What is it about?
It is likely that radioactive wastes will be placed in an underground geological disposal facility. Such a facility will be dry during its operational phase but will likely become saturated with groundwater after closure. Extensive use of concrete will form part of the engineering of the facility. Once re-saturated with groundwater this will create a highly alkali (high pH) environment. Dissolved organic carbon is the brown discolouration you see in streams draining peat moorland and is the product of the decay of once living plants and organisms (the tannic acid that makes your black tea is another example). This organic carbon is present in all groundwaters and is an important chemical in the mobility of dissolved metals - including radioactive elements. This study reviews the currently available science relating to interactions between dissolved radioactive metals and organic carbon in high pH environments.
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Why is it important?
Once closed a geological disposal facility will be saturated with groundwater and the interaction with concrete will create a high pH environment. In order to robustly predict radioactive element behaviour under different safety scenarios we need experimental data on the interactions with organic carbon.
Perspectives
These processed should be considered in terms of the multiple levels of containment that will be used in a geological disposal facility. So there may be encapsulation of the waste in glass or concrete, a container, and packing of clay surrounding a container, as well as the engineering of the facility and the surrounding host rock. This creates multiple layers, so transport of the waste away from the facility in groundwater and potentially enhanced by organic carbon is very much a worst case scenario. We perform these studies so academics and industry can more accurately predict the effects of such extreme containment failure and build these into Risk Assessments and Safety Cases. Regardless of the future direction of nuclear projects within the UK, we have no choice but to deal with our complex legacy of radioactive wastes, built up over decades of nuclear weapons and nuclear power development. The UK needs to urgently embark on a programme of public engagement so the veil of secrecy can be removed and we can as a nation move to a greater understanding of the legacy that we and previous generations have created and how we can constructively deal with this.
Anthony Stockdale
Read the Original
This page is a summary of: The influence of natural organic matter on radionuclide mobility under conditions relevant to cementitious disposal of radioactive wastes: A review of direct evidence, Earth-Science Reviews, June 2013, Elsevier,
DOI: 10.1016/j.earscirev.2013.02.007.
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