US government chooses ANU's Synroc
By Shelly Simonds Synthetic rock technology invented at the ANU 20 years ago will be used to store plutonium from surplus US nuclear weapons, the Australian Nuclear Science and Technology Organisation (ANSTO) announced early this month. The deal opens up a potential $375 billion market for the product, Synroc, in the nuclear waste disposal industry, ANSTO said. Synroc's success comes more than 20 years after it was invented and patented by the late Professor Ted Ringwood, former director of the Research School of Earth Sciences. In a 1983 interview with the ANU Reporter, Prof Ringwood predicted Synroc would play a major role in the future of nuclear waste management because of its ability to resist leaching at very high temperatures. He said this characteristic was important because it enabled final geologic disposal of Synroc to be carried out deep in the earth, for example at the bottom of a 4-km deep drill hole. The US Department of Energy (USDOE) chose Synroc technology, known in the US as "titanate ceramic", over 70 other wasteforms including European glass storage technologies, as Synroc retains waste more effectively in the presence of ground water. Synroc is an advanced ceramic composed of titanate minerals chosen for their geochemical stability and ability to immobilise the radioactive elements in nuclear waste. It is modelled on the structure of naturally occurring rocks whose constituent minerals immobilise natural radionuclides for timescales of millions of years. The technology was originally developed to store radioactive waste from reprocessing of spent nuclear fuel from power plants. However, most nations have now adopted a "once-through" fuel cycle because the economic justification for reprocessing no longer exists. Accordingly there is no role for Synroc, except in applications such as storing weapons-grade plutonium, said Dr Sue Kesson, of the Research School of Earth Sciences. California-based Lawrence Livermore National Laboratory joined with ANSTO to adapt Synroc to nuclear weapons disposal. The Synroc facility in the United States will be located at a Department of Energy site at the Savannah River in South Carolina. "The real value of the adoption of Synroc for plutonium disposal is that it will thereby obtain accreditation in the US. Not to mention the environmental and non-proliferation benefits," said Dr Kesson. The US Department of Energy will formally license the process as a safe method of nuclear waste disposal, a process worth about $108 million. Once accreditation is obtained, ANSTO will offer Synroc for other radioactive waste immobilisation projects in the US. ANSTO said it maintains close contacts with nuclear engineering companies involved in waste remediation in the US in the hope of opening up future opportunities for the technology.