A description of Onkalo, the Finnish GDF – a burial site for nuclear waste

In his recently published book, Underland, Robert Macfarlane describes in great detail the Finnish approach to burying its inventory of nuclear waste, and the need to warn future societies to avoid reopening the facility for hundreds of thousands of years. That is a remarkably complex problem, as Robert illustrates.

The author is also reassured by his Onkalo guide that copper is the ideal material from which to build canisters to contain the spent fuel. There is an increasing amount of evidence which suggests that copper performs much less well than expected.

Specifically, the assumption that copper will not corrode without the presence of oxygen (which is consumed by bacteria and chemical processes soon after emplacement) has been shown to be false. A pitting process works its way through the copper surprisingly quickly in anoxic environments. The Swedish Environmental Court halted Sweden’s repository licence over these concerns in 2018, requiring more detailed information before it reconsiders. It is far from clear that this KBS-3 copper encapsulation method is safe, despite the reassuring words of the Onkalo guide.

The UK is planning to use the same encapsulation method, and despite all the talk of openness and transparency, the standard approach of the Nuclear Decommissioning Authority and its subsidiaries is to deny or minimise the existence of problems until they are forced to admit them.

Onkalo appears to be a positive example of how a GDF should be planned and constructed. The excerpt from Underland provides a fascinating insight into the project and should be of interest to Cumbria Trust’s members.

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