Numerical simulation on thermal-hydraulic characteristics in fuel assemblies of supercritical water cooled reactors using two-fluid model analysis code ACE-3D

Nakatsuka, Toru  ; Misawa, Takeharu; Yoshida, Hiroyuki  ; Takase, Kazuyuki

In order to assess the thermal hydraulics in fuel assemblies of the supercritical water cooled reactor (SCWR) core, JAEA has been enhancing the three-dimensional two-fluid model analysis code ACE-3D to predict thermal-hydraulic behavior of the SCWR. As a part of these assessments, the present paper describes numerical analysis results on thermal-hydraulic characteristics in the fuel assembly based on the design of the supercritical water cooled fast reactor (Super Fast Reactor) concept. The analytical geometry simulates a 19-rod assembly, which is one of the most simplified geometry of the SCWR fuel assembly and includes three kinds of different subchannel types: (1), adjacent to the channel box; (2), next to type (1); and (3), located inside types (1) and (2). The results show the influence of existence of the channel box and variation of the rod surface temperature profiles in the circumferential direction.