Neutronic and fuel cycle performance of VVER-1000 for dual cooled annular fuel with coated burnable poison

The feasibility of the dual cooled annular fuel rod with coated burnable absorber in the hexagonal assembly of the VVER-1000 reactor was studied. The models consist of a 4.5% enriched dual cooled UO2 fuel rod with a coating of Gd2O3, Er2O3, PaO2, AmO2, and ZrB2 as the burnable absorber. Designed models along with the reference designs were simulated in lattice physics code Dragon and Monte Carlo code OpenMC. Burnup analysis was conducted for 1620 EFPD. The multiplication factor, as well as reactivity, was determined for fuel burnup. Improvement in the multiplication factor and reactivity is observed for dual cooled annular fuel with coated burnable poison. Designed models also showed a significant increase in thermal fission reaction rate compared to the reference design. Linear reactivity model (LRM) was used to calculate cycle burnup, discharge burnup, and cycle length for three and four batch refueling schemes. No degradation is observed in fuel cycle performance using dual cooled annular fuel with coated burnable absorber except for the model of gadolinium. The other absorbers showed better results than gadolinium in both neutronic and fuel cycle performance. PaO2 used model showed the most promising result among them. The value of k-infinity was found to be 1.27089 at BOL and the cycle burnup was around 15 MWD/kg. Also, no cycle length penalty was observed for PaO2. Burnup-dependent atomic concentration was studied. A lower concentration of fission product poison was also noticed in designed models. The analysis of relative pin power distribution and energy-dependent neutron flux is also included in this study.