Design of 33 pin annular fuel rod cluster for Advanced Heavy Water Reactor

The Advanced Heavy Water Reactor (AHWR) is a vertical pressure tube type reactor designed for utilizing thorium fuel with boiling light water as coolant and heavy water as moderator. The AHWR has several passive features, the major ones being heat removal through natural circulation, decay heat removal through passive means by the way of isolation condensers and a large heat sink in the form of gravity driven water pool. In the existing design of AHWR, the fuel rod cluster has solid fuel pins. The limitation on it is the Minimum Critical Heat Flux Ratio (MCHFR), which comes from coolant characteristics. In order to improve power output from the AHWR we are trying to design internally and externally cooled annular fuel rod cluster for AHWR. The fuel cluster design would have to be qualified from physics and thermal hydraulic behavior. In order to satisfy the design objectives, a detailed thermal hydraulics and physics simulation has been done.