Investigation of the PWR Subchannel Void Distribution Benchmark (OECD/NRC PSBT Benchmark) Using ANSYS CFX

Abstract

The presented CFD investigations using ANSYS CFX 13.0 are focused on the “Phase I – Void Distribution Benchmark, Exercise 1 – Steady-state Single Subchannel Benchmark” of the OECD/NRC PSBT benchmark. In this particular subsection of the entire benchmark flow through a test section representing a central subchannel of a PWR fuel assembly under nucleate subcooled boiling conditions is investigated. The investigations using ANSYS CFX had been carried out for 10 different test conditions (with respect to pressure, inlet fluid temperature, power and mass flow rate) from the PSBT test matrix. Emphasis had been given to a CFD best practice guidelines oriented investigation of the subcooled nucleate boiling flow through the subchannel configuration of the test section. By comparing CFD results to the benchmark data reasonably good agreement could be observed. Depending on the applied CFD submodels the results differ from the measured data by ±8% with respect to cross-sectional averaged void fraction at the measurement plane, where the averaged void fraction varied between 0.038 and 0.62 for the test conditions under investigation.