Thermal-hydraulic constitutive equations implemented in the system analysis code AMAGI for nuclear power reactor

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Original languageEnglish
Article number103962
Journal / PublicationProgress in Nuclear Energy
Online published29 Sept 2021
Publication statusPublished - Nov 2021


Safety analyses of nuclear power plants heavily rely on system analysis codes. Massive and continuous works have been conducted to developing robust codes, such as TRACE, TRAC, RELAP5, NEPTUNE, ATHLET, SPACE, COSINE, etc. Recently, the Nuclear Regulatory Agency in Japan has developed the AMAGI code based on the constitutive equations adopted in the USNRC TRACE code. The AMAGI code with the default TRACE models demonstrated similar predictive performance to the TRACE code. The AMAGI code also implemented several state-of-the-art constitutive equations as optional models to further enhance the predictive code capability. The thermal-hydraulic parameters considered in the optional models were: distribution parameter for subcooled and bulk boiling flows in a rod bundle, drift velocity for two-phase flows in a pipe and a rod bundle, void fraction covariance and relative velocity covariance for two-phase flows in a pipe and a rod bundle, entrainment rate of liquid droplets, liquid droplet diameter, subcooled boiling interfacial heat transfer, wall friction coefficients in annular flow regime, onset of significant voiding in subcooled boiling flow, wall heat transfer coefficient in subcooled boiling flow, boiling transition at low-quality condition, minimum film boiling temperature, and rewetting. This paper reviewed the optional constitutive equations and provided recommendations for further improvement. The discussion was extended to the consistent momentum equation formulation for the interfacial drag force, including covariance and the covariance effect on the drift velocity. This paper also introduced the ongoing verification and validation effort of the AMAGI code. The AMAGI code demonstrated predictions similar to the TRACE code.

Research Area(s)

  • Accident analysis, AMAGI, Safety analysis, Thermal hydraulics, TRACE