[en] The helium engineering demonstration loop (HENDEL) consists of the first and second helium loops (M₁ and M₂ loops) and six test sections, the first of which was completed and the others to be designed. This report describes operational data of components (heater, blower and cooler) and overall performance of the first loop (M₁ loop), during the test operation until March 1983. Finally M₁ loop was comfirmed to be able to provide He gas of 450⁰C, 0.4 kg/s and 4.0 MPa to the fuel stack test section (T₁). (author)

[en] In case that the nuclear power station is surrounded by the complicated terrain (e.g. mountains), the diffusion condition of effluent gas emitted from the stack is influenced by it. In order to estimate this influence, making a wind tunnel experiment with a terrain model and comparing the results with those under a flatland condition, we evaluate the effective stack height to calculate the exposure dose. This report presents a summary of the wind tunnel experiment on stack gas diffusion for Shimane Nuclear Power Station, the estimation of exposure dose with the results, and its utilization for the emergency planning. (author)

[en] Nuclear power plants require a distributed control system to ensure a high ratio of reliability to cost. This paper proposes a flexible configuration control system which is both reliable and economical. This system is capable of continuous plant control owing to a back-up function performed by individual adjacent controllers, even if several controllers fail. To evaluate the system, formulas of Mean Time To Failure (MTTF) and MTTF/redundancy which include the degree of meeting the requirement of control function are prepared as indices of reliability and cost performance respectively, based on the concept of system function reliability. Calculation results clarify that these indices are higher than those of the triple system or n:1 back-up system. (author)

[en] Summary Meeting on Nuclear Fusion Research by Grant-in-Aid (1980--1982) of Monbusho has been held at Gakushikaikan and Josuikaikan, Tokyo, in Aug. 23--25, 1983. More than 200 papers included the research activities in the following seventeen subjects have been presented. I. Reactor Materials and Plasma-wall Interactions ; 1. Heavy irradiation effects, 2. Plasma-wall interactions, 3. Neutronics, 4. Welding engineering II. Science, Technology and Biological Effects of Tritium ; 1. Science and technology of tritium, 2. Biological effects of tritium III. Fundamentals of Reactor Plasma Control ; 1. Diagnostics of high-temperature plasmas, 2. New drivers, 3. Fundamentals of plasma heating, 4. High-efficiency energy conversion, 5. Theory and computer simulation IV. Technology of Superconducting Magnet; 1. Superconducting magnet materials, 2. Fundamental phenomena of superconductivity, 3. Magnet technology V. Design and Evaluation of Fusion Reactor ; 1. Heat transfer and structural engineering, 2. System design, 3. Resources and assessment of fusion energy (author)

[en] A new reacting plasma machine is designed, and will be constructed at the Institute of Plasma Physics, Nagoya University. It is important to avoid the activation of the materials for the machine, accordingly, aluminum alloy has been considered as the material since the induced activity of aluminum due to 14 MeV neutrons is small. The vacuum chamber of the new machine consists of four modules, and the remote control of each module is considered. However, the cost of the remote control of modules is expensive. To minimize the dependence on the remote control, the use of aluminum alloy is considered as the first step. The low electrical resistivity, over-ageing, weak mechanical strength and eddy current characteristics of aluminum alloy must be improved. The physical and electrical properties of various aluminum alloys have been investigated. Permeability of hydrogen through aluminum, the recycling characteristics and surface coating materials have been also studied. (Kato, T.)

[en] Recently, the design of fusion reactors such as Intor has been carried out, and various properties that fusion reactor materials should have been clarified. In the Japan Atomic Energy Research Institute, the research and development of materials aiming at a tokamak type experimental fusion reactor are in progress. In this paper, the problems, the present status of research and development and the future plan about the surface materials and structural materials for the first wall, blanket materials and magnet materials are explained. The construction of the critical plasma testing facility JT-60 developed by JAERI has progressed smoothly, and the operation is expected in 1985. The research changes from that of plasma physics to that of reactor technology. In tokamak type fusion reactors, high temperature D-T plasma is contained with strong magnetic field in vacuum vessels, and the neutrons produced by nuclear reaction, charged particles diffusing from plasma and neutral particles by charge exchange strike the first wall. The PCA by improving 316 stainless steel is used as the structural material, and TiC coating techniques are developed. As the blanket material, Li₂O is studied, and superconducting magnets are developed. (Koko, I.)

[en] In order to obtain the optimum conditions for micro-hardness measurements of sintered UO₂, two kinds of hardness tests (Vickers and Knoop) were examined with non-irradiated UO₂ of 2.5 and 5 μm in grain size. The hardness values were obtained as a function of the applied load in the load range of 25 -- 1,000 g. In the Vickers test, cracks were generated around the periphery of an indentation even at lower load of 50 g, which means the Vickers hardness is not suitable for UO₂ specimens. In the Knoop test, three stages of load dependence were observed for sintered pellet as well as for a single crystal by Bates. Load dependence of Knoop hardness and crack formation were discussed. In the range of applied load around 70 -- 100 g there were plateau region where hardness values were nearly unchanged and did not contain any cracks in the indentation. The plateau region represents a hardness of a specimen. From a comparison between the hardness values of 2.5 μm and those of 5 μm UO₂, it was approved that the degree of sintering controls the hardness in the plateau region. (author)

[en] In the Central Research Institute of Electric Power Industry, the Nuclear Information Center was established for the purpose of raising the rate of plant operation of nuclear power stations by utilizing the experience and information in nuclear power plants. In the center, in addition to the statistical analysis of the information and the analysis of the individual items of information, the preventive maintenance aid system is now under development. These activities are described, and also the information transmission system ''NOTEPAD'' of the (U.S.) Institute of Nuclear Power Operations, from which the center derives the information. In the preventive maintenance aid system, ''abnormal phenomena'' are inputted to the system, then, the phenomena inferred from them, and expanding and spreading phenomena are outputted, and along with these, the recommended countermeasures are given. (Mori, K.)

[en] Recently in the field of scientific and technical calculation, the usefulness of supercomputers represented by CRAY-1 has been recognized, and they are utilized in various countries. The rapid computation of supercomputers is based on the function of vector computation. The authors investigated the adaptability to vector computation of about 40 typical atomic energy codes for the past six years. Based on the results of investigation, the adaptability of the function of vector computation that supercomputers have to atomic energy codes, the problem regarding the utilization and the future prospect are explained. The adaptability of individual calculation codes to vector computation is largely dependent on the algorithm and program structure used for the codes. The change to high speed by pipeline vector system, the investigation in the Japan Atomic Energy Research Institute and the results, and the examples of expressing the codes for atomic energy, environmental safety and nuclear fusion by vector are reported. The magnification of speed up for 40 examples was from 1.5 to 9.0. It can be said that the adaptability of supercomputers to atomic energy codes is fairly good. (Kako, I.)

[en] In experimental fast reactor ''JOYO'', natural circulation test with a trip of all main pumps in the 75MW full power operation was conducted on December 23, 1981. Transition of the main loop flow from forced flow to natural circulation was smooth, and high natural circulation capability was verified. The peak fuel subassembly outlet sodium temperature during this test was below that during 75MW normal operation. Previous to the test, natural circulation analysis code MIMIR- N2 was developed. The predicted peak value of the fuel subassembly outlet sodium temperature was in a good agreement with the measured value. (author)