Failure Analysis on AFA 3G Gd Rod from Nuclear Power Plants

The coolant radioactivity increased during the reactor operation, and a Gd rod was suspicious to be failed. The post-irradiation examination in China Institute of Atomic Energy confirmed that both ends of the Gd rod were failed, and the hydrogen content analysis showed that the hydrogen content at the position of lower plug welding was 1720μg/g, while that was only 133μg/g at the position nearby the upper plug hole welding. That means the failure at lower plug welding was a secondary failure, and the upper failure was primary. The failure root cause of Gd rod was hole welding failure.