Main Pump Research Articles

Thermal-Hydraulic Transient Analyses for Primary Coolant System of HFRR Using RELAP5

The High Flux Research Reactor (HFRR) is a 40 MW pool-type nuclear research reactor developed for neutron beam tube research, material and fuel irradiation studies, and advanced research using a cold neutron source. As a part of safety analyses, thermal-hydraulic transient analyses were carried out using the computer coder RELAP5 for the primary coolant system of the HFRR. This technical note presents various analyses that were carried out such as loss of normal electric power supply, loss of heat sink, main coolant pump seizure, inadvertent opening of a natural circulation valve, and loss-of-coolant accident considering breaks in the pump suction line and pump discharge line. It is demonstrated that fuel cooling is ensured and safety parameters are well within acceptable limits.

Numerical simulation of centrifugal pump impeller erosion caused by particles in lead–bismuth alloy

In order to study the influence of solid particles in lead–bismuth alloy on the safety of nuclear main pump, DPM (Discrete Phase Model) is used to calculate the wear rate of the impeller of nuclear main pump under different operating conditions. By comparing the erosion rate and the most severe erosion area under different working conditions, the most unfavorable operating conditions are obtained. The results show that the erosion of impeller caused by solid particles is the most serious when the inlet velocity of particles u is 0.4[Formula: see text]m/s and particle size D is 100[Formula: see text][Formula: see text]m. Under the small particle size, the impeller erosion concentrated on the suction side of the blade, and under the large particle diameter, the erosion concentrated on the pressure side, and the erosion is more serious. With the increase of solid particle velocity, the erosion of the impeller increases first and then decreases. The erosion severity of impeller and front and rear cover plates caused by solid particles is not consistent. The above research can provide guidance for the anti-wear design and safe operation of the nuclear main pump impeller.

OPTIMIZATION OF GEOMETRIC PARAMETERS OF HELICAL CHANNELS IN A MOLECULAR VACUUM PUMP

A method of optimization of geometrical parameters of a molecular stage of a turbomolecular vacuum pump with helical channels made on the stator under the molecular gas flow regime is considered. In axial section of stator the channels have rectangular shape. As a result of numerical experiments, the influence of each geometrical parameter on the main pumping characteristics of the molecular stage has been determined by the Monte-Carlo method.

Health State Identification Method of Nuclear Power Main Circulating Pump Based on EEMD and OQGA-SVM

Main circulation pump is the only high-speed rotating equipment in primary loop of nuclear power plant. Its function is to ensure the normal operation of primary loop system by controlling the circulating flow of reactor coolant. In order to ensure long-term healthy operation of nuclear power main circulating pump, a method for identifying the health states of nuclear power main circulating pump based on ensemble empirical mode decomposition (EEMD) and support vector machine optimized by optimized quantum genetic algorithm (OQGA-SVM) is proposed. Vibration signal of main circulating pump is decomposed by EEMD. Vibration signal characteristics of nuclear power main circulating pump in healthy state and different fault states are analyzed and target characteristic indexes are put forward. Then, health state identification model of main circulation pump of OQGA-SVM is established, and target characteristic indexes are used as input parameter of the model. Finally, combined with experimental data, the model analysis and validation show that the health state identification method of nuclear power main circulating pump based on EEMD-OQGA-SVM can accurately and effectively identify the states of main circulation pump, has a higher identification accuracy than EEMD-SVM method and is more efficient and accurate than EEMD-QGA-SVM method.

Analysis of the safety of pumping units of pumping stations of machine water lifting in the function of reliability indicators

The article presents ways of analyzing the safety of pumping units of pumping stations of machine water lifting in the function of reliability indicators, taking into account the complexity of analyzing the safety of pumping stations of machine water lifting and presenting the pumping unit of a pumping station as a "system", as well as taking into account the need to attract information about their functional scheme, information about the reliability indicators of the elements included in these schemes, information about the adopted system of maintenance and repair, as well as the criteria for the failure of such systems, structural schemes for calculating the reliability of the pumping unit have been developed. The developed structural scheme for calculating the reliability of a pumping unit is presented, consisting of an electric motor, a pump, a power supply network, a control device, a converter, a machine exciter or a semiconductor excitation system, a winding, active steel, an excitation winding, a collector-brush apparatus, a bearing, guide bearings, an oil cooler, an air cooler of an electric motor, a working ring, guide bearings, system lubrication of pump bearings. Structural diagrams are also given for four variants of the design layout of pumping units: each pumping unit supplies water to its pipeline; several pumping units operate in one common pressure pipeline; the main and backup pumping units are connected in series; pumping units are connected to a common pressure pipeline in series-parallel. Based on these structural schemes, formulas for determining the probability of trouble-free operation of the pumping unit and pumping units, considering their structural layout, are compiled. The article assumes that the uptime of the synchronous motor of the pumping unit is distributed exponentially, and the law of the repair time distribution corresponds to the gamma distribution.

Study on the Hydraulic Performance of the Axial Flow Main Coolant Pump for Lead-Cooled Fast Reactor

Study on the Hydraulic Performance of the Axial Flow Main Coolant Pump for Lead-Cooled Fast Reactor

The impact of the Serasi program on increasing production and revenue of swamp pad farmers

The SERASI (Save Rawa Prosperous Farmers) program is an effort to increase the planting index and productivity through land optimization activities that are integrated with efforts to improve the standard of living of farmers through assistance in developing irrigation systems in swamplands. This study aims to: (1) Describe the implementation of the SERASI Program, (2) Describe the benefits obtained by farmers receiving the SERASI Program. (3) Analyze the differences in production and income before and after receiving the SERASI Program. (4) Analyze the impact of the SERASI Program on the production and income of the recipients of the SERASI Program. The data analysis method used is descriptive analysis, income analysis and statistical analysis of the Wilcoxon difference test. The respondents of this study were farmers receiving the SERASI Program. The research location is in Awang Cenrana Village, Cenrana District, Bone Regency. The results showed that (1) the implementation of the SERASI Program in Awang Cenrana Village, Cenrana District, Bone Regency went well from the planning, construction and evaluation stages. (2) Farmers receive benefits such as construction and repair of irrigation canals, assistance for main water pumps, assistance for production facilities, increased frequency of planting and assistance with assistance. (3) There are differences in the production and income of farmers, where the production and income of farmers increases after receiving the SERASI Program. (4) The very significant difference in production and income illustrates the positive impact of the SERASI Program on rice production and farmers' income.

СОСТАВ И РАСПОЛОЖЕНИЕ ГИДРОТЕХНИЧЕСКИХ СООРУЖЕНИЙ МЕЛИОРАТИВНЫХ НАСОСНЫХ СТАНЦИЙ

Purpose: to analyze the composition and location of waterworks of reclamation pumping stations. Discussion. The object of research is the waterworks included in the reclamation pumping stations while designing. In the course of the research, the search, analysis and systematization of scientific, technical, regulatory and reference documentation, as well as modern developments in the field of design and calculation of reclamation pumping stations were carried out. During the research, the analytical, comparative and logical methods were used. It has been found that reclamation pumping stations can be both irrigation, drainage, including polder, and for agricultural water supply. The main features of each type of pumping stations are identified according the mode of their operation, the quality of the water supplied, water levels, performance seasonality, durability, type of water source, type of water intake, the need to supply sewage or livestock effluents, the likelihood of flooding and other parameters that affect the composition and location of waterworks. Based on these data, the types of waterworks that can be a part of various reclamation pumping stations have been determined. Conclusions. As a result of the research, the composition of the main and auxiliary reclamation pumping stations facilities was determined. The main layout of typical pumping station structures and their location, layout of irrigation pumping stations facilities used for irrigation with wastewater or livestock effluents, conditions for installing pumping station facilities into the water source course during designing are determined. The results obtained make it possible to apply these provisions in the development of regulations on the design standards for waterworks of reclamation pumping stations that are part of them.

Elements of technical water supply system of pumping units

The ongoing research aims to develop an optimal variant of the industrial water supply scheme, selected based on a comparison of several possible solutions. It is recommended to use a block-by-aggregate technical water supply system at stations equipped with any number of main units with a large flow of the main pumps, more than 5 m3/s. If there is a significant amount of sediment in the water at the stations, settling tanks are needed at the water intake devices of the technical water supply systems. Filling with water from pumps installed above the source level can be performed using vacuum pumps, ejectors, the self-suction method, using suction pipes with a raised elbow, or storage tanks. The authors investigated a new process water supply system for a large pumping station in Kiziltepa with control devices and a flow meter on the service water supply inlet pipeline. The calculation of the reliability of the operation of the described structures includes a new reliability criterion, which is taken as the turbidity of the flow at the outlet of the settler.

Transient analysis of a locked rotor/shaft seizure accident involving the EU-DEMO WCLL Breeding Blanket primary cooling circuits

The EU-DEMO Water-Cooled Lithium-Lead (WCLL) Breeding Blanket (BB) main subsystems to be cooled are the Breeder Zone (BZ) and the First Wall (FW). Each subsystem will be equipped with an independent Primary Heat Transfer System (PHTS). Within the framework of the EUROfusion Work Package Breeding Blanket research program, several accidents belonging to the category of “Decrease in Coolant System Flow Rate” were studied. The activity was aimed at evaluating the blanket and primary cooling systems thermal-hydraulic performances during such transient conditions. A complete model including the BB and related PHTS circuits has been developed at Sapienza University of Rome. A modified version of RELAP5/Mod3.3 system code has been used to perform the calculations. The simulation results showed that a locked rotor/shaft seizure of a BZ or a FW main coolant pump is the most challenging scenario. BZ and FW system behavior has been analyzed following this initiating event with the goal of the design improvement and to individuate the need for preventive measures. The influence of loss of off-site power on the accident evolution has also been investigated. Moreover, management strategies have been proposed for different reactor components. Calculations demonstrate that the current blanket and PHTS design is appropriate to cope with these kinds of accident scenarios.

MEDIUM SIZE LNG TANKER LUBRICATING SYSTEM HEAT EXCHANGER (COOLER) ANALYSIS

As part of the project, the necessary steps are taken to carry out a calculation of a main engine lubrication system fitted on board an LNG tank vessel with a capacity of 45,000 dwt. The validation of the system is achieved by using a calculation program based on finite element theory (CFD). This is a new ship with a series of innovations regarding the construction of the cargo tanks, which was built in 2018. For sure, this engine is a dual fuel type, powered by marine fuel and natural gas. A general description of the naval lubrication system is made, then a specific calculation is performed for the essentials, such as: the main oil pump, the oil storage tanks, the oil separator, the oil filters and the oil cooler. Next, the focus is on the oil cooler, which is considered an essential part of the installation. In the first part of chapter five it is described in detail, from a constructive and functional point of view, then, using the Ansys program, the corresponding calculation is performed to verify it. A model is made according to the geometrical characteristics, then a series of specific simulations are performed. The main purpose of the simulation is to determine de operational behaviour of this heat exchanger from a temperature point of view and to establish its optimal operational status. This cand be done by establishing a proper simulation model and by conducting a precise simulation stage focused and key parameters. As noted in the final part of this study the temperature contour in the heat exchanger for cooled oil flows form minimum 291 0K to maximum 363 0K, this being its optima operational limit.

Dynamic Characteristics of LOX/Kerosene Variable Thrust Liquid Rocket Engine Test System Based on General Modular Simulation Method

For the research demand of reusable LOX/kerosene variable thrust liquid rocket engine, a test system with electric displacement pumps is designed and a multidisciplinary modular dynamic simulation method based on AMESim platform is used to analyze the system. The method comprehensively considers the characteristics of complex components in the engine and realizes the fast module assembly and variable step size solution. Considering the combustion model of thrust chamber, the positive displacement pump model with complex leakage channels, and the cooling jacket heat transfer model, the component dynamic equations are deduced and the final model simulation results reveal that the system has a smooth ignition, stage turning, and shutdown process. The thrust can reach 6900 N in high working condition and the variable thrust ratio is 5 : 1. The dynamic characteristics of the system show that the performance error of main pump components is less than 5%, the maximum average temperature rise of the thrust chamber coolant is about 28°C, and the time of stage adjustment is within 300 ms, which mean the overall design of the system is reasonable. Although the accumulation of LOX before kerosene injection can adversely affect the temperature of the thrust chamber, large pressure pulses do not occur due to the ignitor’s duty flame. Moreover, the pintle injectors based on PID control can effectively stabilize the pressure drop at lower conditions. The system and the simulation method provide important support for the actual engine test and the general LRE dynamic characteristics analysis.

Loss of flow accident analysis in Atucha II nuclear power plant using RELAP5 model

The loss of flow accident (LOFA) in nuclear power plants (NPP) is considered a design base initiating event (DBIE) and it is broadly analyzed in safety and licensing evaluation. Therefore, this is commonly chosen to assess computational models. The current paper addresses the simulation of LOFA under single and total main coolant pump (PMP) trips during full power in Atucha-II Pressurized Heavy Water Reactor (PHWR). RELAP5-mod3.3 NPP was used for solving the thermal-hydraulics, neutron kinetics, and control and safety logic in steady-state and LOFA events. Simulations were assessed against real plant data recorded during a single-PMP trip obtaining very good agreement. After that, the total-PMP trip was simulated, showing that the plant also reached a safe steady condition, guaranteeing the removal of decay heat by natural flow circulation. The very good agreement in terms of the main thermal-hydraulics parameters demonstrated the capability of the computational model to reproduce the overall NPP behavior.

Multi-step prediction of main pump leakage in nuclear power plants with an additive model

With the global demand of clean and low-carbon emission energy sources, safety in the nuclear power industry has gained widespread attention. The accurate and timely long-term fault prognostics of critical equipment in nuclear power plants (NPPs) helps to effectively schedule maintenance, thus reducing operation and maintenance costs while ensuring safety. Unpredictable future load and operations make long-term prediction of time series data in NPPs quite challenging. In this study, we proposed a framework for multi-step prediction based on an empirical mode decomposition (EMD) algorithm, which decomposed complex time series data into several components with simple trends. The useful signal and noise in the components were then divided by a relative ratio method. Candidate prediction models from the model library were trained and tuned on the signal-dominated components. The appropriate model was selected for prediction according to the characteristics of each component signal, and the prediction results were summed and smoothed with an additive model. The proposed method, noted as the denoised EMD method using an additive method (EMD-AM), was applied to the leakage prediction at shaft seals in the reactor coolant pump (RCP) of five different NPPs. Root mean square error (RMSE), mean absolute percentage error (MAPE) and mean absolute scaled error (MASE) were selected to determine the prediction accuracy and uncertainty. Compared with EMD-AM and EMD method using long short-term memory (EMD-LSTM), the experimental results show that the denoised EMD-AM has the overall advantage of simplicity and accuracy.

Occurrence and Variability of the Efflux Pump Gene norA across the Staphylococcus Genus

NorA is one of the main native MDR efflux pumps of Staphylococcus aureus, contributing to reduced susceptibility towards fluoroquinolones and biocides, but little is known about its variability within S. aureus or its distribution and conservation among other staphylococci. We screened for sequences homologous to S. aureus norA and found it in 61 out of the 63 Staphylococcus species described. To the best of our knowledge, this is the first study to report the occurrence of norA across the Staphylococcus genus. The norA phylogenetic tree follows the evolutionary relations of staphylococci and the closely related Mammalliicoccus genus. Comparative analyses suggest a conservation of the NorA function in staphylococci. We also analyzed the variability of norA within S. aureus, for which there are several circulating norA alleles, differing up to 10% at the nucleotide level, which may hamper proper norA detection. We demonstrate the applicability of a PCR-based algorithm to detect and differentiate norA alleles in 52 S. aureus representing a wider collection of 89 isolates from different hosts. Our results highlight the prevalence of norAI and norAII in different settings and the association of norA alleles with specific S. aureus clonal lineages. Ultimately, it confirms the applicability of our PCR-based algorithm to rapidly detect and assign the different norA alleles, a trait that may impact antimicrobial efflux capacity and the search for potential NorA inhibitors.

Thermal load analysis and structure optimization of neutral beam injector cryosorption pump

In order to meet the high vacuum requirement of neutral beam source, cryosorption pump is used as the main pump, and the pumping performance of cryosorption pump depends on its cryogenic performance. To test and verify the feasibility of cryosorption pump steady running, modular design based on cryosorption pump, composed of 16 extraction unit in series, in a single suction unit as the research object, respectively for radiation and cryosorption pump baffle panel of the theory of heat load, and will result in finite element analysis software, the analysis of the temperature field of two structures, respectively and extraction unit structure optimization direction is put forward. The simulation results show that the normal operating temperature of the cryosorption pump can be reached under steady-state operating conditions, and the cryogenic performance of the extraction unit can be improved after the optimization of the structure, thus providing reference for the optimization of the cryogenic pump group.

Experimental study of the polytropic coefficient for hydraulic shock from a decrease in pressure

The article provides an analysis of scientific papers on the study of a hydraulic shock absorber - an air-hydraulic cap, shows that at present there is no consensus on the choice of the numerical value of the polytropic coefficient n. In practice, during the operation of pumping stations with long pressure pipelines, in the event of a sudden power outage, water hammer often occurs to the motors of the main pumps. To prevent this phenomenon, it is convenient to apply a hydraulic shock absorber. The accuracy of calculating the shock absorber depends on the reliable value of the coefficient n. The correct selection of the numerical value of the polytropic coefficient n provides for determining the optimal dimensions of the proposed hydraulic shock absorber. There are different opinions about the choice of the numerical value of n among scientists. N.E. Zhukovsky, when calculating the hydraulic shock absorber, takes n = 1.41. V.S. Dikarevsky accepts n=1.0. Therefore, the rationale for the correct choice of the numerical value of the polytropic coefficient for calculating the absorber in the case of water hammer is very relevant. The paper presents the results of experimental studies of the polytropic coefficient n in a hydraulic shock absorber from a decrease in pressure. When conducting experiments on the study of the absorber, modern scientific instrumentation was used. At the same time, the obtained results of the experiments confirm that the variability of the value of the polytropic coefficient during hydraulic shock in the cap and the correctness of the recommendation of D.A. Fox. The conducted studies prove that the polytropic coefficient has a strictly polytropic character.

Sodium Malonate Inhibits the AcrAB-TolC Multidrug Efflux Pump of Escherichia coli and Increases Antibiotic Efficacy.

There is an urgent need to find novel treatments for combating multidrug-resistant bacteria. Multidrug efflux pumps that expel antibiotics out of cells are major contributors to this problem. Therefore, using efflux pump inhibitors (EPIs) is a promising strategy to increase antibiotic efficacy. However, there are no EPIs currently approved for clinical use especially because of their toxicity. This study investigates sodium malonate, a natural, non-hazardous, small molecule, for its use as a novel EPI of AcrAB-TolC, the main multidrug efflux pump of the Enterobacteriaceae family. Using ethidium bromide accumulation experiments, we found that 25 mM sodium malonate inhibited efflux by the AcrAB-TolC and other MDR pumps of Escherichia coli to a similar degree than 50 μΜ phenylalanine-arginine-β-naphthylamide, a well-known EPI. Using minimum inhibitory concentration assays and molecular docking to study AcrB-ligand interactions, we found that sodium malonate increased the efficacy of ethidium bromide and the antibiotics minocycline, chloramphenicol, and ciprofloxacin, possibly via binding to multiple AcrB locations, including the AcrB proximal binding pocket. In conclusion, sodium malonate is a newly discovered EPI that increases antibiotic efficacy. Our findings support the development of malonic acid/sodium malonate and its derivatives as promising EPIs for augmenting antibiotic efficacy when treating multidrug-resistant bacterial infections.

Study on noise reduction method of main noise transmission path of axial piston pump with new damping material

Axial piston pump is complex fluid machinery with mechanical fluid coupling, and it has the characteristics of multiple noise sources. In order to solve the high noise problem of axial piston pump, this paper proposes a noise reduction method by identifying the main noise sources of axial piston pump and laying new damping materials to reduce noise. It breaks through the existing method of optimizing the parameters of piston pump shell and valve plate structure. A multi-parameter trajectory sensitivity identification and noise reduction method for vibration transmission path of axial piston pump is proposed in this paper. First, the lumped parameter method is used to establish the mathematical model of vibration transmission path of axial piston pump. The sensitivity of structural vibration response to transmission path multi-parameters are analyzed based on trajectory sensitivity method. The most sensitive parameters in the main noise transmission path are determined. Then, the experimental study of radiated noise transmission path of axial piston pump is carried out. A new type of viscous damping material is proposed to reduce the noise on the transmission path of the main noise source. The experimental results show that the noise of piston pump is reduced by 2.32 dB. The research results provide a new method and way for the design and manufacture of low noise piston pump.

Transient trend prediction of safety parameters for small modular reactor considering equipment degradation

Small modular reactor (SMR) has strong coupling characteristics and complex nonlinearities. Predicting the trend of SMR safety parameters and monitoring whether the parameter values exceed operational limits and conditions (OLC) before performing a transient helps the operator to judge the safety of the transient, especially in the case of equipment degradation. In this paper, a transient trend prediction method of SMR safety parameters based on random forest model was proposed, which considered the impact of equipment degradation on safety parameters. The transient data used for model training included different load-following conditions considering various degraded degrees of rotating speed drop in the main coolant pump (MCP) or effective heat transfer area reduction in the once-through steam generator (OTSG). To evaluate the model, the new untrained transient data was used as test data, the results showed that safety parameters were more accurately predicted by random forest, compared with the backpropagation neural network.