Fluid flow in excavation damage zones of a nuclear waste facility

Developing solutions for safe nuclear waste disposal
Fracturing and spalling of the Opalinus Clay in the Mont Terri Underground Research Laboratory, Switzerland

Fluid flow in excavation damage zones of a nuclear waste facility

Developing solutions for safe nuclear waste disposal
Title: Fluid flow in excavation damage zones of a nuclear waste facility
Funded by: Nuclear Waste Services
Dates: October 2023 – November 2027
Project partners: University of Hull 
The project investigates the properties of the Mercia Mudstone, a candidate host rock for the UK’s deep geological repository. It specifically focuses on how rock properties can govern the flow of fluids within excavation-induced fractures, which has implications for waste container corrosion and radionuclide transport.
This PhD research project at the University of Plymouth is sponsored by Nuclear Waste Services
 

Project objectives

  • Characterising the nature and extent of macroscale Excavation Disturbed Zone (EDZ) propagation in candidate GDF host rocks using analogues at UK locations.
  • Developing a new testing apparatus to explore the behaviour of microscale deformation features and geochemical interactions in rocks using rock core in the laboratory.
  • Using the new testing apparatus, explore the implications of EDZ evolution on near-field fluid flow in space and time.
  • Creating conceptual models which capture key controls on EDZ formation and evolution to support numerical representations and safety assessments.

Disposal of our most hazardous nuclear wastes is a critical enabler for new nuclear power. The UK has recently identified candidate sites deep below the seabed in the North East Irish Sea, however our understanding of fluid flow through these rocks is at an early stage. It is critical that we fully understand the properties of the rock which will contain the wastes, in order to guranatee wastes remain effectively contained for generations to come.

Matt BaileyDr Matt Bailey
Associate Professor in Engineering Geochemistry

 
Deep, geological disposal of radioactive waste will contain and isolate these hazardous materials, protecting people and the environment for generations to come.  To fulfil this objective, geological disposal is reliant upon a combination of engineered and natural (rock) barriers to prevent the movement of radioactive substances.  Disturbance of a rock-mass during construction of tunnels and underground vaults can alter the properties of this natural barrier, for example by the formation of fractures within the rock through which water and gas can flow.

This project will explore how excavation disturbance might impact the properties of potential host rocks for the UK’s facility, to better understand how these fractures will develop and change over time and, how this will impact the flow of water and gas.  We will use similar ‘analogue’ scenarios, such as road cuttings and cliff exposures to investigate the effect of disturbance on the rock, as well as developing new laboratory experiments on rock samples to explore this at a smaller scale.  We will develop a conceptual model to explain the mechanisms of excavation disturbance to allow it to be accounted for in safety assessments.

Centre for DecarbOnisation, Resilience and Energy Systems

We bring together leading researchers from across the University of Plymouth to develop innovative solutions to the national and global challenges of decarbonising energy systems, strengthening resilience to climate change and security risks, and supporting sustainable economic growth.
Centre for Decarbonisation and Offshore Renewable Energy