Fig. 7-1 Outline of Studies on Reactor Physics and Engineering

Table 7-1

Reactor Physics and Engineering Research Themes Fundamental studies related to reactors are being conducted to support nuclear technology.

Development of Tandem Accelerator System Evaluation Study of Atomic and Molecular Data Study on Fast Reactor Physics Experimental Study on Accelerator Driven TRU Incineration System Study on Reactor Control and Diagnostics Study on Radiation Shielding Study on Fusion Neutronics Engineering Study on Long-Lived Radioactive Waste Incineration System Study on Free Electron Laser Evaluation Study of Nuclear Data Study on Characteristics of Reactor Systems Study on Thermal Reactor Physics Study on Sensing Technology Study on Remote Control Robotics for Reactor Applications Study on Reactor Thermohydraulic Engineering Study on Passive Safety Reactor Development of Intense Proton Linear Accelerator

Nuclear power is growing to be one of the major energy sources of the world. However, the possibility of an accident is increasing as the number of power reactors increases in many countries including developing ones. The utilization or disposal of plutonium and radioactive waste accumulated during the operation of power reactors is also a big problem. To solve these problems, studies in the field of reactor physics and engineering are being pursued. An outline of these studies is shown in Fig. 7-1. These activities include studying new reactor concepts, developing software to support reactor core design, performing reactor physics experiments, and compiling evaluated nuclear data and information on advanced reactor engineering technologies. New reactor concepts under consideration are; A passive safety light water reactor that reduces the possibility of failure during operation by utilizing natural forces and simplifies operation and control by using less complex systems. A plutonium burner reactor utilizing rock like fuel that requires no processing of discharged fuels. An active storage light water reactor with a large inventory and a small consumption of plutonium. A closed fuel cycle employing a nitride fuel fast reactor coupled with dry processing to enhance safety and economy. Space reactors for space propulsion and for powering a lunar base. Several design support software programs are under development.One is an intelligent reactor design system, IRDS, that can be used by even a non- specialist who has a new idea for the design of a reactor. The other is a highspeed, high accuracy Monte Carlo code program to solve reactor physics parameters of systems having complicated geometry. Reactor physics experiments are being performed to validate the characteristics of new-concept reactors and to enhance the prediction accuracy of safety characteristics by measuring data such as the Doppler effect at high temperature. This series of experiments will provide data for fast reactors, high-temperature gas cooled reactors, light water reactors using plutonium fuel,fusion reactors, and accelerator driven TRU incineration systems. Version 3.2 of the evaluated nuclear data file, JENDL, developed at JAERI, is under modification to enhance the design accuracy for light water reactors, fast reactors, and fusion reactors. The file is utilized not only for neutronics but also for radiation shielding. A series of JEAMDL files that compile atomic and molecular data are also being accumulated to analyze fusion plasma phenomena. Among the studies to develop advanced reactor engineering technologies, effort in the field of reactor control is focussed on a total system control concept based on a new control theory, a diagnostics technology based on noise analysis, and a robotics technology for decommissioning and more complex tasks.In the field of instrumentation, work is ongoing to develop a new-type in-pile neutron detector, a nondestructive techique to measure radiation degradation of reactor components, a particle detector system for an accelerator, a portable system for environmental radiation measurements, and a nondestructive method to detect TRU contained in waste drums. In the field of heat transfer and fluid flow, an analytical study that focusses on nominal and accident conditions is underway. A technique to accelerate heat transfer in an accelerator target is also being studied.

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