Development of advanced neutronics/thermal-hydraulics coupling simulation system, 12; Uncertainty evaluation in developed measurement method for gas-liquid two-phase flow inside a fuel bundle using LDV

Ono, Ayako ; Okamoto, Kaoru*; Makino, Yasushi*; Hosokawa, Shigeo*; Yoshida, Hiroyuki  

JAEA has been developing an advanced neutronic/thermal-hydraulics coupling simulation system. In the coupling code, the detailed thermal-hydraulics codes based on an interface-capturing method (JUPITER or TPFIT) will be adopted to simulate thermal-hydraulics in a fuel bundle. The experimental data and findings relating to the two-phase flow in a fuel bundle are needed to validate the JUPITER/TPFIT codes. In the previous study, we proposed a new measurement method to measure the bubbly flow in a narrow channel, such as a subchannel, by combining laser-doppler velocimetry and photodiodes. In this study, we evaluate the uncertainty in the new measurement method arising from the signal processing and the method of the determination for bubble signals, using the newly developed LDV optical path simulator.