The Australian Nuclear Science & Technology Organisation’s (ANSTO’s) multi-purpose research reactor has officially returned to power and restarted operations, following a planned shutdown to carry out essential maintenance and upgrades.
The Open Pool Australian Lightwater (OPAL) reactor at the Lucas Heights nuclear medicine precinct was closed in April. OPAL is a state-of-the-art 20 MWt multi-purpose reactor that uses low enriched uranium (LEU) fuel. The $300m OPAL reactor, supplied by Argentina’s INVAP, was opened in 2007 with an estimated design life of 60 years.
The upgrades included replacement of OPAL’s cold neutron source, located next to the reactor core. The three-metre-tall device slows down neutrons as they travel from the OPAL reactor through to the large scientific neutron beam instruments, allowing researchers to look at the structure of materials in atomic detail.
The shutdown also enabled extensive software and hardware upgrades to the First Reactor Protection System, a digital system which monitors the reactor’s critical parameters. This system is the first line of defence allowing the reactor to automatically shut down safely if these parameters are exceeded.
In the years leading up to the planned shutdown, a project team of ANSTO engineers and technicians designed and constructed a full-size mock-up of the reactor to support rehearsals and training activities. ANSTO’s General Manager for the OPAL Reactor, David Vittorio, said this first-of-a-kind project for ANSTO required 10 years of intricate and sequential process planning.
“OPAL is one of the most advanced and reliable research reactors in the world and is the centrepiece to some of ANSTO’s research and commercial operations at Lucas Heights,” he said. “Since OPAL commenced operations 17 years ago, we’ve been in a constant state of forward planning for regular, scheduled maintenance periods to ensure OPAL continues to operate safely, reliably, and efficiently.
In the 12 months prior to the planned shutdown, ANSTO’s project team performed multiple practice runs of the removal and installation of the cold neutron source, and crane manoeuvres using the life-size mock-up. Over 100 bespoke hand tools were also designed and created by ANSTO’s engineering workshop to support a unique range of maintenance activities.
As Australia’s only nuclear reactor, OPAL produces neutrons that form the radioisotopes required for nuclear medicines to diagnose and treat a range of medical conditions and cancers. OPAL also enables the supply of more than half of the global demand for irradiated silicon for use in electronics and green technologies.
Silicon irradiation and nuclear medicine production were temporarily paused during the OPAL reactor shutdown. ANSTO worked with alternative suppliers overseas to import critical nuclear medicine products, providing essential nuclear medicine procedures to patients across Australia. Around 94% of imported nuclear medicine products were supplied to ANSTO in full and on time.
At ANSTO’s Australian Centre for Neutron Scattering (ACNS) adjacent to the OPAL reactor, ACNS Director Dr Jamie Schulz said the replacement cold neutron source will increase the performance to 8 of the centre’s 15 neutron beam instruments. “The neutrons produced by OPAL support our unique facility and scientific instruments, allowing our researchers and industry partners to study the structure and dynamics of samples, such as molecules, polymers, proteins, and viruses,” he noted.
“Approximately 22 litres of liquified deuterium gas at -250°C make up the contents of the cold neutron source, which cools the neutrons and slows them down so they can be used by the unique neutron beam instruments that require ‘cold’ neutrons,” he explained. “The cold neutron source has a design life of 15 years which we’ve been fortunate to maximise our usage of. The replacement cold source is slightly larger and will deliver more cold neutrons to the neutron instruments, leading to a modest increase in the speed of the experiments.”
Researched and written by Judith Perera
