Search Results (118)

The development of radiation-protective materials with high resistance under reactor irradiation conditions is one of the urgent tasks in modern nuclear technologies. Ultra-high molecular weight polyethylene (UHMWPE) is considered a promising matrix material due to its high hydrogen content, low density, and strong chemical resistance. Composite samples were fabricated by flame formation and irradiated in the IVG-1M research reactor of the National Nuclear Center of the Republic of Kazakhstan. Their neutron absorption capacity, bending strength, and chemical resistance were measured before and after irradiation. The results show that H₃BO₃ provides the strongest contribution to the increase in the neutron absorption coefficient, with the maximum effect observed at 30% filler content. Reactor irradiation caused only a moderate reduction in the composites’ bending strength. Chemical resistance tests confirmed that UHMWPE-based composites with WC and PbO retain stability in aggressive environments, even after reactor exposure. Overall, UHMWPE-based composites containing boron and heavy-element fillers demonstrate strong potential as radiation-protective materials. Their design should account not only for neutron absorption efficiency but also for mechanical strength and chemical resistance under reactor operating conditions. Full article

Boron (B) is widely used as a neutron-absorbing nuclide and has significant applications in the nuclear industry. B₄C/Al composites combine the high hardness of B₄C with the ductility of Al, making them commonly used neutron-absorbing materials. Under current preparation methods, the poor wettability and low reactivity of B₄C with molten Al limit its effective incorporation into the matrix, and the addition of B₄C in B₄C/Al composites has reached its threshold limit, making it difficult to achieve breakthrough improvements in neutron absorption performance. However, incorporating additional B elements into the B₄C/Al composite can break this limit, effectively enhancing the material’s neutron absorption performance. Nevertheless, research on the impact of this addition on the mechanical properties of the composite remains unclear. The requirements for B₄C/Al composites as spent fuel storage and transportation devices include high mechanical strength and certain machinability. This study fabricated B₄C/Al composites with varying B contents (5 wt.%, 10 wt.%, and 15 wt.%), and the influence of B addition on the microstructure and mechanical properties of B₄C/Al composites was investigated. The results demonstrate that the composites exhibit a density of approximately 99% with well-established interfacial bonds. Increasing B content leads to a higher quantity of interfacial reaction products Al₃BC and AlB₂, enhancing the Vickers hardness to 370.93 HV. The bending strength and fracture toughness of composites with 5 wt.% and 15 wt.% B addition decreased, whereas those with 10 wt.% B exhibited excellent resistance to crack growth and high-temperature plastic deformation due to a high content of ductile phase. Full article

This work investigates a ⁴He-detector active interrogation system that leverages neutron spectroscopy to classify nuclear waste streams. MCNP models tested the concept through the simulation of a D-D neutron generator, an array of ⁴He detectors, and various waste compositions. The fast-neutron Differential Die-Away signature was augmented with a neutron-energy discrimination signature. This signature isolates induced fission neutrons, the energy of which is greater than that of the D-D monoenergetic spectrum. With the incorporation of this spectroscopic technique, the measurement time decreased by 3–9% (depending on the degree of neutron moderation and absorption presented by the sample), demonstrating how neutron spectroscopy can enhance active interrogation methods. The reduced measurement times would have significant financial and logistical benefits for facilities with large footprints of low-level waste production. Full article

Hexagonal boron nitride (h-BN), a wide-bandgap semiconductor with excellent thermal stability, high electrical resistivity, and strong neutron absorption capacity, has attracted growing interest in the field of solid-state neutron detection. This review summarizes the progress in h-BN crystal growth technologies, including HPHT, CVD, and flux methods, highlighting their advantages and limitations. Among them, flux growth stands out for its simplicity and scalability in producing high-quality, large-area single crystals. The application potential of h-BN in next-generation neutron detectors is also discussed, along with key challenges such as ¹⁰B enrichment, crystal quality, and device integration. Full article

In this work, we report the identification of a novel quaternary intermetallic phase (Al₂₁GdCrTi) formed during the solidification of a novel Al-Gd-Cr-Ti alloy, which has not been previously documented in the literature to the best of our knowledge. The study also provides a detailed analysis of microstructure evolution, texture behavior, and the mechanical strengthening effect of rolling processes, along with neutron absorption performance. XRD analysis reveals that the intensity of (022), (113) planes of the as-hot-cold-rolled sample is higher than that of the as-cast due to the change in the direction of some grains in these planes during rolling. The results indicate that the studied alloys scatter neutrons about 100 times less than a nearly pure aluminum alloy. The hardness of the as-cast alloy increased from 36 to 53 HV after cold rolling and to 50 HV after hot rolling-cold rolling. Hot-cold-rolled alloy has a yield strength of 160 MPa and an ultimate tensile strength of 181 MPa, while maintaining an elongation of 11.3%. The studied alloys, containing 4.2 wt.% of the alloying elements 3.8Gd, 0.2Cr, and 0.2Ti (Al-3.8Gd-0.2Cr-0.2Ti), exhibited a yield strength 28 MPa higher than those containing 21 wt.% of the alloying elements 5Cu, 6Gd, and 8Bi (Al-5Cu-6Gd-8Bi). The studied alloys form the basis for the development of high-technology Al-Gd alloys for neutron shielding. Full article

The recovery of radiation damage induced by 231-MeV xenon ions with varying fluence (from 5 × 10¹¹ to 2 × 10¹⁴ cm⁻²) in α-Al₂O₃ (corundum) single crystals has been studied by means of isochronal thermal annealing of radiation-induced optical absorption (RIOA). The integral of elementary Gaussians (product of RIOA spectrum decomposition) OK has been considered as a concentration measure of relevant oxygen-related Frenkel defects (neutral and charged interstitial-vacancy pairs, F-H, F⁺-H⁻). The annealing kinetics of these four ion-induced point lattice defects has been modelled in terms of diffusion-controlled bimolecular recombination reactions and compared with those carried out earlier for the case of corundum irradiation by fast neutrons. The changes in the parameters of interstitial (mobile component in the recombination process) annealing kinetics—activation energy E and pre-exponential factor X—in ion-irradiated crystals are considered. Full article

This study evaluated the impact of mill scale (MS), a steel manufacturing waste product, as a replacement for natural fine aggregate (up to 100% by volume) in high-calcium fly ash-based geopolymer concrete (GC) and ordinary Portland cement concrete (CC). We compared the workability, compressive strength, splitting tensile strength, modulus of elasticity, density, water absorption, porosity, ultrasonic pulse velocity, thermal conductivity, acid resistance, chloride penetration, and radiation attenuation (gamma rays and fast neutrons) of the resulting materials. Results showed that GC and CC with 100% MS achieved 28-day compressive strengths of 23.6 MPa and 35.2 MPa, respectively, representing 58% and 90% of the strengths of plain GC and CC. MS-modified GC exhibited superior acid and chloride resistance compared to CC. Importantly, MS enhanced radiation shielding, with GC and CC containing 100% MS, demonstrates the best performance, suggesting its potential use in radiation-shielding construction materials. Full article

Boron neutron capture therapy (BNCT) is a specialized cancer treatment that leverages the high absorption cross-section of boron for thermal neutrons. When boron captures neutrons, it undergoes a nuclear reaction that produces alpha particles and lithium ions, which have high linear energy transfer (LET) and can effectively damage nearby cancer cells while minimizing harm to surrounding healthy tissues. This targeted approach makes BNCT particularly advantageous for treating tumors situated in sensitive areas where traditional radiation therapies may pose risks to critical structures. In this study, the deuterium–deuterium (DD) neutron generator, specifically the DD-110 model (neutron yield Y = 1 × 10¹⁰ n/s), served as the neutron source for BNCT. The fast neutrons produced by this generator were thermalized to the epithermal energy range using a beam-shaping assembly (BSA). The BSA was designed with a moderator composed of 32 cm of MgF₂, a reflector made of 76 cm of Pb, and filters including 3 cm of Pb and 1.52 cm of Bi. A collimator, featuring a 10 cm high Pb cone frustum with a 12 cm aperture diameter, was also employed to optimize beam characteristics. The entire system’s performance was modeled and simulated using the MCNPX code, focusing on parameters both in-air and in-phantom to evaluate its efficacy. The findings indicated that the BSA configuration yielded an optimal thermal-to-epithermal flux ratio (${\phi }_{ther}$/${\phi }_{epth}$) of 0.19, a current-to-flux ratio of 0.87, and a gamma dose-to-epithermal flux ratio of 1.71 × 10⁻¹³ Gy/cm², all aligning with IAEA recommendations. The simulated system showed acceptable ratios for ${\phi }_{ther}$/${\phi }_{epth}$, gamma dose to epithermal flux, and beam collimation. Notably, the advantage depth was recorded at 5.5 cm, with an advantage ratio of 2.29 and an advantage depth dose rate of 4.1 × 10⁻⁴ Gy.Eq/min. The epithermal neutron flux of D110 exceeded D109, but D110’s fast neutron contamination increased ~6.6 times. On the other hand, D110’s gamma contamination decreased by 30%. Based on these findings, optimizing neutron source characteristics is crucial for BNCT efficacy. Future research should focus on developing advanced neutron generators that balance these factors, aiming to produce optimal neutron yields for enhanced treatment outcomes and broader applicability. Full article

A single crystal of YAl₃(BO₃)₄ was grown using the top-seeded solution growth method. The vacuum ultraviolet (VUV) excitation spectrum, monitored at the emission wavelength of 312 and 372 nm, showed a narrow excitation band at around 162 nm, which is located near the absorption edge of the YAl₃(BO₃)₄ host. Upon VUV excitation at 162 nm, the characteristic self-trapped exciton (STE) emission bands were observed at 312 and 372 nm. The X-ray excited scintillation spectrum shows a broad emission band peaking at 310 nm with a weak shoulder band at around 375 nm, which is consistent with photoluminescence, and can thus be assigned to the STE emission. The scintillation light yield under irradiation at a ²⁵²Cf-thermal neutron reached 2700 photons/thermal neutron. Full article

In this study, the microstructure and corrosion behavior of gas tungsten arc (GTA) welds of borated stainless steel (BSS) with a boron content of 1.62 wt.% were investigated using various filler metals. The filler metals used in this study were 308L, 309L, and 310 without the B component. A small amount of the B component was observed in the weld metal (WM) of all specimens, even though none of the filler wires contained boron. This result was caused by the dilution of the B component from the BM into the WM by the welding heat. The segregation of boron in the WM resulted in Cr-depleted areas, which negatively affected the corrosion resistance of the welded specimens. The corrosion resistance of 308L WM with the highest fraction of B components was the most deteriorated, whereas 309L WM with the lowest boron content exhibited the best corrosion resistance. Using a filler metal without the B component is expected to effectively improve the weldability and corrosion resistance of BSS; however, it can also reduce the neutron absorption capacity. Therefore, for BSS to be used as a spent nuclear fuel storage container material, the boron content of the filler metal must be carefully considered. This study provides a foundation for research aimed at improving the development and applicability of filler metals in borated stainless steel and makes it competitive for application in fourth-generation nuclear power systems. Full article

To fulfill the needs of neutron capture reaction cross-section measurement in the keV energy region in the field of nuclear astrophysics and advanced nuclear energy system development, the 4π BaF_2 Gamma-Ray Total Absorption Facility (GTAF) developed by the Key Laboratory of Nuclear Data of the China Institute of Atomic Energy (CIAE) was transplanted and installed at the Back-streaming White Neutron Source (Back-n) of the China Spallation Neutron Source (CSNS) in 2019. A series of results has been achieved and published based on the GTAF since then, and it has been identified that the need of reducing backgrounds is becoming increasingly urgent. In order to understand the origins of backgrounds and to optimize the facilities, a detailed simulation program using GEANT4 toolkits was established and is presented in this paper. The symmetry in the geometric arrangement of the 4π BaF₂ detector array plays a critical role in ensuring uniform detection efficiency and accurate reconstruction of gamma-ray spectra, which is essential for neutron capture studies. To demonstrate the availability of the proven codes, several practical examples of assisting the process of experimental data and helping verify the optimization proposition are also shown in this paper. Full article

This work presents the results of a study on the influence of fillers on the neutron absorption capacity of materials made from ultra-high molecular weight polyethylene (UHMWPE). Composite materials based on UHMWPE were obtained using gas-flame technology with the addition of powdered UHMWPE fillers (H₃BO₃, WC, and PbO). A radiation cassette has been developed and constructed for conducting studies on the neutron absorption capacity of the material, allowing for the placement of a sample with activation indicators. Samples of UHMWPE with fillers were irradiated at different doses on the unique research reactor IVG-1M, located at the National Nuclear Center of the Republic of Kazakhstan in the city of Kurchatov. The reaction rate of ⁶³Cu (n, g), ⁶⁴Cu and ⁵⁸Ni (n, p)⁵⁸Co on activation indicators and neutron flux density at the sample location were determined. Neutron-physical and thermal-physical calculations were performed in order to determine their characteristics. The structure and phase state of UHMWPE with fillers were studied before and after irradiation. Full article

The permeation of tritium from secondary neutron source rods in nuclear power plants presents a significant and unavoidable safety concern both for internal equipment and the external environment. This study primarily explores two feasible strategies for tritium permeation barriers: coating stainless steel surfaces with tritium permeation barrier (TPB) materials and utilizing materials with excellent tritium absorption properties. Through external ion irradiation tests, a comparative analysis was conducted on the tritium permeation performance, morphology, and nanohardness changes in two tritium-resistant designs, specifically Cr₂O₃/Al₂O₃ composite coatings and a zirconium-based tritium-absorbing material under varying irradiation doses. The results indicate that both approaches exhibit exceptional radiation resistance, maintaining an effective tritium permeation reduction factor (PRF) even after irradiation. Full article

This article considers the prospects of using heat-resistant polyimide boron-containing composites to protect astronauts of manned orbital stations from secondary neutron radiation. Variant calculations are performed regarding neutron and gamma-quanta flux distributions in a polyimide composite material with different boron content used to reduce capture radiation. The dependences of spatial distributions of thermal neutron flux density and the gamma-quanta dose rate in a polyimide composite layer with a boron content of 0 to 5% are obtained. An experimental assessment of the energy distribution of neutron and gamma radiation behind the protective polyimide composite is carried out. The introduction of boron atoms in an amount of 3.0 wt.% shows the absence of bursts of secondary gamma radiation energy in the composite, which is due to the high cross-section of thermal neutron absorption by boron atoms. As a result, with a material layer thickness of 3–10 cm, the gamma-quanta dose rate decreases by 2–3 times. The differential thermal analysis method showed that the upper limit of the working temperature of the polyimide composite is 500 °C. The polyimide matrix filled with boron atoms can find effective application in the development of new radiation-protective polymer materials used in manned orbital stations. Full article

The Two-Photon Absorption–Transient Current Technique (TPA-TCT) is a device characterisation technique that enables three-dimensional spatial resolution. Laser light in the quadratic absorption regime is employed to generate excess charge carriers only in a small volume around the focal spot. The drift of the excess charge carriers is studied to obtain information about the device under test. Neutron-, proton-, and gamma-irradiated p-type pad silicon detectors up to equivalent fluences of about 7 × 10¹⁵ ${\mathrm{n}}_{\mathrm{eq}}/\mathrm{c}{\mathrm{m}}^2$ and a dose of $186 \mathrm{M}\mathrm{r}\mathrm{a}\mathrm{d}$ are investigated to study irradiation-induced effects on the TPA-TCT. Neutron and proton irradiation lead to additional linear absorption, which does not occur in gamma-irradiated detectors. The additional absorption is related to cluster damage, and the absorption scales according to the non-ionising energy loss. The influence of irradiation on the two-photon absorption coefficient is investigated, as well as potential laser beam depletion by the irradiation-induced linear absorption. Further, the electric field in neutron- and proton-irradiated pad detectors at an equivalent fluence of about 7 × 10¹⁵ ${\mathrm{n}}_{\mathrm{eq}}/\mathrm{c}{\mathrm{m}}^2$ is investigated, where the space charge of the proton-irradiated devices appears inverted compared to the neutron-irradiated device. Full article