During plant operation there is a potential for a loss of forced circulation in the primary heat transport system due to a Loss of Class IV power to an single electrical bus, which leads to a loss of a main heat transport pump, or through a failure of power to multiple busses or to the plant which will lead to the loss of 2 or all 4 pumps. Historically, nuclear safety analysis for these events have adopted bounding assumptions for key parameters to ensure that the outcome of the analysis would envelope those expected during an event, and did not take credit for possible process system mitigation. While this provided conservative estimates of the consequences of these events, and met the analysis requirements for licensing at the time, the existing analyses do not provide any knowledge on true response of the plant. The objective of this work is to perform best estimate and deterministic analyses, including the impact of anticipated Reactor Regulating System actions for Loss of Flow (LOF) events in a CANDU station, and to provide the sensitivities to process system component availability. This initial work will feed into downstream Best Estimate and Uncertainty (BEAU) which will explicitly account for the uncertainties in the key parameters, and will eventually provide a measure of the true safety margins for these events.
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