Confusing use of prefixes with half-lives

March 11th, 2020
by Joseph Magill

Qu.) RB, MINDEF, Netherlands
Dear Nucleonica Team,
I would like to report a confusing use of prefixes in Nucleonica concerning the halflife-values of radionuclides. In the paper version of the KNC, as well as in the online KNCO, the values are in powers of ten (T½ U-238 = 4.5E9). But in the “Universal Nuclide Chart” and the “Dosimetry and Shielding++” the unit is in years with prefixes, like mega-years (My) and giga-years (Gy). Especially that last one is really confusing, since Gy also stands for Gray. Why the use of these prefixes, which are not only unusual, but also confusing? Note; the very high halflife-values are in powers of ten, as I expect it to be, e.g. Bi-209.

(Ans. Nucleonica Team)
You are correct, the display of the half-lives is indeed not consistent in the Apps, KNCO and UNC. In particular the Gy for gigayears is really confusing. Every time we give a Nucleonica training course this always comes up. Users do think this is Gray! We have now initiated an update procedure where the use of hte units is consistent throughout Nucleonica. First results can already be seen in the UNC and other apps.

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