Curium-246
Cm-246 · Curium, Z = 96, A = 246
A gigabecquerel of Cm-246 is 87.5 mg of material, which follows from a specific activity of 1.14e+10 Bq/g (0.309 Ci/g). Curium-246 decays by alpha decay with a half-life of 4706 years; forty years leaves 99.41% of today's activity and ten thousand years leaves 22.93%.
Alpha emission is led by 5.386 MeV at 79.0593%, one of 3 recorded lines. None of it reaches through skin, so the limit here is intake, not external dose.
Decay is the only handle: forty years leaves 99.41% of today's activity and ten thousand years leaves 22.93%, with ten half-lives at 47,059 years and a mean life of 6,789 years per atom.
Half-life 4706 years, 1.14e+10 Bq/g, and no line recorded
| Half-life | 4706 years (1.485e+11 s) |
| Decay mode | alpha decay |
| Specific activity | 1.14e+10 Bq/g (0.309 Ci/g) |
3 alpha lines, strongest 5.386 MeV
3 recorded lines from 5.242 to 5.386 MeV, the strongest 5.386 MeV at 79.0593% of 99.97% total alpha emission.
| Energy (MeV) | Emission probability (%) |
|---|---|
| 5.3857 | 79.0593 |
| 5.3426 | 20.8945 |
| 5.2420 | 0.02 |
Activity over millennia
Ten half-lives is 47,059 years. On any timescale a facility can be planned over the activity is constant — 99.41% is left after forty years — and the mean life 1/λ is 6,789 years.
| 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 | 15,633 years |
| Time to fall to 1 % | 31,265 years |
| Time to fall to 0.1 % | 46,898 years |
Limits — intake, not external dose
- Alpha reaches nothing through skin — Cm-246 is an intake problem, not an external one.
- What every sheet leaves out, internal dose included.
Decay and mass calculators for Cm-246
Other Curium nuclides: Cm-242, Cm-243, Cm-244, Cm-245
Computed from the IAEA Nuclear Data Section — Livechart API (ENSDF) and the NIST X-Ray Mass Attenuation Coefficients. Derivations and citations.