Preliminary study of low flow-rate evaluation method by transport time-delay analysis of temperature fluctuation in a sodium circulation loop

Kanda, Hironori; Onojima, Takamitsu; Suzuki, Masashi; Imamura, Hiroaki; Tanaka, Masaaki  ; Murakami, Satoshi*

The flow rate of the primary coolant system in natural circulation decay heat removal operation is reduced much lower than that in rated operation in Next generation sodium-cooled fast reactor. The electromagnetic flow meters have uncertainty on the indicated value at low flow rates conditions. Ensuring the measurement accuracy of electromagnetic flow meter is presumed to contribute the promotion of understanding of thermal hydraulics phenomena such as natural circulation in the fast reactor. In this paper, low flow rate evaluation method has been examined preliminarily by transport time-delay analysis of temperature fluctuation in sodium circulation loop. Measured data and evaluation results from temperature fluctuations which have been acquired in sodium-loop in AtheNa, indicate that this evaluation method can be applied to estimate flow rate in natural circulation decay heat removal operation.