STUDY ON PRIMARY COOLANT FLOW SYSTEM OF SUPERCRITICAL NA TURAL CIRCULA TlON WA TER REACTOR (SNWR). Design and numerical analysis of aheat exchanger to be operated in a Supercritical Natural Circulation Water Reactor (SNWR)design have been performed. The heat exchanger is a shell and tube counter flow 1-1 fluid flowtype with 2997 tubes. The tubes are made of nickel alloy with 1.09 em inside diameter and 1.27em outside diameter. The height of the tube is 6 m. The SNWR is designed to have 12exchangers. The primary coolant system is integral design in which the reactor core and theheat exchangers are located inside a reactor vessel. In this design, the core is located at thebottom part of the reactor vessel while the heat exchangers are located at upper part of thereactor vessel. The SNWR is a light water reactor using U02 as fuel, light water as coolant andmoderator. The light water is pressurized at 25 MPa and flows through the reactor core and theheat exchangers by natural circulation. The SNWR has the output thermal power of 210 MWth,with the core height of 2 m and the primary coolant flow rate of 164 kg/so For this purpose thechimney height of 3.98 m is necessary. The secondary fluid is pressurized at 20 MPa. Theprimary fluid flows at the shell side while the secondary fluid flows at the tube side of the heatexchangers. The secondary fluid mass flow rate is 147 kg/so The primary coolant (pressurized at25 MPa) enters the heat exchanger at the temperature of 450°C and leaves the heat exchangerat the temperature 350 °C. The secondary fluids (pressurized at 20 MPa) enters the heatexchanger at the temperature of 320°C and leaves the heat exchanger at the temperature 420°C. The results of the numerical calculations show that the natural circulation of SNWR design isadequately stable to maintain the proportionality of the primary coolant mass flow rate to thereactor core heat generation.Kev words: SNWR, supercritical pressure, natural circulation. Ahmad Haikal, Andang Widi Harto, Kutut Suryopartomo; Program Studi Fisika Teknik, Jurusan Teknik Fisika, Fakultas Teknik UGM
