Neutronics calculations and characteristic study of the HTTR high temperature test reactor core

• Main Author: 李俊諺
• Other Authors: 梁正宏
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/20809155037079499561

碩士 === 國立清華大學 === 工程與系統科學系 === 101 === The high temperature test reactor (HTTR) in Japan is a 30 MW thermal, graphite-moderated, helium-cooled reactor that was built to demonstrate the technological feasibility and advantages of one of the GEN-IV reactors, i.e. the prismatic-type very high temperature gas-cooled reactor (VHTR). The reactor core consists of hexagonal fuel and graphite blocks, and each fuel block has 31/33 fuel rods in which 14 fuel compacts are stacked up to form a fuel rod. Each fuel compact contains about 13000 tiny tri-isotropic (TRISO) coated fuel particles randomly embedded in a graphite matrix. The special configuration of the HTTR core represents challenges to reactor physics calculations including fuel double-heterogeneity, vertical cavity streaming, graphite scattering kernel, etc. The suitable modeling of these properties plays a key role for a reliable neutronics analysis of the HTTR. The purpose of this study is to construct the HTTR core models and evaluate their effects on the system multiplication factors, neutron spectra of various regions, reactivity and temperature coefficients, and also fuel burnup performance. Two HTTR core models have been built using the MCNP5/X and SCALE6 code systems, respectively. The preliminary results correspond well to those of the benchmark problems for the HTTR start-up criticality experiment. Furthermore, a series of criticality and depletion calculations are also carried out to investigate the reactor physics features of the HTTR core under various conditions including changing the moderator to fuel ratio、changing the fuel rod radius and changing the fuel material. For the changing fuel material issue, we use the different ratio of Pu/MA material to observe the feature of neutronics. In this thesis, a series of calculation results preform different behavior of neutronics between Pu/MA and LEU.