Structural response of calandria tube to a spontaneous rupture of the pressure tube

The primary function of calandria tubes in a CANDU * pressurized heavy water reactor is to minimize the heat loss from the heat transport system to the cool moderator by providing an insulating gas annulus. Circulation of an inert gas in the annulus also provides an effective leak detection capability. During certain postulated accident scenarios in which the pressure tube ruptures, the surrounding CT is subjected to transient pressure loading due to discharge of the coolant into the annulus. Experimental investigation of the calandria tube response under such a scenario has indicated that the Interaction of the two tubes is a complex phenomenon. Some of the main observed structural deformations during the tests are reported in this paper. Theoretical models developed to simulate these observed responses are also reported.