Vol.32,

High-temperature chromium (Cr)-zirconium (Zr) interdiffusion commonly occurs in Cr-coated zircaloys applied for enhanced accident-tolerant fuel (ATF) claddings. Such interdiffusion changes the interfacial microstructure and thus the fracture mechanism of the coating under external loading. In this study, the interdiffusion behavior in a magnetron sputtered Cr coating deposited on a Zr-4 alloy was studied in a vacuum environment at 1160 °C. In addition, the effect of interdiffusion on the microcracking behavior of the Cr coating was determined by in situ three-point bending tests. The experimental results show that the interdiffusion behavior resulted in the formation of a ZrCr₂ layer, accompanied by the consumption of Cr coating and interfacial roughening. The growth of the diffusion layer followed a nearly parabolic law with respect to annealing time, and the residual stress of the annealed coating decreased with increasing annealing time. Under external loading, a large number of cracks were generated in the brittle interlayer, and some interfacial cracks were formed and grew at the ZrCr₂/Zr-4 interface. Despite the remarkable microcracks in the ZrCr₂ layer, the vacuum-annealed Cr coating has significantly fewer cracks than the original coating, mainly because of the recrystallization of the coating during annealing.

489

Herein, we report a facile solution process for preparing multi-walled carbon nanotube (MWCNT) bucky paper for solar-driven interfacial water evaporation. This process involves vacuum filtrating a dispersion of MWCNTs that was modified by polyvinyl alcohol (PVA) under γ-ray irradiation on a cellulose acetate microporous membrane, followed by borate crosslinking. Fourier transform infrared spectroscopy, Raman spectroscopy, and thermogravimetry confirmed the success of PVA grafting onto MWCNTs and borate crosslinking between modified MWCNT nanoyarns. The as-prepared crosslinked MWCNT bucky papers (BBP membranes) were used as a solar absorber, by placing them on a paper-wrapped floating platform, for interfacial water evaporation under simulated solar irradiation. The BBP membranes showed good water tolerance and mechanical stability, with an evaporation rate of 0.79 kg m^-2 h^-1 and an evaporation efficiency of 56% under 1 sun illumination in deionized water. Additionally, the BBP membranes achieved an evaporation rate of 0.76 kg m^-2 h^-1 in both NaCl solution (3.5 wt%) and sulfuric acid solution (1 mol L^-1), demonstrating their impressive applicability for water reclamation from brine and acidic conditions. An evaporation rate of 0.70 kg m^-2 h^-1 (very close to that from deionized water) was obtained from the solar evaporation of saturated NaCl solution, and the BBP membrane exhibited unexpected stability without the inference of salt accumulation on the membrane surface during long-term continuous solar evaporation.

325

In this study, pure Ni was demonstrated to protect the GH3535 alloy from Te vapor corrosion because of its strong absorption capacity. Severe Te corrosion of a single GH3535 alloy sample occurred in Te vapor at 700 °C, which manifested as complex surface corrosion products and deep intergranular cracks. However, when pure Ni and the GH3535 alloy were put together in the vessel, the GH3535 alloy was completely protected from Te corrosion at the expense of the pure Ni. Thermodynamic calculations proved that the preferential reaction between pure Ni and Te vapor reduced the activity of Te vapor considerably, preventing the corrosion of the GH3535 alloy. Our study reveals one potential approach for protecting the alloys used in molten-salt reactors from Te corrosion.

308

The High Energy Photon Source (HEPS) is a 6 GeV diffraction-limited storage ring light source under construction. The swap-out injection is adopted with the depleted bunch recycled via high-energy accumulation in the booster. The extremely high beam energy density of the bunches with an ultra-low emittance (about 30 pm horizontally and 3 pm vertically) and high bunch charges (from 1.33 nC up to 14.4 nC) extracted from the storage ring could cause hazardous damage to the extraction Lambertson magnet in case of extraction kicker failure. To this end, we proposed the use of a pre-kicker to spoil the bunches prior to extraction, significantly reducing the maximum beam energy density down to within a safe region while still maintaining highly efficient extractions. The main parameters of the pre-kicker are simulated and discussed.

643

The possibility of utilizing thorium as a fuel in a pressurized water reactor (PWR) has been proven from the neutronic perspective in our previously published work without assessing the thermal-hydraulic (TH) and solid structure performances. Therefore, the TH and solid structure performances must be studied to confirm these results and ensure the possibility of using a thorium-based fuel as an excellent accident-tolerant fuel. The TH and solid structure performances of thorium-based fuels were investigated and compared with those of UO₂. The radial and axial power peaking factors (PPFs) for UO₂, (²³²Th,²³⁵U) O₂, and (²³²Th,²³³U) O₂ were examined with a PWR assembly to determine the total PPF of each one. Both Gd₂O₃ and Er₂O₃ were tested as burnable absorbers (BAs) to manage the excess reactivity at the beginning of the fuel cycle (BOC) and reduce the total PPF. Er₂O₃ resulted in a more significant reduction to the total PPF and, therefore, a greater reduction to the temperature distribution compared to Gd₂O₃. Given these results, we analyzed the effects of adding Er₂O₃ to thorium-based fuels on their TH and solid structure performances.

452

Lithium heat pipes have broad applications in heat pipe cooling reactors and hypersonic vehicles owing to their ultra-high working temperature. In particular, when the length of the lithium heat pipe is ultra-long, the flow and heat transfer characteristics are more complex. In this study, an improved lumped parameter model that considers the Marangoni effect, bending effect, and different vapor flow patterns and Mach numbers was developed. Thereafter, the proposed model was verified using the University of New Mexico’s Heat Pipe (UNM-HP) and HTPIPE models. Finally, the verified model was applied to simulate the steady-state operation of an ultra-long lithium heat pipe in a Heat Pipe-Segmented Thermoelectric Module Converters (HP-STMC) space reactor. Based on the results: (1) Vapor thermal resistance was dominant at low heating power, and decreased with increasing heating power. The vapor flow inside the heat pipe developed from the laminar to the turbulent phase, whereas the liquid phase in the heat pipe was always laminar. (2) The vapor pressure drop caused by bending was approximately 22%–23% of the total, and the bending effect on the liquid pressure drop could be ignored. (3) The Marangoni effect reduced the capillary limit by hindering the liquid reflux, especially at low vapor temperatures. Without considering the Marangoni effect, the capillary limit of the lithium heat pipe was overestimated by 30% when the vapor temperature was 1400 K. (4) The total thermal resistance of the heat pipe significantly increased with increasing adiabatic length when the vapor temperature was low. Further, the wick dryness increased with increasing adiabatic length at any vapor temperature. Such findings improve on current knowledge for the optimal design and safety analysis of a heat pipe reactor, which adopts ultra-long lithium heat pipes.

444

A proton therapy (PT) facility with multiple treatment rooms based on the superconducting cyclotron scheme is under development at Huazhong University of Science and Technology (HUST). This paper attempts to describe the design considerations and implementation of the PT beamline from a systematic viewpoint. Design considerations covering beam optics and the influence of high-order aberrations, beam energy/intensity modulation, and beam orbit correction are described. In addition to the technical implementation of the main beamline components and subsystems, including the energy degrader, fast kicker, beamline magnets, beam diagnostic system, and beamline control system are introduced.

475

A dual double interlocked storage cell (DICE) interleaving layout static random-access memory (SRAM) is designed and manufactured based on 65 nm bulk complementary metal oxide semiconductor (CMOS) technology. The single event upset (SEU) cross-sections of this memory are obtained via heavy ion irradiation with a linear energy transfer (LET) value ranging from 1.7 to 83.4 MeV/(mg/cm²). Experimental results show that the upset threshold (LET_th) of a 4 KB block is approximately 6 MeV/(mg/cm²), which is much better than that of a standard unhardened SRAM with an identical technology node. A 1 KB block has a higher LET_th of 25 MeV/(mg/cm²) owing to the use of the error detection and correction (EDAC) code. For a Ta ion irradiation test with the highest LET value (83.4 MeV/(mg/cm²)), the benefit of the EDAC code is reduced significantly because the multi-bit upset proportion in the SEU is increased remarkably. Compared with normal incident ions, the memory exhibits a higher SEU sensitivity in the tilt angle irradiation test. Moreover, the SEU cross-section indicates a significant dependence on the data pattern. When comprehensively considering HSPICE simulation results and the sensitive area distributions of the DICE cell, it is shown that the data pattern dependence is primarily associated with the arrangement of sensitive transistor pairs in the layout. Finally, some suggestions are provided to further improve the radiation resistance of the memory. By implementing a particular design at the layout level, the SEU tolerance of the memory is improved significantly at a low area cost. Therefore, the designed 65 nm SRAM is suitable for electronic systems operating in serious radiation environments.

379

The rapid identification of radioactive substances in public areas is crucial. However, traditional nuclide identification methods only consider information regarding the full energy peaks of the gamma-ray spectrum and require long recording times, which lead to long response times. In this paper, a novel identification method using the event mode sequence (EMS) information of target radionuclides is proposed. The EMS of a target radionuclide and natural background radiation were established as two different probabilistic models and a decision function based on Bayesian inference and sequential testing was constructed. The proposed detection scheme individually processes each photon. When a photon is detected and accepted, the corresponding posterior probability distribution parameters are estimated using Bayesian inference and the decision function is updated. Then, value of the decision function is compared to preset detection thresholds to obtain a detection result. Experiments on different target radionuclides (¹³⁷Cs and ⁶⁰Co) were performed. The count rates of the regions of interest (ROI) in the backgrounds between [651, 671], [1154, 1186], and [1310, 1350] keV were 5.05, 3.83, and 3.61 CPS, respectively. The experimental results demonstrate that the proposed method can identify ¹³⁷Cs in 3.8 s with a full energy peak count rate of 5.05 s⁻¹ and can identify ⁶⁰Co in 4.1 s with a full energy peak count rate of 7.44 s⁻¹. The results demonstrate that the proposed method can detect radioactive substances with low activity.

583

In experiments searching for rare signals, background events from the detector itself are some of the major factors limiting search sensitivity. Screening for ultra-low radioactive detector materials is becoming ever more essential. We propose to develop a gaseous time projection chamber (TPC) with a Micromegas readout for radio screening. The TPC records three-dimensional trajectories of charged particles emitted from a flat sample placed in the active volume of the detector. The detector can distinguish the origin of an event and identify the particle types with information from trajectories, which significantly increases the screening sensitivity. For α particles from the sample surface, we observe that our proposed detector can reach a sensitivity higher than 100 μBq⋅m^-2 within two days.

377