Calculator
Source reload planner
Date at which a sealed source activity falls below a threshold you set, from the isotope half-life.
Time to the thresholddays
- Threshold date
- —
- Half-lives elapsed
- —
- Current activity
- —
Method
t = T½ × log₂(A / A_threshold)
- t — days until the threshold is reached
- T½ — isotope half-life in days
- A — current activity in Ci
- A_threshold — activity threshold in Ci
The delay counts from the reference date, not from the loading date. If the current activity is already below the threshold, no delay is computed.
Indicative result — check it against your authorisation and your dosimetry.