Bubble detection in sodium flow using EVFM and correlation coefficient calculation

The steam generator (SG) is a heat exchange device between a sodium coolant and water in sodium-cooled fast reactors. Its transfer tubes are prone to leakage to result in sodium-water reaction, which will affect the operational safety of the entire nuclear reactor. To this end, a signal processing method is studied to detect the SG leakage using an electromagnetic vortex flowmeter (EVFM). Water flow is firstly used to replace liquid sodium for conducting the hydraulic experiments, and the output signal of the sensor of the EVFM (abbreviated as EVFM sensor output signal) is collected under different gas injection volumes. The characteristics of the signal are analyzed in the time domain, and the collected signals are modeled. A signal processing method of bubble detection in liquid sodium is proposed based on the peak-to-peak standard deviation, which is realized in real time on the hardware system based on a digital signal processor. The gas injection experiments in liquid sodium are conducted to verify the effectiveness of the signal processing method and system developed in this paper. The minimum amount leakage of water can be detected as 0.1 g/s.

Floor noise based bubble detection method in sodium using EVFM

The oscillating flowmeters have the characteristic fluid flow — oscillation frequency swirled jet. These types of flowmeters are without moving parts, may be on the principle of constructive: the Vortex flowmeters and the Coanda flowmeters. The Vortex flow meters have as basic principle the Vortex accomplishment around obstacles that are placed against the fluid flow. The resulting vibrations are converted into electrical signal through using, in general, piezoelectric sensors. Vortex flowmeters are designed for measuring and counting with high precision liquid flow rates at high speeds and low viscosity. Coanda flowmeters based on the “Coanda effect”, physical phenomenon showing that a free jet of fluid which occurs in a nozzles or pipes, tends to track the nearest surface, attached to it. The experimental study was done on the structure of a flowmeter with “Coanda effect” and acceleration transducer, which transforms frequency oscillations in electrical signal proportional to the amount of liquid flow.

Modeling and simulation of feedwater control system with multiple once-through steam generators in a sodium-cooled fast reactor (II): Control system simulation

In Fast Breeder Reactors (FBR) which are sodium cooled, the steam generator (SG) heat exchanger tubes separate the low pressure sodium flowing in the SG vessel with the high pressure water-steam in tubes. During In-Service Inspection (ISI), sodium is first drained and then SG tubes are cooled down to the room temperature. After sodium draining, due to the high temperature (more than 500 °C), sodium adheres to SG tubes and structures around (SG support plates, welds) in a thin layer, filling eventually the gaps between SG support plates and tubes. During ISI, SG tubes are inspected for cracks and corrosions using differential eddy currents (EC) probes. Due to the high electrical conductivity of sodium adhering to the outer SG tube surface, the eddy current testing (ECT) signal modifies, in accord with sodium layer thickness or sodium deposits located on the outer SG tube surface. The sodium wetting properties depends on several factors as: material surface, temperature and sodium wetting time. The effect of sodium adhering to the outer SG tube on ECT signals were measured using a small mock-up tank (2 m high and 0.7 m in diameter) in which were introduced two SG tubes similar with the ones used in the Monju FBR (one tube is ferromagnetic and made of 2.25Cr–1Mo alloy, while the other one is made of SUS321 and is austenitic). Defects, SG support plates (on both helical and straight part of the tube) and welds were added to tubes and the ECT signal was measured before and after sodium draining. Variations in the sodium layer thickness and consequently its effect on ECT signals were measured by filling and draining the tank three times in order to recreate each time new layers of sodium. The paper describes the experimental conditions and the ECT results for both types of SG tubes by comparing the defects, SG support plates and weld signals before and after draining of sodium. Additionally, sodium structures were examined visually using a VideoScope camera, confirming the recorded ECT signals. The paper also presents details about sodium layer thickness measurements in several parts of SG tubes (near defect, SP, weld, bend, helical tube, straight tube) by scratching and collecting the sodium on a small area of 20mm×20mm. The volume of sodium drops is also estimated. The measurement results showed that there are significant differences in the sodium layer thickness depending on the SG tube material.

Wet gas is commonly encountered in various industries, including energy, chemical, and electric power sectors. For example, natural gas extracted from production often contains small amounts of liquid, such as water and hydrocarbon condensates, which classifies it as wet gas. The presence of liquid within the gas poses challenges for accurate flow measurement. To improve the performances of wet gas flow metering methods, significant research and development efforts have been invested into the wet gas flow metering technologies due to their vital importance in the production, transfer, and trade benefits.This paper presents a comprehensive overview of the recent development of wet gas flow metering. Firstly, a comprehensive discussion of the Lockhart-Martinelli parameter (Xlm) and its relation to the gas void fraction (αg) is presented, which was mostly overlooked in previous wet gas research work. The occurrence of various flow patterns in wet gas conditions at different orientations (horizontal and vertical) was explored. Following an investigation of pressure impact on the wet gas flow patterns and development of the wet gas regions, a different test matrix for further research work was suggested. After a novel classification of wet gas measurement methods, the paper offers a detailed comparison of differential pressure (DP) meters including Venturi, Cone meter, and orifice meters, by considering both liquid and gas flow rate measurements. Secondly, the paper discusses and compares vortex flow meters, Coriolis and ultrasonic meters in comparison to DP meters. Notable phase fraction meters are also examined and compared to one another. Thirdly, the paper reviewed the concept of existing and potential hybrid wet gas meters, conducting a detailed discussion and comparison with commercial solutions by evaluating their ranges and accuracies. This assessment provides valuable insights into the capabilities of these hybrid meters, highlighting their potential to enhance the measurement of wet gas flow rates.

A novel and compact optical vortex flow meter is presented and experimentally demonstrated. The proposed structure can monitor the open area liquid flow velocity based on the von Karman vortex street and floating fibre ring vortex sensor. The optical fibre ring with floating foam sphere is attached behind a bluff body to measure the vortex shedding frequency in the liquid flow. This structure of flow meter occupies less area in the liquid channel, owing to very low consumption of the optical power loss of the sensor head, the flow meter is high power efficiency. Experimental results verify the new technique and demonstrate a vortex water flow meter at room temperature based on the fibre bending ring sensor is sensitive to liquid flow change.

Aiming at the spatial registration problem for networking of multi-platform shipborne radars, a modified maximum likelihood (MML) absolute registration algorithm based on singular value decomposition (SVD) is proposed. Firstly, the four major biases (radar detection biases, platform positioning biases, attitude biases, and baseline conversion biases) which affect shipborne radar detection are analyzed, and an equivalent model of shipborne radar detection biases is established to make the bias parameters more efficiently. Secondly, the maximum likelihood registration method is improved. According to the singular value decomposition, the conditional index is used to evaluate the observability in the maximum likelihood registration method in realtime, and the abnormal conditional index is corrected to effectively reduce the fluctuation of the bias estimation. Finally, the simulation results of two different scenarios are conducted, and the results show that the new method has significant improvements in estimation accuracy and algorithm stability compared with the existing algorithms.

Comparison of pressure and ultrasound measurements in vortex flow meters

Vehicle fuel consumption measurement using carbon balance method based on VMAS was introduced. The influencing factors of fuel consumption measuring result, including gas concentration measurement, flux measurement, quality of fuel, equipment synchrony and vehicle condition, were analyzed according to the measure theory and structure of measuring system. Analysis of the errors caused by these influencing factors was performed based on the field experimental data obtained under steady test condition. The experiment shows that (1) precision of carbon dioxide sensor and oxygen sensor need to be improved; (2) ultrasonic vortex flow meter cannot satisfy the requirement of the fuel consumption measuring system; (3) equipment synchrony of measuring system has little influence on measuring result under steady condition. The problems of the measuring system which need to be solved were pointed out for improving the fuel consumption measuring precision.

Steam is mostly utilized as a means for thermal energy supply in industrial fields. It is important to be aware of the steam flow rate in the view point of energy management. However, steam becomes wet in many cases in the process to be sent through steam pipes to machinery using steam. It is well known that the wetness of steam sometimes causes measurement errors of the steam flow rate, and there has scarcely been the established method for estimating the error caused by the wetness of steam flow. Accordingly, we conducted the flow rate measurement of wet steam whose wetness was between 15 % and 40 % using a vortex flow meter, to clarify the measurement error caused by the wetness of steam, following our previous paper whose wetness was less than 15 %. The experiments were conducted with the conditions in changing the flow rate, pressure and wetness. As a result, the correlation between the measurement error and the flow condition was clarified.

Four-sensor droplet capable conductivity probe for measurement of churn-turbulent to annular transition flow

Development of sputter ion pump based SG leak detection system for Fast Breeder Test Reactor

This paper attempts to describe the worst case error budget and analysis of a novel signal conditioning circuit which is an integral part a measuring electronics developed for the measurement of sodium flow from eddy current flow meter. The flow sensor is fitted in the sodium cooled fast breeder reactor for measuring sodium flow in the outlet of the primary sodium pump and fuel subassemblies at Indira Gandhi Centre for Atomic Research, Kalpakkam, India. It is essential to calculate the error budget and perform the error analysis to evaluate the reliability of the signal conditioning circuit. The work focuses on calculating the error in the circuit, which will affect the absolute accuracy, resolution and drift in the measurement. Based on the specification of each component in the circuit, the worst case error budget and analysis is done. This enables to design a circuit that produce less error even when operated in the worst possible conditions by making comparison of all possible component errors.

A new acoustic leak detection system for sodium-cooled reactor steam generators using a delay-andsum beamformer is proposed. The major advantage of the delay-and-sum beamformer is that it could provide information on the acoustic source direction. An acoustic source of a sodium-water reaction is supposed to be localized, while the background noise of the steam generator operation is uniformly distributed in the steam generator tube region. Therefore, the delay-and-sum beamformer could distinguish the acoustic source of the sodium-water reaction from the steam generator background noise. In this paper, results of numerical analyses are provided to show the fundamental feasibility of the new method.