Quintessa is participating in the EC 6th Framework Programme Integrated Project (IP) NF-PRO with financial support from the EC and Nirex. NF-PRO is concerned with the understanding and physical and numerical modelling of key processes in the near-field of high-level waste (HLW) and spent fuel (SF) repositories in crystalline, clay and salt geologies.
The main objective of NF-PRO is to establish the scientific and technical basis for evaluating the safety function "containment and minimisation of release" of the near-field. To this end, NF-PRO is studying the dominant processes as well as the process couplings affecting the isolation of nuclear waste within the near field and is developing and applying conceptual and mathematical models for predicting the source-term release of radionuclides from the near-field to the far-field.
To understand the performance of the overall near-field system, an adequate insight in both the performance of the individual near-field sub-systems and their interactions is essential. Accordingly, NF-PRO has been structured in four Research and Technology Development Components (RTD Components) each representing a major near-field sub-system. In particular, RTD Components 1 to 4 address key processes controlling dissolution of and release from the waste matrix, chemical processes taking place in the EBS, the thermo hydro-mechanical evolution of the EBS and the characteristics and the evolution of the excavation disturbed zone, (EDZ) respectively. Process couplings and integration in performance assessment are dealt with in RTD Component 5. RTD Component 6 brings together all activities concerning knowledge management and transfer (including training).
Quintessa is participating in Component 2 (WP2.6) and Component 5 (WP5.1).
In WP2.6, Quintessa is modelling the outcome of experiments on the chemical evolution of bentonite being performed in WP2.1 to WP2.5. Quintessa is making use of the Raiden fully coupled reactive transport model for this purpose. The first application within NF-PRO relates to the interaction of cementitious water with bentonite.
In WP5.1 Quintessa is developing and applying a system-level model for the coupled evolution of a near-field disposal cell, for both iron-based and copper based containers. A key feature of NF-PRO is that is evaluating the realistic evolution of the near field in contrast to many other projects where pessimistic assumptions are made. For example, many performance assessments of HLW/SF in iron canisters have assumed that the canister 'disappears' at a given time. This is clearly unrealistic, but is often claimed to be conservative. A schematic view of chemical evolution of the bentonite buffer from the internal and external boundaries to be included in the model is shown below.
For more information please contact David Hodgkinson.