Shmacky-McNuts: What is ALARA?
"As Low As Reasonably Achievable" - it's an acronym that stands for the realization, that zero sievert is not always achievable in radiation protection. If you work in nuclear facilities, nuclear medicine or decomissioning of nuclear powerplants, you will be exposed to radiation. But the mandatory rule for employers is, to keep the exposition as low as possible
...with achievable means (it is, for example, not reasonably achievable that everyone walks around in a power suit with five inch thick lead plating). That means as short exposition as possible, use of robotics, wherever possible and 100% monitoring of the exposition so that workers who got a significant exposure can be moved to low exposure work areas before they accumulate their allowed annual dose.