Analisis Neutronik Penambahan Thorium pada SUNRISE-LFR Berpendingin Timbal-Bismut Eutektik dengan Bahan Bakar Uranium-Plutonium

Abstract

SUNRISE-LFR (Small Uranium Nitride Reactor for Innovative Sustainable Energy–Lead-cooled Fast Reactor) is a Generation IV fast reactor design that uses lead-bismuth eutectic (LBE) coolant and uranium nitride–plutonium nitride (UN PuN) fuel. The use of thorium in fast reactor fuel has the potential to increase the production of the fissile isotope 233U through the breeding process while maintaining the reactor’s neutronic characteristics. This study aims to analyze the effect of adding thorium on neutronic parameters and the effectiveness of 233U production in the SUNRISE-LFR design. Simulations were performed using OpenMC version 0.13.3 based on the Monte Carlo method with ENDF/B-VIII.1 nuclear data library. The calculations employed 30,000 particles per batch, 200 total batches, and 30 inactive batches to ensure statistical convergence. The study began with reactor model benchmarking, followed by optimization of the UN–PuN fuel composition, variations in the thorium fraction in Reactor Core Rings 1, 2, and 3, and analysis of burn-up over a three-year period. The parameters analyzed include the effective multiplication factor (𝑘𝑒𝑓𝑓), Power Peaking Factor (PPF), Breeding Ratio (BR), and Fissile Inventory Ratio (FIR). The optimization results show that a fuel composition of 90% UN and 10% PuN yields a 𝑘𝑒𝑓𝑓 value of 1.01391 ± 0.00026, which is closest to critical conditions. The addition of Thorium causes a decrease in the 𝑘𝑒𝑓𝑓 and PPF values, while increasing the BR and FIR values. The optimal configuration was obtained in 2 Ring with a ThN content of 15%, yielding a 𝑘𝑒𝑓𝑓 value of 1.00200 ± 0.00027, a PPF of 1.276, a BR of 0.23111, and an FIR of 1.06835. The research results indicate that the addition of thorium to the SUNRISE-LFR is capable of enhancing the 233U breeding capability while maintaining good neutronic characteristics.