Evaluation of Primary Water Stress Corrosion Cracking Resistance of Three Heats of Alloy 600 in 400 °C Hydrogenated Steam Condition

For Alloy 600, primary water stress corrosion cracking (PWSCC) is one of the key material degradation mechanisms in pressurized water reactors (PWRs). To identify the governing factors of PWSCC resistance, a systematic investigation into the role of each factor was performed. A PWSCC initiation test was performed for 3 heats of Alloy 600 in the 400 °C hydrogenated steam condition. Based on the test results, the effects of known factors like chemical composition, mechanical strength, grain boundary carbide coverage, grain boundary character, and surface cold work on PWSCC resistance were discussed. In addition, surface oxide morphology and penetrative oxide depth was compared. From this study, grain boundary character was considered to be the most dominant factor affecting the PWSCC resistance

The Current Status and Future Prospects of KAGRA, the Large-Scale Cryogenic Gravitational Wave Telescope Built in the Kamioka Underground

International audienceKAGRA is a gravitational-wave (GW) detector constructed in Japan with two unique key features: It was constructed underground, and the test-mass mirrors are cooled to cryogenic temperatures. These features are not included in other kilometer-scale detectors but will be adopted in future detectors such as the Einstein Telescope. KAGRA performed its first joint observation run with GEO600 in 2020. In this observation, the sensitivity of KAGRA to GWs was inferior to that of other kilometer-scale detectors such as LIGO and Virgo. However, further upgrades to the detector are ongoing to reach the sensitivity for detecting GWs in the next observation run, which is scheduled for 2022. In this article, the current situation, sensitivity, and future perspectives are reviewed.</jats:p