Primary Pump Research Articles

Investigation on the hydraulic process of inertia tank in the case of pump trips

The inertia tank (IT) used in the deep pool-type nuclear reactor (DPR) is a novel design to reduce the decrease rate of core flow in the early stage of loss of flow accident. Under the action of IT, the reactor can be safely reduced to low power conditions. In this paper, based on cold state condition, the hydraulic process of IT is studied by experiment. Furthermore, RELAP5 is used to simulate hydraulic process of IT and the results show that RELAP5 can well simulate the variation of water level and mass flow during the working process of IT. The maximum relative error of water level and mass flow are 0.5% and 5.6%, respectively. Based on the RELAP5 model, the influences of flow resistance on the hydraulic process of IT are studied. The research results show that the hydraulic process of IT is significantly affected by the flow resistance in both upstream part of IT (UIT) and connection pipe (CP), while the flow resistance in downstream part of IT (DIT) has little effect on the hydraulic process of IT. In addition, the differences between IT and primary pump with flywheel are compared by the means of RELAP5. The research in this work can provide reference for the design of IT.

Variable importance for chiller system optimization and sustainability

Very few studies have considered modelling the statuses of loading and component combinations (LC) in chiller systems. This study uses a decision tree (DT) and a neural network (NN) to model accurately six output levels of LC in terms of 11 predictor variables. The NN model gave a higher correct prediction of 89.52% than 84.44% in the DT model. A variable dropout analysis from the DT and NN models generalizes the top five significant variables: the statuses of cooling towers and primary chilled water pumps, and the supply temperature, return temperature and flow rate of chilled water. The system coefficient of performance (SCOP) modelled by NN has an improved R 2 of 84.18% versus 74.62% when the significant variables are included as inputs. The SCOP maximization brings three optimal strategies—implementing chiller sequencing, operating components in pairs and optimizing chilled water supply temperature—which reduce CO2 emissions by 99,815–346,987 kg.

Calculation and Analysis of Critical Heat Flux at LWR Passive Safety Design

Critical heat flux (MDNBR) is one parameter for safe nuclear reactor operation. The magnitude of MDNBR is determined by local heat flux. When it is sufficiently high, it will cause a change in heat equilibrium and deteriorate nuclear fuel structure. To obtain assurance for nuclear reactor safety in safe criteria, Calculation and analysis of Critical heat flux of 630 MWe passive LWR was carried out at steady state and transient condition. The study used COBRA IV-I sub channel program coupled with critical heat flux correlation of EPRI-Columbia and W-3. The program models the core into 1/8 sections, each of which is divided into 83 sub-channels in radial direction and 40 nodes in axial direction, including 8 sub-channels of the hottest assembly. Normalized coast down flow and reactor power decay at initial phase is 10 second after loss of flow accident (LOFA) caused by anticipated primary pump failure. The effects of all input parameters, such as radial nodes, axial nodes, mix coefficient, velocity of coolant mass entering the core and power variation, have been identified. Evaluation of the results of safety calculation indicates that MDNBR, cladding temperature, and hot channel temperature are 1.83, 349°C and 2033°C, respectively. As the licensing limits for those parameters are 1.3, 1850°C, and 2840°C, it is concluded that the design of 630 MWe passive LWR has met the licensing criteria of safety. Modelling for safety analysis of passive LWR employs COBRA IV-I program. The results show that this program can be used to calculate hydraulic safety parameters with sub-channel model.

Numerical analysis of liquid fall type gas entrainment in pool-type fast reactor

Argon covering the free surface of the pool-type sodium-cooled fast reactor may be mixed into the coolant in form of entrainment bubbles due to the fluctuation of liquid surface, which introduces positive reactivity to the core, reduces the heat exchange capacity of the core and intermediate heat exchangers (IHXs), and possibly leads to the cavitation of the primary sodium pump (PSP), threatening the safe operation of the reactor. In this study, the computational fluid dynamics (CFD) simulation of liquid sodium fall entrained argon was carried out based on the Volume of Fluid (VOF) interface tracking method to describe the entrainment process in detail, and the influences of geometry size, initial liquid level height and inlet velocity on entrainment were analyzed successively. It was found that the re-submergence velocity, having a linear relation with the re-submergence angle, is the key factor of the liquid fall type gas entrainment. It can be used to judge whether the liquid fall type entrainment occurs conservatively. In addition, the parameters affecting the re-submergence velocity are specifically analyzed from the supplementary cases, according to the results of which, the empirical relation of the re-submergence velocity is obtained. Therefore, the situation of liquid fall type gas entrainment under various working conditions can be predicted numerically.

Natural Convection Flapper Valve Design for the Bandung Research Reactor Conversion

National Nuclear Energy Agency has planned to convert the Bandung TRIGA reactor by replacing the rod-type into plate-type fuel elements. The calculation results show that Bandung TRIGA Plate reactor with 2000 kW power requires forced convection cooling system. According to the calculation results using the Coolod-N2 computer program the minimum required cooling flow rate is 70 kg/s. Consequently, it is necessary to modify the reactor primary cooling system. In this modification required a flapper valve design that can a double function. The valve closed when the primary pump is powered and the flow rate on the primary coolant is 70 kg/s. However, when the pump is off because of the power outages and the reactor will scram, so the flapper valve will open. The residual heat in the reactor core will be cooled by natural convection. There is reversal flow from a downward to an upward cooling direction, and the upward natural convection heat removal throughout the flapper valve. In addition, the reactor also will scram if the cooling flow rate drops below 85% of 70 kg/s. The flapper valve is equipped with a ballast pendulum to open the flapper valve. The pendulum load must be greater than the flapper valve force plus the pump force due to forced flow. The flapper valve will open, if the flow rate is smaller than 85% of the required flow. Conversely, the flapper valve load must be smaller than the amount of flapper valve force and flow due to the pumps attractiveness, so that the flapper valve can be closed tightly and the reactor can operate with a forced convection flow. The design of natural convection flapper valve considers the following of a reliable, a work based on passive systems, a simple, an easy to make, an easy maintenance and it can be observed from the top of the reactor tank deck. As a redundancy, the operation of natural convection a flapper valve is added by mechanical operation, so the operation of the valve is truly reliable.

Anomalous characteristics of nanostructured hydrogenated carbon thin films

Hydrogenated diamond-like carbon (DLC) films are sought for several technological applications including electronics, optics, mechanics, and tribology. However, conventional hydrogenated DLC films, that commonly deposit at low base pressure (~10−5 to 10−8 Torr), have many intrinsic limitations in terms of moderate hardness (15–25 GPa), low electrical conductivity (in insulating regime), and they display amorphous morphology. Here we develop high-performance hydrogenated carbon-based films using a cost-effective and fast deposition approach. We report the room temperature synthesis of nitrogen incorporated nanostructured hydrogenated carbon films (n-C:N:H) at a high base pressure of ~5 × 10−3 Torr, employing a non-conventional radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) system equipped with only a primary pump. The n-C:N:H films show appealing properties such as wide band gap (2.35–2.9 eV), high optical transparency, high hardness (up to ~ 40 GPa), ultrahigh elasticity (elastic recovery ~95%), reasonably good electrical conductivity, and diode-like behavior when examined in n-C:N:H/Si heterojunction device configuration. Interestingly, some of n-C:N:H films revealed the multifunctional activities with properties surpassing to those of many low base pressure grown traditional amorphous DLC films. This discovery solves many fundamental concerns of hydrogenated DLC films and opens new paths for their enhanced commercial applications.

Molecular strain in the active/deactive-transition modulates domain coupling in respiratory complex I

Complex I functions as a primary redox-driven proton pump in aerobic respiratory chains, establishing a proton motive force that powers ATP synthesis and active transport. Recent cryo-electron microscopy (cryo-EM) experiments have resolved the mammalian complex I in the biomedically relevant active (A) and deactive (D) states (Zhu et al., 2016; Fiedorczuk et al., 2016; Agip et al., 2018 [1–3]) that could regulate enzyme turnover, but it still remains unclear how the conformational state and activity are linked. We show here how global motion along the A/D transition accumulates molecular strain at specific coupling regions important for both redox chemistry and proton pumping. Our data suggest that the A/D motion modulates force propagation pathways between the substrate-binding site and the proton pumping machinery that could alter electrostatic and conformational coupling across large distances. Our findings provide a molecular basis to understand how global protein dynamics can modulate the biological activity of large molecular complexes.

Theoretical research on the characteristics of BOTDR with Raman amplification

Raman amplification is considered as an effective approach to prolong the sensing distance based on Brillouin optical time domain reflectometer (BOTDR) technology. We theoretically simulate the characteristics of BOTDR with Raman amplification by using the principle of spontaneous Brillouin scattering and the coupled mode theory. The simulation results indicate that Raman amplification can effectively increase the BOTDR sensing distance. The optimal incident Raman pump power is 480 mW for first-order Raman amplification, while the optimal incident primary pump and secondary pump powers are 1200 mW and 5 mW respectively for dual-order Raman amplification. Compared with the first-order Raman amplification, the dual-order Raman amplification method has a flatter probe power distribution, and indirectly optimize the signal-to-noise ratio of the received Stokes light.

Winter Phytoplankton Blooms Northwest of the Luzon Island in the South China Sea: A Review

Phytoplankton as a key element in the marine food chain plays a vital role in marine ecosystems. In the South China Sea, phytoplankton blooms often occur northwest of Luzon Island usually during winter, which may have an important impact on primary productivity and regional biological carbon pump. Located in the East Asian monsoon region, the region northwest of Luzon Island is affected by wind stress, Kuroshio and topography with complex dynamic environment. With comprehensive analysis of domestic and international recent studies on phytoplankton blooms in the region northwest of Luzon Island, it is in order to explore the significant impacts of the environmental conditions including wind, Cagayan river discharge, Kuroshio intrusion, upwelling and currents on the spatio-temporal distribution of phytoplankton blooms. It is concluded that the winter phytoplankton bloom is likely due to upwelling and turbulent mixing generated by the Kuroshio interaction with the topography of the Luzon Island. The Cagayan river discharge also contributes to this occurrence, which is the largest river in the Philippines. But the impact of the river is limited to a few kilometers from its mouth. Moreover, the northward flow west of Luzon Island causes the center of the phytoplankton bloom to move northward. This review outlines the impacts of environmental elements on winter phytoplankton blooms northwest of the Luzon Island, and explores potential formation mechanisms of the blooms. Its spatio-temperal distribution can reveal the changes of marine ecosystem indirectly and is of great significance to marine scientific research. The researches on winter phytoplankton blooms also play a guiding role in red tide disaster prevention, marine environmental protection research, fisheries development, to some degree. The more detailed knowledge of the dynamic mechanisms of phytoplankton bloom phenomena contributes to better understanding of the complex marine biogeochemical process near the Luzon Strait.

A new direction in PWR simplification

A new approach to PWR simplification is presented, in which a compact Reactor Coolant System (RCS) configuration is introduced, particularly suited for a power level in the range of 600 MWe. Customary PWR primary system components are eliminated to achieve this RCS simplification. For example, RCS pressure control through a “self-pressurization” mode, with core exit at saturation temperature with less than 1% steam, allows elimination of a pressurizer. Also, mechanical control rods are replaced by reactivity control using negative moderator void and temperature coefficient together with variable speed primary pumps, and with an upgrade in the safety boration function. Decay heat removal in shutdown conditions is realized through the secondary side rather than through primary side equipment. The compact RCS can be installed in a small volume, high-pressure containment. The containment is divided into two leak-tight zones separated by a partition plate. Safety equipment installed in one of the two zones will be protected against adverse ambient conditions from leaks or breaks in the other zone. The partition facilitates management of coolant inventory within the RCS and the containment following RCS leaks or breaks. In particular, the safety injection system as commonly known, consisting of accumulators and multiple stages of injection pumps can be discarded and replaced by gravity-driven flooding tanks. Space available around major RCS components is adequate to avoid compromising accessibility during maintenance or in-service inspection operations. In addition, the two-zone, high-pressure containment provides extra margins in severe accident mitigation. Finally, the proposed containment has a much smaller size than customary large dry containments in PWR practice and it can be anticipated that Nuclear Island building size will similarly be reduced.

Current problems and future avenues in proteoliposome research.

Membrane proteins (MPs) are the gatekeepers between different biological compartments separated by lipid bilayers. Being receptors, channels, transporters, or primary pumps, they fulfill a wide variety of cellular functions and their importance is reflected in the increasing number of drugs that target MPs. Functional studies of MPs within a native cellular context, however, is difficult due to the innate complexity of the densely packed membranes. Over the past decades, detergent-based extraction and purification of MPs and their reconstitution into lipid mimetic systems has been a very powerful tool to simplify the experimental system. In this review, we focus on proteoliposomes that have become an indispensable experimental system for enzymes with a vectorial function, including many of the here described energy transducing MPs. We first address long standing questions on the difficulty of successful reconstitution and controlled orientation of MPs into liposomes. A special emphasis is given on coreconstitution of several MPs into the same bilayer. Second, we discuss recent progress in the development of fluorescent dyes that offer sensitive detection with high temporal resolution. Finally, we briefly cover the use of giant unilamellar vesicles for the investigation of complex enzymatic cascades, a very promising experimental tool considering our increasing knowledge of the interplay of different cellular components.

Design and hydraulic performance studies on an axial lead‐bismuth pump for GEN‐IV reactors

Lead or lead-alloy-cooled fast reactors (LFRs) have been proved to be the most promising generation IV reactors with high performance in neutron economy, thermal hydraulics and security features. When lead-bismuth eutectic (LBE) is used as coolant for LFR, the primary LBE pump is a key conveying equipment in LFRs, because it pumps liquid LBE to remove decay heat produced by core. The hydraulic performance and coolant flow velocity of LBE coolant pump is of great importance for the safety aspects concerning LFRs. This study aims to design an axial LBE pump firstly based on the theory of planar cascade and streamline method, then establishes three-dimensional model of the axial LBE pump and performs the simulation analysis based on Ansys CFX software to study the impact of design parameters on LBE pump hydraulic performance. The results show that the highest flow velocity occurs at the blade of pump and it increases with the rotating speed, while the pump efficiency and pump head appear up-down tendency as the flow rate increasing. The optimum rotating speed and the corresponding impeller parameters are proposed based on the theoretic and numerical studies. The research work will provide a theoretical basis and referred solution for the design of primary pump small module LFRs.

Annual Energy Consumption Cut-Off with Cooling System Design Parameter Changes in Large Office Buildings

A variety of greenhouse gas reduction scenarios have been proposed around the world to ensure sustainable developments and strengthen the global response to the climate change. To cope with this, it is urgently needed to reduce the amount of energy used for the heating, ventilating, air conditioning, and refrigerating (HVAC&R) systems in large buildings. This study discusses the reduction of cooling energy in large office buildings through the minimization of changes in components and equipment, such as heat source equipment and pumps, changes in the layout and operating methods of chilled water circulation pumps, and changes in the temperatures of chilled and condenser water. To do this, this study targeted an entire cooling system consisting of a hydronic system, a chiller, and a cooling tower, and conducted a quantitative analysis of the energy consumption and of the reduction achieved through a change in the pumping system type in the cooling system and a change in the Korean standard design and temperature of chiller and cooling tower via EnergyPlus simulations. The simulation results showed a cooling energy reduction of 103.2 MWh/yr, around 15.7%, where the primary constant-speed system (Case A) was changed to a primary variable-speed pump (Case B) in the configuration with a chilled water circulation pump. To reduce the cooling energy further, annually 142.3 MWh, around 21.7%, Case C in this study changed the outlet temperature of the chiller and temperature difference from 7 °C, 5 K to 9 °C, 9 K. Finally, when applying a change in the condenser water production temperature from 32 to 23.9 °C in accordance with ASHRAE Standard 90.1 for Case D, a cooling energy saving of 182.4 MWh/yr was observed, which is about 27.8%.

Experimental Vortex Flow Patterns in the Primary and Secondary Pump Intakes of a Model Underground Pumping Station

In order to provide specific references and suggestions for the design and operation of underground pumping stations, in this paper, an experimental model of an underground pumping station, including 4 pumps and 2 pump intakes (primary and secondary), was obtained through similitude of fluid mechanics. The phase diagrams of various vortices, in terms of different dimensionless numbers are presented, which can reveal their appearance and evolution process. Three specific cases with different vortex flows were analyzed. The experiment results may provide a reference for the current design guidelines for underground pumping stations.

Detection of Open Water in the Ice by Phase Contrast from the Board of the Underwater Vehicle

The impulse parametric sonar’s structural scheme for the interfaces detection, recognition and classification by amplitude, phase and frequency features of several echo signals at primary pump, sum and difference frequencies, and second harmonic components is considered. Safety navigation supplying for underwater vessel under the ice cover, ice thickness gauging above the vessel, the patches of ice-free water detection in ice- fields, which is suitable for surfacing etc by means of these equipment are suggested.

Low-power-threshold parametric decay instabilities of powerful microwave beams in toroidal fusion devices

We discuss the experimental conditions responsible for a drastic decrease in the power threshold of parametric decay instabilities under auxiliary electron cyclotron resonance heating (ECRH) in toroidal magnetic fusion devices when the upper hybrid (UH) resonance for the pump wave is absent. We show that for a finite-width pump in the presence of a nonmonotonic (hollow) density profile occurring due to plasma equilibrium in the magnetic islands or anomalous particle fluxes from the ECR layer, 3D localization of one or both daughter waves is possible. This localization leads to the full suppression of daughter wave energy losses from the decay layer and a substantial increase in the nonlinear pumping efficiency. This decreases the power threshold of nonlinear excitation, which can be easily overcome in current ECRH experiments utilizing 1 MW microwave beams. Different scenarios of extraordinary and ordinary wave decays are investigated. The secondary decays of primary daughter waves and pump wave depletion are considered as the most effective mechanisms leading to the transition of primary instability to the saturation regime. The proposed theoretical model was shown to be able to describe the anomalous phenomena discovered in ECRH experiments in different toroidal fusion devices all over the world.

Experimental and numerical investigations on effect of reverse flow on transient from forced circulation to natural circulation

In a sudden shutdown of primary pump or coolant loss accident in a marine nuclear power plant, the primary flow decreases rapidly in a transition process from forced circulation (FC) to natural circulation (NC), and the lower flow enters the steam generator (SG) causing reverse flow in the U-tube. This can significantly compromise the safety of nuclear power plants. Based on the marine natural circulation steam generator (NCSG), an experimental loop is constructed to study the characteristics of reverse flow under middle-temperature and middle-pressure conditions. The transition from FC to NC is simulated experimentally, and the characteristics of SG reverse flow are studied. On this basis, the experimental loop is numerically modeled using RELAP5/MOD3.3 code for system analysis, and the accuracy of the model is verified according to the experimental data. The influence of the flow variation rate on the reverse flow phenomenon and flow distribution is investigated. The experimental and numerical results show that in comparison with the case of adjusting the mass flow discontinuously, the number of reverse flow tubes increases significantly during the transition from FC to NC, and the reverse flow has a more severe impact on the operating characteristics of the SG. With the increase of flow variation rate, the reverse flow is less likely to occur. The mass flow in the reverse flow U-tubes increases at first and then decreases. When the system is approximately stable, the reverse flow is slightly lower than obverse flow in the same U-tube, while the flow in the obverse flow U-tube increases.

FMEA for maintenance criterion at RSG-GAS reactor implemented on JE01-AP01 primary pump

Abstract Reaktor Serba Guna-G.A. Siwabessy (RSG-GAS reactor) is a pool type research reactor, located in Serpong village, Indonesia. For safety of RSG-GAS reactor, the maintenance level criterion of System, Structure and Component (SSC) can be carried out by assessing on occurrence likelihood of a potential risks due to ageing degradation and a Risk Priority Number (RPN) value for assigning maintenance criterion, respectively. The objective of present study is to propose using the Failure Mode and Effects Analysis (FMEA) for assigning the maintenance level criterion of SSC and implementing on JE01-AP01 primary pump within a RSG-GAS reactor. In this research paper, SSC screening and failure based maintenance methodology is identified and classified into suitable classes at radar diagram. Results show that SSC can be prioritized based on failure analysis so that maintenance level criterion for SSC can be determined. On the implemented study, preventive maintenance can be performed to JE01-AP01 primary pump because of its RPN value 270.

Evaluation of the Pump Capability of the Primary Cooling of TRIGA 2000 Research Reactor

The TRIGA 2000 research reactor has been operating since mid 2000. Currently, there are plans to convert the reactor core from cylindrical fuel element to plate type fuel element. The conversion process is expected to not change too many existing systems, including the primary cooling systems. For this reason, it is necessary to evaluate the pump capability of the primary cooling system. Based on experimental studies, then merging with the existing installation system head, it has been obtained the main and the redundant pump mass flow rate of 45 and 45.5 kg/s, respectively. The pump capability decreased by around 5 % compared to the results of its commissioning. If the two pumps are combined in parallel, the combined mass flow rate can increase to 62 kg/s. The existing primary pumps cannot be used for primary cooling system if the reactor core is converted into a plate type, even though both pump are installed in parallel. These results need to be considered in designing a new core of the Bandung TRIGA 2000 research reactor with primary cooling systems that are slightly modified because they have to add the decay tank.

Comparative analysis of key indicators on the basis of processing crude oil of different compositions in the fields

Мұнaй өңдeу өндiрiciндe шикiзaт құрaмының өзгeрiп oтыруы нeгiзгi прoблeмaбoлып тaбылaды. Caпaлы өнiм шығaру мaқcaтындa шикiзaт құрaмынa бaйлaныcты мұнaйөңдeу зaуытының өндiрicтiк қызмeтiн бoлжaу жәнe жocпaрлaу ұcынылaды. Ocы мaқcaттaAқтөбe oблыcындaғы кeн oрындaрдың мұнaйынa жәнe бiрiншiлiк aйдaу бaрыcындa aлынғaнaшық диcтиляттaрғa caлыcтырулaр жacaлды. Әлiбeкмолa жәнe Бозой кeнорындaрыныңмұнaйлaрының нeгiзгi көрсeткiштeрi, яғни зeртхaнaлық жaғдaйдa мұнaй жәнe мұнaйөнiмдeрiнiң сaлыстырмaлы тығыздығы мeн тұтқырлығы aнықтaлды. Компонeнттiкқұрaмы мeн кeнорынның орнaлaсуынa бaйлaнысты мұнaйдың нeгiзгi көрсeткiштeрi әртүрлiболaтындығы aнықтaлды. Бұл көрсeткiштeр мұнaй жәнe мұнaйөнiмдeрiнiң сaпaсынa,қолдaнылу тиiмдiлiгiнe, өңдeу схeмaсын тaңдaудa, тaсымaлдaудa мaңызды болып тaбылaды.Сонымeн қaтaр, өңдeу процeсiн оңтaйлaндыру мeн жұмыс рeжимiн тұрaқты қaдaғaлaуғa,сaпaлы өнiм aлуғa мүмкiндiк бeрeдi.