Question: what is the most dangerous/risky thing you have done?

Thomas Elias Cocolios answered on 14 Mar 2014:

I regularly produce polonium isotopes and study them for a while. When the experiment is over and you need to take it home, you first have to take it apart and inspect all the pieces. The samples on which I implant the polonium is a super thin carbon foil, thickness 90 nm. It is so thin that you see through it and if you breathe on it, it breaks apart.
And that is where the danger resides: if it breaks apart while you are removing and transporting it to safe containment, the polonium isotopes on their carbon flakes start floating and become airborne and you absolutely want to avoid that!
As a consequence, whenever I open my chamber after an experiment, I wait until everybody else has gone away from the lab, I call up the radio-protection services to assist me (they usually come with 2), I wear a mask (in case a foil breaks) and I work ever so slowly to avoid breaking the foils just by moving them in air.
Although I have broken many foils BEFORE experiments, I have never broken any that carried polonium.
Afterwards, the foils are kept between 2 aluminium plates within a lead castle (the name we give to a safe which walls are made of lead) until the polonium isotopes have decayed back to stability. I can usually reuse the foils the year after (if not broken in the mean time) or I send the supports back to a laboratory in Germany (GSI) where they make new foils for me.
Fun fact: I was producing 210Po for the first time the week-end the story about the Russian spy was released. My grand-mother told me about it over the phone (while in the lab I usually don’t follow the news anymore!) and since then has never forgotten that her grand-son works on polonium!