Finland to begin filling giant nuclear waste tomb in 2020

7 Jun 2016

One of the Onkalo tunnels. Image via Posiva

After decades of running nuclear power plants, Finland is preparing to bury thousands of tonnes of nuclear waste in 2020 in what is being described as the costliest tomb in history.

With a number of countries moving away from nuclear energy in favour of cleaner, renewable energy, the question of what to do with the remaining nuclear waste remains complicated.

In Finland, however, where there have been nuclear power stations since the 1950s, the country is finalising a massive construction project to bury 5,500 tonnes of nuclear waste below ground, where it will stay radioactive for more than 100,000 years.

According to AFP, Finland will begin placing its radioactive waste in the world’s costliest and longest-lasting burial ground, called Onkalo, which, in Finnish, means ‘The Hollow’.

Having begun construction in 2004, the tunnel system will stow the waste 420m beneath the Earth’s surface, with the project expected to cost the Finnish government up to €3.5bn.

42km of tunnels

While a stretch of 5km of tunnels has been constructed so far, when the system is completed it will eventually stretch up to 42km in length, where the spent nuclear rods will be placed in iron casts before being sealed again in thick copper canisters.

Even further protection from the elements will be aided by a buffer made from bentonite that will help prevent water leaking in or any movement in the surrounding bedrock.

The first nuclear waste shipments will begin entering the tunnels in 2020 following construction and, if all goes well, no human will set foot in them for eons to come.

The only difficulty with working under such a grand timeline, however, is trying to predict what the environment will be like in 100,000 years’ time?

Onkalo construction

A diagram of Onkalo once it’s constructed. Image via Posiva

Predicting the far-future

During planning, the engineers had to take into account the possibility of a new ice age at some point, which has led to the Finnish nuclear safety authority, STUK, demanding more modelling from the construction company on the possible long-term effects of such a freezing event.

One particular worry is that a 2015 study conducted by the Finnish University of Turku said that, should a new ice age occur in the region, the permafrost could reach depths 200m below where the waste will be buried.

Another fascinating question to ponder is whether warning signs should be erected, as a sign that may mean something now might mean absolutely nothing – or something different entirely – in 100,000 years.

Taking the example of the excavation of ancient Egyptian tombs, Ismo Aaltonen, chief geologist and nuclear waste manager of the project, said: “There are examples like in Egypt, where a curse was to fall upon the person who passed a certain door and, of course, people just entered there.”

Colm Gorey was a senior journalist with Silicon Republic