1. Japan continued
Nuclear fears

2. What is a Nuclear Meltdown
A nuclear meltdown describes a malfunction of a nuclear reactor. A nuclear meltdown occurs when the middle portion of the nuclear reactor (its "core") is not properly cooled. This can occur when the cooling system fails or is otherwise defective. If this happens, uranium or plutonium or similar materials inside the nuclear reactor become hot and may start melting or dissolving. It is this melting that is a nuclear meltdown.
3. The Reactor in Fukushima
4. Should WE be concerned