Effect of gas flow in the insulating annulus on fuel channel temperatures in a severe accident in a CANDU reactor

Abstract

The effect of gas flow in the insulting annulus on fuel channel temperatures in a severe accident in a CANDU reactor is analyzed. Results show that pressure tube and fuel temperatures following a severe accident could be reduced considerably using this approach. It is not necessary to provide cooling of the recirculated gas after passage through the fuel channel annulus, since the calculated temperature reductions of fuel bundles and pressure tubes result almost entirely from the improved conductance of the heat flow path to the moderator rather than from heat transport by the helium gas. The technical feasibility and economic justifications for the modification have not been assessed in this study. Such an assessment obviously would be needed before any further conclusions can be reached about this modification.