Session: 07-13: SMR and Advanced Reactors - II

Paper Number: 136210

136210 - Multi-Phase Large Leakage Sodium-Water Reaction Thermal-Hydraulics Analysis in a Sodium-Cooled Fast Reactor 

Abstract: 

The sodium-cooled fast reactor (SFR) is a promising generation-IV design with the nuclear system using liquid sodium as a coolant, high uranium utilization, and a closed fuel cycle. When the double-end-guillotine (DEG) heater tube broke in the steam generator of SFR, a high-pressure and high-temperature hydrogen bubble grew, with a large leakage sodium-water reaction (SWR) occurring. The reaction not only caused the pressure and temperature to increase promptly but also diffused the multi-phase flow (sodium-hydrogen-sodium-sodium hydroxide) into the steam generator and the secondary loop, which threatened the integrity of the secondary loop and the safety of the key equipment, such as the steam generator, surge tank, and protection system.

In this study, a Multi-phase hydrodynamic Analysis code for laRge Leak sodIum-water reactioN (MARLIN) calculating one-dimensional compressible multicomponent multi-phase flow with sodium–water chemical reaction was developed. The continuity equation, momentum equation and energy equation were applied to derive the MARLIN model. The hyperbolic-type partial differential equation was solved by the method of characteristic. FORTRAN language was used to develop the code. Critical equipment in the secondary loop model includes the steam generator, surge tank, pump, intermediate heat exchangers, rupture disks, and primary and secondary discharge accident tanks. The ACENA code results calculating the sodium-air flow were used to verify the multi-phase code. A good agreement was reached between the ACENA code and the MARLIN code.

Based on the structure of the sodium-water reaction experiment, the developed large leakage SWR accident model was applied to calculate the sing-phase sodium flow and multi-phase sodium-hydrogen-sodium hydroxide flow. The tendency of calculated flow pressure and velocity is consistent with the experiment date. The comparison of the results between the calculated model and experiment data was performed to indicate the higher accuracy of multi-phase flow dynamic analysis. It can be found that the multi-phase sodium-hydrogen-sodium hydroxide flow result was more reasonable and accurate in simulating and analyzing the actual large leakage SWR dynamics in the SFR.

Then, the large leakage SWR accident model was performed to investigate the secondary loop multi-phase flow dynamic characteristic. In this case, the protection system action, including the rupture disks, feedwater isolation valve action, release pipe flow rate, and monitoring and alarm signals, was simulated. The integrity of the secondary loop can be guaranteed.

The MARLIN code and the accident process analysis in this study are valuable for steam generator design and protection from the large leakage sodium-water reaction accident in the SFR.

Presenting Author: Xi Bai Xi’an Jiaotong University

Presenting Author Biography: My name is Xi Bai, a Ph. D candidate student at Xi’an Jiaotong University, and my major is Nuclear Science and Technology. My research interest is thermal-hydraulics analysis of steam generator heater pipe break accident, the Brayton Cycle for liquid mental reactors, and automatic control algorithms. My current project is focused on large leakage sodium-water reaction accident analysis.

Authors:

Xi Bai Xi’an Jiaotong University
Peiwei Sun Xi’an Jiaotong University
Xinyu Wei Xi’an Jiaotong University