Science and Technology

PWR Reactor Vessel Multi-Physics CFD Model

Jin Yan*1, Yiban Xu1, Andrew Petrarca1, Zeses Karoutas1, Emre Tatli1, Emilio Baglietto2, Jess Gehin3

1Westinghouse Electric Company LLC

2Massachusetts Institute of Technology

3Oak Ridge National Lab

*Correspondence to:

A complete 3D SolidWorks CAD model of Watts Bar Unit 1 was constructed based on drawings. A single fuel assembly CAD model including all geometrical details was created based on the Westinghouse V5H 17x17 fuel design. The fuel assembly was then brought into the 3D reactor pressure vessel CAD model to form the entire reactor. From the 3D CAD model, computational meshes were generated for the reactor internals and the fuel assemblies. The meshes were assembled into a single mesh connected by interfaces on the Westinghouse large memory machine. Two CFD models were constructed based on different approaches to modeling the grid spacers. WBM1 uses porous media to simulate the grid spacer, while the grid spacer geometry is explicitly represented in WBM2. The CFD models were setup with the operating conditions of a typical PWR and a typical axial power profile. WBM1 was executed on the Westinghouse computer due to its relatively small size. WBM2 was executed on the ORNL super computer, Jaguar. Both models were post-processed on the Westinghouse large memory machine.

CAD, CFD Model, Pressure in Vessel

It is technically challenging to accurately simulate flow in the reactor vessel. The difficulty is a result of all aspects: complex physics, complicated geometry, difficult meshing, etc. Nevertheless, CFD results can provide many insights of the phenomena which cannot be easily obtained using other approaches. The current model development has the following benefits:

  1. Local thermal and/or hydraulic conditions such as temperature and two phase flow can be used to address challenge problems: CRUD, PCI, DNB, Cladding integrity during LOCA, Cladding integrity during Steam line break, AOA (Axial Offset Anomaly, Boron hide out in crud).
  2. The normal design concerns can also be addressed: Fuel centerline temperature, Cladding hot spot, Gray rod centerline temperature, Thermal mixing at hot leg
  3. Provide thermal boundary conditions for micro-scale models. The proposed process is the following:
CAD, CFD Model, Pressure in Vessel