Polonium-210
Po-210 · Polonium, Z = 84, A = 210
At 1.66e+14 Bq/g — 4.49e+3 Ci/g — a gigabecquerel of Po-210 amounts to 6.01 µg, which is why activity rather than mass is how anyone states the quantity. Polonium-210 decays by alpha decay with a half-life of 138.376 days, falling to 86.05% of today's activity in a month and 16.05% in a year.
Alpha emission is led by 5.304 MeV at 100%. None of it reaches through skin, so the limit here is intake, not external dose.
Decay is the only handle: a month leaves 86.05% of today's activity and a year leaves 16.05%, with ten half-lives at 3.79 years and a mean life of 200 days per atom.
Half-life 138.376 days, 1.66e+14 Bq/g, and no line recorded
| Half-life | 138.376 days (1.196e+7 s) |
| Decay mode | alpha decay |
| Specific activity | 1.66e+14 Bq/g (4.49e+3 Ci/g) |
One alpha line at 5.304 MeV
One recorded line, 5.304 MeV at 100% — monoenergetic as far as this dataset goes.
| Energy (MeV) | Emission probability (%) |
|---|---|
| 5.3043 | 100 |
Activity over months and years
Ten half-lives is 3.79 years — a storage problem rather than a disposal one, with 16.05% of today's activity still there after a year. The mean life 1/λ is 200 days.
| Elapsed | Fraction remaining |
|---|---|
| 1 half-life | 50.0 % |
| 2 half-lives | 25.0 % |
| 5 half-lives | 3.13 % |
| 10 half-lives | 0.0977 % |
| Time to fall to 10 % of today's activity | 1.26 years |
| Time to fall to 1 % | 2.52 years |
| Time to fall to 0.1 % | 3.78 years |
Limits — intake, not external dose
- Alpha reaches nothing through skin — Po-210 is an intake problem, not an external one.
- What every sheet leaves out, internal dose included.
Decay and mass calculators for Po-210
Computed from the IAEA Nuclear Data Section — Livechart API (ENSDF) and the NIST X-Ray Mass Attenuation Coefficients. Derivations and citations.