Fuel rods contain tiny pellets of specially prepared uranium encased in a sheath of zirconium alloy. This metal cladding doesn’t corrode and prevents any radioactive bits from escaping.
It all works fine when the temperature of the rods stays under control. But at the Fukushima Daiichi nuclear power plant, the rods were able to heat up well past design specs. And when zirconium gets hot in the presence of steam, it actually splits the water molecules, making hydrogen gas. If the hydrogen builds up and encounters a spark, boom.
Now M.I.T. researchers have come up with a new cladding made out of silicon carbide. This material forms very hard ceramics that also find use in everything from car brakes to bulletproof vests.
It remains to be seen how well the tough ceramic does when bombarded by neutrons at high pressures and temperatures. But initial results at temperatures up to 1,500 degrees Celsius are promising. The research is in the journal Nuclear Technology.
If adopted, the new cladding would drastically reduce the risk of hydrogen explosions at nuclear power plants. And that's the kind of new nuclear that's not controversial.
—David Biello
