As one of the expected solutions for the safe design and operation of nuclear power plants, the further improvements of nuclear materials and fuels are indispensable. We deal with research and development of materials for fusion reactors, advanced fission reactors (Generation IV), and current light water reactors (LWR). The main aspects are to reveal fundamental mechanism of the degradation process under extreme environments, such as irradiation, corrosion and hydrogenation, in Fe-based and Zr-based alloys. Developments of high-performance materials and testing methods are also of our interest. The following techniques are currently applied: microscopy like TEM, HVEM, TEM-accelerator, SEM/EBSD etc.; mechanical tests like advanced expansion-due-to-compression (A-EDC) test, tensile, creep and nano-hardness etc.; and computer simulations like FEM and MD.
Fission, Fusion, Nuclear materials, Nuclear fuels, Extreme environment, Degradation mechanism, Radiation effects
Development of Medical Technology and Plant Maintenance Technique based on electromagnetic simulation:
(1) Electromagnetic diagnosis of power plant instruments,
(2) Time-series data prediction of lung tumor movement for Chasing Irradiation Therapy
(3) Movie prediction system.
Maintenance, Medical Technology, Movie Prediction
Project Associate Professor
Experimental and Numerical Nuclear Thermal-Hydraulics for Nuclear Safety and Severe Accidents
Experimental methods and the instruments have reached to very advanced levels recently. In parallel, the computational methods gained tremendous capacity and have become capable of simulating more complicated systems than before by employing sophisticated modeling techniques. To validate the results of the digital world, high-quality experimental data (diverse, multi-dimensional, high-resolution, and accurate) is extremely needed. To enhance the nuclear safety and the understanding of the nuclear accidents, we perform experiments and numerical simulations related to thermal-hydraulics. We use/develop advanced visualization/measurement techniques for fluid flow and heat flow (PIV, PIV/TSP, Shadowgraphy etc.) diagnostics to acquire high-quality real world data. The computational tools such as OpenFOAM and RELAP/SCDAP and their models validated with experiments enhance our understandings of the thermal-hydraulics mechanisms prevalent in the nuclear power plant systems.
Nuclear Thermal-Hydraulics, Nuclear Safety, Severe Accident, Particle Image Velocimetry (PIV), OpenFOAM
Fujii laboratory has been working on the research topics of the feasibility analysis of various alternative energy supply technologies, and policy evaluation for international energy security and environmental issues using a global energy system model built with large-scale mathematical programming on the computers. Moreover, research topics of energy management, such as institutional design of deregulated electricity markets and optimal strategy planning of energy procurement under uncertainty, have also been investigated using variety of analytical techniques of stochastic dynamic programming, financial engineering, and multi-agent simulation with reinforcement learning.
In Fujii laboratory, since we try to find the solutions for the energy problems of 100 years and for the social system which is not realized yet, we welcome students who have the interest to learn various fields, and those who have strong imagination to consider the future of foreign countries.
Energy Economic Systems, Technology and Policy Assessment, Optimization, Stochastic Programming
Recent progress has been made in engineering solid state lasers to extend their wavelengths and intensities, which leads less photon-cost and narrower bandwidth of the laser wavelength. Laser manipulation of atoms and molecules is one of the fruitful fields due to it. In nuclear engineering, the isotope manipulation and measurement are fundamental technology to pursue. Measurement of rare isotopes is also important for nuclear security or forensic science. We investigate interactions between photons and atoms to extend capability of the laser manipulation for nuclear engineering.
laser science, Atomic and molecular science, Isotope engineering
We study the interaction of a laser pulse and an ion beam with matter through theory and simulations. Our research interest is a new field called high-field phenomena and attosecond science, which studies the quantum dynamics in an ultrashort intense laser field. Especially, we investigate highly nonlinear processes such as high-harmonic generation and tunneling ionization as well as attosecond electron dynamics in atoms and molecules, based on atomic and plasma physics as well as quantum chemistry. Also, we develop a sophisticated method of dose calculation for heavy-ion cancer therapy, which also runs on the K supercomputer.
High-order harmonic generation, High-field physics, Ab initio simulations, Monte-Carlo method
Our research focuses on modeling of risk due to natural hazards (earthquake, strong wind, etc.) and risk governance framework, from the standpoint of disaster prevention and mitigation of nuclear facilities, buildings and infrastructures:
(1) Risk analysis of spatially-distributed systems
(2) Ground motion prediction and probabilistic seismic hazard analysis
(3) Real-time earthquake disaster mitigation
(4) Risk governance framework of important facilities against natural hazards
Natural disaster modeling, Earthquake engineering, Risk governance
Energy plants are complex systems related with thermal-fluid-structural mechanics. Understanding of essential mechanism of multi-physics phenomena will lead to development of systematic models on thermal load - structural response - material strength in plants. These enable superior design which can satisfy both plant safety and economics.
Most of them are joint research programs with external companies. They will give you educational chance to learn academic research organization and project management.
Through concrete research on structural design of fast breeder reactors, students can learn rational and general methodologies applicable to other fields.
Nuclear Structural Engineering, Elevated Temperature Structural Design, Fast Breeder Reactor
Energy security is a key agenda to address for sustaining socioeconomic activities under various structural and contingency risks such as the depletion of fossil fuel and energy supply disruption. In order to formulate effective technical and political measures for enhancing energy security under those risks and constraints, we need to comprehensively understand economics and international energy market as well as the engineering aspect of energy technology. The research theme in our group is to develop a mathematical and computational energy-economic model to analyze the optimal strategy for the deployment of energy technologies and to discuss energy policy firmly based on the simulated results derived from the model.
Energy security, Energy-economic model, Mathematical optimization, Econometrics
Core degradation was occurred in the accident of Fukushima-Daiichi nuclear power plant (NPP). We are trying to clarify what happened in the sever accident of the NPP by simulating thermal hydraulic behavior including multi-phase and multi-physics phenomena. Physical model is going to be developed for chemical reaction, mixing, melting and solidification of different materials. Especially, particle methods are used to analyze melting and solidification behavior. We are trying to figure out phenomena in sever accident by simulating complex thermal hydraulic behaviour.
In our laboratory, thermal hydraulic experiments are also conducted. To see practical behavior by experiments is also important for complex physical modeling. Well-developed models based on experiments are hopefully applied not to only server accident analysis but also to other fields: civil engineering, metallurgy, resin molding and so on. We are challenging to clarify the sever accident thermal hydraulic behavior using both experiment and simulation.
Numerical simulation, Particle method, Severe accident, Multi-physics modeling, Thermal hydraulics
I am working on radiation chemistry and irradiation effects of polymer materials by using ion and electron beam accelerators.
Radiation chemistry, Radiation application, Radiation degradation, Polymer material
Accelerator Mass Spectrometry (AMS) can analyze extremely rare long-lived radio isotopes such as 10Be(half life = 1.36x106 yr), 14C(5,730 yr), 26Al(7.2x105 yr),36Cl(3.01x105 yr), 129I(1.57x107 yr). These rare isotopes form special isotope systems with their stable isotopes which have precise information about earth environment system. Most famous isotope system is the 14C/12C system well known to be used for dating. Our laboratory has a 5MV tandem accelerator and developed multi-nuclide AMS system of which the performance retains world's top level. While we are applying AMS to various interdisciplinary research fields from archaeological to earth environmental sciences, recently we especially focus on the 129I/127I system. As iodine has a close relation with organic matter and is often found with important carbon reservoir such as methane hydrates and soils, we consider 129I/127I system is an important clue to elucidate the total carbon dynamics.
Ion beam, AMS, Isotope geochemistry, Radioisotope environment assessment
Our academic objective is to realize a new innovative high-energy-resolution spectroscopy for nuclear structure investigations, radioactive or non-radioactive nuclide identifications, material analyses, and radiotherapy. For example, non-destructive analysis of nuclear materials for safeguards and nuclear forensic requires improvement in accuracy and sensitivity. The precision spectroscopy of hard X-ray and gamma ray from the nuclear materials is powerful tool for the identification of the plutonium, uranium, actinide and their decay products. However it needs to resolve their X-ray or gamma ray peaks in the complex spectrum of around 100keV region, which cannot be resolved by the conventional detectors. Therefore, we have developed the superconducting radiation sensor with the ultra-high energy resolution. Now our research group has already obtained the world top energy resolution in high-energy gamma-ray region and also, tried to measure gamma-rays from fission products with this superconducting detector.
Superconductivity, Nanotechnology, Gamma-ray spectroscopy, Charge particle therapy
"Visualization" is the key technology on 21 century. We focused on the Information Visualization and Quantitative Visualization. The huge amount of data will be visualized to understand the complex phenomena and/or to resolve the core mechanism of the complex systems. The laser and high-speed camera will resolve the invisible world with quantitative information. We are the world top class laboratory for quantitative visualization.
In the Nuclear Safety, visualization is also the key system. The complex huge system, e.g. Nuclear Power Plant, will be resolved using the visualization technology. The Nuclear Energy will be a promising source of energy to help the world, especially developing countries. However, public understandings will be needed, especially in Japan. Using the visualization technology, we will provide an open access of the Nuclear Energy.
We really need a trailblazer for the complex future.
Visualization, Nuclear safety, Severe accident
It is duty of our generation to settle the issues of nuclear waste disposal. Geological disposal is a feasible option for high-level wastes or spent fuels, where various basic research and R&D are still needed to improve the reliability. Chemistry of radionuclides is a key foundation to realize a well-accepted disposal system. Thus, we are pursuing understanding and modeling of the chemistry that governs the interaction of radionuclides with materials of engineering barriers and the migration of radionuclides in subsurface environments, using sophisticated spectroscopy with X-ray, laser, and neutron, chromatographic techniques, and computer simulation. Knowledge obtained through the research has been applied to the modeling of chemodynamics of radionuclides released from the accident of the Fukushima Daiichi nuclear power plant or other non-radioactive pollutants in environments. Any student who has an interest in the issue of nuclear waste disposal are welcomed, no matter what academic backgrounds they have.
Nuclear waste disposal, Physical chemistry, Geochemistry, Actinide chemistry
We study multiphysics modeling for computational granular dynamics, namely, numerical simulations of solid-fluid and solid particle-elastic body interaction problems. We encounter these problems in various fields including nuclear engineering, chemical engineering, mechanical engineering, civil engineering, pharmaceutical, etc. Numerical studies on the problems were challenging since these were hardly simulated because of the complicated phenomena and excessive calculation cost. Accordingly, our research topics becomes wide ranging, for example, slurry suspension, magneto-rheological fluids, fluidized beds, debris flows, slope failure. At present, we develop new models to perform the simulations by using Lagrangian-Lagrangian or Eulerian-Lagrangian approaches. Our original technologies become important in engineering and science.
Computational granular dynamics, Discrete element method, Multiphiscs modeling
High field physics and attosecond science are rapidly progressing, in which dynamics of electrons in matters are directly measured and even controlled, using ultra-short high-intensity laser pulses. We are developing state-of-the-art theoretical and computational methods to solve time-dependent Schrödinger equation of multielectron systems interacting with intense laser fields, aiming at ab initio study of nonlinearly nonperturbative phenomena such as tunneling ionization, high harmonic generation, and nonsequential multiple ionization.
High field physics, Attosecond science, Wave function theory, Density functional theory, Quantum chemistry
Multi-scale simulation and experimental studies on microscopic and macroscopic behaviors of nuclear materials under very severe conditions including energetic neutron irradiation are the major topics. I have been leading national projects for ageing management of nuclear reactors components and materials with other universities, national laboratories and industries. Our group is also working on international collaboration on safe long term operation of nuclear systems and seismic safety through intensive collaboration with IAEA and OECD/NEA .
Safety and Knowledge Management for Nuclear Systems, Multiscale Modeling of Materials
In order to complete the decommissioning of Fukushima Dai-ichi NPP, we need to challenge and overcome the difficulties which no one has ever experienced. The key technology for decommissioning of the accident plants is how to solve the unsteady state problems caused by remarkable changes of environment, circumstances and the states of the plant condition with the lapse of time. Main theme of this course is finding the tasks and their solutions for decommissioning through evaluation of phenomena which may occur in the future and also though making the scenario with experiments such as material and thermal-hydraulic tests. This course will not only deepen your skill & knowledge on decommissioning, but also give you an opportunity to understand the importance of the project management and the way of System Thinking for a complex world which you will face in the future.
Decommissioning, System dynamics, Risk assessment, Resilience engineering
Radiation measurements are very important in many science and technology areas. We develop quantum radiation detectors for various applications in many areas such as medical imaging, industrial imaging, basic science, etc. Microfabrication techniques, microelectronics and computer hardware techniques, and simulation calculations are effectively used in our research.
Radiation measurements, Gamma-ray imaging, Environmental radiation, Neutron detectors, Signal processing
We study material science and chemical engineering for advanced energy systems including the next-generation fission reactor, fusion reactor and nuclear fuel reprocessing systems. Elemental techniques for hydrogen energy system including fuel cell, hydrogen storage, etc. are also investigated. In addition, material processing with high-energy particles such as neutrons, ions, electrons and plasma particles for advanced material preparation and property modification are our research targets.
Reactor materials, Hydrogen energy,High-energy particles
We are developing advanced and compact accelerators/lasers such as S-band photocathode RF electron gun and linear accelerator (linac), X-band Compton scattering monochromatic X-ray source, portable X-band linac X-ray source for nondestructive evaluation, X-band linac for pinpoint cancer therapy, fiber laser accelerator for basic radiation biology. Further, we are performing research on X-ray drug deliver system (DDS) for high quality diagnosis and synergy effect of chemical and radiation-therapies. R&D based medical physics are performed.
Portable linear accelerator, Fiber laser, Radiation biology
Science and technologies promise better life and more wealthy society in the future. Eventually, we gain benefits from the fruits. The idea does not adapt to the contemporary society. The societal value of the science and technology is closely concerned with the rational relationship of the technology and the society. Key words of science and technologies in the light of societal view are uncertainties, imaginary skill, unknowns, questioning attitude, rational decision making and so on. Contemporary science and technologies need to be established putting more emphasis on the societal acceptance in terms of risk and benefit, i.e. welfare of the society. Researches necessary to respond to the expectations are for: (1) simulating the technology (to understand phenomena), (2) perceiving the technology (to understand risk), and (3) assessing the technology (to make a decision rationally). Common baseline idea is to be developed by an academic field that deals with the lack of knowledge and unknowns, e.g. uncertainties. Energy is the source and foundation of social infrastructures. The dual aspect, light and shadow (safety and uncertainty), of the energy should be quantitatively understood in whole the society for a good and rational decision-making. Last but not least are, needless to say, the next generation researchers. It is a challenge for those living in Japan that have engraved the experience of nuclear disaster deeply in heart. Please join us for opening the door of risk and safety research.
Risk assessment, Simulation, Unknown, Uncertainty, Decision making, Nuclear safety
Ionizing radiations are closely related to most of the problems in nuclear engineering while they are utilized in practical fields such as cancer treatment in medical field, material processing in industrial field, etc. Understanding their features is essential in order to enhance their advantages as well as to overcome their disadvantages. Sequential events from pico- to microseconds (10−12-10−6 s)) induced by ionizing radiations are all our interest. Examples of research subjects are as follows: "Mechanism of radiation protection and enhancement caused by a tiny amount of chemicals", "water radiolysis (radiation-induced decomposition) with therapeutic high-energy heavy-ion beams", "radiation chemistry in gel matrix for development of polymer gel dosimeter", "effect of seawater constituents on water radiolysis", "gas evolutions from boiling water", etc. In addition, radiation effects at interfaces such as water-polymer (DNA, polysaccharides), water-metal/ceramic, and liquid water-water vapor have not been investigated well. I hope some students make breakthroughs in the frontier.
Radiation effect (physical chemistry, chemistry, and biochemistry), water chemistry in nuclear engineering, cancer therapy, industrial application of radiation, interfaces