Upper Bound Calculations of Aerosol Vapour Mass Concentrations in a CANDU Fuel Channel during Severe Fuel Damage Accidents

Abstract

During some postulated loss-of-coolant (LOCA) and loss-of- emergency-coolant-injection (LOECI) accidents, temperatures in a CANDU fuel channel may rise high enough to cause a release of vapours of fission products and structural (fuel and cladding) materials into flowing steam- hydrogen mixtures. These vapours will condense into aerosol particles in the cooler parts of the primary heat transport system (PHTS). As the initial part of an overall program to study aerosol formation, transport and associated fission product retention in the PHTS, calculations were performed to estimate the maximum condensable vapour mass concentrations that can occur in a CANDU channel under LOCA-LOECI conditions, These estimates will serve as a guide in designing experiments and defining aerosol processes relevant to CANDU PHTS conditions. The calculations and the obtained results are presented in this paper.