Flow blockage analysis for fuel assembly in a lead-based fast reactor

Wang, Chenglong,Wu, Di,Gui, Minyang,Cai, Rong,Zhu, Dahuan,Zhang, Dalin,Tian, Wenxi,Qiu, Suizheng,Su, G.H. Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.10

Flow blockage of the fuel assembly in the lead-based fast reactor (LFR) may produce critical local spots, which will result in cladding failure and threaten reactor safety. In this study, the flow blockage characteristics were analyzed with the sub-channel analysis method, and the circumferentially-varied method was employed for considering the non-uniform distribution of circumferential temperature. The developed sub-channel analysis code SACOS-PB was validated by a heat transfer experiment in a blocked 19-rod bundle cooled by lead-bismuth eutectic. The deviations between the predicted coolant temperature and experimental values are within ±5%, including small and large flow blockage scenarios. And the temperature distributions of the fuel rod could be better simulated by the circumferentially-varied method for the small blockage scenario. Based on the validated code, the analysis of blockage characteristics was conducted. It could be seen from the temperature and flow distributions that a large blockage accident is more destructive compared with a small one. The sensitivity analysis shows that the closer the blockage location is to the exit, the more dangerous the accident is. Similarly, a larger blockage length will lead to a more serious case. And a higher exit temperature will be generated resulting from a higher peak coolant temperature of the blocked region. This work could provide a reference for the future design and development of the LFR.

Thermal-hydraulic analysis of a new conceptual heat pipe cooled small nuclear reactor system

Wang, Chenglong,Sun, Hao,Tang, Simiao,Tian, Wenxi,Qiu, Suizheng,Su, Guanghui Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.1

Small nuclear reactor features higher power capacity, longer operation life than conventional power sources. It could be an ideal alternative of existing power source applied for special equipment for terrestrial or underwater missions. In this paper, a 25kWe heat pipe cooled reactor power source applied for multiple use is preliminary designed. Based on the design, a thermal-hydraulic analysis code for heat pipe cooled reactor is developed to analyze steady and transient performance of the designed nuclear reactor. For reactor design, UN fuel with 65% enrichment and potassium heat pipes are adopted in the reactor core. Tungsten and LiH are adopted as radiation shield on both sides of the reactor core. The reactor is controlled by 6 control drums with B₄C neutron absorbers. Thermoelectric generator (TEG) converts fission heat into electricity. Cooling water removes waste heat out of the reactor. The thermal-hydraulic characteristics of heat pipes are simulated using thermal resistance network method. Thermal parameters of steady and transient conditions, such as the temperature distribution of every key components are obtained. Then the postulated reactor accidents for heat pipe cooled reactor, including power variation, single heat pipe failure and cooling channel blockage, are analyzed and evaluated. Results show that all the designed parameters satisfy the safety requirements. This work could provide reference to the design and application of the heat pipe cooled nuclear power source.

Experimental study on the Influence of Heating Surface Inclination Angle on Heat Transfer and CHF performance for Pool Boiling

Chenglong Wang,Panxiao Li,Dalin Zhang,Wenxi Tian,Suizheng Qiu,G.H. Su,Jian Deng 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1

Pool boiling heat transfer is widely applied in nuclear engineering fields. The influence of heating surface orientation on the pool boiling heat transfer has received extensive attention. In this study, the heating surface with different roughness was adopted to conduct pool boiling experiments at different inclination angles. Based on the boiling curves and bubble images, the effects of inclination angle on the pool boiling heat transfer and critical heat flux were analyzed. When the inclination angle was bigger than 90°, the bubble size increased with the increase of inclination angle. Both the bubble departure frequency and critical heat flux decreased as the inclination angle increased. The existing theoretical models about pool boiling heat transfer and critical heat flux were compared. From the perspective of bubble agitation model and Hot/Dry spot model, the experimental phenomena could be explained reasonably. The enlargement of bubble not only could enhance the agitation of nearby liquid but also would cause the bubble to stay longer on the heating surface. Consequently, the effect of inclination angle on the pool boiling heat transfer was not conspicuous. With the increase of inclination angle, the rewetting of heating surface became much more difficult. It has negative effect on the critical heat flux. This work provides experimental data basis for heat transfer and CHF performance of pool boiling.

Molecular dynamics study of liquid sodium film evaporation and condensation by Lennard-Jones potential

Wang Zetao,Guo Kailun,Wang Chenglong,Zhang Dalin,Tian Wenxi,Qiu Suizheng,Su Guanghui 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.8

Deeply understanding the phase change of thin liquid sodium film inside wick pore is very important for further studying high-temperature sodium heat pipe's heat transfer. For the first time, the evaporation and condensation of thin liquid sodium film are investigated by the Lennard-Jones potential of molecular dynamics. Based on the startup and normal operation of the sodium heat pipe, three different cases are simulated. First, the equilibrium is achieved and the Mass Accommodation Coefficients of the three cases are 0.3886, 0.2119, 0.2615 respectively. Secondly, the non-equilibrium is built. The change of liquid film thickness, the number of gas atoms, the net evaporation flux (Jnet), the heat transfer coefficient (h) at the liquid-gas interface are acquired. Results indicate that the magnitude of the Jnet and the h increase with the basic equilibrium temperature. In 520e600 K (the startup of the heat pipe), the h has approached 5 e6Wm2 K1 while liquid film thickness is in 11e13 nm. The fact shows that during the initial startup of the sodium heat pipe, the thermal resistance at the liquid-gas interface can't be negligible. This work is the complement and extension for macroscopic investigation of heat transfer inside sodium heat pipe. It can provide a reference for further numerical simulation and optimal design of the sodium heat pipe in the future.

Numerical study of oxygen transport characteristics in lead-bismuth eutectic for gas-phase oxygen control

Wang, Chenglong,Zhang, Yan,Zhang, Dalin,Lan, Zhike,Tian, Wenxi,Su, Guanghui,Qiu, Suizheng Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.7

One-dimensional oxygen transport relation is indispensable to study the oxygen distribution in the LBE-cooled system with an oxygen control device. In this paper, a numerical research is carried out to study the oxygen transport characteristics in a gas-phase oxygen control device, including the static case and dynamic case. The model of static oxygen control is based on the two-phase VOF model and the results agree well with the theoretical expectation. The model of dynamic oxygen control is simplified and the gas-liquid interface is treated as a free surface boundary with a constant oxygen concentration. The influences of the inlet and interface oxygen concentration, mass flow rate, temperature, and the inlet pipe location on the mass transfer characteristics are discussed. Based on the results, an oxygen mass transport relation considering the temperature dependence and velocity dependence separately is obtained. The relation can be used in a one-dimensional system analysis code to predict the oxygen provided by the oxygen control device, which is an important part of the integral oxygen mass transfer models.

Thermal-hydraulic analysis of He-Xe gas mixture in 2×2 rod bundle wrapped with helical wires

Chenglong Wang,Siyuan Chen,Wenxi Tian,G.H. Su,Suizheng Qiu Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.7

Gas-cooled space reactor, which adopts He-Xe gas mixture as working fluid, is a better choice for megawatt power generation. In this paper, thermal-hydraulic characteristics of He-Xe gas mixture in 2×2 rod bundle wrapped with helical wires is numerically investigated. The velocity, pressure and temperature distribution of the coolant are obtained and analyzed. The results show that the existence of helical wires forms the vortexes and changes the velocity and temperature distribution. Hot spots are found at the contact corners between helical wires and fuel rods. The highest temperature of the hot spots reach 1600K, while the mainstream temperature is less than 400K. The helical wire structure increases the friction pressure drop by 20%-50%. The effect extent varies with the pitch and the number of helical wires. The helical wire structure leads to the reduction of Nusselt number. Comparing thermal-hydraulic performance ratios (THPR) of different structures, the THPR values are all less than 1. It means that gas-cooled space reactor adopting helical wires could not strengthen the core heat removal performance. This work provides the thermal-hydraulic design basis for He-Xe gas cooled space nuclear reactor.

Visualizing the distributions and spatiotemporal changes of metabolites in Panax notoginseng by MALDI mass spectrometry imaging

Chenglong Sun,Shuangshuang Ma,Lili Li,Daijie Wang,Wei Liu,Feng Liu,Lanping Guo,Xiao Wang 고려인삼학회 2021 Journal of Ginseng Research Vol.45 No.6

Background: Panax notoginseng is a highly valued medicinal herb used widely in China and many Asiancountries. Its root and rhizome have long been used for the treatment of cardiovascular and hematologicaldiseases. Imaging the spatial distributions and dynamics of metabolites in heterogeneous planttissues is significant for characterizing the metabolic networks of Panax notoginseng, and this will alsoprovide a highly informative approach to understand the complex molecular changes in the processing ofPanax notoginseng. Methods: Here, a high-sensitive MALDI-MS imaging method was developed and adopted to visualize thespatial distributions and spatiotemporal changes of metabolites in different botanical parts of Panaxnotoginseng. Results: A wide spectrum of metabolites including notoginsenosides, ginsenosides, amino acids, dencichine,gluconic acid, and low-molecular-weight organic acids were imaged in Panax notoginseng rhizomeand root tissues for the first time. Moreover, the spatiotemporal alterations of metabolites during thesteaming of Panax notoginseng root were also characterized in this study. And, a series of metabolitessuch as dencichine, arginine and glutamine that changed with the steaming of Panax notoginseng weresuccessfully screened out and imaged. Conclusion: These spatially-resolved metabolite data not only enhance our understanding of the Panaxnotoginseng metabolic networks, but also provide dire

Study on Wear Prediction of Shield Disc Cutter in Hard Rock and Its Application

Zhenyong Wang,Chenglong Liu,Yusheng Jiang,Linwei Dong,Shixian Wang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.3

It is important to enable the prediction of disc cutter wear during shield tunnelling through hard rock because such wear is associated with project delays and increased costs. Based on a theoretical analysis of Archard’s wear mechanism and Euler’s rotation theorem, a displacement equation of rock-breaking point A on the disc cutter ring is studied, and then a new wear prediction model is established combined with the theoretical analysis of the disc cutter force and wear test. The cutter wear prediction model is verified by using the data of two cases, and the results reveal that the errors between measured and predicted values are less than 25%. The research results also show that abrasive wear is the main wear mechanism (approximately 88%). In addition, the influence of fatigue wear is very small, accounting for only approximately 2%, which can be ignored. Finally, the maximum tunneling distance of disc cutters under different installation radii and penetration is studied using the model, and the results can be used as references for optimizing shield tunneling parameters and predicting the disc cutter replacement time.

The “living” Feature of the ATRP Macroinitiators in Different Catalytic Systems

Yazhen Wang,Li Liu,Shaobo Dong,Xilai Zhou,Chenglong Wang,Zhen Shi 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.2

Atom transfer radical polymerization (ATRP) has achieved widespread use in living polymerization. However, until now there hasbeen little report that macroinitiators initiate polymerization in different catalytic systems. The preparation of bromine-terminatedpolymethyl methacrylate (PMMA-Br) and chlorine-terminated PMMA (PMMA-Cl) were carried out via reverse atom transferradical polymerization (RATRP). The PMMA with halogen termination and narrow polydispersity (Mn = 12,000–15,000 g/mol,Mw/Mn = 1.1–1.2) were used as macroinitiators. The block copolymer of polymethyl methacrylate and polyacrylonitrile (PMMAb-PAN) was prepared in different catalytic systems through normal ATRP. The analyses of the 1H NMR showed that the PMMAprepared by RATRP were end-functionalized by halogen atoms, demonstrated the activities of the PMMA macroinitiators. Themolecular weight and polydispersity index (PDI) of the polymers were analyzed using gel permeation chromatography (GPC). The results indicated that the block polymers that the molecular weight of the block copolymer after chain extension has increasedsignificantly and the molecular weight distribution is narrow (Mn = 17,000–25,000 g/mol, Mw/Mn = 1.1–1.3). The kinetics ofthese polymerization processes were studied as a function of monomers to the macroinitiator molar ratio. It was found that thepolymerizations in different catalytic systems coincidence first-order kinetics with respect to monomers.

Synthesis of aminated calcium lignosulfonate and its adsorption properties for azo dyes

Yingying Wang,Linli Zhu,Xiaohong Wang,Wanru Zheng,Chen Hao,Chenglong Jiang,Jingbo Wu 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.61 No.-

A low-cost adsorbent, aminated calcium lignosulfonate (ACLS) was prepared and successfully applied to the adsorption of Congo red and the Titan yellow dyes. The adsorbent was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), elemental mapping images (EMIs) and Brunauer–Emmett–Teller (BET) analysis. And the efficiency of ACLS for the removal of Congo red and the Titan yellow dyes was evaluated by several factors, such as temperature, pH, adsorbent dose, contact time and initial concentration of dyes solution. And the test ranges of temperature, pH, adsorbent dose, contact time and initial concentration of dye solution were 25–45 °C, 2–12, 0.005–0.05 g, 1–48 h, 10–200 mg L−1, respectively. The adsorption results demonstrated a good ability to remove dye with the removal rates of 97% and 91% for 30 mg L−1 Congo red and 40 mg L−1 Titan yellow, respectively. The adsorption kinetic and adsorption isotherms can be well described by the pseudo second order kinetic and the Langmuir isotherm model for the both dyes, respectively. Moreover, the maximum adsorption capacity of Congo red and Titan yellow reached 258.4 mg g−1 and 190.1 mg g−1 in the study of the Langmuir adsorption isotherm, respectively. Thermodynamic studies show that the adsorption of the two dyes is a spontaneous endothermic process. The results indicate that the ACLS has the potential to be used in the treatment of dye wastewater.