Decay Simulator: Uranium-221
General data
| Element name | Uranium |
|---|---|
| Chemical symbol | U |
| Atomic number Z | 92 |
| Isotope name (symbol) | Uranium-221 (U-221) |
| Neutron number N | 129 |
| Mass number A=Z+N | 221 |
Interactive radioactive decay simulation of Uranium-221: atom-by-atom decay, full decay chain, charts of nuclei count and activity.
| Half-life | 0.66 μs |
|---|
Radioactive decay series
- Uranium-221 0.66 μs
- Thorium-217 254 μs
- Radium-213 2.73 min
- Radon-209 28.7 min · 86.0%
- Polonium-205 1.79 h · 14.6%
- Francium-213 34.17 s · 14.0%
- Astatine-209 5.42 h · 85.3%
- Bismuth-205 14.91 d · 18.1%
- Radon-213 19.38 ms · 0.077%
- Polonium-209 124 a · 81.9%
- Lead-205 1.70×10⁷ a · 99.6%
- Bismuth-209 2.01×10¹⁹ a · 0.37%
- Thallium-205 stable
Rare branches (below 0.01%)
Rare branches are transformations that occur in fewer than 0.01% of decays, e.g. double beta decay or cluster emission. The nuclides they produce are practically absent from a sample, so they are hidden by default to keep the main path clear. In this series: branches - 1, nuclides - 3.
- Lead-201 9.33 h · 0.0058%
- Thallium-201 3.0421 d · 0.0058%
- Mercury-201 stable · 0.0058%
How to read the simulation
Grid: each pixel is one atom of the starting isotope. When an atom decays, the pixel takes the colour of the decay product - in decay series mode the product can decay further. The moment each atom decays is random, but the probability follows from the half-life, so after one T½ about half of the atoms remain, after two - about a quarter.
Chart N(t): what percentage of the sample atoms each nuclide makes up at a given moment. The line of the starting isotope falls (by half after each T½), the lines of stable products rise, and those of short-lived ones first rise, then fall.
Chart A(t): activity, i.e. the number of decays per second (becquerel, Bq). It depends on the number of atoms and on how fast they decay: for the same number of atoms, the shorter the T½, the higher the activity.
Simulation time runs faster (or slower) than real time - the time scale slider sets the multiplier. This way you can watch the decay of isotopes that live from fractions of a second to billions of years.
Well-known isotopes
- H-3 - Tritium - glowing watch hands, nuclear fusion fuel.
- C-14 - Radiocarbon dating.
- K-40 - Natural radioactivity - in bananas and in our bodies.
- Co-60 - Radiotherapy and radiation sterilization.
- I-131 - Thyroid treatment; Chernobyl fallout.
- Cs-137 - Long-lasting contamination after Chernobyl and Fukushima.
- Rn-222 - Radon in basements and mines.
- Ra-226 - The longest-lived isotope of radium - the element discovered by Marie and Pierre Curie in 1898.
- U-235 - Nuclear power plant fuel; start of the actinium series.
- U-238 - Age of the Earth; start of the uranium series.
- Pu-238 - Power source for space probes (Voyager, Curiosity rover).
- Am-241 - Ionization smoke detectors.
Data sources
- NNDC Wallet Cards 2023 - Data as of 15 October 2024 - licence: Public domain