The Prototype Fast Breeder Reactor (PFBR) is a 500 MWe sodium-cooled, fast breeder reactor that is being constructed at the same site as the Madras Atomic Power Station in Kokkilamedu, near Kalpakkam, in Tamil Nadu state, India. The Indira Gandhi Centre for Atomic Research (IGCAR) is responsible for the design of this reactor, the Advanced Fuel Fabrication Facility at the Bhabha Atomic Research Centre in Tarapur is responsible for MOX fuel fabrication and BHEL is providing technology and equipment for construction of the reactor. The facility builds on the decades of experience gained from operating the lower power Fast Breeder Test Reactor (FBTR). At first, the reactor's construction was supposed to be completed in September 2010, but there were several delays. The Prototype Fast Breeder Reactor is scheduled to be put into service in December 2024, which is more than 20 years after construction began and 14 years after the original commissioning date, as of December 2023. The project's cost has doubled from ₹3,500 crore to ₹7,700 crore due to the multiple delays. The construction was completed on 4th March 2024 with commencement of core loading of the reactor hence paving the way for the eventual full utilization of India’s abundant thorium reserves.