Flow Sodium Research Articles

IL-1 receptor antagonist anakinra downregulates inflammatory cytokines during renal normothermic machine perfusion: Preliminary results.

The interleukin 1 (IL-1) cytokine group plays a key role in sterile inflammation and may be an important target for transplant-related renal injury. This study examined the effects of anakinra, a non-specific IL-1 receptor antagonist, administered during normothermic machine perfusion (NMP) of porcine kidneys. Paired porcine kidneys (n = 5 pairs) underwent 15 min of warm ischemia plus 2 h of static cold storage in ice. Kidneys were then perfused with autologous whole blood using an exvivo NMP platform. Kidneys were randomly allocated to receive anakinra or vehicle administered at the start of NMP. Cortical biopsies were collected at baseline before ischemic injury and at the end of NMP. Functional parameters were recorded and calculated, and inflammatory markers were measured by qPCR and ELISA techniques. During NMP, there were no statistically significant differences in renal blood flow, urine output, creatinine clearance or fractional excretion of sodium in the anakinra and control groups. The administration of anakinra significantly downregulated transcriptional expression of IL-6, Fas ligand and intercellular adhesion molecule 1 (p = 0.029, 0.029, 0.028, respectively). Anakinra, an IL-1 receptor blocker, successfully attenuated the downstream inflammatory and immune-mediated response within the kidney during NMP.

Direct numerical simulation of sodium in vertical channel flow: From forced convection to natural convection at friction Reynolds number 180

The buoyancy-aided sodium flow in a vertical channel is investigated using direct numerical simulation (DNS) to study turbulent flow and heat transfer at six different Richardson numbers (Ri = 0, Ri = 0.025, Ri = 0.25, Ri = 2.5, Ri = 7.5, and Ri = 15) with a fixed friction Reynolds number (Reτ = 180). The results reveal that the velocity profile shows an “M” shape under buoyancy effect and reverses at the center under strong buoyancy. Additionally, the temperature profile exhibits a thicker boundary layer compared to the velocity profile. Global coefficients, such as the skin friction coefficient and the Nusselt number, are analyzed using Fukagata, Iwamoto, and Kasai (FIK) decomposition to elucidate their respective contributions. Furthermore, anisotropy analysis indicates that buoyancy makes the turbulence more isotropic, and the buoyancy also makes the turbulent Prandtl number (Prt) unpredictable; however, a comparison among the molecular heat flux, the definition of turbulent heat flux, and the calculation of the standard gradient diffusion hypothesis (SGDH) model suggests that the turbulent heat flux can be neglected without significant influence in this study. Finally, the turbulent structures in the viscous layer are presented, and the quadrant analysis is performed to quantitatively analyze the influence of buoyancy on the turbulent structure.

Thermo-structural analysis of a dump nozzle for conducting hot liquid sodium

Liquid sodium is found to be an essential element in nuclear reactors for transferring enormous amount of heat between source and sink. Conducting hot liquid sodium through metal pipes is witnessed to be challenging owing to the huge thermomechanical stress involved during the process. The present research work aims at designing a dump nozzle for the safe transfer of hot liquid sodium (at 923 K) to a storage tank through SS316LN pipe. Numerically simulated results showed the development of huge thermal stress at the weld junction formed between pipes and storage tank, which is primarily due to the sudden increase in temperature. The newly proposed dump nozzle with reducer/baffle (connecting pipe with storage tank) is witnessed in reducing the sudden increase in temperature and henceforth, minimized the stress intensity of the weldment by 70 %. The fatigue-creep interaction diagrams are plotted for the weld and the reducer; the results showed that the induced stress values for the parts are well below the safety envelops for the given boundary conditions of liquid sodium flow velocity and temperature. The proposed dump nozzle design is hence validated for the safe handling of transferring liquid sodium to storage tank.

Numerical simulation of fluid dynamics and mixing in headers of sodium-air heat exchangers

The paper presents the results of a numerical simulation for sodium fluid dynamics and mixing in the tubing system of an air-cooled heat exchanger (AHX), which is a part of the emergency cooldown system (ECS) of sodium fast reactors (SFRs). Non-uniform sodium flows in the AHX tubing system may lead to the mixing of different-temperature sodium flows, temperature fluctuations and tube breaks. It was found in the course of investigating accidents involving breaks in the PFR and Phénix reactor AHX tubing systems that the failure was caused by the metal temperature fluctuations (Cruickshank and Judd 2005). The numerical simulation used three- and one-dimensional computer codes. It has been found that the calculations of the AHX sodium flow rate distribution with a practically acceptable accuracy can be performed using a one-dimensional code. The factors that influence the non-uniform distribution of sodium flows in the AHX tubing system have been analyzed. Calculations have been performed for the AHX sodium flow distributions and for the mixing of different-temperature sodium flows in the AHX outlet header. The results are presented from calculating the amplitude of sodium fluctuations near the AHX header walls. The effect from shutting down several modules on the non-uniform flow distribution and temperature fluctuations in the AHX has been investigated. Approximations of numerical solutions have been obtained for the sodium flow distribution as a function of the number of the modules shut down.

Study of antiarrhythmic activity 2-(n-butylpyrrolidine)-N-(2-bromophenyl)carboxamide hydrochloride

Objective. To study the efficacy of a new derivative 2-(alkylpyrrolidine)-N-(aryl)carboxamide with high antiarrhythmic activity. Materials and methods. To study the antiarrhythmic activity of the compound, the experiment was carried out on models of arrhythmia caused by intravenous administration of aconitine and adrenaline. The effect was estimated by its ability to prevent the onset of arrhythmia, prolong the survival time of the animals or by the duration of an arrhythmia attack. In addition, the electrocardiogram of awake rats was analyzed. The studied compound and the comparison drug (lidocaine) were injected to the animals intravenously in effective antiarrhythmic doses. Results. In aconitine arrhythmia 2-(n-butylpyrrolidine)-N-(2-bromophenyl) carboxamide hydrochloride provides statistically significant limitation of the duration of arrhythmia attacks in experimental animals (1.7 times) in comparison with the control and also reduction of arrhythmia duration in comparison with lidocaine (2.5 times); besides, this compound guarantees animals’ survival in 100 % of cases. When causing arrhythmia by adrenaline administration, the compound does not prevent the occurrence of cardiac rhythm disorder. The electrocardiogram readings of animals do not change significantly. Conclusions. 2-(n-butylpyrrolidine)-N-(2-bromophenyl) carboxamide hydrochloride (compound K-23) shows visible activity in models of arrhythmia caused by administration of aconitine and calcium chloride, which may indicate its ability to impede the sodium flow through the cell membrane by slowing depolarization of cardiomyocytes. Since the compound studied, demonstrates high antiarrhythmic activity without changing the ECG readings, the drug created on its basis may be effective.

Numerical simulation of thermal mixing of liquid sodium in a Y-junction

Numerical simulations are conducted to investigate the flow and heat transfer behaviour of liquid sodium in a Y-junction. Three thermal hydraulic parameters – the fluid momentum ratio, the temperature difference between the inlets of the two branches, and the inlet Reynolds number – are studied to understand their impact on flow development, mixing characteristics, and heat transfer in the main pipe. Results indicate that the momentum ratio is a key factor affecting flow development and temperature distribution. When the momentum ratio lies outside a certain range, flow impingement on the opposite wall occurs. If the ratio falls within this range, two jet flows merge into a turn/deflecting slab-shaped jet, accompanied by two pairs of counter-rotating vortices in the main pipe. The Reynolds number has a negligible impact on flow and thermal mixing patterns for the turbulent flows considered. However, lower Reynolds numbers result in stronger velocity variation and weaker temperature differences at the cross-section in the mixing area. Lastly, the inlet temperature difference has a very limited impact on flow and thermal mixing, and changes in physical property variables negligibly affect velocity and temperature distributions in flow and thermal mixing.

Investigation of key parameters for the operation of a sodium heat pipe with visualization using X-ray radiography

Alkali metal heat pipes are considered as a promising primary cooling system of special-purpose nuclear reactors. For the deployment, it is important to understand the heat pipe’s behaviors under different operation conditions. In this paper, the startup characteristics and operation performance of three sodium heat pipes with 67%, 102% and 172% sodium filling ratios, respectively, were investigated, and the two-phase sodium flow was visualized using high-speed, high-resolution x-ray radiography. The boiling flow regimes in the evaporator region were categorized into stagnant sodium liquid pool, geyser boiling and developed boiling. The effect of key parameters, such as the boundary conditions of the evaporator and condenser, the sodium filling ratio, and the inclination angle were investigated. It was found that the heater power and condenser cooling conditions have a great influence on the operation temperature within the achievable range of heat transfer rate. The filling ratio and inclination angle affect the boiling phenomena and the heat pipe operational range. The experiments can provide valuable data for heat pipe model validation as well as the design of the special-purpose nuclear reactor and other high-temperature heat pipe systems.

Design and Analyses of Miniature, Submersible Annular Linear Induction Pump for Test Loops Supporting Development of Advanced Nuclear Reactors

A submersible annular linear induction pump (ALIP) design with an outer diameter of 66.8 mm with appropriate materials is developed for circulating molten lead and alkali liquid metals of sodium and sodium-potassium-78 (NaK-78) alloy in test loops at temperatures up to 500°C. These loops investigate the compatibility of these liquid coolants with nuclear fuel and structure materials to support the development of advanced, Generation IV nuclear reactors. The present ALIP, which employs high-temperature ceramic-insulated coil wires and Hiperco-50 center core and stators, fits in Type 316 stainless steel, 2.5-in. standard schedule 5 pipe. This pipe, considered for the riser tube of the Versatile Test Reactor (VTR) in-pile test cartridge loop, has an inner diameter of 68.8 mm permitting 1.0-mm radial clearance for the present ALIP. An improved equivalent circuit model (ECM) is developed to analyze the performance of the present ALIP design. The accuracy of the model predictions is successfully validated using reported experimental measurements by other investigators for a low liquid sodium flow ALIP at 200°C and 330°C. The improved ECM calculates the performance characteristics of the present ALIP design and investigates the effects of varying the terminal voltage, current frequency, winding wire diameter, center core length, width of the liquid flow annulus, and working fluid properties and temperature on the pump operation. For circulating molten lead, the calculated peak efficiency of the present ALIP design of 6.7% occurs at a flow rate of 9.5 kg/s and pumping pressure of 263 kPa. The calculated peak efficiency for circulating liquid sodium is much higher, 26.3%, and occurs at a lower flow rate of 2.2 kg/s but a higher pumping pressure of 364 kPa. The calculated peak efficiency for circulating NaK-78 (23%) is lower than for sodium and occurs at a lower flow rate and pumping pressure of 1.9 kg/s and 310 kPa, respectively.

High-Fidelity Simulations of Shield Assembly Mixed-Convection Flows with Applications Toward Reduced-Resolution Modeling

Flow circulation and heat removal through shield and reflector assemblies can have major impacts on safety in long transients for sodium fast reactors (SFRs). These transients are typically categorized by reduced flow rates and large-scale organized flow patterns, including potential intra-assembly circulation. Such low-flow cases can provide challenges for experiments because of complications in measuring the flow rates and temperatures with high accuracy in different areas. This consequently also raises the uncertainty of many modeling approaches for these phenomena. In an effort to address some of these issues, high-fidelity large eddy simulations are performed using the highly parallel solver NekRS. A 19-pin configuration of a tight-lattice wire-wrapped hexagonal bundle (pitch-to-diameter ratio = 1.07), representing a prototypical internal configuration of a shield assembly, was investigated. The sodium flow was set at a bundle Reynolds number of 2000, with simulations being performed for modified Richardson numbers of 0.0 (i.e., no buoyancy), 0.01, and 0.04, where mixed-convection effects are anticipated. The flow and temperature fields for these cases are discussed in detail. The high-fidelity data should prove useful as reference data for expanding and improving on various reduced-resolution approaches. A basic framework for combining subchannel and computational fluid dynamics methodologies in SFRs is also presented, with preliminary results from simulations of light water reactor bundles and a discussion of changes that need to be made for potential application to SFRs.

Abstract P3019: During Salt-sensitive Hypertension, CD8+ T Cells Increase Renal Sodium Transporters, NKCC2 And ENaC

Hypertension originates in part from impaired salt handling by the kidneys. However, the exact identity of this kidney defect remains unknown. As established recently, the adaptive immunity, T cells in particular, acts as an important contributor to the pathogenesis of hypertension. In this regard, our laboratory has reported that CD8+ T cells (CD8Ts) adoptively transferred from salt-sensitive hypertensive mice to normotensive mice stimulate Sodium Chloride Cotransporter (NCC) increasing sodium retention. However, whether other sodium transporters within the nephron are affected by CD8Ts and contribute to this pathogenesis of hypertension remains uncharacterized. We hypothesize CD8Ts will also have an impact on other sodium channels. Through in vivo studies, we employed a CD8T-adoptive transfer model as described in our previous publications. The kidneys from mice receiving adoptive transfer of hypertensive CD8Ts were harvested and protein levels of NKCC, αENaC, βENaC, and γENaC were analyzed by western blot. In vitro, we co-cultured mouse CD8Ts with Collecting Duct epithelial cells (CDs, M1 cells) to examine the direct interaction between CD8Ts and CDs in media containing various levels of corticosteroids. Similar western blots were performed after this co-culture, as well as measurement of sodium retention through an intracellular sodium indicator and flow cytometry, as reported previously. In vivo, we found that the kidneys of mice receiving adoptive transfer of hypertensive CD8Ts demonstrated higher expression of NKCC, βENaC and γENaC, but no change in αENaC. As for in vitro, we further found that in charcoal-stripped co-culture conditions, pre-activated CD8Ts stimulate higher expression of ENaC subunits and ENaC-mediated sodium retention in M1 cells. However, these effects are masked in culture conditions with physiological or with additional corticosteroid levels. Overall, our results suggest that, as a potential kidney defect, hypertensive CD8Ts strongly stimulate NCC and NKCC in the kidney to mediate excessive salt retention and any effect of CD8Ts in increasing ENaC may be masked in physiologic conditions.

Numerical simulation of localization of a sub-assembly with failed fuel pins in the prototype fast breeder reactor

The early localization of a fuel subassembly with a failed (wet rupture) fuel pin is very important in reactors to limit the associated radiological and operational consequences. This requires a fast and reliable system for failure detection and their localization in the core. In the Prototype Fast Breeder Reactor, the system specially designed for this purpose is Failed Fuel Location Modules (FFLM) housed in the control plug region. It identifies a failed sub-assembly by detecting the presence of delayed neutrons in the sodium from a failed sub-assembly. During the commissioning phase of PFBR, it is mandatory to demonstrate the FFLM effectiveness. The paper highlights the engineering and physics design aspects of FFLM and the integrated simulation towards its function demonstration with a source assembly containing a perforated metallic fuel pin. This test pin mimics a MOX pin of 1 cm2 of geometrical defect area. At 10% power and 20% sodium flow rate, the counts rate in the BCCs of FFLM system range from 75 cps to 145 cps depending upon the position of DN source assembly. The model developed for the counts simulation is applicable to both metal and MOX pins with proper values of k-factor and escape coefficient.

Direct Numerical Simulation of Low and Unitary Prandtl Number Fluids in Reactor Downcomer Geometry

Mixed convection of low and unitary Prandtl fluids in a vertical passage is fundamental to passive heat removal in liquid metal and gas-cooled advanced reactor designs. Capturing the influence of buoyancy in flow and heat transfer in engineering analysis is hence a cornerstone to the safety of the next-generation reactor. However, accurate prediction of the mixed convection phenomenon has eluded current turbulence and heat transfer modeling approaches, yet further development and validation of modeling methods is limited by a scarcity of high-fidelity data pertaining to reactor heat transfer. In this work, a series of direct numerical simulations was conducted to investigate the influence of buoyancy on descending flow of liquid sodium, lead, and unitary Prandtl fluid in a differentially heated channel that represents the reactor downcomer region. From time-averaged statistics, flow-opposing/aiding buoyant plumes near the heated/cooled wall distort the mean velocity distribution, which gives rise to promotion/suppression of turbulence intensity and modification of turbulent shear stress and heat flux distribution. Frequency analysis of time series also suggests the existence of large-scale convective and thermal structures rising from the heated wall. As a general trend, fluids of lower Prandtl number were found to be more susceptible to the buoyancy effect due to stronger differential buoyancy across the channel. On the other hand, the effectiveness of convective heat transfer of the three studied fluids showed a distinct trend against the influence of buoyancy. Physical reasoning on observation of the Nusselt number trend is also discussed.

Doxorubicin-Loaded Platelet Decoys for Enhanced Chemoimmunotherapy Against Triple-Negative Breast Cancer in Mice Model.

Triple-negative breast cancer (TNBC) is a highly aggressive subtype with a poor prognosis. Current single-agent checkpoint therapy has limited effectiveness in TNBC patients. In this study, we developed doxorubicin-loaded platelet decoys (PD@Dox) for chemotherapy and induction of tumor immunogenic cell death (ICD). By combining PD-1 antibody, PD@Dox has the potential to enhance tumor therapy through chemoimmunotherapy in vivo. Platelet decoys were prepared using 0.1% Triton X-100 and co-incubated with doxorubicin to obtain PD@Dox. Characterization of PDs and PD@Dox was performed using electron microscopy and flow cytometry. We evaluated the properties of PD@Dox to retain platelets through sodium dodecyl sulfate-polyacrylamide gel electrophoresis, flow cytometry, and thromboelastometry. In vitro experiments assessed drug-loading capacity, release kinetics, and the enhanced antitumor activity of PD@Dox. The mechanism of PD@Dox was investigated through cell viability assays, apoptosis assays, Western blot analysis, and immunofluorescence staining. In vivo studies were performed using a TNBC tumor-bearing mouse model to assess the anticancer effects. Electron microscopic observations confirmed that platelet decoys and PD@Dox exhibited a round shape similar to normal platelets. Platelet decoys demonstrated superior drug uptake and loading capacity compared to platelets. Importantly, PD@Dox retained the ability to recognize and bind tumor cells. The released doxorubicin induced ICD, resulting in the release of tumor antigens and damage-related molecular patterns that recruit dendritic cells and activate antitumor immunity. Notably, the combination of PD@Dox and immune checkpoint blockade therapy using PD-1 antibody achieved significant therapeutic efficacy by blocking tumor immune escape and promoting ICD-induced T cell activation. Our results suggest that PD@Dox, in combination with immune checkpoint blockade therapy, holds promise as a potential strategy for TNBC treatment.

Development of a statistical evaluation method for core hot spot temperature in sodium-cooled fast reactor under natural circulation conditions

To enhance the safety of a sodium-cooled fast reactor (SFR), natural circulation must be able to remove the decay heat in the core, even if the AC power supply to the forced circulation equipment is lost. Under natural circulation conditions, deterministically evaluating the core hotspot temperature considering the effects of uncertainty on the sodium flow and heat is difficult because the flow is driven by buoyancy, and the flow rate and the temperature distribution influence each other. This study develops a statistical evaluation method for the core hot spot temperature by propagating the uncertainty through the input of the analysis to the output using the Monte Carlo sampling method. The core hot spot evaluation method is applied to three representative events during the natural circulation decay heat removal operations in a loop-type SFR.

Numerical studies on liquid sodium flow boiling in a 7-pin hexagonal subassembly towards flow rundown scenario in SFR

The present study is intended for the development of high resolution CFD based model for the prediction of two-phase flow and heat transfer characteristics of liquid sodium in a 7-pin bundle. The sodium flow boiling from its inception to nucleate boiling and the forced convective vaporization regimes are analyzed by developing an Eulerian-Eulerian model (two-fluid model) using flow regime dependent constitutive correlations and modified non-equilibrium wall boiling model. The Algebraic Interfacial Area Density (AIAD) model is implemented for providing required closure terms as flow regime dependent based on the local flow topology within the two-fluid model. The sodium flow boiling simulations are performed in a 7-pin subassembly using the model under constant wall heat flux for different inlet mass flow rates and predicted the quasi-steady boiling. The radial and axial void fraction progress in the flow sub-channels, variation of sodium temperature, and wall boiling components along the heated pin length are numerically predicted. Also analyzed the transient sodium boiling under flow rundown scenario in the 7-pin subassembly with a continuous reduction in the inlet mass flow rate under constant wall heat flux. The prediction of wall temperature variation during this flow scenario confirmed the incidence of local dry-out at the end of the transient which causes loss of heat transfer from the pin surface. Also, the mechanistic model based evaluations for wall heat transfer coefficient and possible flow regimes are obtained based on the flow and thermal conditions predicted.

CD8+ T cells stimulate renal sodium transporters contributing to salt-sensitive hypertension

Impaired salt handling by the kidneys acts as one source of hypertension. However, the exact identity of this kidney defect remains unknown. As established recently, the adaptive immunity, T cells in particular, acts as an important contributor to the pathogenesis of hypertension. In this regard, our laboratory has reported that CD8+ T cells (CD8Ts), when adoptively transferred from salt-sensitive hypertensive mice to normotensive mice, stimulate Sodium Chloride Cotransporter (NCC). Through this stimulation, sodium retention occurs, and salt-sensitive hypertension develops. However, whether other sodium transporters within the nephron are affected by hypertensive CD8Ts and contribute to this pathogenesis of hypertension remains uncharacterized. We hypothesize hypertensive CD8Ts will also have an impact on other sodium channels. Here, we demonstrate the impact of hypertensive CD8Ts on sodium-potassium-co-transporter (NKCC) and epithelial sodium channel (ENaCs) in the kidney and the potential of these regulations contributing to salt-sensitive hypertension.Through in vivo studies, we employed a CD8T-adoptive transfer model as described in our previous publications. The kidneys from mice receiving adoptive transfer of hypertensive CD8Ts were harvested and protein levels of NKCC, αENaC, βENaC, and γENaC were analyzed by western blot. With in vitro studies, we co-cultured mouse CD8Ts with Collecting Duct epithelial cells (CDs, M1 cells) to examine the direct interaction between CD8Ts and CDs in media containing various levels of corticosteroids. Similar western blots were performed after this co-culture, as well as measurement of sodium retention through an intracellular sodium indicator and flow cytometry, as reported previously.In the results of in vivo studies, we found that the kidneys of mice receiving adoptive transfer of hypertensive CD8Ts demonstrated higher expression of NKCC, βENaC and γENaC, but no change in αENaC. In the results from in vitro studies, we further found that in charcoal-stripped co-culture conditions, pre-activated CD8Ts stimulate higher expression of ENaC subunits and ENaC-mediated sodium retention in M1 cells. However, these effects are masked in culture conditions with physiological hormone levels or with additional corticosteroids.Overall, our results suggest that, as a potential kidney defect, hypertensive CD8Ts strongly stimulate NCC and NKCC in the kidney to mediate excessive salt retention. Although CD8Ts themselves can increase ENaC, this effect might be masked in physiologic conditions. NIH R01-HL146713 (Mu), AHA 15BGIA25730047 (Mu), and SPaT T32-GM10699 (Deck) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Mixing of Different Temperature Flows of Liquid Sodium in the Pipeline behind the Tee

Mixing of Different Temperature Flows of Liquid Sodium in the Pipeline behind the Tee

Optimization of chemical oxygen demand removal from petroleum refinery wastewater by electrocoagulation using tubular electrochemical reactor with a novel design

In this study, removal of chemical oxygen demand (COD) from petroleum refinery effluent was investigated using a new tubular electrochemical reactor (TER) design which operated at a batch recycle model. The electrochemical reactor comprises of two concentric electrodes namely spiral aluminum rode anode and hollow cylindrical stainless steel cathode. Four parameters were investigated: current density, sodium chloride concentration (NaCl), pH, and flow rate on the COD removal efficiency, and optimized using response surface methodology. Results show that current density is the most influential parameter on removal percentage where increasing current density results in increasing the removal efficiency. Another effect of lowering flow rate resulted in high removal of COD due to the increased resistance time of effluent passing on the surface of the anode with the newly adopted design. Finding of laboratory work were obtained under optimal working conditions such as current density of 26 mA/cm2, pH of 7.9, NaCl concentration of 1.1 g/L, and flow rate of 2 L/min. These were resulting in a COD removal efficiency of 73.36% with specific energy consumption of 30.61 kWh/kg·COD. Operating cost of the present system was found to be $2.185 m3 which is considered low and acceptable. Experimental results prove that the new design of TER is more efficient than the traditional design that uses in electrocoagulation system to treat wastewater generated from petroleum refinery plants.

Signal Modeling of Permanent Magnet Sodium Flowmeter With Embedded Vortex Generator Based on Transit Time Series

The permanent magnet sodium flowmeter with embedded vortex generator (PMSF-VG) monitors the liquid metal sodium flow rate in real time in order to ensure the safe operation of the fast neutron reactor. The previous literature studied how to improve the in-situ calibration accuracy of the flowmeter from the perspective of signal processing. This paper studies this issue from the perspective of signal source. According to the experimental data, the transit time series is calculated by using the generalized cross-correlation method, its characteristics are analyzed, and a moving average (MA) model is established for predicting and improving the accuracy of the in-situ calibration. This model is composed of a steady-state component and a fluctuation component. The former reflects the ideal value of the cross-correlation flow rate in the in-situ calibration, and is related to the meter linearity and indication error, which determines the upper limit of the measurement accuracy. The latter determines the repeatability error of the in-situ calibration. Aiming at its feature, a two-stage moving average filtering method is adopted to reduce the repeatability error of measuring the transit time and improve the accuracy of the in-situ calibration.

A New Proposal Generalized Predictive Control Algorithm With Polynomial Reference Tracking Applied for Sodium Fast Reactors

This paper proposes a generalized predictive control (GPC) with constraints and orthonormal Laguerre functions using the simplified model of the primary system (reactor core and intermediate heat exchanger (IHX)) of a prototypical sodium fast reactor (SFR). This paper develops a multiple-input multiple-output (MIMO) GPC with input constraints able to track polynomial references of any degree applied in coolant temperature difference across the core and fractional power. The manipulated variables of the GPC-SFR are the reactivity and the sodium flow rate of the primary and secondary pipes. Moreover, orthonormal Laguerre functions and step down condition number techniques were also applied to avoid the numerical ill-conditioning issue in quadratic programming of large systems. Thus, a GPC type-2 was designed to control fractional power, coolant temperature difference across the core and sodium tank temperature of the SFR primary system when temperature references change according to a linear ramp after reaching their steady-state operation, sustaining 100% power operation on the reactor. In order to analyze the load tracking capability of the GPC-SFR type-2, the load following from 100% fractional power (FP) to 60% FP at 0.8% FP/min rate is simulated. Constraints on the rate of coolant temperature difference across the core and reactivity were applied for the design safety. For comparison criteria, this paper compares the GPC-SFR type-2 with the GPC-SFR type-1, i.e, standard model predictive control (MPC), to verify the viability and superior performance of the proposal regarding: (a) ramp-tracking capability of temperature and load; (b) the rejections of a reactivity disturbance of -1 cent and a secondary sodium inlet temperature disturbance of +10°F; and (c) a simulation with uncertainty in reactor design. The simulations show that the GPC-SFR type-2 overcome the GPC-SFR type-1 robustness and performance.