Basic reactor theory lesson 1&2 PHYSICS/SCIENCE LATEST EDITION 2024/25 GUARANTEED GRADE A+
Binding energy
The energy equivalent of the mass defect; the amount of energy released when a nucleus is formed from its component parts, also the amount of energy that must be supplied to a nucleus to sepa...
Basic reactor theory lesson 1&2
PHYSICS/SCIENCE LATEST EDITION
2024/25 GUARANTEED GRADE A+
Binding energy
The energy equivalent of the mass defect; the amount of energy
released when a nucleus is formed from its component parts, also the
amount of energy that must be supplied to a nucleus to separate it
into its components
Bohr model
A model of the atom proposed by Nobel Laureate Niels Bohr in 1913
that describes the atom as composed of a dense, positively-charged
nucleus with electrons orbiting around it in fixed orbits of discrete
radii with associated discrete energy states for the atom
Boiling water reactor (BWR)
A nuclear reactor in which water is allowed to boil directly inside
the reactor, thus creating steam; the steam is dried and used to
drive turbines
Breeding reaction
A nuclear reaction whereby a fertile isotope undergoes a series of
radiative captures (n, g) and b- decays to convert to a fissile
isotope
Burnable poison
Sacrificial neutron absorbers placed within the core at the beginning
of the irradiation cycle; these absorbers are necessary to compensate
for the excess fuel required such that the reactor can remain
critical until the end of the irradiation cycle
Condenser
A component of a power plant that condenses the steam leaving the
turbines, changing the steam to liquid water
Control rods
A rod made up of a substance that controls the neutron population
inside a reactor; control rods are used to control the reactor power
and also to provide a mechanism for rapid shutdown of the reactor, if
necessary
Coolant
The medium used to remove heat from the reactor core; the coolant
keeps the reactor from overheating
Coulombic repulsion
Electrostatic force that makes particles with like charge repel each
other along a straight line between their centers; the repulsive
,force decreases with the square of the distance between the two
charges
Critical
State of a reactor when the number of neutrons in each generation
(also, reactor power) remains constant over time
Cross section
A measure of the probability that an interaction of a given kind will
take place between a nucleus and an incident neutron
Daughter
A nucleus formed as the result of radioactive decay
Delayed neutron
Neutron released by a fission product several seconds after the
fission event; delayed neutrons play a very important role in the
ability to control the rate of fission and hence, the power
generation within nuclear reactors
Electron
A negatively-charged particle with little mass orbiting the nucleus
Electron shells
Areas corresponding to energy levels of electrons
Electron volt
The amount of energy gained by an electron when accelerated through a
potential difference of one volt
Electrostatic attraction
Electrostatic force causing opposite charges to attract
Element
The type of atom determined by the number of protons
Fast fission
Fission caused by fast neutrons
Fertile isotope
A non-fissile isotope such as 238U that becomes fissile when it
absorbs one or more neutrons through radiative capture and undergoes
radioactive decay
Fissile isotope
An isotope such as 235U whose binding energy of the last neutron
added is sufficient to provide the critical energy for fission; such
isotopes can undergo fission even with neutrons of negligibly small
kinetic energy such as thermal neutrons
Fission
A neutron interaction in which a nucleus absorbs a neutron, splits
into two new nuclei and releases a large amount of energy; the
resulting fission fragments emit neutrons and gamma rays and then
undergo radioactive decay
Fission fragments
Nuclei formed as the result of fission
, Fission products
The resulting fission fragments after colliding with neighboring fuel
atoms; they slow down and eventually stop moving
Fuel assembly
An array of fuel rods generally arranged in a square lattice and held
in place by metal straps called grid spacers
Fuel rod
A stack of fuel pellets contained within a metal cladding
Ground state
The lowest energy state of a nucleus or an electron
Heat exchanger
A device used to transfer heat from one medium to another; in nuclear
plants, steam generators and condensers are examples of heat
exchangers, the former transferring heat from the primary coolant to
the secondary coolant of a PWR and the latter transferring the heat
from steam to water from a cooling tower or pond
Isotopes
Atoms with the same number of protons (same element) but different
numbers of neutrons
Light water reactor (LWR)
A nuclear reactor that uses H2O, or "light water," as the moderator
and coolant
Mass defect
The difference between the mass of a nucleus and the sum of the
masses of its individual components
Mass-energy equivalence
E=mc2 - the equivalence relationship for mass (m) and energy (E)
derived by Albert Einstein from his Special Theory of Relativity
(parameter c is the speed of light in a vacuum); the equation says
that mass and energy are interchangeable
Moderator
The medium used to slow down fast neutrons
Neutron
A sub-atomic particle with no charge and about the same mass as that
of a proton
Neutron flux
A measure of the intensity of neutron radiation in neutrons/cm2-sec.
It is the number of neutrons passing through 1 square centimeter of a
given target in 1 second
Nuclear force
The attractive, short range force among nucleons
Nucleon
A particle inside a nucleus (a proton or a neutron)
Nucleus
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