Fresh fears raised over viability of underground repository for nuclear waste

Build up of gases could damage structure or vent radioactive isotopes

Concerns have been raised again over the viability of a deep geological repository for storing nuclear waste because of the build-up of gases within such a chamber. 

Experts believe that gases generated by metal corrosion and degradation of organic waste would be likely to accumulate within a geological repository. The main gases produced would be hydrogen, carbon dioxide and methane. It is thought these could contain radioactive isotopes such as tritium and carbon 14. 

If gas accumulated within a repository there would be a build-up of pressure which could have an effect on the repository’s engineered structure and host rock, some believe. 

Peter Wilkinson of Nuclear Waste Advisory Associates said there were “anomalies” in terms of the development of a repository that still needed to be addressed. “On the one hand you have to isolate the radioactivity from the biosphere in a repository, and therefore you want to make it as impermeable as possible, but on the other you need to ensure that some of this gas escapes.

“It’s a dilemma. If gas is vented, it could significantly alter the risk of those exposed to developing fatal cancers,” he said.

The Environment Agency is working with the Nuclear Decommissioning Authority (NDA), the body responsible for developing the repository, to identify the “significant technical issues” surrounding the build-up of gases. The NDA said it was continuing to work with it on the issues surrounding the potential development of a geological repository. The Environment Agency first expressed its concerns about gas build-up within a repository in a report published in 2008.

According to the 2008 report, “the modelling of gas and its effects [within a repository] continues to present many challenges”.