[en] In the composite cathode of solid-state Li-metal batteries (SSLMBs), the high interfacial resistance and unstable interphase between the cathode active material (CAM) and solid-state electrolyte (SSE) are two of the main reasons for the low energy density in current SSLMBs. Matching the physical/(electro)chemical properties of the CAM and SSE is vital to obtaining a stable interface/interphase in the composite cathode. Li${}_{1.3}$Al${}_{0.3}$Ti${}_{1.7}$(PO${}_4$)${}_3$ (LATP) is a promising candidate as a Li${}^{+}$ conductive component in all-phosphate-based composite cathode produced by a co-firing method due to its good thermal chemical stability against phosphate-based CAMs. Herein, with the effort to optimize the synthesizing and sintering process of LATP, highly-conductive LATP is obtained at a low sintering temperature. Consequently, the phosphate-based CAM/LATP interface in composite cathode is stabilized, which significantly improves the energy density of SSLMBs. Specifically, a high-density, fully phosphate-based composite cathode is prepared by co-firing LiFePO${}_4$ (LFP) and LATP. In this way, an ion-conductive and redox-active Li${}_{3-<!--\; ???\; -->x}$Fe${}_{2-<!--\; ???\; -->x-<!--\; ???\; -->y}$Ti${}_x$Al${}_y$(PO${}_4$)${}_3$ (LFTAP) interphase is formed at the interface between LFP and LATP after heating, which not only improves the adhesion of materials but also provides additional capacity. The structure of the fabricated composite cathode is studied in detail. The electrochemical performance and the influence of the electrochemically active LFTAP interphase on the corresponding SSLMBs composed of the co-fired LFP/LATP composite cathodes, PEO-based solid polymer electrolytes and Li metal anodes are investigated.The active interphase in co-fired LFP/LATP composite cathode enables the SSLMBs to achieve high areal capacities (2.0 ~ 3.0 mAh cm${}^{-<!--\; ???\; -->2}$). Whereas, the adoption of PEO-based SSE restricts the batteries to be operated under a low current density at a relative high temperature (eg. 36 µA cm${}^{-<!--\; ???\; -->2}$, 60 °C). To enhance the Li${}^{+}$ kinetic in SSE at room temperature (RT), single Li${}^{+}$ conducting polymer-in-ceramic free-standing hybrid electrolyte membranes are prepared for solid-state Li metal batteries. The hybrid electrolyte membrane is composed of 3D interconnected LATP ceramic and a conductive polymer matrix of cross-linked poly[bis(2-(2-methoxyethoxy)ethoxy)-phosphazene] (MEEP) and lithium(4-styrenesulfonyl)-(trifluoromethanesulfonyl)imide (LiSTFSI). Attributed to the synergistic effects of LATP nanofibers and the single-ion conducting polymer, the hybrid electrolyte exhibits improved electrochemical performance, leading to enhanced rate capability and stable cycling performance of the LFP|hybrid electrolyte|Li battery.

[en] In order to keep the GPU accelerated Monte Carlo code to be able to handle 3D geometry and continuous energy point cross section, the method of geometry treatment acceleration by GPUs was proposed. The fission neutrons were organized into a neutron vector, and the geometry part of the Monte Carlo code was transplanted to GPUs. To reduce the negative impact of data communication on the performance of the accelerated code, CUDA streams were applied to design the asynchronous parallel algorithm. Two benchmarks including the fast reactor facility and the 17 × 17 PWR assembly were used for performance test. The results are satisfying and demonstrate that the speedup factor is close to the theoretical one for the local acceleration method. (authors)

[en] Highlights: • High-throughput sequencing was used to compare sludge bacteria with and without TC. • Bacterial diversity increased with TC addition despite of various oxygen conditions. • Total TRGs proliferated with TC addition in three kinds of sludge. • The concentration of efflux pump genes was the highest in the three groups of TRGs. - Abstract: Two lab-scale anaerobic-anoxic-oxic (AAO) systems were used to investigate the changes in tetracycline (TC) resistance and bacterial diversity upon exposure to TC pressure. High-throughput sequencing was used to detect diversity changes in microorganisms at the level of class in sludge from different bioreactors with and without TC. Real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) was used to detect the abundances of eight tetracycline resistance genes (TRGs), tetA, tetB, tetC, tetE, tetM, tetO, tetS and tetX. The results showed that the diversities of the microbial communities of anoxic, anaerobic and aerobic sludge all increased with the addition of TC. TC substantially changed the structure of the microbial community regardless of oxygen conditions. Bacteroidetes and Proteobacteria were the dominant species in the three kinds of sludge and were substantially enriched with TC pressure. In sludge with TC added, almost all target TRGs proliferated more than those in sludge without TC except tetX, which decreased in anaerobic sludge with TC addition. The concentration of efflux pump genes, tet(A–C, E), was the highest among the three groups of TRGs in the different kinds of sludge

[en] During the early period of a supercritical system, the growth of fission chains shows a significant stochastic feature. In multiplying medium, it is a probability issue of fail-pass type for a single neutron to sponsor a divergent fission chain, and the probability of success is named as single neutron initiation probability. Meanwhile, in the presence of a weak neutron source, the time at which fission burst occurs also exhibits a stochastic nature, which can be observed on experiments of pulsed reactors such as GODIVA I and GODIVA II. The initiation probability and burst waiting time reflect the dynamic feature of a supercritical system, which are very important for nuclear criticality safety concerns. It is desirable that a supercritical system has an initiation probability very close to zero and releases limited energy in case of criticality accidents. The stochastic process of neutron population evolution in early age in a multiplying system is governed by Bell's equation in the form of an adjoint neutron transport equation with a non-linear fission term. In order to solve this stochastic neutron transport equation, the deterministic method discretizing the phase space was proposed long ago and has been implemented in several SN codes such as Partisn, Ardra and PANDA. However, the deterministic method is of limited usage, due to its poor ability to precisely describe real-world 3D complex geometries and continuous energy neutron spectrum. Recently, Monte Carlo methods have gradually gained attention for solving Bell's equation. Greenman from LLNL proposed an analog Monte Carlo forward-transport method for calculating initiation probability in 2007. He implemented this method by introducing the maximum age parameter, the time sub-interval and the neutron progenitor tag into Mercury in time-dependent fixed-source simulation mode. This method is only suitable for initiation probability calculations, however not for analyzing the randomness of burst waiting time. Later, GANG in 2011 developed the GSMP (Generalized Semi-Markov Process method) Monte Carlo method according to Bell's equation. While the GSMP method, which can deal with both initiation probability and burst waiting time, is flexible and powerful for zero-dimensional problems, it is not favorable when extended to 3D and continuous energy problems due to severe lack of computational efficiency. In 2015, a direct Monte Carlo simulation method for stochastic systems problems was implemented in MCATK, yet this method has not been applied specifically to the burst waiting time. In this work, a new and efficient 3D Monte Carlo direct simulation method for calculating both the initiation probability and the burst waiting time is developed. By taking random factors during evolvement of fission chains into account in dynamic Monte Carlo simulation, this new method has the potential of simulating the whole process from source neutron injection to exponential growth of the neutron population, and finally to extinction of the neutron pulse. This capability is useful in criticality accidents evaluation and pulsed reactor experiments explanation. (authors)

[en] '111' products have been trial produced by a sandstone type uranium deposit in Inner Mongolia. There is a large amount of visible water in it, and the quality of the product is not qualified. In view of this situation, the precipitation process optimization experiment was carried out. Test results show that, the precipitation process of acidification tank precipitation and sedimentation tank aging precipitation is adopted, the product has no visible water, basically conforms to the qualified product standard. The optimized process saves reagent consumption and power use greatly, and further reduces the production cost. (authors)

[en] In this paper, the adaptability of the neutron diffusion numerical algorithm on GPUs was studied, and a GPU-accelerated multi-group 3D neutron diffusion code based on finite difference method was developed. The IAEA 3D PWR benchmark problem was calculated in the numerical test. The results demonstrate both high efficiency and adequate accuracy of the GPU implementation for neutron diffusion equation. (authors)

[en] In the expanding tests of the ion exchange resin adsorption, there are precipitations which lead to the blocking of resin beds. The stemming are mainly carbonate sediments and fine sediment particles. Replacing the smaller aperture of mesh to prevent the sediment into the tower, and adding CO₂ in front of the tower instead of the behind can fundamentally solve the problem of the resin harden, for it can adjust the pH value of the raw liquor and then prevent the formation of carbonate sediments. (authors)

[en] It is necessary to know the contribution of each assembly when the in-core flux distribution based on the response of the ex-core detector is studied. A new method to study the contribution of each part in core to ex-core detector was introduced in this paper. The producing and reacting position of neutron in simulation neutron transportation was documented through writing Monte Carlo code, the distribution of the source of neutron received by detector in the process of simulating detector response was recorded, and the contribution of each part in core to detector was gained. The research result shows that neutron received by detector is mainly from three assemblies. The flux of these three assemblies has the greatest influence on ex-core detector counting. The contributions of outmost assembly, second assembly and third assembly are about 77%, 20% and 3%, respectively. Flux distribution has little effect on this result and it demonstrates that the spatial effect has an important influence on contribution of the detector. (authors)

[en] With large time steps, improved quasi-static (IQS) method can improve the calculation speed for reactor dynamic simulations. The Monte Carlo IQS method was proposed in this paper, combining the advantages of both the IQS method and MC method. Thus, the Monte Carlo IQS method is beneficial for solving space-time dynamics problems of new concept reactors. Based on the theory of IQS, Monte Carlo algorithms for calculating adjoint neutron flux, reactor kinetic parameters and shape function were designed and realized. A simple Monte Carlo IQS code and a corresponding diffusion IQS code were developed, which were used for verification of the Monte Carlo IQS method. (authors)

[en] This paper presents the burnup calculation capability of RMC, which is a new Monte Carlo (MC) neutron transport code developed by Reactor Engineering Analysis Laboratory (REAL) in Tsinghua University of China. Unlike most of existing MC depletion codes which explicitly couple the depletion module, RMC incorporates ORIGEN 2.1 in an implicit way. Different burn step strategies, including middle-of-step approximation and predictor-corrector method, are adopted by RMC to assure accuracy under large step size. RMC employs a spectrum-based method of tallying one-group cross section, which can considerably save computational time with negligible accuracy loss. According to validation results of benchmarks and examples, it is proved that the burnup function of RMC performs quite well in accuracy and efficiency. (author)