Radiation shielding design is a field of nuclear engineering that plays an integral part of a nuclear facility layout and overall design. Radiation shielding specialists use effective design of shield walls, access labyrinths, shield doors and service penetrations to protect personnel and the public from the harmful effects of exposure to ionising radiation. Optimisation of a facility’s shielding is used as part of a dose optimisation strategy designed to keep any exposures As Low As Reasonably Practicable (ALARP).