<abstract><title style='display:none'>Abstract</title> The experiments were carried out in the PF-1000 plasma-focus device at the maximum current reaching about 2 MA, at the deuterium or neon filling and with deuterium injected from a gas-puff nozzle placed on the axis of the anode face. Ball-like structures of diameters of 1-12 mm were identified in interferometric and XUV pinhole camera frames. We made the statistical description of their parameters. A lifetime of the ball-like structures was in the range from 30 to 210 ns, and in some cases even more. These structures appeared mostly at the surface of the imploding plasma shell and they did not change their position in relation to the anode end. During the evolution of these structures, interferometric fringes were observed near the surfaces of the structures only, and their internal parts were initially chaotic (without noticeable) fringes. Subsequently the number of interferometric fringes increased (the internal ‘chaotic’ area was filled with fringes too) and later on it decreased. The radii of the ball-like structures were mostly increasing during their existence. The maximum electron density reached the value of 1024 to 1025 m-3. The ball-like structures decayed by absorption inside the expanded pinch column and/or gradually expired in rare plasma outside of the dense plasma column.</abstract>

Faculty of Electrical Engineering, Czech Technical University in Prague (CVUT), Technická 2, 166 27, Prague, Czech Republic

Institute of Plasma Physics and Laser Microfusion (IPPLM), 23 Hery Str., 01-497 Warsaw, Poland

Evolution of the small ball-like structures in the plasma focus discharge

<abstract><title style='display:none'>Abstract</title>Magnesium oxide (MgO) is one of the most important raw materials in many branches of industry. Magnesium oxide is a popular refractory raw material because of its high refractoriness and high resistance to basic slags and environment. In many cases, use of MgO is limited by its properties, especially the presence of secondary phases like iron oxides. The amount and distribution of iron oxides can strongly influence the technological properties of MgO and depend on the manufacturing method, particularly the heat-treatment process. The aim of the study was to evaluate the influence of the heat-treatment process on amount and distribution of iron ions in a magnesium oxide lattice. The 57Fe Mössbauer effect measurements of fused and sintered magnesium oxide samples doped by the iron oxide were conducted. Investigation reveals in both cases the presence of Fe2+ as well as Fe3+ ions. Fe2+ ions occupy Mg2+ octahedral sites in the MgO lattice, whereas the Fe3+ ions are located in highly distorted octahedral coordination. The amount of Fe2+ varies from around 66% for fused samples to 30% for sintered samples.</abstract>

Position of Fe ions in MgO crystalline structure

<abstract><title style='display:none'>Abstract</title>The influence of sandblasting on surface and subsurface of stainless steel is investigated using variable energy positron beam (VEP), positron annihilation spectroscopy (PAS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Samples of stainless steel were blasted using 110 μm particles of Al2O3 under different pressure and time duration. In the case of sandblasting for 90 s, the reduction of positron diffusion length depending on the applied pressure was observed. Sandblasting during 30 s leads only to the reduction of positron diffusion length to about 60 nm for all samples. Positron lifetimes close to 170 ps measured using positrons emitted directly from the source point to the presence of vacancies on the dislocation lines. SEM and AFM images show that surface roughness depends rather on pressure of sandblasting than time of exposition.</abstract>

Joint Institute for Nuclear Research, 6 Joliot Curie Str., 141980 Dubna, Moscow region, Russian Federation and Institute of Nuclear Physics of the Polish Academy of Sciences, 152 Radzikowskiego Str., 31-342 Kraków, Poland

Northern Arctic Federal University, 163002 Severnaya Dvina Emb. 17, Arkhangelsk, Russian Federation

Joint Institute for Nuclear Research, 6 Joliot Curie Str., 141980 Dubna, Moscow region, Russian Federation and Institute of Electrophysics and Radiation Technologies NAS of Ukraine, 28 Chernyshevsky Str., 61002 Kharkov, Ukraine

Studies of stainless steel exposed to sandblasting

<abstract><title style='display:none'>Abstract</title>Rectifier columns are considered to be a critical component in petroleum refineries and petrochemical processing installations as they are able to affect the overall performance of these facilities. It is deemed necessary to monitor the operational conditions of such vessels to optimize processes and prevent anomalies which could pose undesired consequences on product quality that might lead to huge financial losses. A rectifier column was subjected to gamma scanning using a 10-mCi Co-60 source and a 2-inch-long detector in tandem. Several scans were performed to gather information on the operating conditions of the column under different sets of operating parameters. The scan profiles revealed unexpected decreases in the radiation intensity at vapour levels between trays 2 and 3, and between trays 4 and 5. Flooding also occurred during several scans which could be attributed to parametric settings.</abstract>

Performance evaluation of a rectifier column using gamma column scanning

<abstract><title style='display:none'>Abstract</title> The COMPASS tokamak is equipped with the soft X-ray (SXR) diagnostic system based on silicon photodiode arrays shielded by a thin beryllium foil. The diagnostic is composed of two pinhole cameras having 35 channels each and one vertical pinhole camera with 20 channels, which was installed recently to improve tomographic inversions. Lines of sight of the SXR detectors cover almost complete poloidal cross section of the COMPASS vessel with a spatial resolution of 1-2 cm and temporal resolution of about 3 μs. Local emissivity is reconstructed via Tikhonov regularization constrained by minimum Fisher information that provides reliable and robust solution despite limited number of projections and ill-conditionality of this task. Improved border conditions and numerical differentiation matrices suppressing artifacts in reconstructed radiation were implemented in the code. Furthermore, a fast algorithm eliminating iterative processes was developed, and it is foreseen to be tested in real-time plasma control.</abstract>

Institute of Plasma Physics ASCR v.v.i., Faculty of Mathematics and Physics, Charles University in Prague, Za Slovankou 3, 18200 Praha 8, Czechia

Max-Planck-Institut für Plasmaphysik, Technische Universität Munchen, Boltzmannstraße 2, D-85748 Garching,

Optoelectronic Research Center, University of Southampton, University Rd, Southampton SO17 1BJ,

Optimization of soft X-ray tomography on the COMPASS tokamak

<abstract><title style='display:none'>Abstract</title> The nuclear fuel reprocessing is a prerequisite for nuclear energy to be a clean and sustainable energy. In the case of the molten salt reactor containing a liquid fuel, pyrometallurgical way is an obvious way. The method for treatment of the liquid fuel is divided into two parts. In-situ injection of helium gas into the fuel leads to extract the gaseous fission products and a part of the noble metals. The second part of the reprocessing is performed by ‘batch’. It aims to recover the fissile material and to separate the minor actinides from fission products. The reprocessing involves several chemical steps based on redox and acido-basic properties of the various elements contained in the fuel salt. One challenge is to perform a selective extraction of actinides and lanthanides in spent liquid fuel. Extraction of actinides and lanthanides are successively performed by a reductive extraction in liquid bismuth pool containing metallic lithium as a reductive reagent. The objective of this paper is to give a description of the several steps of the reprocessing retained for the molten salt fast reactor (MSFR) concept and to present the initial results obtained for the reductive extraction experiments realized in static conditions by contacting LiF-ThF4-UF4-NdF3 with a lab-made Bi-Li pool and for which extraction efficiencies of 0.7% for neodymium and 14.0% for uranium were measured. It was concluded that in static conditions, the extraction is governed by a kinetic limitation and not by the thermodynamic equilibrium.</abstract>

Pyrochemical reprocessing of molten salt fast reactor fuel: focus on the reductive extraction step

<abstract>
<title style='display:none'>Abstract</title>
The neutronic characteristics of (Th-233U)O2, (Th-233U)C, and (Th-233U)N have been compared in small long-life pressurized water reactors (PWRs). Neutronic calculations were carried out at 300 MWth, 400 MWth, and 500 MWth with two cladding types: zircaloy-4 and ZIRLO (Zr low oxygen). They were performed using the Standard Reactor Analysis Code (SRAC) and JENDL-4.0 nuclide data, dividing the reactor core into three fuel zones with varying 233U enrichment levels, ranging from 3% to 9% and fluctuating by 1%, employing the PIJ module at the fuel cell level and the CITATION module at the reactor core level. In addition, 231Pa was added as burnable poison (BP). The (Th-233U)N fuel demonstrated superior criticality compared to the other fuel types, as it consistently achieves critical conditions throughout the reactor’s operating cycle with excess reactivity &lt;1.00% dk/k for several fuel configurations at the 300 MWth and 400 MWth power levels. Moreover, the (Th-233U)N and (Th-233U)C fuels exhibited similar and flatter power density distribution patterns compared to the (Th-233U)O2 fuel. The power peaking factor (PPF) value was relatively higher for (Th-233U)O2 fuel than the other two fuels. The (Th-233U)N fuel exhibited the most negative Doppler coefficient, followed by (Th-233U)C and (Th-233U)O2 fuels. Analysis of burnup levels revealed that the (Th-233U)O2 fuel achieved significantly higher burnup than the other two fuels.
</abstract>

Comparison of the neutronic properties of the (Th-233U)O2, (Th-233U)C, and (Th-233U)N fuels in small long-life PWR cores with 300, 400, and 500 MWth of power

<abstract>
<title style='display:none'>Abstract</title>
We studied the effects of Aeroxide P25 titanium dioxide nanoparticles (TiO2 NPs) with a diameter of 21 nm on induction of DNA damage and long-term survival of three human cell lines: hepatocellular liver carcinoma HepG2, colorectal adenocarcinoma HT29 and lung carcinoma A549. The endpoints examined were DNA breakage estimated by the comet assay and oxidative base damage recognized by formamide-pyrimidine glycosylase (FPG) estimated with the FPG+ comet assay, frequencies of histone γH2AX foci and micronuclei, apoptosis, cell metabolic activity measured by mitochondrial activity (MTT) assay and long-term survival measured by colony-forming ability. Each cell line had a different pattern of DNA breakage and base damage vs. nanoparticle (NP) concentration and treatment time. There was no increase in the frequencies of histone γH2AX foci and micronuclei as compared to those in the untreated cells. In parallel with these results, no induction of apoptosis has been found in none of the cell lines tested. The reported experiments provided no evidence of the long-term <italic>in vitro</italic> toxicity of Aeroxide P25 TiO2 NPs, despite a slight decrease in mitochondrial activity and cell survival during the first 72 h.
</abstract>

No evidence of the long-term <italic>in vitro</italic> toxicity of Aeroxide P25 TiO2 nanoparticles in three mammalian cell lines despite the initial reduction of cellular mitochondrial activity

<abstract>
<title style='display:none'>Abstract</title>
Lead (Pb)-based materials are very effective in radiation shielding due to their high density of Pb. However, they pose health risks to humans because of the toxicity of lead. As a result, the investigation of radiation shielding properties of various lead-free glass materials has drawn a lot of attention from researchers. In this work, the γ radiation competence of the Bi2O3–ZnO–B2O3–SiO2 glass network was investigated, for the first time in the 0.015–15 MeV energy range, using Phy-X/PSD and XCOM software systems. The results showed that 45Bi2O3–5ZnO–20B2O3–30SiO2 glass sample has the highest linear attenuation coefficient, mass attenuation coefficient, and effective atomic number, and it has the lowest half-value layer, tenth-value layer, and mean-free path. Therefore, 45Bi2O3–5ZnO–20B2O3–30SiO sample is more effective on γ ray shielding than 10Bi2O3–40ZnO–20B2O3–30SiO, 20Bi2O3–30ZnO–20B2O3–30SiO, 30Bi2O3–20ZnO–20B2O3–30SiO, and 40Bi2O3–10ZnO–20B2O3–30SiO samples. The comparison of the results with the literature also revealed that the 45Bi2O3–5ZnO–20B2O3–30SiO glass sample is even more effective than some of Bi2O3-based glass systems, which were recently developed in the literature, by at least a factor of 2.
</abstract>

Gamma radiation shielding properties of (x)Bi2O3–(0.5 – x)ZnO–0.2B2O3–0.3SiO2 glass system

Professor W. Alexander Van Hook (1936-2023)

<abstract>
<title style='display:none'>Abstract</title>
Modelling of the plasma transport for inherently three-dimensional (3D) problems as in stellarators requires dedicated complex codes. FINDIF is a 3D multifluid plasma edge transport code that has been previously successfully used for the analysis of energy transport in the TEXTOR-DED tokamak [<xref ref-type="bibr" rid="j_nuka-2023-0011_ref_001">1</xref>], where 3D perturbations led to an ergodic structure of field lines in the plasma edge. The ongoing efforts to apply it meaningfully to Wendelstein 7-X (W7-X) plasma problems resulted in advancements in the main model and accompanying tools for mesh generation and post-processing. In order to verify the applicability of the code and to compare with the reported simulation (EMC3-EIRENE) and experimental (OP1.1) results, a series of simulations for varying plasma density, temperature and anomalous transport coefficients as well as for fixed input power were performed. The connection length pattern of FINDIF traced magnetic field lines on the limiter was reproduced and its impact on heat loads was confirmed. An increase in the peak heat load on the limiter with a rise in plasma density, temperature and anomalous plasma transport coefficients was observed. The decay lengths of density, electron temperature and heat flux did not change with density, and were decreasing with temperature and increasing with anomalous plasma transport coefficient, which was compared to the simple scrape-off layer (SOL) model.
</abstract>

Numerical studies of plasma edge in W7-X with 3D FINDIF code

<abstract>
<title style='display:none'>Abstract</title>
Ionizing radiation detection in harsh environment conditions often requires additional signal processing to match the requirements of the commercial data readout systems. The subject of this paper is the design of the high-temperature (HT) signal conditioning module that ensures the applicability of scintillation detectors that utilize photomultiplier tubes (PMT) with moderate sampling rate instrumentation. The design was developed for the operation in HT environments (up to 120°C). In order to achieve the optimal signal shape, the module combines a charge amplifier and a low-pass filtering circuitry. An embedded power supply section makes it a complete, standalone unit requiring a single 12 V supplying line. A comprehensive analysis of the developed device, named “PreAmp Shape”, was conducted in order to prove the intended functionality over the different working conditions.
</abstract>

Photomultiplier tube signal conditioning for high-temperature applications

<abstract><title style='display:none'>Abstract</title>In this work the synthesis of hercynite from Fe2O3 and Al2O3 powders was carried out by arc-melting method under the protective argon atmosphere. The obtained material was characterized with the use of powder X-ray diffractometry (XRD) and Mössbauer spectroscopy (MS). A Mössbauer effect in hercynite obtained by the arc-melting method indicated the cations distribution in the spinel structure among the tetrahedral and octahedral interstices. The presence of Fe2+ ions was detected in both tetrahedral and octahedral sites while Fe3+ ions occupied only the octahedral interstices. The approximate formula of the obtained iron-aluminate spinel was as follows (Fe2+0.77Al3+0.23) (Fe3+0.07Fe2+0.05Al0.88)2O4.</abstract>

Department of Ceramics and Refractories, Faculty of Materials Science and Ceramics, AGH – University of Science and Technology, 30 Mickiewicza Ave., 30-059 Kraków, Poland

Mössbauer Spectroscopy Division, Institute of Physics, Pedagogical University, 2 Podchorążych Str., 30-084 Kraków, Poland

Crystal structure and Mössbauer study of FeAl2O4

<abstract><title style='display:none'>Abstract</title>Tungsten is a prime candidate material for the plasma-facing components in future fusion devices, e.g. ITER and DEMO. Because of the harsh and complex loading conditions and the differences in material properties, joining of the tungsten armor to the underlying construction and/or cooling parts is a complicated issue. To alleviate the thermal stresses at the joint, a sharp interface may be replaced by a gradual one with a smoothly varying composition. In this paper, several techniques for the formation of tungsten-steel composites and graded layers are reviewed. These include plasma spraying, laser cladding, hot pressing and spark plasma sintering. Structure, composition and selected thermal and mechanical properties of representative layers produced by each of these techniques are presented. A summary of advantages and disadvantages of the techniques and an assessment of their suitability for the production of plasma-facing components is provided.</abstract>

Overview of processing technologies for tungsten-steel composites and FGMs for fusion applications

<abstract><title style='display:none'>Abstract</title> Small particles of magnetite, i.e. 7.5, 13.4 and 14.1 nm in diameter, were obtained by the method of co-precipitation. The crystal structure and size distributions were determined by means of transmission electron microscopy and X-ray diffraction. The magnetic properties of the nanoparticles were tested by Mössbauer spectroscopy within the temperature range from 3 K to room temperature (RT). The Mössbauer study of magnetic nanoparticles reveals relaxation behaviour related to the existence of the superparamagnetic phase. The blocking temperature depends on the sizes of the nanoparticles and the ammonia concentration.</abstract>

Synthesis and characterization of iron oxide magnetic nanoparticles

<abstract><title style='display:none'>Abstract</title> The paper presents the investigation of magnetic nanoparticles (MNPs) dedicated to hyperthermia application. The crystal structure and size distributions have been determined by means of transmission electron microscope (TEM) and X-ray diffraction (XRD). Magnetic properties of the nanoparticles were tested by Mössbauer spectroscopy together with calorimetric experiments. The Mössbauer spectroscopic study of MNPs revealed the existence of a superparamagnetic phase. The relative contribution of the relaxing component to the total spectrum at room temperature was about 10%. The heating effect of these MNPs under alternating magnetic field was examined. The temperature increase has reached 5°C in 10 min. The preliminary temperature rise suggests that the investigated materials are applicable for hyperthermia.</abstract>

Investigation of magnetite Fe3O4 nanoparticles for magnetic hyperthermia

<abstract><title style='display:none'>Abstract</title>The paper deals with positron porosimetry (PP), which is based on positron annihilation lifetime spectroscopy (PALS). The numerical analysis of positron lifetime spectra for PP is more demanding than in most of other applications of PALS. The resulting intensity distributions of <italic>ortho</italic>-positronium (<italic>o</italic>-Ps) lifetimes are interpreted in terms of the extended Tao-Eldrup (ETE) model, which provides the dependence between the <italic>o</italic>-Ps lifetime and pore size. Additionally, the relation between the intensity of an <italic>o</italic>-Ps component and the pore volume allows obtaining pore size distribution (PSD). The value of the empirical parameter Δ, which is dependent on material, can be estimated from the temperature dependence of an <italic>o</italic>-Ps lifetime. The most unique feature of PP among other techniques that allow determination of PSDs is its ability to perform measurements in almost any conditions. This makes this method suitable for various <italic>in situ</italic> studies. In this review article, both the capabilities and the limitations of PP are discussed. The methods to overcome some of the limitations are presented.</abstract>

Principles of positron porosimetry

<abstract><title style='display:none'>Abstract</title>Many parameters of non-equilibrium plasma generated by high intensity and fast lasers depend on the pulse intensity and the laser wavelength. In conditions favourable for the target normal sheath acceleration (TNSA) regime the ion acceleration from the rear side of the target can be enhanced by increasing the thin foil absorbance through the use of nanoparticles and nanostructures promoting the surface plasmon resonance effect. In conditions favourable for the backward plasma acceleration (BPA) regime, when thick targets are used, a special role is played by the laser focal position with respect to the target surface, a proper choice of which may result in induced self-focusing effects and non-linear acceleration enhancement. SiC detectors employed in the time-of-flight (TOF) configuration and a Thomson parabola spectrometer permit on-line diagnostics of the ion streams emitted at high kinetic energies. The target composition and geometry, apart from the laser parameters and to the irradiation conditions, allow further control of the plasma characteristics and can be varied by using advanced targets to reach the maximum ion acceleration. Measurements using advanced targets with enhanced the laser absorption effect in thin films are presented. Applications of accelerated ions in the field of ion source, hadrontherapy and nuclear physics are discussed.</abstract>

Ion acceleration from intense laser-generated plasma: methods, diagnostics and possible applications

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Nukleonika

The Journal of Instytut Chemii i Techniki Jadrowej

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Nukleonika publish articles from the fields of nuclear sciences especially of nuclear chemistry, radiation chemistry, radiation physics,...