| ACHIEVEMENTS IN DEVELOPMENT OF | ||
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| While Fugen kept its stable operation, the concept of self-dependent development, as an enterprising spirit, was also directed to improve plant operation management. It was carried out to develop technologies peculiar to ATR, which ensuing demonstration ATR and even commercial ATRs were taken into account. The technological achievements include development of pressure tube inspection equipment that uses ultrasonic testing and ITV, the establishment of heavy water recycling technology in development of a heavy water upgrader, and protection measures against tritium exposure. Furthermore, collecting, evaluating, and verifying data from experiments, Fugen struggled with the problems common to nuclear plants one by one and established available technologies to LWRs, such as hydrogen injection to counter stress corrosion cracking of stainless steel, and chemical decontamination in the primary cooling system and zinc injection as ultimate solutions for reducing radiation exposure. Those developments were achieved by using full-scale facilities and in cooperation with domestic manufactures. Its accomplishments have been highly evaluated as empirical and reliable technologies that can be widely applied to commercial LWRs. Computer technology, which is quite common nowadays, has been utilized for Fugen's operation since its commencement. Fugen has actively continued to develop the advanced computer system and introduce the technological progress of hardware and software in recent years. The new computer technologies enabled Fugen to systematize techniques of operators and maintenance personnel, which had been considered difficult in the past. Fugen produced results as fuzzy logic controller for the reactor feedwater system that parallels expert operators, operation maintenance control system to try to save labor and improve reliable maintenance, and plant data acquisition system for early detection of abnormal plant condition and analysis of plant behavior. |
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Development of Unique Technologies for ATR |
(1) Pressure Tube Inspection System
Fugen, for the first time in Japan, used a zirconium niobium alloy for material of the pressure tube, which corresponds to the LWR pressure vessel. It was necessary to verify the integrity of the tube by measuring the inside diameter and conducting ultrasonic examination and ITV observation of the inner surface, and to evaluate the validity of the design in the in-service inspection. Therefore, Fugen developed special remote-control automatic inspection equipment designed to be installed in the pressure tube by means of refueling machine. Development was conflictingly demanded for high accuracy in inspections such as high radiation-proof inside the tube and downsizing the unit for installation in the tube. The tests at the O-arai Engineering Center and the trials at Fugen were repeatedly carried out to make improvements, and the equipment currently in use was finally developed. The integrity of the pressure tube and the validation of the design were verified by inspecting with this equipment, and the measurement of creep strain of the pressure tube excellently corresponded to the predicted value. |
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Pressure Tube Inspection Equipment
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