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Nishio S.,Wakasa - Wan Energy Research Center
Corrosion Science | Year: 2012

Zr metal readily dissolved in a mixture of H 2SO 4 and HNO 3. The solubility of Zr in a 10% mixture (96wt% H 2SO 4:61wt% HNO 3=9:1 volumetric mixture) reached approximately 34g/L. It was found that NO2+ and H 2SO 4 are consumed to form NO 2, NO +, and HSO4- upon the dissolution of Zr. Finally, two possible dissolution mechanisms are discussed. © 2012 Elsevier Ltd. Source


Tane M.,Osaka University | Mayama T.,Kumamoto University | Oda A.,Osaka University | Nakajima H.,Osaka University | Nakajima H.,Wakasa - Wan Energy Research Center
Acta Materialia | Year: 2014

The tensile and compressive deformation in porous Mg with unidirectionally oriented cylindrical pores and a unique fiber texture in which the normal direction of the {1 0 1¯ 3} plane was preferentially oriented was studied. Porous Mg specimens with unidirectional pores and texture were prepared by unidirectional solidification in a hydrogen atmosphere using a continuous-casting technique and their quasi-static tensile deformation and quasi-static and dynamic compressions were investigated. In tensile loading parallel to the orientation direction of the pores (the "pore direction"), the porous Mg exhibited a large tensile elongation of ∼60% strain despite the presence of ∼42% porosity, whereas it showed high energy absorption of ∼30 kJ kg-1 along the same direction. To clarify these superior mechanical properties, the underlying operative deformation modes and rotation of crystallographic orientation during loadings were analyzed by X-ray pole figures, optical microscopy and crystal plasticity finite-element modeling. The analyses revealed that in the initial stage of both the compression and tensile loadings along the pore direction, basal slip mainly operated. Importantly, the activity of basal slip was enhanced during the tensile loading by rotation of the crystallographic orientation, which resulted in high tensile elongation. On the other hand, the activation of basal slip was initially suppressed by the crystal rotation during compression. However, the localization of basal slip originating from the elongated grains with the unique texture subsequently enhanced the activity of basal slip, which suppressed the steep increase in the flow stress. This unique localized deformation gave rise to the superior impact energy absorption. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Source


Fekete T.,Wakasa - Wan Energy Research Center
Frattura ed Integrita Strutturale | Year: 2016

In Hungary, four nuclear power units were constructed more than 30 years ago; they are operating to this day. In every unit, VVER-440 V213-type light-water cooled, light-water moderated, pressurized water reactors are in operation. Since the mid-1980s, numerous researches in the field of Pressurized Thermal Shock (PTS) analyses of Reactor Pressure Vessels (RPVs) have been conducted in Hungary; in all of them, the concept of structural integrity was the basis of research and development. During this time, four large PTS studies with industrial relevance have been completed in Hungary. Each used different objectives and guides, and the analysis methodology was also changing. This paper gives a comparative review of the methodologies used in these large PTS Structural Integrity Analysis projects, presenting the latest results as well. © 2016 Gruppo Italiano Frattura. All Rights Reserved. Source


Fekete T.,Wakasa - Wan Energy Research Center
Frattura ed Integrita Strutturale | Year: 2016

Buildings, structures and systems of large scale and high value (e.g. conventional and nuclear power plants, etc.) are designed for a certain, limited service lifetime. If the standards and guidelines of the time are taken into account during the design process, the resulting structures will operate safely in most cases. However, in the course of technical history there were examples of unusual, catastrophic failures of structures, even resulting in human casualties. Although the concept of Structural Integrity first appeared in industrial applications only two-three decades ago, its pertinence has been growing higher ever since. Four nuclear power generation units have been constructed in Hungary, more than 30 years ago. In every unit, VVER-440 V213 type light-water cooled, light-water moderated, pressurized water reactors are in operation. Since the mid-1980s, Pressurized Thermal Shock (PTS) analyses of Reactor Pressure Vessels (RPV) have been conducted in Hungary, where the concept of structural integrity was the basis of research and development. In the first part of the paper, a short historic overview is given, where the origins of the Structural Integrity concept are presented, and the beginnings of Structural Integrity in Hungary are summarized. In the second part, a new conceptual model of Structural Integrity is introduced. In the third part, a brief description of the VVER-440 V213 type RPV and its surrounding primary system is presented. In the fourth part, a conceptual model developed for PTS Structural Integrity Analyses is explained. © 2016 Gruppo Italiano Frattura. All Rights Reserved. Source


Kurita T.,Wakasa - Wan Energy Research Center
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2014

I developed a beam current transformer (CT) for monitoring the beam of a slow-cycling accelerator. The beam monitor is a new type of CT that measures the average current of a circulating beam using a negative impedance circuit (NIC). Adding an NIC can extend the low-frequency cutoff of a CT down to 0 Hz (Ninomiya et al., 2006 [1]). This report presents the detail of our proposed beam-monitoring system. The measurable band width of the CT is 30 kHz. The stability of the droop time constant of the square pulse response is ~2%/s. This beam monitor was developed for the synchrotron at the Wakasa-Wan Energy Research Center (WERC) and is currently installed there. © 2014 Elsevier Ltd. All rights reserved. Source

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