Background: Plutonium decay products and radioactive decay

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Someone commented on the post “Breaking News: Strontium-89, 90 in 79km area and contamination map” asking about Plutonium and Strontium and how they are related.

Its a challenge to communicate basic physical chemistry to such an enormously diverse audience as visits this blog. Let me try just a bit – I may have to do a longer background piece for this soon. Bear with this quick and dirty one for now.

All atoms have nuclei made of protons and neutrons (to name a few subatomic particles) – electrons orbit around the nucleus.

In chemistry, atoms “talk” to each other in many ways – one being the sharing or tossing back and forth of electrons.

With radioactive atoms (elements or nuclides) not only are electrons on the move but also parts of the nucleus in a process called Radioactive Decay.

Radioactive decay is the process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles (ionizing radiation). The emission is spontaneous, in that the atom decays without any interaction with another particle from outside the atom.

As the atoms lose bits of their nuclei they become totally new elements or new isotopes of the original element.

This transformation – decay – is predictable for each radioactive element.

Plutonium

For Plutonium it looks like this:

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This graphic shows you not only the Plutonium decay chain but several others. Focus on the pink path that starts in the upper left corner.

Here is a table that is more detailed:

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Uranium-238

An example is the natural decay chain of 238U, which is as follows:

  • decays, through alpha-emission, with a half-life of 4.5 billion years to thorium-234
  • which decays, through beta-emission, with a half-life of 24 days to protactinium-234
  • which decays, through beta-emission, with a half-life of 1.2 minutes to uranium-234
  • which decays, through alpha-emission, with a half-life of 240 thousand years to thorium-230
  • which decays, through alpha-emission, with a half-life of 77 thousand years to radium-226
  • which decays, through alpha-emission, with a half-life of 1.6 thousand years to radon-222
  • which decays, through alpha-emission, with a half-life of 3.8 days to polonium-218
  • which decays, through alpha-emission, with a half-life of 3.1 minutes to lead-214
  • which decays, through beta-emission, with a half-life of 27 minutes to bismuth-214
  • which decays, through beta-emission, with a half-life of 20 minutes to polonium-214
  • which decays, through alpha-emission, with a half-life of 160 microseconds to lead-210
  • which decays, through beta-emission, with a half-life of 22 years to bismuth-210
  • which decays, through beta-emission, with a half-life of 5 days to polonium-210
  • which decays, through alpha-emission, with a half-life of 140 days to lead-206, which is a stable nuclide.
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Strontium

Strontium-90 decays to the Yttrium isotope 90Y.

90Sr is a product of nuclear fission. It is present in significant amount in spent nuclear fuel and in radioactive waste from nuclear reactors and in nuclear fallout from nuclear tests.

I will revisit this topic in more depth if there are more questions.

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nika

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