経年劣化事象の1つである配管減肉について,現行の配管厚さ測定をベースとした減肉管理とその課題を紹介すると共に,それらを解決するための減肉予測手法を活用した減肉管理の利点の整理・電中研の配管減肉予測手法FALSETについて紹介する。更に,特定の減肉事象への減肉予測技術の活用例についても述べる。

Under certain opening conditions (partial opening) of a steam control valve, the piping system in power plant occasionally experiences large vibrations. To understand valve instability that is responsible for such vibrations, detailed experiments and CFD calculations were performed. As result these investigations, it was found under middle-opening condition, complex three-dimensional (3D) flow structure (valve-attached flow) sets up region leading to high pressure on part body. this rotates...

Defects in p-type oxide/β-Ga2O3 heterojunction diodes were investigated using Cu2O as a case study. Diodes with polycrystalline and epitaxial films analyzed deep-level transient spectroscopy. For both diodes, two electron bulk defects detected, including minority defect at 0.23 eV below EC within majority 0.53 β-Ga2O3. Furthermore, high-density interface state of 4.5 × 1012 cm−2/eV was observed the Cu2O/β-Ga2O3 diode. The presence high density states helped reduce turn-on voltage owing to...

In this work, p-type cuprous oxide (Cu2O) films grown on beta gallium (β-Ga2O3) substrates by magnetron sputtering were reported. The resulting vertical Cu2O/β-Ga2O3 heterojunction p–n diodes demonstrated superior performance compared to devices fabricated with polycrystalline Cu2O thin films. Meanwhile, analysis of the discrepancies between built-in potential and turn-on voltage revealed diverse carrier transport mechanisms in devices. Numerical fitting forward J–V characteristics further...

The boiling water reactor (BWR-3) steam dryer in the Quad Cities (QC) Unit 2 Nuclear Power Plant was damaged by high-cycle fatigue due to acoustic-induced vibration. cause of failure considered as flow-induced acoustic resonance at stub pipes safety relief valve (SRV) main lines (MSLs). be generated interaction between sound field and an unstable shear layer across closed side branches SRVs. We have started a research program on BWR dryers develop methods evaluating loading. Moreover, it is...

In this work, interface traps in β-(AlGa)2O3/Ga2O3 modulation-doped field effect transistor (MODFET) were investigated qualitatively and quantitatively by means of dynamic capacitance dispersion technique. The fabricated MODFET showed drain current modulation demonstrating the behavior. existence two-dimensional electron gas was confirmed plateau region capacitance–voltage (C–V) characteristics. difference profile at multifrequency C–V measurement suggested loss mechanism due to trapping...

A conceptual design of the thermoelectric power conversion system combined with open rack type LNG (liquefied natural gas) vaporizer to make use cold heat is presented. The performance analysis has been made based on module data obtained at cryogenic (CTE) test rig which could realize temperature and fluid dynamic condition vaporizer. Conventional bismuth-telluride modules were tested, however, each encapsulated in stainless steel container achieve water proof. Electricity production cost...

A steam control valve is used to the flow from a generator turbine in power plants. The field usually complicated and transonic. flow-induced vibration can occur may cause unexpected shutdown of plant. An experimental study conducted clarify characteristics valve. In present study, scale effects on condition occurrence various patterns are investigated. Experimental results show including new which have not been reported. Additionally, even under same operation condition, different observed...

Hydrogen diffusion behavior in a cesium adsorption vessel is assessed. The used to remove radioactive substance from contaminated water, which proceeded Fukushima accident. Experiment and numerical calculation are conducted clarify the characteristics of natural circulation vessel. arising temperature difference between inside outside confirmed. We develop an evaluation model predict its prediction agrees well with results obtained by experiment calculation. Using model, we steady transient...

In some cases, a steam control valve in power plant causes large vibration of the piping system under partial opening. For rationalization maintenance and management plant, it is favorable to optimize geometry prevent such vibration. However, difficult understand flow characteristics detail only from experiments because around has complex 3D structure becomes supersonic (M>1). Therefore, useful combine CFD (Computational Fluid Dynamics) for clarification cause optimization geometry....

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Flow-induced acoustic resonances in piping with closed side branches cause severe structural vibration and fatigue damage of components power plants. Practical systems plants often have a steam flow, moreover, the state can be not only dry (i.e., gas single-phase flow superheated steam) but also wet high-quality two-phase mixture saturated water). Although many researchers investigated at branches, under yet been clarified since previous studies were mainly conducted an air flow. Moreover,...

Control valves of the main steam flow for power plants are operated under wide range valve openings and pressure ratios. In present paper, experimental numerical investigations described in order to clarify mechanisms head vibration. Experiments conducted with two types support. One is a flexible support other one an exciter. Results show that vibrations large amplitude appear flexibly supported certain ratio. With exciter, dynamic fluid forces measured. added damping force becomes negative...

Performance of thermoelectric (TE) modules for the TE power conversion system combined with open rack type LNG vaporizer (ORV) is discussed. Most conventional BiTe suffer sudden decrease at cryogenic temperature as low -160°C. This called Mayer-Marschall effect. Authors investigated cause this effect and found that could avoid such data obtained (CTE) test rig which realize fluid dynamic condition ORV presented.

A steam control valve causes vibrations of piping when the opening is in middle condition. For rationalization maintenance and management a plant, valves should be improved, but it difficult to understand flow characteristics detail experimentally because around has complex 3D structure becomes supersonic (M>1). Therefore, necessary clarify cause vibration develop improvements both through CFD (Computational Fluid Dynamics) calculation. First, small-scale air experiments are...

During operation, the BWR-3 steam dryer in Quad Cities Unit 2 Nuclear Power Plant was damaged by high cycle fatigue. The failure attributed to flow-induced acoustic resonance at stub pipes of safety relief valves (SRVs) main lines (MSLs). considered be generated interaction between sound field and an unstable shear layer across closed side branches with SRV pipes. We HITACHI CRIEPI have started a research program on BWR dryers develop their loading evaluation methods. Moreover, it has become...

In industrial fields, as the steam is commonly utilized for heat supply, drying process and so on, it important to be aware of flow rate in view point energy management. However, factory usually wet condition. Though well known that wetness affects flowmeter reading, difficult clarify effects quantitatively actual plants factories, thus far, there has been no established method estimating error caused by flow. this paper, difference ultrasonic reading due was clarified experimentally....

A series of study is presented to develop a prediction method for pipe wall thinning in power plants order improve the maintenance management piping system. In first report, experiments flow-accelerated corrosion (FAC) carbon steel specimens were conducted and basic data FAC rate obtained by setting temperature from 50 150 ℃ pH 7.0 9.8 as main parameters. As this second experimental compared with method. Effective mass transfer coefficient correlation was proposed implemented into...

Nuclear power plants are designed to prevent the damage of safety installations and human due jet impingement when a pipe is ruptured. We have investigated evaluation methods for design basis protection against effects postulated rupture using computational fluid dynamics analysis (CFD). The steam tests particle image velocimetry were conducted in order verify CFD methods. Spread could be visualized. Shapes obtained by almost same as those tests. spread angle free CFD, we found that strongly...

配管減肉に対する流体現象の寄与について説明した．流れ加速型腐食（FAC）とエロージョンでは，壁面への流体作用力が全く異なることを示した．FACの主要因子である乱流物質移動は熱伝達とアナロジがあり，壁面近傍の粘性底層内の分子輸送が支配的とするモデルが実用的である．さらに物質移動は数値流体解析コードで求められる．最後にこれらの手法によりオリフィス，エルボにおける物質移動現象を予測した結果を説明した．

Liquid droplet impingement erosion (LDI) is defined as an phenomenon caused by high-speed attack in a wet steam flow. Pipe wall thinning due to LDI sometimes observed piping system of power plant. In this study, for more realistic evaluation the plant, we conducted experiments flow with apparatus, and tried develop new rate prediction model (LDI model). High speed simulating actual plant condition was employed experiments. As result, cushioning effect liquid film on material surface...

A series of study is presented to develop a prediction method for pipe wall thinning in power plants order improve the maintenance management piping system. As first report, experiments flow-accelerated corrosion (FAC) carbon steel specimens were conducted and basic data obtained, focusing on relatively low temperature condition. FAC rate seen decrease by lowering trend curve tends remains keep considerable level lower around 50 °C. Obtained would mean that susceptibility pipeline condensate...

Flow Accelerated Corrosion (FAC) is well known as a complex phenomana of hyraulics and electro-chemicals. Among the two, this study focused on hydraulic factors affecting FAC. FAC experiments with small rectangular flow duct were conducted in PWR condensate condition. field for experiment was calculated numerical simulation using LES (Large Eddy Simulation) turbulence model. From both experimental results, new model mass transfer coefficient, essential parameters hydraulics, proposed...