DESIGN AND NEUTRONIC ANALYSIS OF MODULAR GAS COOLED FAST REACTOR USING PARALLELIZATION OF MONTE CARLO METHODS

• Main Author: Raflis, Helen
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/54894
• Institution: Institut Teknologi Bandung

Long life modular reactors are very prospective for the remote areas with small to medium power consumption levels. Gas-cooled Fast Reactor (GFR) is one of six advanced reactors concepts that have been established by the IV generation international forum. Modular GFR was chosen because it has the potential for recycling all actinides and closed fuel cycles as well as implementing a fast reactor, using helium gas as the main coolant, high temperature and low void reactivity effects. The development of the GFR concept design, including the neutronic analysis of the type of fuel pin, fuel assembly and reactor core. The design and analysis of the neutronic Gas-cooled Fast Reactor (GFR) using the parallelization of the Monte Carlo method has been performed in reactor physics point of view. The GFR modeling is simulated with the Monte Carlo method in the full scale and heterogeneous three dimensions (3D) using nuclear data Evaluated Nuclear Data File (ENDF/B-VII.b5). The research used the Monte Carlo code namely the Monte Carlo N-Particle (MCNP6) and OpenMC version 0.12.0. Implementation of parallel computing code is the shared-memory parallelism (OpenMP) and the distributed-memory parallelism (OpenMPI). The GFR design study was performed using natural uranium as the fuel cycle input. In addition, research on long-life CANDLE-GFR core has also been conducted by applying the Spent Nuclear Fuel PWR as the fresh fuel. The preliminary research performed the calculation comparison of MCNP and OpenMC codes that provided a good agreement for the difference infinite criticality of GFR calculations which reached a maximum of 1.0782% in (U-Pu)N fuel. Furthermore, we performed MCNP6 parallelization calculations on the GFR core design, which resulted in a faster calculation time when used more threads. The (U-Pu)C and (U-Pu)N fuels were good candidates for calculation in the GFR study which gave keff more than 1.2 on fissiles containing 20% Pu. Then, research was carried out on the selection of several reflector materials such as pure nickel, pure magnesium, pure lead, Ba2Pb, PbO, BeO, SiC, and Zr3Si2. Reflector candidates have been identified based on nuclear physics parameters, including flux distribution and fission rate, core lifetime, effective multiplication factor, power fraction distribution, neutron leakage, mass evolution of fissile and fertile nuclides, reflector thickness, and neutron energy distribution. The BeO material can be considered as the best reflector candidates for modular GFR based on their reflectivity and power fraction contribution. Then, a research was carried out on the design of the GFR core by optimizing the height-diameter ratio (H/D) and the core-blanket configuration, which implements the Functional Expansion Tally (FET) feature by evaluating the pancake, balance, and tall coretype based on H/D ratio and geometric design on heterogeneous axial, homogeneous, and radial heterogeneous. In this study, the Legendre polynomial feature is applied for axial calculations, while the Zernike polynomial feature is for radial calculations. The results showed that the homogeneous and radial configuration of the pancake and the core balance type provided a more stable flux distribution curve than the axial configuration and the core tall type. Finally, the research of CANDLE-GFR core was carried out using the OpenMC code. The physical parameters that were characterized included the effective multiplication factor, flux distribution, fission rate distribution, and power fraction distribution. The results indicate that the CANDLE-GFR which uses spent nuclear fuel (SNF) PWR reaches an equilibrium core with the neutron flux distribution and the fission rate remaining constant, with movement proportional to the rated power. The power fraction curve shifts and then remains constant in the axial direction until the end of cycle.