A heavily shielded container used for the dry storage or shipment (or both) of radioactive materials such as spent nuclear fuel or other high-level radioactive waste. Casks are often made from lead, concrete, or steel. Casks must meet regulatory requirements and are not intended for long-term disposal in a repository. For additional detail, see Dry Cask Storage and Dry Spent Fuel Storage Designs: NRC Approved for General Use.

The gradual decrease in reactor fuel rod temperature caused by the removal of heat from the reactor coolant system after the reactor has been shutdown.

A general designation applied to radiation detection instruments or survey meters that detect and measure radiation. The signal that announces an ionization event is called a count. For related information, see Detecting Radiation.

The total dose that an occupationally exposed worker receives as a result of repeated exposures to ionizing radiation to to the same portion of the body, or to the whole body, over time. For additional detail, see Information for Radiation Workers.

An ion. An elementary particle (part of an element) carrying a positive or negative electric charge.

The area in a nuclear power plant from which most of the plant's power production and emergency safety equipment can be operated by remote control.

A gas-tight shell or other enclosure around a nuclear reactor to confine fission products that otherwise might be released to the atmosphere in the event of an accident. Such enclosures are usually dome-shaped and made of steel-reinforced concrete.