Pebble Bed reactors.

[livingwill]

Pebble bed reactors are nuclear power plants that can't meltdown.  They produce less power 250 MW but you can link them in up to 10 modules to produce 2.5 GW.  The fuel is made into little pebbles in which the uranium or plutonium is chemically bound in such a way as to make reprocessing it difficult. How to dispose nuclear wastes is a political problem not a technical one. The short version is you basically wrap it in glass, stick it in a barrel and put the barrel way below the water line. The site the government chose is a very good site as it is underneath a mountain.

[nuqlar]

As a nuclear engineer, I think pebble bed reactors are a technology that is very much worth pursuing.  However, there are some huge technical challenges to overcome before these things can become mainstream. 

First is the enrichment of the uranium in the "pebbles".  Current designs call for about 9.8% enriched U-235.  This is about twice the enrichment currently used in commercial nuclear power plants.  (It isn't anywhere near "bomb grade" though.)  When the uranium is finished being enriched at an enrichment facility in the U.S. it is in the form of uranium hexafluoride (UF₆).  The typical shipping container for the UF₆ is a Model 30B cylinder as specified in ANSI N14.1.  This cylinder is 30" in diameter and about 82" long and holds a maximum of 5000 pounds of UF₆.  These cylinders are limited by both the ANSI N14.1 standard and various Department of Transportation restrictions to only 4.95% enriched U-235.  The only other approved container to ship the UF6 would be a 5" diameter container that only holds 55 pounds of UF6.  This means there would have to be a lot of containers being shipped to meet the needs of even one power plant.

Secondly, there is no fuel fabrication facility in the U.S. that can make these fuel "pebbles".  Right now, I believe a German facility is producing them for the South African project.

Thirdly, using helium as the heat exchange medium is nice because it doesn't chemically react with anything and won't transmute to another isotope as a result of the neutron flux in the reactor.  But helium is very difficult to work with because it likes to leak out of pumps, valves, flanges, and any other kind of seal.

These hurdles are not only technical in nature, but political as well.  Because of this, I don't see pebble bed reactors becoming a viable technology in this country for commercial power generation anytime in the next 20 years.

[LarryOldtimer]

Just way the word "nuclear" and the American public will panic.  When I obtained a nuclear compaction testing device for the city I worked for, you would have thought it was an atomic bomb from the reactions of others in City Hall when I wanted to store it when not in use in the construction inspectors' office.  I had to have a "safe" welded together of 1/4" steel to house it in, and that "safe" had to be at the maintenance yard to allay the fears of the folks in City Hall.

The nuclear radiation was no more than about that produced from a pre-WWII glow in the dark wristwatch.