• isotope
  • This nuclear reaction can be used to construct a neutron source by mixing a radioisotope that emits alpha particles such as radium, polonium, or americium with a low-atomic-weight isotope, usually by blending powders of the two materials. (wikipedia.org)
  • Even in the case of the lightest elements where the ratio of neutron number to atomic number varies the most between isotopes it usually has only a small effect, although it does matter in some circumstances (for hydrogen, the lightest element, the isotope effect is large enough to strongly affect biology). (wikipedia.org)
  • decay
  • The unusually low energy released in the tritium beta decay makes the decay (along with that of rhenium-187) appropriate for absolute neutrino mass measurements in the laboratory (the most recent experiment being KATRIN). (wikipedia.org)
  • For example, beta decay of a neutron transforms it into a proton by the emission of an electron, or conversely a proton is converted into a neutron by the emission of a positron (positron emission), thus changing the nuclide type. (wikipedia.org)
  • Neither the beta particle nor its associated neutrino exist within the nucleus prior to beta decay, but are created in the decay process. (wikipedia.org)
  • Since a proton or neutron has lepton number zero, β+ decay (a positron, or antielectron) must be accompanied with an electron neutrino, while β− decay (an electron) must be accompanied by an electron antineutrino. (wikipedia.org)
  • Pure Pu-238 for radioisotope thermoelectric generators that power some spacecraft is produced by neutron capture on neptunium-237 but plutonium from spent nuclear fuel can contain as much as a few percent of Pu-238, from either 237Np, alpha decay of 242Cm, or (n,2n) reactions. (wikipedia.org)
  • absorption cross s
  • This reaction has a quite small absorption cross section, making heavy water a good neutron moderator, and relatively little tritium is produced. (wikipedia.org)
  • Pu-240 does have a moderate thermal neutron absorption cross section, so that Pu-241 production in a thermal reactor becomes a significant fraction as large as Pu-239 production. (wikipedia.org)
  • uranium
  • Plutonium (94Pu) is an artificial element, except for trace quantities resulting from neutron capture by uranium, and thus a standard atomic weight cannot be given. (wikipedia.org)
  • It contained 45,000 graphite blocks weighing 400 short tons (360 t) used as neutron moderators, and was fueled by 6 short tons (5.4 t) of uranium metal and 50 short tons (45 t) of uranium oxide. (wikipedia.org)
  • They discovered significant neutron multiplication in natural uranium, proving that a chain reaction might be possible. (wikipedia.org)
  • particle
  • Several sharp peaks below A = 30 correspond to nuclei 4 He, 8 Be, 1 C, 16 O, 0 Ne and 4 Mg. The 4 He nucleus (α particle) is particularly stable and the A and Z of the other nuclei are multiples of the α particle. (docplayer.net)
  • emits
  • In the process of achieving stability a part of the nucleus of a radioisotope disintegrates and emits particles and energy. (ratical.org)
  • stability
  • The chapter covers atomic structure, nuclear structure, the classification of nuclei, binding energy and nuclear stability. (wikibooks.org)
  • 1 Section 7: In this section, we present a basic description of atomic nuclei, the stored energy contained within them, their occurrence and stability Basic Nuclear Concepts EARLY DISCOVERIES [see also Section ] Radioactivity - discovered in 1896 by Henri Becquerel. (docplayer.net)
  • reaction
  • In the most important reaction for natural production, a fast neutron (which must have energy greater than 4.0 MeV) interacts with atmospheric nitrogen: Worldwide, the production of tritium from natural sources is 148,000 terabecquerels per year. (wikipedia.org)
  • In order to efficiently convert the heat produced by the Nuclear Reaction into electricity, the water that moderates the neutron and cools the fuel elements is contained at pressures 150 times greater than atmospheric pressure. (nuclearinfo.net)
  • trace
  • Naturally occurring tritium is extremely rare on Earth, where trace amounts are formed by the interaction of the atmosphere with cosmic rays. (wikipedia.org)
  • physics
  • The term Atomic Number is defined in nuclear physics as the number of protons in a nucleus and is given the symbol Z . From your chemistry you will remember that this number also defines the position of an element in the Periodic Table of Elements . (wikibooks.org)
  • heavy water
  • 2,800 short tons) of heavy water a year, and it separates out about 2.5 kg (5.5 lb) of tritium, making it available for other uses. (wikipedia.org)
  • half life
  • While tritium has several different experimentally determined values of its half-life, the National Institute of Standards and Technology lists 4,500 ± 8 days (12.32 ± 0.02 years). (wikipedia.org)
  • small
  • In the early 1900s, Rutherford and co-workers, by performing experiments scattering particles off gold, confirmed the planetary model with a small, massive nucleus at its centre. (docplayer.net)
  • contaminated water
  • In January 2014 it was made public that a total of 875 TBq (2.45 g) of tritium are on the site of Fukushima Daiichi, and the amount of tritium contained in the contaminated water is increasing by approximately 230 TBq (0.64 g) per year. (wikipedia.org)
  • moderator
  • Even so, cleaning tritium from the moderator may be desirable after several years to reduce the risk of its escaping to the environment. (wikipedia.org)
  • natural
  • The global equilibrium inventory of tritium created by natural sources remains approximately constant at 2,590,000 terabecquerels. (wikipedia.org)