Luka Snoj
@ijs.si
Faculty of Mathematics and Physics, University of Ljubljana
Jozef Stefan Institute
Scopus Publications
Scopus Publications
Primož Lesjak, Aljaž Čufar, Domen Kotnik, Julijan Peric, Marco De Pietri, and Luka Snoj
Elsevier BV
Julijan Peric, Domen Kotnik, Domen Govekar, Luka Snoj, and Vladimir Radulović
Elsevier BV
Klemen Ambrožič, Hubert Carcreff, Vladimir Radulović, Damien Fourmentel, Christophe Destouches, Nicolas Thiollay, and Luka Snoj
Springer Science and Business Media LLC
Abstract Nuclear heating plays an important aspect in design and deployment of both fission and fusion reactors and experimental devices in terms of cooling requirements. Two experimental campaigns in the framework of a collaboration project between the French Atomic and Alternative Energy Commission (CEA) and Jožef Stefan Institute (JSI), Slovenia, have been performed at the JSI TRIGA reactor for the experimental assessment of nuclear heating in fission and fusion-relevant materials by the differential calorimetry technique, based on the CALMOS and CARMEN differential calorimeters, previously developed at CEA. The results of the first campaign performed at reactor powers between 100 and 250 kW have already been reported, highlighting some measurement difficulties. Therefore, the second campaign was performed at a lower reactor power of 30 kW to overcome these issues. Moreover, a computational analysis of the experiments was performed using the JSIR2S code package to calculate the nuclear heating levels. Both experiments and their reproduction by simulations are described in detail. We present a comparison of the previously reported measured nuclear heating values of the first campaign with the computational results, with consistent underestimation by simulations by 8–35%. We report the experimental and computational results for the second experimental campaign performed at a reactor power of 30 kW. The simulated heating values were in agreement with the measurements within the measured heating uncertainty, with simulated heating 2.7–11.3% lower than the experimental values.
Julijan Peric, Luka Snoj, and Vladimir Radulović
Elsevier BV
Julijan Peric, Domen Govekar, Sebastjan Rupnik, Luka Snoj, Rosaria Villari, Nicola Fonnesu, Stefano Loreti, Perry Beaumont, Slawomir Mianowski, Callum Grove,et al.
IOP Publishing
Abstract In water-cooled D–T fusion tokamaks such as the Joint European Torus (JET), neutron activation of flowing water produces short-lived radionuclides that generate a distributed high-energy gamma and neutron radiation source in the water cooling circuit. The energy and intensity of the source are crucial factors in the design of cooling and shielding systems in future water-cooled deuterium–tritium fusion tokamaks such as ITER. While several past experiments provide fusion-relevant experimental data on water activation, the JET water activation experiment carried out during the 2023 DD and DT campaigns is the first such experiment in a fusion tokamak environment. In the water activation experiment at JET, two types of scintillation detectors were used to measure gamma rays from activated water in the basement below JET Octant 4. The system successfully recorded and processed data from over 1500 JET pulses, including both DD and DT operations, providing a robust data set for analyzing N-16 activity in cooling water. This manuscript describes the preparation of the JET water activation experiment, the calibration of the detectors and the analysis of the experimental data.
Max Fratoni, Chris Perfetti, Eva Davidson, Brendan Kochunas, and Luka Snoj
Informa UK Limited
Tanja Goričanec, Benjamin Barbarič, Vladimir Radulović, Dušan Čalič, Luka Snoj, and Marjan Kromar
Elsevier BV
I. Švajger, N.C. Fleming, A.I. Hawari, B. Laramee, G. Noguere, L. Snoj, and A. Trkov
Elsevier BV
Julijan Peric, Domen Kotnik, Domen Govekar, Luka Snoj, and Vladimir Radulović
EDP Sciences
This paper presents the characterization of the KATANA water activation facility in the TRIGA research reactor at the Jožef Stefan Institute (JSI), operating the reactor in pulse mode and using neutron detection techniques. The facility plays a crucial role in the benchmarking and validation of computational models relevant to nuclear fusion applications, particularly in the context of ITER. A dual approach was used to determine the system volume of the KATANA loop: a direct volumetric method involving a physical measurement and a novel neutron-based method using the circulation of neutron-activated water. The latter uses a 3 He proportional counter to track the flow and decay of the short-lived 17 N nuclides that emit neutrons with energies in the MeV range. Experimental results from both methods provided consistent volume estimates and confirmed the reliability of the neutron-based dynamic characterization technique. These results support future efforts in the development and validation of neutron and activation models for fusion-related systems.
Ylenia Kogovšek Žiber, Benjamin Barbarič, Domen Kotnik, Julijan Peric, Luka Snoj, and Igor Lengar
EDP Sciences
The primary coolant in fusion reactors such as ITER is water. In recent years, research has increasingly focused on the irradiation and activation of water, which leads to the formation of ionizing radiation fields. To better understand these phenomena, the KATANA irradiation facility for water activation was commissioned in early 2024 at the Jožef Stefan Institute. Since its initial testing, several upgrades and developments have been implemented. In 2026, the inner irradiation head where the water is irradiated in the reactor, is planned to be removed and replaced with an ITER relevant head design that more accurately replicates ITER’s cooling components. Ahead of this replacement, a comprehensive neutron activation analysis of the current head, has been conducted to support the licensing process and ensure the safe removal. This paper presents the results of activation calculations for the inner head after long-term operation of KATANA, utilising the neutron irradiation field of the JSI TRIGA reactor. These preliminary calculations will aid in ensuring the safe maintenance of the KATANA facility and provide valuable insights for predicting the activation of its internal components.
Ioannis Tsitsimpelis, Andrew West, Kartikey Mathur, Anže Jazbec, Luka Snoj, Shengshu Liu, Andrew Kennedy, Francis R. Livens, Barry Lennox, C. James Taylor,et al.
EDP Sciences
An adaptive approach driven by Bayesian Optimization is described for applications where remote radiation measurements made with robots are constrained by stringent upper thresholds on the mass and power payload of the necessary instrumentation, as well as by the time window within which measurements must be made, ultimately affecting their quality and maximum area coverage. The algorithm presented in this paper is applied to a gimbal assembly the comprises a collimated cerium bromide detector to perform γ-localization. A Gaussian Process models the angular distribution of radiation, and measurement locations are dynamically selected via a composite acquisition function, which combines the Expected improvement and Uncertainty Confidence Bounds functions. Convergence is driven by monitoring the rate of change of predictions and associated mean uncertainty. This approach enables accurate characterization of radiation fields while requiring up to 85% fewer measurements than conventional raster-type scanning. Its performance is evaluated in simulation, using previously obtained datasets used as measurement look-up tables, and validated in turn with hardware implementation, real-time scans.
Eduardo Masiá, Francesca Cau, Aljaz Kolsek, Raúl Pampín, Marco Fabbri, Luka Snoj, Domen Kotnik, Rosaria Villari, and Alfredo Portone
Elsevier BV
R. Villari, X. Litaudon, J. Mailloux, M. Dentan, N. Fonnesu, Z. Ghani, L.W. Packer, F. Rimini, R. Vila, R. Afanasenko,et al.
Elsevier BV
Julijan Peric, Domen Kotnik, Luka Snoj, and Vladimir Radulović
Elsevier BV
Luka Snoj, Klemen Ambrožič, Loïc Barbot, Ljudmila Benedik, Arne Bratkič, Ivana Capan, Christelle Reynard-Carette, Vladimir Cindro, Dušan Čalič, Christophe Destouches,et al.
Elsevier BV
Domen Kotnik, Julijan Peric, Domen Govekar, Luka Snoj, and Igor Lengar
Elsevier BV
Domen Kotnik, Julijan Peric, Domen Govekar, Luka Snoj, and Igor Lengar
Elsevier BV
Jan Malec, Iztok Tiselj, Leon Cizelj, Anže Pungerčič, Tanja Goričanec, and Luka Snoj
Springer Science and Business Media LLC
AbstractThe TRIGA Mark II research reactor at the Jožef Stefan Institute in Slovenia achieved first criticality in 1966. Since then, the reactor has been playing an important role in developing nuclear technology. The reactor has been mainly used for research, education of university students, training of operators of the Krško nuclear power plant (start of operation in 1983) and other nuclear specialists, isotope production and beam applications. The reactor is experiencing a high level of activity today, engaging in a diverse range of experiments and studies across reactor physics, environmental research, radiation hardness testing as well training and education. The future of nuclear technology in Slovenia is focused on new NPPs, while the research community is looking forward to a possible new nuclear reactor. The basic initiatives are at a very preliminary stage: the primary choice is dual-core pool-type reactor, with a zero-power core and a separate MW-size core, cooled and moderated with light water. Such a dual-core configuration is designed to meet the varied requirements of the European Union member states. Another option would be hosting one or more micro-reactors with electrical and/or heating power producing capability that could offer stronger support toward demonstration of prototype small modular reactors in prototype future electrical grids.
Anže Pungerčič, Vicente Bécares, Daniel Cano-Ott, Roberta Cirillo, Tom Clarijs, Jacek Gajewski, Bor Kos, Renata Mikołajczak, Evžen Novák, Gabriel Pavel,et al.
Elsevier BV
Abida Zahirović, Špela Zupančič, Andraž Verdir, Sebastjan Nemec, Slavko Kralj, Luka Snoj, and Aleš Berlec
Frontiers Media SA
Introduction With growing evidence of clinical efficacy of probiotics in various diseases, safety concerns have arisen regarding the therapeutic use of live probiotic bacteria, especially in critically ill, immunocompromised, and pediatric populations. Serious probiotic-related adverse effects have been reported in these patients, including bloodstream infection and sepsis. This has led to an increased interest in developing postbiotics (non-viable bacterial products) that may exert beneficial effects on the host without the risks associated with administration of live microorganisms. The aim of this study was to explore postbiotic potential of recombinant Lactococcus lactis bacteria that have been engineered to display interleukin 6 (IL6)-targeting affibody (ZIL6) on their surface and are intended for treatment of inflammatory intestinal diseases. Methods Five different killing treatments were applied to kill bacteria (heat, ethanol, sonication, UV, and gamma irradiation) and their effect on bacterial viability, morphology and functionality was examined in vitro using a combination of different techniques, including microscopy, flow cytometry, immunoassays and cell-based reporter assay. Results The results showed that ZIL6 affibody displayed on L. lactis via non-covalent anchoring withstood the treatments applied to kill bacteria and remained functional after the loss of microbial viability. The degree of functionality was dependent on the type of treatment. Heat-killed cells retained 50% of the activity of live strain, while most of the activity was preserved after exposure of bacteria to ethanol, sonication, UV and gamma irradiation. The applied treatments varied in killing efficacy, whereby ethanol and heat rendered bacteria non-viable, UV and gamma irradiation yielded non-replicative cells, whereas sonication was ineffective in killing L. lactis . Among non-viable cells, ethanol-killed bacteria exhibited the greatest activity and showed high maximum binding capacity of 200 ng IL6 per mg dry cell weight, possessed strong nanomolar affinity for IL6, and inhibited up to 78% of IL6-induced STAT3 signaling. Conclusion The study demonstrates that functional non-viable bacterial cells can be derived from the recombinant L. lactis with therapeutic proteins displayed on their surface and provides a good foundations for further studies of their postbiotic potential in adjunctive therapy of inflammatory intestinal diseases.
Valentin Valero, Laurent Ottaviani, Abdallah Lyoussi, Christophe Destouches, Vladimir Radulović, Luka Snoj, Adrien Volte, Michel Carette, and Christelle Reynard-Carette
EDP Sciences
Accurate online in-core parameter measurements, such as neutron and photon fluxes and nuclear heating rates, are essential for fusion and fission applications. Wide bandgap semiconductors, particularly Silicon Carbide (SiC), have demonstrated strong potential for radiation detection over six decades. Despite this, challenges persist in optimizing detector performance under extreme in-core conditions. Our study focuses on 4H-SiC-based detectors, developed within a joint laboratory between Aix-Marseille University and the CEA, aiming to address these challenges and provide high-precision measurements for advanced nuclear facilities. Following previous measurements in ZPRs and with D-T neutron generators, this paper focuses on in-core experimental results obtained with such detectors in the Triangular Irradiation Channel (TIC) of the TRIGA Mark II-type research reactor at the Jožef Stefan Institute (JSI) in Slovenia. These in-core measurements were done by using two types of diodes. One with a Neutron Converter Layer (NCL) of Boron-10 for thermal neutron detection, and the other one without NCL in order to discriminate thermal and fast neutrons by studying 10B reaction versus scattering. Thanks to various Pulse Shape Analyses (PSA) and count rate studies the influence of bias voltage, NCL and neutron fluence on the detector performances were determined. The highest neutron flux and fluence for these detectors were reached: 1.2 × 1013 cm−2·s−1 and 1.2 × 1017 cm−2, respectively.
A. Chomiczewska, T. Tala, W. Gromelski, I. Ivanova-Stanik, E. Kowalska-Strzęciwilk, N. Wendler, I.S. Carvalho, P. Carvalho, I. Coffey, A. Kirjasuo,et al.
IOP Publishing
Abstract The behaviour of impurities in fusion plasmas is of crucial importance for achieving sustained fusion reactions, and understanding similarities and differences between Deuterium (D) and Tritium (T) plasmas is needed to assess potential changes from DD to DT in ITER and future reactors. The first dimensionless and dimensional isotope identity experiments between Deuterium (D) and Tritium (T) L-mode plasmas were conducted at the JET W/Be wall. In the first approach, the discharges with matched ρ∗, ν∗, β n, q, and T e/T i were compared to emphasize direct isotope effects, while in the dimensional approach engineering parameters such as toroidal magnetic field B T, plasma current I p, plasma electron density and NBI power P NBI were matched. The dimensionless isotope scaling showed an improvement in global confinement and local transport in T plasmas in comparison to the matched D one (Cordey et al 1999 Nucl. Fusion 39 301). Detailed impurity analyses using VUV, visible spectroscopy, SXR cameras, and bolometry revealed that T plasmas exhibited higher radiation and impurity content, particularly Ni and W, compared to D plasmas. Understanding the origin of the increased impurity content is addressed in this paper. The dimensionless experiments showed differences in impurity transport. The Be source behaviour varied: D plasmas had higher Be influx in the dimensionless approach due to lower electron density and enhanced sputtering (Saibene et al 1999 Nucl. Fusion 39 1133), while T plasmas showed a higher Be source in the dimensional experiments, highlighting isotope mass effects. W in the divertor region was not sputtered by hydrogen isotopes. W in the divertor region was not sputtered by hydrogen isotopes. In the dimensionless experiments, W sputtering was primarily influenced by Ni in T plasmas and by Be in D plasmas. However, in the dimensional approach, Be played a more significant role in W sputtering within T plasmas. MHD instabilities, including ST oscillations, were present in all cases other ones were correlated with NBI power levels; higher NBI power led to elevated levels of Be, Ni, and W impurities. The comprehensive comparison underscores the necessity of accounting for isotope mass effects in predictive modelling and optimization of plasma performance in fusion reactors.
M. Kong, E. Nardon, D. Bonfiglio, M. Hoelzl, D. Hu, , , and
IOP Publishing
Abstract Mechanisms of plasmoid drift following massive material injection are studied via 3D non-linear MHD modelling with the JOREK code, using a transient neutral source deposited at the low field side midplane of a JET H-mode plasma to clarify basic processes and compare with existing theories. The simulations confirm the important role of the propagation of shear Alfvén wave (SAW) packets from both ends of the plasmoid (‘SAW braking’) and the development of external resistive currents along magnetic field lines (‘Pégourié braking’) in limiting charge separation and thus the E × B plasmoid drift, where E and B are the electric and magnetic fields, respectively. The drift velocity is found to be limited by the SAW braking on the few microseconds timescale for cases with relatively small source amplitude while the Pégourié braking acting on a longer timescale is shown to set in earlier with larger toroidal extent of the source, both in good agreement with existing theories. The simulations also identify the key role of the size of the E × B flow region on plasmoid drift and show that the saturated velocity caused by dominant SAW braking agrees well with theory when considering an effective pressure within the E × B flow region. The existence of SAWs in the simulations is demonstrated and the 3D picture of plasmoid drift is discussed.