In late 2006 the new 20MW Open Pool Australian Light Water Reactor (OPAL) went critical for the first time. Since 2007 thousands of scientists and engineers have used the neutron beam instruments to perform a wide range of non-destructive studies of samples covering physics, chemistry, biology, engineering and materials science. Neutrons provide a wealth of information about the state of materials including structure, residual stress, magnetic properties and dynamic properties. As neutrons scatter from nuclei and not electrons, they are highly penetrating, capable of travelling tens of millimetres into most metals. Neutrons behave, to some extent, like tiny bar magnets and can therefore be used to investigate the magnetic properties of materials such as superconductors and computer memories. Recent engineering studies - often undertaken in situ at industrially relevant conditions - include railway sleepers, turbine blades, polymer processing, lithium battery testing, and titanium alloys.