Radioactive waste

So radioactive waste is especially hazardous. And I think one of the things that, that people are really scared about radioactivity is you can’t see the damn stuff. So people are scared because not only can they not see it, but because radioactive decay is a complicated process, it’s often times difficult to understand as well. So it’s this sort of boogeyman of, I can’t see it and I can’t understand it. And so it’s really really scary. And you should be scared of radioactivity, but fortunately it’s probably not a waste, hopefully that you will not come across very often in your life.

Now, radioactive isotopes or nuclides are often used Now, radioactive isotopes or nuclides are often used in our daily lives, to do lots of different things. And medical isotopes are probably the most salient example of where radioactive isotopes are used in our daily lives. And these could be things from iodine 131 for thyroid studies or thyroid treatment. Cesium 137 for radiotherapy. Or if you live in an area with a nuclear power plant that generates electricity for you, uranium 238 is often the radioactive byproduct of nuclear fuel. Now, half-lives are essentially how long it takes for that Now, half-lives are essentially how long it takes for that radioactive isotope to decay.

And if you have like a kilogram of radioactive isotope, the half-life is how long it takes for 500 grams of that one kilogram to decay. And it’s an average lifetime cause it’s a stochastic process. But on average iodine 131 has a half-life of eight days, meaning usually half of it is gone in eight days and it’s decayed to some other product, either radioactive or stable. Cesium 137 has a half-life of 30 years, meaning it takes 30 years for half of that cesium to decay to its daughter products. And then you go to uranium 238 it’s got a half-life of 4 billion years. And so different radioactive isotopes have different half-lifes. Some are long, some are short.

And so we have to consider that when we’re thinking about radioactive waste, is how long, what isotope are we dealing with? And how long is that isotope’s- how persistent in the environment is that isotope? most radioactive isotopes, you know, half-life from 1000 to 10,000 to billions of years. And that’s why they tend to, we start to think about long-term storage for them. We break radioactive waste into two types, low-level and high-level waste. High-level waste tends to be very dangerous. It’s usually the spent fuel rods and other radioactive waste from nuclear power plants. Low-level waste tends to be things like medical waste.

And we tend not to walk around with plutonium rods in our pockets when we go to the hospital, but there are, radiation sources in hospitals quite a bit. When you go to the dentist and they take an x-ray, there’s a radioactive source in that x-ray machine. Radioactive waste used to be disposed of by ocean dumping. And now it’s more frequently, it’s done by temporary storage at power plants. However, that temporary storage has often been for 30, 40, 50 years. And so we call it temporary storage, but that’s just because we don’t have a better place to dispose of it.

And so there’s a lot of issues with storing radioactive waste today, especially from nuclear power plants and from nuclear weapons production. The move always is to try and centralize storage, and it’s got a lot of different benefits. Typically you want to put it in a really stable geological area with low rainfall, very deep water tables, low seismicity and volcanism. So basically you’re talking about the center of continents, like in the middle of Canada or in the middle of Australia or in the middle of Russia, nowhere near the edges of continents. It has to be protected from sabotage as well.

So these, the problem with these though, is that most places on earth are now inhabited and nobody wants a radioactive waste site in their backyard.