The SCC susceptibility of the weld metal was evaluated from the maximum depth and number of cracks occurring during the CBB (Creviced Bent Beam) test in high temperature pressurized water using plate specimens cut from shielded metal arc weld metals. When the specimen received a heat treatment consisting of stress relief annealing (SR) for 72 ks at 893 K and subsequent ageing (LTA) for 720 ks at 673 K, however, the significant influences of the increases in C and Nb contents on the SCC susceptibility were...
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Effects of C and Nb Contents on Stress Corrosion Cracking of Shielded Metal Arc Weld Metalfor 600 Type Alloy in High Temperature Pressurized Pure Water

Fiber Bragg Grating（FBG）is a kind of an optical device developed rapidly in these years and it has several excellent characteristics as a sensor for tempera- ture and/or strain. To investigate the applicability of FBG even as a vibration sensor for nuclear plant monitoring, novel measurement systems were devel- oped and tested. The results revealed that the FBGs had sensitivity to vibration and temperature even in radiation environments. Vibration and/or temperature of components around cooling system...
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Applicability of a sensor based on optical fiber Bragg grating to nuclear plant monitoring

Many anchor bolts have been used for fixing many components in nuclear power plant (NPP), securing safety against seismic ev ents. Some methods have been developed to detect crack-like defects in bolts which may occur after seismic events. On the ot her hand, assuming long term use of NPP, a method to detect bolt thinning was thought to be needed. In this study, by using bolt specimens with an artificially grinded portion, a new method to detect thinning and to measure its depth was developed....
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Development of inspection method for thinned bolts by PA-UT

In this study, the effects of seal welding conditions, such as welding heat input, depth of crack, and plate thickness, on the welding-induced residual stress and the stress intensity factor (SIF) around the remaining crack were investigated by finite element analysis. In addition, the parameter Q/√a (Q: welding heat input, a: depth of crack) was theoretically derived from welding thermal conduction theory as representative of the temperature distribution along the crack direction. As the results, it w...
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Study on Welding Procedure Parameter Influencing Structural Soundness at Seal Weld

The aim of this study is to research and evaluate new technologies i n the world from the point of view to improve the safety and securi ty of pipeline for gas distribution toward the next generation which can practice the productive maintenance and preventive maintenance....
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Research and Evaluation of New Technologies to Improve the Maintenance of Pipeline for GasDistribution toward the Next Generation

The aim of this study is to research and evaluate new technologies in the world from the point of view to improve the safety and security of pipeline for gas distribution toward the next generation which can practice the productive maintenance and prevent ive maintenance. ...
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Research and Evaluation of New Technologies to Improve the Maintenance of Pipeline for GasDistribution toward the Next Generation

The purpose of this study is to develop underwater High-Definition camera for the confirmation test of core configuration and visual examination of BWR f uels in order to reduce the time of these tests and total cost regarding to purchase and maintenance. The prototype model of the camera was developed and examined in real use condition in spent fuel pool at HAMAOKA-2 and 4. The examination showed that the ability of prototype model was either equaling or surpassing to conventional product expect for resi...
英字タイトル:
Development of underwater High-Definition camera for the confirmation test of core configuration andvisual examination of BWR fuel

The degradation of 1-nozzle type Jet Pump (JP) efficiency by crud deposition has been recognized in some BWRs. In order to remove crud, we must clean each o r all of JP inner surface. The increase in cleaning surface area induces the increase in outage period and cost, therefore, in the previous study we looked for the most effective cleaning portion at inner surface for efficiency recovery. In this study, for the 5-nozzle type JP, we evaluated the effect of crud portion on decrease in efficiency of 5-noz...
英字タイトル:
Studies on Recovering Method of 5-nozzle type Jet Pump Efficiency