Nuclear Waste

Hundreds of thousands of years in the future, when even the pyramids have been ground to dust by wind, one human structure on Earth will remain.

At least that’s the plan for Onkalo, a building under construction right now in Finland. If successful, it may be one of the final artifacts of human civilisation.

If we look back at history, any attempt at creating something so long-lived, like the Pyramids, Stonehenge, or Easter Island’s statues, usually had some religious significance. But Onkalo is much more mundane.

It’s the world’s first permanent nuclear waste storage site.

This is surprising for a couple of reasons. First, why is it so important to build a storage site that will outlive our civilisation? Second, how can it be the first permanent nuclear waste storage site? Haven’t we been using nuclear power for decades?

Let’s jump in and find out.

The amount of effort that’s going into Onkalo could be seen as symbolic of the unique times we live in. Specifically, about our waste.

We make 2.6 trillion pounds of it each year, weighing more than 7,000 Empire State Buildings. We’re on track for there to be more pounds of plastic in the oceans than pounds of fish by 2050.

It follows that waste is one of our most enduring effects on the planet, and as our technology and standard of living improve, the more we seem to produce.

But of all our waste, the nuclear variety is by far the longest-lived. One type is called ‘plutonium-239’, and it’s a product of most nuclear plants. One thousand tons of it is currently in storage, with twenty additional tons being added each year as the plants operate.

Nuclear power has many advantages as an energy source, but its creation of plutonium-239 is not one of them. Its toxicity is similar to that of nerve gas, and the accidental inhalation of just one-millionth of a gram of its dust would give you cancer. A single pound of it is enough to kill 2 million people.

Once it’s been made, it takes over one hundred thousand years to degrade.

Let’s spend a moment on why nuclear waste like plutonium is like it is, and why it’s dangerous.

Fundamentally it’s an atom that’s unstable.

Either it’s too big, or has an unbalanced ratio of protons to neutrons. The atoms ‘decay’ which means they shed protons, neutrons, and other forms of radiation until their atoms are small enough to be stable again.

This can take anywhere from seconds to millions of years.

It’s possible for radioactive substances to occur naturally, but most of it on Earth is man-made.

We make it as a byproduct of nuclear fission, where we break apart atoms to access the energy inside and use it for electricity and bombs.

One of the first researchers into radioactivity was Marie Curie, the first woman to receive a Nobel Prize.

Unfortunately, she didn’t realise that her radioactive materials were killing her while she worked.

Radiation strikes and kills our cells, or alters their internal molecules like DNA.

In Marie’s case, it killed the irreplaceable cells inside her bone marrow, which stopped her body’s ability to make blood. She slowly died of aplastic anemia.

Nowadays we have a much better understanding of what radiation can do and are much more careful. Marie Curie’s notebooks for instance, which are over 100 years old and still radioactive, are stored within a dense, lead-lined box in a museum.

We now know that if radiation strikes the wrong spot in our DNA, it can change fundamental instructions in our cells, such as when a cell should start and stop replicating.

As a consequence, the cell may start replicating out of control, with every new cell inheriting the same faulty instructions.

Before long, it makes a dense clump called a tumour, which (in some cases) can break apart and form new tumours around the body. If you haven’t guessed, this disease is cancer.

We also know that not all types of radiation are bad. It’s often used in medicine to diagnose internal problems. But these are different types of radiation that are much lower energy, break down within a few hours, and do no damage to the body. A doctor is unlikely to use plutonium to diagnose our broken bones.

Back to the Onkalo storage facility.

A lump of Plutonium-239 takes over 100,000 years to sufficiently decay, which is a really long time. What do we do with a substance that is so toxic, yet lives for so long? For some perspective, the pyramids are ‘just’ 5,000 years old.

100,000 years ago, our distant Homo Sapiens ancestors had not yet left Africa, and the area around the Onkalo facility was inhabited by an entirely separate species of human, Homo Neanderthalensis.

No one really knows what it will look like in another 100,000 years.

What do we do with a substance that remains toxic on timescales so far into the future, that by the time they’ve decayed, humans might have  split into new species?

For the most part, the answer is we don’t know.

All of the nuclear waste that we have ever produced, including our thousand tons of plutonium, is currently in “temporary storage until a permanent solution is found”.

Many of these temporary storage facilities are not designed to last more than thirty years, and are nearing or have past their expiration date.

The one exception is the nuclear waste that’s being made in Finland, who is also building the world’s first permanent nuclear waste storage facility. Onkalo.

The plan is to bury it deep within the Earth, in a place where there is very little geologic activity, and where not even the glaciers of a distant future Ice Age can disturb it.

The wildcard, and the biggest risk of the site being disturbed, is future human beings.

No matter how well disguised Onkalo is, a clever person will be able to tell that it’s different from the surrounding landscape, even far into the future.

So the Finnish government has decided that a message has to be left for these people. They have to find a way to warn them to stay away, but without making them even more curious.

Not an easy task when any language is almost certain to be unrecognisable to them.

A few ideas have been proposed. One was to build a forbidding landscape of concrete spikes to create the impression that the area is unwelcoming and dangerous.

Anyone who has seen the Lion King knows this just makes an awesome place to hang out.

One unusual idea was to genetically engineer a species of cats to glow when radiation is present, and release them in the area. Hopefully, people would be frightened of the descendants of the strange animals and stay away.

But who wouldn’t be interested in the place that makes the cats glow?

Unfortunately there is no definitive answer on what form a message should take.

But for when we do work it out, Academics at Sandia National Laboratories have decided what the message should say.

They composed this chilling passage for the people of the distant future. It reads:

This place is not a place of honor… no highly esteemed deed is commemorated here… nothing valued is here. What is here is dangerous and repulsive to us. This message is a warning about danger. The danger is still present, in your time, as it was in ours. The danger is to the body, and it can kill. The form of the danger is an emanation of energy. The danger is unleashed only if you substantially disturb this place physically. This place is best shunned, and left uninhabited.

It’s a haunting message for what may be humanity’s longest lasting legacy.