CANDU 3 transient analysis using AECL codes

A limited number of transient scenarios were calculated using a computer code suite and input modelling provided by the Atomic Energy of Canada Limited (AECL) for the CANDU 3 design. Emphasis was placed on a large-break loss-of-coolant accident with delays in actuation of the two independent shutdown systems (shutdown rods and liquid poison injection). Although this is expected to be an extremely unlikely scenario, it was studied because of the potential consequences which would result from a positive void coefficient of reactivity. Results indicate that a few second delay in shutdown would result in quickly reaching fuel or cladding melting temperatures, before the emergency core cooling system would be activated. Only small changes in the timing and consequences of the scenario result when several parameters, of potential importance to the progression of the accident, are varied. The severity of the accident is dramatically reduced when it is assumed that one of the two independent shutdown systems function as designed. The results presented in this paper are consistent with related studies performed by AECL and others, and do not reveal any new characteristics or phenomena