Did you know that bananas contain radioactive potassium?

Like many I love eating bananas, so is this something we should worry about?

As a nuclear physicist who does research related to radiation safety, we get questions like that that - whether an object or an area is within safe radiation levels. It’s not often that we’re actually asked about fruit because (spoiler alert) much of the world is just naturally radioactive and bananas are safe for us to eat.

Scenarios we look into can instead involve accidents like Fukushiuma or Chernobyl where quickly mapping where the radiation is is essential in minimizing the damage, or when a lost or unknown source need to be found (like if someone has stolen radioactive material or in a threat scenario with a dirty bomb).

To do this, what is traditionally done is to carry a radiation detector and play the game of hot-and-cold. You see no signal over here, and more over here and that’s how you identify a hotspot.

When mapping radiation you typically want to do it as fast as possible and with as little exposure to people as possible.

One way to tackle both of these that we do at the lab is to hand over the detector to a robot. It can be one on wheels, legs, or a flying one like a drone.

So we have our drone system, we send it up, play some hot and cold but it’s not quite as easy to discern what is seen from up there. To come back to the bananas, they’re not the only things around us that are also radioactive, so is the ground, space, even people - you’ve been radiating on each other and have had thousands of radiation particles pass through you since I started talking. This natural background is nothing to worry about but I worry about it a little bit. The background radiation adds up in our measurements so that when we want to find a weaker radioactive source that signal is hard to spot among background. I write algorithms that utilize statistical tricks and machine learning to really squeeze out the faintest of traces left in the data. 

We combine tools from the robotics world and build 3D maps of the environment as we fly through and let the drone use these tiny hints of signals to direct where it wants to go to as quickly and efficiently as possible map areas and find radiation.

And all this gives us systems that help us stay safe, prepared and healthy. And on that note please continue to enjoy bananas and be your healthy, radiant selfs!