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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.

Here, a wideband absorptive frequency‐selective reflector (AFSR) based on a split‐ring resonator (SRR) embedded with chip resistors is proposed. The wide absorption band is achieved by the multimode resonances of two dipoles, and the insertion of SSRs is able to bypass the losses in the passband, thus allowing to open a wide window in addition to achieving broadband absorption performance. The upper structure consists of a dipole in series with two SSRs, while the lower dipole connects one SSR. The upper and lower structures are grouped together and rotated by 90° around the Z‐axis to form the final dual‐polarization 3D‐AFSR. The simulated results demonstrate that reflection coefficients below −10 dB are seen between 6.74–9.31 and 16.91–19.61 GHz under normal incidence, with a total fractional bandwidth of 46.8%. It also has a wide 3 dB reflection band which is obtained from 10.69 to 15.44 GHz, and the entire profile is 0.17λL, where λL is lowest operating frequency. [ABSTRACT FROM AUTHOR]

Background: The prevalence of malnutrition is unknown in patients with Hirschsprung disease. Undernutrition is associated with poor clinical outcomes. This study aims to describe the nutrition status among patients with Hirschsprung disease at admission. Methods: We retrospectively used data from children with Hirschsprung disease admitted to three pediatric surgery centers in China from January 2016 to December 2020. The weight‐for‐age z scores (WAZ), height‐for‐age z scores (HAZ), and body mass index‐for‐age z scores (BAZ) were calculated as the reference for nutrition risk according to the World Health Organization child growth standards. The nutrition status of enrolled children was described and nutrition risk in each clinical characteristic was compared. The association between nutrition status and clinical outcomes was analyzed using univariate and multivariate logistic regression. Results: A total of 624 patients were included in this study. The mean WAZ, HAZ, and BAZ of all patients was −0.64 ± 1.40, −0.45 ± 1.78, and −0.43 ± 1.50, respectively. Moderate to severe overall undernutrition was 16.3% (102/624). We found that WAZ and BAZ were significantly reduced with the length of aganglionic segments (P = 0.001). Children who had a definitive surgery at 3 years of age or older had significantly lower HAZ (P = 0.001). A multivariate regression model assessing postoperative Hirschsprung‐associated enterocolitis showed that the WAZ was one of the independent risk factors (P = 0.001). Conclusion: Undernutrition is prevalent among children with Hirschsprung disease. Nutrition assessment to identify individuals at risk of undernutrition for further intervention is necessary. [ABSTRACT FROM AUTHOR]