Current projects

EPSP Experiment – operation in 2024

Duration: 2020-2026

Recipient: Faculty of Civil Engineering CTU

DOPAS comprised an extensive European-wide project in which the Faculty of Civil Engineering of the Czech Technical University, ÚJV Řež, a.s. and SÚRAO participated on behalf of the Czech Republic. The aim of the Czech participation in the project concerned the construction of an experimental pressure and sealing plug (EPSP) in the granite rock mass of the Josef gallery. Sealing plugs will serve to separate the filled and unfilled disposal spaces in the future Czech DGR. The EPSP experiment was constructed in the middle of 2015. The construction of the plug itself confirmed that the technologies and materials used are suitable for application in the future DGR. The construction of the plug was accompanied by the installation of the monitoring system – approximately 250 sensors were installed in the experiment and the surrounding rock.

In order to verify the functioning of the plug, it was necessary to conduct the experiment over a relatively long period; hence the testing of the EPSP continued after the end of the DOPAS project. The experimental activities related to the pressurisation of the plug with water (at a constant pressure of approx. 1.25 MPa) included general monitoring and the monitoring and analysis of the outflows. Moreover, the monitoring process included the recording of the parameters of the structure of the plug itself and the surrounding rock mass every 10 minutes. The flow rate from the filters was measured both electronically and manually. Samples were taken from the outflows for basic chemical analysis.

The monitoring results indicated the gradual development of the saturation of the sealing part of the experiment with a simultaneous gradual increase in the swelling pressure; the outflows from the experiment decreased until stabilisation was attained. The progress of the experiment to date suggests that the plug is fulfilling its intended function. The concrete component acts to retard the flow and prevents the erosion of the bentonite. As bentonite saturation progresses, the bentonite core takes over the main sealing function; this process is long-term.

Research support for the project design of the Czech deep geological repository for disposal concept safety assessment purposes

Duration: 2023-2024

Recipient: Consortium of firms

Subcontractors: SATRA, s r.o., Mott MacDonald CZ, s.r.o., ÚJV Řež, a.s., AFRY CZ s.r.o., CTU, Prague

The project follows on from a previous project conducted between 2016 and 2020 entitled “Research support for deep disposal design solutions”. The aim is to reduce the degree of uncertainty and to specify the requirements for the subsequent stage of the DGR site selection process and the safety assessment of the disposal concept.

The project tasks are as follows:

to provide support related to strategic-planning project work for the development of the DGR

to provide project support in the preparation of the technical design of the DGR surface area and its connection to the wider surroundings at the DGR candidate sites and the preparation of environmental impact assessments

to provide support in terms of the planning of the operation of the nuclear facility, waste handling and technical disposal design solutions, the clarification of uncertainties in previous projects and the synthesis of the results for the assessment of the disposal concept and the development of mathematical models to support the dimensioning of the DGR and its components – thermal and geotechnical

Dismantling of the Mock-Up Josef in-situ experiment

Duration: 2022-2024

Recipient: Faculty of Civil Engineering, CTU

Co-recipients: Faculty of Nuclear and Physical Engineering, CTU in Prague, ÚJV Řež a.s., TU Liberec and the Faculty of Sciences, Charles University, Prague

Mock-Up Josef was the first in-situ physical model in the Czech Republic to be constructed for the simulation of the vertical disposal of a container with spent nuclear fuel (SNF). It was installed in the Josef gallery in 2011. The aim of the project was to determine the behaviour and changes in the properties of a bentonite barrier subjected to long-term exposure to heat and groundwater saturation. This originally five-year project was completed in October 2022 and was followed by a project to dismantle the experiment.

The dismantling project was scheduled to last for two years and was divided into five stages. The first two stages were launched in 2022: an implementation project was prepared for the dismantling of the experiment (stage 1) and the experiment was successfully dismantled (stage 2).

The third stage (2023) comprised the analysis of the collected samples and the fourth stage will commence in 2024 concerning the preparation of mathematical models. The project will be concluded with the preparation of a final report in August 2024, which will assess the stability of the bentonite with regard to the conditions in which the experiment was conducted over a total of more than 10 years. Dry density

Research support for the safety assessment of the DGR technical design – FEP analysis

Duration: commencement 2021

Recipient: AFRY CZ s.r.o.

Subcontractors: ÚJV Řež a.s., Faculties of Civil Engineering and Nuclear Sciences and Physical Engineering, CTU, PROGEO s.r.o., Czech Geological Survey

The project is aimed at enhancing knowledge for the evaluation of DGR long-term safety. This knowledge will be used in the preparation of materials for the evaluation of the safety of potential technical designs for the DGR and the DGR site selection process.

The project is using domestic and foreign resources to identify and analyse potential FEPs (Features, Events, Processes). FEPs were analysed in 2021-2022 based on which scenarios were defined in 2023 for the development of that part of the deep geological repository designated for the disposal of waste packages with spent nuclear fuel.

involved in the research of bentonite barriers and the structural parts of the DGR and their interfaces with the rock mass and the waste disposal packages.

Backfilling and other engineered components of the DGR

Duration: 2021 - 2026

Recipient: Faculty of Civil Engineering CTU

Subcontractors: AFRY CZ s.r.o.; Technical University of Liberec; ÚJV Řež, a.s.; SATRA, spol. s.r.o.; SG Geotechnika a.s.

The project concerns DGR engineered barrier components, i.e. the filling of the disposal wells/chambers and corridors and other DGR components including sealing plugs and the backfilling of other areas of the DGR. The project is divided into 15 subtasks.

Engineered barriers, which introduce artificial materials to the DGR, are intended to ensure the long-term safety of the repository. They include the waste disposal package (WDP) and the backfilling of the disposal wells (for spent nuclear fuel), chambers (for the disposal of other radioactive waste) and corridors.

The disposal well backfilling (buffer) prevents the inflow of water to the containers, guarantees the removal of heat, retards the possible migration of radionuclides and dampens the effect of microbial activity. The backfilling of the corridors prevents the formation of preferential pathways for radionuclides.

The project is focusing on the analysis of the key processes that influence the behaviour of backfill materials, the characterisation of the properties of engineered barriers based on clays and the assessment of the degree of their transformation. The output of the project will comprise a “Proposal for the Czech conceptual design of the buffer, backfill, plugs and chamber backfill for non-SNF RAW, other filling materials and structural elements (materials + technical solution)”.

Scheme of the backfilling of a disposal site – conventional excavation

Loading of a material suspension into the oven

European Joint Programme on Radioactive Waste Management

Duration: 2019 - 2024

Recipient: 51 institutions from 21 European countries

Cooperation between 51 organisations from 21 European countries commenced in June 2019 in connection with the EURAD – European Joint Programme on Radioactive Waste Management – platform. The main objectives of the EURAD project are to support research and development concerning the safe management of various types of radioactive waste in the participating countries, to develop the knowledge base for the safe construction of deep geological repositories, and to strengthen knowledge management and the transfer thereof between organisations and countries.

The research covers several areas, for four of which the CEG is acting as a “third party” for SÚRAO (the Czech WMO), i.e. the following work packages: CORI (Cement-Organics-Radionuclide Interactions), GAS (Mechanics Understanding of Gas Transport in Clay Materials), HITEC (Influence of Temperature on Clay-based Material Behaviour) and MAGIC (Chemo-Mechanical AGIng of Cementitious materials). The CEG is also acting as the coordinator for other CTU departments involved in the EURAD project and assists in the coordination of the HITEC work package.

the CEG participated in the preparation of concrete samples from the Richard repository and their subsequent analysis. Moreover, the CEG is studying the influence of external conditions (temperature, radiation) on the behaviour of cement pastes containing organic plasticisers.

Research on gas flow in a bentonite barrier, which is simulated by the long-term and cyclical testing of Ca-Mg bentonite samples, is underway as part of the GAS working group.

Concerning the HITEC WP, the CEG is investigating the influence of long-term thermal loading on the geotechnical parameters of bentonite. The CEG is measuring these parameters during thermal loading (130°C) and is conducting a small-scale thermo-hydraulic experiment (chamber diameter 30 cm, height 30 cm) that will lead to the acquisition of data for mathematical modelling purposes.

MAGIC concerns the development of the mechanical properties of cement materials exposed to chemical influences from the DGR environment. The mechanical behaviour of a low pH cement material is being studied at the micro and macro scales. The test programme includes artificial ageing taking into account chemical and microbial effects and real underground conditions. The CEG is focusing on macro-scale mechanical behaviour. The CEG is also participating in one of the three WPs focusing on Knowledge Management, specialising in “Training and Mobility”.

Engineered Barrier 200C

Duration: 2018 - 2025

Recipient: Faculty of Civil Engineering CTU

Subcontractors: Faculty of Natural Sciences, Charles University, Czech Geological Survey, Teramed, Application guarantor: SÚRAO

Deep geological repositories (DGR) are considered to be the only safe alternative for the disposal of spent nuclear fuel. The DGR safety concept is based on a multi-barrier system that acts to prevent the spread of contaminants into the environment.

The project concerns the research of the behaviour of the engineered barrier at elevated temperatures, i.e. 150°C – 200°C. The operation of the physical model will allow for the determination of more accurate input data for the safety analysis.

Following the successful completion of the construction of the “High Temperature Disposal Site Model” in October 2019, work on the other project outputs began. The “Operation of an advanced barrier at high temperatures” is ongoing and data from the sensors located in the model is being continuously recorded, stored and processed.

The operation of the physical model of the barrier and work on other outputs of the project continued in 2022. The fourth set of samples of the material were taken from the experiment and work started on their characterisation. At the end of 2023, preparatory work commenced for the dismantling of the experiment.

The results of the project to date were presented at the Underground Construction Prague 2023 conference.

View of a sample box with the sample after extraction from the in situ experiment

Filling of a space in the in situ experiment after sampling

Interaction physical models at the Bukov URF

Duration: 2017 – 2022

Recipient: Faculty of Civil Engineering CTU

Subcontractors: ÚJV Řež, a.s., Czech Geological Survey

The aim of the project is, based on the conducting of interaction experiments (IE) in a real rock environment, to compare several types of materials and their reactions in the deep geological repository (DGR) environment. The subsequent assessment of the project will recommend or exclude the use of specific materials and their combinations in the future DGR

A total of 10 models (PhyM) have been in place since March 2019; all of them were artificially saturated with water. The heater temperature of five of the PhyMs is approx. 100°C and the other five 200°C. The monitored variables (temperature, pore pressure, total stress and relative humidity) are recorded on the data network on the web interface.

Groundwater samples are taken regularly for chemical and microbiological analysis purposes. The samples have not, to date, indicated any significant changes in the monitored parameters. The analysis of the microbial population in the groundwater and bentonite samples, based on DNA extraction and analysis, revealed that aerobic organisms predominate.

Removing the heater for servicing Control system relay (after servicing)

Participation in other projects

Geopolymer samples are being tested in the Josef underground laboratory as part of the Advanced building materials for the nuclear industry project (TK03020188). A total of 75 geopolymer samples with dimensions of 50 x 50 x 50 mm have been emplaced in a niche in the underground laboratory. The exposure of the samples is ensured via the free flow of groundwater. The collection of samples and the study of the impacts of the length of sample loading on the properties of the geopolymers are ongoing.

The CEG is also involved in several projects underway at the Bukov underground research facility (URF).

Project 1: ÚJV Řež is the main research partner in the Pilot Corrosion Experiment at the Bukov URF. The project concerns the testing of the corrosion behaviour of samples of materials intended for the production of radioactive waste disposal packages. Testing is underway in the in situ environment of the Bukov URF.

Project 2: The CEG is a subcontractor for the Czech Geological Survey in the Geological and geotechnical characterisation of the rock environment – Bukov URF II project. The CEG’s contribution concerns the testing of equipment and procedures for the hydraulic testing of the excavation damaged/disturbed zone. Pilot tests were conducted in 2023 in the Josef gallery, which was followed by testing in the Bukov URF.