An event or sequence of events that result in the melting of part of the fuel in the reactor core.

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.

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.

A positively charged ion.

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

An expression of the likelihood that, given the way a reactor is designed and operated, an accident could cause the fuel in the reactor to be damaged.

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.

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.

As defined in Title 10, Section 20.1003, of the Code of Federal Regulations (10 CFR 20.1003), the CEDE (HE,50) is the sum of the products of the committed dose equivalents for each of the body organs or tissues that are irradiated multiplied by the weighting factors (WT) applicable to each of those organs or tissues (HE,50 = ΣWTHT.50).