GC: n
CT: An idea to dispose of the waste underground in Antarctica sounded promising: heat from the radioactive decay would melt ice sheets below the waste, causing it to sink. But this plan was abandoned due to international treaties aimed at preserving the near pristine state of the continent. Sea dumping – which was in the past used for lower-level, less hazardous nuclear waste – has been banned too.
S: UN – http://horizon-magazine.eu/article/three-permanent-disposal-sites-radioactive-waste-europe-2025_en.html (last access: 9 December 2015).
N: 1. radioactive (adj): 1898, from French radio-actif, coined by Pierre and Marie Curie from radio-, combinated form of Latin radius and actif “active”.
decay (n): Middle of the 5th century, “deterioration, decline in value,” from decay (v.). Meaning “gradual decrease in radioactivity” is from 1897.
2. A spontaneous nuclear transformation in which particles or gamma radiation are emitted or X radiation is emitted following orbital electron capture, or the nucleus undergoes spontaneous fission.
3. Radioactive decay may produce photons, which are light, but the photons are not in the visible portion of the spectrum.
4. There are three forms of radioactive decay.
Which of these an atomic nucleus undergoes depends on the nature of the internal instability. Some isotopes can decay via more than one pathway.
• Alpha Decay – The nucleus ejects an alpha particle, which is essentially a helium nucleus (2 protons and 2 neutrons), decreasing the atomic number of the parent by 2 and the mass number by 4.
• Beta Decay – A stream electrons, called beta particles, are ejected from the parent, and a neutron in the nucleus is converted into a proton. The mass number of the new nucleus is the same, but the atomic number increases by 1.
• Gamma Decay – In gamma decay, the atomic nucleus releases excess energy in the form of high-energy photons (electromagnetic radiation). The atomic number and mass number remain the same, but the resulting nucleus assumes a more stable energy state.
5. radioactive decay: term and definition standardized by ISO in 1997.
radioactive decay: term used at Natural Resources Canada – Earth Sciences Sector.
S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=radioactive+decay (last access: 9 December 2015). 2. TERMIUM PLUS – http://goo.gl/ZINSYE (last access: 17 December 2015). 3. ABOUT – http://chemistry.about.com/od/nucleardecay/a/Do-Radioactive-Elements-Glow-In-The-Dark.htm (last access: 9 December 2015). 4. ABOUT – http://chemistry.about.com/od/nuclearchemistry/fl/Why-Does-Radioactive-Decay-Occur.htm (last access: 9 December 2015). 5. TERMIUM PLUS – http://goo.gl/ZINSYE (last access: 17 December 2015).
OV: radio-active decay
S: TERMIUM PLUS (last access: 17 December 2015)
SYN: radioactive disintegration
S: TERMIUM PLUS – http://goo.gl/ZINSYE (last access: 17 December 2015)
CR: nuclear energy, radioactivity.
