Archive for category Science
Cumbria’s decision to veto an underground repository for the UK shows how hard it is to find a long-term solution
New Scientist – Magazine issue 2904.
18 February 2013 byWilliam M. Alleyand Rosemarie Alley
THERE are 437 nuclear power reactors in 31 countries around the world. The number of repositories for high-level radioactive waste? Zero. The typical lifespan of a nuclear power plant is 60 years. The waste from nuclear power is dangerous for up to one million years. Clearly, the waste problem is not going to go away any time soon.
In fact, it is going to get a lot worse. The World Nuclear Association says that 45 countries without nuclear power are giving it serious consideration. Several others, including China, South Korea and India, are planning to massively expand their existing programmes. Meanwhile, dealing with the waste from nuclear energy can be put off for another day, decade or century.
It’s not that we haven’t tried. By the 1970s, countries that produced nuclear power were promising that repositories would be built hundreds of metres underground to permanently isolate the waste. Small groups of technical experts and government officials laboured behind closed doors to identify potential sites. The results – produced with almost no public consultation – were disastrous.
In 1976, West German politicians unilaterally selected a site near the village of Gorleben on the East German border for a repository, fuelling a boisterous anti-nuclear movement that seems to have no end in sight.
Experts drive issue, general public has lost interest
By Barbro Plogander
Epoch Times Staff
February 11, 2013
Sweden’s solution for storing its nuclear waste suffered a setback recently. While experts are very active, driving the issue, they have failed to excite the interest of the general public.
In Sweden, the new plan for disposing of waste from nuclear power plants is to put it in copper canisters and store it in bedrock. Considering how dangerous the radioactive waste is, corrosion of these canisters is a major issue.
In late January, the Swedish Radiation Safety Authority reported that corrosion had occurred on small copper fragments they had put in oxygen-free water to test them. The report showed that the corrosion process does not stop at a certain point, as previously believed, but continues.
This was the latest setback for the waste-storage method, which has been widely criticized by experts. The news passed without much attention in Sweden.
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Jan-Feb-2013-Vol23-No1, Watershed Sentinel
by Anna Tilman
Nuclear waste, especially nuclear fuel wastes from reactors, also called high-level radioactive wastes, is the greatest danger caused by the nuclear industry. This fuel, otherwise known as irradiated fuel or “spent” fuel, contains hundreds of radioactive elements that are the products of fission in a reactor. Many of them are not found in nature. This fuel is lethal in seconds to anyone nearby. It will leave an indelible mark on the planet for eons.
Determined to allay long-standing public concerns about this waste, the nuclear industry and their supportive governments worldwide have advocated Deep Geological Repositories (DGRs) as the “final solution” to safely contain these wastes. To date, no DGR for spent fuel has been built or is operating anywhere in the world.
There is no assurance that this waste could be safely and permanently contained in DGRs. No computer models can accurately take into account all the complexities that could be encountered from burying this deadly waste deep underground or provide assurance that, over a million or more years, radioactivity would not be released. Natural systems are far too complicated and ever-changing for a complete, accurate model to be valid, or even possible.
Corrosion of copper in distilled water without molecular oxygen and the detection of produced hydrogen
In this report, results are presented for copper which has been exposed to pure anoxic water in the temperature interval of 21° C to 55 °C up to a total of 19 000 hours. Characterisations of copper surfaces after exposure have been performed ex-situ, meaning after termination of the experiment and exposing the specimen to normal atmospheric environment.
Ideally characterisation of surfaces should have been performed with the specimens in the reaction chamber without oxygen supply but this was not possible in the experimental set-up used. Thus it cannot be excluded that formed species on surfaces could have been altered during handling of specimens between exposure and surface analysis.
The results from the surface analysis of exposed copper specimens indicate that the reaction products are predominately comprised of oxide and hydroxide. Furthermore, based on the visual appearance, the reaction products formed are solid and of a three dimensional character. Moreover, depth analysis by ion sputtering shows that hydrogen is present at greater depth from the surface and inwards compared to oxygen. This indicates that corrosion of copper in anoxic water involves a mechanism in which hydrogen atoms present in water molecules form hydrogen gas which partly dissociate and diffuse into the copper metal as hydrogen atoms
Author: G. Hultquist, M.J. Graham, O. Kodra, S. Moisa, R. Liu, U. Bexell and J.L. Smialek
Publication date: 13-01-18
No of pages: 28
Possible to order: Yes
Price per publication: 100 SEK (incl. VAT)
Download: 2013:07 Corrosion of copper in distilled water without molecular oxygen and the detection of produced hydrogen [2836 kb]
Tuesday, January 15, 2013 11:12:55 EST AM
I feel that the Nuclear Waste Management Organization has been reluctant in exposing some of the dangers associated with their design for their proposed deep geological repository. After reading many articles from the NWMO website, in an effort to learn more and become informed, some alarming facts have come to light that I will briefly describe.
Since 2008 the Nuclear Waste Management Organization (NWMO) has commissioned an Independent Technical Review Group (ITRG) consisting of nuclear experts from Sweden, Switzerland, United Kingdom and Canada. The role of the ITRG is to respond to the NWMO’s technical program and make recommendations for improvement and change.
Unfortunately, since 2008, the ITRG reports have been buried deep in the NWMO’s website along with documents about risks and dangers involving a DGR.
The current NWMO DGR design includes an underground cavern with an area of 930 acres at a depth of 500 metres below the surface. The NWMO plan has always been to create a major shaft using a hoist system to bring people, tonnes of explosives, massive mining machinery and the hundreds of thousands of tonnes of highly radioactive waste to cavern depth as well as to bring excavated rock from the cavern to the surface. And up to one hundred years after burial of radioactive used fuel containers, NWMO would rely on the hoist system to raise the dangerous used fuel for possible repackaging or reprocessing.
In its 2011 report, the Independent Technical Review Group stated that “a payload of 75 metric tons would be required to be lowered down the shaft. There is no precedent for handling a payload of this magnitude in a vertical shaft.”
They go on to say that radiological safety could be compromised in the event of a dropped container for which “the programme risk is considerable given the likely requirements for clean-up of dispersed materials and retrieval of a damaged container and its contents. Therefore very high reliability of handling at least 10,000 heavy payloads in a vertical shaft would have to be ensured, which may be beyond conventional mining practice.”
Given the concerns of these highly recognized experts, NWMO should not be exposing citizens of our town to decades of known health and safety risks.
“The ITRG further recommends that NWMO should give careful consideration to the option of using an inclined ramp to transfer used fuel to the repository horizon…” in order to avoid a dropped load accident.
While these recommendations are in line with the standard ramp design planned for the Sweden and Finland DGR’s, it would substantially increase the area of land required to carry out the project and greatly increase the construction and operational cost of a DGR.
Because of the above information, I believe that the NWMO and possibly our town council have some questions to answer before further agreements can be made between the town and NWMO.
Would an inclined ramp design through several layers of sedimentary rock be sufficiently stable or would it risk a collapse during and post construction?
Would an inclined ramp system increase the surface water flow into the DGR jeopardizing the presumably dry limestone at the repository level during and post-construction?
Will NWMO follow the ITRG recommendation and change its design before asking municipalities to continue with there siting process? As of yet, they have not done so.
Should smaller communities such as Saugeen Shores be eliminated from the siting process based on the additional land requirements for an inclined ramp system?
Will the Mayor and town council members hold NWMO accountable for yet another failure to be open and honest with the citizens of this town?
When will NWMO be honest, transparent and clear when communicating with all communities about the risks and costs involved with their proposed DGR project?
According to a December notice distributed by the Canadian Nuclear Safety Commission, the Canadian Standards Association – the folks that set standards to make sure your toasters don’t catch fire and the threads on the bolt will match the threads on the nut – are now the lead agency for developing a standard for dry storage for the highly radioactive nuclear fuel waste generated by nuclear power reactors.
The notice from the CNSC states:
The Canadian Standards Association (CSA) is a membership association serving industry, government, consumers and other interested parties in Canada and the global marketplace. Many CSA energy standards are national standards of Canada and are cited in both federal and provincial regulations. In addition to providing energy standards, the Canadian Standards Association (CSA) also helps to promote a safe and reliable nuclear power industry in Canada through the creation of specific nuclear industry standards.
The CSA is currently seeking your input on a new draft standard relating to the nuclear industry on interim dry storage systems for irradiated fuel.
If you would like to consult and provide comments on this proposed standard, please go to: http://publicreview.csa.ca/Home/Details/513
According to the current draft, the standard will specify “requirements for the site selection, design, construction, commissioning, operation, and planning for decommissioning of dry storage systems. Dry storage systems include facilities, structures, support services, and equipment required for
(a) transferring irradiated fuel
(i) from wet storage to dry storage containers; and
(ii) to a dry storage facility;
(c) storage of irradiated fuel;
(e) retrieval of irradiated fuel from dry storage; and
(f) decommissioning planning.
If you are interested in working with other public interest groups participating in this review, please contact firstname.lastname@example.org.
This paper deals with fuel rod fragmentation during a core meltdown accident in a Nuclear Power Plant. If water is injected on the degraded core to stop the degradation, embrittled fuel rods may crumble to form a reactor debris bed. The size and the morphology of the debris are two key parameters which determine in particular heat transfer and flow friction in the debris bed and as a consequence its coolability. To address this question, a bibliographic survey is performed with the aim of evaluating the size and the surface area of the fragments resulting from fuel rod fragmentation. On this basis, a model to estimate the mean particle diameter obtained in a reflooded degraded core is proposed. Modelling results show that the particle size distribution is very narrow if we only take into account fuel cracking resulting from normal operating conditions. It leads to minimum mean diameters of 2.5 mm (for fuel particles), 1.35 mm (for cladding particles) and 2 mm (for the mixing of cladding and fuel fragments). These results are obtained with fuel rods of 9.5 mm outer diameter and cladding thickness of 570 μm. The particle size distribution is larger if fine fragmentation of the highly irradiated fuel rods during temperature rise is accounted for. This is illustrated with the computation by the severe accident code ASTEC, codeveloped by IRSN abd GRS, of the size of the debris expected to form in case of reflooding of a French 900 MW reactor core during a core meltdown accident.
- Institut de Radioprotection et de Sûreté Nucléaire, IRSN/PSN-RES/SAG/LESAM, Cadarache Nuclear Center, BP 3, 13 115 St Paul Lez Durance cedex, France