1National Waste Classification and Policy
1.1Classification
In the UK, radioactive wastes are classified according to the type and quantity of radioactivity they contain and how much heat is produced.
Intermediate level waste is defined as waste having a radioactive content exceeding the upper boundaries for low-level waste (4gigabecquerels (GBq) per tonne of alpha, or 12 GBq per tonne of beta/gamma activity)but which does not require heating to be taken into account in the design of storage or disposal facilities.
It is part of a classification of Higher Activity Waste (HAW), which comprises a number of categories of radioactive waste – high level waste (HLW), intermediate level waste (ILW), and low level waste (LLW) that is not suitable for near-surface disposal in current facilities.
1.2Policy
UK policy on radioactive waste management requires wastes to be managed and disposed of in ways which protect the public, workforce and the environment both now and in the future: i.e. that management aims to process wastes into a passive form and to take into account the impact of today’s activities on future generations. Radioactive waste management is a devolved issue, meaning that the UK government has responsibility for the policy in respect of England, and the Welsh Government in respect of Wales, the Scottish Government in respect of Scotland, and the Northern Ireland Executive in respect of Northern Ireland.
2Approach to managing ILW
UK government policy for managing higher activity radioactive waste in England in the long-term is through geological disposal, which will be implemented alongside ongoing interim storage and supporting research. The planning basis for geological disposal of ILW is for co-disposal with other HAW andRadioactive Waste Management Ltd is responsible for implementing the long-term solution for managing HAW.
The preferred option in Scotland for the long-term management of ILW is in near-surface facilities, with facilities being located as close as possible to the sites where the waste was generated. An implementation strategy for Scottish wastes is planned to be developed in 2015. The Welsh Government is currently consulting on its approach. The Northern Ireland Executive supports the implementation of geological disposal for the UK’s higher activity radioactive waste.
3Details of Planned Disposal Facilities
3.1Disposal option and timescales
Siting of a geological disposal facility is at an early stage. In July 2014, UK government published a White Paper[[i]] which setsout a revised policy framework for implementing a voluntarist approach to implementing geological disposal, based on working with communities that are willing to participate in the process to identify potential sites.The formal process of working with communities is expected to begin in 2016.
3.2Waste characterisation and volume
The UK has a large and diverse inventory of ILW, arising mainly from the reprocessing of spent fuel and from general operations, maintenance and decommissioning of radioactive plant.Over the lifetime of the UK’s existing nuclear facilities, the greatest proportion of higher activity waste will be graphite and contaminated metals from the core of nuclear reactors. The 2013 UK radioactive waste inventory [[ii]] shows that the total committed (i.e. current and future) reported volume of ILW is about 286,000 m3. When packaged for disposal, this will rise to 458,000m3.
3.3Geological Disposal facility design including engineered barrier system design
The UK has a diverse geology and there is a large range of potentially suitable geological settings, and no single ‘best’ or ‘most suitable’ generic type of geology for a geological disposal facility (GDF). In the absence of a known location – and therefore a known geology - for a UK GDF, three generic geological settings have been defined for planning purposes. These aim to represent a range of possible host rock formations and associated geological and hydrogeological conditions present in the UK. These three settings are higher strength rocks (e.g. granite), lower strength sedimentary rocks (e.g. clay) and evaporites (e.g. anhydrite and rock salt).
Illustrative ILW disposal concepts for these host rocks [[iii]],drawn from studies carried out in the UK and elsewhere [[iv]], have been used to develop generic GDF designs which accommodate the UK inventory[[v]].These designs are usedto help understand the basis of safety and the relevant environmental, social and economic impacts.In all the designs ILW containers are stacked in excavated vaults and the remaining excavated spaceis backfilled.
A UK geological disposal facility will use multiple engineered and natural barriers to isolate radioactive waste form the surface environment and contain the radioactivity. For ILW, the engineered barrier system (EBS) will involve immobilising the waste into a passive form (typically grout), placing it within a container (typically stainless steel) and backfilling with cement., The geological environment forms a natural barrier to provide the required isolation from the surface environment and also contributes to containment by protecting the engineered barrier and retarding any radionuclides which move beyond the engineered system in groundwater or in gas. This is illustrated in Figure 2.
[i]UK Government Department for Energy & Climate Change and the devolved administration of Northern Ireland, Implementing Geological Disposal: A Framework for the long-term management of higher activity radioactive waste, White Paper July 2014
[ii] UK Government Department of Energy & Climate Change, Nuclear Decommissioning Authority, 2013 Radioactive Inventory: Waste Quantities from all Sources.
[iii]Nuclear Decommissioning Authority, Geological disposal: Steps towards implementation, NDA Report NDA/RWMD/013, 2010
[iv] T.W. Hicks, T.D. Baldwin, P.J. Hooker, P.J. Richardson, N.A. Chapman, I.G.McKinley and F.B. Neall, Concepts for the Geological Disposal of Intermediate-level Radioactive Waste, Galson Sciences Limited Report to NDA-RWMD, 0736-1, 2008. Available at
[v] Nuclear Decommissioning Authority, Geological Disposal, Generic Disposal Facility Designs, NDA Report No. NDA/RWMD/048, December 2010