Which kind of isotopes are more dangerous in nuclear waste, isotopes with short-half lives or long half-lives?
348341
short-half lives because they are more unstable.
281343
Isotopes: Protium, Deuterium, Tritium (naturally occurring)\nOther isotopes (synthesized):\n\n============================================================\nIsotopes\nMain Article: Isotopes of hydrogen \nHydrogen is the only element that has different names for its isotopes. (During the early study of radioactivity, various heavy radioactive isotopes were given names, but such names are no longer used, although one element, radon, has a name that originally applied to only one of its isotopes.) The symbols D and T (instead of 2H and 3H) are sometimes used for deuterium and tritium, although this is not officially sanctioned. (The symbol P is already in use for phosphorus and is not available for protium.)\n\n1H \nThe most common isotope of hydrogen, this stable isotope has a nucleus consisting of a single proton; hence the descriptive, although rarely used, name protium. The spin of a protium atom is 1/2+. [6]\n\n2H \nThe other stable isotope is deuterium, with an extra neutron in the nucleus. Deuterium comprises 0.0184%–0.0082% of all hydrogen (IUPAC); ratios of deuterium to protium are reported relative to the VSMOW standard reference water. The spin of a deuterium atom is 1+.\n\n3H \nThe third naturally occurring hydrogen isotope is the radioactive tritium. The tritium nucleus contains two neutrons in addition to the proton. It decays through beta decay and has a half-life of 12.32 years. Tritium occurs naturally due to cosmic rays interacting with atmospheric gases. Like ordinary hydrogen, tritium reacts with the oxygen in the atmosphere to form T2O. This radioactive "water" molecule constantly enters the Earth's seas and lakes in the form of slightly radioactive rain, but its half-life is short enough to prevent a buildup of hazardous radioactivity. The spin of a tritium atom is 1/2+.\n\n4H \nHydrogen-4 was synthesized by bombarding tritium with fast-moving deuterium nuclei. It decays through neutron emission and has a half-life of 9.93696x10-23 seconds. The spin of a hydrogen-4 atom is 2-.\n\n5H \nIn 2001 scientists detected hydrogen-5 by bombarding a hydrogen target with heavy ions. It decays through neutron emission and has a half-life of 8.01930x10-23 seconds.\n\n6H \nHydrogen-6 decays through triple neutron emission and has a half-life of 3.26500x10-22 seconds.\n\n7H \nIn 2003 hydrogen-7 was created (article) at the RIKEN laboratory in Japan by colliding a high-energy beam of helium-8 atoms with a cryogenic hydrogen target and detecting tritons—the nuclei of tritium atoms—and neutrons from the breakup of hydrogen-7, the same method used to produce and detect hydrogen-5.\n============================================================\n\nWater: H2O (one).
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A sample of the starting element is placed inside a nuclear reactor which produces a lot of neutrons, some of which are absorbed by nuclei in the sample. Different nuclides have different affinities for neutron capture.\n\nPolonium 210 has been in the news lately. It's made via this method from bismuth 209. Bismuth 209 captures a neutron to become bismuth 210 and then quickly emits an electron from the nucleus to become polonium 210.\n\nSome artificial nuclides can be produced by bombarding material with protons or electrons from particle accelerators.\n\nTechnetium 99 is an artificial nuclide that is used in every modern hospital every day for a variety of tests. Te99 is formed from the fission of uranium. It is extracted from spent fuel rods from reactors.
915684
Very roughly:  by comparing the ratio between a radioisotope and its "daughter product", and with the knowledge of the radioisotope's half-life, calculate the amount of time needed for the observed ratio to develop.\n\nIn short, if there is a 50-50 split between the radioisotope and its daughter product, one half-life has passed.
580964
Gamma decay is probably the one you are after.\nTransitions in the energy levels of the nucleons is the process behind it.\nNuclear Magnetic Resonance is also a nuclear process and would make a better answer as the wavelength of radiation is much safer.
869096
It is clearly true.\nThe halflife is the amount of time it takes for half of the atoms in a sample to decay. But it does not mean that the other half will be gone in the second period of time, only half of what is remaining.\nSo in 24,000 years you will have 1/2, in another 24,000 years you will have 1/2 of that, or 1/4. In another 24,000 years you will have half of that or 1/8. In another 24,000 years you will have 1/16, and when 100,000 years is past, you will have between 1/16 and 1/32 of the original amount.\n\nThe link has educational illustrations of the process.\n\n;-D It is better not to make any in the first place!
13485
Nuclear power generation can be safe, but what to do with the waste? Overall I don't think it's a good option.
778367
Elements that heavy would decay extremely fast, like within a tiny fraction of a second. They could never be stable in nature.
36355
first of all, it isn't necessarily 100,000 years.  the radioactive waste is made up of radioactive elements.  the only way to measure the wasting of the radioactivity of a material is by half-life, or the time it takes for half of the waste to lose its radioactivity.  essencially, the waste will always be active, but eventually the amount that it is giving off decreases to an amount that doesn't affect humans.  weather it's 100,000 or 1000000 years depends on the material and how much of it.\n\nthe waste will always be there, but nuclear waste is really just radioactive atoms of elements like plutonium, uranium, etc.  it won't disappear, but it will eventually become harmless.
554348
goldwing doesn't know what he's taking about... Heavy water, which is distiguished by the presence of H-2, or Deuterium, is _not_ radioactive.  It is a stable isotope that does exist naturally (.015% from the table of nuclides), stable nuclei don't emit radioactive particles, radioactive particles are emitted as a means for an unstable nuclei to return to a stable form. The reason it is licensed is because heavy water can harm biogical systems, but not because of radiocativity, but rather because biological systems are quite sensitive to the solvent properties of water (which change when deuterium is substituted for natural hydrogen), given a human would have to drink pure heavy water for over two weeks before he/she became seriously ill, but it's a risk nonetheless.  Another reason that it is licensed for production is because a facility capable of seperating an isotope like H2 from natural hydrogen could potentially seperate another fissile isotope (U-235) from natural Uranium...
34569
When transuranic elements decay, the produce lots of energy. Some of this energy is in the form of photons. These photons are basicly particles of light, exept they are to high frequency to see. As such, they are very dangerous, because they can damage DNA which can lead to cancer.
320615
Nuclear energy is dangerous in the hands of any nation. Contrary to popular belief proliferated by propaganda from the energy industry, there is no safe way to dispose of nuclear waste except launching it into outer space.  Here’s a best answer to one of my questions about the disposal of nuclear waste, “If there was (a safe way to dispose of nuclear waste) we would use nuclear energy. It is not and never was a workable energy source because of the hazards and waste."\n\nAmerica has about 70,000 metric tons of nuclear waste with a half life of 5,000 years.  Our solution was to put this waste in a hole 90 miles outside Las Vegas in an earthquake prone area.\n\nWhat does Iran plan to do with their nuclear waste?
721125
fusion is when two elementary particles collide and combine or fuse to make -- even temporarily -- a new particle. In the graphic below, a form of the hydrogen nucleus -- Tritium -- collides with another form of the hydrogen nucleus -- Deuterium -- to form a new particle. (Deuterium and Tritium are isotopes of hydrogen -- a form of water.) The fused particle is not stable, and quickly decays via the split decay mode into a neutron -- moving very fast, i.e., "hot" -- and a helium neucleus -- also know as an "alpha" particle and energy.\nThe radioactive by-products from fission are undeniably bad. They last for tens of thousands of years and can cause untold problems, the worst of which is through terrosists using the waste products for weapons. The fast neutron from fusion can potentially interact with metals a cause them to become radioactive. This process can be minimized by have neutron shielding between the fusion burn and any metals in the reactor. However, the radioactive metals produced -- and any ash from the fusion burn itself -- is a low-level radioactivity that is not considered dangerous, with half-lives in the tens of years. There is no comparison -- radioactive waste from fission is very dangerous, radioactive waste from fusion is not very dangerous.\nIt is hard for most people to understand where this energy comes from, and how much it is. Most people have heard of Einstein's famous equation:\n\nE = mc2\n\nWhen the fusion reactions listed above occur, a small amount of mass disappears. The small amount of mass is converted into a large amount of energy. How much is large? A typical chemical reaction in which hydrogen and oxygen combine to produce water, releases about 1 eV of energy. The fusion process typically releases 1,000,000 times as much energy. Historically, when people talk about the benefits of nuclear fusion, they refer to how much fuel must be burned to equal to each other.\nNuclear fusion takes water, burns it, releases helium (and a small amount of radiation in the form of neutrons), and converts the missing mass into massive amounts of energy.
221300
Measured by the decay of long-lived radioactive isotopes of elements that occur naturally in rocks and minerals and that decay with half lives of 700 million to more than 100 billion years to stable isotopes of other elements, scientists believe that the age of the earth is approximately 4.4 to 4.6 billion years old.
629035
There may be some, but it's too little to be a health concern.  Even the ambient radiation at Bikini Atoll is not extreme; the danger comes from the local trees (and any local crops), which would take up and concentrate radioisotopes in their tissues.
419931
Rather than radioactive element, let's call it a radioactive isotope.  Why?  Because a radioactive element can decay and still be the same element but have fewer neutrons.  As other posters sort of explained, if an isotope is radioactive then half of it should become something else in the specific half life time.  It could still be the same element, or it might be a lighter element.  Read the link about carbon dating and you might understand how this is useful.
116117
Depends on what you mean by better.  I would say neither actually, because they both produce dangerous waste products.  Nuclear breeder reactors are probably the safest way to produce energy (limiting myself to the two choices you provided) since there are no dangerous byproducts.  Unfortunately, both of these energy forms are from limited resources (as far as we know).  I think we should be tapping into wind and solar (particularly) more than rather finite, polluting energy sources.  Hell, why not build solar fields on the opposite side of the moon and beam the energy via satellites and microwaves?  Oh well, what do I know?