The
minor actinides are the
actinideThe actinoid or actinide series encompasses the 15 chemical elements that lie between actinium and lawrencium included on the periodic table, with atomic numbers 89 - 103...
elements in used
nuclear fuelNuclear fuel is any material that can be consumed to derive nuclear energy, by analogy to chemical fuel that is burned to derive energy. By far the most common type of nuclear fuel is heavy fissile elements that can be made to undergo nuclear fission chain reactions in a nuclear fission reactor;...
other than
uraniumUranium is a silvery-white metallic chemical element in the actinide series of the periodic table that has the symbol U and atomic number 92. Besides its 92 protons, a uranium nucleus can have between 141 and 146 neutrons. The most common uranium isotopes are U-238 and U-235 . A uranium atom has...
and
plutoniumPlutonium is a rare transuranic radioactive element. It is an actinide metal of silvery-white appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen and...
, which are termed the
major actinidesMajor actinides is a term used in the nuclear power industry that refers to the plutonium and uranium present in used nuclear fuel, as opposed to the minor actinides neptunium, americium, curium, berkelium, and californium....
. The minor actinides include
neptuniumNeptunium is a chemical element with the symbol Np and atomic number 93. A radioactive metallic element, neptunium is the first transuranic element and belongs to the actinide series. Its most stable isotope, 237Np, is a by-product of nuclear reactors and plutonium production and it...
,
americiumAmericium is a synthetic element that has the symbol Am and atomic number 95. A radioactive metallic element, americium is an actinide that was obtained in 1944 by Glenn T. Seaborg who was bombarding plutonium with neutrons and was the fourth transuranic element to be discovered. It was named for...
,
curiumCurium is a synthetic chemical element with the symbol Cm and atomic number 96. A radioactive metallic transuranic element of the actinide series, curium is produced by bombarding plutonium with alpha particles and was named for Marie Curie and her husband Pierre.- Characteristics :The isotope...
,
berkeliumBerkelium is a synthetic element with the symbol Bk and atomic number 97. A radioactive metallic element in the actinide series, berkelium was first synthesized by bombarding americium with alpha particles and was named after the University of California, Berkeley...
,
californiumCalifornium is a metallic chemical element with the symbol Cf and atomic number 98. A radioactive transuranic element, californium is used in starting nuclear reactors, optimizing coal-fired power plants and cement production facilities , medical treatment of cancer, and oil exploration via down...
,
einsteiniumEinsteinium is a metallic synthetic element. On the periodic table, it is represented by the symbol Es and atomic number 99. It is the seventh transuranic element, and an actinoid. It was named in honor of Albert Einstein.-Properties:...
, and
fermiumFermium is a synthetic element with the symbol Fm and atomic number 100. A highly radioactive metallic transuranic element of the actinide series, fermium is made by bombarding plutonium with neutrons and is named after nuclear physicist Enrico Fermi...
. The most important isotopes in
spent nuclear fuelSpent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor to the point where it is no longer useful in sustaining a nuclear reaction....
are neptunium-237,
americium-241Americium-241 is an isotope of americium.It is the Americium isotope used in some smoke detectors.atomic mass: 241.056823 u
excess mass: 52930 keV
beta decay energy: -767 keVspin: 5/2-
half life: 432 y...
,
americium-243Americium-243 is a radioactive isotope of americium having 95 electrons and protons and 148 neutrons and has a mass of 243.06138 g/mol.It has a half-life of 7370 years, hence it is not found in nature. It is formed in the nuclear fuel cycle by neutron capture on plutonium-242 followed by beta decay...
,
curiumCurium is a synthetic chemical element with the symbol Cm and atomic number 96. A radioactive metallic transuranic element of the actinide series, curium is produced by bombarding plutonium with alpha particles and was named for Marie Curie and her husband Pierre.- Characteristics :The isotope...
-242 through -248, and
californiumCalifornium is a metallic chemical element with the symbol Cf and atomic number 98. A radioactive transuranic element, californium is used in starting nuclear reactors, optimizing coal-fired power plants and cement production facilities , medical treatment of cancer, and oil exploration via down...
-249 through -252.
Plutonium and the minor
actinideThe actinoid or actinide series encompasses the 15 chemical elements that lie between actinium and lawrencium included on the periodic table, with atomic numbers 89 - 103...
s will be responsible for the bulk of the radiotoxicity and heat generation of used nuclear fuel in the medium term (300 to 20,000 years in the
futureThe future is a time period commonly understood to contain all events that have yet to occur. It is the opposite of the past, and is the time after the present. In the Occidental view, which uses a linear conception of time, the future is the portion of the projected time line that is anticipated...
).
The
minor actinides are the
actinideThe actinoid or actinide series encompasses the 15 chemical elements that lie between actinium and lawrencium included on the periodic table, with atomic numbers 89 - 103...
elements in used
nuclear fuelNuclear fuel is any material that can be consumed to derive nuclear energy, by analogy to chemical fuel that is burned to derive energy. By far the most common type of nuclear fuel is heavy fissile elements that can be made to undergo nuclear fission chain reactions in a nuclear fission reactor;...
other than
uraniumUranium is a silvery-white metallic chemical element in the actinide series of the periodic table that has the symbol U and atomic number 92. Besides its 92 protons, a uranium nucleus can have between 141 and 146 neutrons. The most common uranium isotopes are U-238 and U-235 . A uranium atom has...
and
plutoniumPlutonium is a rare transuranic radioactive element. It is an actinide metal of silvery-white appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen and...
, which are termed the
major actinidesMajor actinides is a term used in the nuclear power industry that refers to the plutonium and uranium present in used nuclear fuel, as opposed to the minor actinides neptunium, americium, curium, berkelium, and californium....
. The minor actinides include
neptuniumNeptunium is a chemical element with the symbol Np and atomic number 93. A radioactive metallic element, neptunium is the first transuranic element and belongs to the actinide series. Its most stable isotope, 237Np, is a by-product of nuclear reactors and plutonium production and it...
,
americiumAmericium is a synthetic element that has the symbol Am and atomic number 95. A radioactive metallic element, americium is an actinide that was obtained in 1944 by Glenn T. Seaborg who was bombarding plutonium with neutrons and was the fourth transuranic element to be discovered. It was named for...
,
curiumCurium is a synthetic chemical element with the symbol Cm and atomic number 96. A radioactive metallic transuranic element of the actinide series, curium is produced by bombarding plutonium with alpha particles and was named for Marie Curie and her husband Pierre.- Characteristics :The isotope...
,
berkeliumBerkelium is a synthetic element with the symbol Bk and atomic number 97. A radioactive metallic element in the actinide series, berkelium was first synthesized by bombarding americium with alpha particles and was named after the University of California, Berkeley...
,
californiumCalifornium is a metallic chemical element with the symbol Cf and atomic number 98. A radioactive transuranic element, californium is used in starting nuclear reactors, optimizing coal-fired power plants and cement production facilities , medical treatment of cancer, and oil exploration via down...
,
einsteiniumEinsteinium is a metallic synthetic element. On the periodic table, it is represented by the symbol Es and atomic number 99. It is the seventh transuranic element, and an actinoid. It was named in honor of Albert Einstein.-Properties:...
, and
fermiumFermium is a synthetic element with the symbol Fm and atomic number 100. A highly radioactive metallic transuranic element of the actinide series, fermium is made by bombarding plutonium with neutrons and is named after nuclear physicist Enrico Fermi...
. The most important isotopes in
spent nuclear fuelSpent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor to the point where it is no longer useful in sustaining a nuclear reaction....
are neptunium-237,
americium-241Americium-241 is an isotope of americium.It is the Americium isotope used in some smoke detectors.atomic mass: 241.056823 u
excess mass: 52930 keV
beta decay energy: -767 keVspin: 5/2-
half life: 432 y...
,
americium-243Americium-243 is a radioactive isotope of americium having 95 electrons and protons and 148 neutrons and has a mass of 243.06138 g/mol.It has a half-life of 7370 years, hence it is not found in nature. It is formed in the nuclear fuel cycle by neutron capture on plutonium-242 followed by beta decay...
,
curiumCurium is a synthetic chemical element with the symbol Cm and atomic number 96. A radioactive metallic transuranic element of the actinide series, curium is produced by bombarding plutonium with alpha particles and was named for Marie Curie and her husband Pierre.- Characteristics :The isotope...
-242 through -248, and
californiumCalifornium is a metallic chemical element with the symbol Cf and atomic number 98. A radioactive transuranic element, californium is used in starting nuclear reactors, optimizing coal-fired power plants and cement production facilities , medical treatment of cancer, and oil exploration via down...
-249 through -252.
Plutonium and the minor
actinideThe actinoid or actinide series encompasses the 15 chemical elements that lie between actinium and lawrencium included on the periodic table, with atomic numbers 89 - 103...
s will be responsible for the bulk of the radiotoxicity and heat generation of used nuclear fuel in the medium term (300 to 20,000 years in the
futureThe future is a time period commonly understood to contain all events that have yet to occur. It is the opposite of the past, and is the time after the present. In the Occidental view, which uses a linear conception of time, the future is the portion of the projected time line that is anticipated...
). There are no fission products with halflife in this range.
The plutonium from a power reactor tends to have a greater amount of Pu-241 than the plutonium generated by the lower
burnupIn nuclear power technology, burnup is a measure of the number of fuel atoms that underwent fission. It is normally quoted in megawatt–days per metric ton of uranium metal or its equivalent , or gigawatt–days/MTU...
operations designed to create weapons-grade plutonium. Because the reactor-grade plutonium contains so much Pu-241 the presence of americium-241 makes the plutonium less suitable for making an atom bomb. The ingrowth of
americiumAmericium is a synthetic element that has the symbol Am and atomic number 95. A radioactive metallic element, americium is an actinide that was obtained in 1944 by Glenn T. Seaborg who was bombarding plutonium with neutrons and was the fourth transuranic element to be discovered. It was named for...
in plutonium is one of the methods for identifying the origin of an unknown sample of plutonium and the time since it was last separated chemically from the americium.
Americium is commonly used in industry as both an
alpha particleAlpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus; hence, it can be written as or . They have a net spin of zero, and normally a total energy of about 5 MeV...
and low
photonIn physics, a photon is an elementary particle, the quantum of the electromagnetic field and the basic "unit" of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
energy gamma radiation source. For instance it is used in many smoke detectors. Americium can be formed by neutron capture of Pu-239 and Pu-240 forming Pu-241 which then decays by beta decay to Am-241. In general, as the energy of the neutrons increases, the ratio of the fission cross section to the neutron capture cross section changes in favour of
fissionIn nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts, often producing free neutrons and lighter nuclei, which may eventually produce photons...
. Hence if
MOXMOX might be a name or acronym for:*Malaysian Oxygen Berhad - A Malaysian company that is specializes in providing total gas solutions.*Mixed Oxide Fuel, from nuclear reprocessing*An alien race in the TimeSplitters 2 video game, the Mox...
is used in a
thermal reactorA thermal reactor uses slow or thermal neutrons. Most power reactors are of this type. These type of reactors use a neutron moderator to slow neutrons until they approach the average kinetic energy of the surrounding particles, that is, to reduce the speed of the neutrons to low velocity thermal...
such as a
boiling water reactorThe Boiling Water Reactor is a type of nuclear reactor used for the generation of electrical power. It is the second most common type of electricity-generating nuclear reactor after the pressurized water reactor . The BWR was developed by the Idaho National Laboratory and General Electric in the...
(BWR) or
pressurized water reactorPressurized water reactors comprise a majority of all western nuclear power plants and are one of two types of light water reactor , the other type being boiling water reactors . In a PWR the primary coolant is pumped under high pressure to the reactor core, then the heated water transfers...
(PWR) then more americium can be expected in the used fuel than that from a
fast neutron reactorA fast neutron reactor or simply a fast reactor is a category of nuclear reactor in which the fission chain reaction is sustained by fast neutrons...
.
Some of them have been found in
falloutFallout is the residual radiation hazard from a nuclear explosion, aptly named because it "falls out" of the atmosphere into which it is spread during the explosion. It commonly refers to the radioactive dust created when a nuclear weapon explodes. This radioactive dust, consisting of hot...
from bomb tests. See
Actinides in the environmentActinides in the environment refer to the sources, environmental behaviour and effects of actinides in Earth's environment. Environmental radioactivity is not limited solely to actinides; non-actinides such as radon and radium are of note....
for details of the actinides in the environment.
Transuranics in LWR spent fuel (burnupIn nuclear power technology, burnup is a measure of the number of fuel atoms that underwent fission. It is normally quoted in megawatt–days per metric ton of uranium metal or its equivalent , or gigawatt–days/MTU...
55 GWdth/T) and mean neutronThe neutron is a subatomic particle with no net electric charge and a mass slightly larger than that of a proton.Neutron are usually found in atomic nuclei. The nuclei of most atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of protons in a...
consumption to fissionFission is a splitting of something into two parts.Fission may refer to:*In physics, nuclear fission is a process where a large atomic nucleus is split into two smaller particles....
| Isotope | Fraction | DLWR | Dfast A fast neutron reactor or simply a fast reactor is a category of nuclear reactor in which the fission chain reaction is sustained by fast neutrons...
| Dsuperthermal |
|---|
| Np-237 |
0.0539 |
1.12 |
| Pu-238 |
0.0364 |
0.17 |
| Pu-239 |
0.451 |
| Pu-240 |
0.206 |
0.44 |
| 0.14 |
| Pu-241 |
0.121 |
| Pu-242 |
0.0813 |
1.76 |
| 1.12 |
| Am-241 |
0.0242 |
1.12 |
| Am-242m |
0.000088 |
0.15 |
| Am-243 |
0.0179 |
0.82 |
| 0.21 |
| Cm-243 |
0.00011 |
| Cm-244 |
0.00765 |
| Cm-245 |
0.000638 |
| Weighted sum |
Negative numbers mean net neutron producer