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| The ''']''', ({{lang-uk|Чорнобильська катастрофа}}) ''Chornobylʹsʹka katastrofa,'' was a ] that occurred on 26 April 1986 at the ] in the ] (then part of the ]), now in ]. | |||
| ] ] as seen from inside the town's ].]] | |||
| Following the accident, questions arose about the future of the plant and its eventual fate. All work on the unfinished reactors 5 and 6 was halted three years later. However, the trouble at the Chernobyl plant did not end with the disaster in ] 4. The damaged reactor was sealed off and {{convert|200|m3|yd3|-1|sp=us}} of ] was placed between the disaster site and the operational buildings.{{Citation needed|date=March 2011}} The Ukrainian government continued to let the three remaining reactors operate because of an ] shortage in the country. | |||
| In 1991, a fire broke out in the turbine building of reactor 2;<ref></ref> the authorities subsequently declared the reactor damaged beyond repair and had it taken offline. Reactor 1 was decommissioned in November 1996 as part of a deal between the Ukrainian government and international organizations such as the IAEA to end operations at the plant. On 15 December 2000, then-President ] personally turned off Reactor 3 in an official ceremony, shutting down the entire site.<ref> polled in May 2008 reports shut down for units 1, 2, 3 and 4 respectively at 1996/11/30, 1991/10/11, 2000/12/15 and 1986/04/26.</ref> | |||
| == Chernobyl today == | |||
| {{Merge to |Chernobyl Nuclear Power Plant|discuss=Talk:Chernobyl after the disaster#Proposed mergers (and subsequent deletion of this page) |date=April 2012}} | |||
| === Containment of the reactor === | |||
| The Chernobyl reactor is now enclosed in a large concrete ], which was built quickly to allow continuing operation of the other reactors at the plant.<ref></ref> | |||
| A ] was to have been built by the end of 2005; however, it has suffered ongoing delays and {{as of|2010|lc=y}}, when construction finally began, is expected to be completed in 2013. The structure is being built adjacent to the existing shelter and will be slid into place on rails. It is to be a metal arch {{convert|105|m}} high and spanning {{convert|257|m}}, to cover both unit 4 and the hastily built 1986 structure. The ], set up in 1997, has received ]810 million from international donors and projects to cover this project and previous work. It and the Nuclear Safety Account, also applied to Chernobyl decommissioning, are managed by the ] (EBRD).{{Citation needed|date=August 2008}} | |||
| A handful of Ukrainian scientists work inside the sarcophagus, but outsiders are rarely granted access. In 2006 an ] team led by reporter Richard Carleton and producer Stephen Rice were allowed to enter the sarcophagus for 15 minutes and film inside the control room.<ref>{{cite web|url=http://video.au.msn.com/watch/video/return-to-chernobyl/xf09iii|title=Inside Chernobyl|publisher=60 Minutes Australia, Nine Network Australia|date=16 April 2006}}</ref> | |||
| === Radioactive materials and waste management === | |||
| {{As of|2006}}, some fuel remained in the reactors at units 1 through 3, most of it in each unit's ], as well as some material in a small spent fuel interim storage facility pond (ISF-1). | |||
| In 1999 a contract was signed for construction of a ] management facility to store 25,000 used fuel assemblies from units 1–3 and other operational wastes, as well as material from decommissioning units 1–3 (which will be the first RBMK units decommissioned anywhere). The contract included a processing facility able to cut the RBMK fuel assemblies and to put the material in canisters, which were to be filled with ] and ] shut. | |||
| The canisters were to be transported to ], where the fuel containers would be enclosed for up to 100 years. This facility, treating 2500 fuel assemblies per year, would be the first of its kind for RBMK fuel. However, after a significant part of the storage structures had been built, technical deficiencies in the concept emerged, and the contract was terminated in 2007. The interim spent fuel storage facility (ISF-2) will now be completed by others by mid-2013.{{Citation needed|date=August 2008}} | |||
| Another contract has been let for a liquid radioactive waste treatment plant, to handle some 35,000 cubic meters of low- and intermediate-level liquid wastes at the site. This will need to be solidified and eventually buried along with solid wastes on site.{{Citation needed|date=August 2008}} | |||
| In January 2008, the Ukrainian government announced a 4-stage decommissioning plan that incorporates the above waste activities and progresses towards a cleared site | |||
| .<ref name="WNA-Chernobyl">{{Cite web|url= http://world-nuclear.org/info/chernobyl/inf07.html|title=Chernobyl Accident|date=May 2008|work=]|accessdate=18 June 2008}}</ref> | |||
| === Lava-like fuel-containing materials (FCMs) === | |||
| {{Main|corium (nuclear reactor)}} | |||
| ] | |||
| According to official estimates, about 95% of the fuel in the reactor at the time of the accident (about 180 ]s) remains inside the shelter, with a total radioactivity of nearly 18 million ]s (670 ]). The radioactive material consists of ] fragments, ], and ]-like "]s" (FCM, also called "corium") that flowed through the wrecked reactor building before hardening into a ] form. | |||
| Three different lavas are present in the basement of the reactor building: black, brown, and a ] ceramic. They are ]es with ]s of other materials within them. The porous lava is brown lava that dropped into water and thus cooled rapidly. | |||
| === Degradation of the lava === | |||
| It is unclear how long the ceramic form will retard the release of radioactivity. From 1997 to 2002 a series of papers were published that suggested that the self-irradiation of the lava would convert all 1,200 metric tons into a submicrometer and mobile powder within a few weeks.<ref>V. Baryakhtar, V. Gonchar, A. Zhidkov and V. Zhidkov, Radiation damages and self-spluttering of high radioactive dielectrics: Spontaneous emission of submicrometre dust particles, ''Condensed Matter Physics'', 2002, '''5'''(3{31}), 449–471.</ref> But it has been reported that the degradation of the lava is likely to be a slow and gradual process rather than sudden and rapid.<ref name="Borovoi2006">{{cite journal | last = Borovoi|first=A. A.|year=2006|title=Nuclear fuel in the shelter|journal=Atomic Energy|volume=100|issue=4|pages=249–256|doi=10.1007/s10512-006-0079-3}}</ref> The same paper states that the loss of ] from the wrecked reactor is only {{convert|10|kg|lb|abbr=on}} per year. This low rate of uranium ] suggests that the lava is resisting its environment. The paper also states that when the shelter is improved, the leaching rate of the lava will decrease. | |||
| Some of the surfaces of the lava flows have started to show new uranium ]s such as {{chem|Na|4|(UO|2|)(CO|3|)|3}} and ]. However, the level of radioactivity is such that during one hundred years the self irradiation of the lava {{nowrap|(2 × 10<sup>16</sup>}} α decays per gram and 2 to {{nowrap|5 × 10<sup>5</sup> Gy}} of β or γ) will fall short of the level of self irradiation required to greatly change the properties of ] (10<sup>18</sup> α decays per gram and 10<sup>8</sup> to 10<sup>9</sup> Gy of β or γ). Also the rate of dissolution of the lava in water is very low (10<sup>−7</sup> g-cm<sup>−2</sup> day<sup>−1</sup>), suggesting that the lava is unlikely to dissolve in water.<ref name="Borovoi2006" /> | |||
| === Biological phenomena === | |||
| Scientists studying the seeds harvested from ] and ] plants grown inside (five kilometers from the power plant) the ] found them to be relatively unaffected by radiation. Martin Hajduch from the Institute of Plant Genetics and Biotechnology at the ] said: "We detected very low radioactivity in the seeds. In the stem or leaves there is radioactivity, but it is somehow blocked and doesn't come to the seeds." | |||
| Hajduch and his colleagues in ] conducted a ] study of the plants and found that the seeds harvested inside the ] compared favorably with ones grown in non-contaminated soil outside. | |||
| == Possible further collapse of the sarcophagus == | |||
| {{Merge to |Chernobyl Nuclear Power Plant sarcophagus|discuss=Talk:Chernobyl after the disaster#Proposed mergers (and subsequent deletion of this page) |date=April 2012}} | |||
| ], the concrete block surrounding reactor #4.]] | |||
| The protective box that was placed over the wrecked reactor was named ''object "Shelter"'' by the Soviet government, but the media and the public know it as the "]." | |||
| The present shelter is constructed over the ruins of the reactor building. The two "Mammoth Beams" that support the roof of the shelter rest partly on the structurally unsound west wall of the reactor building that was damaged by the accident.<ref>See </ref> The western end of the shelter roof is supported by a wall at a point designated axis 50. This wall is ], and was cracked by the accident. In December 2006 the "Designed Stabilisation Steel Structure" (DSSS) was extended until 50% of the roof load (about 400 tons) was transferred from the axis 50 wall to the DSSS. {{Citation needed|date=May 2009}} | |||
| The DSSS is a yellow steel object that has been placed next to the wrecked reactor; it is {{convert|63|m|ft|0|sp=us|adj=on}} tall and has a series of ]s that extend through the western ] wall, and is intended to stabilize the sarcophagus.<ref>Nuclear Engineering International, July 2007, page 12.</ref> This was done because if the wall of the reactor building or the roof of the shelter were to collapse, then large amounts of radioactive dust and particles would be released directly into the ], resulting in a large new release of ] into the environment. | |||
| A further threat to the shelter is the concrete slab that formed the "Upper ]" (UBS), situated above the reactor prior to the accident. {{Citation needed|date=May 2009}} This concrete slab was thrown upwards by the ] in the ] and now rests at approximately 15° from vertical. The position of the upper bioshield is considered inherently unsafe, as only debris supports it in its nearly upright position. A collapse of the bioshield would further exacerbate the dust conditions in the shelter, possibly spreading some quantity of radioactive materials out of the shelter, and could damage the shelter itself. The UBS is a circle 15 meters in diameter, weighing 1000 tons and consisting of 2000 cubes, each located above a fuel channel. The shield, called ''Pyatachok'' ("five ] coin") before the disaster, was afterwards named Component "E" and nicknamed "Elena"; the twisted fuel bundles still attached to it are called "Elena's hair."<ref>{{cite web|url=http://www.angelfire.com/extreme4/kiddofspeed/journal/glossary.html|title=Chernobyl Glossary|publisher=Angelfire.com|date= |accessdate=2010-03-22}}</ref><ref>{{cite book|url=http://books.google.com/?id=g-D869NdXYwC&pg=PA50&dq=corium+silicate&cd=16#v=onepage&q=corium%20silicate&f=false|title=Decade of disaster - Google Books|publisher=Books.google.com |date= |accessdate=2010-03-22|isbn=9780252068201|year=2000}}</ref><ref>{{cite web|url=http://www.epa.gov/rpdweb00/rert/chernobyltour/blast_02.html|title=Chernobyl Tour | Radiation Protection | US EPA|publisher=Epa.gov|date=2006-06-28|accessdate=2010-03-22}}</ref> | |||
| == Wildlife status == | |||
| {{see also|Radiation hormesis}} | |||
| {{Merge to |Chernobyl Exclusion Zone|discuss=Talk:Chernobyl after the disaster#Proposed mergers (and subsequent deletion of this page) |date=April 2012}} | |||
| The Exclusion Zone around the Chernobyl nuclear power station is reportedly a haven for ].<ref name="wildlife">'']'', 20 April 2006, </ref><ref name="Mycio">{{Cite book|publisher = Joseph Henry Press|isbn=0309094305|last=Mycio|first=Mary|title=Wormwood Forest: A Natural History of Chernobyl|date=2005-09-09|accessdate=2009-09-25|url=http://books.google.com/?id=pJ7X3Vft5BQC&printsec=frontcover&dq=Wormwood+Forest:+A+Natural+History+of+Chernobyl#v=onepage&q=&f=false}}</ref> As humans were evacuated from the area 25 years ago, existing animal populations multiplied and rare species not seen for centuries have returned or have been reintroduced, for example ], ], ], ], ], ], and ].<ref name="wildlife"/><ref name="Mycio"/> Birds even nest inside the cracked concrete sarcophagus shielding in the shattered remains of Reactor 4.<ref name="haven"/> The Exclusion Zone is so lush with wildlife and greenery that in 2007 the Ukrainian government designated it a ],<ref name="sanctuary">Mother Nature Network, 7 May 2009, </ref><ref name="baker">{{cite web | |||
| |title=The Chernobyl Nuclear Disaster And Subsequent Creation of a Wildlife Preserve|publisher=''Environmental Toxicology and Chemistry'', Vol.19, No.5, pp.1231-1232, 2000 | |||
| |url=http://www.nsrl.ttu.edu/chornobyl/wildlifepreserve.htm | |||
| |author=Baker, Robert J. and Chesser, Roland K|accessdate=2010-08-14}}</ref> and at 488.7 km<sup>2</sup> it is one of the largest wildlife sanctuaries in Europe.<ref name="Mycio"/> | |||
| According to a 2005 U.N. report, wildlife has returned despite radiation levels that are presently 10 to 100 times higher than normal ]. Although they were significantly higher soon after the accident, the levels have fallen because of ].<ref name="haven">'']'', 7 June 2007, </ref> | |||
| Biologist Anders Møller from the ] in France has been examining the effects of radiation on animals around ] for two decades. | |||
| "Areas with higher radiation have fewer animals, survival and reproduction is reduced, sperm are abnormal and have reduced swimming ability. Abnormalities are commonplace and mutations rates are much elevated," Møller said. | |||
| Last year{{When|date=May 2011}}, Møller and Tim Mousseau published the results of the largest census of animal life in the Chernobyl Exclusion Zone . It revealed, contrary to the Chernobyl Forum's 2005 report, that biodiversity in insects, birds and mammals is declining. | |||
| Not all species are affected by radiation in the same way according to Møller. Some birds -- including migrant species and long distance dispersers -- are more vulnerable to radiation than others, he said. | |||
| Martin Hajduch said animal numbers in the exclusion zone are probably higher now than before the accident. But that's because there are no humans there hunting or fishing.{{fact|date=September 2011}} | |||
| "But if you look at how many species of animals are in the area, I think it would be less," Hajduch said. | |||
| Some researchers say that by halting the destruction of ], the Chernobyl disaster helped wildlife flourish. Biologist Robert J. Baker of ] was one of the first to report that Chernobyl had become a wildlife haven and that many ]s he has studied at Chernobyl since the early 1990s have shown remarkable tolerance for elevated radiation levels.<ref name="haven"/><ref name="baker"/> | |||
| Møller ''et al.'' (2005) suggested that reproductive success and annual survival rates of ] are much lower in the Chernobyl exclusion zone; 28% of barn swallows inhabiting Chernobyl return each year, while at a control area at ] 250 km to the southeast, the return rate is around 40%.<ref name="despite">{{Cite news|issn=0027-9358|last=Ravilious|first=Kate|title=Despite Mutations, Chernobyl Wildlife Is Thriving|work=National Geographic Magazine|accessdate=2009-09-23|date=2009-06-29|url=http://news.nationalgeographic.com/news/2006/04/0426_060426_chernobyl_2.html}}</ref><ref name="Moller1">{{Cite journal|doi=10.1111/j.1365-2656.2005.01009.x|volume=74|issue=6|pages=1102–1111|last=Møller|first=A. P.|coauthors=T. A. Mousseau, G. Milinevsky, A. Peklo, E. Pysanets, T. Szép|title=Condition, reproduction and survival of barn swallows from Chernobyl|journal=Journal of Animal Ecology|year=2005}}</ref> A later study by Møller ''et al.'' (2007) furthermore claimed an elevated frequency of 11 categories of subtle physical abnormalities in barn swallows, such as bent ]s, deformed ]s, deformed ]s, and isolated ] ]s.<ref name="Møller2">{{Cite journal|doi=10.1098/rsbl.2007.0136|volume=3|issue=4|pages=414–417|last=Møller|first= A.P.|coauthors=T.A Mousseau, F de Lope, N Saino|title=Elevated frequency of abnormalities in barn swallows from Chernobyl|journal=Biology Letters|accessdate=2009-09-23|year=2007|url=http://rsbl.royalsocietypublishing.org/content/3/4/414.abstract|pmid=17439847|pmc=1994720}}</ref> | |||
| Smith et al. (2007) have disputed Møller's findings and instead proposed that a lack of human influence in the exclusion zone locally reduced the swallows' ] prey and that radiation levels across the vast majority of the exclusion zone are now too low to have an observable negative effect.<ref name="SmithJT">{{Cite journal|doi=10.1098/rsbl.2007.0430|volume=4|issue=1|pages=63–64|last=Smith|first=J.T.|title=Is Chernobyl radiation really causing negative individual and population-level effects on barn swallows?|journal=Biology Letters|accessdate=2009-09-23|date=2008-02-23|url=http://rsbl.royalsocietypublishing.org/content/4/1/63.full.pdf+html|pmid=18042513|pmc=2412919}}</ref> But the criticisms raised were responded to in Møller ''et al.'' (2008).<ref name="Møller3">{{Cite journal|doi=10.1098/rsbl.2007.0528|volume=4|issue=1|page=65|last=Møller|first=A. P.|coauthors=T. A. Mousseau, F. de Lope, N. Saino|title=Anecdotes and empirical research in Chernobyl|journal=Biology Letters|year=2008}}</ref> It is possible that barn swallows are particularly vulnerable to elevated levels of ] because they are ]; they arrive in the exclusion area exhausted and with depleted reserves of ] ]s after an arduous journey.<ref name="despite"/> | |||
| Several research groups have suggested that ]s in the area have adapted to cope with the high radiation levels, for example by increasing the activity of ] machinery and by ].<ref name="Danchenko1">{{Cite journal|doi=10.1021/pr900034u|volume=8|issue=6|pages=2915–2922|last=Danchenko|first=Maksym|coauthors=Ludovit Skultety, Namik M. Rashydov, Valentyna V. Berezhna, L’ubomír Mátel, Terézia Salaj, Anna Pret’ová, Martin Hajduch|title=Proteomic Analysis of Mature Soybean Seeds from the Chernobyl Area Suggests Plant Adaptation to the Contaminated Environment|journal=Journal of Proteome Research|date=2009-06-05|pmid=19320472}}</ref><ref name="Kovalchuk1">{{Cite journal|doi=10.1104/pp.104.040477|volume=135|issue=1|pages=357–363|last=Kovalchuk|first=Igor|coauthors=Vladimir Abramov, Igor Pogribny, Olga Kovalchuk|title=Molecular Aspects of Plant Adaptation to Life in the Chernobyl Zone|journal=Plant Physiol.|accessdate=2009-09-24|date=2004-05-01|url=http://www.plantphysiol.org/cgi/content/abstract/135/1/357|pmid=15133154|pmc=429389}}</ref><ref name="Kovalchuk1">{{Cite journal|doi=10.1016/S0027-5107(03)00103-9|volume=529|issue=1–2|pages=13–20|last=Kovalchuk|first=Olga|coauthors=Paula Burke, Andrey Arkhipov, Nikolaj Kuchma, S. Jill James, Igor Kovalchuk, Igor Pogribny|title=Genome hypermethylation in Pinus silvestris of Chernobyl—a mechanism for radiation adaptation?|journal=Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis|accessdate=2009-09-24|date=2003-08|url=http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T2C-490RJBG-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1023393770&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=c4eb399cbfe24db6fc457449bf0204bc}}</ref><ref name="Boubriak1">{{Cite journal|doi=10.1093/aob/mcm276|volume=101|issue=2|pages=267–276|last=Boubriak|first=I. I.|coauthors=D. M. Grodzinsky, V. P. Polischuk, V. D. Naumenko, N. P. Gushcha, A. N. Micheev, S. J. McCready, D. J. Osborne|title=Adaptation and Impairment of DNA Repair Function in Pollen of Betula verrucosa and Seeds of Oenothera biennis from Differently Radionuclide-contaminated Sites of Chernobyl|journal=Ann Bot|accessdate=2009-09-24|date=2008-01-01|url=http://aob.oxfordjournals.org/cgi/content/abstract/101/2/267|pmid=17981881|pmc=2711018}}</ref> Given the uncertainties, further research is needed to assess the long-term health effects of elevated ionizing radiation from Chernobyl on flora and fauna.<ref name="haven"/> | |||
| == Grass and forest fires == | |||
| {{Merge to |Chernobyl Exclusion Zone|discuss=Talk:Chernobyl after the disaster#Proposed mergers (and subsequent deletion of this page) |date=April 2012}} | |||
| It is known that ]s can make radioactivity mobile again.<ref name="Dusha-Gudym-1992"/><ref>{{PDFlink|http://www.maik.ru/abstract/radchem/4/radchem0102_abstract.pdf|5.07 KB}}</ref><ref>{{Cite web|url=http://www.fire.uni-freiburg.de/iffn/country/rus/rus_16.htm |title=News from the Forest Fire Situation in the Radioactively Contaminated Regions|first=Eduard P.|last=Davidenko|coauthors=Johann Georg Goldammer|date=January 1994}}</ref><ref>{{cite web|title=Radioactive fires threaten Russia and Europe|url=http://newsfromrussia.com/main/2002/09/18/36851.html|date=2002-09-18|publisher=Pravda.ru|first=Mikhail|last=Antonov|coauthors=Maria Gousseva}}</ref> In particular V.I. Yoschenko ''et al.'' reported on the possibility of increased mobility of ], ], and ] due to ] and ]s.<ref>Yoschenko ''et al.'', ''Journal of Environmental Radioactivity'', 2006, '''86''', 143–163.</ref> As an experiment, fires were set and the levels of the radioactivity in the air downwind of these fires was measured. | |||
| Grass and forest fires have happened inside the contaminated zone, releasing ] into the atmosphere. In 1986 a series of fires destroyed 23.36 km<sup>2</sup> (5,772 acres) of forest, and several other fires have since burned within the {{convert|30|km|mi|0|abbr=on}} zone. A serious fire in early May 1992 affected 5 km<sup>2</sup> (1,240 acres) of land including 2.7 km<sup>2</sup> (670 acres) of forest. This resulted in a great increase in the levels of ] in airborne dust.<ref name="Dusha-Gudym-1992">{{Cite web|url=http://www.fire.uni-freiburg.de/iffn/country/rus/rus_7.htm|title=Forest Fires on the Areas Contaminated by Radionuclides from the Chernobyl Nuclear Power Plant Accident|last=Dusha-Gudym|first=Sergei I.|date=August 1992|work=IFFN|pages=No. 7, p. 4–6|publisher=Global Fire Monitoring Center (GFMC)|accessdate=2008-06-18}}</ref><ref>{{PDFlink||416 KB}}</ref><ref>{{PDFlink||139 KB}}</ref><ref>{{cite web|url=http://www.fao.org/docrep/004/y2795e/y2795e08a.htm|title=Fire prevention in radiation contaminated forests|last=Allard|first= Gillian|publisher=Forestry Department, ]|accessdate=2008-06-18}}</ref> | |||
| In 2010, ] affected contaminated areas, specifically the surroundings of ] and border regions with ] and ].<ref name=dw>{{cite web |url=http://www.dw-world.de/dw/article/0,,5890452,00.html |author=] |title=Russian fires hit Chernobyl-affected areas, threatening recontamination |date=August 11, 2010}}</ref> The Russian government claims that there has been no discernible increase in radiation levels, while ] accuses the government of denial.<ref name=dw/> | |||
| == See also == | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] (Wormwood Forest) | |||
| * ] | |||
| * ] | |||
| * ] (Exclusion Zone) | |||
| == External links == | |||
| * | |||
| ==References== | |||
| {{reflist|2}} | |||
| {{DEFAULTSORT:Chernobyl Disaster}} | |||
| ] | |||
| ] | |||
| ] | |||
| ] | |||
| ] | |||
| ] | |||
| ] | |||
| ] | |||
| ] | |||
| ] | |||
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