Study on parameter importance ranking of the OECD/NEA PKL4 test i2.2 with efficient moment-independent sensitivity analysis

The intermedium break loss of coolant accident (IBLOCA) benchmark study was carried out on the OECD/NEA PKL-4 facility test i2.2 to explore the influence of break size on the peak cladding temperature (PCT). Results of the blind calculations performed by different participants showed that the transient behaviors of the scenario can be well predicted, but further improvements were needed for some local phenomena. In this paper, the global sensitivity analysis was carried out to investigate the influences of 36 input parameters on the PCT and minimum core water level (MCWL) with an efficient moment-independent method, and the sensitivity measures as well as corresponding importance rankings were obtained. The obtained results can deepen the understandings of the key phenomena in the IBLOCA test, and provide guidance to the model optimization and code verification. In addition, the adopted sensitivity analysis method can be extended to other tests of the PKL facility.