Experimental and Computational Methods

Here you find a list of techniques available at the Institute of Resource Ecology with short descriptions of their in house applications. Additional details as well as the respective contact persons can be found by following the links provided with each method.


SPECTROSCOPY

  • In situ vibrational spectroscopyEyecatcher-
    The molecular processes of dissolved metal ions at mineral-water interfaces are monitored in real time by in situ IR spectroscopy using the ATR technique. Metal complexes of biomolecules in aqueous solution can be characterized. Complementary vibrational spectroscopic information can be obtained from FT-Raman spectroscopy. Peak assignments are complemented by quantum chemical calculations (DFT, MP2).
  • Time-resolved laser-induced fluorescence spectroscopy (TRLFS)
    Luminescence spectroscopy is a key experimental technique for speciation studies of the actinides in solids, in solution, and at interfaces. Our institute applies seven tunable and fixed wavelength laser systems to study the coordination environment of the actinides Am, Cm, U(VI) and U(IV), as well as multiple lanthanides, especially Eu(III). Speciation is trace concentration sensitive, and can be performed down to ~10-9 M depending on the fluorescent probe, with detection limits approximately two orders of magnitude lower. For heterogeneous natural samples a setup for µTRLFS with spatial resolution ~10 µm is available.
  • Magnetic spectroscopy (NMR, EPR, SQUID)
    Two NMR spectrometers (Agilent DD2 600 MHz, Agilent MR 400 MHz) are available for studying the interaction of lanthanides and early actinides in solution and in solid state. An Agilent MR 400 MHz NMR spectrometer is installed in the controlled area to investigate samples that contain transuranic elements in solution. State-of-the-art multinuclear 1D- and 2D-NMR methods are applied to investigate complexes of the actinides with biologically and environmentally relevant complexing agents.
    In addition, a Bruker ELEXSYS E500-10/12 EPR spectrometer is installed in the controlled area labs and available for use with actinides including transuranic elements. The magnetic methods are complemented by a QuantumDesign MPMS3 SQUID magnetometer also within the controlled area laboratories.
  • UV-Vis-NIR absorption spectroscopy
    Absorption spectra of aqueous samples can be recorded in the wavelength range from 190 – 3300 nm. Temperature control (0 °C – 70 °C) and measurements in inertgas/radionuclide glove boxes are optional. Long path flow cells (50 – 250 cm) are available for samples with low extinction. Time-dependent DFT (TD-DFT) calculations are used to reproduce experimental absorption spectra. 
  • Single-crystal X-ray diffraction (SC-XRD)
    Our single-crystal X-ray diffractometer, D8 Venture from Bruker, is installed in a controlled area for radioactive materials. The diffractometer is equipped with dual micro-focus X-ray tubes for Mo or Cu Kα radiation and a high-end Charge-Integrating Pixel Array (CIPA) detector, PHOTON II. This instrument is one of the few single-crystal X-ray diffractometers in the world, which enables SC-XRD measurements on highly radioactive actinide compounds with proper precautions for radiation safety.

DATABASES, MODELLING, AND MOLECULAR SIMULATIONS

  • THEREDA offers evaluated thermodynamic data for all compounds of dose relevant elements according to the present state of research.
  • RES³T is a digitized version of a thermodynamic sorption database as required for the parameterization of Surface Complexation Models (SCM).
  • Molecular simulations
    Various molecular modeling methods are used to predict the molecular structures of various actinide complexes and its spectroscopic properties..

SYNCHROTRON BASED TECHNIQUES

The Institute of Resource Ecology operates the Rossendorf Beamline (ROBL) at sector 20 of the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. In two hutches various spectroscopic and diffraction techniques are available:

  • X-ray absorption spectroscopy in a dedicated hutch equipped as a controlled area for radioactive samples with activities up to 187 MBq.
  • X-ray emission spectroscopy: a Johann-type spectrometer is currently under construction for high-resolution X-ray emission studies.
  • Surface X-ray diffraction: a diffraction setup consisting of a Huber six-circle diffractometer, a PILATUS 100K diode array area detector, and the corresponding beamline components is available for e.g. Crystal Truncation Rod (CTR) and Resonant Anomalous X-ray Reflectivity (RAXR) experiments.
  • X-ray diffraction: the diffractometer will also be suitable for Synchrotron Powder X-ray Diffraction, and equipped with the necessary detectors and components.

BIOLOGICAL TECHNIQUES


MICROSCOPY

  • Light microscopy

  • Chemical microscopy
  • Atomic force microscopy

    Visualization of biogenic and geogenic surfaces, surface modifications and biomolecules in the range of micro- to nanometers to investigate the interaction of microorganisms, mineral phases and biomolecules with metals by using a high resolution AFM and a coolable/heatable liquid cell.


REACTIVE TRANSPORT AND TOMOGRAPHY

  • We develop conservative and reactive radionuclide tracers using our cyclotron laboratory.

  • We have adopted positron emission tomography (PET) for the purpose of flow field tomography in opaque materials, particularly geomaterials.

  • We analyze the heterogeneity of crystal surface reactivity by various microscopic methods, such as vertical scanning interferometry, in combination with µ-focus X-ray CT, and use these data to calculate reaction rate maps.

  • We use and develop numerical methods for the analysis of crystal surface reactivity and for transport analysis at the pore scale and above.


COMPUTATIONAL CODES FOR REACTOR SAFETY CALCULATIONS

  • 3D reactor dynamics core simulator DYN3D developed by HZDRDYN3D Logo
  • Advanced thermal hydraulic system codes ATHLET and ATHLET-CD (developed by GRS)
    • Plant dynamics, accident and severe accident analysis
  • Integral code ASTEC (joint development by IRSN and GRS)
    • Accident and severe accident analysis
  • Monte Carlo code SERPENT2 developed by VTT Finland
    • Reference calculations for DYN3D verification
    • Cross section generation for the DYN3D code
  • Lattice code HELIOS2 developed by Studsvik-Scandpower
    • Cross section generation for the DYN3D code
  • Monte Carlo code TRAMO developed by HZDR
    • Fluence calculations of reactor pressure vessels
  • Monte Carlo code MCNP6
    • Fluence calculations of reactor pressure vessels

NANO-/MICROSTRUCTURE CHARACTERIZATION OF NUCLEAR MATERIALS

  • Analytical (scanning-) transmission electron microscopy ((S)TEM)
    (Scanning) transmission electron microscopy allows irradiation-induced defects such as dislocation loops to be observed at nm-resolution. Access to the depth-dependent distribution of defects produced by ion irradiation is gained using cross-sectional specimens prepared by the focused ion beam technique. The chemical composition of nm-sized precipitates is analyzed by means of the integrated energy dispersive X-ray spectroscopy.
  • Small-angle neutron scattering (SANS)
    Small-angle neutron scattering is diffuse elastic scattering at small scattering angles on non-periodic structures with sizes in the range of 0.5 nm < R < 100 nm making it a suitable tool for examining irradiation-induced precipitates and voids. From the measured angular dependence of the scattering intensity, conclusions can be drawn about the shape and size distribution of these objects. SANS provides statistically reliable and macroscopically representative measures of their number density and volume fraction.
  • Depth-sensing nanoindentation in combination with atomic force microscopy (AFM)
    While neutrons penetrate deeply into matter, energetic ions give rise to damage only in a µm-thin layer next to the surface. Nanoindentation is a suitable tool to probe the mechanical behaviour of thin layers. It provides a link between irradiation-induced nanofeatures (dislocation loops, voids, precipitates) and mechanical property changes.

  • Analytical Scanning electron microscopy (SEM, EDS, EBSD)
    Scanning electron microscopy combined with energy dispersive x-ray spectroscopy and back-scatter electron diffraction is a versatile tool in materials characterization. In nuclear materials research it contributes to the multi-scale characterization of the complex, hierarchical microstructures of irradiated materials, provides insight on fracture mechanisms (fractography) and – combined with the focused ion-beam technique (FIB) - allows the site/orientation-selective extraction of cross-section samples for transmission electron microscopy.

RADIOCHEMISTRY AND SPECTROMETRY

  • Radioanalytical methods
    α-spectrometry: Grid ionization chamber (GIK 800S, MAB) allows the analysis of thin layers up to ~300 cm² (limit of detection ~10−2 Bq).
    Semiconductor detector (PIPS: PH 450-21-100AM, Canberra) allows the analysis of thin layers up to ~4.5 cm² (limit of detection ~10−3 Bq).
    β-spectrometry: Liquid scintillation counting (LSC) with α/β discrimination (1400 Wallac Win Spectral, Tri-Carb 3100 TR, Perkin-Elmer).
    γ-spectrometry: High Purity Germanium Detection (Gamma-X HPGe, Coaxial Photon Detector, Ortec).
  • Colloid characterization techniques
    Light scattering: Dynamic and static light scattering (CGS-3 (ALV) and Zetasizer Nano ZS (Malvern Instruments) allows determination of size distributions of colloidal nanoparticles and molecular weights of macromolecules.
    Zeta-Potential: The zeta potentials of nanoparticles in dependence on pH can be determined by laser Doppler velocimetry using a Zetasizer Nano ZS (Malvern).
  • Mass spectrometry
    Inductively coupled plasma-mass (ICP-MS) spectrometry is highly sensitive for the quantification of elements in solid and liquid samples.

CALORIMETRY

  • Calorimetric methods are used to determine the thermodynamic parameters of protein stability and metal-ligand interactions using Differential Scanning Calorimetry and Isothermal Titration Calorimetry, respectively. The impact of heavy metals and radionuclides on the physiology of living organisms is monitored by Microcalorimetry.
  • Thermogravimetry / Differential Scanning Calorimetry (TG/DSC): Investigation of solid phase transformation, crystallization, melting, removal of water etc. in dependence of temperature (maximum 1600 °C) under air or inertgas atmosphere using a STA 449 F5 Jupiter (Netzsch).

MACROSCOPIC TECHNIQUES

  • Batch sorption experiments
    Sorption properties of different minerals towards inorganic and organic pollutants depending on various factors (e.g. pH, ionic strength, redox potential, temperature, presence of organic matter, microbes or competing species) are determined by batch experiments and thermodynamic parameters (Kd, ΔRH, ΔRS) are derived.
  • Lysimeter experiments
  • Determination of transport parameters (De, Kd, porosity)
    Small-scale stainless steel diffusion cells are used for investigation of radionuclide migration through minerals or rock materials.