Luka Snoj
@ijs.si
Faculty of Mathematics and Physics, University of Ljubljana
Jozef Stefan Institute
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
V. Sola, I. Mandić, K. Ambrožič, O.A. Marti Villarreal, M. Ferrero, G. Kramberger, and L. Snoj
Elsevier BV
Igor Lengar, Theodora Vasilopoulou, Mariusz Kłosowski, Rosaria Villari, Bor Kos, Aljaž Čufar, Domen Kotnik, and Luka Snoj
Elsevier BV
Štefan Čerba, Ján Haščík, Jakub Lüley, Branislav Vrban, Vladimir Radulović, Anže Jazbec, Luka Snoj, Ľubomír Sklenka, Marcel Miglierini, Szabolcs Czifrus,et al.
Elsevier BV
I. Švajger, D. Čalič, A. Pungerčič, A. Trkov, and L. Snoj
Elsevier BV
Tanja Goričanec, Andrej Kavčič, Marjan Kromar, and Luka Snoj
Elsevier BV
Arne Bratkic, Anze Jazbec, Natasa Toplak, Simon Koren, Sonja Lojen, Tinkara Tinta, Rok Kostanjsek, and Luka Snoj
Informa UK Limited
H. Weisen, P. Blanchard, M. Vallar, A. N. Karpushov, J. Dubray, A. Merle, B. P. Duval, J. Cazabonne, D. Testa, H. Hamac Elaian,et al.
Informa UK Limited
Arran George Plant, Bor Kos, Anže Jazbec, Luka Snoj, Malcolm John Joyce, and Vesna Najdanovic-Visak
American Chemical Society (ACS)
Despite offering low-carbon and reliable energy, the utilization of nuclear energy is declining globally due to high upfront capital costs and longer returns on investments. Nuclear cogeneration of valuable chemicals from waste biomass-derived feedstocks could have beneficial impacts while harnessing the underutilized resource of ionizing energy. Here, we demonstrate selective methanol or acetaldehyde production from ethylene glycol, a feedstock derived from glycerol, a byproduct of biodiesel, using irradiations from a nuclear fission reactor. The influence of radiation quality, dose rate, and the absorbed dose of irradiations on radiochemical yields (G-value) has been studied. Under low-dose-rate, γ-only radiolysis during reactor shutdown rate (<0.018 kGy min–1), acetaldehyde is produced at a maximum G-value of 8.28 ± 1.05 μmol J–1 and a mass productivity of 0.73 ± 0.06% from the 20 kGy irradiation of neat ethylene glycol. When exposed to a high-dose-rate (6.5 kGy min–1), 100 kGy mixed-field of neutron + γ-ray radiations, the radiolytic selectivity is adjusted from acetaldehyde to generate methanol at a G-value of 2.91 ± 0.78 μmol J–1 and a mass productivity of 0.93 ± 0.23%. Notably, utilizing 422 theoretical systems could contribute to 4.96% of worldwide acetaldehyde production using a spent fuel pool γ-ray scheme. This research reports G-values and production capacities for acetaldehyde for high-dose scenarios and shows the potential selectivity of a nuclear cogeneration process to synthesize chemicals based on their irradiation conditions from the same reagent.
Samo Gerkšič, Damir Vrančić, Dušan Čalič, Gašper Žerovnik, Andrej Trkov, Marjan Kromar, and Luka Snoj
Elsevier BV
Ankita Sarkar, Matej Šadl, Anže Jazbec, Luka Snoj, Silvo Drnovšek, Tadej Rojac, Geoff L Brennecka, Hana Uršič, and Barbara Malič
IOP Publishing
Abstract The influence of neutron and gamma irradiation on the low- and high-field dielectric and electrocaloric (EC) properties of Mn-doped 0.9Pb(Mg1/3Nb2/3)O3–0.1PbTiO3 (PMN–10PT) ceramic is studied. Upon exposure to neutron fluences of up to 1017 cm−2 and gamma-ray doses of up to 1200 kGy the Mn-doped PMN–10PT exhibits a lower saturated polarization, increased internal bias field and reduced EC temperature change. In comparison, the respective properties of the undoped PMN–10PT remain almost unchanged upon exposure to neutrons and gamma rays. In Mn-doped PMN–10PT, the acceptor-oxygen vacancy defect complexes, introduced via doping, contribute to the lowering of the threshold radiation dose that the material survives without noticeable changes in properties. Radiation-induced degradation of the EC response of Mn-doped PMN–10PT can be partially healed by annealing at 450 °C. The study provides guidance for designing EC ceramic materials for solid-state cooling applications in environments of high ionizing radiation, such as the medical field or space technologies.
Anže Pungerčič, Valerio Mascolino, Alireza Haghighat, and Luka Snoj
Elsevier BV
Domen Kotnik, Anil Kumar Basavaraj, Luka Snoj, and Igor Lengar
Elsevier BV
M. Fortuna, P. Blanchard, A. Čufar, M. Vallar, H. Weisen, A. Žohar, and L. Snoj
Elsevier BV
Robert Bernat, Tihomir Knežević, Vladimir Radulović, Luka Snoj, Takahiro Makino, Takeshi Ohshima, and Ivana Capan
MDPI AG
We report on the effects of large-area 4H-SiC Schottky barrier diodes on the radiation response to ionizing particles. Two different diode areas were compared: 1 mm × 1 mm and 5 mm × 5 mm. 6LiF and 10B4C films, which were placed on top of the diodes, were used as thermal neutron converters. We achieved a thermal neutron efficiency of 5.02% with a 6LiF thermal neutron converter, which is one of the highest efficiencies reported to date. In addition, a temperature-dependent radiation response to alpha particles was presented. Neutron irradiations were performed in a JSI TRIGA dry chamber and an Am-241 wide-area alpha source was used for testing the alpha response of the 4H-SiC Schottky barrier diodes.
Gašper Žerovnik, Dušan Čalič, Samo Gerkšič, Marjan Kromar, Jan Malec, Anže Mihelčič, Andrej Trkov, and Luka Snoj
Frontiers Media SA
Previous work done on reactor kinetics and control in load-following operation modes available in open literature is reviewed. The analysis is focused on, however not limited to pressurized water reactors. Different approximations of the time-dependent neutron transport problem as well as different control algorithms are described in detail and compared. Due to lack of published information the majority of the comparisons was done on qualitative level. In order to facilitate future testing and intercomparisons of models and algorithms, two so-called reference scenarios with time-dependent power demand are defined: a scenario to test the limitations of the load-following capabilities of the nuclear facilities and a second, quasi-realistic scenario.
Tanja Goričanec, Bor Kos, Klemen Ambrožič, Andrej Trkov, Luka Snoj, and Marjan Kromar
Frontiers Media SA
In a typical pressurized water reactor, neutron detectors located outside the reactor core monitor reactor power. In addition, they are also used to measure the reactivity of the control rods. A novel approach to calculate the ex-core neutron detector response in a typical pressurized water reactor using the Monte Carlo technique is presented. A detailed ex-core model of the Krško nuclear power plant was developed using the Monte Carlo neutron transport code MCNP. Due to the location of the ex-core neutron detectors, the hybrid code ADVANTG is used to generate variance reduction parameters to accelerte the convergence of the results outside the reactor core. To use ADVANTG, the fixed neutron source had to be reconstructed from the criticality core calculation. This paper presents the sensitivity analysis of the response of the ex-core detectors to the neutron data libraries used, the description of the fixed neutron source and the ADVANTG parameters. It was found that a pin-wise description of the neutron source for at least two rows of fuel assemblies at the core periphery is necessary for accurate results. Our results show the importance of a correct description of the prompt neutron spectra in the high energy region and the impact this has on the response of the ex-core detectors. The method in which the prompt neutron fission spectra for important fission nuclides are weighted by the calculated reaction rates has been shown to be the best approximation, with deviations from the reference calculation within statistical uncertainty. The effect of nuclear data libraries on the response of the ex-core detector was investigated, and the difference between the ENDF/B-VII.0 and the ENDF/B-VIII.0 nuclear data libraries was ∼11%. When the deficient evaluation of the 56Fe isotope included in the ENDF/B-VIII.0 nuclear data library was replaced by the improved evaluation from the IAEA INDEN project, the differences decreased to ∼3.7%. In addition, neutron flux redistributions due to control rod movement were investigated and flux redistribution factors were updated using Monte Carlo particle transport methods. The reaction rate redistribution factors obtained with methods presented in this paper are within 1% agreement with the currently used factors.
Tihomir Knežević, Tomislav Brodar, Vladimir Radulović, Luka Snoj, Takahiro Makino, and Ivana Capan
IOP Publishing
Abstract We report on the low-energy electron and fast neutron irradiated 4H-SiC studied by deep-level transient spectroscopy (DLTS) and Laplace DLTS. Irradiations introduced two defects, E c −0.4 eV and E c −0.7 eV. They were previously assigned to carbon interstitial (Ci) labeled as EH1/3 and silicon-vacancy (V Si) labeled as S1/2, for the low-energy electron and fast neutron irradiation, respectively. This work demonstrates how Laplace DLTS can be used as a useful tool for distinguishing the EH1 and S1 defects. We show that EH1 consists of a single emission line arising from the Ci(h), while S1 has two emission lines arising from the V Si(h) and V Si(k) lattice sites.
Hana Uršič, Uroš Prah, Tadej Rojac, Anže Jazbec, Luka Snoj, Silvo Drnovšek, Andraž Bradeško, Anja Mirjanić, Marko Vrabelj, and Barbara Malič
Elsevier BV
J. Vega, A. Murari, S. Dormido-Canto, G. A. Rattá, M. Gelfusa, J. Mailloux, N. Abid, K. Abraham, P. Abreu, O. Adabonyan,et al.
Nature Physics Springer Science and Business Media LLC
S. Mazzi, J. Garcia, D. Zarzoso, Ye. O. Kazakov, J. Ongena, M. Dreval, M. Nocente, Ž. Štancar, G. Szepesi, J. Eriksson,et al.
Nature Physics Springer Science and Business Media LLC
Gasper Razdevsek, Urban Simoncic, Luka Snoj, and Andrej Studen
Walter de Gruyter GmbH
Abstract Introduction Potential changes in patient anatomy during proton radiotherapy may lead to a deviation of the delivered dose. A dose estimate can be computed through a deformable image registration (DIR) driven dose accumulation. The present study evaluates the accumulated dose uncertainties in a patient subject to an inadvertent breathing associated motion. Materials and methods A virtual lung tumour was inserted into a pair of single participant landmark annotated computed tomography images depicting opposite breathing phases, with the deep inspiration breath-hold the planning reference and the exhale the off-reference geometry. A novel Monte Carlo N-Particle, Version 6 (MCNP6) dose engine was developed, validated and used in treatment plan optimization. Three DIR methods were compared and used to transfer the exhale simulated dose to the reference geometry. Dose conformity and homogeneity measures from International Committee on Radioactivity Units and Measurements (ICRU) reports 78 and 83 were evaluated on simulated dose distributions registered with different DIR algorithms. Results The MCNP6 dose engine handled patient-like geometries in reasonable dose calculation times. All registration methods were able to align image associated landmarks to distances, comparable to voxel sizes. A moderate deterioration of ICRU measures was encountered in comparing doses in on and off-reference anatomy. There were statistically significant DIR driven differences in ICRU measures, particularly a 10% difference in the relative D98% for planning tumour volume and in the 3 mm/3% gamma passing rate. Conclusions T he dose accumulation over two anatomies resulted in a DIR driven uncertainty, important in reporting the associated ICRU measures for quality assurance.
Hubert Carcreff, Vladimir Radulović, Damien Fourmentel, Klemen Ambrožič, Christophe Destouches, Luka Snoj, and Nicolas Thiollay
Elsevier BV
A. Žohar, M. Nocente, B. Kos, Ž. Štancar, M. Rebai, D. Rigamonti, T. Craciunescu, M. Gorelenkova, Ye.O. Kazakov, V.G. Kiptily,et al.
IOP Publishing
Abstract A novel modelling methodology has been developed for the creation of a realistic plasma gamma-ray source for Monte Carlo transport simulations in the tokamak JET. The methodology couples the TRANSP code for plasma transport calculations with the MCNP Monte Carlo particle transport code, thus connecting plasma physics with gamma-ray transport. This paper presents the validation of the developed source methodology by comparing calculated gamma-ray spectra with measurements performed at JET. The validation focuses on gamma-ray spectra measured by the tangential gamma-ray spectrometer during two JET three ion RF scenario discharges, performed in the JET 2019 deuterium experimental campaign. For validation the calculated plasma gamma-ray spectrum was combined with the neutron induced prompt gamma-ray background, originating in the vacuum vessel, and scaled to absolute values calculating the total number of plasma gamma-ray and neutron emitting reactions. The comparison between calculated and measured gamma-ray spectra shows good agreement with the shape of the calculated gamma-ray spectra matching that of measurements for both studied discharges. Moreover, the calculated absolute values of the gamma-ray spectra were of the same order of magnitude at the position of the gamma-ray detector located at the end of a long line-of-sight in a biological shield. The comparison has validated the developed plasma gamma-ray source methodology for MCNP photon transport calculations at JET. The validation provides a basis for the developed plasma gamma-ray source to be used as a support for the development of future tokamaks such as DEMO.
J. Mailloux, N. Abid, K. Abraham, P. Abreu, O. Adabonyan, P. Adrich, V. Afanasev, M. Afzal, T. Ahlgren, L. Aho-Mantila,et al.
Nuclear Fusion IOP Publishing
Abstract The JET 2019–2020 scientific and technological programme exploited the results of years of concerted scientific and engineering work, including the ITER-like wall (ILW: Be wall and W divertor) installed in 2010, improved diagnostic capabilities now fully available, a major neutral beam injection upgrade providing record power in 2019–2020, and tested the technical and procedural preparation for safe operation with tritium. Research along three complementary axes yielded a wealth of new results. Firstly, the JET plasma programme delivered scenarios suitable for high fusion power and alpha particle (α) physics in the coming D–T campaign (DTE2), with record sustained neutron rates, as well as plasmas for clarifying the impact of isotope mass on plasma core, edge and plasma-wall interactions, and for ITER pre-fusion power operation. The efficacy of the newly installed shattered pellet injector for mitigating disruption forces and runaway electrons was demonstrated. Secondly, research on the consequences of long-term exposure to JET-ILW plasma was completed, with emphasis on wall damage and fuel retention, and with analyses of wall materials and dust particles that will help validate assumptions and codes for design and operation of ITER and DEMO. Thirdly, the nuclear technology programme aiming to deliver maximum technological return from operations in D, T and D–T benefited from the highest D–D neutron yield in years, securing results for validating radiation transport and activation codes, and nuclear data for ITER.
Valerio Mascolino, Alireza Haghighat, and Luka Snoj
Elsevier BV