Conceptual Design Of Passive Moderator System For Thorium-based Advanced CANDU Reactor

Since 1950s', Canada has developed a new technique on the pressure tubeheavy water reactor named CANDU according to its national situation. Thereare many differences between CANDU and a pressurized water reactor instructure. These differences bring some advantages for CANDU in reactorsafety and security. In order to develop Thorium-based Advanced CANDUReactor (TACR) technique, the Atomic Energy of Canada Ltd(AECL) hascooperated with Tsinghua University. This research work is a part of theproject.In this thesis, a new concept with passive moderator system for TACR isdesigned, and is assessed through analyzing a loss of coolant flow accident(LOFA)by CATHENA Mod3.5c/Rev1, a thermalhydraulic computer codedeveloped by AECL for CANDU.First of all, several kinds of passive residual heat removal systems (PRHR)have been described, and a new conceptual design is completed based on thesystems.The heavy water loop and the light water loop in the moderator systemhave been nodalized. Some important parameters after LOFA, such as thetemperature, the pressure, the mass flow rate of moderator system, arecalculated and analyzed. According to the calculation results, the passivemoderator system is able to cool the core after LOFA.In addition, the methods of using CATHENA and the experience in usingCAHTENA are introduced.