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78 Cards in this Set
- Front
- Back
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Nuclear Fission
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the splitting of a large nucleus such as U-235 into smaller ones with the release of energy
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Chain reaction
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a reaction that becomes self-sustaining. For example nuclear fission become a chain reaction under certain conditions
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Critical mass
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the amount of fissionable fuel required to sustain a chain reaction
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Primary coolant
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a liquid that come in direct contact with a nuclear reactor to carry away heat
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Moderator
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a material that slows the speed of the neutrons in nuclear reactor making them more effective in causing fission
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Secondary coolant
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the water in steam generator that does not come in contact with the reactor
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Enriched uranium
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uranium that has a higher percent of U-235 than .7% the natural abundance
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Gaseous diffusion
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a process in which a gas is forced through a series of permeable membranes to separate molecule of different masses
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Depleted uranium (DU)
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uranium (U-238) that has been depleted of the small amount of U-235 that it once naturally contained
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Half-life
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for a particular radioisotope the time required for the level of radioactivity to fall to one-half of its value
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High-level radioactive waste (HLW)
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nuclear waste with high levels of radioactivity. HLW requires essentially permanent isolation form the biosphere because of the long half-lives of the radioisotopes involved. It consists of the radioactive materials that result from the reprocessing of spent nuclear fuel
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Low-level radioactive waste (LLW)
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waste such as clothing, shoes, filters, or medical equipment that is contaminated with smaller quantities of radioactive material than HLW contains. This category specifically excludes spent nuclear fuel
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Spent nuclear Fuel (SNF)
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the radioactive material remaining in fuel rods after they have been used to generate power in a nuclear reactor
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Breeder reactor
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a type of nuclear reactor that created new fissionable fuels (e.g., Pu-239) while the current fissionable fuel of the reactor (U-235) undergoes fission
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Radioactivity
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the spontaneous emission of radiation by certain radioisotopes, such as C-14 or I-131
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Alpha particle
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(α) a positively charged (+2) particle that consist of the nucleus of helium atom-two protons and two neutrons
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Beta particle
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(β) a high speed electron emitted from a nucleus
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Gamma ray
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(γ) high energy, short wavelength photons that may be emitted form the nucleus during the process during the process of nuclear decay
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Radioisotope
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a radioactive isotope of an element
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Radioactive decay series
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a characteristic pathway of radioactive decay that begins with a heavier isotope such as U-238 and ends with a stable isotope such as Pb-206
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Background radiation
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the average daily amount of radiation to which we each are exposed. The amount of background radiation depends on location
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Curie (Ci)
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a measure of radioactivity equivalent to the number of decays per second from one gram of radium
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Rad(radiation absorbed dose)
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a unit of radiation that indicated the absorption of 0.01 J of radiant energy per kilogram of tissue
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Rem (roentgen equivalent man)
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a unit of equivalent dose that indicated the damage done by a particular dose of radiation. A rem is the number of rads multiplied by the quality factor Q
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Sievert (Sv)
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a unit of equivalent dose equal to 100 rem
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Greenhouse Gases
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gases that are capable of absorbing and reemitting infrared radiation to the atmosphere
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Greenhouse effect
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the process by which atmospheric gases trap and return a major portion of the heat (infrared radiation) radiated by the earth
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Enhanced greenhouse effect
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often used to refer to an energy return of greater than 81%
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Quantized
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only certain energy levels are permitted; a noncontinuous energy distribution that consist of many individual, or discrete, steps
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Atomic mass (atomic weight)
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the mass of an atom expressed relative to a value of exactly 12 for an atom of C-12
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Avogadro’s number
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the number of atoms in exactly 12g of C-12 (6.02 X 10^23); also the number of particle per mole of substance such as covalently bonded molecule
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Mole
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Avogadro’s number of particles being specified
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Molar mass (molecular weight)
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the mass of one mole, or Avogadro’s number, of whatever particles are being specified
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Anaerobic bacteria
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bacteria that thrive without the use of molecular oxygen
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Global warming potential(GWP)
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a number that represents the relative contribution of a molecule of the indicated substance to global warming
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Work
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the form of energy describing movement against a restraining force; equal to the force multiplied by the distance over which the motion occurs
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Energy
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Capacity to do work
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Heat
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the energy that flows for m hotter to a colder object
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Temperature
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the property that determined the direction of heat flow
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Calorie (kcal) calorie (cal)
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the unity used in nutrition 1 cal = 1 kcal = 4.184 kJ
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First law of thermodynamics
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the principle that energy is neither created nor destroyed in a chemical reaction; also called the law of conservation of energy
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Potential energy
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the form of energy related to the position of atoms and molecular structure and stored in chemical bonds
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Kinetic energy
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the energy of motion
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Thermal energy
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the random motion of molecules
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Second law of thermodynamics
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the principle that states that it is impossible to completely convert heat into work without making some other changes in the universe
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Entropy
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randomness or disorder in position or energy
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Combustion
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the rapid combination of oxygen with a substance (e.g. fuel) to form products
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Exothermic
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describes any chemical or physical change that releases heat
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Endothermic
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describes any chemical or physical change that absorbs heat
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Heat of combustion
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the quantity of heat energy given off when a specified amount of substance burns in oxygen
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Bond energy
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amount of energy that must be absorbed to break a specific chemical bond
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Activation energy
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the energy necessary to initiate a reaction
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Hydrocarbons
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compound of hydrogen and carbon
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Alkanes
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a hydrocarbon with only single bonds between carbons
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Distillation
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a purification or separation process in which a solution is heated to it’s boiling point and the vapors are condensed and collected
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Cracking
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chemical process by which large molecules are broken into smaller ones suitable to be used in gasoline.
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Catalytic cracking
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a process by which catalysts are used to promote molecular breakdown at lower temperatures than those used in thermal cracking
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Thermal cracking
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the heating of starting material to a high temperature
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Isomer
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molecules with the same chemical formula ( same number and kinds of atoms) but different molecular structures and properties
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Oxygenated gasoline
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blends of petroleum-derived hydrocarbon with oxygen-containing compounds such as MTBE, ethanol, or methanol
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Reformulated gasoline (RGFs)
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an oxygenated gasoline that contains a lower percentage of certain more volatile hydrocarbons such as benzene found in conventional gasoline
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Biomass
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material produced by biological processes
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Mixture
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A physical combination of two or more substances that may be present in variable amounts,substances retain their identity,may be separated by ordinary physical means
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Pure substance
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matter consisting of only one identifiable substance,cannot be separated by ordinary physical means – you have to change the identity of the substance to break it down further (chemical means)
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Element
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pure substance that cannot be broken down into simpler ones by any chemical means (carbon, gold, copper, oxygen, nitrogen, silicon)
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Compound
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pure substance made up of two or more elements in a fixed, characteristic chemical combination (water, carbon dioxide, calcium carbonate)
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Pure substances
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are distinguished from one another by their properties
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Physical properties
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can be determined without changing the identity of the substance (color, phase at 25oC, density)
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Chemical properties
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have to be determined by changing the identity of the substance (i. e. by chemical means: e. g. how elements combine to form compounds or whether a substance burns in air or not)
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ATOM
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smallest unit of an element that can exist as a stable, independent entity
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MOLECULES
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two or more elements in fixed chemical combination
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Chemical Formulas
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Symbolic way to represent the elementary composition of a pure substance
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Diatomic Elements
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is a molecule composed of two atoms is the elementary particle,H2, N2, O2, F2, Cl2, Br2, I2
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Combustion
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rapid combination of oxygen with a substance (e. g. fuel) to form products
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Volatile
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readily vaporized (passes into the vapor phase)
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Catalyst
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chemical substance that influences the speed of a chemical reaction without being changed itself
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Risk assessment
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Evaluation of scientific data and making predictions in an organized manner about the probabilities of occurrence
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allotropes
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two or more forms of the same element that differ in their properties due to differences in molecular structure or crystal structure
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