In recent years, according to the progress of global warming, hurricanes and typhoons getting bigger and bigger, about 20% increase per decade. Hurric anes and typhoons are given thermal energy from vaporizing steam from surfe of sea water. Hurricane Sandy attacNed New YorN on 22-29, Oct. 2012. Ty phoon 26th attacNed Ohshima, Oct. 2013, and Typhoon 30th attacNed Philippine on Nov. 4-11. Tropical cyclone Phailin attacNed India on Oct. 12, 2013. I ts diameter was 2300Nm. They were all category 5. Human being...
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Necessity of Countermeasures for Hurricane, Typhoon and Cyclone in Accordance with the Progress of Global Warming

By evaluating the phenomena that hydrogen concentration of outlet gas in the off-gas treatment system at Hamaoka Unit 4 and 5 had increased, it was con cluded that the causes of the phenomena were transformation of support alumina by alteration of manufacturing process of catalysts and the deactivation by catalyst poisoning material. Therefore, the manufacturing process was modified and the poisoning material was identified and removed. Moreover, dev elopments such as catalyzer performance monitoring techn...
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Study of Degradation of Off-Gas H2/02 Recombination Catalyst at Hamaoka Unit 4 and 5 Hiroyasu OOSUMI

Abstract Adverse events that have occurred at overseas nuclear power plants can be studied to provide an indication of how to improve the safety and the reliability of nuclear power plants in Japan. The Institute of Nuclear Safety Systems (INSS) obtains all information related to overseas adverse events and incidents at power stations, evaluates them in an attempt to prevent similar occurrences in Japanese PWR plants, and proposes recommendations to Japanese PWR utilities. Through su ch INSS evaluation act...
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Analysis of Tendency on Adverse Events Occurred at Overseas Nuclear Power Plants in 2003

The high level maintenance technology has become necessary to increase a capacity factor of nuclear power plants. In a nuclear power plant, There are various kinds of troubles concer ning with pipes. One of them is a small leak from a small hole by liquid drop impingement erosion (LDIE). Even such a small leak, it was sometimes a cause of the plant trip and an eco nomical losses about 200M$ during several month outage, by operating a 1000MWe fossil power plant. We conducted a LDIE test by using a test spec...
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Pipe Wall wastage by Liquid Droplet Erosion and It's Countermeasure

Evaluation of wastage speed for nuclear power plant maintains plant reliability and power up rating is important. There are two main cause of wastage flow accelerated corrosion (FAC) and mechanical erosion. This study is to develop evaluating the wastage speed by liquid droplet impingement erosion (LDIE). LDIE oft en occurs at downstream of corner of pipe or orifice. In this study, the liquid drop impinging tests were conducted with the test pieces mounted on a high speed rotating disk that cross thin wate...
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Study on pipe wastage mechanism by Liquid Droplet Impingement Erosion

Abstract An eddy current testing (ECT) system has been developed for inspecting weld surfaces of components in the reactor pressure vessel of nuclear plants. The system can be applied to curved surfaces with an ECT array probe, it can discriminat e flaws from other signal factors by using a combination of arrayed coils signal-phase. The system is applied to a mock-up of core internal components and the signal discrimination using the signal-phase clearly separated flaw and noise signals....
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Surface Inspection Technique with an Eddy Current Testing Array Probe

Since the accident at Fukushima Daiichi Nuclear Power Station of the Tokyo Electric Power Company, reconstruction work at Fukushima has needed to deal with high radiation environments and has demanded new technologies. This requires the development of remote-controlled robots capable of rubble removal, radiation measurement, and other technologies, as well as ways of utilizing these technologies in tandem. It is also necessary to conduct a site survey (including the visual assessment, identification of...
英字タイトル:
Development of remote-controlled robot technology for the Fukushima Reconstruction

To verify the effect of hardened surface on stress corrosion cracking (SCC) of 316L, characteristics of cracked BWR core shroud have been investigated by means of microstructures. At the inner surface of core shroud where grinding was done, fine grains were observed at the surface thin layer. Furthermore, deformation-induced slip-line field including extensive deformation-twins was observed in the harden ed surface region. In contact with corrosion products on the shroud surface, intensive Ni enrichment a...
英字タイトル:
Microstructural Analyses of hardened surface in BWR core shroud made of 316L

In this study, we propose a novel EMAT-ECT multi sensor aiming at advanced structural health monitoring. For the purpose, proto-type EMAT-ECT multi-sensor was developed and their functions both as ECT and EMAT prove were evaluated. Experimental results of pulse ECT using the EMAT-ECT multi-sensor showed that the pr oposed sensor has a capability of detection and sizing of flaws. Experimental results of EMAT evaluation using the EMAT-ECT multi-sensor showed that ultrasoni c wave was transmitted by EMAT-ECT ...
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Development of novel EMAT-ECT multi-sensor and verification of its feasibility

Abstract Structural health monitoring (SHM) techniques are needed to maintain the reliability of power plants for long term operation. The high temperature transducers are necessary to realize SHM (monitor wall thickness of the pipings, crack growth in the materials and material evaluation) under the working condition of power plants. We have evaluated lithium niobate (LiNb03) single crystal which is well known as a high Curie temperature piezoelectric material to develop high temperature ultrasonic transd...
英字タイトル:
Development of High Temperature Ultrasonic Transducers