Sensitivity of heat transfer parameters on the Reaktor Daya Eksperimental - RDE core

Abstract
Center for Nuclear Reactor Safety and Technology (PTRKN) has tasks to perform research and development on the conceptual design of gas cooled reactor (RDE) with small power level of 10 MWt. In line with the development of RDE conceptual design, an analysis on the effects of thermal flow on TRISO fuel temperature distribution in RDE core has been performed. The objective of this research is to analyze the effects of variation of power level, coolant mass flow rate, and pressure on the temperature distribution of TRISO fuel in RDE core that meet safety requirements. This research employs VSOP code, by which the reactor core is divided into 50 components to represent the positions of various material compositions and to model TRISO fuel into 5 layers. The analysis is conducted at the following conditions: power level of 3 MW – 10 MW, flow rate of 1.5 kg/s – 4.32 kg/s, and system pressure of 1 MPa – 3 MPa. For the modelling, reactor parameters, core specification, and TRISO fuel specification as well as TRISO layer data of RDE are used. Based on the analysis results on the effect of helium gas flow, pressure, and reactor power variable on TRISO fuel temperature distribution, it can be concluded that, among these three variables, reactor power gives the most significant effect. The maximum temperatures at kernel and fuel outer layer is 740°C and 736.4°C, respectively. Compared to the temperature distribution resulted between VSOP'94 code and fuel temperature limitation as high as 1600 °C, there is enough safety margin from melting or disintegrating. Therefore, it can be concluded that TRISO fuel is able to contain all radioactive fission products.