Deep geological disposal of nuclear waste

A geological disposal facility (GDF) for Britain’s nuclear waste is a much-needed item of infrastructure that will put the contents of Sellafield, and some 25 other sites around the UK where higher activity nuclear waste is temporarily stored, deep underground forever. By doing so a GDF will remove the intergenerational burden of cost (£3.3 Billion in 2025/26, some 75% of which was met by the taxpayer) and ensuring that the stored waste is permanently secure .

To give you a feel for deep geological disposal projects in the UK and internationally here are slide packs I used for presentations to:

Geo-Energy Conference, Aberdeen, May 2023

Birmingham Schools Science Network, Birmingham, November 2022 (full presentation here)

The Geological Society, London, February 2019 (full presentation here)

Delivering a GDF is primarily a social challenge and nuclear waste organizations devote considerable effort to providing the public with high quality information on what a GDF looks like, what goes in it and how it is designed to protect people and the environment from harmful radioactivity for 100,000s years. Given the critical importance of selecting suitable geology in which to construct a GDF, Nuclear Waste Services produced a range of educational videos including ‘on location’ descriptions of host rock types, rock structure, faulting and folding.

The ‘OPERA’ safety case 2018 is the best example I’ve seen of a publicly accessible generic safety case for a GDF, produced by COVRA (Centrale Organisatie Voor Radioactief Afval) the Netherlands nuclear waste disposal company. It outlines the origin and nature of the radioactive waste, and how a GDF will be designed and built to ensure that the waste will be sealed deep underground for 100s thousands years to protect humans and the environment from its harmful effects.

Our free-to-download 2023 journal paper provides a peer reviewed overview of the science, engineering and policy challenges of selecting a site for deep geological disposal of the UK’s radioactive waste stockpile. It is based on this presentation I gave at a conference organized by the Yorkshire Geological Society, September 2021.

“In 2018 when I first visited Olkiluoto island – the site of the Finnish nuclear waste repository on the Baltic coast – I and my Nuclear Waste Services colleagues noted wryly that in the 1990s the UK and Finland were level pegging in the progress we were making on selecting a site for a geological disposal facility (GDF). Roll on 30 years and Posiva, the Finnish nuclear waste management organization, commences waste emplacement in the world’s first higher activity nuclear waste GDF this year; the UK is still on the starting blocks with no suitable geology nor willing host community yet identified.”

Why is progress so slow in identifying a GDF site for the UK? I argue in this Viewpoint article written for The Geological Society’s Fellows’ magazine Geoscientist that UK government needs to abandon the process of voluntary community consent and prioritize technical considerations, particularly geology. And here is an expanded version published in The Geologists’ Association members’ magazine, December 2025.

These articles refer to Colin Knipe’s comprehensive assessment of the subsurface investigations at Longlands Farm that formed an appendix to the Inspector’s Report (1996) to the Secretary of State, and which contributed to the cancellation of further development of an underground rock laboratory at Sellafield. It gives a flavour of the high bar that regulators set for characterizing the host rock geology in which a GDF will eventually be constructed.

In March 2026 The Times reported that Nuclear Waste Services (NWS) are applying for the necessary permissions to use deep borehole drilling to investigate the suitability of the Mercia Mudstone Group beneath the Irish Sea as a GDF host rock. Deep boreholes are very expensive and will require local and regional buy-in as well as assurance they can deliver good value for public money. Long before boreholes are drilled NWS will therefore need to make public what has been learned about the MMG from the 250 square kilometres 3D seismic survey they acquired offshore the Sellafield area in August 2022 at a cost of £17 Million.

Four years is an unprecedentedly long period for publicly funded subsurface information such as seismic data to be kept under wraps. Since the start of 2026 I have been pursuing a Freedom of Information request to obtain access to NWS’ reports on their southern Irish Sea seismic data. So far without success, I am now seeking a resolution through the Information Commissioner’s Office.

I anticipate that when the findings from the seismic data are exposed to wider scrutiny many of the same challenges as were encountered with the Borrowdale Volcanics Group at Longlands Farm in the 1990s will resurface, particularly the MMG’s highly variable (heterolithic) nature on scales of centimetres to kilometres. Heterolithic geology is inherently unpredictable, but predictability will be the regulators’ primary requirement for sanctioning a potentially suitable GDF host rock.

The photo here shows low-activity nuclear waste disposal operations at the ERAM repository constructed inside a Permian salt diapir at Morsleben, Germany.

Courtesy: Bundesgesellschaft für Endlagerung mbH