Apsara is the oldest of India’s research reactors. The reactor was designed by the Bhabha Atomic Research Center (BARC) and built with assistance from the United Kingdom (which also provided the initial fuel supply consisting of 80 percent enriched uranium). Apsara first went critical on 4 August 1956. Apsara is a light water swimming pool-type reactor with a maximum power output of one megawatt thermal (MWt). The reactor burns enriched uranium in the form of aluminum alloyed curved plates. Fuel for the reactor is supplied under contract from the United Kingdom, provided that the fuel is safeguarded. The reactor itself is not under International Atomic Energy Agency safeguards. The Apsara reactor is utilized for various experiments including neutron activation analysis, radiation damage studies, forensic research, neutron radiography, and shielding experiments. The reactor is also used for research and the production of radioisotopes. After nearly half a century of operation, BARC plans to refurbish and modify the aging reactor to test a new indigenous design of a 5-10MWt research reactor.