Advanced Water Reactor.

The Advanced Heavy Water Reactor (AHWR) India is the latest design for a nuclear reactor that will burn thorium next generation in its core fuel. And expected to form the third stage in India's three stage plan of the fuel cycle. Thorium is an element that is three times more abundant than uranium in the world.

The project proposed for the AHWR is that of a heavy water moderated nuclear power reactor that will be the next generation of Pressurised Heavy Water Reactor (PHWR) type. And 'now being developed at Bhabha Atomic Research Centre (BARC) in Mumbai, India and aims to meet the objectives of using thorium fuel cycles for commercial power generation. The AHWR is a vertical pressure tube reactor cooled by boiling light water under natural circulation. A unique feature of this design is a large water tank on top of primary containment vessel, called Gravity Driven Water Pool (GDWP). This shell is designed to perform various functions of passive safety.

The reactor design incorporates advanced technology, along with some positive positive elements of Indian Pressurized Heavy Water Reactors (PHWRs). These features include the type of tubular design pressure, low pressure moderator, by virtue of Supply, several fast-acting shut down systems, and availability of a large heat sink at low temperatures around reactor core. The AHWR incorporates several passive safety features. These include: the removal of core heat by natural circulation, direct injection of Emergency Core Coolant System (ECCS) water in the fuel and the availability of a large inventory of borated water in the head Gravity Driven Water Pool (GDWP) to facilitate the livelihood of the core decay heat removal. The Emergency Core Cooling System (ECCS) injection and cooling can influence (SCRAM) without invoking any active systems or operator action.

The reactor physics design is tuned to optimize the use of thorium-based fuels, creating a slightly negative void coefficient. Fulfilling these requirements is possible through the use of MOX and Tho2 PUOdueTho-2-233UO2 different MOX fuel pins of the cluster itself, and the use of a heterogeneous compound moderator amorphous carbon (in the fuel bundles) and heavy water in 80% -20% volume ratio.

The basic configuration lends itself to considerable flexibility and different options, including those that do not require the use of amorphous carbon based reflectors, are possible without changes in the structure of reactor.