DECOVALEX is an industry leading collaboration between radioactive waste management organisations, regulators, consultants and research institutes to build understanding in modelling complex coupled thermal-hydraulic-mechanical-chemical processes (THMC).  Running since 1992 the project is going from strength to strength now with 18 funding organisations, 8 diverse and challenging tasks and over 60 research teams. 

Quintessa is pleased to be involved in DECOVALEX for a fifth consecutive phase, through work funded by Nuclear Waste Services (NWS) and providing Technical Coordinator services to the whole DECOVALEX-2027 project. Quintessa employees attended both in-person and on-line, with those attending in-person giving three presentations at the workshop.

• Steven Benbow presented work by himself, Kate Thatcher and Louise Bruffell on the BaSiSS:  Bentonite and Sand in Sealing Systems task, funded by NWS. The task considers advective movement of water and gas in sand/bentonite mixtures with high sand content, which are proposed as seals in disposal facilities and are designed to manage gas pressure to protect the integrity of lower strength sedimentary rocks. To date, the modellers have represented coupled hydro-mechanical models including bentonite swelling and deformation for a laboratory experiment and will move on to apply models at the field-scale.
• Neil Chittenden presented work by himself, Josh Nicholas and Claire Watson on the HyMAR: Hydro-Micromechanics of Argillaceous Rocks task, funded by NWS. The task considers the processes that govern damage of lower strength sedimentary rocks and the influence of this damage on gas and water migration. To date, the modellers have worked on constitutive models to represent post-elastic behaviour observed in laboratory experiments and will also move on to apply the models at field scale.
• Alex Bond presented Quintessa-funded work by Josh Nicholas and Steven Benbow on the PA Salt task, showing their completed whole repository modelling, which includes fully coupled multiphase flow, tunnel convergence, hydrogen gas generation and radionuclide transport. Alex also presented work on a highly localised model looking at the same process set, but also includes localised salt redistribution and vapour transport in order to examine localisation effects that are of relevance to the whole-repository model configuration. Both models are implemented in Quintessa’s general-purpose modelling tool, QPAC.

Alex Bond is the Technical Coordinator for the whole DECOVALEX-2027 project, focussing on supporting the task leaders in delivering the best output for their tasks, as well as taking an overview of all the technical work being produced in the project.  Alex is funded centrally through contributions from all of the DECOVALEX funding organisations and will be working closely with the project Chair, Jens Birkholzer.

We very much enjoyed participating in the 4th Workshop. Those who travelled to Berkeley enjoyed visiting the Berkeley Advanced Light Source (ALS) and Geosciences Measurement Facility (GMF). There was also a whole-day visit to the LBNL NUMO field site which supports in-situ borehole monitoring of the San Andreas Fault zone. This was followed by visits to the San Juan Bautista mission where the fault scarp from the 1906 earthquake can be viewed, and the DeRose Vineyard where shear deformations from recent earthquakes are visible. We very much thank LBNL for their hospitality and look forward to future DECOVALEX workshops.