Words about measurements and systems

Ionising radiation

Radiation that can change atoms in matter by removing electrons. Not all light or radiation is ionising.

Dose

A measure of the energy that radiation deposits in matter or in the body. Experts use quantities suited to the task and interpret the results.

Active system

A system that uses components such as pumps and motors to do a job.

Passive system

A system that uses natural forces, such as gravity or natural circulation, within conditions that have been designed for and checked.

A distinction to remember

Moving water and removing heat describe different things. The fluid must be able to take in heat and carry it along a path to a suitable destination. A drawing of a pump or a tank alone does not show that this job is guaranteed to happen.