•Proposed a miniaturized radioisotope thermoelectric generator (RTG) with a stacked and radial heat conduction structure.•Used electric heating as an equivalent radioactive isotope heat source.•Fabricated (Bi, Sb)2(Te, Se)3-based thermoelectric modules by screen printing with Isc of 3.5 uA, Voc of 15 mV, and Pmax of 12 nW.•Theoretically predicted the power density for 100-layer modules is 0.51 mW cm−3.A radioisotope thermoelectric generator based on (Bi, Sb)2(Te, Se)3 thermoelectric material was designed as a miniature long-life power supply for low-power devices. In the finite element method simulation, the maximum hot-side temperature is approximately 400 K, and the voltage could reach 0.3 V for one single-layer module at 0.5 W heat source. Thermocouples films were prepared by screen printing. And one single-layer module, which was composed of five thermocouples, produces a power of 12 nW at 7.0 mV in the test. It is predicted that 100-layer modules would generate 2.31 mW at 2.34 V, and the maximum power density and maximum conversion efficiency are 0.51 mW cm−3 and 0.46%, respectively.

•MWCNT arrays were subjected to 540 keV He2+ irradiation under various fluences.•Raman spectra, SEM and TEM images were used to study the morphology of MWCNTs.•The adhesion force of MWCNTs linearly decreases as the irradiation fluence increases.•The instantaneous modulus has a peak value with increasing irradiation fluence.In consideration of the ubiquity of swift particles in space environment, understanding the effects of ion irradiation on the adhesion force and mechanical properties of multi-walled carbon nanotube arrays is significant to apply the arrays as adhesive materials in space in the future. In this study, multi-walled carbon nanotube arrays prepared through chemical vapor deposition were irradiated by He2+ under different fluences and then characterized via multiple methods. The arrays were severely damaged when the fluence reached or exceeded 1 × 1016 cm−2. As the fluence increased, more amorphous carbons were generated from their original position in the carbon nanotubes. The adhesion force quickly decreased when the irradiation fluence rapidly increased, which limited the service life of the arrays as adhesive materials. Finally, the instantaneous modulus of the multi-walled carbon nanotube arrays initially increased and then decreased when the fluence increased because of the different contact modes between the indenter and the samples.Download high-res image (324KB)Download full-size image

CsPbBr3 quantum dots (QDs) were synthesized with toluene and n-hexane as solvent by hot-injection method. Radioluminescence spectra of CsPbBr3 QDs were characterized under different solvents, concentrations, and X-ray irradiation environments. The RL accounted for more than 18.1% of the total fluorescence of CsPbBr3 QDs with toluene (10 mg/ml). The CsPbBr3 QDs with n-hexane only showed RL under X-ray irradiation. Significant linear relationship was found between the RL relative intensity and tube current and solution concentration of CsPbBr3 QDs. Thus, CsPbBr3 QDs is promising scintillator material for X-ray scintillator detection and radioluminescent nuclear batteries.

•Metal–graphene nanocomposites are expected to have excellent radiation resistance.•Graphene layers can greatly affect the performance of the composites.•The effect reflected in reducing the scale of thermal spike induced by cascades.•Three mechanisms (the intercept, recoil, and energy dissipation) can explain it.•These mechanisms may provide a pathway to prevent material degradation.Metal–graphene nanocomposites are expected to have excellent radiation resistance. The intrinsic role of the graphene layers (GrLs) in their performance has not been fully understood. Five copper–graphene nanocomposite (CGNC) systems were used to investigate the detailed mechanisms underpinning this behaviour by atomistic simulation. Results showed that GrLs can reduce the formation, growth, and intensity of the thermal spike of CGNC; this effect became more evident with the increasing number of layers of graphene. The role of the GrLs can be explained by three mechanisms: first, the ultra-strength C–C bonds of graphene hindered the penetration of high-energy atoms, second, the number of recoiled atoms decreased with the increasing number of layers of graphene, and third, the energy dissipation along the graphene planes also indirectly weakened the damage caused to the entire system. These mechanisms may provide a pathway to prevent material degradation in extreme radiation environments.Download high-res image (735KB)Download full-size image

•A micro-radial radioisotope thermoelectric generator is manufactured and tested.•The simulated performance of the RTG are compared with the experimental value.•Performance characteristics were determined in different sizes and numbers.•The designed RTG is expected to be a reliable space power supply for MEMS.To satisfy the flexible power demand of the low power dissipation devices in the independent space electric system, a micro-radial milliwatt-power radioisotope thermoelectric generator (RTG) was prepared and optimized in this research. The overall geometrical dimension of the RTG in the experiment was 65 mm (diameter) × 40 mm (height). The RTG, which was built and tested using simulated radioisotope source, eventually obtained an open-circuit voltage of 92.72 mV, an electric power of 149.0 μW, and an energy conversion efficiency of 0.015% at the ambient temperature of 293.15 K and heat source power from 0.1 W to 1 W. On the basis of the structure used in the experiment, the length and cross-sectional area of the thermoelectric leg and the number of thermoelectric modules were effectively optimized through the COMSOL Multiphysics. With the optimized length of 35 mm and cross-sectional area of 1.2 mm2, the RTG with four thermoelectric modules achieved a 15.8 mW output power under 1 W heat source power. The maximum conversion efficiency calculated using COMSOL code increased to 1.58%. According to the optimized electrical output, the micro-radial RTG is expected to be a reliable space power supply for micro components and could satisfy the low power requirements of space missions.

•A new gamma/GaAs multi-level structure radiovoltaic microbattery is proposed.•The properties of the new GaAs/YSO radiovoltaic cell was discussed.•The cell with Y2SiO5 crystal can provide higher power and current output.•The irradiation resistance of Y2SiO5 crystal under X-ray excitation was studied.The design of a new gamma/GaAs multi-level structure radiovoltaic microbattery enhanced by an Y2SiO5 (YSO) crystal is proposed. By introducing the YSO crystal in the GaAs radiovoltaic cell, the output power from the cell was significantly improved. We focus on the enhancement mechanisms of performance output in one level of a multi-level structure. The radioluminescence spectra of the YSO crystal revealed its fluorescence in the wavelength range of approximately 300–700 nm. Light at the exact wavelength would normally be totally absorbed by the GaAs photovoltaic material. The radiovoltaic cells were tested using an X-ray tube to simulate the gamma rays emitted by a gamma-radioactive source. Experimental investigation showed that the YSO crystal can increase the cell output power. The output power of the new GaAs/YSO radiovoltaic cell was enhanced by more than four times compared to that of the conventional GaAs radiovoltaic cell. In addition, considering the importance of the YSO crystal in the new GaAs/YSO radiovoltaic cell, the irradiation resistance of the YSO crystal under X-ray excitation was also analysed.

•The new honeycomb and foam structures combined with a magnetic field are proposed to shield against spatial high-energy electrons.•The influences of magnetic flux density and hollow cube size on shielding property are studied.•The foam structure exhibits better shielding performance than the honeycomb structure.Shielding against spatial high-energy electron radiation is essential to the success of space exploration. Honeycomb and foam systems, combined with a magnetic field, were proposed to shield against spatial high-energy electrons given the immense mass and large amount of secondary X-rays of a passive shield and the demand for a high-intensity magnetic field of an active method. The shielding capabilities of several structures were investigated using the Monte Carlo method. The influences of magnetic flux density and hollow cube size on shielding property were studied by simulating energy deposition in a Chinese male reference phantom. Results showed that the honeycomb and foam systems enhanced the shielding capability against high-energy electrons and reduced the penetration of secondary X-rays. The effective dose in the male phantom decreased with increasing magnetic flux density. The proposed structures exhibited excellent shielding capabilities with a small hollow cube. In addition, the foam structure performed better than the honeycomb structure. Thus, the presented systems may be used for space radiation protection in a high-energy electron environment.

Cr/W multilayer nanocomposites were presented in the paper as potential candidate materials for the plasma facing components in fusion reactors. We used neutron reflectometry to measure the depth profile of helium in the multienergy He ions irradiated [Cr/W (50 nm)]3 multilayers. Results showed that He-rich layers with low neutron scattering potential energy form at the Cr/W interfaces, which is in great agreement with previous modeling results of other multilayers. This phenomenon provided a strong evidence for the He trapping effects of Cr/W interfaces and implied the possibility of using the Cr/W multilayer nanocomposites as great He-tolerant plasma facing materials.Keywords: Cr/W multilayer; He ion irradiation; interfaces; neutron reflectometry; trapping behavior

We investigated the radiation damage resistance of the Fe/Ni multilayer nanocomposites by molecular dynamics. In the paper, two types of interface configuration with different orientation relationship were constructed. Their morphology evolution and number of final surviving defects induced by cascade collisions were discussed respectively. The interfaces of the two types of Fe/Ni multilayers kept distinct during the long-time relaxation before cascade. The comparison of surviving defects number produced by PKA with 5 keV at 100 K showed that the Fe/Ni multilayers have greater radiation tolerance than that of the bulk materials. However, the orientation relationship of the interface influences the defects self-healing capability greatly when the multilayers are irradiated by higher energy PKA or at high temperature. The radiation damage resistance of the Nishiyama – Wassermann type Fe/Ni multilayers which have larger lattice misfit is more stable than that of the Kurdjumov – Sachs type.

•Various incident sites of CNTs are classified into three types for the first time.•Different ion energies and fluences are considered to study the radiation damage.•CNTs have ability to heal the radiation-induced damage at higher temperature.•Stability of a large-diameter tube excels in a slim one under the same conditions.The radiation damage and microstructure evolution of different zigzag single-walled carbon nanotubes (SWCNTs) were investigated under incident carbon ion by molecular dynamics (MD) simulations. The radiation damage of SWCNTs under incident carbon ion with energy ranging from 25 eV to 1 keV at 300 K showed many differences at different incident sites, and the defect production increased to the maximum value with the increase in incident ion energy, and slightly decreased but stayed fairly stable within the majority of the energy range. The maximum damage of SWCNTs appeared when the incident ion energy reached 200 eV and the level of damage was directly proportional to incident ion fluence. The radiation damage was also studied at 100 K and 700 K and the defect production decreased distinctly with rising temperature because radiation-induced defects would anneal and recombine by saturating dangling bonds and reconstructing carbon network at the higher temperature. Furthermore, the stability of a large-diameter tube surpassed that of a thin one under the same radiation environments.

Flexible flame-retardant composites were prepared using high-functional methyl vinyl silicone rubber matrix with B4C, hollow beads, and zinc borate (ZB) as filler materials. As filler content increased, the tensile strength, elongation, and tear strength of the composites initially increased and then decreased. The shore hardness of the composites increased with increasing filler content with a maximum value of 30 HA. The heat insulation properties of the composites with hollow beads were higher than that of the ordinary composites with the same filler mass fraction. When ZB content exceeded 12 wt%, the limit of oxygen index of the composites was higher than 27.1%. With Am–Be neutron as the test radiation source, the transmission of neutron for a 2 cm sample was only 47.8%. Powder surface modification improved the mechanical properties, thermal conductivity, flame retardancy, and neutron shielding performance of the composites, but did not affect shore hardness.

Cerenkov luminescence imaging (CLI) is a relatively new optical molecular imaging technique. The nature of Stokes shift in quantum dots (QD) can be used to improve the quality of CLI. However, the interaction mechanism of QD with Cerenkov light remains unclear. In this work, the interaction mechanism between QD and radionuclides emitting β rays, γ rays, and Cerenkov light was investigated. The 96-well plates were used to test the different levels of radioactivity of radionuclides with different QD concentrations. Transparent vials were used to determine the relationship between QD fluorescence intensity and the distance from QD to the radionuclide. In addition, black paper was used to block the transmission of Cerenkov light through the QD vials. A linear relationship was found between the number of photons and the radioactivity of radionuclides when the QD concentration was kept constant. Similarly, the number of photons was linearly related to the QD concentration when the radioactivity of radionuclides was kept constant. Furthermore, with the increases in the distance between radionuclides and quantum dots, the number of photons was exponentially decreased. Meanwhile, the number of photons emitted from QD excited by Cerenkov light accounted for 20% the total number of photons excited by 131I radionuclide. The result proved that QD was not only excited by Cerenkov light but also by other rays.

Maintaining the safety and reliability of nuclear engineering materials under a neutron irradiation environment is significant. Atomic-scale simulations are conducted to investigate the mechanism of irradiation-induced vacancy formation in CLAM, F82H and α-Fe with different neutron energies and objective laws of the effect of vacancy concentration on mechanical properties of α-Fe. Damage of these typical metal engineering materials caused by neutrons is mainly displacement damage, while the displacement damage rate and the non-ionizing effect of neutrons decrease with the increase of neutron energy. The elastic modulus, yield strength, and ultimate strength of α-Fe are in the order of magnitude of GPa. However, the elastic modulus is not constant but decreases with the increase of strain at the elastic deformation stage. The ultimate strength reaches its maximum value when vacancy concentration in α-Fe is 0.2%. On this basis, decreasing or increasing the number of vacancies reduces the ultimate strength.

Metallic multilayer nanocomposites are known to have excellent interface self-healing performance when it comes to repairing irradiation damages, thus showing promise as structural materials for advanced nuclear power systems. The present study investigated the neutron irradiation displacement damage rate, spectra of the primary knocked-on atoms (PKAs) produced in the cascade collision, and the H/He ratio in four kinds of metallic multilayer nanocomposites (Cu/Nb, Ag/V, Fe/W, and Ti/Ta) versus neutrons’ energy. Results suggest that the three neutron induced damage effects in all multilayer systems increased with the increasing of incident neutrons’ energy. For fission reactor environment (1 MeV), multilayer’s displacement damage rate is 5–10 × 1022 dpa/(n/cm2) and the mean PKAs energy is about 16 keV, without any noteworthy H/He produced. Fe/W multilayer seems very suitable among these four systems. For fusion reactor environment (14 MeV), the dominant damage effect varies in different multilayer systems. Fe/W multilayer has the lowest displacement damage under the same neutron flux but its gaseous transmutation production is the highest. Considering the displacement damage and transmutation, the irradiation resistance of Ag/V and Ti/Ta systems seems much greater than those of the other two.

•Four types of betavoltaic microbatteries were fabricated.•Output performance was measured and calculated at temperature of 213.15–333.15 K.•Temperature effect on the different microbatteries was discussed.•Radioactive sources and energy conversion devices influence the temperature effect.The effect of temperature on the output performance of four different types of betavoltaic microbatteries was investigated experimental and theoretical. Si and GaAs were selected as the energy conversion devices in four types of betavoltaic microbatteries, and 63Ni and 147Pm were used as beta sources. Current density–voltage curves were determined at a temperature range of 213.15–333.15 K. A simplified method was used to calculate the theoretical parameters of the betavoltaic microbatteries considering the energy loss of beta particles for self-absorption of radioactive source, the electron backscatter effect of different types of semiconductor materials, and the absorption of dead layer. Both the experimental and theoretical results show that the short-circuit current density increases slightly and the open-circuit voltage (VOC) decreases evidently with the increase in temperature. Different combinations of energy conversion devices and beta sources cause different effects of temperature on the microbatteries. In the approximately linear range, the VOC sensitivities caused by temperature for 63Ni–Si, 63Ni–GaAs, 147Pm–Si, and 147Pm–GaAs betavoltaic microbatteries were −2.57, −5.30, −2.53, and −4.90 mV/K respectively. Both theoretical and experimental energy conversion efficiency decreased evidently with the increase in temperature.

Employing 63Ni and 147Pm with different thicknesses and apparent activity densities, we calculated the total efficiency (ηtotal) and conversion efficiency (η) limits of betavoltaics by MCNP5 and Schottky equation. The apparent activity density, emitted average energy, and η limit increase and then reach their saturation levels with increasing source thickness. The increment rate of η limit increasingly smaller as the bandgap increases. Wide bandgap semiconductors lead η to reach saturation and ηtotal to reach maximum more quickly than narrow ones. The limit of η for 147Pm is higher than that for 63Ni. Measurement results demonstrate that high apparent activity density can improve η as expected. This study can serve as a reference to evaluate the performance of betavoltaics.

The effects of irradiation on the structural stability and magnetic properties of Fe/Ni multilayers, which are promising candidate magnet materials in fusion reactors, were investigated. Three types of Fe/Ni multilayers with different modulation periods ranging from 2 nm to 10 nm were deposited on Si (1 0 0) substrate through direct current magnetron sputtering. The multilayered samples were irradiated by 300 keV Fe10+ ions in a wide fluence range of 1.7 × 1018/m2 to 2 × 1019/m2. Magnetic hysteresis loops of pre- and post-irradiation samples were obtained using a vibrating sample magnetometer, and structural stability were analyzed by X-ray diffraction. Magnetic measurements showed that the coercive force of Fe/Ni multilayers remained stable with increasing irradiation fluence. However, saturation magnetization increased with increasing irradiation fluence. The samples with 5 nm modulation period were the least affected by irradiation among the three types of Fe/Ni multilayers. The effects of temperature during irradiation were also discussed to explore the optimum temperature of multilayers.

This paper presents the construction of Chinese hybrid radiation adult phantoms, which are compatible with anatomical parameters for the Chinese reference population. The phantoms were designed using polygonal mesh surface, which makes the phantom more flexible and realistic than previous generations. Voxelization of hybrid phantoms was performed to adopt Monte Carlo methods. External dose coefficients were calculated by Geant4 and compared to the ICRP reference phantom. The results show that the organ dose is different from ICRP116 with the low energy photons, which can be ascribed to the anatomy and topology difference of each organ. The effective dose of CHRAP is 19% higher than ICRP 116 in the energy range from 10 to 100 keV and is almost the same in the energy range from 100 keV to 10 MeV. These phantoms can be used as the basic phantom to adjust the posture or organ volume to estimate dosimetry in medical and space explorations.

•We present and test the electrical properties of the nuclear battery.•The best thickness range for ZnS:Cu phosphor layer is 12–14 mg cm−2 for 147Pm radioisotope.•The best thickness range for Y2O2S:Eu phosphor layer is 17–21 mg cm−2147Pm radioisotope.•The battery with ZnS:Cu phosphor layer can provide higher energy conversion efficiency.•The mechanism affecting the nuclear battery output performance is revealed.A radioluminescent nuclear battery based on the beta radioluminescence of phosphors is presented, and which consists of 147Pm radioisotope, phosphor layers, and GaAs photovoltaic cell. ZnS:Cu and Y2O2S:Eu phosphor layers for various thickness were fabricated. To investigate the effect of phosphor layer parameters on the battery, the electrical properties were measured. Results indicate that the optimal thickness ranges for the ZnS:Cu and Y2O2S:Eu phosphor layers are 12 mg cm−2 to 14 mg cm−2 and 17 mg cm−2 to 21 mg cm−2, respectively. ZnS:Cu phosphor layer exhibits higher fluorescence efficiency compared with the Y2O2S:Eu phosphor layer. Its spectrum properly matches the spectral response of GaAs photovoltaic cell. As a result, the battery with ZnS:Cu phosphor layer indicates higher energy conversion efficiency than that with Y2O2S:Eu phosphor layer. Additionally, the mechanism of the phosphor layer parameters that influence the output performance of the battery is discussed through the Monte Carlo method and transmissivity test.

We present a computer simulation study on the influence of incident ions on the energy transferred to primary knock-on atoms (PKAs) and defects produced in the cascade collision of irons. Three types of ions (H, Fe, and Xe, which are frequently used in irradiation experiments) with an energy of 3 MeV were simulated. According to the calculation results of SRIM, the average energy transferred to PKAs by Fe ions was the highest among the three types. Then, cascade collisions induced by PKAs with different energies were simulated by the molecular dynamics method. The maximum number of defects produced during irradiation increased, and the time taken by defect number peak formation was extended with the increased energy of PKAs. The difference in radial distribution function between pre- and post-irradiation irons showed that a higher energy of PKA transferred resulted in a flatter curve. Besides, the law of defects varying in temperature was also investigated. All the researches imply that heavy ions can substitute for neutrons in irradiation experiments which is a practicable way, but the influence of conditions must be taken into account.

The design scheme of a sandwich-structure betavoltaic microbattery based on silicon using 63Ni is presented in this paper. This structure differs from a monolayer energy conversion unit. The optimization of various physical parameters and the effects of temperature on the microbattery were studied through MCNP. For the proposed optimization design, P-type silicon was used as the substrate for the betavoltaic microbattery. Based on the proposed theory, a sandwich microbattery with a shallow junction was fabricated. The temperature dependence of the device was also measured. The open-circuit voltaic (Voc) temperature dependence of the optimized sandwich betavoltaic microbattery was linear. However, the Voc of the betavoltaic microbattery with a high-resistance substrate exponentially decreased over the range of room temperature in the experiment and simulation. In addition, the sandwich betavoltaic microbattery offered higher power than the monolayer betavoltaic one. The results of this paper provide a significant technical reference for optimizing the design and studying temperature effects on betavoltaics of the same type.

•Relationship between Cerenkov photons and neutron dose in water was investigated.•Neutron dose has good correlation with Cerenkov photons between 0.01 eV and 100 eV.•Ratio of neutron dose to Cerenkov photons is energy-independent at specified case.•Cerenkov radiation also has the potential application in neutron dose measurement.To theoretically explore the feasibility of neutron dose characterized by Cerenkov photons, the relationship between Cerenkov photons and neutron dose in a water phantom was quantified using the Monte Carlo toolkit Geant4. Results showed that the ratio of the neutron dose deposited by secondary electrons above Cerenkov threshold energy to the total neutron dose is approximately a constant for monoenergetic neutrons from 0.01 eV to 100 eV. With the initial neutron beam energy from 0.01 eV to 100 eV, the number of Cerenkov photons has a good correlation with the total neutron dose along the central axis of the water phantom. The changes of neutron energy spectrum and mechanism analysis also explored at different depths. And the ratio of total neutron dose to the intensity of Cerenkov photons is independent of neutron energy for neutrons from 0.01 eV to 100 eV. These findings indicate that Cerenkov radiation also has potential in the application of neutron dose measurement in some specific fields.

In this study, fast-curing shielding materials were prepared with a two-component polyurethane matrix and a filler material of PbO through a one-step, laboratory-scale method. With an increase in the filler content, viscosity increased. However, the two components showed a small difference. Curing time decreased as the filler content increased. The minimum tack-free time of 27 s was obtained at a filler content of 70 wt%. Tensile strength and compressive strength initially increased and then decreased as the filler content increased. Even when the filler content reached 60 wt%, mechanical properties were still greater than those of the matrix. Cohesional strength decreased as the filler content increased. However, cohesional strength was still greater than 100 kPa at a filler content of 60 wt%. The γ-ray-shielding properties increased with the increase in the filler content, and composite thickness could be increased to improve the shielding performance when the energy of γ-rays was high. When the filler content was 60 wt%, the composite showed excellent comprehensive properties.

•Neutron absorption performance of the novel neutron absorbing material was improved by adding three different kinds of neutron absorbers (LiF, Sm2O3, and Gd2O3).•The percentage of the three kinds of neutron absorbers was optimised by Monte Carlo method.•Carbon fibre and polyimide were used to enhance its mechanical behaviour and thermal behaviour.•The radiation effect of the neutron absorbing material had been studied under Co-60 irradiation, and its irradiation-resistance performance was evaluated.A novel LiF, Sm2O3, Gd2O3/carbon fibre/polyimide material was designed in order to improve the neutron absorbing performance of the spent fuel storage basket in this paper. The volume fraction of three kinds of neutron absorbers (LiF, Sm2O3and Gd2O3) in polyimide was optimised by Monte Carlo method. Calculation results showed that the novel neutron-absorbing material, in which the volume ratio of LiF, Sm2O3and Gd2O3 was 1:2:13, can achieve the best absorption capacity. Based on the calculated results, the basket material was fabricated by compression moulding, and its mechanical behaviour, thermal behaviour, and irradiation resistant behaviour were evaluated, respectively. The experimental results proved that the tensile strength of the novel neutron-absorbing material was between 195 and 346 MPa and the maximum service temperature was up to 300 °C. Gamma irradiation dose was limited to 160 kGy, the bending strength of the material kept increasing from 10 to 19 MPa.