For evaluating the soundness of steel rods and pipes, which are installed in nuclear power plants, we have developed a new inspection system using an AE (acoustic emission) sensor. This report described the results of studies for the detection of defects in the steel pipe and steel rod using a new inspection system. ...
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Development of a new inspection system for steel rod and pipe using AE sensor 2 (1) Experimental approach

Time-of-flight ultrasonic measurements were conducted on a thick hexagonal block of 304 type austenitic stainless steel, which was used as a reflector in EBR-II and was irradiated to 23 ~ 33 dpa at 37 0 ~ 410 ?C. The results of ultrasonic-implied void swelling and carbide-induced densification were compared with those obtained by immersion density measurements and transmission electron microscope o bservations. The three types of measurements were found to agree rather well with each other, and the variati...
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Development of a non-destructive inspection technique for detecting irradiation-induced microstructural changes of austenitic stainless steels by use of an EBR-II reflector

Fiber reinforced plastic (FRP) is used in a wide range of applications due to its light weight, high strength, excellent corrosion resistance and flexible processability. Although nuclear power plants may have a chance to use FRP as structural and equipment materials in the future, its radiation effect is not well known so far. Thus, we tried to evaluate its radiation degradation non-destructively using "AE (Acoustic Emission) digital hammering inspection". Two types of FRP test specimens of glass fiber and...
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Development of nondestructive inspection system for soundness diagnosis of FRP

On-site trial of a new technology of i-Construction was successfully carried out for the quality control of concrete construction through hammering inspection using AE sensor. In addition, some mockup tests showed that the inspection has a potential to identify several defects and compressive strength of concrete....
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On-site trial of a new technology of i-Construction: Quality control of concrete construction through hammering inspection using AE sensor

Quantitative inspection method of corrosion using ultrasonic testing was developed in order to maintain reliability of anchor bolts. Quantity of corrosion can be measured precisely even if the anchor bolt was installed on concrete ba se. In addition to quantity of corrosion, the distance from bolt head and the length of corroded region were estimat ed by improved method. Mock-up tests were conducted for the purpose of evaluating detection capability of the method....
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Development of Quantitative Inspection Method of Corrosion on Anchor BoltsUsing Ultrasonic Testing

Ultrasonic testing was conducted on two long (218-245 mm), Type 304 stainless steel blocks with a hexagonal cross-section (50 mm face-to-face thickness) that were removed from the reflector region of the decommissioned EBR-II reactor. Ultrasonic testing is one of the widely used non-destructive testing techniques for material characterization. Ultrasonic waves, currently used as a non-destructive technique to detect cracks, change as a result of interacting with microstructural components and can be em...
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Development of non-destructive inspection technique for microstructures under irradiation using austenitic stainless steel blocks

Chemical anchor is a glue-type anchor and it has been used to fix components to concrete structures in nuclear power plant. Decrease in adhesive power of glue is supposed to occur due to a construction failure or a long term use under various environments in actual plant. We have begun some internal researches and selected Acoustic Emission method (AE) as a non- destructive inspection tool among some methods. The AE method was selected by a comparison of some methods, and then the methodology was brushed...
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Development of inspection method for chemical anchor

Insulation degradation of cable insulation causes fire due to electric leakage. Cable insulating materials laid in nuclear power plants deteriorate over time, heat and influence of radiation. Here we investigated the degradation tendency of insulating materials by radiation irradiation by hammering inspection using AE sensor. As a result, for any cable insulation material, curing of insulating material with irradiation could be detected as a change in natural frequency. From here, the applicability of AE ha...
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Development of nondestructive inspection system for soundness diagnosis of cable insulating material

We reported previously the deterioration tendency of cable insulation materials used in nuclear power plants due to irradiation and the applicability of AE (Acoustic Emission) digital hammering inspection to detect the deterioration nondestructively by comparing the natural frequencies before and after the irradiation. In this study, we selected two kinds of triple core cables which are often utilized in nuclear power plants. The natural peak frequency increased due to the increase of irradiation dose, and ...
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Development of nondestructive inspection system for soundness diagnosis of cable insulating material (2)

We have researched radiation-induced deterioration behaviors of cable insulation materials used in nuclear power plants and a nondestructive inspection method to detect the behaviors in our past reports. The deterioration was generated by electron beam irradiation simulating gamma-ray irradiation in the field. As a result, we found it possible to detect the deterioration by comparing the natural frequencies of the cables before and after the irradiation through our original digital hammering inspection tech...
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Development of nondestructive inspection system for soundness diagnosis of cable insulating material (3)