Safety Assessment of Passive Features of Advanced Heavy Water Reactor

Abstract

Advanced Heavy Water Reactor (AHWR) is a vertical, pressure tube type, heavy-water-moderated, boiling light-water-cooled reactor relying on natural circulation for core cooling in all operating and shutdown conditions. In addition, it incorporates various passive systems for decay heat removal, passive valving of isolation condenser at different pressures, passive poison injection system, High pressure passive accumulator, low pressure gravity driven pool, passive containment isolation system and passive containment cooling system. Emphasis is also laid on inherently safe characteristics (e.g. negative void coefficient, large Main Heat Transport (MHT) and deaerator inventory etc). This paper discusses assessment of various passive systems for different governing postulated initiating events in different categories [2]. Loss of Coolant Accident (LOCA) with spectrums of break sizes, station blackout scenarios and reactivity induced accidents are considered in this evaluation.