稲田 崇 Takashi INADA Water Jet Peening (WJP) has been widely applied to Japanese nuclear power plants since 1999, as an approved mechanical mitigation technique against stress corrosion cracking (SCC) on materials use d for nuclear reactors.Existing laboratory experience and analysis indicated that WJP had no negative impact on pre-existing cracks, such as crack propagation during its application, although ther e was no field experience of applying WJP on cracked surfaces. Recently, The Japan Atomic Power C...
英字タイトル:
APPLICATION OF WATER JET PEENING ON BWR REACTORINTERNALS WITH CRACKED SURFACES

WJP (Water Jet Peening) technology generates the compressive residual stresses on the surface of the material by the extremely high impulse pressure caused by the collapse of cavitation bubbles when high-pressure water jet is discharged in the water. WJP is the promising technology for countermeasure of SCC initiated on the core structures of BWR with some advantages; Collection of foreign materials is not necessary, and WJP is applicable to the complicated structure in narrow space and improves relat...
英字タイトル:
Application of Water Jet Peening (WJP) technology to BWR Core Support Structures

In this paper, experimental and numerical studies are carried out to understand the pipe-wall thinning caused by the flow accelerated corrosion behind an orifice in a circular pipe. The measurement of mass transfer coefficient is carrie d out using a wall material of benzoic acid in a water flow, which allows the measurement of mass transfer behind the orifice in a circular pipe at Schmidt number 300 and 700, which is comparatively close to the actual condition in the prototype pipeline of nuclear power pl...
英字タイトル:
Study on Mass Transfer Phenomenon behind an Orifice in a Circular Pipe - Effect of Schmidt Number -

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....
英字タイトル:
Development of inspection method for thinned bolts by PA-UT

One year has passed since Electronic Journal of Advanced Maintenance (EJAM) was started on the website of Japan Society of M aintenology (ISM) May 25“, 2009. “New Technology' (NT) is one of the EJAM categories, and introduces widely advanced techniqu es developed or modified for maintenance. Twenty-two NT articles have been introduced on EJAM website so far as of May 25t“, 2010. This report describes the concept of NT, general features of NT articles, actual performance and future wishes for NT....
英字タイトル:
Current Status of EJAM ‘New Technology

This study is considering the effect of clamp conditions on welding deformation and residual st ress distribution. Welding deformation and residual stress becomes initial imperfections, and i t causes structures weak so it must be controled. The result of numerical analysis shows that an appropriate conditions should be chosen by considering welding distortion and residual stress....
英字タイトル:
Effect of condition of clamp on deformation and residual stress in welding

Abstract In this study, we focused on the singular weld residual stress distribution could be seen when we evaluated by X-ray dif fraction method. We used specimens welded under two heat input conditions, and so the weld metal of each specimen had a different solidification structure. In the specimen that had martensite in weld, the weld metal showed a clear difference between the resi dual stresses in longitudinal direction and transverse direction. However, in the specimen that had bainitic-ferrit in wel...
英字タイトル:
Evaluation of residual stress in weld metal by X-ray diffraction method in consideration of the anisotropy of the X-ray elastic constant

This paper introduces the applied experience of Inspection and Evaluation Guideline for Japanese BWR plants' core shroud. This report includes the compari son of evaluation performed by using Guideline's method and actual inspection results for several plants. Evaluation was performed at the time when SCC wa s found. After one cycle operation, actual inspections were done to confirm the amount of existing crack growth. It was confirmed that actual crack growth is less than predicted value by the evaluation...
英字タイトル:
Applied experience of Inspection and Evaluation Guideline to actual BWR internals

Stress corrosion cracking of welding portion has found in many domestic and foreign BWR reactor internals and Primary Loop Recirculation piping. Also, repair and preventive maintenance technologies for SCC has been developed and/or adopted to BWRs in recent years. This paper introduces the sample of these technologies, such as seal-welding fo r SCC on BWR reactor internals, preventive maintenance technology for PLR piping such as Corrosion Resistant Cladding, Internal Polishing and Induction Heating Stress...
英字タイトル:
Repair and Preventive maintenance Technology for BWR Reactor Internals and Piping