Experimental simulation of high-temperature and high-pressure annular two-phase flow using an HFC134a-ethanol system; Characterization of disturbance wave flow

Zhang, H.*; 梅原 裕太郎*; 堀口 直樹; 吉田 啓之; 江藤 淳朗*; 森 昌司*

Energy, 335, p.138090_1 - 138090_18, 2025/10

https://doi.org/10.1016/j.energy.2025.138090

原子力発電は、カーボンニュートラルな未来を実現するための重要な低炭素エネルギー源である。沸騰水型原子炉(BWR)では、燃料棒周囲における蒸気と水の環状流が原子炉の安全性にとって極めて重要であるが、その高温高圧条件(285C、7MPa)により、直接計測が困難である。この問題に対処するため、我々はHFC134a-エタノール系を低温定圧条件(40C、0.7MPa)で用いることで、BWRの液膜流の模擬実験を実施した。高速度カメラと定電流法を用いて、液膜特性、波速度および周波数を分析した。また表面張力と界面せん断応力の影響を調査した。さらに基底液膜厚さについて新たな相関関係を提案した。

Prediction of interfacial shear stress and pressure drop in vertical two-phase annular flow

Zhang, H.*; 梅原 裕太郎*; 吉田 啓之; 森 昌司*

International Journal of Heat and Mass Transfer, 218, p.124750_1 - 124750_11, 2024/01

https://doi.org/10.1016/j.ijheatmasstransfer.2023.124750

The interfacial shear stress and pressure drop of an upward vertical annular flow of nitrogen-water, HFC134a-water, and nitrogen-95% ethanol solution were comprehensively investigated considering the effect of the liquid-gas density ratio and surface tension. A direct link between the disturbance wave height and equivalent sand-grain roughness was noted through the analogy with the famous Moody chart for single-phase turbulent flows. A predictive model of the interfacial friction factor was developed based on this finding. To predict the pressure drop of the annular flow, a new model with good predictive performance for annular flows of various working fluids including steam-water under boiling water reactor operating condition (286C and 7MPa) was proposed.

Effect of gas density and surface tension on liquid film thickness in vertical upward disturbance wave flow

Zhang, H.*; 森 昌司*; 久野 努*; 吉田 啓之

International Journal of Multiphase Flow, 159, p.104342_1 - 104342_15, 2023/02

https://doi.org/10.1016/j.ijmultiphaseflow.2022.104342

At the gas-liquid interface, disturbance waves with various heights commonly arise. Because the thin liquid film between two successive disturbance waves leads to the dryout on the heating surface and limits the performance of the heating components, complete knowledge of the film thickness and disturbance waves is crucial. However, most existing experimental data and analysis are limited to near atmospheric conditions, and the liquid gas density ratio is much higher than in practical nuclear applications. In this study, we use nitrogen gas and water under the system pressures of 0.2 and 0.4 MPa and HFC134a gas and water under the system pressure of 0.7 MPa. The density ratio can be varied between 32 and 434. Based on experimental results, two models are proposed to predict the averaged film thickness and wave height, which are then compared with previous data.

Sodium-cooled Fast Reactors

大島 宏之; 森下 正樹*; 相澤 康介; 安藤 勝訓; 芦田 貴志; 近澤 佳隆; 堂田 哲広; 江沼 康弘; 江連 俊樹; 深野 義隆; et al.

Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07

https://shop.elsevier.com/books/sodium-cooled-fast-reactors/morishita/978-0-12-824076-2

ナトリウム冷却高速炉(SFR: Sodium-cooled Fast Reactor)の歴史や、利点、課題を踏まえた安全性、設計、運用、メンテナンスなどについて解説する。AIを利用した設計手法など、SFRの実用化に向けた設計や研究開発についても述べる。

Spin excitations of the =1/2 one-dimensional Ising-like antiferromagnet BaCoVO in transverse magnetic fields

奥谷 顕*; 大西 弘明; 木村 尚次郎*; 竹内 徹也*; 木田 孝則*; 森 道康; 三宅 厚志*; 徳永 将史*; 金道 浩一*; 萩原 政幸*

Journal of the Physical Society of Japan, 90(4), p.044704_1 - 044704_9, 2021/04

https://doi.org/10.7566/JPSJ.90.044704

The high-field multifrequency electron spin resonance (ESR), the magnetization, and the specific heat of single crystals of BaCoVO (a quasi-one-dimensional Ising-like antiferromagnet with ) were measured in two different transverse magnetic fields: and . A softening of the lowest ESR mode was observed near the saturation field of the magnetization around 40 T in , whereas it occurs around 10 T in , far below the saturation field. These observations were reproduced by numerical calculations using the density-matrix renormalization group methods, including the staggered magnetic fields induced by a uniform external magnetic field and the interchain magnetic exchange interaction. We found that the directional dependence of the lowest mode originates mainly from the remarkable angular dependence of the induced magnetic field. The interchain interaction is also quantitatively important for reproducing the experimental results. The directional dependence of the lowest mode is demonstrated by the particle-hole excitation of spinons using the Jordan-Wigner transformation.

Magnetic structure and dispersion relation of the =1/2 quasi-one-dimensional Ising-like antiferromagnet BaCoVO in a transverse magnetic field

松田 雅昌*; 大西 弘明; 奥谷 顕*; Ma, J.*; Agrawal, H.*; Hong, T.*; Pajerowski, D. M.*; Copley, J. R. D.*; 奥西 巧一*; 森 道康; et al.

Physical Review B, 96(2), p.024439_1 - 024439_8, 2017/07

https://doi.org/10.1103/PhysRevB.96.024439

BaCoVO consists of Co chains, in which Co ion carries a fictitious spin with Ising anisotropy. We performed elastic and inelastic neutron scattering experiments in BaCoVO in magnetic field perpendicular to the axis which is the chain direction. With applying magnetic field along the axis at 3.5 K, the antiferromagnetic order with the easy axis along the axis, observed in zero magnetic field, is completely suppressed at 8 T, while the magnetic field gradually induces an antiferromagnetic order with the spin component along the axis. We also studied magnetic excitations as a function of transverse magnetic field. The lower boundary of the spinon excitations splits gradually with increasing magnetic field. The overall feature of the magnetic excitation spectra in magnetic field is reproduced by the theoretical calculation based on the spin antiferromagnetic chain model, which predicts that the dynamic magnetic structure factor of the spin component along the chain direction is enhanced and that along the field direction has clear incommensurate correlations.

幌延深地層研究計画における地震研究; 地震観測データおよびそれらの解析結果(20032012年度)

落合 彰二; 浅森 浩一; 常盤 哲也; 野原 壯; 松岡 稔幸

JAEA-Research 2014-002, 69 Pages, 2014/03

JAEA-Research-2014-002.pdf:7.39MB

本研究の目的は、地質環境の長期安定性に関する地震データを得るために必要な観測技術と解析技術を検討することである。幌延地域を事例とした地震観測網の整備と約9年間の観測を通じて、多雪寒冷な環境下に対するピットを用いた地震計設置の有効性などの観測技術を確認した。比較的軟弱な地盤における観測点の性能は、バックグラウンドノイズと地震を識別できる加速度が1mGal程度であった。解析技術については、観測データが震源決定に有効な範囲を確認した。また、Multiplet-clustaring法とDouble-Difference法(DD法)を適用することにより、震源決定精度を高めるための解析条件を確認した。これらの解析法は震源が集中するときに適用性が高いと推定された。DD法は震源に近い観測点を含む多数のデータを用いた結果、解析結果の信頼性が向上した。メカニズム解を求めた結果、東西圧縮の逆断層型が認められた。これは想定されている広域応力場や地質構造と調和した。

Development of a photoemission DC Gun at JAEA

西森 信行; 永井 良治; 松葉 俊哉; 羽島 良一; 山本 将博*; 本田 洋介*; 宮島 司*; 飯島 北斗*; 栗木 雅夫*; 桑原 真人*; et al.

Proceedings of 34th International Free Electron Laser Conference (FEL 2012) (Internet), p.161 - 164, 2012/08

http://accelconf.web.cern.ch/accelconf/FEL2012/papers/mopd53.pdf

The next generation light source such as X-ray FEL oscillator requires high brightness electron gun with megahertz repetition rate. We have developed a photoemission DC gun at JAEA. By employing a segmented insulator with rings which guard the ceramics from field emission, we successfully applied 500-kV on the ceramics with a center stem electrode for eight hours without any discharge in 2009. This high voltage testing was performed with a simple configuration without NEG pumps and electrodes. In 2011 we reached 526-kV with NEG pumps and electrodes, before suffering another field emission problem from the cathode electrode. The problem may be attributed to small dust inside our gun chamber. We found wiping the cathode electrode with a lint free tissue could remove the field emission site effectively. Noble gas conditioning is also planned to remove the emission site without air exposure of the gun chamber.

Development of a 500-kV photocathode DC gun for ERLs

西森 信行; 永井 良治; 山本 将博*; 本田 洋介*; 宮島 司*; 飯島 北斗*; 栗木 雅夫*; 桑原 真人*; 奥見 正治*; 中西 彊*; et al.

Journal of Physics; Conference Series, 298, p.012005_1 - 012005_6, 2011/06

https://doi.org/10.1088/1742-6596/298/1/012005

An electron gun capable of delivering high current and high brightness electron beam is indispensable for ERL light sources. A high voltage photocathode DC gun is a promising gun for such new light sources. It is however difficult to apply DC high voltage on a ceramic insulator with a rod supporting cathode electrode because of field emission from the rod. In order to mitigate the problem, we have employed a segmented insulator with rings which guard the ceramics from the field emission. We have recently succeeded in applying 500-kV on the ceramics for eight hours without any discharge. Our recent development will be presented at the workshop.

ERL放射光源500-kV光陰極DC電子銃開発の現状

西森 信行; 永井 良治; 羽島 良一; 山本 将博*; 宮島 司*; 本田 洋介*; 武藤 俊哉*; 飯島 北斗*; 栗木 雅夫*; 桑原 真人*; et al.

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.802 - 805, 2010/08

http://www.pasj.jp/web_publish/pasj7/proceedings/P_5PM/P_EH_5PM/THPS013.pdf

次世代エネルギー回収リニアック光源のために、500-kV光陰極DC電子銃開発を行っている。電子銃に必要な非蒸発型ゲッターポンプとカソード・アノード電極を設計し、容器へのインストールを行った。電子銃容器の真空度は210パスカル以下に達し、380-kVまでの高電圧コンディショニングにも成功した。光陰極準備容器と電子銃容器の接続を終え、ビーム生成の準備を行っている。