V — 4.1. List of design basis and beyond design basis accidents

Safety analysis of AHWR has identified an exhaustive list of 43 postulated initiating events [VI-1].

Events considered within the design basis are categorized as follows:

• Decrease in coolant inventory (Loss of coolant accidents);

• Increase in coolant inventory;

• Increase in heat removal;

• Increase in system pressure/Decrease in heat removal;

• Decrease in coolant flow;

• Reactivity anomalies;

• Start-up and shutdown transients;

• AHWR specific events (defuelling, refuelling of AHWR channel).

Events considered beyond the design basis are categorized as follows:

• Multiple failure events;

• Failure of wired shutdown systems and other BDBAs.

Specifically, safety analyses included the analysis of four transients due to failure of the wired (sensors, signal carriers and actuators) systems of the SDS-1 and the SDS-2, with reactor shutdown executed passively, through injection of a poison into the moderator by usage of the system steam pressure.