From its inception the nuclear industry has relied upon science and mathematics to help solve its problems. Quintessa continues this tradition within a 21st century context through our world-class consultancy, research and software capabilities.

Provision of Expert Support to STUK

Quintessa is providing expert support to the Finnish Radiation and Nuclear Safety Authority (STUK) for the review and assessment of the construction licence application for the Finnish KBS-3 repository for spent nuclear fuel which is planned to be constructed at Olkiluoto.

The support is provided in two areas: the first is the post-closure safety analysis of the disposal system, in particular the review of the analysis of radionuclide transport from the repository to the biosphere. The review... Full Details

Updating the NEA’s Features, Events and Processes (FEP) Database

The Nuclear Energy Agency (NEA) first published a Features, Events and Processes (FEP) list for geological disposal of radioactive waste in 2000. It is currently being updated by the FEP Task Group of the NEA’s Integration Group for the Safety Case. It is envisaged that the final product will be a web-based database that is relevant to both safety assessors and individual topic experts, to all designs of geological disposal facilities, and to all categories of radioactive waste in geological disposal facilities. It is anticipated that the database will be available in 2015. Full Details

CABARET Geochemical Modelling Software

CABARET (Cement And Bentonite Alteration due to REactive Transport) is a GUI-driven software package developed by Quintessa for simulating reactions between cementitious materials and bentonite in multiple dimensions.

CABARET allows users to specify cement-bentonite-rock-water systems flexibly, in terms of the chemical components present, the physical geometry of the simulated system and the processes to be represented. Chemical and transport processes can be fully coupled to one another so that, for example... Full Details


Since 1992 the international DECOVALEX (DEvelopment of COupled models and their VALidation against Experiments) research project has been at the forefront of advancing the understanding of coupled thermal-hydrological-mechanical-chemical (THMC) processes in support of the safe geological disposal of radioactive wastes.

Quintessa is participating in the current phase (DECOVALEX-2015) on behalf of the Nuclear Decommissioning Authority (NDA) Radioactive Waste Management Directorate (RWMD) as part of a project on coupled... Full Details

Land Contaminated by Accidental Releases of Radioactivity from Fukushima Daiichi

The Tohoku earthquake and tsunami of 2011 resulted in a major nuclear accident at the Fukushima Daiichi Nuclear Power Plant. Radioactive releases occurred to the atmosphere and contamination was found in land within and beyond the exclusion zone set up around the site.

In the aftermath, the Japan Atomic Energy Agency (JAEA) advised on accident recovery actions, including remediation options for contaminated locations. Quintessa provided support to JAEA by developing an... Full Details

Potential for Buoyant NAPLs to Migrate in the Free Phase from a Geological Disposal Facility

A safety case for the disposal of intermediate level waste (ILW) in a deep Geological Disposal Facility (GDF) requires consideration of the potential for a discrete light non-aqueous phase liquid (LNAPL) to form in disposal vaults, and the subsequent potential impact that might arise. A team from AMEC, Quintessa and the University of Birmingham has recently completed a study for the Nuclear Decommissioning Authority (NDA) Radioactive Waste Management Directorate (RWMD) that developed and documented a series of long-term safety arguments concerning NAPLs in a GDF containing Intermediate Level Waste (ILW). Full Details

Understanding the Post-Closure Thermal Impact of HLW/SF Packages

Knowledge of the maximum temperature reached at any point in the disposal system and the time period over which the temperature is predicted to exceed certain threshold values is an important input into a number of decisions regarding disposal concept selection and subsequent facility design. Quintessa has recently completed a study for the Nuclear Decommissioning Authority Radioactive Waste Management Directorate (NDA RWMD) that aimed to identify the key controls on the thermal performance of the High Level Waste / Spent Fuel (HLW/SF) disposal area of a UK Geological Disposal Facility (GDF) during the post-closure... Full Details