8 May (NucNet): A research reactor in the Netherlands that produces approximately 60% of medical isotopes for European hospitals has been fully converted from using highly-enriched uranium (HEU) fuel to low-enriched uranium (LEU) fuel.
The 45-megawatt high flux reactor at Petten, owned by the Joint Research Center of the European Commission, was started for the first time at 17:00 on 7 May 2006 with a core that solely consists of low-enriched nuclear fuel, said operator the Nuclear Research and Consultancy Group (NRG).
NRG said the conversion of the reactor, on the Netherlands’ west coast, is an “important contribution” to the global effort to limit the use of proliferation-sensitive HEU, which can be used to produce nuclear weapons.
The conversion project began several years ago and was divided into three main stages: a feasibility study, technical studies and licensing procedures.
The first stage resulted in detailed calculation models to optimise the fissile material, by changing its density, to compensate for the lower degree of enrichment. The second stage included a comprehensive professional study, safety analyses, testing of the new nuclear fuel elements, and thermal and hydraulic calculations.
As part of the third stage, NRG applied for an operating licence with permission for the conversion from HEU fuel to LEU fuel already included. That licence was issued in February 2005.
NRG said the conversion had gone smoothly and the impact on isotope production and research programmes being carried out at Petten was minimal. Isotopes produced at Petten are used to treat around 20,000 patients a day. The reactor is also used for research into materials and innovative fuels for a new generation of nuclear power plants, as well as fusion technology and recycling of radioactive waste.
In October 2005, the reactor was started for the first time with four fuel rods and one control rod converted to LEU fuel. The reactor has a total of 33 fuel rods and six control rods. At the time, NRG said the remaining HEU fuel rods and control rods would be gradually replaced by LEU fuel rods.
In January 2005, a study was launched to pave the way for a replacement research reactor at Petten. The existing reactor started operations in 1961 and is expected to operate until about 2015, although it has a longer technical working life. The cost of a new facility has been estimated at around 250 million euros (about 320 million US dollars).
