Evaluation of thermal striping for the plugging system in the secondary auxiliary cooling system in JOYO

Isozaki, Kazunori ; Ogawa, Toru; Kubo, Atsuhiko; Sugaya, Kazushi*; Aoki, Hiroshi; Ozawa, Kenji

Scrutiny based on the convenient evaluation to verify whether we have the place where thermal striping in the pipe confluence part was thought to be a primary factor for the heavy accident or not has been done in JOYO. As the result, the big temperature difference (Tin) of the simple inner pipe confluence part existed at the inner pipe confluence part of the plugging system in the secondary main and auxiliary cooling system. Therefore, detailed evaluation of thermal striping was needed. With the thermocouples of high response installed, the temperature fluctuation in outer surface of the pipe was measured on the secondary auxiliary plugging system for the reason why the temperature difference (Tin) was the biggest. And, the temperature fluctuation in inner surface of the pipe and stress occurring in the pipe plate thickness direction was evaluated by means of the temperature fluctuation measurement result and non-linear structure analysis system "FINAS". The above-mentioned evaluation results were as follows. (1)The maximum temperature fluctuation occurring in the pipe was always located from the center of inner pipe confluence to 10mm position of the down-stream side. (2)The maximum temperature fluctuation range was about 33C in outer surface of the pipe. And, controlling frequency of the temperature fluctuation was 0.04Hz and 0.09Hz. (3)Time delay was almost never contained in the temperature fluctuation elements between inner and outer surface of the pipe by dint of analysis results of the heat conduction by "FINAS". And, the big temperature distribution did not occur in the pipe plate thickness direction was confirmed that the big temperature distribution did not occur in the pipe plate thickness direction. (4)The temperature fluctuation in the pipe inner surface and the stress occurring in the pipe plate thickness direction was evaluated by use of result of the temperature fluctuation measurement and the heat conduction ...