Contamination - The deposition of unwanted radioactive material on the surfaces of structures, areas, objects, or people where it may be external or internal. Decontamination - the reduction or removal of radioactive contamination from a structure, object, or person; decontamination showers use tap water at high pressure with a lot of soap, and shower must last for a minimum of 15 minutes.

A condition in which the containment structure is intact and all systems which operate to ensure its effectiveness as a fission product barrier are functional.

Fuel pellets contain radiation. There are three levels/barriers of containment that prevent radiation from being released: fuel cladding/rods, reactor coolant (water), and the containment building. The first barrier is the fuel rod/cladding, which contains the radioactive fuel pellets. A "loss of fuel cladding/first barrier" occurs if there is damage to the cladding that may result in a release of radiation into the reactor coolant system.

A component which serves to condense steam back into water so that the water can be reused. The main condenser serves to condense the steam exhausted from the main turbine so that it can be pumped back to the steam generators for reheating and conversion back to steam.

A plant condition in which the reactor is shut down (sub-critical) and the reactor coolant temperature is below the boiling point.

A cooling water system that removes excess heat from the main condenser by continuously supplying cooled water from a cooling tower, river or lake to the main condenser and returning the heated water to a cooling tower, river or lake.

The central location from which plant security activities are monitored and controlled. Like the control room, the central alarm station is continuously manned.

A valve which serves to reduce pressure in a steam generator by allowing steam to be relieved to the atmosphere. The released steam is not radioactive.