Through the collaboration of the Japan Atomic Energy Agency and High Energy Accelerator Research Organization, the Japan Proton Accelerator Research Complex (J-PARC) has been constructed. The prime purpose is to use the various secondary particle beams such as neutrons, mesons and neutrinos produced in proton-nucleus reactions. One of the facilities that has already been completed is a materials and life-science experimental facility (MLF) where materials and biological structures are analyzed by neutron beam-scattering experiments. In the MLF, a spallation neutron source that provides a high-intensity pulse neutron with low-order meV energy for scattering experiments has been completed, and has successfully produced the desired neutrons. Neutrons produced by spallation reaction have high-order MeV energy, and the high-energy neutron is then transformed to meV-order energy by passing it through a supercritical hydrogen moderator. Therefore, a cryogenic hydrogen system is equipped in the spallation neutron source system. This paper describes the first operation results of the cryogenic hydrogen system.
It is expected that liquid hydrogen (LH2) will be utilized for energy transportation and storage. The LH2 maintained in storage tanks is capable of generating electric power for a long time through fuel cells (FCs) without emission of carbon dioxide (CO2), and can cool high-temperature superconducting (HTS) machines, such as SMES and HTS cable, as well. We propose a hybrid energy transportation system composed of LH2 transfer pipeline, a FC system and HTS cable. We studied the power efficiency of the hybrid system and the pipeline design. We estimated the loss in the LH2 transfer pipeline with HTS cable and optimized the pipeline design. It was found that the hybrid energy transportation system has lower loss than conventional electric power cable. Since this system can transport not only LH2, but also large electric power with small loss, twice the amount of electric power can be supplied when large power load is required at peak times.
As a thermal property of MgB2 wires, we observed the propagation velocity of a normal zone for those immersed in liquid helium. The normal zone propagation was initiated by a resistive heater and the propagation velocity was estimated from the response of voltage difference between potential taps attached to the wire in a transverse magnetic field. The specimen was a mono-filamentary bare wire with a composite sheath of iron and copper. A part of the wire was cooled directly by liquid helium and the other was covered with a vacuum-grease layer for thermal insulation. The propagation velocity observed in each part was of a very low level in comparison with typical ones for usual NbTi wires, which may come from the high critical temperature and the low overall current density. We numerically calculate the propagation velocity with transient cooling models and discuss the normal zone propagation in relation to the cooling processes. We also evaluated the propagation of the normal zone in the MgB2 wires with advanced transport properties, which were attained in short specimens, under the condition of conduction cooling in a wide range of operation temperatures.
The design studies on the force-free helical-type fusion reactor (FFHR) have been carried out with collaborations between universities and the National Institute for Fusion Science in Japan. The output of the electric power was optimized to 1 GW. Co-generation of hydrogen and electricity by steam electrolysis was applied. One-hundred tons per day of liquid hydrogen and 824 MW of electricity can be produced during off-peak time. The applicability for a 1 GW-class hybrid energy transfer line of hydrogen and electricity was investigated. The target distance of the hybrid energy transfer line was 100 km. A hydrogen refrigeration station was placed at intervals of every 10 km. The rated current and withstand voltage of the DC power lines were 10 kA and 100 kV respectively. To keep the liquid state of hydrogen present throughout the unit section, the temperature and pressure of the inlet points were set to 17 K and 0.4 MPa respectively. When the heat leak into the liquid hydrogen was 1.0 W/m (expected value), the temperature at the outlet was 18.1 K. The power consumption of the 20 kW-class refrigerator was estimated to be 1.32 MW. The total power consumption for the hybrid energy transfer line of 100 km in length was 13.2 MW. This value is equivalent to 1.3% of the transport capacity of 1 GW.
Environmental problems are an urgent subject to be solved for humankind. Hydrogen is clean and carbon dioxide (CO2) free, and superconducting devices have energy-saving merits. The combination of liquid hydrogen (LH2) and superconducting devices provides an environment-friendly system. We propose an emergency power supply composed of LH2-cooled superconducting magnetic energy storage (SMES) and fuel cells. The power supply is intended to be used for building such as hospitals; fully utilizing the merit of LH2 as a high-density energy reservoir and that of SMES as a quick-response power supply. In this paper, the system configuration, development scenario and design of the system are described.