Assessment of thermal-hydraulic codes against boron transport phenomenon at system level

The present paper deals with an application of the systematic procedure for code assessment and uncertainty quantification developed at the University of Pisa, to the Cathare2, RELAP5 and RELAP5-3D system codes, in order to evaluate their capabilities to reproduce the thermalhydraulics of an inadvertent boron dilution event in a Pressurized Water Reactor (PWR). The selected tests are E2.2 and F1.1 boron dilution experiments carried out at the PKL III facility. The quantitative analysis has been performed adopting a method developed at DIMNP, which allows to quantify the errors in code predictions related to the measured experimental signal. The Fast Fourier Transform (FFT) is used to obtain an integral representation, in the frequency domain, of the discrepancies between measured and calculated time histories. The results obtained by Cathare2 code are proprietary data and they are reported only in general terms