Rock-solid radioactive waste
For the first time ever a technology known as synroc will turn liquid radioactive waste into synthetic rock. Just like in nature, where some rock minerals trap radioactive materials (such as uranium and thorium) in their crystal structure.
The idea was that if nature's rocks can safely contain radioactive substances within their structure for millions of years, then surely synthetic rock would be ideal to store man-made radioactive waste.
Designed to mimic the rocks' natural processes, synroc was developed in the late 1970s at the Australian National University and later at ANSTO (the Australian Nuclear Science and Technology Organisation) by a team of scientists.
ANSTO will be the world's first facility to turn liquid waste from molybdenum-99 radioisotope production into synroc. The technology will be in operation within the next three years.
ANSTO's technology has been 10 years in the making, and is now becoming reality by applying it to a molybdenum waste immobilisation project. This is thanks to the dedication and hard work of husband and wife scientist-engineers Dr Erden and Dr Devlet Sizgek, and a team of ANSTO engineers.
The team has nearly finished a full-scale mock-up of the plant, designed to test custom-built equipment needed to process the material. This must be achieved before a real 'hot' cell plant is built and actual radioactive material is handled. Before reaching this current crucial mock-up stage, however, the production process had to be scoped, investigated and refined.
Erden's first ANSTO synroc task was to develop a technology to produce the precursor powders needed to be mixed with the radioactive waste before - using heat and pressure - it could be pressed into synroc.
"We have expert group of scientists in ANSTO who can tailor the chemical composition of synroc to fit the waste to be immobilised," he said.
"My first challenge was to develop the ceramic precursor powder-making process, which is called sol-gel process," Erden explained. "A 'sol' being a colloidal suspension of solid particles in a liquid medium which turns into a 'gel' when the particles link-up to form a semi-solid."
The idea was that if nature's rocks can safely contain radioactive substances within their structure for millions of years, then surely synthetic rock would be ideal to store man-made radioactive waste.
Designed to mimic the rocks' natural processes, synroc was developed in the late 1970s at the Australian National University and later at ANSTO (the Australian Nuclear Science and Technology Organisation) by a team of scientists.
ANSTO will be the world's first facility to turn liquid waste from molybdenum-99 radioisotope production into synroc. The technology will be in operation within the next three years.
ANSTO's technology has been 10 years in the making, and is now becoming reality by applying it to a molybdenum waste immobilisation project. This is thanks to the dedication and hard work of husband and wife scientist-engineers Dr Erden and Dr Devlet Sizgek, and a team of ANSTO engineers.
The team has nearly finished a full-scale mock-up of the plant, designed to test custom-built equipment needed to process the material. This must be achieved before a real 'hot' cell plant is built and actual radioactive material is handled. Before reaching this current crucial mock-up stage, however, the production process had to be scoped, investigated and refined.
Erden's first ANSTO synroc task was to develop a technology to produce the precursor powders needed to be mixed with the radioactive waste before - using heat and pressure - it could be pressed into synroc.
"We have expert group of scientists in ANSTO who can tailor the chemical composition of synroc to fit the waste to be immobilised," he said.
"My first challenge was to develop the ceramic precursor powder-making process, which is called sol-gel process," Erden explained. "A 'sol' being a colloidal suspension of solid particles in a liquid medium which turns into a 'gel' when the particles link-up to form a semi-solid."
 |
Erden (left) and Devlet Sizgek inside the mock-up cell. |
According to Erden, the sol-gel process is not dissimilar to how yogurt and cheese are made. "Milk consists of minute particles of fat and protein suspended in water, then a microbial reaction involving yeast causes the suspended particles to gel into a homogeneous mass," he said.
Following Erden's success making the Synroc precursor powder on an industrial scale, there was then a need to develop another technology: the full-scale equipment required to mix the precursor powder with liquid radioactive material. It was at this time that Erden and Devlet joined forces.
Devlet arrived at ANSTO nearly three years after Erden but was already very familiar with his work. She led the project during the technology development phase.
"Over time the technology was perfected and we refined the process by which we change the liquid waste into a dry powder in a controlled manner, avoiding what we call the 'slurry' phase" she said.
"Being married and working together had its pros and cons, but we believe the pros outweighed the cons," Devlet explained. "Our strong commitment to the project may not have existed had we not been so closely linked."
There was a downside, however. "Because we live under the same roof we naturally talk a lot about work at home," she laughed. "As Project Leader I sometimes had to discuss project matters with Erden over the dinner table!"
Devlet and Erden said the building of the mock-up plant to simulate 'hot cell' operations has been a true team effort. During its development about two dozen people have worked hard to make the mock-up cell a reality.
Erden and Devlet are adamant about the project's Australian roots. "Synroc is based on 100 per cent Australian research," they said. "We may have originally come from Turkey but as far as we are concerned, the science and technology we have conducted is totally Australian, as we now are."
Following Erden's success making the Synroc precursor powder on an industrial scale, there was then a need to develop another technology: the full-scale equipment required to mix the precursor powder with liquid radioactive material. It was at this time that Erden and Devlet joined forces.
Devlet arrived at ANSTO nearly three years after Erden but was already very familiar with his work. She led the project during the technology development phase.
"Over time the technology was perfected and we refined the process by which we change the liquid waste into a dry powder in a controlled manner, avoiding what we call the 'slurry' phase" she said.
"Being married and working together had its pros and cons, but we believe the pros outweighed the cons," Devlet explained. "Our strong commitment to the project may not have existed had we not been so closely linked."
There was a downside, however. "Because we live under the same roof we naturally talk a lot about work at home," she laughed. "As Project Leader I sometimes had to discuss project matters with Erden over the dinner table!"
Devlet and Erden said the building of the mock-up plant to simulate 'hot cell' operations has been a true team effort. During its development about two dozen people have worked hard to make the mock-up cell a reality.
Erden and Devlet are adamant about the project's Australian roots. "Synroc is based on 100 per cent Australian research," they said. "We may have originally come from Turkey but as far as we are concerned, the science and technology we have conducted is totally Australian, as we now are."
No comments:
Post a Comment