Recently, operation life of nuclear power plants is being extended, therefore, the maintaining the reactor vessel integrity is one of the most important matters in Japan. In these years, some leakages from penetration of alloy 600 CRDM and BMI were reported. B MI penetration is becoming one of the most critical issues in PWR components.In this paper, we introduce four new inspection techn iques including Visual testing (VT), Eddy current Testing (ECT), Adaptive Focusing UT (AdF-UT) and SAFT-UT for the BMI ...
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Development of Inspecting Techniques for BMI J-Welds of PWR Nuclear Power Plants

Abstract In the nuclear power plants, the reservation of safety and before-it-happens prevention of a trouble are important themes. Moreover, in connection with the life extension of a plant, life-expectancy diagnosis has also been an important subject. Although it is technology required in order that a non-destructive test may secure the safety of a power generation plant, Ultrasonic Testing (UT) is applied. However, generally the welding of stainl ess steel piping used widely in the PWR type nuclear powe...
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Ultrasonic Testing Technique for Stainless Steel Pipe

In Japan, the preventive maintenance task of the 600 series nickel basis alloy weld of the reactor vessel (RV) and the steam generator (S/G) safe end weld are pushed forward sequentially, and a defect sizing using the ultrasonic testing (UT) from the inside of the safe end is carried out when the defect was dete cted by surface inspection prior to the work. Some defects are recognized on the S/G safe end and the R/V safe end in Japan, and these defects have occurred in the axial direction of the safe end w...
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Development of Advanced Defect Sizing Technique Using Ultrasonic Testing for Nozzle Welding

In the nuclear power plant, ultrasonic testing is performed as an in-service inspection of the reactor vessel (RV-ISI) according to JSME code. MHI is using the advanced UT machine (A-UT machine) system to RV-ISI under the high radiatio n condition. RV-ISI is one of the critical path in ISI schedule, so it is strongly required to reduce the inspection t ime of RV-ISI. In this report, the counter measure to reduce RV-ISI period by using the phased array UT is described....
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Application of Phased Array UT to RV Safe End Welds Inspection

Recently, preventive maintenance tasks for welding of safe-end nozzles of reactor vessels and steam generators of PWRs in Japan had been carried out sequentially. Before the maintenance tasks, inspection services were carried out and several crack indications were found by eddy current testing (ECT). These indications were found in the welding which made b y 600 series nickel base alloy and evaluated as stress corrosion cracks which were oriented to the axial direction of the nozzle. Then investigations to...
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Development of the advanced phased array UT technique for accurate sizing of cracks in the nozzlewelding

The probe to be applied for the inner surface of the CRDM tubing having a narrow portion of the reactor vessel, however existing probe is not applicable to the minimum gap 1.5 mm of the CRDM tubing. It is necessary to study further thinning of the probe while maintaining sufficient detectability and flaw direction discrimination. Therefore, a new coil system using pancake coils was developed. As a result of a verification test, it was confirmed that an EDM flaw of 0.2 mm in length, 0.2 mm in width and 0.2 m...
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 Verification of new thin ECT probe for reactor vessel head nozzle