Belgium: Breakthrough in Nuclear Waste Transmutation Technology
January 16, 2012 • 2:43AM

An international research team took an important step this week toward proving that an unusual combination of a nuclear reactor and a particle accelerator could be used to transmute and eliminate highly radioactive and long-lived nuclear waste produced in conventional nuclear reactors. The breakthrough shows that nuclear "waste" is really a valuable resource, not something to be feared.

On January 11, in Paris, researchers from Belgium's Nuclear Research Center (SCK-CEN) in Mol and France's Center for National Scientific Research (CNRS) and Atomic Energy Commission (CEA), reported that they had successfully operated a lead-cooled research reactor by boosting its nuclear reactions with an externally produced beam of neutrons. The reactor, constructed in Belgium, is called Guinevere.

Such a set-up is known as an accelerator-driven system (ADS). An ADS reactor is designed to contain too little fissile material in its core to sustain a nuclear chain reaction, a condition known as "subcritical." The design is very safe, since cutting the source of neutrons is sufficient to stop the nuclear reaction. To make the reactor run, extra neutrons must be supplied from another source, such as a proton beam hitting a heavy metal target. That generates neutrons in a process called spallation.

The ADS concept is almost as old as nuclear power itself, but the idea gained more ground in the 1980s when Nobel Laureate, particle physicist Carlo Rubbia, the head of European Center for Nuclear Research (CERN) in Geneva, proposed building an ADS to generate electricity, which he dubbed the energy amplifier. Since then, most research has focussed on using an ADS to transmute high-level nuclear waste into less harmful material and new usable materials.

"What is unique in the Guinevere experiment is that we are reproducing exactly the characteristics of an ADS on an industrial scale," says Hamid Aït Abderrahim, deputy director of SCK-CEN. Guinevere, based on a very small, 1-kilowatt lead-cooled reactor, is a scaled-down model of a much larger ADS, called Myrrha (Multipurpose Hybrid Research Reactor for High-tech Applications), whose construction will start in 2015.

Myrrha is assembled by France's CNRS and managed by Belgium's SCK-CEN, not far from Antwerp. The overall project is supported by 12 other European laboratories and the European Commission.

Myrrha will be able to produce radioisotopes for medical purposes, and doped silicon for semiconductors, but its research functions are particularly well suited to investigate transmutation. When realized on an industrial scale, transmutation will greatly simplify the permanent geologic disposal of radioactive waste. Myrrha can also be used to test the feasibility of lead fast reactor technology and is seen as complementary to the Jules Horowitz Reactor, a thermal spectrum reactor under construction in Cadarache, France.

The total cost of Myrrha has been put at EU960 million, with 40% of this coming from the Belgian government. SCK-CEN is looking to set up an international consortium to ensure additional financing.

Also, in October 2010, Chinese Prime Minister Wen Jiabao and Belgium's Prime Minister Yves Leterme signed an agreement of understanding on collaboration in nuclear research between SCK-CEN and the Chinese Academy of Sciences, focusing on the Myrrha project. "The Chinese see Myrrha as a research infrastructure for preparing the solution to treat their nuclear waste," according to a joint statement on the agreement.

The Sino-Belgian agreement also defines the context for construction of a pilot plant to produce mixed oxide nuclear fuel (MOX) and for the use of MOX in Chinese nuclear reactors. A commercial agreement including technology transfer and technical assistance could soon follow, according to Belgian partners Belgonucleaire, SCK-CEN, and Tractebel. The plant would be built by the China National Nuclear Corporation (CNNC), with the support of the Belgian companies.

Belgium has a wealth of experience in MOX fuel development and production dating back to 1960, including 20 years of industrial MOX production at Belgonucleaire's Dessel plant which produced 35 tons per year from 1986 to 2006. MOX has been in use in Belgium's nuclear power plants since 1995.

China's nuclear plans would see it operating about 200 large reactors in 20 years time, and it wants to limit the amount of imported uranium required to support them. For that reason it is very keen to close the nuclear fuel cycle by reprocessing used fuel to recover useful uranium and plutonium, and then to recycle the plutonium in MOX.