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C
A symbol for carbon.

Ca
A symbol for calcium.

cadmium
A chemical element with atomic number 48. Cadmium was discovered in 1817 by Friedrich Strohmeyer while he was conducting experiments on zinc carbonate. Later that year two other scientists independently found cadmium in samples of zinc oxide. The name cadmium is derived from kadmeia, Greek for calamine.

Symbol: Cd.
Related to transition metals.


calcium
A chemical element with atomic number 20. Calcium was discovered independently in 1808 by Sir Humphry Davy and by Berzelius and Pontin. The name calcium is derived from calyx, Latin for lime (which is primarily calcium carbonate).

Symbol: Ca.
Related to alkaline earth metals.


calibration
The process of determining the numerical relationship between the observed output of a measurement system and the value, based upon reference standards, of the characteristic being measured.

Reference: 10CFR74.4.

calibration factor
A normalization factor that converts between the value of a measured parameter and the actual value of that parameter in a system. The need for calibration factors arises because detectors and sensors do not directly sample a parameter but instead produce a response that scales with the value of the parameter. An example is the measurement of a gamma-ray energy by a radiation detector that produces an electrical pulse whose total charge is proportional to the energy deposited by a gamma ray.

Reference: LA-UR-95-1911.

californium
A chemical element with atomic number 98. Californium was discovered in 1950 by Glenn Seaborg, Albert Ghiorso, Stanley Thompson, and colleagues at the University of California, Berkeley. It was produced when scientists irradiated a microgram of 242Cm with helium ions. The name californium is derived from University of California at Berkeley.

Symbol: Cf.
Related to actinides.


CANDU
Acronym for Canadian Deuterium Uranium Reactor.

capacity factor
A ratio of the average power output of a power plant to its rated capacity.

Synonym: load factor.
Synonym: plant capacity factor.
Synonym: plant factor.


capture cross section
A measure of the probability that an incident particle or photon will be absorbed by a target nuclide.

Symbol: σc.
Synonym: absorption cross section.
Related to barn.
Related to cross section.
Related to fission cross section.
Related to scattering cross section.


carbon
A chemical element with atomic number 6. Carbon has been known since prehistoric times. The name carbon is derived from carbo, Latin for charcoal.

Symbol: C.

carbon-14
A naturally-occurring radioactive isotope of carbon that has a half-life of 5730 years. High-energy neutrons, produced in the upper atmosphere by cosmic ray interaction, react with 14N through the (n,p) reaction to form 14C. This radioactive carbon eventually mixes with carbon in the lower atmosphere, thereby making 14C naturally available. Ancient sources of carbon, such as coal or petroleum deposits, are too old to contain 14C: the radioactive carbon has decayed away.

Symbol: 14C.

cask
A heavily shielded container used to store or ship radioactive material.

Related to cave.
Related to coffin.
Related to pig.


casket
A synonym for coffin.

cassiopeium
(obsolete term)

A synonym for lutetium.

Symbol: Cp.

category 1 design-basis event
Those natural and human-induced events that are reasonably likely to occur regularly, moderately frequently, or one or more times before closure of the geologic repository operations area.

Related to category 2 design-basis event.
Related to design-basis accident.
Related to design-basis event.


category I quantity
A synonym for formula quantity.

category 2 design-basis event
Natural and man-induced events, not classifiable as category 1 design-basis events that are considered unlikely, but sufficiently credible to warrant consideration, taking into account the potential for significant radiological impacts on public health and safety.

Related to category 1 design-basis event.
Related to design-basis accident.
Related to design-basis event.


cathode ray
(obsolete term)

Electrons emitted by the cathode of a vacuum tube and are accelerated toward the positively-charged anode. Cathode rays were discovered by J. Plücker during the years 1858 and 1862 as a luminous green glow near the cathode of the tube. The position of the glow was found to be affected by strong external magnetic fields. Later studies by W. Hittorf (1869), E. Goldstein (1876) and William Crookes (1879-1885) determined the glow was caused by a stream of particles which had a negative charge.


Related to anode ray.
Related to electron.


cation
A positively charged ion.

Synonym: anode ray.
Synonym: positive ion.
Related to anion.
Related to ion.


cave
A heavily-shielded room for storing or handling highly-radioactive materials. Remote manipulators allow personnel to safely work with the radioactivity.

Synonym: hot cell.
Related to cask.
Related to coffin.
Related to pig.
Cd
A symbol cadmium.

C/D
An acronym for cooldown.

CDE
An acronym for committed dose equivalent.

Ce
A symbol cerium.

CEDE
An acronym for committed effective dose equivalent.
Reference: DOE G 151.1-1; DOE G 441.1-3; DOE G 441.1-8; DOE G 441.1-11; DOE-HDBK-1129-99; DOE M 231.1-2.


cent
A unit of reactivity in a reactor defined as one hundredth of a dollar.

Related to dollar.
Related to effective multiplication factor.
Related to inhour.
Related to reactivity.


cerium
A chemical element with atomic number 58. Cerium was discovered in 1803 by Martin Heinrich Klaproth and by Berzelius and Hissinger. The name cerium is derived from the asteroid Ceres.

Symbol: Ce.
Related to cerium earths.
Related to lanthanides.
Related to rare earths.


cerium earths
Elements with atomic numbers 57 through 62. The set of cerium earths includes the following elements: 57 lanthanum (La); 58 cerium (Ce); 59 praseodymium (Pr); 60 neodymium (Nd); 61 promethium (Pm); 62 samarium (Sm).

Related to cerium.
Related to lanthanum.
Related to neodymium.
Related to periodic table.
Related to praseodymium.
Related to promethium.
Related to samarium.


cesium
A chemical element with atomic number 55. Cesium was discovered by spectroscopic analysis in 1860 by Robert Bunsen and Gustav Kirchoff. The name cesium is derived from caesius, Latin for sky blue.

Symbol: Cs.
Synonym: caesium.
Related to alkali metals.


Cf
Symbol for californium.

CF
An acronym for calibration factor.

chain reaction
A reaction whose products are capable of inducing further reactions. Neutron-induced fission is a common example. The fission reaction produces neutrons that can sustain the reaction, thus forming a chain of linked reactions. Gasoline combustion is an example from chemistry. A spark initiates the combustion, resulting in a release of energy that is sufficient to propagate the reaction.

Related to neutron chain reaction.
Related to neutron generation.


charged particle
A synonym for ion.

chart of nuclides
A map showing the known nuclides. The number of protons in a nucleus is shown on the vertical axis and the number of neutrons is shown on the horizontal axis. Nuclide charts are often colored to visualize a particular property and the nuclide boxes often contain a brief summary of nuclear properties.

Synonym: isotope chart.
Synonym: nuclide chart.
Synonym: Segré chart.
Related to periodic table.


chemical reaction
Related to nuclear reaction.

chemical recombination
Of or pertaining to the process of neutralizing an ion pair.

Synonym: recombination.

chlorine
A chemical element with atomic number 17. Chlorine was first noticed in 1774 by Carl Wilhelm Scheele who thought it was a part of oxygen. In 1810, Humphry Davy proved that it was an independent element and named the element chlorine. The name chlorine is derived from chloros, Greek for greenish-yellow.

Symbol: Cl.
Related to halogens.


chromium
A chemical element with atomic number 24. Chromium was discovered in 1797 by Louis-Nicolas Vauquelin. The name chromium is derived from chroma, Greek for colorful.

Symbol: Cr.
Related to transition metals.


chronic dose
A dose delivered over a period of greater than one day.

Related to acute dose.

chronic exposure
One or more exposures that occur over a period longer than one day.

Related to acute exposure. Related to chronic dose.

chronic radiation dose
A single or multiple doses delivered over a period of greater than one day. Chronic radiation doses can be low enough to cause few effects and to permit recovery, and they can be severe enough to cause radiation sickness and death.

Related to acute radiation dose.
Related to radiation dose.
Related to radiation dose rate.
Related to radiation sickness.


Ci
A symbol for curie.

Cl
A symbol chlorine.

cladding
A synonym for fuel cladding.

cleanup system
A continuous water filtration and demineralization system for reactor coolant systems. It serves to reduce contamination levels in the water and to reduce corrosion.

Cm
A symbol curium.

CM
An acronym for core melt.

Co
A symbol cobalt.

cobalt
A chemical element with atomic number 27. Cobalt was discovered by Brandt in 1735. The name cobalt is derived from Kobold, an evil German spirit, and results from the interference of Cobalt in Copper mining. Until 1540, it was believed that the cobalt mineral was unusable. Adding the mineral to glass produces a bright blue color (from which we get the phrase cobalt blue).

Symbol: Co.
Related to transition metals.


coffin
A shipping cask for spent fuel rods. Coffins are heavily shielded and designed to withstand severe impacts that might occur during transportation.

Synonym: casket.
Related to cask.
Related to cave.
Related to pig.


coincidence
Of or pertaining to events that are coincident.

coincident
Two events that occur nearly simultaneously and can be considered related. In radiation detection nearly simultaneous is defined as close to or less than the time resolution of the detection system.

cold
Not radioactive.

Related to hot.

cold neutron
A neutron with an energy greater than or equal to 5x10-5 eV and less than or equal to 0.025 eV.

Related to continuum region neutron.
Related to epithermal neutron.
Related to fast neutron.
Related to low energy region neutron.
Related to resonance region neutron.
Related to slow neutron.
Related to thermal neutron.
Related to ultra cold neutron.
Related to very cold neutron.


collective dose
The sum of individual doses received in a given period of time by a specified population from exposure to a specified source of radiation.

Related to absorbed dose.
Related to committed dose equivalent.
Related to committed effective dose equivalent.
Related to dose.
Related to dose equivalent.
Related to effective dose equivalent.
Related to integral absorbed dose.
Related to total effective dose equivalent.


columbium
A synonym for niobium.

committed dose equivalent
The dose equivalent to organs or tissues of reference (T) that will be received from an intake of radioactive material by an individual during the 50-year period following the intake.

Symbol: HT,50.
Symbol: H50.
Acronym: CDE.
Related to absorbed dose.
Related to collective dose.
Related to committed effective dose equivalent.
Related to dose.
Related to dose equivalent.
Related to effective dose equivalent.
Related to integral absorbed dose.
Related to total effective dose equivalent.
Reference: 10CFR20.1003.


committed dose
A synonym for dose commitment.

committed effective dose equivalent
Acronym: CEDE.
Related to absorbed dose.
Related to collective dose.
Related to committed dose equivalent.
Related to dose.
Related to dose equivalent.
Related to effective dose equivalent.
Related to integral absorbed dose.
Related to total effective dose equivalent.
Reference: NUREG-0544, Rev. 4.


Compton effect
A synonym for Compton scattering.

Compton scattering
Inelastic scattering of a photon off an atomic electron. The gamma ray transfers part of its energy to an atomic electron, the electron is ejected from the atom, and the gamma ray and electron scatter at angles defined by the energy of the initial and scattered gamma rays: (1/E′) - (1/E) = [h/(mec2)][1-cosq], where E′ is the energy of the scattered gamma ray, E is the initial gamma-ray energy, me is the rest mass of the electron, and q is the angle through which the gamma ray is scattered.

Synonym: Compton effect.

condensate
Water formed by cooling steam in a condenser.

confinement
A synonym for containment.

confinement systems
Those systems, including ventilation, that act as barriers between areas containing radioactive substances and the environment.

Reference: 10CFR72.

containment
(1) (general) The process of confining radioactive nuclides within a vessel.

(2) (nuclear reactors) The process of confining radioactive nuclides to a reactor vessel. It also applies to the reactor building which is designed to confine fission products in the event of a major accident.

(3) (waste disposal) Confinement of radioactive waste within a designated boundary.

(4) (fusion research) The process of confining a plasma.

Synonym: confinement.

containment vessel
Acronym: CV.
A synonym for reactor vessel.


contamination
A synonym for radioactive contamination.

continuum region neutron
A neutron with an energy between 0.01 MeV and 25 MeV.

Related to cold neutron.
Related to epithermal neutron.
Related to fast neutron.
Related to low energy region neutron.
Related to resonance region neutron.
Related to slow neutron.
Related to thermal neutron.
Related to ultra cold neutron.
Related to very cold neutron.
control absorber
A synonym for control rod.

controlled area
(1) It is the area outside of a restricted area but within the area whose access is limited by the operator (licensee). Generally, it is the non-restricted area within the site boundary.

(2) A surface location, to be marked by suitable monuments, extending horizontally no more than 10 kilometers in any direction from the outer boundary of the underground facility, and the underlying subsurface, which area has been committed to use as a geologic repository and from which incompatible activities would be restricted following permanent closure.

(3) It is the area immediately surrounding the storage installation for which the licensee exercises authority over its use and within which spent fuel storage operations are performed.

References: 10CFR20, 10CFR60, 10CFR72.

control rod
A component of a reactor that contains strong neutron absorbers and which is used to control reactor reactivity. General control rods have a reactivity worth of a little more than a dollar and are used to control and regulate the reactor power. Regulator rods are used for fine adjustments, shim rods are used for large changes to the reactivity, and safety rods are used to rapidly decrease the reactivity in the event of accidents.

Acronym: CR.
Synonym: absorber rod.
Synonym: control absorber.
Synonym: power rod.
Related to reactivity worth.
Related to reactivity.
Related to regulator rod.
Related to safety rod.
Related to shim rod.


conversion
1. Of or pertaining to internal conversion.

2. The process of converting a fertile material into fissile material.

3. The process of converting U3O8 into UF6.

converter
A synonym for converter reactor.

converter reactor
A reactor that converts fertile material into fissile material. The term converter often is used to classify reactors that produce fissile material that is different than the reactor fuel. An example is a reactor fueled with 235U that converts 238U into 239Pu (neutron capture followed by beta decay). When the reactor produces a fissile material that is used as the fuel, it is known as a breeder reactor.

Synonym: converter.
Related to breeder reactor.


coolant
A liquid or gas circulated through a reactor to remove heat. Coolants can also act as neutron moderators.

cooldown
Cooling of the fuel rods following reactor shutdown by circulation of coolant through the reactor core.

Acronym: C/D.

copper
A chemical element with atomic number 29. Copper is known from antiquity and has been mined for over 5,000 years. The name copper is derived from Kobber, an island in Cyprus.

Symbol: Cu.
Synonym: cuprum.
Related to transition metals.


core
A synonym for reactor core.

corpuscle
(obsolete term)

It is an early name for the electron, proposed by J. J. Thomson in 1897. It can also be defined as a small particle.

A synonym for electron.

cosmic abundance
The elemental abundance applied to extraterrestrial systems.

Related to elemental abundance.
Related to isotopic abundance.


cosmic radiation
Radiation from outer space. Cosmic rays.

cosmic rays
Relativistic (very-high-energy) particles that enter the Earth's atmosphere and secondary radiations produced by the interaction of these particles with the atmosphere. Photons or particles from outer space. High-energy cosmic rays, with energies of 104-1010 GeV, originate from outside our solar system, while lower-energy cosmic rays (<104 GeV) from our sun. Solar cosmic rays are primarily protons and helium.

counter
A synonym for counting system.
A synonym for scaler.


coulomb
The SI unit of electric charge defined as 1.0 A-s.

Symbol: C.
Related to abcoulomb.
Related to ampere hour.
Related to faraday.
Related to statcoulomb.


count
(1) A single event recorded by radiation detection equipment. (2) The total number of events recorded over a period of time.

counting system
A radiation detection system consisting of one or more detectors, electronics for processing the detector signals, output devices for displaying results, and often computer hardware and software for recording and processing data.

Synonym: counter.

Cp
(obsolete term)

A symbol cassiopeium which is an obsolete synonym for lutetium.

Cr
A symbol chromium.

CR
1. An acronym for control rod.
2. An acronym for control room.


critical
The state of a system that supports a sustained fission chain reaction. A system whose effective multiplication factor is 1.0.

Related to criticality.
Related to subcritical.
Related to supercritical.


critical assembly
Sufficient fissionable material arranged in a geometry that supports a chain reaction. The critical assembly can include a moderator.

Acronym: CCA.

criticality
Of or pertaining to a system that supports a sustained fission chain reaction.

criticality factor
A synonym for effective multiplication factor.

critical mass
That minimum mass of fissionable material that supports a sustained fission chain reaction.

Synonym: critical size.
Synonym: critical volume.
critical organ
The organ or part of a body most sensitive to radiation damage by an ingested radioactive nuclide or by an external radiation source.

critical size
A synonym for critical mass.

critical volume
A synonym for critical mass.

cross section
A measure of the probability that a nuclear reaction will occur. It is the apparent or effective area presented by a target nucleus or particle to an oncoming radiation. The barn is the standard unit for the cross section.

Symbol: σ.
Related to barn.
Related to capture cross section.
Related to fission cross section.
Related to scattering cross section.


Cs
A symbol cesium.

CSD
An acronym for cold shutdown.

Cu
A symbol copper.

cumulative dose
The whole body dose or the dose to a region due to repeated exposure to radiation.

cuprum
A synonym for copper.

curie
A unit of radioactivity defined as 3.7x1010 disintegrations per second. Originally it was defined as the radon emitted by 1 g of radium. An older symbol for the curie is c.

Symbol: Ci.
Related to becquerel.
Related to microcurie.
Related to millicurie.
Related to megacurie.
Related to nanocurie.
Related to picocurie.


curium
A chemical element with atomic number 96. Curium was discovered in 1944 by James, Ghiorso, and Seaborg. It was created by the irradiating of 239Pu with helium ions in the 60-inch cyclotron at the University of California, Berkeley. The name curium was given in honor of Pierre and Marie Curie.

Symbol: Cm.
Related to actinides.


CV
An acronym for containment vessel.
 
 
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