A Ni-base alloy weld, including cracks due to stress corrosion cracking found in the reactor internal of the oldest BWR in Japan, Tsuruga unit 1, in 1999, was examined by three (3) types of UT method. After this examination, a depth of each crack was confirmed by carrying out a little excavation with a grinder and PT examination by turns until each crack Hisappeared. Then, the depth measured by the former method was comp ared with the one measured by the latter method. n this fashion, performances of the ...
英字タイトル:
Evaluation on Ultrasonic Examination Methods applied to Ni-base Alloy Weld including Cracks dueto Stress Corrosion Cracking found in BWR Reactor Internal

Tohoku Electric Power Co., Ltd. plans to continuously improve its safety, based on high-quality risk management. Tn the risk management framework, quantification of risk by PRA plays an important role. Here, we introduce the status of our efforts to improve our PRA method, such as refined internal event level l PRA models, improved data, and the expanded scope of PRA....
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Tohoku Electric Power's efforts to improve PRA method

Stainless steel is used in various nuclear installations as a major structural material. Tritium is produced by several nuclear reactions in these facilities. It is considered that the hydrogen isotope included tritium permeated for stainless steel through the interaction such as dissolution, diffusion and recombination, and is released on the atmosphere. Therefore, it is important to clarify permeation behavior of tritium in stainless steel from the viewpoint for improvement of the social acceptability o...
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Study on permeation behavior of hydrogen isotope in stainless steel

Tritium from the nuclear power plants should be monitored at real-time. The development of real-time atmospheric tritium monitor is an important issue, since it was reported that tritium from the nuclear power plants was released as the form of HT and HTO, and released tritium was adsorbed plants and transported to numan through photosynthesis and food chain processes. This study was carried out to develop the separation-condensation technique for tritium using polyimide hollow fiber module. At first, ion ...
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Research and development of real-time atmospheric tritium monitor by polyimide hollow fiber

強度試験に用いる鋼材を原子炉内の限られたスペースで中性子照射させる必要から、小型試験片による試験技術は原子炉圧力容器の監視試験のキー技術であり、継続して開発が続けられてきた。当所で開発と実用化を目指してきた試験技術から、現行の監視試験片の1/8以下の大きさで破壊靭性を評価できる技術と、直径8mm、板厚0.5mmという小型円板でと引張強度特性を評価する技術を紹介する。 ...

Electro-Magnetic Induction Testing method is widely used in the industries. However, due to the deterioration of sensitivity by increase of Lift-Off (distance between sensor and test piece) and the limitation of penetration of magnetic flux into thick magnetic and conductive material such as carbon steel, its application is limited to comparative testing between sound and defective samples. The newly developed system enables the measurement of wall thickness and the detection of inner-surface defects ...
英字タイトル:
Development of Measuring Techniques of Thick Wall Samples by Electro-Magnetic Induction (Part 1) - An Application for Pipes covered by Thermal Insulator -

Eddy Current Testing (ECT) is widely used in the industries. However, ECT normally uses certain high frequency range, therefore its application is limited to detect surface- or near surface defects. Strength of the electro-magnetic flux decreases exponentially in penetrating into the samples, and its rate is a function of conductivity, permeability and thickness of the samples and the frequency in use. Therefore, conventional ECT is difficult to detect inner surface defects or measure the thickness of...
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Development of Measuring Techniques of Thick Wall Samples by Electro-Magnetic Induction (Part 2) - An Application for Vessels with Heating Jacket -

It is known that weld distortion has negative influence on structure integrity. Therefore, it is important for ensuring structure strength and reliability to control weld distortion appropriately. Especially, development of various countermeasures against weld distortion is desirable for emergent repair work in large-scale accident such as earthquakes. As one of useful countermeasure against angular distortion, in-process control welding with reverse-side heating was proposed however validation of the ...
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Study on Shape Regulation Technique of Weld Structure for Good Quality Control

A Ni-base alloy weld, including cracks due to stress corrosion cracking found in the reactor internal of the oldest BWR in Japan, Tsuruga unit 1, in 1999, was examined by three (3) types of UT method. After this examination, a depth of each crack was confirmed by carrying out a little excavation with a grinder and PT examination by turns until each crack disappeared. Then, the depth measured by the former method was compared with the one measured by the latter method. In this fashion, performances of...
英字タイトル:
Evaluation on Ultrasonic Examination Methods applied to Ni-base Alloy Weld including Cracks due to Stress Corrosion Cracking found in BWR Reactor Internal