Temperature Distributions In Cylindrical Plain-Canned Fuel Elements Under Some Transient Conditions

Two critical requirements in the design and operation of natural uranium reactors are the maintenance at all times of the maximum fuel temperature below 600°C, the phase change value and the limiting of the temperature of the can to a value such that its strength and corrosion-resistance properties are adequate. It is necessary, therefore, to examine temperature distributions in the fuel and can under possible significant transient conditions. Three such conditions are numerically examined using the experimental heat transfer data of HUGHES and SLACK (1958). In two cases, the temperature response to a step change in flux and to a typical flux control disturbance, the results show the time-lag effect due to the dominant time constant which has a characteristic value for each fuel-plus-can system. In the third case, the maximum temperature reached during fuel element charging under load is examined.