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

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.

A positively charged ion.

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 CDE (HT,50) is the dose to some specific organ or tissue of reference (T) that will be received from an intake of radioactive material by an individual during the 50-year period following the intake.

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).

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