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Coupled hydro-mechanical effects in Opalinus Clay (OPA) are of significant interest regarding the stability and integrity of a potential storage facility for high-level radioactive waste (HLW). In the Mont Terri Rock Laboratory, the CD-A twin niches differ only in their ventilation and enable the investigation of near field effects like desaturation and development of the excavation disturbed zone (EDZ). Amongst others, the evolution of water content and deformation are observed and provide a comprehensive data set as basis for a pragmatic approach to capture effects in the EDZ in safety assessment. The measuring campaign includes electric resistivity tomography (ERT), providing daily measurements of the electric resistivity distribution up to a few meters into the rock formation, as well as the nuclear magnetic resonance method (NMR) aiming on the evolution of water content near the surface of the niches. Due to the corresponding effort in handling the relatively new single-sided application, the NMR measurements are only conducted once per season. Nevertheless, the combined interpretation of NMR and ERT provides valuable data of water content and hydraulic conductivity evolution enabling a meaningful optimization of numerical modelling approaches. The interpretation of the water content evolution in combination with the geologic characterization demonstrates the high heterogeneity of the sandy facies of OPA, a significant impact of the ventilation, and a correlation of high resistivity regions with open fractures, indicating potential preferential flow paths that are relevant for transport processes. As a matter of fact, the results illustrate a need to discuss the set-up of numerical modelling, especially concerning the boundary conditions, the heterogeneities, and the parametrization and set-up of the EDZ. Further measuring focus on the displacements around the niches. While laser scans represent the convergence behavior near the surface, extensometers generate information about the displacements a few meters around the twin niches. Summarizing these data, the convergence behavior near the surface as well as a few meters around the twin niches depends significantly on the ventilation of the niches, indicating seasonal effects and differences in the long-term convergence behavior. Future work aims on an increased system understanding considering long-term effects due to climatic conditions, geotechnical boundary conditions, heterogeneities amongst others and their realistic representation in safety assessment.

A potential repository site for high-level radioactive waste should ensure the highest possible safety level over a period of one million years. In addition to design issues, demonstrating the integrity of the barrier is essential as it ensures the long-term containment of radioactive waste. Therefore, a multi-disciplinary approach is necessary for the characterization of the surrounding rock and for the understanding of the occurring physical processes. For site selection, however, the understanding of the respective system is essential as well: Do fault zones exist in the relevant area? Are these active and relevant for interpreting system behavior? What is the role of the existing heterogeneities of the claystone and how do these site-dependent conditions influence the physical effects? To answer these questions, the site-selection procedure requires underground exploration, which includes geophysical and geological investigations on milli- to decameter scales. Their results serve as the basis for numerical modelling. This combined, multi-disciplinary interpretation requires extensive knowledge of the various methods, their capabilities, limitations, and areas of application. In the cyclic deformation (CD-A) experiment in the Mont Terri rock laboratory, the hydraulic–mechanical effects due to excavation and the climatic conditions within the rock laboratory are investigated in two niches in the Opalinus Clay. The twin niches differ mainly with regard to the relative humidity inside them, but are also characterized by different boundary conditions such as existing fault zones, the technical construction of the neighboring gallery, etc. In order to gain insights into the relevance of the individual influences, comparative studies are being carried out on both niches. The presented results provide a first insight into the initial experimental years of the CD-A long-term experiment and illustrate the benefits of multi-disciplinary investigations in terms of system understanding and the scale dependency of physical effects. Amongst other effects, the assessment of the impact of heterogeneities on the deformation behavior and the evolution of pore water pressure is very complex and benefits from geological interpretation and measurements of for example deformation, water content, and pore pressure. The numerical modeling allows statements about the interaction of different processes and thus enables an interpretation of the overall system, taking into account the knowledge gained by the multi-disciplinary investigation.

For deep geological disposal of high-level radioactive waste (HLW) in granite, the temperature on the HLW canisters is commonly designed to be lower than 100 °C. This criterion dictates the dimension of the repository. Based on the concept of HLW disposal in vertical boreholes, thermal process in the near field (host rock and buffer) surrounding HLW canisters has been simulated by using different methods. The results are drawn as follows: (a) the initial heat power of HLW canisters is the most important and sensitive parameter for evolution of temperature field; (b) the thermal properties and variations of the host rock, the engineered buffer, and possible gaps between canister and buffer and host rock are the additional key factors governing the heat transformation; (c) the gaps width and the filling by water or air determine the temperature offsets between them.

The transit time distribution (TTD) of discharge collected from fractures in the Bedrichov Tunnel, Czech Republic, is investigated using lumped parameter models and multiple environmental tracers. We utilize time series of $$\delta ^{18}O$$ , $$\delta ^{2}$$ H and $$^3$$ H along with CFC measurements from individual fractures in the Bedrichov Tunnel of the Czech Republic to investigate the TTD, and the uncertainty in estimated mean travel time in several fracture networks of varying length and discharge. We compare several TTDs, including the dispersion distribution, the exponential distribution, and a developed TTD which includes the effects of matrix diffusion. The effect of seasonal recharge is explored by comparing several seasonal weighting functions to derive the historical recharge concentration. We identify best fit mean ages for each TTD by minimizing the error-weighted, multi-tracer $$\chi ^{2}$$ residual for each seasonal weighting function. We use this methodology to test the ability of each TTD and seasonal input function to fit the observed tracer concentrations, and the effect of choosing different TTD and seasonal recharge functions on the mean age estimation. We find that the estimated mean transit time is a function of both the assumed TTD and seasonal weighting function. Best fits as measured by the $$\chi ^2$$ value were achieved for the dispersion model using the seasonal input function developed here for two of the three modeled sites, while at the third site, equally good fits were achieved with the exponential model and the dispersion model and our seasonal input function. The average mean transit time for all TTDs and seasonal input functions converged to similar values at each location. The sensitivity of the estimated mean transit time to the seasonal weighting function was equal to that of the TTD. These results indicated that understanding seasonality of recharge is at least as important as the uncertainty in the flow path distribution in fracture networks and that unique identification of the TTD and mean transit time is difficult given the uncertainty in the recharge function. However, the mean transit time appears to be relatively robust to the structural model uncertainty. The results presented here should be applicable to other studies using environmental tracers to constrain flow and transport properties in fractured rock systems.

The paper is intended to define a benchmark problem related to groundwater flow and natural tracer transport using observations of discharge and isotopic tracers in fractured, crystalline rock. Three numerical simulators: Flow123d, OpenGeoSys, and PFLOTRAN are compared. The data utilized in the project were collected in a water-supply tunnel in granite of the Jizera Mountains, Bedřichov, Czech Republic. The problem configuration combines subdomains of different dimensions, 3D continuum for hard-rock blocks or matrix and 2D features for fractures or fault zones, together with realistic boundary conditions for tunnel-controlled drainage. Steady-state and transient flow and a pulse injection tracer transport problem are solved. The results confirm mostly consistent behavior of the codes. Both the codes Flow123d and OpenGeoSys with 3D–2D coupling implemented differ by several percent in most cases, which is appropriate to, e.g., effects of discrete unknown placing in the mesh. Some of the PFLOTRAN results differ more, which can be explained by effects of the dispersion tensor evaluation scheme and of the numerical diffusion. The phenomenon can get stronger with fracture/matrix coupling and with parameter magnitude contrasts. Although the study was not aimed on inverse solution, the models were fit to the measured data approximately, demonstrating the intended real-case relevance of the benchmark.

The present work discusses the numerical modelling of thermo-hydro-mechanical coupled processes for two in situ experiments on engineered barrier systems, which were performed at a real test site in the geological underground. Based on the phase related balance equations for mass, linear momentum and energy, a classical continuum approach for multiphysics analyses in porous media is presented. Within this context, the non-isothermal Richards' approximation is used for flow simulations in a partially saturated deformable solid skeleton. Regarding the constitutive modelling, basically relations typically discussed in literature for the applications under consideration are applied, and are calibrated on experimental data. Some specific problem-related modifications are presented. An incremental staggered finite element scheme is preferred to solve the coupled nonlinear initial-boundary value problem. Due to the process complexity of the combined simulation of both of the in situ experiments, a 3-D model is required. Additionally, the realisation of parallel algorithms in conjunction with high performance computing facilities essentially improves the efficiency of the numerical simulations. The presented models and algorithms are implemented into the scientific finite element code OpenGeoSys. Based on the analysis of the in situ experiments under consideration, the capabilities of OpenGeoSys to model application-oriented problems are shown.

Es wird uber Untersuchungen auf echten Vitamin A-Mangel an Hand der Adaptometrie berichtet. Unter 50 Gesunden wurden 3 leichte Falle, unter 50 Kranken 12 mittelschwere und 3 schwere Falle, unter 90 Schwangeren 11 mittelschwere und 4 schwere Falle, unter 9 Stillenden 3 leichte Falle gefunden. Durch laufende Kontrollen der mit „Vogan“-Tabletten behandelten Vpn. wurde erstmalig ein zahlenmasig erfastes, biologisch nachgewiesenes Defizit fur Vitamin A am Menschen aufgedeckt. Das Defizit bewegte sich in den Werten von 72000 bis uber 300000 intern. Einheiten A, entsprechend etwa 43 bis uber 200 mg (!)β-Carotin. Bezuglich der Ursache wird die Ernahrungsfrage diskutiert und auf den erheblichen Mehrbedarf von Schwangeren und Stillenden aufmerksam gemacht. Es wird nachgewiesen, das zwischen minimaler und optimaler A-Versorgung eine sehr breite Spanne liegt, die erstmalig zahlenmasig umrissen werden konnte.

Excitation- and emission spectra of Cl 2 in Neon-matrix, Argon-matrix and Ne-Ar mixtures were measured using synchrotron radiation as excitation source. In Neon, only the laser-emission of Cl 2 at about 4.7 eV was observed. In Argon-matrix as well as in mixtures of Ne and Ar, new emission bands appear, which could be attributed to Cl 2 -Ar complexes. By photolysing the sample, Cl-atoms have been produced, which were stable in the matrix. After photolysis, fluorescence of ArCl and Ar 2 Cl excimers could be observed. By varying the Ar amount in the mixtures, we were able to obtain information about the number of Ar atoms involved in the several complexes.