Advantages
Actinides | Half-life | Fission products | ||||||||
---|---|---|---|---|---|---|---|---|---|---|
Cm | Puƒ | Cf | Ac№ | 10–22 y | m is meta |
Kr | Cd₡ | |||
Uƒ | Pu | Cmƒ | 29–90 y | Cs | Sr | Sm₡ | Sn | |||
ƒ for fissile |
Cfƒ | Amƒ | Cfƒ | 140 y – 1.6 ky |
No fission products |
|||||
Am | Ra№ | Bk | ||||||||
Pu | Th | Cm | Am | 5–7 ky | ||||||
4n | Cmƒ | Cm | Puƒ | 8–24 ky | ||||||
Npƒ | Uƒ | Th№ | Pa№ | 32–160 ky | ||||||
Cm | 4n+1 | U№ | 211–348 ky | Tc | ₡ can capture | Sn | Se | |||
U | Np | Pu | Cmƒ | 0.37–23 My | Cs₡ | Zr | Pd | I | ||
Pu | № for NORM |
4n+2 | 4n+3 | 80 My | 6-7% | 4-5% | 1.25% | 0.1-1% | <0.05% | |
Th№ | U№ | Uƒ№ | 0.7–14 Gy | fission product yield |
- Although it is currently (2010) uneconomic, a fast neutron reactor can reduce the total radiotoxicity of nuclear waste, and dramatically reduce the waste's lifetime. They can also use all or almost all of the fuel in the waste. Fast neutrons have an advantage in the transmutation of nuclear waste. With fast neutrons, the ratio between splitting and the capture of neutrons of plutonium or minor actinide is often larger than when the neutrons are slower, at thermal or near-thermal "epithermal" speeds. The transmuted odd-numbered actinides (e.g. from Pu-240 to Pu-241) split more easily. After they split, the actinides become a pair of "fission products." These elements have less total radiotoxicity. Since disposal of the fission products is dominated by the most radiotoxic fission product, Cesium 137, which has a half life of 30.1 years, the result is to reduce nuclear waste lifetimes from tens of millennia (from transuranic isotopes) to a few centuries. The processes are not perfect, but the remaining transuranics are reduced from a significant problem to a tiny percentage of the total waste, because most transuranics can be used as fuel.
- Fast reactors technically solve the "fuel shortage" argument against uranium-fueled reactors without assuming unexplored reserves, or extraction from dilute sources such as ordinary granite or the ocean. They permit nuclear fuels to be bred from almost all the actinides, including known, abundant sources of depleted uranium and thorium, and light water reactor wastes. On average, more neutrons per fission are produced from fissions caused by fast neutrons than from those caused by thermal neutrons. This results in a larger surplus of neutrons beyond those required to sustain the chain reaction. These neutrons can be used to produce extra fuel, or to transmute long half-life waste to less troublesome isotopes, such as was done at the Phénix reactor in Marcoule in France, or some can be used for each purpose. Though conventional thermal reactors also produce excess neutrons, fast reactors can produce enough of them to breed more fuel than they consume. Such designs are known as fast breeder reactors.
- The fast reactor doesn't just transmute the inconvenient even-numbered transuranic elements (notably Pu-240 and U-238). It transmutes them, and then fissions them for power, so that these former wastes would actually become valuable.
Read more about this topic: Fast-neutron Reactor
Famous quotes containing the word advantages:
“For, the advantages which fashion values, are plants which thrive in very confined localities, in a few streets, namely. Out of this precinct, they go for nothing; are of no use in the farm, in the forest, in the market, in war, in the nuptial society, in the literary or scientific circle, at sea, in friendship, in the heaven of thought or virtue.”
—Ralph Waldo Emerson (18031882)
“There is no one thoroughly despicable. We cannot descend much lower than an idiot; and an idiot has some advantages over a wise man.”
—William Hazlitt (17781830)
“The respect for human rights is one of the most significant advantages of a free and democratic nation in the peaceful struggle for influence, and we should use this good weapon as effectively as possible.”
—Jimmy Carter (James Earl Carter, Jr.)