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Arsenic found to control uranium contamination

As reported by World Nuclear News, an international team led by the University of Sheffield has discovered that the toxic element arsenic prevents uranium from an abandoned mine in the UK migrating into rivers and groundwater.  The discovery could help in the remediation of former uranium mines and other radioactively contaminated areas around the world, the scientists believe.

The team of scientists – led by the Department of Materials Science and Engineering at the University of Sheffield – studied the uranium and arsenic in the topsoil at the abandoned South Terras uranium mine in Cornwall, England.

The researchers used some of the world’s brightest synchrotron X-ray microscopes – the Swiss Light Source and the USA’s National Synchrotron Light Source – to unearth what is believed to be the first example of arsenic controlling uranium migration in the environment.  These microscopes use intense X-ray beams to focus on a spot just one-millionth of a metre in diameter.

“We use synchrotron X-rays to identify and isolate the microscopic uranium particles within the soils and determine their chemical composition and mineral species,” said co-author of the study, Neil Hyatt.  “It’s like being able to find tiny uranium needles in a soil haystack with a very sensitive metal detector.”

Source: © Claire Corkhill
The abandoned South Terras mine in Cornwall where uranium was mined until 1930

According to the study – published on 14 December in Nature Materials Degradation – ore extraction processes and natural weathering of rock at the South Terras mine has led to the proliferation of other elements during degradation, particularly arsenic and beryllium, which were found in significant concentrations.  The arsenic and uranium were found to have formed the highly insoluble secondary mineral metazeunerite.

“Significantly, our data indicate that metazeunerite and metatorbernite were found to occur in solid solution, which has not been previously observed at other uranium-contaminated sites where uranyl-micas are present,” the study says.

Claire Corkhill, lead author of the study, said: “Locking up the uranium in this mineral structure means that it cannot migrate in the environment.”

The researchers concluded that this process at South Terras – which operated between 1873 and 1930, producing a total of 736 tonnes of uranium – is the result of a set of “rather unique” geological conditions.  “To identify this remediation mechanism at other sites, where arsenic and uranium are key co-contaminants, further detailed mineralogical assessments are required,” they said.  “These should be considered as an essential input to understand the ultimate environmental fate of degraded uranium ore.”

“The study has far-reaching implications, from the remediation of abandoned uranium mines across the world, to the environmental clean-up of nuclear accidents and historic nuclear weapons test sites,” according to the scientists.  “It also shows the importance of local geology on uranium behavior, which can be applied to develop efficient clean-up strategies.”

Innovations in Pipeline Design: Leak-proof technology

By Dema Mamon, M.Sc.Pl, BES and John Nicholson, M.Sc., P.Eng.

In Canada, getting approval to construct an oil pipeline has become increasingly difficult.  Every oil pipeline incident that involves a leak and subsequent clean-up is widely covered in the media,  providing fuel for pipeline opponents that call an end to the construction of new pipelines.

Abacus Data Inc., an Ottawa-based research firm, has been tracking public opinion on the construction of new pipeline capacity and has found some interesting trends.  Since 2014, polling has shown that the negative view of building new oil pipelines has remained steady at 21 to 22% range.  However, there was a drop in the positive attitude amongst Canadians toward building new pipelines – from 58% in 2014 to 44% in 2017.  Over that three year span, a good proportion of Canadians who once viewed building new pipeline capacity with a positive attitude have shifted to a neutral view.  The neutral view on oil pipelines have grown from 20% in 2014 to 36% in 2017.

There can be many theories to explain the three year shift in public opinion on new oil pipelines.  One plausible theory is that oil spills from pipelines typically make headline news, thus leaving an impression in the minds of Canadians the perhaps pipelines are not as safe as the industry states.  Oil leaks from pipelines damage the environment, are costly to clean-up, and fuel public opinion that pipelines are not safe.

One way to eliminate the perception that building new oil pipelines is bad for the environment and shift public opinion in favour of such projects is to build pipelines that don’t leak.  However, is it even possible to build leak-proof pipelines?

Are Double-Walled Pipelines the Answer?

One logical idea for building leak-proof pipelines is for them to be double-walled.  The outer wall would serve as protection from external damage.  The technology does exist to construct double-walled pipelines and they are used in certain circumstances such as when there is a large temperature difference between the liquid in the pipe and the surrounding environment.

Double-walled pipelines are not considered the cure-all by some in the industry.  Those resistant to the use of double-walled pipelines note that in some instances, it may be more cost effective to protect pipelines from the potential of external damage by burying them or placing slabs over them in higher risk areas.  Furthermore, it can be more difficult to monitor a double-walled pipeline and an outer pipe interferes with the maintenance of the inner pipe.

At the University of Calgary, researchers believe their two-walled pipeline design and monitoring system is the solution to preventing spills.  Although double-walled pipelines have been around since the 1980’s, Thiago Valentin de Oliveira, an electrical and computer-engineering master’s student, and Martin Mintchev, an engineering professor, say that their design is superior.

The U of Calgary researchers designed and constructed their prototype to consist of a typical steel inner layer with either a steel or plastic outer layer.  There is an air gap between inner and outer pipeline contains the oil that leaks from the inner pipeline leak.  The real innovation developed by the U of Calgary is the segmentation of the inter-pipe space and the inclusion of a linear wireless network linking the segments.  With the segmentation, a leak of oil from the inner pipe enters the air gap between the two pipes and is contained in a section of pipe.  Wireless pressure sensors between the two walled layers detect the pressure build up and send an alert to the pipeline control staff.

 

If commercially implemented, the U of Calgary system would allow pipeline operators with the means of quickly shutting down the pipeline when a leak was detected into the outer pipeline and crews could be dispatched to make repairs.  The oil that leaked from the inner pipe would be contained in the air gap between the two pipes and be confined to one section of the pipeline.

The U of Calgary researchers estimate that their design would result in an additional 25% in the capital cost of building pipelines.  They believe this cost could be reduced if the outer pipeline material was composite materials or plastic.

Is Advanced Monitoring the Solution?

Also in Alberta, a Calgary-based firm, HiFi Engineering, recently announced that it has developed an innovative pipeline leak detection system.  Dubbed High-Fidelity Dynamic Sensing (HDS™), the monitoring system can spot the exact location of a leak in a pipeline within seconds of it occurring.  The system continuously monitors temperature, sonic and ultrasonic acoustics, and vibration and strain.  Any anomaly in the measurements results in an alert being sent to the pipeline company control room.

Hifi Engineering’s High Fidelity Dynamic Sensing (HDS) technology is being called the ‘ears of pipeline monitoring.’

The system works utilizing fiber optic cables that run the length of the pipeline.  A laser beam is sent down the length of the optic cable and sends signals back that provide a multitude of information to the pipeline control room.

TransCanada Pipelines Corporation has already installed the HiFi HDS™ monitoring system in sections of the Keystone XL oil pipeline that runs from Canada to the U.S.  Also, Enbridge employs the technology in its new northern Alberta pipeline.

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About the Authors

Dema is a graduate of York University’s Bachelor in Environmental Studies program (2008) and the University of Toronto’s Masters of Science in Planning Programme (2010). She is currently pursuing her Canada Green Building Council’s Leadership in Energy and Environmental Design’s Green Associate certification. Her research interests include environmental conservation, green infrastructure, and sustainability. She can be reached at dema.mamon@gmail.com.

John Nicholson is the editor of Hazmat Management Magazine.  He has over 25 years of experience in the environmental and cleantech sectors.  He is a registered professional engineer in the Province of Ontario and has a M.Sc. in environmental engineering.  His professional experience includes time at a large engineering consulting firm, a major Canadian law firm, and the Ontario Ministry of the Environment and Climate Change.