Toshiba has developed a new class of micro size 200 kilowatt nuclear reactors designed to power individual apartment buildings or city blocks.

It uses reservoirs of liquid lithium-6, an isotope that is effective at absorbing neutrons. The process is self-sustaining and can last for up to 40 years, producing electricity for only 5 cents per kilowatt hour, about half the cost of grid energy, the company claims.