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

摘要

The SAFARI-1 research reactor at Pelindaba, Republic of South Africa is a tank-in-pool designoperating at 20 MWth. The reactor became operational in March 1965 and has consistentlyenjoyed an impeccable safety record with a high level of utilization. The reactor was operatedwith High Enriched Uranium (HEU) fuel until conversion to Low Enriched Uranium (LEU) fuelwhich was initiated in February 2006 with the irradiation testing of lead test assemblies. Theconversion 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 thereactor to LEU fuel. The Government approval for conversion followed in July 2005. Uraniumsilicide is being used in the LEU fuel. NECSA has manufactured its own fuel for many yearsand is developing a capability to manufacture silicide fuel. Fuel plates are currently beingprocured abroad and assembled locally for the LEU fuel. Although interactions with the SouthAfrican Nuclear Regulator on conversion (and other improvements) commenced late in 2003, itwas decided to separate conversion from the other issues in order to expedite regulatoryapproval for conversion. To this end a Licensing Philosophy and Strategy for Conversion wassubmitted to the regulator in August 2007. The initial LEU fuel assemblies were authorized foruse on a test basis. A number of fuel assemblies were tested over a two year period but withnever more than 2 in the core at any given time. As from August 2008, increasing numbers ofLEU fuel assemblies were loaded into the core. In January 2009 the reactor was loaded with aconfiguration that contained 16 LEU assemblies at different Burnup levels. This paper describesthe process that NECSA followed for determining the feasibility of converting SAFARI-1 toLEU fuel and the actual process followed with licensing the conversion of the reactor