On March 16, 2012 Russia and Vietnam signed an intergovernmental agreement to return HEU spent fuel of the Dalat Nuclear Research Reactor (DNRR) to Russia.
The reactor, operated by the Nuclear Research Institute in Dalat, is a modification of a TRIGA Mark II reactor that began operations in 1963 (data are from a presentation at a 2007 IAEA meeting and a paper presented at the 2002 RERTR meeting). The original reactor was shut down in 1968 and all the fuel removed by 1975. It was redesigned and started again in 1983. The reactor used VVR-M2 fuel assemblies with 36% enriched uranium.
The reactor operated with mixed core - 98 HEU and 6 LEU fuel assemblies - since September 2007. Also in 2007 4.3 kg of fresh HEU fuel was returned to Russia. The NNSA press release about the event incorrectly states that the reactor was fully converted at that time. The conversion was reportedly completed in 2011 - the reactor began operations with LEU core on December 1, 2011.
The work on conversion of the reactor and the return of the fuel to Russia is carried out as part of the Global Threat Reduction Initiative.