22.5. Nuclear Reactors http://www.ck12.org
(a) hydrogen
(b) coal
(c) all isotopes of uranium
(d) only U-235- nuclear reactor:Any of several devices in which a chain reaction is initiated and controlled, with the resulting
heat typically used for power generation and the neutrons and fission products used for military, experimental,
and medical purposes. - moderator:A substance, such as water or graphite, which is used in a nuclear reactor to decrease the speed
of fast neutrons and increase the likelihood of fission. - control rods:One of a number of rods or tubes containing a neutron absorber, such as boron, that can be
inserted into or retracted from the core of a nuclear reactor in order to control its rate of reaction. - fissionable material:Fissionable or fissile material is a substance capable of undergoing nuclear fission as a
result of the impact of slow neutrons. - LWR:the light water reactor (LWR) is a type of nuclear reactor that uses normal water, as opposed to heavy
water, as its coolant and neutron moderator and a solid compound of fissile element as its fuel. Light water
reactors are the most common type of nuclear reactor. - PWR:Pressurized water reactors (PWRs) constitute the large majority of all Western nuclear power plants. A
PWR is one of three types of LWRs. In a PWR, the primary coolant (water) is pumped under high pressure to
the reactor core where it is heated by the energy generated by the fission of atoms. The heated water then flows
to a steam generator where it transfers its thermal energy to a secondary system where steam is generated and
flows to turbines which, in turn, spin an electric generator.
Atoms of the same element always have the same number of protons in their nuclei, but may have differing
numbers of electrons or neutrons. Radioactivity is the result of nuclear decay and the emission of sub-atomic
particles. Quarks are the smallest particles known to date, and are the building blocks of the primary sub-atomic
particles. Nuclear reactors release vast quantities of energy by harnessing the interactions of atomic nuclei.