Neutronics and thermal-hydraulics coupling analysis in accelerator-driven subcritical system. (April 2020)

• Record Type: Journal Article
• Authors: Ma, Yugao; Min, Jinkun; Li, Jin; Liu, Shichang; Liu, Minyun; Shang, Xiaotong; Yu, Ganglin; Huang, Shanfang; Yu, Hongxing; Wang, Kan
• Is Part Of: Progress in nuclear energy. Volume 122(2020)
• Publication Date: 2020-04
• Subjects: ADS -- Lead-bismuth eutectic -- Spallation target -- Multi-physics coupling -- Thermal-hydraulics feedback; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 333.7924
• DOI: 10.1016/j.pnucene.2019.103235
• Languages: English
• ISSNs: 0149-1970

Abstract

Abstract: Accelerator-driven subcritical system (ADS) is a new generation nuclear reactor with various highly coupled physical fields. A typical system is a liquid metal, lead-bismuth eutectic cooled subcritical reactor core coupled to a neutron spallation target. Therefore, ADS simulations require multi-physics coupling among the proton, neutronics, and thermal hydraulics. In this work, GEANT4, RMC, and FLUENT were used to simulate the multi-physics processes in MYRRHA. The GEANT4/RMC was used for the spallation process and the proton-neutron transport calculations, with the power distributions verified against the MCNP6 code with an average difference of about 1.85%. A hybrid RMC/FLUENT coupling scheme was used for the neutronics thermal-hydraulics calculations. The subcritical reactor was simplified using the porous media method for the FLUENT simulations to obtain the coolant temperature and density fields. A temperature-dependent thermal conductivity model used to calculate the temperature filed in typical fuel pellets gave consistent results with the FLUENT predictions within an absolute error of 3 K. The neutronics and thermal-hydraulics coupling took the temperature and the lead-bismuth eutectic density feedback into consideration. Simulations show that thermal-hydraulics feedback has a fairly small effect on the power distribution in the ADS reactor. In this case, the radial power difference between the coupling and coupling-free is within 5%. In addition, the mechanisms of neutronics/thermal-hydraulics are compared for lead-bismuth eutectic cooled reactors and water-cooled reactors. The feedback is much more significant in water-cooled reactors than in the Pb-Bi cooled reactor since the water moderation, and the water density is more sensitive to the temperature.