CONVERSION OF THE SAFARI-1 RESEARCH REACTOR FROM HEU TO LEU FUEL

The SAFARI-1 research reactor at Pelindaba, Republic of South Africa is a tank-in-pool design operating at 20 MWth. The reactor became operational in March 1965 and has consistently enjoyed an impeccable safety record with a high level of utilization. The reactor was operated with High Enriched Uranium (HEU) fuel until conversion to Low Enriched Uranium (LEU) fuel which was initiated in February 2006 with the irradiation testing of lead test assemblies. The conversion project started with a technical and economic feasibility study in 1994-1995, followed by an updated economic study in 2001 that confirmed the feasibility of converting the reactor to LEU fuel. The Government approval for conversion followed in July 2005. Uranium silicide is being used in the LEU fuel. NECSA has manufactured its own fuel for many years and is developing a capability to manufacture silicide fuel. Fuel plates are currently being procured abroad and assembled locally for the LEU fuel. Although interactions with the South African Nuclear Regulator on conversion (and other improvements) commenced late in 2003, it was decided to separate conversion from the other issues in order to expedite regulatory approval for conversion. To this end a Licensing Philosophy and Strategy for Conversion was submitted to the regulator in August 2007. The initial LEU fuel assemblies were authorized for use on a test basis. A number of fuel assemblies were tested over a two year period but with never more than 2 in the core at any given time. As from August 2008, increasing numbers of LEU fuel assemblies were loaded into the core. In January 2009 the reactor was loaded with a configuration that contained 16 LEU assemblies at different Burnup levels. This paper describes the process that NECSA followed for determining the feasibility of converting SAFARI-1 to LEU fuel and the actual process followed with licensing the conversion of the reactor