Two or more forms (or atomic configurations) of a given element that have identical atomic numbers (the same number of protons in their nuclei) and the same or very similar chemical properties but different atomic masses (different numbers of neutrons in their nuclei) and dis...
A systematic method for assessing three questions that the NRC uses to define "risk." These questions consider (1) what can go wrong, (2) how likely it is, and (3) what its consequences might be. These questions allow the NRC to understand likely outcomes, sensitivities, area...
The complex of symptoms characterizing the disease known as radiation injury, resulting from excessive exposure (greater than 200 rads or 2 gray) of the whole body (or large part) to ionizing radiation. The earliest of these symptoms are nausea, fatigue, vomiting, and diarrhe...
Classification of low-level waste (LLW) according to its radiological hazard. The classes include Class A, B, and C, with Class A being the least hazardous and accounting for 96 percent of LLW in the United States. As the waste class and hazard increase, the regulations establ...
3109. 9/MFW/83/09/28/0MEMORANDUM FOR: MichiSEP 20 83- 1 -Distribution:WM File: ZTO9.9WMHL r/fNMSS r/fREBrowningMJBellDJFehringerMFWeber & r/fPMOrnsteinHJMillerJOBuntingPSJustusJTGreevesPDRMRKnappiel F. Weber. WMHLMatthew J. Gordon, WMHLJulia Corrado, WMHTJeffrey Pohle, WMHTTim...
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A chemical combination of two or more elements combined in a fixed and definite proportion by weight.
The nucleus of deuterium. It contains one proton and one neutron. See also Heavy water (D2O).
Those fission products that exist in the gaseous state. In nuclear power reactors, this includes primarily the noble gases, such as krypton and xenon.
The region in a radiation/contamination area where the level of radiation/contamination is significantly greater than in neighboring regions in the area.
The external exposure dose equivalent to the lens of the eye at a tissue depth of 0.3 centimeters (300 mg/cm2).
The rise in temperature of the reactor fuel rods resulting from an increase in the rate of fission in the core.
A U.S. State that has signed an agreement with the U.S. Nuclear Regulatory Commission (NRC) authorizing the State to regulate certain uses of radioactive materials within the State.
A reactor that produces more nuclear fuel than it consumes. A fertile material, such as uranium-238, when bombarded by neutrons, is transformed into a fissile material, such as plutonium-239, which can be used as fuel.
The central portion of a nuclear reactor, which contains the fuel assemblies, moderator, neutron poisons, control rods, and support structures. The reactor core is where fission takes place.
Earthquakes, tornadoes, hurricanes, floods, etc., that a nuclear facility must be designed and built to withstand without loss of systems, structures, and components necessary to ensure public health and safety.
The external whole-body exposuredose equivalent at a tissue depth of 1 cm (1000 mg/cm2). For further information, see Measuring Radiation.
The shutdown of a generating unit, transmission line, or other facility for emergency reasons, or a condition in which the equipment is unavailable as a result of an unanticipated breakdown. An outage (whether full, partial, or attributable to a failed start) is considered "f...
An ion. An elementary particle (part of an element) carrying a positive or negative electric charge.
The term used to define a reactor coolant system at atmospheric pressure and at a temperature below 200 degrees Fahrenheit following a reactor cooldown.
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 substance circulated through a nuclear reactor to remove or transfer heat. The most commonly used coolant in the United States is water. Other coolants include heavy water, air, carbon dioxide, helium, liquid sodium, and a sodium-potassium alloy.
The process by which the number of particles or photons entering a body of matter is reduced by absorption and scattered radiation.