Abstract: The use of portable and high-energy x-ray system can provide a very promising approach for the inspection of aged concrete structures. However, due to the effect of large scattering of low-energy x-ray in a thick concrete, the noise properties and contrast of the radiographic images need to be optimized to ensure reliable interpretation. Therefore, in order to improve the inspection ability, an image denoising method with the combination of wavelet and curvelet transform and image contrast e...
英字タイトル:
Image Enhancement for Concrete Bridge Inspection with Portable 950 keV/ 3.95 MeV X-ray Source

In power plant, the operator monitors measured values of many installed sensors for operation and maintenance. Since the number that can be visually confirmed is limited, we have proposed two-stage autoencoder for anomaly detection. The latest version was developed to suppress false positives due to spurious correlations in training data, and its effectiveness was shown using simulation data. In this paper, the anomaly detection performance is shown using the operational data of an actual power plant. As a ...
英字タイトル:
Performance Evaluation of the Anomaly Detection by Two-Stage Autoencoder using Power Plant Data

Seal welding is a repair method when crack by Stress Corrosion Cracking (SCC) is found in weld rtion of core internals including pressure b oundary component in nuclear power plant. Seal lding is welded directly on surface of existing SCC crack and prevents SCC propagation by la ting SCC crack from reactor water environment. In this study, development of seal welding hnology using automatic TIG Welding was executed, and the applicability of seal welding method CRD stub-tube weld portion was confirmed by ex...
英字タイトル:
Development of Seal Welding Repair Technology for CRD Stub-tube

The JMTR is under the refurbishment and will start on FY 2011. The JMTR will operate for about 20 years from 2011. Before this JMTR operation, preliminary inspection of seconda ry cooling system piping was carried out in order to make a maintenance plan.As the resu lts of this inspection, it was confirmed that the corrosion was reached by piping ingot, or decrease of piping thickness could hardly be observed. Therefore, it was confirmed th at the strength or the functionality of the piping had been mai...
英字タイトル:
Preliminary Inspection of Secondary Cooling System Piping for Maintenance Plan in JMTR

Abstract: Since more and more bridges built several decades ago in Japan have become aged and dangerous, the non-destructive evaluation of those bridges is really an urgent problem. CT system with portable 3.95MeV linacs for bridge inspection is considered to work on-site, considering the law of Japanese radiation protection allows using linacs up to 4MeV outside radiation controlled area. The system would confirm the internal steel si tuation of bridges and analyze structural strain and stress with 3D mod...
英字タイトル:
On-Site Bridge Inspection with Partial CT by 3.95Mev X-Band Linac Source

In situ CT application for NDE of degradation bridges is under development, with portable 950keV/3.95 MeV X-band linac as x-ray source. Collimator is adopted to reduce scattered X-ray noise. Material analysis and erosion estimation through dl-energy CT method is integrated in order to inspect the erosion situation of i nner steel rod. Reconstruction technique with incomplete projection data is studd considering limitation of projection angle range during onsite scanning. Furt hermore, based on 3D model bui...
英字タイトル:
Partial Inspection and Dual-energy CT Material Analysis with 950keV/3.95MeV X-Band Linac

A probabilistic analysis code PASCAL-EC (PFM Analysis of Structural Components in Aging LWR - Erosion and Corrosion) has been improved for evaluating structural integrity of wall-thinned pipes on the basis of the Monte Carlo method. In order to perform the fragility evaluation for wall-thinned pipes, several functions are introduced to PASCAL-EC in this work, such as a probabilistic evaluation model to consider the uncertainty of seismic response stress, a simple evaluation model to considered the incr...
英字タイトル:
Fragility Evaluation of Wall-thinned Pipes Using PASCAL-EC

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

This study proposes numerical analysis model considering grain boundary slip and microscopic h eterogeneity in order to estimate stress distribution which effect crack initiation and propaga tion. The FEM-MD combined method for considering grain boundary slip is discussed. The estimat ion of mechanical properties for taking account of microscopic heterogeneity is also discussed....
英字タイトル:
Development of Numerical Analysis Model considering Grain Boundary Slip and Microscopic Heterogeneity for the Evaluation of Crack Initiation and Propagation

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