Abstract
The heat removal capability of systems using natural circulation depends on natural circulation flow rate. Therefore, accurate prediction of natural circulation flow rate is important for safety design. The purpose of this study is to obtain the natural circulation data and develop the evaluation method of natural circulation flow rate under two phase conditions. Natural circulation experiments are conducted at atmospheric pressure, using air-water mixtures in both single channel and multi-channel. Major conclusions are as follows; (1) Experimental data for verifying the evaluation method of natural circulation flow rate can be obtained. (2) Void fraction model and two phase multiplier model are selected by comparing test results. Evaluation method of two phase natural circulation flow rate is developed. (3) In single channel and multi-channel, evaluations of natural circulation flow rate and pressure distribution along test loop are in good agreement.
