The 14 th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-14) Log Number: 316 Hilton Toronto Hotel, Toronto, Ontario, Canada, September 25-29, 2011. 1 THERMAL DESIGN ASPECTS OF HIGH-EFFICIENCY CHANNEL FOR SCWRS Wargha Peiman 1 , Igor Pioro 1 , and Kamiel Gabriel 2 1 Faculty of Energy Systems and Nuclear Science 2 Faculty of Engineering and Applied Science University of Ontario Institute of Technology (UOIT) Oshawa, Ontario, Canada wargha.peiman@uoit.ca,igor.pioro@uoit.ca, and kamiel.gabriel@uoit.ca ABSTRACT This paper focuses on thermal-design aspects of a new pressure channel (i.e., High Efficiency Channel) for SuperCritical Water-cooled Reactors. Objectives of this paper are to estimate heat loss from the coolant to the moderator and to investigate the effects of the insulator thickness and moderator pressure on the overall heat loss. In order to meet the objectives of this study, a steady-state one-dimensional heat-transfer analysis was conducted. This analysis showed that heat-loss values vary approximately 30%, depending on the equation used to determine the effective thermal conductivity of the ceramic insulator. However, the upper and lower bounds were determined, which showed that the heat loss per fuel channel was approximately between 70 and 110 kW. The results showed that the optimum thickness of the insulator is between 5 to 7 mm. The effects of the moderator’s operating pressure on the heat loss indicated that the heat loss can be reduced by increasing the operating temperature of the moderator, which can be achieved by increasing the operating pressure of the moderator. NOMENCLATURE A fl flow area, m 2 c p specific heat at constant pressure, J/kg·K ̅  averaged specific heat in cross section,̅ ௣          , J/kg·K D diameter, m D hy hydraulic-equivalent diameter, m G mass flux, kg/m 2 ·s; m/A fl g gravitational acceleration, m/s 2 h heat transfer coefficient, W/m 2 ·K H enthalpy, J/kg k thermal conductivity, W/m·K L length, m m mass-flow rate, kg/s