Session: 04-02: SMRs, Advanced Reactors and Fusion

Paper Number: 134289

134289 - Steam-Water Two-Phase Flow Testing Under Nominal Pressure and Temperature Conditions for Natural Circulation Performance of Chimney in Bwrx-300 Smr 

Abstract: 

The BWRX-300 is a water-cooled natural circulation small modular reactor developed by GE Hitachi Nuclear Energy in cooperation with Hitachi-GE Nuclear Energy. BWRX-300 is equipped with passive safety systems and leverages the design and licensing of USNRC-certified ESBWR (Economic Simplified Boiling Water Reactor). Like the ESBWR, the BWRX-300 uses a tall chimney above the core to provide natural circulation head to drive sufficient core flow and ensure fuel is operated within its thermal limits. Thus, calculated void fraction in the chimney is a key quantity for estimation of the natural circulation core flowrate in the BWRX-300. BWR transient analyses are performed with TRACG (Transient Reactor Analysis Code, GE version) which has been qualified for calculating thermal limits in BWRs including the natural circulation ESBWR. This extent of qualification includes the evaluation of core flow rate and evaluation of void fraction in chimney or upper plenum of BWRs. To support extending the TRACG qualification of void fraction evaluation to the large-diameter simplified chimney of BWRX-300 additional test data were obtained with steam-water two-phase flow test and the void fraction modeling and calculation in TRACG were validated. The test was conducted in Hitachi Utility Steam Test LEading facility (HUSTLE) using a chimney test section, which was down-scaled to around 0.5 m in diameter. Length-to-diameter ratio of the test chimney was more than in the actual design of the BWRX-300 and porous plates were installed at the chimney inlet and outlet with the ratio of openings to the total cross-sectional area nearly the same as in the BWRX-300 design. The void fraction in the chimney cross section were measured by differential pressure gauges and the Double-plane Wire-mesh Sensor (DWS) for nominal BWR operating conditions of 7 MPa and 290 °C and flow conditions scaled from conditions of BWR-300 chimney at a range of reactor power levels. The validity of the DWS data was confirmed by comparing the cross-sectional average void fractions with data from a differential pressure gauge. The measured results in the spatial distributions of the void fraction and velocities of the gas-liquid interface indicate the flow pattern in the chimney. Based on time-domain CT images of void fraction from the DWS data, the dominant flow regime observed in the chimney was identified using comparison with the existing flow map for large-diameter pipes. Furthermore, the average void fraction in the chimney was estimated by the TRACG model and the model performance was confirmed. Consequently, the qualification of the void fraction estimation of the TRACG model was extended to the large-diameter chimney of BWRX-300.

Presenting Author: Hajime Furuichi Hitachi-GE Nuclear Energy, Ltd.

Presenting Author Biography: Hajime Furuichi was born in Aichi, Japan, in 1988. He received the B.S. and M.S. degree in mechanical engineering from Shizuoka University, Shizuoka, Japan, in 2012 and 2014, where he focused on fiber-optic measurement in multiphase flows. Since 2014, he has been with Hitachi, Ltd., Ibaraki, Japan. His current research interests include estimation technique for critical power of BWR fuels, measurement, and gas-liquid two-phase flows.

Authors:

Hajime Furuichi Hitachi-GE Nuclear Energy, Ltd.
Antonin Povolny Hitachi-GE Nuclear Energy, Ltd.
Kenichi Katono Hitachi-GE Nuclear Energy, Ltd.
Kenichi Yasuda Hitachi-GE Nuclear Energy, Ltd.
Kazuaki Kito Hitachi-GE Nuclear Energy, Ltd.
Charles Heck Global Nuclear Fuel – Americas, LLC