Experimental investigation on repeatability of CHF in rod bundle with non-uniform axial heat flux distribution

Abstract

Critical heat flux (CHF) is important to thermal-hydraulics design and safety analysis. In the purpose to validate the CHF data acquired from LS-THTF of NPIC, experimental investigation on repeatability of the CHF data is carried out with full length non-uniform axial heat flux distribution rod bundle. The repeatability of the CHF data from LS-THTF itself is examined by comparing the data from the same run but different time and data from different runs. The rod bundle powers of CHF data acquired under well controlled parameters are directly compared with reference measured data from HTRF of Columbia University. The rod bundle power ratio of CHF data is employed to describe the repeatability of CHF data from LS-THTF to HTRF, and the variations of power ratio with inlet and outlet parameters show a reasonable trend. The point to point differences of CHF power between the two facilities of every single point are found to be within 5%. The result demonstrates good repeatability between data from LS-THTF and data from HTRF. LS-THTF is capable of acquiring reliable and repeatable CHF data to verifying thermal-hydraulics performance of PWR fuel assemblies.