NUCLEAR NA LABA Flashcards
is the splitting of an atom into two or more smaller ones
Fission
is the fusing of two or more smaller atoms into a larger one
Fusion
is an actinide element and has the highest atomic mass of any naturally occurring element. In its refined state, it is a heavy, silvery-white metal that is malleable, ductile, slightly paramagnetic, and very dense, second only to tungsten
Uranium
the radioactive chemical element with the symbol Pu, is an actinide metal of silvery-gray appearance that tarnishes when exposed to air and forms a dull coating when oxidized
PLUTONIUM
(also called urania) is a type of uranium concentrate powder obtained from leach solutions, in an intermediate step in the processing of uranium ores. It is a step in the processing of uranium after it has been mined but before fuel fabrication or uranium enrichment.
YELLOWCAKE
discovered radioactivity in 1898, and the existence of isotopes was shown around 1900.
Becquerel
Reactions involving atomic nuclei showed that matter could be transformed into energy.
true
who demonstrated The fission of the atom ? and followed by?
fermi
Meitner and Frisch
The fission of uranium into two nearly equal fragments yields a tremendous amount of energy that appears as heat accompanied by the emission of neutrons and gamma rays with the simultaneous disappearance of corresponding amount of mass in accordance with the well-known Einstein equation e=mc^2
true
The extremely pure uranium dioxide used and all the early pure uranium metal were manufactured using an
ether extraction purification of uranium nitrate hexahydrate
Controlled fission generates heat which can be used to produce steam to drive prime movers, thus generating?
electricity.
In August 1982, 274 nuclear units producing 155 GWe (GWe= electrical GW) were operating in the world. Of these, 58% were pressurized water reactors (PWR), 24 percent boiling water reactors (BWR), 13 percent graphite-moderated, 4.2 percent heavy water-moderated, and 0.6 percent were fast breeder reactors (FBR).
true
first spontaneous decaying substances
isolated by Curies
now replaced by Nuclear reactor-produced isotopes
radium and polonium
absorbs a thermal neutron, then fissions into fragments approx. ½ the original atomic weight, gives up neutrons, substantial amount of heat energy
U-235
Neutrons released by fission are
high energy levels (fast)
235-U + neutron ➡️ fission products + energy + 2.43 neutrons
nuclear reaction
Naturally occurring uranium contains only
0.71% 235U
common isotopes of uranium and thorium
U-238 and Th-232
do not split (fission) on absorbing a neutron but do form other elements that undergo rapid, spontaneous decay to yield isotopes that are fissionable, so they are usable for power production
U-238 and Th-232
isotopes that are not fissile but are convertible to fissile materials
fertile materials
has a long half-life (24,000 years)
has a high cross section (ability to absorb) for fast neutrons and a low critical mass for fast fission
Pu-239
is a major U.S. Department of Energy (DOE) installation for the production of defense nuclear materials.
Savannah River Plant
The early years of the nuclear industry,________ were the major source
South African ores of various types, and Canadian pitchblende
is more abundant in the earth’s crust than mercury and is present in about the same amount as tin and molybdenum. It is widely distributed.
uRANIUM
is a suitable nuclear fuel
THORIUM
exists with only one natural isotope,
tHORIUM
Most of it is obtained as a by-product of the processing of monazite
THORIUM
a complex phosphate, for the extraction of rare earth.
MONAZITE
Mined ores carry only a low concentration _______of uranium.
(around 0.2% U3O8)
Process of separating pure uranium from the uranium containing impurities
REFINING
Conversion of crude yellow cake or uranium metal to metal pure enough for reactor use, free of other elements
PURIFICATION
A process by which the relative abundance of the isotopes of a given element are altered, thus producing a form of the element that has been enriched in one particular isotope and depleted in its other isotopic forms.
ISOTOPE ENRICHMENT
Maximum enrichment is 94% 235U, with a waste containing about 0.3% 235U
The Gaseous Diffusion Process
depends on centrifugal force for the separation
Capital expense is greater than for a diffusion plant , but the energy requirement is only 1/20th as great
GAS CENTRIFUGE PROCESS
Three (3) Fissionable isotopes
: 233U, 235U, and 239Pu.
- reactor-synthesized and extend the amount of fissionable material far beyond that which occurs naturally.
233U and 239Pu
occurs in nature.
235U -
is used where deposits are close to the surface
open pit mining
is used for deeper deposits
underground mining
involves a large pit where stripping out and removal of much overburden (overlying rock) is required.
OPEN PIT MINING
have relatively small surface disturbance and the quantity of material that must be removed to access the ore is considerably less
Underground mines
a compound that when heated forms a gas that can be fed into enrichment plants
uranium hexafluoride
separates gaseous uranium hexafluoride into two streams, one being enriched to the required level known as low-enriched uranium (LEU); the other stream is progressively depleted in 235U and is called “tails,” or simply depleted uranium.
ENRICHMENT PROCESS
A third technology that can be used to enrich uranium is called
LASER ENRICHMENT
in a series of diffusion stages CALLED
CASCADE
Laser separation uses laser technology to selectively excite 235U, the fissile isotope, from the much more abundant 238U isotope
Laser separation
