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

Paper Number: 135512

135512 - Numeral Research on Thermal-Hydraulic Characteristics of Pebble Bed in Wccb Blanket Under In-Box Loca 

Abstract: 

Blanket is the core component of a fusion reactor, its main functions are to produce tritium for self-sustaining, to bring fusion energy out for electricity generation, and to shield against neutron radiation. China has developed Helium Cooled Solid Breeder (HCSB)blanket, Water Cooled Ceramic Breeder (WCCB)blanket, Dual Functional Lithium Lead Test Blanket System (DFLL TBS) and other conceptual design programs. Water Cooled ceramic Breeder (WCCB)blanket, as a class of candidate breeding blanket programs for fusion reactors, has a series of advantages, such as high thermal conversion efficiency and compact structure, technological sustainability and a good prospect for application. 
However, Water Cooled Ceramic Breeder (WCCB)blanket adopts high-temperature and high-pressure coolant and a solid proliferating spherical bed with low thermal conductivity. There is a high possibility that some coolant pipes will break in the breeding zone, which is so-called In-box Loss of Coolant Accident (In-box LOCA). When the accident occurs, high pressure water will be sprayed into the low-pressure high-temperature spherical bed and flashing occurs, bringing about drastic changes in the pressure, temperature, and velocity fields in the blanket in a very short period, which involves a complex heat- and mass-transfer behavior and the formation of a complex multiphase flow and shockwave effect, and may lead to peak pressure exceeding the design limit, which in turn poses a threat to the integrity of the blanket structure, making it face serious safety problems under the In-box LOCA accident. Therefore, to improve the safety of the cladding and avoid the leakage of radioactive materials, it is necessary to carry out an in-depth study on the transient process of In-box LOCA accident.
At present, research on thermal-hydraulic analysis of Water Cooled Ceramic Breeder (WCCB)blanket under In-box LOCA mainly focuses on the system level and lacks research on the internal three-dimensional structure of the cladding. In this paper, the complex changes of WCCB cladding module under breach accident are simulated and analyzed by numerical simulation method using CFD software ANSYS FLUENT.
It mainly includes:   
1. The flashing mechanism model under high pressure (15.5MPa) is constructed, in which the changes of boiling point and latent heat of vaporization with pressure and temperature in the flashing process are defined; the physical properties of water, water vapor, and helium are processed by UDF self-defined programming to accurately simulate the propagation process of the pressure wave.
2. Research the two-phase flow characteristics and consequences of water-cooled Ceramic Breeder (WCCB)blanket In-box LOCA; analyze the effects of key parameters affecting the pressure propagation of the blanket system after In-box LOCA, such as the defect size, defect area, discharge pressure, and dome bed temperature, etc., and accurately characterize the flow characteristics and heat transfer properties of the coolant in the bed during the discharge process of the breach accident. It lays the theoretical foundation for the safe design and application of Water Cooled Ceramic Breeder blanket.

Presenting Author: Jie Cheng Harbin Engineering University

Presenting Author Biography: Jie Cheng
PhD, 2019, Xi'an Jiaotong University, Nuclear Engineering
BS, 2011, Xi'an Jiaotong University, Nuclear Engineering
Occupation:
Associate Professor, 2023-recent, Harbin Engineering University, College of Nuclear Science and Technology
Assistant Professor, 2019-2023, Harbin Engineering University, College of Nuclear Science and Technology
Visiting scholar, 2016-2018, University of Nevada, Las Vegas, Mechanical Engineering (Center for energy research)
Research field:
Reactor multi-scale and multi-physics coupling method;
Fusion reactor blanket design and physical/thermal/mechanical analysis;
Development of multi-objective optimization algorithm for nuclear power plant;
Conceptual Design of Advanced Reactor System.

Authors:

Hanlin Bai Harbin Engineering University
Jie Cheng Harbin Engineering University
Shuaiyu Han Harbin Engineering University
Di Wu Harbin Engineering Uinversity
Jianjun Wang Harbin Engineering University