[en] Thermal aging of several duplex stainless steels was detected by an ultrahigh sensitive magnetic sensor using superconducting quantum interference device (SQUID). It was found that the SQUID output signal pattern in the presence of AC magnetic field applied to the specimen was sensitive to very small amount of material property changes due to thermal aging at the operating temperature of light water reactors (LWRs). The change in the SQUID output strongly depended on aging temperatures and ferrite contents of unaged duplex stainless steel specimens. (author)

[en] Nondestructive evaluation (NDE) of iron-based material (A533B) has been investigated on magnetic property change caused by static tensile stresses up to 640 MPa for the yield of 540 MPa of this material. We obtained relative magnetic parameter changes at each spatial point by using a GaAs Hall element for magnetic leakage flux observation, and by measuring magnetic Barkhausen noises with a conventional pick-up coil to determine absolute values of residual strains. The total degree of degradation over a sample was determined with these two experiments. The innovation of the new diagnosis tool for the material fatigue was attained by magnetic noise analysis insensitively against any parameter changes composed of the geometrical roughness of the sample surface and the coupling manner of the internal flux with the installed pick-up coil for magnetic noise measurements. The residual stresses and the magnetic anisotropies in the Lueders band caused by 0.1% deformation were found, which are tilted at an angles about 35 degrees and distributed between 25-45 degrees to the sample direction with local residual stresses up to 40 kg/mm². These were attained by a high sensitivity detection of leakage flux density of 100 nT with a short lift-off distance as small as 200 μm. (author)

No abstract available

[en] Post-installed adhesive anchor bolts are commonly used on all types projects, from standard buildings to bridges and nuclear power plants. They are exposed to varying and diverse environmental conditions which are significant successfully to make connections to concrete structures for many years. With the failure of adhesive anchors in the Boston I-90 Tunnel Project, the use of these types of anchors has been called into question in America. On the other hand, also in Japan, a section of the SASAGO tunnel’s suspended concrete ceiling with adhesive anchor bolts became detached from the tunnel roof and fell onto the vehicles, 2012. In order to maintain the safety and reliability of concrete structures such as buildings or bridges on higher level over a long period time, we developed a new non-destructive inspection system of adhesive anchor bolts based on hammering tests using AE (acoustic emission) sensor. By adjusting the amount of resin of adhesive anchors, the model bolts with poor construction quality were made on concrete blocks and finite element analysis was carried out to evaluate performance of this inspection system. (author)

No abstract available

[en] An experiment conducted at ∼400 degrees C on simple model austenitic alloys (Fe-15Cr-16Ni and Fe-15Cr-16Ni-0.25Ti, both with and without 500 appm boron) irradiated in the FFTF fast reactor at seven different dpa rates clearly shows that lowering of the atomic displacement rate leads to a pronounced reduction in the transient regime of void swelling. While the steady state swelling rate (∼1%/dpa) of these alloys is unaffected by changes in the dpa rate, the transient regime of swelling can vary from <1 to ∼60 dpa when the dpa rate varies over more than two orders of magnitude. This range of dpa rates covers the full span of fusion, PWR and fast reactor rates. The origin of the flux sensitivity of swelling arises first in the evolution of the Frank dislocation loop population, its unfaulting, and the subsequent evolution of the dislocation network. There also appears to be some flux sensitivity to the void nucleation process. Most interestingly, the addition of titanium suppresses the void nucleation process somewhat, but does not alter the duration of the transient regime of swelling or its sensitivity to dpa rate. Side-by-side irradiation of boron-modified model alloys in this same experiment shows that higher helium generation rates homogenize the swelling somewhat, but do not significantly change its magnitude or flux sensitivity. The results of this study support the prediction that austenitic alloys irradiated at PWR-relevant displacement rates will most likely swell more than when irradiated at higher rates characteristic of fast reactors. Thus, the use of swelling data accumulated in fast reactors may possibly lead to an under-prediction of swelling in lower-flux PWRs and fusion devices.

[en] Solution annealed (SA) 304 and cold-worked (CW) 316 austenitic stainless steels were irradiated with protons in order to study the potential effects of helium, irradiation dose, and irradiation temperature on microstructural evolution, especially void swelling, with relevance to the behavior of austenitic core internals in Pressurized Water Reactors (PWRs). These steels were irradiated at 300 C with 1 MeV protons at doses up to 10 dpa. Both steels were irradiated either with or without 15 appm helium pre-implantation. Irradiation was also conducted at 340 C, but only with 15 appm helium pre-implantation. Transmission electron microscopy (TEM) revealed that small, heterogeneously distributed voids were observed in both alloys at 300 C, but only after helium pre-implantation. At 340 C, however, both SA 304 and CW 316 steels exhibited homogeneous void formation, suggesting a significant role of both helium and irradiation temperature in void nucleation. Compared with CW 316 voids developed sooner in the SWA 304 alloy at 300 and 340 C, consistent with the behavior observed at higher temperature (>370 C) in the EBR-II fast reactor, but the development of the Frank loop microstructure with increasing exposure with similar in both alloys. Helium pre-implantation had a measurable effect on the details of Frank loop formation

[en] Post-installed adhesive anchor bolts are commonly used on all types projects, ranging from standard buildings to bridges and nuclear power plants. They are faster to install, generally considered to be stronger, more flexible, easier to use and more reliable in majority of applications at ambient temperatures. They are exposed to varying and diverse environmental conditions which are significant successfully to make connections to concrete structures for many years. With the failure of adhesive anchors in the Boston I-90 Tunnel Project, the use of these types of anchors has been called into question in America. On the other hand, also in Japan, a section of the Sasago tunnel's suspended concrete ceiling with adhesive anchor bolts became detached from the tunnel roof and fell onto the vehicles, 2012. In order to maintain the safety and reliability of concrete structures such as nuclear plants on higher level over a long period time, we developed a new non-destructive inspection system of adhesive anchor bolts based on hammering tests using AE (acoustic emission) sensor. By adjusting the amount of resin of adhesive anchors, the mockup anchors with poor construction quality was made on concrete blocks and mockup experiment was carried out to evaluate performance of this inspection system. As a result of the mockup experiment, peak frequency of signal obtained from AE sensor shifted to lower frequency as the amount of resin decreased. In this mockup experiment, it was confirmed that our developed inspection system based on hammering tests using AE sensor had a large potential to evaluate adhesive anchor bolts. (author)

[en] Digital hammering inspection system with AE (Acoustic Emission) sensor has been developed and the effects of state, stiffness, etc. on the natural frequency of metal and concrete objects to be inspected were evaluated in terms of improper installations and age-related degradations. The system has been widely applied to social infrastructural diagnosis including expressways (West Nippon Expressway Company Limited, NEXCO-WEST), nuclear power plants (ex. Chubu Electric Power Co., Inc.), reprocessing plant of spent nuclear fuel (Japan Nuclear Fuel Limited) and a successful on-site trial of a new technology of i-Construction led by MLIT (the Ministry of Land, Infrastructure, Transport and Tourism). (author)

[en] Post-installed adhesive anchor bolts are commonly used on all types projects, from standard buildings to bridges and nuclear power plants. They are exposed to varying and diverse environmental conditions which are significant successfully to make connections to concrete structures for many years. In order to maintain the safety and reliability of concrete structures such as buildings or bridges on higher level over a long period time, we developed a new non-destructive inspection system of adhesive anchor bolts based on hammering tests using AE (acoustic emission) sensor. It was confirmed that our developed inspection system based on hammering tests using AE sensor had a large potential to evaluate adhesive anchor bolts. (author)