223.1 FA2D Prediction Capability for NPP Krsko Fuel Assembly Calculation Dubravko Pevec, Davor Grgić, Radomir Ječmenica Faculty of Electrical Engineering and Computing Univeristy of Zagreb Unska 3, HR-10000 Zagreb, Croatia dubravko.pevec@fer.hr, davor.grgic@fer.hr , radomir.jecmenica@fer.hr ABSTRACT FA2D is 2D transport collision probability code developed at Faculty of Electrical Engineering and Computing, University Zagreb. It is used for calculation of cross section data at fuel assembly level. Usual application of obtained cross section data, including pin power reconstruction data, is within NRC’s PARCS code for 3D core calculation. This paper presents results of calculations performed for NPP Krsko 16x16 standard fuel and NGF fuel with different number of IFBA rods and for different Gd 2 O 3 content. Two codes are used in calculation: FA2D and SCALE5 TRITON calculation sequence (based on discrete ordinates code NEWT). The results obtained with FA2D spectral code for reflected heterogeneous 2D fuel assembly geometry are presented for burn-up dependency of infinite multiplication factor, 2D pin power distributions, and for local peaking factor. 1 INTRODUCTION The computer code FA2D is used for generation of cross sections and related data of pin cells and fuel assemblies at Faculty of Electrical Engineering and Computing (FEEC), University of Zagreb. The code is developed at FEEC and it solves transport equation using the collision probability method. The verification of the code has been performed by benchmark calculations at pin cell and fuel assembly level, as well as fuel management calculations for the NPP Krsko and IRIS reactors. The 16x16 next generation fuel (NGF) and 16x16 standard fuel, containing IFBA rods and gadolinium rods as burnable absorbers, will be used for the subsequent cycles of the NPP Krsko. A generation of cross section for this type of the fuel we have performed by the calculational model of the FA2D code. We also modeled this type of the fuel by TRITON calculation sequence (based on the discrete ordinates code NEWT) of the SCALE5 computer code package. The calculational models are described in Section 2. The results obtained with two mentioned spectral codes are presented in Section 3. The conclusions of modeling NGF and standard fuel for NPP Krsko by FA2D and SCALE5 TRITON codes are given in Section 4. The Section 5 contains the references.