Development of Pressure Tube Inspection Equipment for ATR

None

北原 種道*; 成尾 一輝*; 谷本 健一*

not registered; not registered; not registered

None

A remote-controlled in-service inspection device has been developed for inspecting pressure tubes of the Fugen, which is a heavy water moderated and boiling light water cooled pressure-tube type reactor. The equipment is capable of performing three kinds of inspections ultrasonic flaw detection; measurement of inside diameter; and visual inspection of the internal surface. To reduce the radiation exposure of inspectors, the three kinds of detectors, with their associated electronics and drive mechanisms for vertical and rotating movements, are housed in the inspection tool assembly, which can be mounted on or removed from the pressure tubes by a refueling machine through remote control operation. The ultrasonic technique has been adopted for measurement of the internal diameter in order to shorten the inspection time. Detectors, TV camera, and electronic components used in the inspection tool assembly were selected on the basis of irradiation test results. Before inspection of the Fugen reactor, the total system was tested on a mock-up pressure tube to confirm its functions, performance, durability and reliability. Test results are; (1)The ultrasonic flaw detector can detect an artificial flaw of 2.0mm in lengthg, 0.1 mm in width and 0.1 mm in depth with S/N=7dB; (2)The inside diameter measurement system can measure the inside diameter, ranging from 117,5mm to 119.5mm, to an accuracy of 20m; (3)An artificial flaw of 2.0mm in length, 0.1 mm in width and O.1mm in depth can be observed by the internal surface observation system. The equipment was used for the inspection of ten pressure tubes of the Fugen reactor during the May 1984 annual inspection. No degradation of the performance of the equipment was observed even after 55 hours of inspection under a maximum dose rate of 2.510R/h. Based on these results, the functions and performance of the equipment in practical use were fully confirmed.