Public release date: 6-Sep-2009
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Contact: Dianne Stilwell
diannestilwell@me.com
44-795-720-0214
Society for General Microbiology
Making more efficient fuel cells
Bacteria that generate significant amounts of electricity could be used in microbial fuel cells to provide power in remote environments or to convert waste to electricity. Professor Derek Lovley from the University of Massachusetts, USA isolated bacteria with large numbers of tiny projections called pili which were more efficient at transferring electrons to generate power in fuel cells than bacteria with a smooth surface. The team's findings were reported at the Society for General Microbiology's meeting at Heriot-Watt University, Edinburgh, today (7 September).
The researchers isolated a strain of Geobacter sulfurreducens which they called KN400 that grew prolifically on the graphite anodes of fuel cells. The bacteria formed a thick biofilm on the anode surface, which conducted electricity. The researchers found large quantities of pilin, a protein that makes the tiny fibres that conduct electricity through the sticky biofilm.
"The filaments form microscopic projections called pili that act as microbial nanowires," said Professor Lovley, "using this bacterial strain in a fuel cell to generate electricity would greatly increase the cell's power output."
The pili on the bacteria's surface seemed to be primarily for electrical conduction rather than to help them to attach to the anode; mutant forms without pili were still able to stay attached.
Microbial fuel cells can be used in monitoring devices in environments where it is difficult to replace batteries if they fail but to be successful they need to have an efficient and long-lasting source of power. Professor Lovley described how G. sulfurreducens strain KN400 might be used in sensors placed on the ocean floor to monitor migration of turtles.
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Monday, September 7, 2009
Using waste to recover waste uranium
Public release date: 6-Sep-2009
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Contact: Dianne Stilwell
diannestilwell@me.com
44-795-720-0214
Society for General Microbiology
Using waste to recover waste uranium
Using bacteria and inositol phosphate, a chemical analogue of a cheap waste material from plants, researchers at Birmingham University have recovered uranium from the polluted waters from uranium mines. The same technology can also be used to clean up nuclear waste. Professor Lynne Macaskie, this week (7-10 September), presented the group's work to the Society for General Microbiology's meeting at Heriot-Watt University, Edinburgh.
Bacteria, in this case, E. coli, break down a source of inositol phosphate (also called phytic acid), a phosphate storage material in seeds, to free the phosphate molecules. The phosphate then binds to the uranium forming a uranium phosphate precipitate on the bacterial cells that can be harvested to recover the uranium.
This process was first described in 1995, but then a more expensive additive was used and that, combined with the then low price of uranium, made the process uneconomic. The discovery that inositol phosphate was potentially six times more effective as well as being a cheap waste material means that the process becomes economically viable, especially as the world price of uranium is likely to increase as countries move to expand their nuclear technologies in a bid to produce low-carbon energy.
As an example, if pure inositol phosphate, bought from a commercial supplier is used, the cost of this process is £1.72 per gram of uranium recovered. If a cheaper source of inositol phosphate is used (eg calcium phytate) the cost reduces to £0.09 for each gram of recovered uranium. At 2007 prices, uranium cost £0.211/g; it is currently £0.09/g. These prices make the process economic overall because there is also an environmental protection benefit. Use of low-grade inositol phosphate from agricultural wastes would bring the cost down still further and the economic benefit will also increase as the price of uranium is forecast to rise again.
"The UK has no natural uranium reserves, although a significant amount of uranium is produced in nuclear wastes. There is no global shortage of uranium but from the point of view of energy security the EU needs to be able to recover as much uranium as possible from mine run-offs (which in any case pollute the environment) as well as recycling as much uranium as possible from nuclear wastes," commented Professor Macaskie, "By using a cheap feedstock easily obtained from plant wastes we have shown that an economic, scalable process for uranium recovery is possible".
###
[ Print | E-mail | Share Share ] [ Close Window ]
Contact: Dianne Stilwell
diannestilwell@me.com
44-795-720-0214
Society for General Microbiology
Using waste to recover waste uranium
Using bacteria and inositol phosphate, a chemical analogue of a cheap waste material from plants, researchers at Birmingham University have recovered uranium from the polluted waters from uranium mines. The same technology can also be used to clean up nuclear waste. Professor Lynne Macaskie, this week (7-10 September), presented the group's work to the Society for General Microbiology's meeting at Heriot-Watt University, Edinburgh.
Bacteria, in this case, E. coli, break down a source of inositol phosphate (also called phytic acid), a phosphate storage material in seeds, to free the phosphate molecules. The phosphate then binds to the uranium forming a uranium phosphate precipitate on the bacterial cells that can be harvested to recover the uranium.
This process was first described in 1995, but then a more expensive additive was used and that, combined with the then low price of uranium, made the process uneconomic. The discovery that inositol phosphate was potentially six times more effective as well as being a cheap waste material means that the process becomes economically viable, especially as the world price of uranium is likely to increase as countries move to expand their nuclear technologies in a bid to produce low-carbon energy.
As an example, if pure inositol phosphate, bought from a commercial supplier is used, the cost of this process is £1.72 per gram of uranium recovered. If a cheaper source of inositol phosphate is used (eg calcium phytate) the cost reduces to £0.09 for each gram of recovered uranium. At 2007 prices, uranium cost £0.211/g; it is currently £0.09/g. These prices make the process economic overall because there is also an environmental protection benefit. Use of low-grade inositol phosphate from agricultural wastes would bring the cost down still further and the economic benefit will also increase as the price of uranium is forecast to rise again.
"The UK has no natural uranium reserves, although a significant amount of uranium is produced in nuclear wastes. There is no global shortage of uranium but from the point of view of energy security the EU needs to be able to recover as much uranium as possible from mine run-offs (which in any case pollute the environment) as well as recycling as much uranium as possible from nuclear wastes," commented Professor Macaskie, "By using a cheap feedstock easily obtained from plant wastes we have shown that an economic, scalable process for uranium recovery is possible".
###
Friday, July 3, 2009
Public release date: 2-Jul-2009
Contact: Andreas Willert
andreas.willert@enas.fraunhofer.de
49-371-531-32109
Fraunhofer-Gesellschaft
Printable batteries
This release is available in German.
IMAGE: The small, thin battery comes out of the printer and can be applied to flexible substrates.
Click here for more information.
In the past, it was necessary to race to the bank for every money transfer and every bank statement. Today, bank transactions can be easily carried out at home. Now where is that piece of paper again with the TAN numbers? In the future you can spare yourself the search for the number. Simply touch your EC card and a small integrated display shows the TAN number to be used. Just type in the number and off you go. This is made possible by a printable battery that can be produced cost-effectively on a large scale. It was developed by a research team led by Prof. Dr. Reinhard Baumann of the Fraunhofer Research Institution for Electronic Nano Systems ENAS in Chemnitz together with colleagues from TU Chemnitz and Menippos GmbH. "Our goal is to be able to mass produce the batteries at a price of single digit cent range each," states Dr. Andreas Willert, group manager at ENAS.
The characteristics of the battery differ significantly from those of conventional batteries. The printable version weighs less than one gram on the scales, is not even one millimeter thick and can therefore be integrated into bank cards, for example. The battery contains no mercury and is in this respect environmentally friendly. Its voltage is 1.5 V, which lies within the normal range. By placing several batteries in a row, voltages of 3 V, 4.5 V and 6 V can also be achieved. The new type of battery is composed of different layers: a zinc anode and a manganese cathode, among others. Zinc and manganese react with one another and produce electricity. However, the anode and the cathode layer dissipate gradually during this chemical process. Therefore, the battery is suitable for applications which have a limited life span or a limited power requirement, for instance greeting cards.
The batteries are printed using a silk-screen printing method similar to that used for t-shirts and signs. A kind of rubber lip presses the printing paste through a screen onto the substrate. A template covers the areas that are not to be printed on. Through this process it is possible to apply comparatively large quantities of printing paste, and the individual layers are slightly thicker than a hair. The researchers have already produced the batteries on a laboratory scale. At the end of this year, the first products could possibly be finished.
###
Thursday, May 21, 2009
MIT: Slow growth of nuclear could harm climate efforts
The rate of deployment of new nuclear power plants around the world has been much slower than needed in order to combat climate change, the Massachusetts Institute of Technology (MIT) said in an update of its in-depth study on the future of nuclear power.
K.S.Parthasarathy
WNN
Energy And Environment
MIT: Slow growth of nuclear could harm climate efforts
21 May 2009
The rate of deployment of new nuclear power plants around the world has been much slower than needed in order to combat climate change, the Massachusetts Institute of Technology (MIT) said in an update of its in-depth study on the future of nuclear power.
The 2003 edition of the Future of Nuclear Power report said "that in order to make a serious contribution to alleviating global climate change, the world would need new nuclear plants with a total capacity of at least a terawatt [1000 gigawatts] by 2050."
In its updated study, MIT says, "Since the 2003 report, interest in using electricity for plug-in hybrids and electric cars to replace motor gasoline has increased, thus placing an even greater importance on exploiting the use of carbon-free electricity generating technologies."
It added, "With regard to nuclear power, while there has been some progress since 2003, increased deployment of nuclear power has been slow both in the United States and globally, in relation to the illustrative scenario examined in the 2003 report."
MIT noted, "While the intent to build new plants has been made public in several countries, there are only few firm commitments outside of Asia, in particular China, India, and Korea, to construction projects at this time. Even if all the announced plans for new nuclear power plant construction are realized, the total will be well behind that needed for reaching a thousand gigawatts of new capacity worldwide by 2050."
In its updated study, MIT says that, compared to 2003, "the motivation to make more use of nuclear power is greater, and more rapid progress is needed in enabling the option of nuclear power expansion to play a role in meeting the global warming challenge." It added, "The sober warning is that if more is not done, nuclear power will diminish as a practical and timely option for deployment at a scale that would constitute a material contribution to climate change risk mitigation."
Construction costs up
The latest study noted that, "Since 2003 construction costs for all types of large-scale engineered projects have escalated dramatically. The estimated cost of constructing a nuclear power plant has increased at a rate of 15% per year heading into the current economic downturn. This is based both on the cost of actual builds in Japan and Korea and on the projected cost of new plants planned for in the United States. Capital costs for both coal and natural gas have increased as well, although not by as much. The cost of natural gas and coal that peaked sharply is now receding. Taken together, these escalating costs leave the situation [of relative costs] close to where it was in 2003."
According to MIT's study, the overnight capital cost of constructing a nuclear power plant is $4000 per kilowatt (kW), in 2007 dollars. This compares with a figure of $2000/kW, in 2002 dollars, given in the original 2003 study.
The updated study says that, applying the same cost of capital to nuclear as to coal and gas, nuclear came out at 6.6 c/kWh, coal at 8.3 cents and gas at 7.4 cents, assuming a carbon charge of $25 per tonne of CO2 on the latter.
[The updated study can be downloaded from MIT's website]
K.S.Parthasarathy
WNN
Energy And Environment
MIT: Slow growth of nuclear could harm climate efforts
21 May 2009
The rate of deployment of new nuclear power plants around the world has been much slower than needed in order to combat climate change, the Massachusetts Institute of Technology (MIT) said in an update of its in-depth study on the future of nuclear power.
The 2003 edition of the Future of Nuclear Power report said "that in order to make a serious contribution to alleviating global climate change, the world would need new nuclear plants with a total capacity of at least a terawatt [1000 gigawatts] by 2050."
In its updated study, MIT says, "Since the 2003 report, interest in using electricity for plug-in hybrids and electric cars to replace motor gasoline has increased, thus placing an even greater importance on exploiting the use of carbon-free electricity generating technologies."
It added, "With regard to nuclear power, while there has been some progress since 2003, increased deployment of nuclear power has been slow both in the United States and globally, in relation to the illustrative scenario examined in the 2003 report."
MIT noted, "While the intent to build new plants has been made public in several countries, there are only few firm commitments outside of Asia, in particular China, India, and Korea, to construction projects at this time. Even if all the announced plans for new nuclear power plant construction are realized, the total will be well behind that needed for reaching a thousand gigawatts of new capacity worldwide by 2050."
In its updated study, MIT says that, compared to 2003, "the motivation to make more use of nuclear power is greater, and more rapid progress is needed in enabling the option of nuclear power expansion to play a role in meeting the global warming challenge." It added, "The sober warning is that if more is not done, nuclear power will diminish as a practical and timely option for deployment at a scale that would constitute a material contribution to climate change risk mitigation."
Construction costs up
The latest study noted that, "Since 2003 construction costs for all types of large-scale engineered projects have escalated dramatically. The estimated cost of constructing a nuclear power plant has increased at a rate of 15% per year heading into the current economic downturn. This is based both on the cost of actual builds in Japan and Korea and on the projected cost of new plants planned for in the United States. Capital costs for both coal and natural gas have increased as well, although not by as much. The cost of natural gas and coal that peaked sharply is now receding. Taken together, these escalating costs leave the situation [of relative costs] close to where it was in 2003."
According to MIT's study, the overnight capital cost of constructing a nuclear power plant is $4000 per kilowatt (kW), in 2007 dollars. This compares with a figure of $2000/kW, in 2002 dollars, given in the original 2003 study.
The updated study says that, applying the same cost of capital to nuclear as to coal and gas, nuclear came out at 6.6 c/kWh, coal at 8.3 cents and gas at 7.4 cents, assuming a carbon charge of $25 per tonne of CO2 on the latter.
[The updated study can be downloaded from MIT's website]
Will this development help countries which have difficulties in getting electric power due to the peculiarities of geography?
K.S.Parthasarathy
WNN
New Nuclear
Assembly of Russian floating plant starts
20 May 2009
A ceremony has been held to mark the start of the assembly of the world's first floating nuclear power plant in St Petersburg, Russia. Construction had earlier been transferred from Severodvinsk.
The keel was originally laid for the first floating plant - the Akademik Lomonosov - at the Sevmash shipyard in Severodvinsk in April 2007. However, in 2008, Rosatom said that it was to transfer its construction to the Baltiysky Zavod shipbuilding company in Saint Petersburg because Sevmash was inundated with military contracts.
Click to enlarge
Five floating reactors could go to Gazprom to power oil and
gas extraction in Kola and Yamal, with four more used in
northern Yakutia in connection with mining operations. Seven
or eight units could be produced by 2015. (Click to enlarge)
A contract was signed on 27 February 2009 between Rosatom and the Baltiysky Zavod shipyard for completion of the plant. The contract was valued at almost 10 billion roubles ($315 million). A new keel has now been laid at Saint Petersburg for the first floating plant. As part of the contract, Baltiysky Zavod will receive the incomplete floating plants started by Sevmash.
The first plant will house two 35 MW KLT-40S nuclear reactors, similar to those used in Russia's nuclear powered ice breakers, and two generators, and will be capable of supplying a city of 200,000 people. OKBM will design and supply the reactors, while Kaluga Turbine Plant will supply the turbo-generators.
The Akademik Lomonosov was originally destined for the Archangelsk industrial shipyard, which is near to Severodvinsk in northwestern Russia, but the vessel is now destined for Vilyuchinsk, in the Kamchatka region in Russia's far east.
Baltiysky Zavod is to complete the floating plant in 2011. It should then be ready for transportation by the second quarter of 2012 and is set to be handed over to Energoatom by the end of 2012. Rosatom is planning to construct seven further floating nuclear power plants in addition to the one now under construction, with several remote areas under consideration for their deployment. Gazprom is expected to use a number of the floating units in order to exploit oil and gas fields near the Kola and Yamal Peninsulars.
Speaking at the ceremony, Sergey Obozov, director general of Energoatom, said that construction of a second floating plant may start in the autumn of 2010. He said, "We already have agreement with the authorities of Chukotka to station the plant in Pevek."
K.S.Parthasarathy
WNN
New Nuclear
Assembly of Russian floating plant starts
20 May 2009
A ceremony has been held to mark the start of the assembly of the world's first floating nuclear power plant in St Petersburg, Russia. Construction had earlier been transferred from Severodvinsk.
The keel was originally laid for the first floating plant - the Akademik Lomonosov - at the Sevmash shipyard in Severodvinsk in April 2007. However, in 2008, Rosatom said that it was to transfer its construction to the Baltiysky Zavod shipbuilding company in Saint Petersburg because Sevmash was inundated with military contracts.
Click to enlarge
Five floating reactors could go to Gazprom to power oil and
gas extraction in Kola and Yamal, with four more used in
northern Yakutia in connection with mining operations. Seven
or eight units could be produced by 2015. (Click to enlarge)
A contract was signed on 27 February 2009 between Rosatom and the Baltiysky Zavod shipyard for completion of the plant. The contract was valued at almost 10 billion roubles ($315 million). A new keel has now been laid at Saint Petersburg for the first floating plant. As part of the contract, Baltiysky Zavod will receive the incomplete floating plants started by Sevmash.
The first plant will house two 35 MW KLT-40S nuclear reactors, similar to those used in Russia's nuclear powered ice breakers, and two generators, and will be capable of supplying a city of 200,000 people. OKBM will design and supply the reactors, while Kaluga Turbine Plant will supply the turbo-generators.
The Akademik Lomonosov was originally destined for the Archangelsk industrial shipyard, which is near to Severodvinsk in northwestern Russia, but the vessel is now destined for Vilyuchinsk, in the Kamchatka region in Russia's far east.
Baltiysky Zavod is to complete the floating plant in 2011. It should then be ready for transportation by the second quarter of 2012 and is set to be handed over to Energoatom by the end of 2012. Rosatom is planning to construct seven further floating nuclear power plants in addition to the one now under construction, with several remote areas under consideration for their deployment. Gazprom is expected to use a number of the floating units in order to exploit oil and gas fields near the Kola and Yamal Peninsulars.
Speaking at the ceremony, Sergey Obozov, director general of Energoatom, said that construction of a second floating plant may start in the autumn of 2010. He said, "We already have agreement with the authorities of Chukotka to station the plant in Pevek."
Bacteria with a built-in thermometer
Enigmatic features of tiny creatures
Parthasarathy
[ Public release date: 20-May-2009
Contact: Dr. Bastian Dornbach
bastian.dornbach@helmhotz-hzi.de
49-053-161-811-407
Helmholtz Association of German Research Centres
Bacteria with a built-in thermometer
Researchers at the Helmholtz Center demonstrate how bacteria measure temperature and thereby control infection
Researchers in the "Molecular Infection Biology group" at the Helmholtz Centre for Infection Research (HZI) in Braunschweig and the Braunschweig Technical University could now demonstrate for the first time that bacteria of the Yersinia genus possess a unique protein thermometer – the protein RovA - which assists them in the infection process. RovA is a multi-functional sensor: it measures both the temperature of its host as well as the host's metabolic activity and nutrients. If these are suitable for the survival of the bacteria, the RovA protein activates genes for the infection process to begin. These results have now been published in the current online edition of the PLoS Pathogens science magazine.
Yersinia can trigger various different diseases: best well-known is the Yersinia pestis type which caused the Plague in medieval times. This led to the death of around a third of Europe's population. The Yersinia enterocolitica and Yersinia pseudotuberculosis species cause an inflammation of the intestines following food poisoning: the bacteria infect the cells of the intestines, leading to heavy bouts of diarrhoea. The Yersinia bacteria contain invasin as a surface protein to help them penetrate the intestinal cells. The immune cells quickly identify this so-called virulence factor as a danger and launch an immune response. To avoid this, the bacteria quickly lose the invasin soon after entering the body. The germs then adapt their metabolism and feed on the nutrients prepared by the host cells. They also produce substances which kill off the body's defence cells, such as phagocytes. Little was known about how Yersinia is able to regulate these individual stages of infection until now.
Researchers at the HZI, led by Petra Dersch, have now identified how these mechanisms work. The RovA protein plays a key role. The protein reads the temperature for the bacteria. Depending on the environment of the bacteria, this protein either contains the factors required for the infection to begin or else adapts to life within the host. "The functioning of RovA in this way is unique among bacteria," says Petra Dersch.
If inhabiting an environment of around 25°C, the protein RovA ensures that the Yersinia bacteria form invasin as a surface protein. This ensures that the Yersinia can penetrate the intestinal cells immediately upon reaching the 37°C intestine via food. In this warm environment, the RovA alters its form and de-activates the gene for invasin production. Without invasin on their surface, the Yersinia bacteria are invisible to the body's immune system. In its new form, the RovA can now activate other genes in the bacteria to adapt the Yersinia metabolism to that of the host.
Until now, little was known about RovA and the fact that it reacts to temperature. Researchers were presented with a puzzle: "We have long been searching for the mechanisms which regulate RovA activity," says Petra Dersch. "It was therefore all the more surprising to discover that RovA controls various processes by acting as a thermometer and as such is self-regulating". At the end of the process, the RovA is responsible for its own decomposition. If the initial stages of infection prove successful, the Yersinia bacteria no longer need the RovA: in its modified form at 37°C, enzymes in the bacteria can attack and break down the RovA.
###
Original article: Herbst K, Bujara M, Heroven AK, Opitz W, Weichert M, et al. 2009 Intrinsic Thermal Sensing Controls Proteolysis of Yersinia Virulence Regulator RovA. PLoS Pathog 5(5): e1000435. doi:10.1371/journal.ppat.1000435
Parthasarathy
[ Public release date: 20-May-2009
Contact: Dr. Bastian Dornbach
bastian.dornbach@helmhotz-hzi.de
49-053-161-811-407
Helmholtz Association of German Research Centres
Bacteria with a built-in thermometer
Researchers at the Helmholtz Center demonstrate how bacteria measure temperature and thereby control infection
Researchers in the "Molecular Infection Biology group" at the Helmholtz Centre for Infection Research (HZI) in Braunschweig and the Braunschweig Technical University could now demonstrate for the first time that bacteria of the Yersinia genus possess a unique protein thermometer – the protein RovA - which assists them in the infection process. RovA is a multi-functional sensor: it measures both the temperature of its host as well as the host's metabolic activity and nutrients. If these are suitable for the survival of the bacteria, the RovA protein activates genes for the infection process to begin. These results have now been published in the current online edition of the PLoS Pathogens science magazine.
Yersinia can trigger various different diseases: best well-known is the Yersinia pestis type which caused the Plague in medieval times. This led to the death of around a third of Europe's population. The Yersinia enterocolitica and Yersinia pseudotuberculosis species cause an inflammation of the intestines following food poisoning: the bacteria infect the cells of the intestines, leading to heavy bouts of diarrhoea. The Yersinia bacteria contain invasin as a surface protein to help them penetrate the intestinal cells. The immune cells quickly identify this so-called virulence factor as a danger and launch an immune response. To avoid this, the bacteria quickly lose the invasin soon after entering the body. The germs then adapt their metabolism and feed on the nutrients prepared by the host cells. They also produce substances which kill off the body's defence cells, such as phagocytes. Little was known about how Yersinia is able to regulate these individual stages of infection until now.
Researchers at the HZI, led by Petra Dersch, have now identified how these mechanisms work. The RovA protein plays a key role. The protein reads the temperature for the bacteria. Depending on the environment of the bacteria, this protein either contains the factors required for the infection to begin or else adapts to life within the host. "The functioning of RovA in this way is unique among bacteria," says Petra Dersch.
If inhabiting an environment of around 25°C, the protein RovA ensures that the Yersinia bacteria form invasin as a surface protein. This ensures that the Yersinia can penetrate the intestinal cells immediately upon reaching the 37°C intestine via food. In this warm environment, the RovA alters its form and de-activates the gene for invasin production. Without invasin on their surface, the Yersinia bacteria are invisible to the body's immune system. In its new form, the RovA can now activate other genes in the bacteria to adapt the Yersinia metabolism to that of the host.
Until now, little was known about RovA and the fact that it reacts to temperature. Researchers were presented with a puzzle: "We have long been searching for the mechanisms which regulate RovA activity," says Petra Dersch. "It was therefore all the more surprising to discover that RovA controls various processes by acting as a thermometer and as such is self-regulating". At the end of the process, the RovA is responsible for its own decomposition. If the initial stages of infection prove successful, the Yersinia bacteria no longer need the RovA: in its modified form at 37°C, enzymes in the bacteria can attack and break down the RovA.
###
Original article: Herbst K, Bujara M, Heroven AK, Opitz W, Weichert M, et al. 2009 Intrinsic Thermal Sensing Controls Proteolysis of Yersinia Virulence Regulator RovA. PLoS Pathog 5(5): e1000435. doi:10.1371/journal.ppat.1000435
Sunday, April 26, 2009
Hydrogen protects nuclear fuel in final storage
An interesting development in nuclear waste management technology
Dr K.S.Parthasarathy
Public release date: 24-Apr-2009
[ Print | E-mail | Share Share ] [ Close Window ]
Contact: Sofie Hebrand
sofie.hebrand@chalmers.se
46-317-728-464
Swedish Research Council
Hydrogen protects nuclear fuel in final storage
When Sweden's spent nuclear fuel is to be permanently stored, it will be protected by three different barriers. Even if all three barriers are damaged, the nuclear fuel will not dissolve into the groundwater, according to a new doctoral dissertation from Chalmers University of Technology in Sweden.
By Midsummer it will be announced where Sweden's spent nuclear fuel will be permanently stored. Ahead of the decision a debate is underway regarding how safe the method for final storage is, primarily in terms of the three barriers that are intended to keep radioactive material from leaking into the surrounding groundwater.
But according to the new doctoral dissertation, uranium would not be dissolved by the water even if all three barriers were compromised.
"This is a result of what we call the hydrogen effect," says Patrik Fors, who will defend his thesis in nuclear chemistry at Chalmers on Friday. "The hydrogen effect was discovered in 2000. It's a powerful effect that was not factored in when plans for permanent storage began to be forged, and now I have shown that it's even more powerful than was previously thought."
The hydrogen effect is predicated on the existence of large amounts of iron in connection with the nuclear fuel. In the Swedish method for final storage, the first barrier consists of a copper capsule that is reinforced with iron. The second barrier is a buffer of bentonite clay, and the third is 500 meters of granite bedrock. Some other countries have chosen to make the first barrier entirely of iron.
It is known that microorganisms and fissure minerals in the rock will consume all the oxygen in the groundwater. If all three barriers were to be damaged, the iron in the capsule would therefore be anaerobically corroded by the water, producing large amounts of hydrogen. In final storage at a depth of 500 meters, a pressure of at least 5 megapascals of hydrogen would be created.
Patrik Fors has now created these conditions in the laboratory and examined three different types of spent nuclear fuel. All of the trials showed that the hydrogen protects the fuel from being dissolved in the water, even though the highly radioactive fuels create a corrosive environment in the water as a result of their radiation. The reason for the protective effect is that the hydrogen prevents the uranium from oxidizing and converting to liquid form.
Furthermore, the hydrogen makes the oxidized uranium that already exists as a liquid in the water shift to a solid state. The outcome was that the amount of uranium found dissolved in the water, after experiments lasting several years, was lower than the natural levels in Swedish groundwater.
"The hydrogen effect will prevent the dissolution of nuclear fuel until the fuel's radioactivity is so low that it need no longer be considered a hazard," says Patrik Fors. The amount of iron in the capsules is so great that it would produce sufficient hydrogen to protect the fuel for tens of thousands of years.
###
Patrik Fors carried out his experiments at the Institute for Transuranium Elements in Karlsruhe, Germany, in a joint project with Chalmers. The institute is operated by the European Commission. The research was also funded by SKB, the Swedish Nuclear Fuel and Waste Management Company.
The dissertation "The effect of dissolved hydrogen on spent nuclear fuel corrosion" will be publicly defended on April 24 at 10 a.m. Place: Hall KE, Chemistry Building, Kemigården 4, Chalmers University of Technology, Gothenburg, Sweden.
For more information, please contact: Patrik Fors, Nuclear Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology, Sweden
Tel: +46707-696 334 patrik.fors@chalmers.se
Supervisor: Kastriot Spahiu, Adjunct Professor, Department of Chemical and Biological Engineering, Chalmers University of Technology, Sweden
+468-459 8561 Kastriot.spahiu@skb.se
Dr K.S.Parthasarathy
Public release date: 24-Apr-2009
[ Print | E-mail | Share Share ] [ Close Window ]
Contact: Sofie Hebrand
sofie.hebrand@chalmers.se
46-317-728-464
Swedish Research Council
Hydrogen protects nuclear fuel in final storage
When Sweden's spent nuclear fuel is to be permanently stored, it will be protected by three different barriers. Even if all three barriers are damaged, the nuclear fuel will not dissolve into the groundwater, according to a new doctoral dissertation from Chalmers University of Technology in Sweden.
By Midsummer it will be announced where Sweden's spent nuclear fuel will be permanently stored. Ahead of the decision a debate is underway regarding how safe the method for final storage is, primarily in terms of the three barriers that are intended to keep radioactive material from leaking into the surrounding groundwater.
But according to the new doctoral dissertation, uranium would not be dissolved by the water even if all three barriers were compromised.
"This is a result of what we call the hydrogen effect," says Patrik Fors, who will defend his thesis in nuclear chemistry at Chalmers on Friday. "The hydrogen effect was discovered in 2000. It's a powerful effect that was not factored in when plans for permanent storage began to be forged, and now I have shown that it's even more powerful than was previously thought."
The hydrogen effect is predicated on the existence of large amounts of iron in connection with the nuclear fuel. In the Swedish method for final storage, the first barrier consists of a copper capsule that is reinforced with iron. The second barrier is a buffer of bentonite clay, and the third is 500 meters of granite bedrock. Some other countries have chosen to make the first barrier entirely of iron.
It is known that microorganisms and fissure minerals in the rock will consume all the oxygen in the groundwater. If all three barriers were to be damaged, the iron in the capsule would therefore be anaerobically corroded by the water, producing large amounts of hydrogen. In final storage at a depth of 500 meters, a pressure of at least 5 megapascals of hydrogen would be created.
Patrik Fors has now created these conditions in the laboratory and examined three different types of spent nuclear fuel. All of the trials showed that the hydrogen protects the fuel from being dissolved in the water, even though the highly radioactive fuels create a corrosive environment in the water as a result of their radiation. The reason for the protective effect is that the hydrogen prevents the uranium from oxidizing and converting to liquid form.
Furthermore, the hydrogen makes the oxidized uranium that already exists as a liquid in the water shift to a solid state. The outcome was that the amount of uranium found dissolved in the water, after experiments lasting several years, was lower than the natural levels in Swedish groundwater.
"The hydrogen effect will prevent the dissolution of nuclear fuel until the fuel's radioactivity is so low that it need no longer be considered a hazard," says Patrik Fors. The amount of iron in the capsules is so great that it would produce sufficient hydrogen to protect the fuel for tens of thousands of years.
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Patrik Fors carried out his experiments at the Institute for Transuranium Elements in Karlsruhe, Germany, in a joint project with Chalmers. The institute is operated by the European Commission. The research was also funded by SKB, the Swedish Nuclear Fuel and Waste Management Company.
The dissertation "The effect of dissolved hydrogen on spent nuclear fuel corrosion" will be publicly defended on April 24 at 10 a.m. Place: Hall KE, Chemistry Building, Kemigården 4, Chalmers University of Technology, Gothenburg, Sweden.
For more information, please contact: Patrik Fors, Nuclear Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology, Sweden
Tel: +46707-696 334 patrik.fors@chalmers.se
Supervisor: Kastriot Spahiu, Adjunct Professor, Department of Chemical and Biological Engineering, Chalmers University of Technology, Sweden
+468-459 8561 Kastriot.spahiu@skb.se
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