Will HTR's be a success?  Because these small reactors are completely melt-down proof, they represent a leap forward in public safety concerns, so the vision of a rural town or even a large industrial facility owning their own nuclear power plant is not beyond the range of our imagination.

The key safety feature are the fuel pebbles have their own containment field.  The original HTR fuel design included self-contained fuel "pebbles" which wrap the Uranium core in a Graphite sphere about the size of a tennis ball.  Each pebble contains about "15,000 fuel particles. Pebbles travel around the reactor core about 10 times in their lifetime. During normal operation, the reactor will be loaded with 450,000 fuel pebbles."  The photo to the right is an early HTR reactor experiment that used the pebble technology.  This plant was built in Germany in the 80s, but shut down for political reasons after the Chernobyl accident in 1988.

Since the 1980s, scientists have also been working on other variations of HTR fuel cells.  General Atomics in San Diego, the atomic energy division of General Dynamics, is working on a "primsatic" fuel configuration, where tiny "three-hundreds of an inch fuel kernals are mixed with graphite and formed into cylindrical fuel rods about two inches long.  The fuel rods are then inserted into holes drilled into the hexagonal graphite fuel element blocks..., which also have helium coolant channels, and are then stacked in the reactor core."

"South Africa is developing the Pebble Bed Modular Reactor, the PBMR, and China has an operating a 10-megawatt HTR of the pebble bed design, with plans to construct a commercial 200-megawatt unit starting in 2009.  General Atomics is developing the Gas Turbine Modular Helium Reactor, GT-MHR, which has a prismatic Fuel Rod design, and Japan is operating a 30-megawatt high temperature test reactor, HTTR, of the prismatic design."

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