Session: 07-02: Experiments and Analyses - I

Paper Number: 133590

133590 - Design and Experimental Verification of Passive Residual Heat Removal System for a Alkali-Metal Heat Pipe Cooled Reactor 

Abstract: 

The high-temperature heat pipe cooling reactor has the advantages of compact structure, safety and reliability, which makes it have broad application prospects in Unmanned Underwater Vehicles(UUV). In this paper, a Passive Residual Heat Removal system(PRHR) is designed for a megawatt high-efficiency and compact new marine nuclear power plant proposed by the Chinese Academy of Engineering Physics. The PRHR efficiently utilizes the space of the adiabatic section of the heat pipe bundle, an emergency cooling chamber is established in this area, pre-filled with high-pressure coolant. The UUV shell, in direct contact with seawater, serves as a heat sink. Within the adiabatic section of the heat pipe bundle, the cooling water is heated and its temperature rises, causing a decrease in density. It flows towards the inner side of the UUV shell, releasing heat into the seawater through the UUV shell, thereby reducing its temperature. A density difference of coolant is established between the adiabatic section of the heat pipe bundle and the inner surface of the UUV shell, creating a closed-loop natural circulation. This passive process continuously cools the adiabatic section of the heat pipe bundle, exporting residual heat from the core. The CFD model of the PRHR was established and the geometric structure parameters of the system was optimized. The results indicate that the presence of hexagonal baffles at the periphery of the adiabatic section of the heat pipe bundle is superior to no baffles or circular baffles. The inlet and outlet widths of the hexagonal baffles exhibit negligible impact on the heat removal capability during the natural circulation process. Considering the influence of the power distribution within the core, where the temperatures of the heat pipes at the center are higher than those at the periphery, it is therefore recommended to set a 40mm opening at the center of the baffle inlet, while keeping the baffle outlet completely open. Furthermore, an analysis of the mass flow rates and coolant temperatures in various channels within the adiabatic section of the heat pipe bundle was conducted. Based on CFD study results, an experimental setup was designed to investigate the characteristics in heat removal capacity when subjected to the coolant with different temperatures and mass flow rates sweeping the heat pipe. Experimental results indicate that the heat removal capacity decreases with increasing coolant mass flow rate, exhibiting a logarithmic relationship; similarly, the heat removal capacity decreases linearly with the rise in coolant temperature. Based on the experimental findings, appropriate heat transfer correlation were selected, and a transient analysis of the nuclear power plant under a complete loss of heat sink accident was performed. The analysis results demonstrate that the designed passive residual heat removal system could meet the design requirements.

Presenting Author: Hexin Wu Xi'an Jiaotong University

Presenting Author Biography: PhD candidate, mainly engaged in high temperature alkali metal heat pipe research.

Authors:

Hexin Wu Xi'an Jiaotong University
Junli Gou Xi'an Jiaotong University
Ruifeng Wang Xi'an Jiaotong University
Leqi Yuan Xi'an Jiaotong University
Jianqiang Shan Xi'an Jiaotong University