Comparison of the Use of Fissile Material U-233 and Plutonium in Thorium Nitride (ThN) Fuel in Small Long-Life Modular PWR Cores at 300 MWth Power Level Boni Pahlanop Lapanporo (a,b*), Zaki Su^ud (a), Asril Pramutadi Andi Mustari (a)
(a) Department of Physics, Faculty of Mathematics
and Natural Sciences, Institut Teknologi Bandung
Jl. Ganesa 10, Bandung 40132, Indonesia
(b) Department of Physics, Faculty of Mathematics
and Natural Sciences, Universitas Tanjungpura, Jl. Prof.
Dr. H. Hadari Nawawi, Pontianak 78124, Indonesia
* boni8poro[at]physics.untan.ac.id
Abstract
In this study, neutronic calculations were conducted on thorium nitride (ThN)-based fuel with different fissile materials (U-233, reactor-grade plutonium (RG-Pu), weapon-grade plutonium (WG-Pu), and a mixture of RG-Pu and WG-Pu) in a small long-life modular PWR core with 300 MWth power. We calculated using the Standard Reactor Analysis Code (SRAC), employing the PIJ module for fuel cells and the CITATION module for the reactor core. The 3D XYZ reactor core model consisted of 89 fuel assemblies, each with 17x17 pins (264 fuel pins and 25 guide tubes). We composed the fuel pins of Th-232, fissile material, and Pa-231 as a burnable poison. We divided the core into three regions (F1, F2, F3) with increasing fissile material percentages from the center outward, differing by 1-2%. Results showed that U-233 and the mixture of RG-Pu and WG-Pu performed best, maintaining excess reactivity below 1.00% dk/k for 20 years. Power density distribution at a 65% fuel volume fraction was similar for all fissile materials, with plutonium being more uniform than U-233. All fissile materials had low and safe PPF values for PWRs. U-233 had the highest Doppler coefficient, RG-Pu the lowest, and WG-Pu increased at high volume fractions. The mixture of RG-Pu and WG-Pu had a moderate Doppler coefficient. Burnup levels were slightly lower for RG-Pu at 60% fuel volume and lower for the mixture of RG-Pu and WG-Pu at 65% fuel volume fraction.
Keywords: Long-life PWR, Neutronics, SRAC, Thorium, Uranium, Plutonium, BP
