Nuclear Materials Engineering
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.
Energy systems analysis for policy and technology assessment
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.
Quantitative analysis of energy security
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.
First-principles calculation of ultrafast intense laser-matter interaction
We study the interaction of lasers with atoms, molecules, and solids using quantum-mechanical first-principles calculation. We are interested in the many-electron dynamics triggered by a laser pulse and the nuclear dynamics induced by the electron dynamics. These are relevant with biological effects of radiation, control of chemical reactions, petahertz electronics, and advanced laser material processing. We actively collaborate with Vienna University of Technology, LMU Munich, Max Planck Institute of Quantum Optics, FERMI free-electron laser, and RIKEN.
Theory and simulations of light-matter interaction
Our laboratory conducts theories and simulations of the interaction between light and matter. In particular, we are a world-leading laboratory in the field of attosecond science, aiming to control the movement of atoms and electrons in materials with ultrashort pulse and high intensity laser. My research themes can be classified into three: theory, implementation, and applications. First, we are developing original theories for accurately solving time-dependent Schrodinger equation to describe light-matter interactions. With theory, you can make a breakthrough using papers and pencils only. Second, you will be trained for both new and old computer skills including C++, Fortran, and python in our group. With computer implementation, you can connect theory with reality. Appealing in the third topic, applications, is that you can use original theory and codes to predict real-world experiments. We are also challenging new researches, including a quantum computer simulations of quantum dynamics. Please join us if you like math, physics, chemistry, programming, or simulations, of if you are interested in theory of light and matters, quantum mechanics, or quantum computer, or if you want to challenge fusion of physics and machine learning.
Severe Accident, Nuclear Safety and Visualization
In the Severe Accident of Nuclear Power Plant, melted fuel relocates to lower plenum with dissolving the SUS and Zircaloy structures. The accident at Fukushima-Daiichi NPP has lots of unknowns and unresolved issues. In order to operate the nuclear plant safely, the non-linear severe accident phenomena have to be known. In our laboratory, the thermal-hydraulic phenomena related to the Severe Accident had been studied with experiment and numerical simulation. These results had been applied to international collaborative research, R&D for next generation nuclear reactor and decommissioning activity of Fukushima Daiichi.
"Visualization" is the key technology on 21 century. The huge amount of data will be visualized 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 and Severe Accidents are 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.
Fukushima Daiichi Decommissioning, Fuel debris retrieval, Waste management
In order to complete the decommissioning of Fukushima Daiichi 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 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 research 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.
Experimental and Numerical Nuclear Thermal-Hydraulics for Nuclear Safety and Accidents
The technology of the experimental instruments has reached to very advanced levels recently. In parallel, the computational methods and resources gained tremendous capacity that can employ sophisticated modeling techniques for real-life problems. To validate the results of the digital world, a high-quality experimental data set (diverse, multi-dimensional, high-resolution, and accurate) is extremely needed. To understand the sophisticated dynamics of nuclear accidents and to enhance the nuclear safety, we perform experiments and numerical simulations related to thermal-hydraulics phenomena existing in nuclear systems. We use/develop advanced visualization and measurement techniques for fluid flow and heat flow (PIV, PIV/TSP, Shadowgraphy etc.) diagnostics to acquire high-quality real-world data. We use the computational tools such as OpenFOAM and other CFD codes, and validate their models with the experimental results which are obtained from small-scale setups, and extrapolate acquired knowledge to real-scale problems.
Deepening of Risk and Utilizing of Risk on Decision Making in Engineering Issue
We have no engineering system with absolute safety. Accordingly, A qualitative and quantitative understanding of risk on the system will be one of the most key issues to discuss its safety and to make a decision concerning with an application of the system.
Since a nuclear power plant is a huge and complex engineering system, intrinsic risks in the plant include large uncertainties and numerous scenarios. Hence, a ratiocinative methodology will be of importance to clarify the risks. We have been developing the methodology based on experimental approaches as well as numerical simulation technology.
So as to utilize an engineering technology efficiently, one needs two-sided characteristics of; one’s credible expertise and a sense of overall balance. Accordingly, we have also investigated a qualitative characteristic of the information concerning with the risk, which is obtained in the risk assessment, and its elemental role on decision making.
Advanced multi-physics simulation technologies
I believe that my group is world-leading in the modeling of granular and multiphase flows. My group concentrates on the development of advanced multi-physics models in nuclear engineering, environment & energy engineering, and food & pharmaceutical engineering. At present, I carry out lots of multi-discipline projects with external partners all over the world. The worldwide impact of our research is shown since our research achievements have been published in authoritative academic journals. As a matter of course, my students have won lots of awards in conferences. Besides, foremost professors often visit my group and give a wonderful talk in a seminar. Thus, my group has been already accepted to be established in my fields. Hence, my students can go ahead their studies under exciting environment. I warmly welcome ambitious and highly motivated students who can improve their skills and knowledge positively. I can support the students to obtain brilliant accomplishments.
Safety and reliability of high temperature structural systems
Our laboratory contributes to the development of engineering standards. Our work aims at the development of practical strength and response models by identifying dominant physical phenomenon through experimental methods. By understanding the behavior of various components, we aim to apply this method to entire plant structures; thus, enabling design by analysis methods throughout the structural design process of plants and reactors.
Furthermore, in order to improve the safety and reliability of future energy plants, we developed innovative evaluation methods considering uncertainty of strength and load parameters, improving the accuracy of verification and inspection evaluations.
Establishment of new AI monitoring technology for humans and objects
AI can be said to be a surrogate brain for humans, but current recognition abilities is limited in the qualitative range. This is the same as when a human sees a thing and does not know how long it is, and it will take so long time for AI to evolve beyond humans to have quantitative recognition ability. On the other hand, humankind has developed science and technology by acquiring a quantitative value using a ruler and a scale. Demachi’s laboratory aims to establish new "human" and "object” monitoring by combining AI and non-AI quantitative tools: (1) Maintenance Index & Resilience Index, (2) Early detection of failure of nuclear equipment by AI + statistical processing, (3) Human behavior monitoring by Image recognition AI + Natural Language Processing for Nuclear security and decommissioning labor safety, (4) Visualization of tumor dynamics during radiotherapy using AI + optical flow (AI medical imaging), etc.
Radiation Chemistry Laboratory, Assoc. Prof. Yamashita
Ionizing radiations are closely related to most of issues in nuclear engineering, however, we can utilize their features in cancer therapy, material processing, etc. Their advantages and disadvantages are both sides of the same coin, and are originated from its "individuality". We are investigating fast phenomena induced by ionizing radiations within a microsecond (a millionth second) to reveal their “individuality”. More specific research topics are, for example, as follows:
- Observation of radiation-induced fast phenomena and system development for it
- Radiation effects in nuclear systems
- Initial process of radiation damage to DNA
We try to accept not only the above topics but also others that students are interested in as much as possible.
Applied Laser engineering for controlling atomic systems
We are interested in developing a novel advanced system utilizing single atom control technologies, which are based on atomic, molecular and optical physics. Atoms efficiently absorb photons with energies corresponding to electronic transitions. Difference of the number of neutrons changes the energies of the transitions, which is called isotope shifts. Laser isotope separation is one of the examples making use of such technologies. Photon has also momentum, which can control motion of atoms. Recent progress of the technique, laser cooling, visualizes single atoms. Laser cooling leads atomic ions forming Coulomb crystal of ions. These laser techniques can expand the possibilities of handling nucleus of atoms and molecules. Combinations of Lasers and Isotopes are applicable to not only nuclear engineering, but also medicine, tracer technique, forensic science, and more. We also construct experimental apparatus by ourselves. Let us enjoy Lab life with us!
Accelerator Mass Spectrometry Laboratory
Accelerator Mass Spectrometry (AMS) can detect “Femto-level nuclides” of which isotopic ratio to stable isotope reaches 1E-15 level. Femto-level nuclides are produced by cosmic ray process and artificial nuclear reactions which hold information of paleo environment and materials dynamics in the earth environment. They also are the most clear indicators to define a newly proposed geologic era “Anthropocene” where human being had began to make actual influence to the earth environment. In Matsuzaki laboratory decode various femto-level nuclides’ record in natural archives and environmental samples to discuss the relation between human being and the environment.
Matsuzaki Laboratory is also conducting the development of AMS techniques. Recently we are trying to develop “Laser Photo Detachment” which is totally new technique to separate isobars in which the selective neutralization of negative ions are realized by strong laser utilizing the difference of electron affinity between isobars. If this technique is realized, new Femto-level nuclides such as Ni-59, Sr-90 and Cs-135 could be detected by AMS and we can explore new field in environmental analysis.
Geochemistry of radionuclides and pollutants
It is the duty of our generation to settle the issue of nuclear waste disposal. Geological disposal is the only feasible option for high-level wastes or spent fuels, where various basic research and R&D are still needed. Chemistry of radionuclides is a key foundation to realize a well-accepted disposal project. Thus, we are pursuing understanding and modeling of the chemistry that governs the migration of relevant radionuclides in subsurface environments, which is often called “natural barrier”, using sophisticated spectroscopy, 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 in soils. Any students who has an interest in the issue of nuclear waste disposal are welcomed, no matter what academic backgrounds they have.
Nuclear Instrumentation laboratory – Radiation detection and measurement
We are working on all types of radiation detectors and associated electronics. We create and realize a new idea using the state of the art technologies in microfabrication and advanced electronics. We collaborate with ILL, UCB, TUM, LMU, IAEA, etc. We develop gaseous detectors, scintillation imagers, silicon photomultipliers, superconducting transition edge sensors, flat panel detectors, ASICs, FPGA based systems, PET etc.
Innovative analysis of nuclear material using superconducting radiation sensors
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 to improve 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.
System safety, Maintenance Engineering, Radiation Damage, International Projects
The major focus of our lab is the safety management, maintenance and resilience engineering of complicated systems, the ageing management of nuclear materials, and the promotion of international projects to achieve these. To ensure the safe and long-term operation of nuclear systems, we optimize maintenance practices by risk assessment, and improve the knowledge management for accidents. Besides, we study the irradiation degradation of materials by advanced experimental and modeling methods at multiple scales. Taking advantage of the “Nuclear Safety Management Project” with JAEA, we study the integrated management of nuclear systems, fuel failure, natural hazards, and the management of nuclear waste. We promote international projects with IAEA and OECD/NEA, and send students for internship. Our international research platform connecting the viewpoints from microscale to system scale is ready for you.
Safety Management to cope with unexperienced behavior of complex systems
The design of a safe nuclear system assumes events that have yet to be experienced, such as ageing degradation, natural hazards, and accidents. Deep insight into the physical phenomena involved is required, but it is impossible for a single expert to know every phenomenon in depth. Therefore, the systemic approach to manage the interaction between human, technologies, and organization to improve safety continuously. The technical area of our laboratory is the development of experimental methods to evaluate the effects of complex interactions between materials and radiation to assess the integrity of structural materials and nuclear fuels. Using this area as a starting point, we have been working on the development of methods for integrated risk-informed decision making for improvement of nuclear safety.
Ageing Management and Performance of Nuclear Materials
Ageing degradation of nuclear materials is one of the key issues for the safe operation of nuclear power plants. As an important step to achieve reliable and proactive ageing management of nuclear materials, we combine both experimental and modeling measures to study their ageing mechanisms at multiple scales. Our interests focus on the key materials in reactors, for example core structural materials, reactor pressure vessel steels and fuel cladding materials. State-of-the-art techniques, such as in-situ TEM (Transmission Electron Microscopy) and APT (Atom Probe Tomography), are utilized to observe the evolution of irradiation defects. First-principal modeling is preformed for the comparison with experimental results, and the algorithms for the quantitative analysis of experimental data are also investigated.