India's First Nuclear Reactor was Apsara. It was also the first nuclear reactor in Asia. Apsara went critical at Bhabha Atomic Research Centre (BARC), Trombay on August 4, 1956. It heralded the arrival of India's nuclear energy programme. Dr. Homi Bhabha himself conceptualised the design of the reactor and the reactor was built entirely by Indian engineers in a record time of about 15 months.
Apsara is a swimming-pool-type reactor loaded with enriched uranium as
fuel. The fuel core is suspended from a movable trolley in a pool filled
with water. The pool water serves as coolant, moderator and reflector,
besides providing the shielding.