1 National Waste Classification and Policy
1.1 Classification
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 (4 gigabecquerels (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.
1.2 Policy
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.
2 Approach 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 and Radioactive 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.
3 Details of Planned Disposal Facilities
3.1 Disposal 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 sets out 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.
3.2 Waste 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 458,000 m3.
3.3 Geological 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 used to 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
space is 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
Figure 1 Multi-barrier approach to ILW disposal in the UK,
showing the safety functions of the various engineered and
natural barriers.
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.
https://www.nda.gov.uk/ukinventory/documents/upload/2013-UK-Radioactive-Waste-Inventory-WasteQuantities-from-all-Sources.pdf
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 www.nda.gov.uk
v Nuclear Decommissioning Authority, Geological Disposal, Generic Disposal Facility Designs, NDA
Report No. NDA/RWMD/048, December 2010