A new generation of nuclear power plants are being designed. The most prominent type is the pebble-bed reactor.

Popular Mechanics looks at the future of nuclear power

Standing in his third-floor office, the fresh-faced nuclear engineer holds what could be the future of nuclear power in his hand: a smooth graphite sphere about the size of a tennis ball.

A typical pebble-bed reactor would function somewhat like a giant gumball machine. The design calls for a core filled with about 360,000 of these fuel pebbles–“kernels” of uranium oxide wrapped in two layers of silicon carbide and one layer of pyrolytic carbon, and embedded in a graphite shell. Each day about 3000 pebbles are removed from the bottom as fuel becomes spent. Fresh pebbles are added to the top, eliminating the need to shut down the reactor for refueling. Helium gas flows through the spaces between the spheres, carrying away the heat of the reacting fuel. This hot gas–which is inert, so a leak wouldn’t be radioactive–can then be used to spin a turbine to generate electricity, or serve more exotic uses such as produce hydrogen, refine shale oil or desalinate water.

The pebbles are fireproof and almost impossible to use for weapons production. The spent fuel is easy to transport and store, though there still remains the long-term problem of where to store it. And the design of the nuclear reactor is inherently meltdown-proof. If the fuel gets too hot, it begins absorbing neutrons, shutting down the chain reaction. In 2004, the cooling gas and secondary safety controls were shut off at an experimental pebble-bed reactor in China–and no calamity followed, says MIT professor Andrew Kadak, who witnessed the test.

This is the one of the safest and cheapest power plants we can build. It’s virtually melt-down proof and it is much more difficult to produce nuclear weapons from the left-over material.

Pebble-bed reactors are partly modular as well. If there’s a problem with a part, you swape modules to repair it. Construction and repair times are much faster and cheaper. They can be built to different sizes and specifications as needed.

Nuclear power is the only power source that is as cost-efficient as burning fossile fuels.

Interestingly, Fossile Fuels cause more deaths than nuclear power. Far more. People forget to factor in the lives lost in the coal mining industry and various other factors.