Shaping change: this is what drives us at Forschungszentrum Jülich. As a member of the Helmholtz Association with some 7,600 employees, we conduct interdisciplinary research into a digitalized society, a climate-friendly energy system, and a sustainable economy. We focus on the natural, life, and engineering sciences in the fields of information, energy, and bioeconomy. We combine this with expertise in high-performance computing and artificial intelligence using unique scientific infrastructures.

We invite early-career researchers to apply for a PhD position within the joint research project “TRANSFER - Training and Research Academy for Nuclear Safety and Future Expertise on Geological Repository Systems”. As part of a structured doctoral program, you will conduct research on cutting-edge topics related to the disposal of high-level radioactive waste. TRANSFER is jointly funded by the German Federal Ministry for Research, Technology and Space (BMFTR) and the Federal Company for Radioactive Waste Disposal (BGE) and is coordinated by the GFZ German Research Centre for Geosciences.

Join our team Carbonate minerals are present in many claystone formations and can contribute to the retention of radionuclides through co-precipitation, surface reactions or the formation of solid solutions. The aim of this PhD project is to gain a comprehensive understanding of the retention of the radionuclides 226Ra and 90Sr in carbonate-bearing claystones through a combination of experiments and simulations, and to elucidate the competition between sorption and co-precipitation processes, as well as the reversibility of these processes. Furthermore, the effects of heterogeneities in the mineral composition and distribution on radionuclide migration in clay rocks will be evaluated. The findings will contribute to the improvement of process models for the cross-scale description and simulation of radionuclide migration in the near- and far-field of a geological repository for high-level radioactive waste.
Your main responsibilities within the project will include:

Conducting sorption/desorption experiments to determine the retention of 226Ra and 90Sr in carbonate-bearing claystones and its reversibility
Conducting recrystallisation experiments to investigate the structural uptake of 226Ra into carbonate minerals
Analysing selected samples from sorption and recrystallisation experiments using advanced analytical methods such as Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and synchrotron-based methods (µ-XRF and µ-XRD)
Application of geochemical-thermodynamic modelling to interpret the experiments
Collaboration with modellers (reactive transport) to evaluate the migration behaviour of 226Ra and 90Sr in heterogeneous claystone formations across various spatial and temporal scales
Presentation of results at scientific conferences and in peer-reviewed publications

Master’s degree, diploma or equivalent in chemistry, radiogeochemistry, environmental chemistry, geochemistry, chemical engineering, mineralogy or related field
Experience of working in wet chemical laboratories
Experience in geochemical or thermodynamic modelling is desirable
Ability to work collaboratively within a multidisciplinary and international team
Very good command of written and spoken English with extensive vocabulary is required (at least B2 level according to the CEFR), ideally supported by a certificate confirming the language level
We work on the very latest issues that impact our society and are offering you the chance to actively help in shaping the change! We offer ideal conditions for you to complete your doctoral degree:

A structured training programme: Within the TRANSFER graduate school on geological disposal, comprising seminars, summer and winter schools, participation in conferences, and the opportunity for research stays at partner institutions, aiming at a comprehensive...