Turkish Reactor 2 is an upgraded version of the TR-1, Turkey's first nuclear research reactor. The TR-1 was a 1MWt pool-type research reactor that operated from 1962 until 1977. With assistance from the Belgian firm Belgonucléaire, Turkey upgraded the TR-1 to a 5MWt reactor from 1980 to 1981. The TR-2 went critical in December 1981. The main purpose of the TR-2 is the production of isotopes including Tc-99m, I-131, and Ir-192 for medical and industrial uses. [1]

Originally, the TR-2 used fuel enriched to 93% U-235, which was supplied by the French company CERCA. [1] However, under the U.S. National Nuclear Security Administration's Global Threat Reduction Initiative, the TR-2 was subsequently converted to operate on LEU. The reactor's conversion was a gradual process that began in the 1990's. For many years, the reactor operated with a mixed-core of both LEU and HEU. [1] In January 2010, the NNSA removed 5.4 kg of HEU spent fuel from ÇNAEM to the United States. The transfer marked the complete removal of all U.S. origin HEU from Turkey. [2]

Sources:
[1] "Turkey: Power-Balance Concerns," in Nuclear Programmes in the Middle East: In the Shadow of Iran, ed. Mark Fitzpatrick (London: The International Institute for Strategic Studies, 2008), p. 63.
[2] Mehmet Ali Şeflek, "U.S.-Turkey Uranium Transfer from Çekmece Goes Unnoticed," Today's Zaman, 14 April 2010, www.todayszaman.com; "NNSA Announces Highly Enriched Uranium Removed from Turkey," National Nuclear Security Administration, 12 January 2010, www.nnsa.energy.gov.