Models tor Analysing the Radial Heat Transfer In CANDU Reactor Fuel Channels During High-Temperature Loss -of-Coolant Accidents

Abstract

During postulated loss-of-coolant accidents in CANDU reactors with impaired emergency cooling, the decay heat generated in the fuel is transferred first to the pressure tube, then to the calandria tube and then to the surrounding moderator. To predict fuel-bundle temperature under these conditions, the radial heat transfer through the bundle must be modelled accurately. This paper presents heat-transfer models based on an assumed characteristic fuel-element surface temperature. They are easily implemented into the CHAN II lumped heat-capacity code and take little computation time. The results obtained with these models are in good agreement with those obtained with the detailed finite-difference code HOTSPOT.