jullich (D) had a power of 15 MWe.

The Thorium High Temperature Reactor (THTR) built in Uentrop (D) had a power of 300 MWe.

The new industrial projects range also from 165 MWe (Pebble Bed Modular Reactor started at Koeberg ZA) to 210 MWe (HTR-PM which will be commercialised by the Chinese university of Tsinghua).

Another tentative, the NEREUS project, aimed to realise a modular installation of 8 MWe, consisting of well-proven nuclear, heat exchanger and gas turbine technologies. "It consisted of a well-proven, inherently safe, helium cooled,  closed cycle, graphite moderated, High Temperature Reactor (HTR) as heat source. This was indirectly coupled via a double loupe helium system with heat exchangers, to a recuperative open-cycle Gas Turbine (GT) of the type turbo expander (HTR-GT). The design incorporated the philosophies of the non-utility markets. These markets are : stand-alone heat production, Combined Heat & Power production, stand-alone electricity generation and as prime mover on board ships (the biggest market in numbers and thus the most important one)."