Modeling the Quenching of a Calandria Tube Following a Critical Break LOCA in a CANDU Reactor

Abstract

In a critical break LOCA in a CANDU reactor it is possible for the pressure tube to balloon into contact with its calandria tube. Under extreme limiting conditions on the pressure tube temperature at contact and the local moderator subcooling it is possible for transient film boiling on the calandria tube to occur, followed by quenching that returns the tube surface to a rewet condition. A mechanistic model is presented of the quench process associated with destabilization of the vapour film. This work is part of a research program at McMaster University to support new methodology for evaluating fuel channel integrity.