Preliminary thermal-hydraulic sub-channel analysis of 61 wire-wrapped bundle cooled by lead bismuth eutectic

Lead bismuth eutectic (LBE) is one of the most promising materials for coolant and spallation target for Accelerator Driven Systems (ADS). The thermal-hydraulic features in fuel assembly are one of the most important issues for development of this system. Aiming to get a deeper understanding on heat transfer behavior of wire-wrapped bundle cooled by LBE and to support the design of ADS systems, a fuel bundle simulator with 61 electrical rods spaced by helical wire was developed in KYLIN-II facility. In this paper, the preliminary heat transfer experiments with 70 kW under forced and natural circulation regimes were performed. The thermal-hydraulic behaviors including thermal entrance characteristics, heat transfer coefficients, and temperature distribution at the cross section were investigated under both regimes. The experiments depict reasonable results, and the Nu based on center sub-channel shows an agreement with empirical correlations. Besides, a special sub-channel code named SACOS-PB was employed to support the sub-channel analysis; and similar results to each other were obtained. It can be concluded that the SACOS-PB is a reliable tool for LBE system sub-channel analysis. Based on the present work the comprehensive thermal-hydraulic analysis with a detailed test matrix in terms of different flow rates and heating powers will be conducted in near future.