Performance Assessments


The Performance Assessment (PAS) Unit evaluates the long-term safety of radioactive waste disposal facilities based on modeling radionuclide release from a multi-barrier disposal facility into the geosphere and dispersion in the geosphere towards the biosphere. This includes aspects of scenario development based on integration of phenomenology knowledge, development of safety models, FEP-analysis, uncertainty management, simulation studies for justification of safety model assumptions and development of safety arguments for a safety case.

PAS therefore strongly invests in the conceptualization, the development of coupled numerical models and the parameterization for both engineered barriers and groundwater systems to be able to analyze the evolution and the interaction between different components both in engineered and natural systems at time and spatial scales relevant for long-term performance  and safety assessments.

Main activities

Performance Assessment

Performance Assessment – Development of a general framework for safety and performance assessment of surface and geological radioactive repositories:

  • Development of safety strategies and argumentation
  • Scenario development including FEP, uncertainty management, etc.

HydroGeoSphere research

HydroGeoSphere research with focus on transport processes in soil and aquifer systems:

  • Flow and reactive transport in unsaturated (soil) systems
  • Earth surface evolution and subsurface evolution to study temporal and spatial variation of properties and boundary conditions
  • Hydrogeology to develop and validate site-specific groundwater flow and transport models

Near field and engineered barriers research

Near field and engineered barriers research with focus on transport processes in repository components with an important safety function including the interaction and the evolution between and of these components or the system as a whole:

  • Development, verification and application of conceptual and mathematical models for the evaluation of long-term evolution of barriers in a disposal system
  • Development, verification and application of conceptual and mathematical models for radionuclide migration through engineered and natural barriers
  • Coupled temperature-hydrological- chemical –mechanical (THCM) model development and applications

Mathematical tools

Development and application of mathematical tools for advanced inverse optimization and uncertainty/sensitivity analyses.


Studies for (near)-surface disposal facilities

cAt project: studies for the near-surface disposal facility for low level and intermediate-level short lived (LLIL-SL) waste (category A waste) at Dessel (Belgium)

Studies for geological disposal facilities

The main activity is related to the Belgian geological disposal program for intermediate-level long lived and high-level radioactive waste

Head of Unit: Jacques Diederik