What comes to mind when you try to picture radioactive waste?
Perhaps a slimy neon green goo oozing out of yellow drums? Many people hold this mental image in their heads. We can thank The Simpsons for that, among others. Fortunately, conditions in Springfield are a far cry from reality! Besides, there is not just one kind of radioactive waste.
Here is an overview of radioactive waste types in Switzerland, including their properties and origins.
All radioactive waste is toxic
Regardless of name or origin, radioactive waste is dangerous because it emits ionising radiation. Colloquially, we say it is radioactive.
For this reason, humans and the environment must be protected. For Switzerland, the solution is disposal in a deep geological repository.
The two main waste categories are high-level waste (HLW) and low- and intermediate-level waste (L/ILW).
A third category is sometimes referred to as alpha-toxic waste (ATW). This category is special, not only because of its small volume, but also because it contains many so-called alpha emitters. While this type of radiation can easily be shielded, its alpha emitters generally have a long half-life. This means that they decay only slowly and thus emit radiation for a very long time.
Yes, they radiate, but no, they don’t glow: fuel rods from nuclear power plants
Nuclear power plants produce high-level waste, mostly in the form of spent fuel assemblies. They look far less spectacular than they do in The Simpsons: they are neither green, nor do they glow. But they are highly toxic: the radioactivity of spent fuel will not return to natural levels for at least around 200,000 years.
We can only speculate as to why radioactivity is often illustrated as something glowing. One possible reason is that radioactivity is invisible, but dangerous. To make this danger visible in films or comics, radiation is shown as luminous – and usually green.
The green uranium fuel rod has figured prominently in each opening sequence of The Simpsons
In terms of volume, high-level waste makes up only around ten per cent of Switzerland’s radioactive waste. However, it is responsible for 99 per cent of the radioactivity and generates a lot of heat.
In contrast, low- and intermediate-level waste accounts for a much larger proportion of Switzerland’s radioactive waste.
That stuff in the yellow drums – occasionally yes...
Ninety per cent of Switzerland’s radioactive waste consists of low- and intermediate-level waste. Most of it comes from nuclear power plants: for example, as residue from water purification or as contaminated protective suits or tools. In addition, more waste is produced, or will be produced, during the dismantling of the nuclear power plants.
Medicine, industry and research also produce radioactive waste. The federal government is responsible for this waste.
Low- and intermediate-level waste generates less heat. In addition, most radioactive substances in this type of waste decay more rapidly. However, it still takes around 1,000 years for the radioactivity of most substances to decay to a harmless level.
What is the story behind the yellow drums?
Well, they do exist. However, they are just one out of a multitude of cask types in use. Not all radioactive waste ends up in the infamous yellow drum.
Most importantly: the image of loose drums out in the open will not apply to a Swiss deep geological repository. The drums are first neatly packaged into larger concrete containers and any voids are filled with cement mortar. Only then will they be emplaced in the deep geological repository.
Certain waste is incinerated at temperatures of up to 20,000 degrees Celsius in a plasma burner. Although this process does not reduce, let alone eliminate, the radioactivity, it significantly reduces the volume of the waste.
During incineration, glass is added to the molten waste. This creates a solid body of vitrified glass when it has cooled down, which is ideal for disposal. Another image that has become ingrained in many people’s minds is that of leaking liquids. In Switzerland, however, all the radioactive waste is solidified.
That green goo oozing from the drum definitely does not exist, which is, of course, a good thing.
Images: 20th Century Fox Television / ZWILAG interim storage facility / AI