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The fast reactor is gradually being paid attention to in nuclear power due to a better breeding effect, and its economy is also directly followed. Due to the restriction of the core power density, the core power level is directly related to the volume of the core active area. When the power level and the volume of the core gradually increase, the mass of uranium and 235U in the core at the beginning of life will gradually increase on the basis of a critical uranium inventory. At the same time, due to the gradual increase in the breeding effect, the utilization rate of uranium resources at the end of life will gradually increase. Due to the characteristics of the large critical uranium mass and high breeding effect, the mass of uranium and 235U in the low power level core at the beginning of life cannot be further reduced because of the critical uranium inventory. The lifetime of the high power level core should be extended to use the wealthy reactivity of the core because of the improvement in the breeding effect. However, due to the requirements of the nuclear power refuel time and the limitation to fuel consumption, the breeding effect brought by the improvement in the core power level and the size of the active zone may be less effective. In this article, the power level and economy of lead-based modular nuclear power are analyzed, and the economy of different power level fast reactors with 2,000 EFPD lifetime such as 100 MWt, 300 MWt, 500 MWt, 700 MWt, and 1000 MWt thermal power is designed and analyzed. By analyzing the invention of uranium and 235U and the fuel utilization of different core schemes, the best economic analysis of the single reactor power of the current lead-based modular reactor is proposed and the foundation of the lead-based modular nuclear power is provided.

Because of the double-heterogeneity (DH), dispersed particle-type systems cannot be described by traditional neutronic programs, and the volumetric homogenization method (VHM) will bring reactivity calculation deviation because of ignoring the spatial self-shielding effect of the particles. In this article, the relationship between the reactivity calculation deviation and the optical length of dispersed particle-type fuel and different types of burnable poisons is analyzed. Also then, it was proposed that the influencing factors of reactivity calculation deviation can be integrated to a physical quantity named theoretically modified optical length containing the influencing factors mentioned earlier. In addition, the DH physical boundary has forward that, when the theoretically modified optical length is larger than 10−4, reactivity calculation deviation of volumetric homogenization method will be larger than 100 pcm, and the DH of the dispersed particle-type systems should be considered.

Based on the requirement of Hexagonal Casing Type Fuel Reactor (HCTFR) nuclear design and the critical physical experiment design method introduced by a single factor, 11 core critical physical experiments are proposed to validate the calculation accuracy and reliability of the nuclear design code CPLEV2. The experiment loading scheme fully takes into account the various components and more than one irradiate hole in the HCTFR core, which is used as critical physical experiment schemes successfully. According to the critical physical experiment data, the reactivity calculation deviations of all critical physical experiments are within ±1.0%. The validation results show that the nuclear design code CPLEV2 has high calculation accuracy and reliability for the core of hexagonal casing type fuel, and it can be used for HCTFR nuclear design.

Because the elastic scattering cross sections of medium-mass nuclides have very strong elastic scattering resonance phenomenon in the fast neutron region, which will lead to the self-shielding effect of energy scale and make distortions of the neutron flux distribution to zigzagging. In order to accurately describe the distribution of neutron flux in the energy scale, the deterministic one-step method needs to divide a large number of energy intervals for description, and the number of energy groups is generally thousands. Deterministic one-step transport calculation has large memory and low computational efficiency with thousands of groups. In the traditional calculation of the whole-core non-uniform transport calculation for the thousands of groups, the section generation software was mainly used to prepare the self-shielding cross section by using the ultra-fine groups, and then the broad-group cross section was prepared offline by the transport calculation of the equivalent model of cells or components. Finally, the deterministic one-step program was used to calculate the whole-core non-uniform transport. The broad-group cross sections prepared off-line cannot reflect the characteristics of materials of different reactor locations and bring the approximations. In order to solve the problem that the thousand-group energy structure of fast reactors leads to the high computational cost of the deterministic one-step method, an online energy group condensation method with fine group energy spectrum based on SHARK was developed. For the fuel cells of fast reactors, it can keep the composition of fuel and other materials unchanged and search the radius of the fuel to make the escape cross section conserved. It has the capability of online equivalent model establishment, online calculation of fine group energy spectrum and broad group cross sections condensation. For non-fuel cells, the broad group cross section was condensed using the fine group energy spectrum calculated by the one-dimensionalal constant volume model of practical problems. Based on the MOX1000 material of the benchmark for neutronic analysis of sodium-cooled fast reactor cores, a two-dimensional 5×5 rectangular single-assembly problem and a two-dimensional 3×3 multi-assembly problem were constructed and calculated. The numerical results show that compared with the calculation results of the group in 1 968, the acceleration ratio of the online energy group condensation method in the two-dimensional 5×5 rectangular single-assembly problem is 8 to 18 and that in the two-dimensional 3×3 multi-assembly problem is 12 to 17, which can significantly improve the calculation efficiency. In terms of calculation accuracy, the relative deviation of pin power distribution is less than 1%, and the maximum deviation of eigenvalue is about 360 pcm. It is of great significance to deterministic one-step method for fast reactor transport calculation.

The bubble effectiveness in liquid phase cylohexane non-catalytic oxidation process is discussed in this paper. Then the bubble effectiveness and a new proposed kinetic model are used in the mathematical model of the industrial reactor for the cyclohexane non-catalytic oxidation process. Furthermore, simulation and optimization based on this reactor model are carried out. The results of simulation show that the reactor model using the concept of bubble effectiveness agrees better with the plant data, and the results of optimization are much better than the present industrial production level, which will help to improve the operation of the reactor section and design of new installations.

In recent years, particulate burnable poisons have attracted much attention due to their superior properties and are widely used in various reactor design. It is uniformly distributed in the fuel cell, does not occupy the position of the fuel element, and will not cause distortion of the power distribution. Dispersed particulate poisons have multiple dimension for adjustment and optimization, including sizes of particles, concentrations and type of poison particles. They can be adjusted according to actual needs, which can effectively and long-term control the reactive process, with strong flexibility. However, they have special spatial structure and strong spatial self-shielding effect, which leads to microscopic stratification during the burnup process. In numerical simulation, the direct refined solution will bring a huge amount of calculation and great grid density, which has certain challenges. Therefore, a new burnup calculation method based on multi-scale coupling was proposed in this paper. First of all, a new parameter named effective burnable poison proportion fv was defined and a microscopic fine spherical model was built according to the target cell model. Secondly, equivalent homogenization, which was based on the reactivity equivalence strategy, was performed and the fine spherical model was modified into a microscopic homogeneous spherical model. It could provide important parameters for macroscopic model. By coupling of the microscopic spherical model and the macroscopic cell model, the fine solution problem of the dispersed particulate media was simplified into a fast solution of a simple conventional media. It solves the problems of large amount of calculation and high grid density in the process of solving the fine burnup of the dispersed particulate poison in the global scope, accurately characterizes the burnup characteristics of the dispersed particulate poison, which provides a novel idea for the solution of the dispersed particulate media. Later preliminary verification was provided. Compared with current collision probability method, the new algorithm has an overall error in effective multiplication factor at about 200 pcm, while the initial error is 100 pcm. However, a relative high error in the middle and late stages burnup periods is detected. Luckily, this period lasts for a short time. When the burnable poison is burnt out, the error returns to normal level (about 200 pcm). The new algorithm has an error in thermal neutron flux level within 1.25%, and the average error level of the burnable poison number density is 1.41%. In general, the new algorithm is proved to have great performance in neutron physical parameters such as effective multiplication factor, neutron flux density and nuclide number density. Besides, it would be promising in future large-scale computation.

Abstract Background A new algorithm for assessing similarity between primer and template has been developed based on the hypothesis that annealing of primer to template is an information transfer process. Results Primer sequence is converted to a vector of the full potential hydrogen numbers (3 for G or C, 2 for A or T), while template sequence is converted to a vector of the actual hydrogen bond numbers formed after primer annealing. The former is considered as source information and the latter destination information. An information coefficient is calculated as a measure for fidelity of this information transfer process and thus a measure of similarity between primer and potential annealing site on template. Conclusion Successful prediction of PCR products from whole genomic sequences with a computer program based on the algorithm demonstrated the potential of this new algorithm in areas like in silico PCR and gene finding.

New type reactors usually adopt advanced fuel types and more anisotropic fuel arrangements, the neutron spectrum is very different from that of pressurized water reactor, and the neutron anisotropy is stronger. If using the neutron transport theory, although better results can be obtained, the computational efficiency is low. If the traditional diffusion theory is used, the calculation efficiency can be improved, however, the complex neutron energy spectrum and strong neutron anisotropy in the core decrease the calculation accuracy. In this study, the core calculation and analysis method based on quasi-diffusion equation was employed. One of the basic assumptions established by traditional diffusion theory is that the angular flux of neutrons is a first-order function of angle, but the quasi-diffusion equation does not adopt this assumption, and an Eddington factor is used to express product of the angular flux of neutrons and angle vectors. The Eddington factor can describe the anisotropic characteristics that cannot be reflected by traditional diffusion theory, and the form of quasi-diffusion equation is similar to the traditional diffusion equation. Most of the current researches applied the quasi-diffusion equation to accelerate the calculation neutron transport. Due to the computational complexity of the Eddington factor, the studies on the quasi-diffusion equation independently employed to the reactor calculation, especially for the reactor with hexagonal assembly are insufficient. Aiming at the characteristics of nonlinear calculation of the Eddington factor, this study regarded the Eddington factor as a special few-group constant based on “two-step” method, and adopted Monte Carlo code SERPENT of better neutron energy spectrum adaptability to calculate. For three-dimensional multi-group quasi-diffusion equation, based on Galerkin variation principle and Lagrange multiplier method, this study established a functional including the nodal balance relationship and boundary condition in the entire region, and used the Ritz discrete method to expand this functional by orthogonal basis function. Then the response relation between nodal neutron flux density and neutron current was built to solve the quasi-diffusion equation, and a code named VNMQD for reactor core with hexagonal assembly was developed. The VNMQD code was verified by using 3D VVER1000 benchmark, RBWR single assembly problem and 3D BN600 simplified model. The results show that the VNMQD code is developed correctly. For the core with strong anisotropy problem, VNMQD has a great improvement in the calculation accuracy for the effective core multiplication factor and neutron flux density compared with traditional diffusion calculation, and the calculation efficiency of both is similar. VNMQD achieves a balance between calculation accuracy and calculation efficiency.

Background: Nonalcoholic fatty liver disease (NAFLD) has become a major global health burden, which increases the risk of extra-hepatic complications such as type 2 diabetes mellitus (T2DM), dyslipidemia, metabolic syndrome (MetS), and cardiovascular disease (CVD). However, NAFLD remains underappreciated and underdiagnosed. Our study aimed to explore the prevalence of NAFLD and the association between NAFLD and CVD events among adults aged 40 and older in Northern China. Methods: This study was conducted in the Shijingshan district of Beijing, China from November 2011 to August 2012. A total of 18891 subjects were recruited in the study. The information including demographical information, lifestyle, previous history of diabetes, hypertension, dyslipidemia, CVD, and liver disease were gathered. Data on physical examination, blood lipid profile, fasting blood glucose, and 2-hour blood glucose were recorded. Determination of MetS was according to T2DM guideline of Chinese Diabetes Society (2020 edition). The association between CVD and NAFLD was evaluated by multivariate logistic regression. Results: The prevalence of NAFLD was 15.2%. After adjustment for age, smoking status, alcohol intake, WC, hypertension, dyslipidemia and hyperglycemia, the odds ratios (ORs) of CVD in men were 1.622 (95%CI: 1.345– 1.957) and 1.990 (95%CI: 1.709– 2.316) in women with NAFLD, compared with the subjects without NAFLD. Conclusions: NAFLD is independently associated with increased risk of CVD development. [ABSTRACT FROM AUTHOR]

To address the efficiency bottleneck encountered in reactor design calculations for the newly developed lead-based reactor neutronics analysis code system MOSASAUR, we recently developed acceleration functions based on various coarse-mesh finite difference (CMFD) methods and spatial domain decomposition parallel algorithm. However, the applicability of these improvements to different lead-based reactors remains to be analyzed. This work collected and established core models for various types of lead-based reactor. Based on different SN nodal transport solvers, we analyzed the acceleration performance of different CMFD methods, different CPU cores, and the combination of CMFD and parallel calculation. The results indicated that the impact of different CMFD acceleration or parallel acceleration on the calculation accuracy was negligible; the rCMFD method had good stability and convergence rate, achieving speedup of several to dozens; parallel efficiency was related to the number of meshes, and for large reactor cores, superlinear speedup was achieved with 200 CPU cores; rCMFD and parallel computing could achieve combined speedup, with 200 cores achieving speedup of hundreds to thousands, typically completing a reactor core transport calculation in 1 min. [ABSTRACT FROM AUTHOR]

Long-term care insurance is beneficial for boosting household consumption, thereby holding significant value in promoting economic recovery and sustainability. Despite its potential impact, the relationship between them have not been sufficiently studied. This paper aims to scrutinize the impact of long-term care insurance on household consumption and sustainability, leveraging data from the CHARLS survey spanning the years 2011 to 2018. The empirical findings reveal that: (1) firstly, the implementation of long-term care insurance has led to a substantial 20.6% increase in household subsistence consumption, and a 2.9% rise in developmental consumption. Furthermore, it has effectively diminished the proportion of subsistence consumption within the overall consumption framework by 2.2%. (2)Secondly, the augmentation of household consumption through long-term care insurance is elucidated by various mechanisms. Notably, it has stimulated labor force participation, curtailed medical expenses, and mitigated the necessity for precautionary savings. These dynamics collectively contribute to an enhanced capacity for household consumption, further reinforcing the economic benefits associated with long-term care insurance. In the context of the ongoing global challenges, particularly the aftermath of the COVID-19 pandemic, our analysis underscores the potential of long-term care insurance not only in facilitating economic recovery, but also in fortifying sustainability. As policymakers contemplate strategies for post-pandemic recovery, it is imperative for the government to consider expanding the pilot scope of long-term care insurance initiatives, which promotes economic resilience and sustains household well-being in the face of unforeseen challenges. [ABSTRACT FROM AUTHOR]