Skip to main content
European Commission logo print header
Content archived on 2022-12-05

Natural analogue of the thermo-hydro-chemical and thermo-hydro-mechanical response of clay barriers

Objective



In many radioactive waste repository concepts, argillaceous materials have an essential role in ensuring long-term waste isolation. The isolation capacity of the clay barriers is estimated by means of models that eventually contribute to the performance assessment of the disposal system. In order to make a convincing case that the clay barriers will keep their effectiveness during the long term it is essential to understand their behaviour both under normal circumstances and under altered conditions. For repositories containg heat-generating waste, heating is a potential cause of alteration of the clay barriers. Laboratory and in situ tests provide information on short-term thermal effects and allow to simulate the initial evolution of any barier material. However the long-term behaviour of the repository or of specific barrier components cannot be obsened expenmentally.
Natural analogues have been recognized by the waste disposal community to be important for understanding long-term processes of relevance to waste isolation. In favourable circumstances natural analogues can be used also to calibrate/test the modelling of particular phenomena. Shortly the study of suitable natural analogues appears to be the only viable approach for confirming current knowledge and for testing models concerning the long-term behaviour of clays. It could also be the only opportunity to test mathematical models against physical realities on space and time scales comparable to those of nuclear waste repositories.
The heating caused by the intrusion of magmatic material into argillaceous sediments can be considered as the cause of conditions with analogies to the thermal effects of disposal of heat-generating waste in clays. Although not all conditions are precisely analogous in the geological sites and in the repositories, still useful insights could be drawn from the analogy. The overall objective of the present proposal is to identify natural analogues of the thermo-hydro-mechanical and thermo-hydro-chemical alterations of heated clays and to determine how applicable they are for studing performance assessment issues.
The work programme of the proposal is structured in such way that the general objective will be reached by pursuing six, more detailed objectives: - To identify the issues of concern for performance assessments of repositories for heat-generating waste in terms of the heating of the clay-based engineered barriers or host rock and the timescales involved.
- To review the literature to compile the information available relating to these issues and identify gaps in knowledge and uncertainties. - To consider what characteristics are required in a natural analogue site to study these issues unequivocally.
- To identify, where possible, analogue sites which seem to have these characteristics and review the data available for them and their validity. - To perform site evaluations at the most promising site(s) in order to scope exactly what may be achieved at each and to attempt to fill gaps in their datasets so that they may be used to test conceptual models. - To encourage collaboration among European radwaste disposal programmes in considering the identified issues.
Most of the work in the programme will be required for the characterization of the site and of the altered clays at one (or maybe two) location(s) which will be chosen after the reviews foreseen in the first year of the project. The site characterization will include field observations and laboratory determinations of clay properties.
In the end tha dataset developed for the study site should allow some form of model testing. The models that should be tested are expected to be developed in the framework of another project proposed within the Nuclear Fission Safety programme (T-H-M-C Clay Barriers Project).
The project has four partners, with the possibility of additional organizations coming in at a later time once the study site has been selected. On the contrary IPSN, the French participant, has already indicated the intention to subcontract some of the characterization work to the company E.R.M. Poitiers and to "I'Ecole des Mines de Paris".
The total budget of the project is estimated to be kECU 1002. The amount requested to EC is kECU 546. The request exceeds 50% due to the university participant (Rome University) applying for marginal costs.

Call for proposal

Data not available

Coordinator

Enel.Hydro SpA
EU contribution
No data
Address
9,Via Pastrengo
24068 Bergamo - Seriate
Italy

See on map

Total cost
No data

Participants (4)