High level waste
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2008-02-25T03:00:51Z
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'''High level waste''' (HLW) is a type of [[nuclear waste]] that arises from the use of uranium fuel in a [[nuclear reactor]] and [[nuclear weapon]]s processing. It contains the [[fission products]] and [[transuranic]] elements generated in the [[Nuclear reactor core|reactor core]]. HLW accounts for over 95% of the total radioactivity produced in the process of nuclear electricity generation.
High level waste is very radioactive and, therefore, requires special shielding during handling and transport. It also needs cooling, because it generates a great deal of heat.
A typical large nuclear reactor produces 25-30 tons of [[spent nuclear fuel |spent fuel]] per year. If the fuel were [[nuclear reprocessing|reprocessed]] and [[vitrification|vitrified]], the waste would be only about three cubic meters per year.
It is generally accepted that the final waste will be disposed of in a [[deep geological repository]], and many countries have developed plans for such a site, including [[France]], [[Japan]], and the [[United States]].
==Definitions==
High level waste is defined as:
''Spent (used) reactor fuel''.
* [[Spent nuclear fuel]] is used fuel from a reactor that is no longer efficient in creating electricity, because its fission process has slowed due to a build-up of [[Nuclear poison|reaction poisons]]. However, it is still [[Decay heat|thermally]] hot, highly [[radioactive]], and potentially harmful.
''Waste materials from reprocessing''.
*Materials for [[nuclear weapon]]s are acquired by [[Nuclear reprocessing|reprocessing]] spent nuclear fuel from breeder reactors. Reprocessing is a method of chemically treating spent fuel to separate out uranium and plutonium. The byproduct of reprocessing is a highly radioactive [[sludge]] residue.
== Disposing of high-level wastes ==
High-level radioactive waste is stored temporarily in [[spent fuel pool]]s and in [[dry cask storage]] facilities.
In 1997, in the 20 countries which account for most of the world's nuclear power generation, spent fuel storage capacity at the reactors was 148,000 tonnes, with 59% of this utilized. Away-from-reactor storage capacity was 78,000 tonnes, with 44% utilised. With annual additions of about 12,000 tonnes, issues for final disposal are not urgent.
==External links==
*[http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/radwaste.html NRC Backgrounder on Radioactive Waste]
==See also==
*[[Radioactive waste]]
*[[low level waste]]
*[[transuranic waste]]
*[[spent nuclear fuel]]
*[[Mixed waste (radioactive/hazardous)|mixed waste]]
==References==
Fentiman, Audeen W. and James H. Saling. ''Radioactive Waste Management''. New York: Taylor & Francis, 2002. Second ed.
Large, John H ''Risks and Hazards arising the Transportation of Irradiated Fuel and Nuclear Materials in the United Kingdom'' R3144-A1, March 2006 [http://www.largeassociates.com/3144%20Spent%20Fuel/R3144-A2%20FINAL.pdf]
[[Category:Waste]]
[[Category:Radioactive waste]]