Strontium-90 is a radioactive isotope used in power sources for remote facilities such as arctic weather stations.
The table shows how the activity of a sample of strontium-90 varies over time.
Time (years)01530456075Activity (Bq)1200850600420300210 \begin{array}{|c|c|c|c|c|c|c|} \hline \textbf{Time (years)} & 0 & 15 & 30 & 45 & 60 & 75 \\ \hline \textbf{Activity (Bq)} & 1200 & 850 & 600 & 420 & 300 & 210 \\ \hline \end{array} Time (years)Activity (Bq)012001585030600454206030075210Explain step-by-step how a graph of activity (yyy-axis) against time (xxx-axis) is used to find the half-life of strontium-90.
Use the data in the table directly to find the half-life of strontium-90. Show your working.
The strontium-90 is encased inside a solid steel protective container within a thermoelectric generator module.
Strontium-90 transfers thermal energy at a rate of 0.46 W for every gram of strontium. Calculate the rate of thermal energy output from a strontium-90 core with a mass of 18.5 g.
When strontium-90 decays, it emits beta-minus particles. Explain why an operator can safely handle the outer steel container of the generator module without receiving a radiation dose from the beta particles.
Remote arctic weather stations must operate continuously for several decades without maintenance.
Explain why it is essential to use a radioisotope with a long half-life like strontium-90 rather than an isotope with a short half-life of a few weeks.
