THIS IS A DRILL for a GENERAL EMERGENCY - Thursday, February 28, 2018 PLANT VOGTLE has declared a general emergency.

  • Plant Vogtle

    General Emergency - The most serious of the four NRC classifications. Radioactive material could be released outside the plant site. State and local authorities will take action to protect the public. Sirens may be sounded and local radio and television stations will provide information and instructions. If you're in an affected area, you will be notified by your NOAA weather radio and state and local officials about any actions you need to take.
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For information about activities and conditions in the area surrounding Plant Vogtle:

  • Call the Georgia Emergency Management Agency (GEMA) at 1-800-879-4362 or 404-635-7200

For information on current conditions at Plant Vogtle:

  • Call our recorded information line at 1-888-847-1186

Glossary

A

Air Sampling

The collection and analysis of samples of air to measure its radioactivity or to detect the presence of radioactive substances.

Alpha Radiation

Positively charged particles emitted by certain radioactive materials. The most energetic alpha particle will generally fail to penetrate the skin.

Anticipated Transient Without Scram (ATWS)

See "Transient."

Atom

The basic component of all matter. The smallest part of an element that has all the chemical properties of that element. Atoms are made up of protons, neutrons and electrons.

Availability Factor

Ratio of the number of hours that a plant is available for operation in a given period of time (for example, monthly or annually) to the total number of hours in that same period.

 

B

Background Radiation

The radiation in the natural environment, including cosmic rays and radiation from the naturally radioactive elements both outside and inside the bodies of people, animals and plants. It is also called natural radiation.

Beta Radiation

A charged particle emitted from the nucleus of an atom during radioactive decay. A beta particle is a high-energy electron. Beta particles are easily stopped by a thin sheet of metal.

Biological Shield

A mass of absorbing material placed around a reactor or radioactive source to reduce the radiation to a level that is safe for human beings.

Boiling Water Reactor (BWR)

A nuclear reactor in which water is boiled in the reactor vessel; the resulting steam drives a turbine to generate electricity.BoronA chemical element that absorbs neutrons, thus controlling or stopping a nuclear chain reaction.

Bus

Thick conductor for collecting electric currents and distributing them to outgoing feeders.

C

Capacity Factor

The amount of electricity produced by a given unit over a specified length of time (usually a year), expressed as a percentage of what the unit would have produced if it could have operated at full power, 24 hours a day, over that length of time. For example, a plant operating at full power for a full year has a capacity factor of 100 percent. At half power for a full year or full power for a half year, its capacity factor is 50 percent.

Chain Reaction

A self-sustaining series of events that occurs when a neutron splits an atom and releases other neutrons, with at least one of those neutrons causing another fission to occur.

Circulating Water System

A system that provides cooling water to the main condensers.

Cladding

The outer covering, usually stainless steel or Zircaloy (a zirconium alloy), in which the nuclear fuel is sealed. The cladding serves as a barrier by preventing the release of radioactivity into the coolant.

Cold Shutdown

A reactor condition in which the coolant temperature has been reduced below 200°F and the pressure has been reduced to below 200 psi.

Condenser

A device used in power plants to extract waste heat from steam.

Containment

This is the large airtight concrete building around a reactor to confine fission products that otherwise might be released to the atmosphere in the event of an accident.

Contamination, Radioactive

Deposit of radioactive material in any place where it is not desired, particularly where its presence may be harmful.

Control Rod

A rod, plate or tube containing a material that readily absorbs neutrons. By absorbing neutrons, a control rod prevents the neutrons from causing further fission, thus controlling the power of a nuclear reactor.

Control Room

The operations center of a nuclear power plant from which the plant can be monitored and controlled.

Coolant

A fluid, usually water, used to cool a nuclear reactor and transfer heat energy. The water also moderates, or slows down, neutrons so they will be able to cause fission.

Core

The central portion of a nuclear reactor containing the fuel elements.

Criticality

The point at which a nuclear reactor is just sustaining a chain reaction.

Critical Mass

The smallest amount of fuel necessary to sustain a chain reaction.

D

Decay Heat

The heat produced by radioactive atoms in a reactor after the reactor has been shut down.

Decontamination

The removal of radioactive contaminants from surfaces or equipment, as by cleaning and washing with water or chemicals.

Design Basis Accident (DBA)

In general, this refers to conditions that a piece of equipment or system is designed to withstand. The most important DBA is the loss of coolant accident (LOCA).

Dosimeter

A device, such as a film badge, which can be worn and used to measure the radiation exposure a person receives over a period of time.

Drywell (BWR)

The containment vessel enclosing the reactor and re-circulation system and forming part of the primary pressure suppression system.

E

Emergency Core Cooling Systems (ECCS)

A series of backup safety systems designed to dump thousands of gallons of cooling water into the reactor, thus preventing a core meltdown in the event the normal core cooling system fails.

F

Film Badge

A light-tight package of photographic film worn like a badge by workers in nuclear industry or research. It is used to measure possible exposure to ionizing radiation. The absorbed dose can be accurately calculated by the degree of film darkening caused by the irradiation.

Fission

The splitting of a heavy nucleus into two parts (which are nuclei of lighter elements) accompanied by the release of a large amount of energy and generally one or more neutrons.

Fission Products

The atoms formed when uranium is split in a nuclear reactor. Most fission products are radioactive.

Food Chain

The pathways by which any material (such as radioactive material from fallout) passes from the first absorbing organism through plants and animals to man.

Fuel Rod

A cylindrical rod, 10 to 14 feet long, filled with a stack of fuel pellets containing enriched uranium.

G

Gamma Radiation

High-energy, short-wavelength, electromagnetic radiation similar to x-rays. Gamma radiation is released when fission occurs. Gamma rays are very penetrating and are best shielded by dense materials such as lead.

Geiger Counter

An instrument for detecting and measuring beta and gamma radiation. Sometimes called a frisker.

H

Half-Life

The length of time in which any radioactive substance will lose one-half of its radioactivity. The half-life of a substance may vary in length from a fraction of a second to many years.

Heat Exchanger

A device that transfers heat from one material, such as water or gas, to another substance with no direct contact between the two materials. Two examples are steam generators and feedwater heaters.

Hydrogen Recombiner

A device that combines hydrogen with oxygen, producing water. In this manner, a hydrogen recombiner is able to separate hydrogen from other gases.

I

Ingestion Exposure Pathway (50-mile EPZ)

Area within a radius of approximately 50 miles from the nuclear reactor site. The principal exposure from this pathway would be from ingestion of contaminated water or foods such as milk, fresh vegetables or fish.

Ionizing Radiation

Any radiation displacing electrons from atoms or molecules, thereby producing ions. Examples: alpha, beta, and gamma radiation.

Isotope

Different forms of the same chemical element that are distinguished by having different numbers of neutrons in the nucleus. Almost identical chemical properties exist between isotopes of a particular element. A single element may have many isotopes; for example, hydrogen has three isotopes; protium, deuterium and tritium.

K

Kilowatt

One thousand watts, a unit of power. Most electric plants express their generating capacity in kilowatts or megawatts (1,000,000 watts).

Kilowatt-Hour

A unit of energy consumption that equals 1,000 watts used for one hour. For example, ten 100-watt light bulbs burned for one hour use one kilowatt-hour of electricity.

L

LOCA (Loss of Coolant Accident)

A LOCA can result from an opening in the primary cooling system, such as a pipe break or a stuck-open relief valve (as occurred at Three Mile Island). At the first sign of a LOCA, the reactor would shut down automatically. Although the reactor is shut down, the fuel assemblies would continue to generate heat, so cooling water must continue to circulate through the reactor. If there is an interruption in the main flow of cooling water because a LOCA has occurred, then backup cooling water will be needed. This is provided by a series of redundant safety systems and is designed to provide enough cooling water for possible pipe breaks of all sizes, including an instantaneous break of a main cooling line, the largest type of break.

M

Megawatt

A measure of electrical power equal to 1 million watts.

Meltdown

A buildup of heat in the core caused by insufficient cooling, which causes the fuel to melt.

Millirem

A unit of radiation dosage equal to one-thousandth of a rem. An individual member of the public can receive up to 500 millirems per year according to federal standards. This limit doesn't include radiation received for medical treatment, nor does the limit include the 300 millirems people receive annually from background radiation.

N

Natural Circulation

The coolant (usually water) in a reactor is circulated without pumping, that is, by natural convection resulting from the different densities of relative cold and heated portions.

Neutron (Symbol “n”)

An uncharged elementary particle with a mass slightly greater than that of the proton and found in the nucleus of every atom heavier than hydrogen. Neutrons sustain the fission chain reaction in a nuclear reactor.

Noble Gases

Gases that do not combine chemically with other materials. The noble gases are helium, neon, argon, krypton, xenon, and radon.

Nuclear Regulatory Commission (NRC)

The independent civilian agency of the federal government with the authority to regulate, inspect and oversee the nuclear industry to assure the safe operation of United States nuclear power plants.

P

Plume

A cloud (or imaginary cloud, for ease of description) of airborne radioactive particles moving away from a nuclear plant in a direction and at a speed determined by the prevailing wind.

Plume Exposure Pathway (10-mile EPZ)

For planning purposes, the area within a 10 mile radius surrounding a nuclear plant site. The principal exposure sources from this pathway are: (a) whole body exposure to gamma radiation from the plume and from deposited material, and (b) inhalation exposure from the passing radioactive plume.

Pressurized Water Reactor (PWR)

A reactor in which water, heated by nuclear energy, is kept at high pressure to prevent the water from boiling. Steam is then generated in a secondary loop.

Pressurizer

A high-strength tank containing steam and water used to control the pressure of the reactor coolant, or primary loop in a PWR.

Primary Loop

A closed system of piping that provides cooling water to the reactor and transfers heat energy to the secondary loop.

Proton

A subatomic particle with a positive electric charge.

R

Radiation

Energy in the form of rays or particles given off by certain atoms as they go from an unstable to a stable state.

Radiation Area

Any accessible area in which the level of radiation is such that a major portion of an individual's body could receive in any one hour a dose in excess of 5 millirem or in any five consecutive days a dose in excess of 100 millirem.

Radioactivity

The characteristic of the nuclei of some unstable elements (such as uranium) of spontaneously emitting radiation.

Radiological Control Area

An area in which a worker may be exposed to radiation or radioactive material under supervised/controlled conditions.

Reactor Coolant Pump

A piece of equipment designed to move the coolant through the primary loop so the heat generated in the core can be transferred to steam.

Reactor Core

The central portion of a nuclear reactor containing nuclear fuel, water and control mechanisms as well as the supporting structure.

Reactor Trip

An automatic procedure by which control rods are rapidly inserted into the core of a reactor to stop the chain reaction.

Reactor Vessel

A cylindrical, steel vessel that contains the core, control rods, coolant and structures that support the core.

Redundant System

Each of the safety systems in a nuclear plant has at least one backup system that automatically takes over if the first system should fail for any reason. Since there are at least two systems to do the same thing, they are called redundant.

Relief Tank

A tank designed to condense and store excess steam and water discharged through the pressurizer relief valves on top of the pressurizer.

Relief Valve

A valve that automatically opens to release steam and prevent excessive pressure buildup.

REM (Roentgen Equivalent Man)

A unit of radiation exposure that indicates the potential biological effect on human cells.

Restricted Area

Any area to which access is controlled by the licensee for purposes of protection of individuals from exposure to radiation or radioactive materials.

S

Safety Analysis

An assessment of the design and performance of structures, systems and components with respect to risk to the public during accident conditions. The analysis also looks at ability to prevent accidents and mitigate consequences of accidents should they occur.

Scram

To shut the reactor down fast.

Secondary Loop (PWR Only)

A system of piping that carries non-radioactive water. Water in the secondary loop absorbs heat from water in the primary loop through the steam generator tubes, is boiled, and, as steam, is used to spin the turbines.

Shielding

Material, such as lead or concrete, used to protect workers and equipment from exposure to radiation.

Spent (Depleted) Fuel

Nuclear reactor fuel that has been used to the extent that it can no longer effectively sustain a chain reaction.Spent Fuel PoolA pit constructed of reinforced concrete used for the on-site underwater storage of spent fuel assemblies after their removal from the reactor core.

Stack

A chimney used to disperse any gaseous radioactive releases from reactor operation.

Stack Gas

The ventilati