Fabricated of the SCC Reference Specimen for Increasing of In-Service Inspection Accuracy in Nuclear Power Plant

To achieve the safety assurance of nuclear power plants, in-service inspection have were enforced periodic for nondestructive test in weldment. Among them, ultrasonic evaluation is widely used measurement defects. Generally, non-destructive inspectors calibrated a UT machine using reference specimen artificial cracks such as EDM, mechanical notch. As reflected signal real crack was detected amplitude value 50% lower than cracks. Therefore, domestic little experience measuring actual generated plant field, SCC(Stress corrosion cracks, below SCC) and thermal fatigue cracking. Accordingly, order to improve accuracy during operation structures, it necessary lot inspecting cracks.In this study, non-penetration SCC educational NDT inspector fabricated by simulated environment system base metal STS 304 pipe. The size pipe 8 inch(80 sch., thickness 12.7mm). end flange simulating fixed structure. accelerate fabrication SCC, corrosive composed blending solution NaOH 1M Na2S9-H2O 0.1M inside potential hydrogen caustic 14. confirmed shape RT.