The first loading of uranium fuel into the OPAL Research Reactor today was an historic moment for Australian science, marking the beginning of a new era in nuclear-based research, said ANSTO Executive Director, Dr Ian Smith.
“Neutron beam research facilities at the OPAL reactor will be in the top three world-wide, and the loading of fuel allows the production of the first neutrons. It’s a very exciting time,” said Dr Smith.
“The fuel loading also marks the beginning of the hot commissioning phase, or Stage B testing, which is split into two parts,” explained Dr Smith.
“The first stage, B1, takes about a week. Nine of the 16 fuel assemblies will be loaded, one by one, until there is sufficient fuel for the reactor to achieve first criticality when the control rods, used to stop the nuclear reaction, are withdrawn. Special start-up instrumentation is used to carefully monitor this operation.
“The second stage, B2, entails loading the remainder of the fuel assemblies, again one by one, until the entire core is in place and completing a series of low power tests.
“During these tests, the reactor’s flux, which determines the neutron beam quality, is measured by placing gold wires in the reactor. The wires are irradiated, removed, and the radiation levels measured to determine the flux level,” said Dr Smith.
“These should verify that the actual flux corresponds to that predicted in the design.”
Full power is not achieved until Stage C when all the necessary flux tests are complete. Stage C is expected to commence
some time in December.
The reactor’s core is about the size and shape of a small bar fridge. The fuel elements are square and about one metre long.
The core sits in the reactor pool at the bottom of 13 metres of water, which acts as a radiation shield and keeps the reactor cool.
At the end of both phases B1 and B2, reports on the commissioning process will be submitted to the regulator ARPANSA**.
Once commissioning of the reactor is complete, neutron beams will be sent to the scientific instruments that will be used to conduct materials research to be applied to food, medicine, industry and biotechnology. Before this can happen, however, ARPANSA must issue a source licence to ANSTO’s Bragg Institute, which is in charge of the neutron beam science instruments currently being constructed for this work.
OPAL is Australia’s third nuclear research reactor and will replace HIFAR, also based on the ANSTO site, which has served the Australian community in supplying radioisotopes and neutron beams for scientific research for the past 50 years.
Published: 11/08/2006