They have a primary and a secondary containment structure, both made from thick reinforced concrete, to protect against the releaseof radioactive materials.
The human and economic damage from the earthquake and tsunami are terrible, and the apparent releaseof some radioactive materials into the atmosphere compounds the significant sense of unease in global markets.
When a current is applied across the sandwich, the electrons and holes team up at the junction of the two materials and release energy in the form of light.