Masaru Hirabayashi

ACOUSTIC PROPERTIES OF Pb-17Li ALLOY FOR ULTRASONIC DOPPLER VELOCIMETRY

Abstract In a lead-lithium (Pb-17Li) liquid metal blanket concept, Pb-17Li eutectic alloy circulates both as breeder and coolant under a strong plasma-confining magnetic field, experiencing magneto-hydro-dynamic (MHD) force: Lorentz force. An important aspect of the bilateral US/Japan collaboration on Tritium, Irradiations, and Thermofluid for America and Nippon (TITAN) is to investigate tritium behavior and thermal control in the Pb-17Li eutectic alloy, flow and heat transfer characterizations, and mitigation of MHD effects. The present paper focuses on Ultrasonic Doppler Velocimetry (UDV) as an effective diagnostic to measure the Pb-17Li flow in the presence of the strong magnetic field. This paper firstly describes a favorable wetting material for high-temperature transducer. Next, the acoustic property database of Pb-17Li eutectic alloy is presented. Finally, material analyses after high temperature measurements are performed to discuss the durability of titanium transducer.

Velocity Profile Measurement of Lead-Lithium Flows by High-Temperature Ultrasonic Doppler Velocimetry

Abstract This paper describes a high-temperature ultrasonic Doppler Velocimetry (HT-UDV) technique that has been successfully applied to measure velocity profiles of the lead-lithium eutectic alloy (PbLi) flows. The impact of tracer particles is investigated to determine requirements for HT-UDV measurement of PbLi flows. The HT-UDV system is tested on a PbLi flow driven by a rotating-disk in an inert atmosphere. We find that a sufficient amount of particles contained in the molten PbLi are required to successfully measure PbLi velocity profiles by HT-UDV. An X-ray diffraction analysis is performed to identify those particles in PbLi, and indicates that those particles were made of the lead mono-oxide (PbO). Since the specific densities of PbLi and PbO are close to each other, the PbO particles are expected to be well-dispersed in the bulk of molten PbLi. We conclude that the excellent dispersion of PbO particles enables the HT-UDV to obtain reliable velocity profiles for operation times of around 12 hours.

High-Temperature Ultrasonic Doppler Velocimetry for Lead-Lithium Flows

Nuclear fusion reactors are a promising candidate of the future power source. Magnetic confinement fusion (MCF) blankets adopt high-temperature liquid metals (LM) such as the lead-lithium eutectic alloy (PbLi), as a coolant/tritium breeder. Developments of the LM-MCF blankets require comprehensive understanding of the high-temperature LM flows under the influence of the plasma-confining magnetic field. A high-temperature ultrasonic Doppler velocimetry (HT-UDV) has been developed as a flow diagnostic technique to acquire local velocity profiles of the opaque, high-temperature LM flow. This paper describes HT-UDV technique that has been successfully applied to measure velocity profiles of PbLi flows. The impact of tracer particles is investigated to determine requirements for HT-UDV measurement of PbLi flows. The HT-UDV system is tested on a PbLi flow driven by a rotating-disk in an inert atmosphere. We find that a sufficient amount of particles contained in the molten PbLi are required to successfully measure PbLi velocity profiles by HT-UDV. An X-ray diffraction analysis is performed to identify those particles in PbLi, and indicates that those particles were made of the lead mono-oxide (PbO). Since the specific densities of PbLi and PbO are close to each other, the PbO particles are expected to be well-dispersed in the bulk of molten PbLi. We conclude that the excellent dispersion of PbO particles enables the HT-UDV to obtain reliable velocity profiles for operation times of around 12 h.

Reaction, Transport and Settling Behavior of Lead-Bismuth Eutectic in Flowing Liquid Sodium

The experimental study has been carried out to investigate reaction, transport and settling behavior of lead-bismuth eutectic (LBE) in flowing liquid sodium. In the test, 168g of LBE were poured into flowing sodium from the top of a vertical-type sodium loop which contained 23.2 kg of sodium. The initial temperature of LBE and sodium was 673K. The flow rate and the maximum velocity of sodium in the loop were controlled and measured at 20 dm3 /min and 1 m/sec, respectively, using an electro-magnetic pump and an electro-magnetic flow meter. The sodium loop has a settling chamber at the lower part to investigate the concentration decrease behavior of solid particle reaction products in the sodium due to the settling effect. The concentration was measured by sodium sampling from the 11 positions of the loop during the experiment and its post-test chemical analysis. The temperature changes at the various parts of the loop were also measured during the experiment by thermo-couples attached on the outer surface of the loop. Ultrasonic detectors were attached on the outer surface of the loop below the position of a LBE pour nozzle to demonstrate the utility as a leak detector.Copyright

Ultrasonic Doppler Velocimetry Experiment of Lead-Lithium Flow with Oroshhi-2 Loop

Abstract The lead-lithium eutectic alloy (PbLi) is a promising coolant for nuclear fusion reactors. Although PbLi flow and heat transfer in a nuclear fusion reactor condition needs to be comprehended, no velocity profile measurement techniques have been developed yet. Since PbLi is a high-temperature liquid metal, ultrasonic Doppler velocimetry (UDV) is a promising method. In the present study, we investigated a UDV measurement in a high-purity PbLi forced convection loop environment. In summary, naturally contained oxide particles as flow tracers could differ by PbLi purity, and this difference could influence UDV measurability.

Experimental Investigation on Contact Angles of Molten Lead–Lithium on Silicon Carbide Surface

A contact angle database of a molten lead–lithium eutectic alloy (PbLi) droplet on a silicon carbide (SiC) is basic information for research and development both of magnetic confinement fusion (MCF) and inertia confinement fusion (ICF) blankets. PbLi coolant/breeder flows in the coolant channel made of the SiC walls will experience a flow slip at the wall, called as a magnetohydrodynamic (MHD) slip flow. An ICF blanket adopts a molten PbLi film flow along the SiC first wall. The PbLi contact angle database is necessary for numerically predicting the molten PbLi film flow behaviors. The present study is attempted to measure the contact angles formed between the molten PbLi and the various SiC surfaces, e.g. a chemical vapor deposition (CVD) SiC and a nano-infiltration and transient eutectic-phase (NITE) SiC/SiC composite in an inert atmosphere in order to examine an initial PbLi wettability. As the results, the molten PbLi contact angle database is obtained, which covers the PbLi temperature from 250 to 400°C on the surface-polished and unpolished SiC, respectively.