If Uranium 238 has the slowest decay rate out of all atoms/nucleotides, why is it considered the most radioactive?

15 January 2023 2 2K Report

Also, how can you measure and calculate a decay rate when you have not experienced the duration of at least one half life?

The Wikipedia article on Radioactive Decay references a Chinese article written in English, no Chinese language version given because they do not believe in the constancy (invariability) of mass.

https://iopscience.iop.org/article/10.1088/1674-1137/abddae#cpc_45_3_030001_f7

So the first Figure, Figure 1 is for the English speaking Chinese people to confirm why they believe so.

Whereas the last Figure, Figure 7 is to show how ridiculous the Western interpretation is, they convert an Asymmetric normal distribution of the uncertainty into a symmetric form, which is what the west uses. And yet the reference article nowhere mentions the decay rates referred to by the wikipedia article.

Further, the image on wikipedia showing the radioactive decay for Uranium, in the following section:

https://en.wikipedia.org/wiki/Radioactive_decay#List_of_decay_modes

Has no mention of the first 3 decay chains nucleotides, nor the next 3 after Ra 226.

Paul Voytas

Well, 238U is not the longest lifetime. 100Mo which decays by double beta decay is much longer. Part of the answer to the other part depends on how you define "most radioactive", but I would not have said 238U is by any reasonable measure. As far as measuring lifetimes, there are 2 answers: 1) you don't have to wait a full 1/2 life to measure the lifetime because if you have a large number of parent nuclei, a finite number of them will decay in any finite time so you can just use the change in activity over any time interval to measure the lifetime (statistically, you need a big enough change to measure well, but that's a different question) 2) If I know how many nuclei I have and I measure the activity, I can get the decay constant (1/tau) from Activity=number*decay constant.

Paul Voytas

That's not what Image 1 is about.

Problems with 14C dating often arise from sample contamination. That has nothing to do with the basic physics of radioactive decay.

Clock faces mostly used Radium paints.

The use of Uranium in reactors has nothing to do with its radioactivity. Its specific activity is very low as it is for any long-lived nuclide. Uranium is used in reactors because of its release of energy when it fissions after absorbing neutrons.

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