Nuclear fuel assembly. Worker carrying out a quality control inspection of nuclear fuel pins at a nuclear fuel assembly factory. If the pins are scratched or damaged, they will not be used. The nuclear fuel pins, which are hollow, are made of zirconium (corrosion-resistant steel) and can be up to 3 metres long. They are designed to be filled with small pellets of nuclear fuel, in this case mixed oxide (MOX) fuel, which is a mixture of plutonium and uranium. Hundreds of fuel pins will be bundled together to form a unit containing hundreds of thousands of pellets, which is then loaded into a nuclear reactor to initiate a controlled nuclear fission reaction. This is the Melox factory in Marcoule, France. Photographed in 2004.