Michele Kearney's Nuclear Wire

Major Energy and Environmental News and Commentary affecting the Nuclear Industry.
Showing posts with label Sellafield. Show all posts
Showing posts with label Sellafield. Show all posts

Thursday, November 4, 2010

EU battles to lock down radioactive waste forever





Brussels (AFP) Nov 3, 2010 Europe offered new plans Wednesday to lock away forever lethal radioactive waste, but the proposals attacking hopelessly inadequate disposal facilities drew a stinging rebuke from environmentalists. Half a century after atomic power was first produced in Britain, the European Union's nuclear energy-producing countries stand accused of future negligence without a single "deep geological disposal" site equipped to withstand up to an estimated one million years of decay.
As a result, the EU's executive arm tabled for the third time legislative proposals that would see states pushed to build the kind of facility deep in the earth's crust that it says scientists claim is the only way to protect nature's balance.
"We have to make sure that we have the highest safety standards in the world to protect our citizens, our water and the ground against nuclear contamination," said EU energy commissioner Guenther Oettinger, specifying that depths should be "a minimum of 300 metres (990 feet)."
The proposals immediately fell foul of anti-nuclear Greenpeace, whose "dirty energy" campaigner Jan Haverkamp termed them "sub-standard."
"It would take an engineering genius to safely bury white-hot, highly-dangerous nuclear waste deep underground for longer than mankind has been on the planet," he said.
"We fear a disposal facility could rupture high-level nuclear waste into the water table for hundreds of thousands of years."
Quite simply, added leading German Green EU lawmaker Rebecca Harms, the plans "do not address citizens' concerns given the danger posed by radioactive waste."
Oettinger acknowledged that two similar initiatives were previously batted away by states, but insisted this one "will not be blocked" under post-Lisbon treaty majority voting.
The commission is targeting adoption next year, and said states would then have four years to nail down a "concrete timetable" for constructing facilities, including "the financing schemes chosen."
The commission wants nuclear power plant operators "to put money aside for the financing of future disposals."
Producers would not be allowed to export nuclear waste to countries outside the EU for final disposal.
Current schemes offering so-called "interim storage" are given a lifespan of "maximal 50-100 years," the commission said, meaning waste "has to be retrieved and repackaged."
Spent fuel and radioactive waste "need continuous maintenance and oversight," it said.
As the material is typically near the surface, "there is in addition a risk of accidents, including airplane crashes, fires or earthquakes."
Each year, 7,000 cubic metres (247,000 cubic feet) of "high-level" waste that cannot be re-used are produced in the EU, and by 2020, a definitive solution must be found for 1.8 million cubic metres.
Once the rules are adopted, Brussels would be able to fine states that miss targets.
Finland plans to have the sort of repository the commission says science recommends operational in 2020, Sweden in 2023 and France in 2025, Oettinger's office said.
There are 143 nuclear power reactors in use across 14 of the EU's 27 states, with another two, Italy and Poland, planning to build their first.
Not every country would need to host a disposal site, should cross-border public support emerge for sharing.
Most European nations have settled on maintaining nuclear energy at the core of their power needs for coming generations, as oil threatens to run dry and new green technologies have yet to deliver their full potential.
The first nuclear plant to enter service in the EU was Calder Hall, which came on line in northwest England in 1956.
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Monday, September 20, 2010

Processing of Used Nuclear Fuel

Processing of Used Nuclear Fuel

(Updated September 2010) 
  • Used nuclear fuel has long been reprocessed to extract fissile materials for recycling and to reduce the volume of high-level wastes. 
  • New reprocessing technologies are being developed to be deployed in conjunction with fast neutron reactors which will burn all long-lived actinides. 
  • A significant amount of plutonium recovered from used fuel is currently recycled into MOX fuel; a small amount of recovered uranium is recycled. 
A key, nearly unique, characteristic of nuclear energy is that used fuel may be reprocessed to recover fissile and fertile materials in order to provide fresh fuel for existing and future nuclear power plants. Several European countries, Russia and Japan have had a policy to reprocess used nuclear fuel, although government policies in many other countries have not yet addressed the various aspects of reprocessing.
Over the last 50 years the principal reason for reprocessing used fuel has been to recover unused uranium and plutonium in the used fuel elements and thereby close the fuel cycle, gaining some 25% more energy from the original uranium in the process and thus contributing to energy security. A secondary reason is to reduce the volume of material to be disposed of as high-level waste to about one fifth. In addition, the level of radioactivity in the waste from reprocessing is much smaller and after about 100 years falls much more rapidly than in used fuel itself.
In the last decade interest has grown in recovering all long-lived actinides together (i.e. with plutonium) so as to recycle them in fast reactors so that they end up as short-lived fission products. This policy is driven by two factors: reducing the long-term radioactivity in high-level wastes, and reducing the possibility of plutonium being diverted from civil use – thereby increasing proliferation resistance of the fuel cycle. If used fuel is not reprocessed, then in a century or two the built-in radiological protection will have diminished, allowing the plutonium to be recovered for illicit use (though it is unsuitable for weapons due to the non-fissile isotopes present).
Reprocessing used fuela to recover uranium (as reprocessed uranium, or RepU) and plutonium (Pu) avoids the wastage of a valuable resource. Most of it – about 96% – is uranium, of which less than 1% is the fissile U-235 (often 0.4-0.8%); and up to 1% is plutonium. Both can be recycled as fresh fuel, saving up to 30% of the natural uranium otherwise required. The materials potentially available for recycling (but locked up in stored used fuel) could conceivably run the US reactor fleet of about 100 GWe for almost 30 years with no new uranium input.
So far, almost 90,000 tonnes (of 290,000 t discharged) of used fuel from commercial power reactors has been reprocessed. Annual reprocessing capacity is now some 4000 tonnes per year for normal oxide fuels, but not all of it is operational.
Between now and 2030 some 400,000 tonnes of used fuel is expected to be generated worldwide, including 60,000 t in North America and 69,000 t in Europe.
World commercial reprocessing capacity1,2 
(tonnes per year)
LWR fuel France, La Hague
1700
UK, Sellafield (THORP)
900
Russia, Ozersk (Mayak)
400
Japan (Rokkasho)
800
Total (approx)
3800
Other nuclear fuels UK, Sellafield (Magnox)
1500
India
275
Total (approx)
1750
Total civil capacity
5550
Products of reprocessing
The composition of reprocessed uranium (RepU) depends on the initial enrichment and the time the fuel has been in the reactor, but it is mostly U-238. It will normally have less than 1% U-235 (typically about 0.5% U-235) and also smaller amounts of U-232 and U-236 created in the reactor. The U-232, though only in trace amounts, has daughter nuclides which are strong gamma-emitters, making the material difficult to handle. However, once in the reactor, U-232 is no problem (it captures a neutron and becomes fissile U-233). It is largely formed through alpha decay of Pu-236, and the concentration of it peaks after about 10 years of storage.
The U-236 isotope is a neutron absorber present in much larger amounts, typically 0.4% to 0.6% – more with higher burn-up – which means that if reprocessed uranium is used for fresh fuel in a conventional reactor it must be enriched significantly more (e.g. up to one-tenth more) than is required for natural uraniumb. Thus RepU from low burn-up fuel is more likely to be suitable for re-enrichment, while that from high burn-up fuel is best used for blending or MOX fuel fabrication.
The other minor uranium isotopes are U-233 (fissile), U-234 (from original ore, enriched with U-235, fertile), and U-237 (short half-life beta emitter). None of these affects the use of handling of the reprocessed uranium significantly. In the future, laser enrichment techniques may be able to remove these isotopes.
Reprocessed uranium (especially from earlier military reprocessing) may also be contaminated with traces of fission products and transuranics. This will affect its suitability for recycling either as blend material or via enrichment. Over 2002-06 USEC successfully cleaned up 7400 tonnes of technetium-contaminated uranium from the US Department of Energy.
Most of the separated uranium (RepU) remains in storage, though its conversion and re-enrichment (in UK, Russia and Netherlands) has been demonstrated, along with its re-use in fresh fuel. Some 16,000 tonnes of RepU from Magnox reactors in UK has been usedc to make about 1650 tonnes of enriched AGR fuel. In Belgium, France, Germany and Switzerland over 8000 tonnes of RepU has been recycled into nuclear power plants. In Japan the figure is over 335 tonnes in tests and in India about 250 t of RepU has been recycled into PHWRs. Allowing for impurities affecting both its treatment and use, RepU value has been assessed as about half that of natural uranium.
Plutonium from reprocessing will have an isotopic concentration determined by the fuel burn-up level. The higher the burn-up levels, the less value is the plutonium, due to increasing proportion of non-fissile isotopes and minor actinides, and depletion of fissile plutonium isotopesd. Whether this plutonium is separated on its own or with other actinides is a major policy issue relevant to reprocessing (see section on Reprocessing policies below).
Most of the separated plutonium is used almost immediately in mixed oxide (MOX) fuel. World MOX production capacity is currently around 200 tonnes per year, nearly all of which is in France (see page on Mixed Oxide (MOX) Fuel).
Inventory of separated recyclable materials worldwide3 
Quantity (tonnes) Natural U equivalent (tonnes)
Plutonium from reprocessed fuel 320 60,000
Uranium from reprocessed fuel 45,000 50,000
Ex-military plutonium 70 15,000
Ex-military high-enriched uranium 230 70,000
More at link
http://www.world-nuclear.org/info/inf69.html

 

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