Let's hope this latest attempt to pump water into the reactors and the pools containing the spent fuel rods, works.

A large nuclear reactor will contain hundreds, if not thousands of rods filled with uranium fuel.

Each reactor contains 42 tons of lightly enriched uranium dioxide fuel.

For example, nuclear reactors contain dangerous radiation, and nuclear reactions can cause so much heat that no substance might contain them.

These reactors contained rigid safeguards to ensure they would not be used for a military programme.

Also, at low operating pressure the reactor contains less potential energy.

The reactor in operation contains a total of around 76 t of uranium.

Most pebble-bed reactors contain many reinforcing levels of containment to prevent contact between the radioactive materials and the biosphere.

A typical reactor contains several tons of these pellets arranged in rods that fill the reactor core.

The old reactor contains radioactive material including the radioactive isotopes tritium, strontium-90 and cesium-137.