Recent studies on various solid-state electrolytes showed that while improvements to the ionic conductivity are progressing swiftly, the understanding of the fundamental conduction mechanism is still lagging behind. We attempt to improve this understanding by providing a more complete overview of how different static (structural) and dynamic (lattice-ion interaction) properties relate to the ion diffusion mechanism, by investigating the differences between the Na3PnS4 isostructural compounds (Pn = P, As, Sb). The static bottleneck descriptors previously used in literature, based on the S-atoms coordinating the ion migration pathway, are found to not predict the ionic conductivities accurately. On the dynamic influences, we find that based on the melting points, Born Effective Charges, vibrational frequencies and dissociation energies, it seems that of the Pn-S bonds the P-S bonds are significantly stiffer than the As-S and Sb-S bonds and that based on the differences in electronegativities, Bader Charges and Electron Localization Functions the bonds are least polar for As-S, followed by P-S and Sb-S. The changes in the bond polarity were found to correlate more closely with the observed differences in ionic conductivity than the bond stiffness, and closer inspection of the differences in the bond polarity suggest that the Pn substitution in the PnS4 anions (following the order As  P  Sb) causes a decrease in the Na-S bonding strength through electron transfer from the Na-ions to the S-ions. We quantified the conduction process further by determining the activation barrier with the Nudged Elastic Band method, with which we find that both the ionic conductivities and thus polarity correlate well with the activation barriers. Finally, we find that while the statis bottleneck descriptors are not great predictors of the overall conductivity, they do correlate with the activation volume, indicating an important role for these structural descriptors in studying pressure effects on conductivity.

As protons have a localized depth-dose distribution, proton therapy nowadays is a form of radiotherapy that is being implemented for part of the cancer patients. Compared to photon therapy it allows more precise targeting of tumours and sparing of surrounding healthy tissue. Besides patient treatment, research on proton therapy topics is being done to gain more knowledge on and keep improving the technique. Since the 1950s almost 100 proton therapy facilities are operating clinically worldwide. One of those facilities is HollandPTC, a proton therapy center located in Delft, The Netherlands. The ProBeam Varian cyclotron serves two treatment gantries, an eye treatment room, and a research experimental room. The experimental room is dedicated to research topics in the proton therapy field and is equipped with a fixed horizontal beam line that can be used for physics experiments and also for radiobiological experiments. In order to perform those types of research the beam needs to be fully characterized in terms of dose, shape, size and energy, this is the purpose of this work. The second goal was to commence with a setup for creating homogeneous fields by means of passive scattering and determine the optimal distances required between the elements of the setup. The single pencil beam characterization has been done by performing a large variety of experiments, making use of setups with different types of detectors. The experiments include beam spot, beam envelope, beam current, and depth-dose distribution measurements, and have been performed for nominal beam energies between 70 and 240MeV. For the passively scattered field a dual ring setup has been implemented. Spread-out Bragg peaks have been created with a ridge filter. An energy of 150 MeV was used, as the scattering elements have been designed for this energy specifically. The single pencil beam characterization resulted in beam spot sizes at the isocenter varying from 3.54 mm for 240 MeV, up to 5.47 mm for 70 MeV, with an asymmetry of 1.7% at most. The beam envelope measurements showed that the beam spot size just after the exit window is 2-3 mm and diverges up to 12 mm at 2 m from the exit window. The beam current measurements gave the transmission efficiency of the system, ranging from 0.04% for a 70 MeV beam up to 5.6% for 240 MeV, increasing exponentially. The depth-dose measurements provided the difference between the nominal beam energy and the beam energy at the isocenter. The difference becomes smaller as the nominal beam energy increases and is 2.4% for a 70 MeV nominal beam and 0.3% for a 230 MeV nominal beam. With the dual ring setup fields of up to 25 cm in diameter have been formed with a uniformity of at least 97%. The ridge filter created a spread-out Bragg peak of 2.8 cm with a uniformity of 98% and also gave good results for other beam energies (100-200MeV). It can be concluded that the goals of the project have been reached as the beam has been characterized in terms of shape, current, and energy. Also some preliminary work for the passive field has been accomplished. The work on the dual ring setup can be further expanded by placing the ridge filter and a collimator in the setup, after which the field can be characterized in terms of dose. The results obtained from the single pencil beam characterization allowed for the first physics experiments to start at the experimental room of HollandPTC during the last year.

In this study, non-destructive methods are applied to quantify the influence of concrete degradation by geologic conditions on the ability to retain nuclear waste deep underground in The Netherlands. Nuclear reactors play an important role in all four scenarios of the recent report of the IPCC to reach the CO2 reduction goals. Safety related criticism against nuclear energy technology are less relevant for Generation IV nuclear power plants, of which several are scheduled to be constructed in Europe within the next few years. This is partially due to the inherent safety features of Gen IV power plant designs, where disasters experienced before (e.g., Chernobyl, Fukushima) are technically impossible. Concrete samples provided by COVRA are degraded by immersion in a solution that contains chlorides and sulphates in concentration levels that are similar to geologic conditions. The influence of concrete degradation on the internal structure of concrete has been investigated using X-ray and Neutron radiography. Pore size distributions, pore geometry and sorptivity are presented. In order to validate the results, standardized tests are performed and the results are compared.