HGF Infrastructure Project HOVER
The HGF centers FZJ, HZDR and KIT cooperating in the NUSAFE consortium are implementing the laboratory infrastructure "HOVER" (Helmholtz Research and Technology Platform for the Decommissioning of Nuclear Facilities and for the Management of Radioactive Waste) as a decentralized research infrastructure. HOVER is dedicated to support advanced scientific investigations and technical developments in the context of the German phase out of nuclear energy. To this end, HOVER provides state-of-the-art instrumentation to investigate radionuclides including α-emitting actinides and to study those processes which determine their behavior in interim storage facilities and deep geological repositories. As of today, in Germany such laboratories are not any more available at research facilities outside the Helmholtz Association. Moreover, HOVER is offering unique infrastructures for the development and demonstration of innovative decommissioning technologies. Thus, research performed within the HOVER platform covers scientific challenges and technical developments dealing with the entire chain of decommissioning, nuclear waste conditioning and final disposal.
Accelerator mass spectrometry (AMS)
A Multi‐Isotope Low‐Energy AMS (MILEA) System has been acquired from the company Ionplus AG (CH). MILEA (Fig. 1) features a 300 kV tandem accelerator and a compact setup that is optimized for analysis of the ultra-trace levels of the rare, long-lived radionuclides 10Be, 14C, 26Al, 41Ca, 129I and actinide nuclides.
A new building (B703, Fig. 2) adjoining the main buildings of KIT-INE is going to be built in order to host MILEA and be dedicated to AMS analysis, as well as sample preparation in a cleanroom laboratory with ISO 4 class. Sample handling and chemical treatment in such a cleanroom laboratory will allow for a significant decrease of the ubiquitous background from the global fallout of radionuclides and, in this way, for a further increase in the analytical sensitivity.
Construction work for the new AMS laboratory sees his start in the first quarter of 2025, while the installation and commissioning of MILEA is expected to be completed by mid-2026.
The analytical capability of determining rare, long-lived radionuclides at and below the fg levels in a variety of environmental samples allows addressing scientific question on radionuclide behavior that cannot be tackled with the more commonly used mass spectrometric and radiometric techniques. The extreme sensitivity of AMS provides access to processes in geochemical systems that occurred over a period of time of decades. This was demonstrated in the in-situ radionuclide tracer tests at the Grimsel Test Site.
With the new AMS laboratory at KIT-INE we will continue and further implement studies on the safety of nuclear waste disposal, determination of the status “quo ante” the decommissioning of nuclear facilities, as well as environmental monitoring and research on the geochemical behavior of relevant radionuclides.
Contact:
Dr. Francesca Quinto +49 721 608 22233
FIB-SEM
Overview
The analytical capabilities provided by INE’s surface analysis group have been expanded within the Helmholtz-funded technology platform HOVER for research on decommissioning of nuclear facilities and for the management of radioactive waste by a focused ion beam scanning electron microscope – Zeiss FIB-SEM, model Crossbeam 350 KMAT, with integrated fs-laser ablation module.
FIB-SEM operation modes:
- FIB-SEM operation
- Femtosecond-laser milling and polishing
- Energy dispersive X-ray Spectrometry (EDS)
- Electron backscatter diffraction (EBSD)
- TEM lamellae preparation
- Gas injection systems (GIS) for C or Pt deposition and contacting
- Focused ion beam (FIB) milling and polishing
- 2D- & 3D- topography & compositional studies
- Low pressure (N2) operation
Different imaging modes:
- Secondary electrons (SE) for imaging of surface topography
- Backscattered electrons (BSE) for compositional contrast imaging
- STEM detector for thin samples and particles
- EBSD detector for spatially resolved crystal structure analysis
Large Area Mapping (LAM) by SEM-EDX is an automatic acquisition of data from a large area by mapping multiple fields and stitching them together. Secondary and backscattered electron images, and X-ray signals are collected simultaneously.
Fig.3: EDS LAM major and minor phases: Opalinus sandy facies, Mont Terri. Sample diameter Ø = 25.4 mm, for total LAM 368 EDS fields are merged together with number of points per LAM being 256*192 pixels, Σ 18 million spectra.
Fig.4: Monte Carlo simulation of e-beam interaction with secondary phase and CuNi coupon at acceleration voltage of 15kV (A) done using CASINO v 2.48 software (PE-primary electrons, BSE- backscattered electrons and SE – secondary electrons). SEM image of secondary phase (B), EDS quantitative analysis (C) and EBSD Indexing (D) confirming formation of Cu2O as a secondary phase formed on the Cu-Ni alloy in contact with MX-80 bentonite slurry for 6 months.
Contact:
Dr. Natalia Müller +49 721 608 24602
Micro-computed tomography ( µ-CT)
A Zeiss Xradia 620 Versa X-ray microscope (µ-CT) for microtomographic measurements was put into operation at INE to investigate the bulk morphology of solid samples. The combination of FIB-SEM and X-ray microscopy enables, in principle, cross-scale investigations of materials from the decimeter to the nanometer range. As part of an intensive training phase, samples from various research areas at INE were characterized - for example, to map the 3D morphology of core samples from the host rocks of underground laboratories (as part of field studies on radionuclide migration) or from a sandstone formation that is being analyzed in connection with possible geothermal energy storage capacities on KIT Campus North. A custom-built in-situ diffusion cell for tomography experiments at elevated temperatures and pressures (e.g., to investigate reactive transport processes) is currently being implemented for the Xradia μ-CT instrument.
Contact:
Dr. Tim Prüßmann +49 721 608 22135
Surface analysis by atomic force microscopy (AFM)
Atomic Force Microscopy (AFM) allows to measure structures on solid surfaces. In-situ measurements in solution allow monitoring of changes during chemical reactions like crystal growth and dissolution or corrosion. At INE, a Cypher VRS-1250 AFM from Oxford Instruments with various extras like an electro-chemistry cell and the force mapping option is available (Fig. 1). Various measurement modes and scan rates up to video-rate-scanning may be realized. Figure 2 depicts the available range of scales from atomic resolution images of a calcite single crystal surface to relatively large-scale roughness measurements on a polished steel surface.
Contact:
Dr. Frank Heberling +49 721 608 24782
BIM D²-Lab
Digitalisation offers many advantages, including when dismantling nuclear facilities. In order to be able to adequately cover this topic in the dismantling of nuclear facilities, a digitalisation lab called BIM D² (Building Information Modeling Decommissioning & Deconstruction) has been set up at the Institute for Technology and Management in Construction (TMB) in the Department of Dismantling Conventional and Nuclear Buildings (https://www.tmb.kit.edu/english/941.php). For this purpose, premises are currently being upgraded on Campus East. As there were considerable delays during construction, an interim facility has been created at the TMB. The BIM D2 Lab on Campus East will be completed and occupied in the course of 2025.
Contact:
Madeleine Bachmann, M.Sc. +49 721 608 41577