Advanced Heavy water Reactor features

ADVANCED HEAVY WATER REACTOR (AHWR)

India is developing the Advanced Heavy Water reactor (AHWR) as the third stage in its plan to utilise thorium to fuel its overall nuclear power program. It is a 300MW vertical pressure tube type reactor using heavy water as moderator and boiling water as coolant in natural circulation mode at low pressure (~ 70 bar).

The calandria has 500 vertical pressure tubes and the coolant is boiling light water circulated by convection. Each fuel assembly has 30 Th-U-233 oxide pins and 24 Pu-Th oxide pins around a central rod with burnable absorber. Burn-up of 24 GWd/t is envisaged. It is designed to be self-sustaining in relation to U-233 bred from Th-232 and have a low Pu inventory and consumption, with slightly negative void coefficient of reactivity.

The major changes from the PHWR design is that AHWR is a thorium fuel based, Light water replaces the high pressure heavy water coolant circulated using a pump .
During its designed plant life of 100 years AHWR will generate 65% of the power from ThO2 based fuel. AHWR is the first of its kind in the world not only because of its most attractive feature of heat removal from the reactor core by natural circulation under all conditions but also due to the fact that it incorporates a host of other passive safety features that are in line with the approach being pursued world over for development of inherently safe reactor system by incorporating safety features that do not call for any human intervention or any active control devices for reactor safety.