Vol.37,

Fuel-coolant interaction (FCI) remains one of the most complex challenges in severe accident research, with the triggering process being a key aspect that may govern subsequent fine fragmentation and potential steam explosions. In this study, the evolution characteristics of droplet-water interactions under external disturbance conditions were investigated using a self-designed FCI experimental setup. The experimental observations revealed that cavity formation reduced the drag force on the droplet, thereby increasing its peak velocity. However, the external disturbance pressure can disrupt the cavity, leading to a reduction in the droplet peak velocity. Furthermore, it was found that an increase in external disturbance pressure tended to increase the peak value of the droplet expansion rate, thereby promoting the fine-fragmentation process. This effect holds regardless of the initial droplet temperature, coolant temperature, or even when using droplet materials such as lead, which is generally considered unfavorable for steam explosions. Comparative analyses indicated that a higher external disturbance pressure may shorten the triggering time of the droplet surface and enhance the trigger intensity. These findings provide important phenomenological insights for further investigation of the triggering mechanisms in the initial stage of fuel-coolant interactions.

One of the main issues in designing optimum tapered cascades for uranium enrichment for annual fuel production in a power reactor is whether to employ large (fat) or small (thin) cascades. What will be the permissible and optimal ranges of the number of machines that can be used in a cascade? For the first time, the permissible and optimal ranges of the number of gas centrifuges that can be utilized in a cascade were investigated using two types of centrifuges, and the performance of small and large tapered cascades was discussed. The particle swarm optimization algorithm (PSO) has been used to optimize tapered cascades. The results show: (1) For the first centrifuge, 41 cascades (91≤n≤4897) and for the second centrifuge, 49 cascades (18≤n≤3839) with small and large sizes can be used in enrichment facilities, and the best cascade for them has 530 (with 23 stages) and 39 (with 7 stages) centrifuges, respectively. (2) For both centrifuges, when 600 ≤ n (number of centrifuges = n), the large cascade performance changes are relatively insignificant. (3) For both types of gas centrifuges, the annual loss of separation power in enrichment facilities is approximately 1.25–4.82% of the total separation work required.

The ultracold neutron (UCN) transport code, MCUCN, designed initially for simulating UCN transportation from a solid deuterium (SD₂) source and neutron electric dipole moment experiments, could not simulate UCN storage and transportation in a superfluid ⁴He (SFHe, He-II) source accurately. This limitation arose from the absence of an ⁴He upscattering mechanism and the absorption of ³He. And the provided source energy distribution in MCUCN is different from that in SFHe source. This study introduced enhancements to MCUCN to address these constraints, explicitly incorporating the ⁴He upscattering effect, the absorption of ³He, the loss caused by impurities on converter wall, UCN source energy distribution in SFHe, and the transmission through negative optical potential. Additionally, a Python-based visualization code for intermediate states and results was developed. To validate these enhancements, we systematically compared the simulation results of the Lujan Center Mark3 UCN system by MCUCN and the improved MCUCN code (iMCUCN) with UCNtransport simulations. Additionally, we compared the results of the SUN1 system simulated by MCUCN and iMCUCN with measurement results. The study demonstrates that iMCUCN effectively simulates the storage and transportation of ultracold neutrons in He-II.

The evaporation residual cross sections (ERCSs) of these reactions were calculated by using ¹⁴⁴Sm, ^160,164Dy, ¹⁶⁵Ho, ¹⁶⁶Er, ¹⁶⁹Tm, ^171,174Yb, ¹⁷⁵Lu, ^176-180Hf, ¹⁸¹Ta, ^180,182W and ¹⁸⁷Re targets with ⁴⁰Ar projectiles in the theoretical framework of the dinuclear system (DNS) model. The de-excitation process of the compound nucleus was theoretically calculated using two different statistical models, namely the statistical model 1 and statistical model 2 (GEMINI++ model). The calculated ERCSs were also compared with the experimental data. The ERCSs of synthesizing new proton-rich nuclides were investigated based on the fusion evaporation reaction. Predictions were made for the ERCSs of new isotopes of Pu, Cm and Bk in the heavy nuclei region, while the new isotopes of Ds, Cn and Fl are predicted in the superheavy nuclei region of Z≥104.

Research on neutron-induced fission product yields of ²³²Th is crucial for understanding the competition between symmetric and asymmetric fission in actinide nuclei. However, obtaining complete isotopic yield distributions over a wide range of neutron energies remains a challenge. In this study, a Bayesian neural network (BNN) model was developed to predict the independent (IND) and cumulative (CUM) fission yields of ²³²Th under neutron irradiation at various incident energies. To address the limited availability of experimental data for the analysis of IND mass distributions, we substituted mass-number-based yields with the yields of specific isotopes. Furthermore, physical phenomena or quantities, such as the odd-even effect and isospin, were introduced as constraints to enhance the physical consistency of the predictions. The impact of these constraints was evaluated using mass-chain yield distributions and their dependence on energy. Incorporating physical constraints significantly improves the prediction accuracy, yielding more reliable and physically meaningful fission yield data for nuclear physics and reactor design applications.

The high-order deformation effects in even-even ^246,248No are investigated by means of pairing self-consistent Woods-Saxon-Strutinsky calculations using the potential-energy-surface (PES) approach in an extended deformation space (β2,β3,β4,β5,β6,β7,β8). Based on the calculated two-dimensional-projected energy maps and different potential-energy curves, we found that the highly even-order deformations have an important impact on both the fission trajectory and energy minima, while the odd-order deformations, accompanying the even-order ones, primarily affect the fission path beyond the second barrier. Relative to the light actinide nuclei, the nuclear ground state changes to the superdeformed configuration, but the normally-deformed minimum, as the low-energy shape isomer, may still be primarily responsible for enhancing nuclear stability and ensuring experimental accessibility in ^246,248No. Our present investigation indicates the nonnegligible impact of high-order deformation effects along the fission valley and will be helpful for deepening the understanding of different deformation effects and deformation couplings in nuclei, especially in this neutron-deficient heavy-mass region.

The process of nuclear fusion in the presence of a laser field was theoretically analyzed. The analysis is applicable to most fusion reactions and different types of currently available intense lasers, from X-ray free electron lasers to solid-state near-infrared lasers. Laser fields were shown to enhance the fusion yields, and the mechanism of this enhancement was explained. Low-frequency lasers are more efficient in enhancing fusion than high-frequency lasers. The calculation results show enhancements of fusion yields by orders of magnitude with currently available intense low-frequency laser fields. The temperature requirement for controlled nuclear fusion may be reduced with the aid of intense laser fields.

We investigate the effects of temperature on the structural evolution and clustering in the hypernucleus, taking Λ21Ne as an example, in the framework of deformed finite-temperature Skyrme-Hartree-Fock. The SkI4 Skyrme force is employed for nucleon-nucleon interaction, while the NSC97f force is used for the hyperon-nucleon interaction. It is found that the system exhibits a strongly deformed ground state with pronounced α-cluster correlations and localized density distributions at low temperatures. As temperature increases, nuclear deformation weakens, the nuclear density spreads over the surface, and clustering gradually diminishes and vanishes entirely at T≈2.8 MeV. This is due to that the thermal excitations lower the Fermi surface and enhance single-particle level splitting. In particular, owing to the lower excitation threshold of hyperons in the hypernuclear system, the hyperon radii exhibit a stronger temperature dependence than the nucleons. We further analyze the temperature-dependent changes in deformation, single-Λ binding energy, and entropy, providing new insights into the thermal evolution of the hypernuclear structure.

Many adsorbents have been developed for uranium recovery to ensure global energy and environmental security. However, most reported adsorbents involve complex preparation process and rely heavily on petrochemical feedstocks, which undoubtedly increases carbon emissions from production in the nuclear industry. Here, a biomass aerogel (CS-BT) is prepared by the facile cross-linking of chitosan and bayberry tannins with glutaraldehyde. U(VI) can be adsorbed by hydroxyl groups on CS-BT aerogel via chelation, and the maximum adsorption capacity of the obtained aerogel to U(VI) is 140 mg·g^-1 and the removal rate reaches up to 99% (at 298.15 K, pH = 5.0). The pseudo-second-order kinetics model and Freundlich model can better match the adsorption process of CS-BT aerogel, implying that its adsorption is a chemical adsorption process dominated by multilayer adsorption. The thermodynamic results show that the adsorption process of U(VI) by CS-BT aerogel is spontaneous and exothermic. Hence, our biomass aerogel can effectively extract uranium from water, contributing to the sustainable development of the nuclear industry.

At high count rates, pile-up events involving neutron and gamma signals result in inaccurate neutron counting and distortions in the energy spectrum. Additionally, a bipolar cusp-like pulse-shaping algorithm based on an unfolding synthesis technique was proposed. This algorithm exhibits a narrow pulse shape, and the parallel design of the dual algorithms enables the recovery of pile-up signal amplitudes while preserving the distinct characteristics of neutron and gamma signals. The simplicity of the algorithm facilitates real-time neutron/gamma discrimination on an FPGA, allowing the energy spectra to be updated with each incoming signal. Furthermore, the algorithm can be readily tailored to various experimental conditions by adjusting the decay time constants. Multi-objective optimization reduces the need for manual parameter tuning by rapidly identifying the optimal parameters. Testing with a ²⁴¹Am-Be neutron source and a NaIL scintillator yielded a Figure of Merit (FoM) value of 2.11 and produced a clear energy spectrum even at high count rates.

This paper quantitatively discusses the influence of well contact on Single Event Transient (SET) in sub-20 nm FinFET by Two-Photon Absorption (TPA) pulse laser. Two groups of inverter chains were designed to investigate the impact of well contact distance on the FinFET process. The experimental results show that the SET pulse width has a bimodal symmetric distribution, which is different from that of a bulk planar CMOS device. To investigate the detailed mechanism of the phenomenon, a high-precision FinFET TCAD model was established, in which both Id-Vd and Id-Vg errors were less than 10% compared to the SPICE model provided by the commercial process. TCAD simulation under heavy ion injection showed the mechanism of the abnormal phenomenon, where the well contact plays a major role in charge collection at the near-well contact distance, while the source plays a major role at the far distance. This phenomenon is completely different from that of planar CMOS devices. This indicates that the SET mechanism becomes more complicated during the FinFET process. Therefore, more effective SET hardening methods should be investigated for FinFET.

There is a contradiction between the evolution rate of materials and the time resolution of SR-CT characterization in the in situ synchrotron radiation computed tomography (SR-CT) characterization of ultrafast evolution process. The sampling strategy of the ultra-sparse angle is an effective method for improving time resolution. Accurate reconstruction under sparse sampling conditions has always been a bottleneck problem. In recent years, convolutional neural networks have shown outstanding advantages in sparse-angle CT reconstruction given the development of deep learning. However, existing ideas did not consider the expression of high-frequency details in neural networks, limiting their application in accurate SR-CT characterization. A novel high-frequency information constrained deep learning network (HFIC-Net) is proposed in response to this problem. Additional high-frequency information constraints are added to improve the accuracy of the reconstruction results. Further, a series of numerical reconstruction experiments are conducted to verify this new method, and the results indicate that the reconstruction results of HFIC-Net method effectively improve reconstruction quality. This new method uses only eight angle projections to achieve the reconstruction effect of the filtered back projection method (FBP) method in 360 projections. The results of the HFIC-Net method demonstrate clear boundaries and accurate detailed structures, correcting the misinformation caused by using other methods. For quantitative evaluation, the SSIM used to evaluate image structure similarity is increased from 0.1951, 0.9212, and 0.9308 for FBP, FBP-Conv, and DDC-Net, respectively, to 0.9620 for HFIC-Net. Finally, the results of actual SR-CT experimental data indicate that the new method can suppress artifacts and achieve accurate reconstruction, and it is suitable for the in situ SR-CT accurate characterization of ultrafast evolution process.

Rotational computed laminography (CL) has broad application potential in three-dimensional imaging of plate-like objects because it only requires X-rays to pass through the tested object in the thickness direction during the imaging process. In this study, a rectangular cross-section field-of-view rotational CL (RC-CL) is proposed for circuit-board imaging. Compared to other rotational CL systems, the field-of-view is the largest and most suitable for rectangular circuit boards. Meanwhile, as the imaging geometry of RC-CL is significantly different from that of cone-beam CT, the Feldkamp-Davis-Kress (FDK) reconstruction algorithm cannot be used directly. However, transferring the projection data to fit into the CBCT geometry using two-dimensional interpolation introduces interpolation errors. Therefore, an FDK-type analytical reconstruction algorithm applicable to RC-CL was developed. The effectiveness of the method was validated through numerical experiments, and the influence of the tilt angle on the reconstruction results was analyzed. Finally, the RC-CL technique was applied to real defect-detection research on circuit boards.

A solenoid is typically used in normally conducting and superconducting radio frequency (SRF) photoinjectors to compensate for the projected transverse beam emittance. In the ELBE SRF Gun-II, a superconducting solenoid is positioned inside the gun cryomodule approximately 0.7 m from the end of the gun cavity. The spherical aberration and multipole field effects caused by offset and tilt limit the reduction in beam emittance for high bunch charges. We designed a novel superconducting (SC) solenoid with a lower spherical aberration coefficient. In the simulation, the beam emittance from the spherical aberration decreased by 47%. Both the longitudinal and transverse fields were measured and analyzed using the formalism fitting method to assess the performance of the SC solenoid within the cryomodule and its influence on the beam transverse emittance.

Preserving beam quality during the transport of high-brightness electron bunches is crucial for advanced accelerator applications, such as particle colliders, free-electron lasers, and recirculating linacs. However, coherent synchrotron radiation (CSR) significantly degrades beam quality when electron bunches pass through multi-bend isochronous beamlines, particularly for short bunches with non-ideal longitudinal profiles. Although several methods have been proposed to mitigate CSR effects, most rely on small-angle approximations or are limited to idealized bunch profiles. In this study, we present two improved methods for designing isochronous triple-bend achromat (TBA) beamlines that effectively mitigate CSR-induced emittance growth and longitudinal profile distortion without relying on small-angle approximations. The first method, an enhanced integral optimization approach, simplifies numerical optimization and can accurately handle larger deflection angles, making it suitable for practical applications that require flexible lattice configurations. The second method, an optimized I-matrix approach, completely cancels steady-state and transient CSR kicks through specific matrix constraints and higher-order dispersion optimization, enabling effective CSR suppression even with very large deflection angles. Systematic simulations demonstrate that both methods achieve excellent preservation of transverse emittance and longitudinal profiles.

In response to the increasing demand for hadron therapy facilities, significant efforts have been directed toward enhancing the performance of high-gradient and high-transmission injectors for light-ion beams. For carbon ion irradiations, which offer greater radiobiological efficiency in tumor treatment, recent research has focused on developing high-production sources of fully stripped C⁶⁺ ions and highly compact, high-frequency RFQ cavities. This study explores the design possibilities of a carbon ion acceleration section using 750 MHz Interdigital H-mode Drift Tube Linacs (IH-DTLs) as a high-efficiency solution for accelerating ions in the 5–10 MeV per nucleon energy range. A particle-tracking routine based on the TRAVEL code was developed to design the acceleration line through a tailored KONUS-type configuration. Three design solutions were proposed and compared, exploring different alternatives regarding the use of a MEBT to match the output beam phase space of the RFQ to the optics of the line, as well as varying considerations for magnetic systems to focus the beam. Additionally, the compatibility of the proposed solutions with the existing design of the carbon-ion bent-linac for hadron therapy was assessed.