Chernobyl disaster: Difference between revisions

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| reported deaths = 2 killed by debris [[Valery Khodemchuk|(including 1 missing)]] and 28 killed by [[acute radiation syndrome|acute radiation sickness]]. <br />15 terminal cases of thyroid cancer, with varying estimates of increased cancer mortality over subsequent decades <br />(for more details, see [[Deaths due to the Chernobyl disaster|Deaths due to the disaster]])

The '''Chernobyl disaster'''{{efn|Sometimes spelled as the '''Chornobyl disaster''' because of the Ukrainian name for Chernobyl. Russian: Авария на Чернобыльской АЭС. Ukrainian: Чорнобильська катастрофа.}} began on 26 April 1986 with the explosion of the No.&nbsp;4 [[nuclear reactor|reactor]] of the [[Chernobyl Nuclear Power Plant]], near the city of [[Pripyat]] in thenorthern northUkraine, ofnear the [[Ukrainian Soviet Socialist Republic|Ukrainian SSR]], close to theBelarus border with the [[Byelorussian SSR]], in the [[Soviet Union]].<ref>{{Cite web |title=Accident of 1986 |url=https://chnpp.gov.ua/en/about/history-of-the-chnpp/accident-of-1986 |access-date=14 July 14, 2022 |website=Chornobyl NPP}}</ref> It is one of only two nuclear energy accidents rated at seven—thethe maximum severity—onseverity on the [[International Nuclear Event Scale]], the other being the 2011 [[Fukushima nuclear disaster]] in [[Japanaccident]]. The initial emergency response and subsequent mitigation efforts involved more than [[Chernobyl liquidators|500,000 personnel]] and cost an estimated 18{{nbsp}}billion [[Soviet roubleruble|roublerubles]]s—roughly US(about $68{{nbsp}}billion USD in 2019, adjusted for inflation).<ref name="OECD02-Ch2">{{cite web |year=2002 |title=Chernobyl: Assessment of Radiological and Health Impact, 2002 update; Chapter II – The release, dispersion and deposition of radionuclides |url=https://www.oecd-nea.org/rp/reports/2003/nea3508-chernobyl.pdf |url-status=live |archive-url=https://web.archive.org/web/20150622010856/https://www.oecd-nea.org/rp/reports/2003/nea3508-chernobyl.pdf |archive-date=22 June 2015 |access-date=3 June 2015 |publisher=OECD-NEA}}</ref> It remains the worst nuclear disaster in history,<ref>{{Cite web |title=The Chornobyl Accident |url=https://www.unscear.org/unscear/en/areas-of-work/chernobyl.html |access-date=19 September 2023 |website=[[United Nations Scientific Committee on the Effects of Atomic Radiation]] |language=en}}</ref><ref>{{Cite journal |last1=Steinhauser |first1=Georg |last2=Brandl |first2=Alexander |last3=Johnson |first3=Thomas E. |date=2014 |title=Comparison of the Chernobyl and Fukushima nuclear accidents: A review of the environmental impacts |url=https://linkinghub.elsevier.com/retrieve/pii/S004896971301173X |journal=Science of the Total Environment |language=en |volume=470-471 |pages=800–817 |doi=10.1016/j.scitotenv.2013.10.029|pmid=24189103 }}</ref> and the [[List of disasters by cost|costliest disaster in human history]], with an estimated cost of

The accidentdisaster occurred duringwhile running a test ofto thesimulate steamcooling turbine'sthe abilityreactor toduring poweran the emergency feedwater pumpsaccident in theblackout eventconditions. ofThe aoperators simultaneouscarried lossout ofthe external power and coolant pipe rupture.test Followingdespite an accidental drop in reactor power to near-zero, theand operatorsdue restarted the reactor in preparation for the turbine test withto a prohibiteddesign control rod configuration. Upon successful completion of the testissue, theattempting reactor was thento shut down forthe maintenance.reactor Duein tothose a variety of factors, this actionconditions resulted in a dramatic power surge. at the base of theThe reactor whichcomponents broughtruptured, aboutlost the rupture of reactor componentscoolants, and the loss of coolant. This process led toresulting steam explosions and a [[Nuclear meltdown|meltdown]], which destroyed the containment building. This was, followed by a reactor core fire whichthat lastedspread until 4 May 1986, during which airborne [[radioactive contamination|radioactive contaminants]] were spread throughoutacross the [[Soviet Union|USSR]] and Europe.<ref>{{Cite journal|last=McCall|first=Chris|date=April 2016|title=Chernobyl disaster 30 years on: lessons not learned|journal=The Lancet|volume=387|issue=10029|pages=1707–1708|doi=10.1016/s0140-6736(16)30304-x|pmid=27116266|s2cid=39494685|issn=0140-6736}}</ref><ref>{{cite book|chapter=Chernobyl-Born Radionuclides in Geological Environment|date=2014|pages=25–38|publisher=John Wiley & Sons, Inc|isbn=978-1-118-96222-0|doi=10.1002/9781118962220.ch2|title=Groundwater Vulnerability|series=Special Publications}}</ref> In response to the initial accident, aA {{convert|10|km|mi|adj=on}} radius [[Chernobyl Exclusion Zone|exclusion zone]] was createdestablished 36 hours after the accident, frominitially whichevacuating approximatelyaround 49,000 people were evacuated, primarily from [[Pripyat]]. The exclusion zone was later increasedexpanded to a radius of {{convert|30|km}}, fromresulting whichin anthe additionalevacuation of approximately ~68,000 peoplemore were evacuatedpeople.<ref name="Nuclear Disasters pp 55">{{cite book |title=Nuclear Disasters & The Built Environment: A Report to the Royal Institute |last1=Steadman |first1=Philip |last2=Hodgkinson |first2=Simon |date=1990 |publisher=Butterworth Architecture |isbn=978-0-40850-061-6 |page=55}}</ref>

Following the reactor explosion, which killed two engineers and severely burned two moreothers, an emergency operation began to put out the fires and stabilize the surviving reactor. began,Of during whichthe 237 workers were hospitalized, of which 134 exhibitedshowed symptoms of [[acute radiation syndrome]] (ARS).; Among28 thoseof hospitalized, 28them died within the following three months, all of whom were hospitalized for ARS. InOver the followingnext 10 yearsdecade, 14 more workers (9nine whoof whom had been hospitalized with ARS) died of various causes mostly unrelated to radiation exposure.<ref name=":5">{{Cite journal |last1=Wagemaker |first1=G. |last2=Guskova |first2=A. K. |last3=Bebeshko |first3=V. G. |last4=Griffiths |first4=N. M. |last5=Krishenko |first5=N. A. |date=1996 |title=Clinically Observed Effects in Individuals Exposed to Radiation as a Result of the Chernobyl Accident |journal=One Decade After Chernobyl: Summing up the Consequences of the Accident, Proceedings of an International Conference, Vienna. |pages=173–198}}</ref> 15It childhoodis [[thyroidthe cancer]]only deathsinstance werein attributedcommercial tonuclear thepower disasterhistory {{aswhere radiation-related of|2011|lc=y}}fatalities occurred.<ref name="WHO2012">{{citeCite webbook |urllast1=https://www.who.int/ionizing_radiation/chernobyl/20110423_FAQs_Chernobyl.pdfZohuri |first1=Bahman |title=ChernobylThermodynamics 25thin anniversaryNuclear –Power FrequentlyPlant AskedSystems Questions|last2=McDaniel |datefirst2=23Patrick April|publisher=[[Springer 2011Science+Business Media|websiteSpringer]] |year=World2019 Health|isbn=978-3-319-93918-6 Organization|edition=2nd |access-datepage=14597 April|language=en}}</ref><ref>{{Cite 2012web |archivedate=2024-04-26 |title=Chernobyl Accident 1986 – World Nuclear Association |url=https://web.archiveworld-nuclear.org/webinformation-library/20120417011209safety-and-security/http://www.who.int/ionizing_radiationsafety-of-plants/chernobyl/20110423_FAQs_Chernobyl.pdf-accident |archiveaccess-date=17 April 20122024-05-09 |url-statuswebsite=live world-nuclear.org}}</ref> As of 2011, 15 childhood [[thyroid cancer]] deaths were attributed to the disaster.<ref name="who.intWHO2012">{{cite web |url=https://www.who.int/mediacentreionizing_radiation/news/releases/2005/pr38/enchernobyl/20110423_FAQs_Chernobyl.pdf |title=Chernobyl: the25th trueanniversary scale– ofFrequently theAsked accidentQuestions |date=523 SeptemberApril 20052011 |website=World Health Organization |access-date=814 NovemberApril 20182012 |archive-url=https://web.archive.org/web/2018022509582820120417011209/http://www.who.int/mediacentreionizing_radiation/news/releases/2005/pr38/enchernobyl/20110423_FAQs_Chernobyl.pdf |archive-date=2517 FebruaryApril 20182012 |url-status=live }}</ref> AThe [[United Nations Scientific Committee on the Effects of Atomic Radiation|United Nations committee]] found that to dateestimates fewer than 100 deaths have resulted from the fallout.<ref>{{cite web |title=UNSCEAR assessments of the Chernobyl accident |url=http://www.unscear.org/unscear/en/chernobyl.html |website=www.unscear.org |access-date=13 September 2007 |archive-date=13 May 2011 |archive-url=https://web.archive.org/web/20110513235907/http://www.unscear.org/unscear/en/chernobyl.html |url-status=live }}</ref> Model predictionsPredictions of the eventual total death toll in the coming decades vary.; Thea most widely cited study conducted by the2006 World Health Organization in 2006study predictedprojected 9,000 cancer-related fatalities in [[Ukraine]], Belarus, and [[Russia]].<ref name="World Health Organization report ex">{{cite web |url=https://www.who.int/mediacentre/news/releases/2006/pr20/en/index.html |title=World Health Organization report explains the health impacts of the world's worst-ever civil nuclear accident |date=26 April 2006 |website=World Health Organization |access-date=4 April 2011 |archive-url=https://web.archive.org/web/20110404181327/http://www.who.int/mediacentre/news/releases/2006/pr20/en/index.html |archive-date=4 April 2011 |url-status=dead }}</ref>

Following the disaster, Pripyat was abandoned and eventually replaced by the new purpose-built city of [[Slavutych]]. The [[Chernobyl Nuclear Power Plant sarcophagus]], wascompleted built byin December 1986. It, reduced the spread of [[radioactive contamination]] from the wreckage and protected it from weathering. The confinement shelter also provided [[radiological protection]] for the crews of the undamaged reactors at the site, which were restarted in late 1986 and 1987. However,In this containment structure was only intended to last for 30 years2016&ndash;2018, and required considerable reinforcement in the early 2000s. The Shelter was heavily supplemented in 2017 by the [[Chernobyl New Safe Confinement]], which was constructed around the old structure. This larger enclosure aimssarcophagus to enable the removal of both the sarcophagus and the reactor debris, whilewith containing the radioactive materials inside. Cleanclean-up is scheduled for completion by 2065.<ref>{{cite news|url=http://www.kyivpost.com/news/nation/detail/56391/|title=Chernobyl nuclear power plant site to be cleared by 2065|newspaper=Kyiv Post|date=3 January 2010|archive-url=https://web.archive.org/web/20121005150746/http://www.kyivpost.com/content/ukraine/chornobyl-nuclear-power-plant-site-to-be-cleared-b-56391.html|archive-date=5 October 2012 }}</ref>

== BackgroundAccident sequence ==

=== Background ===

==== Reactor cooling after shutdown ====

==== Test delay and shift change ====

[[File:RBMK en.svg|thumb|upright=12.52|Process flow diagram of the reactor]]

[[File:Gen II nuclear reactor vessels sizes.svg|thumb|upright=2|Comparative [[Generation II reactor]] vessels size comparison, a design classification of commercial reactors built until the end of the 1990s.]]

The test was to be conducted during the day-shift of 25 April 1986 as part of a scheduled reactor shut downshutdown. The day shift crew had been instructed in advance on the reactor operating conditions to run the test, and, in addition, a special team of [[electrical engineer]]s was present to conduct the one-minuteelectrical test of the new voltage regulating system once the correct conditions had beenwere reached.<ref>{{Harvard citation no brackets|Dyatlov|2003|p=30}}.</ref> As planned, a gradual reduction in the output of the power unit began at 01:06 on 25 April, and the power level had reached 50% of its nominal 3,200&nbsp;MW thermal level by the beginning of the day shift.<ref name=insag7/>{{rp|53}}

The day shift performed many unrelated maintenance tasks, and was scheduled to perform the test at 14:15.<ref name="Karpan44">{{cite book |last1=Karpan |first1=N. V. |title=Chernobyl. Vengeance of the peaceful atom (in Russian) |date=2006 |publisher=IKK "Balance Club" |location=Dnepropetrovsk |isbn=978-966-8135-21-7 |url=http://www.physiciansofchernobyl.org.ua/rus/books/Karpan.html |chapter=Who exploded the Chernobyl NPP, Chronology of events before the accident |chapter-url=http://www.physiciansofchernobyl.org.ua/rus/books/Karpan/44.pdf |access-date=16 August 2009 |archive-date=1 April 2020 |archive-url=https://web.archive.org/web/20200401174807/http://www.physiciansofchernobyl.org.ua/rus/books/Karpan.html |url-status=dead }}</ref>{{rp|3}} Preparations for the test were carried out, including the disabling of the [[emergency core cooling system]].<ref name=insag7/>{{rp|53}} Meanwhile, another regional power station unexpectedly went offline. At 14:00,<ref name=insag7/>{{rp|53}} the [[Kyiv|Kiev]] electrical grid controller requested that the further reduction of Chernobyl's output be postponed, as power was needed to satisfy the peak evening demand, so the test was postponed.

Soon, the day shift was replaced by the evening shift.<ref name="Karpan44"/>{{rp|3}} Despite the delay, the emergency core cooling system was left disabled. This system had to be disconnected via a manual isolating slide valve,<ref name=insag7/>{{rp|51}} which in practice meant that two or three people spent the whole shift manually turning sailboat-helm-sized valve wheels.<ref name="Karpan44"/>{{rp|4}} The system would havehad no influence on the events that unfolded nextdisaster, but allowing the reactor to run for 11 hours outside of the test without emergency protection was indicative of a general lack of safety culture.<ref name=insag7/>{{rp|10,18}}

At 23:04, the Kiev grid controller allowed the reactor shutdown to resume. This delay had some serious consequences: theThe day shift had long since departed, the evening shift was also preparing to leave, and the night shift would not take over until midnight, well into the job. According to plan, the test should have been finished during the day shift, and the night shift would only have had to maintain decay heat cooling systems in an otherwise shut-down plant.<ref name="MedvedevZ"/>{{rp|36–38}}

The night shift had very limited time to prepare for and carry out the experiment. [[Anatoly Dyatlov]], deputy chief-engineer of the [[Chernobyl Nuclear Power Plant]] (ChNPP), was present to supervise and direct the test. He was one of the test's chief authors and he was the highest-ranking individual present. Unit Shift Supervisor [[Aleksandr Akimov]] was in charge of the Unit 4 night shift, and [[Leonid Toptunov]] was the Senior Reactor Control Engineer responsible for the reactor's operational regimen, including the movement of the [[control rod]]s. 25-year-old Toptunov had worked independently as a senior engineer for approximately three months.<ref name="MedvedevZ"/>{{rp|36–38}}

==== Unexpected drop of the reactor power ====

</ref> and an output of 720&nbsp;MW was reached at 00:05 on 26 April.<ref name=insag7/>{{rp|53}} However, due to the reactor's production of a fission byproduct, [[xenon-135]], which is a reaction-inhibiting [[neutron absorber]], power continued to decrease in the absence of further operator action, a process known as [[reactor poisoning]]. In steady-state operation, this is avoided because xenon-135 is "burned off" as quickly as it is created from decaying [[iodine-135]] by the absorption of neutrons from the ongoing chain reaction, becoming highly stable [[xenon-136]]. With the reactor power reduced, high quantities of previously produced [[iodine-135]] were decaying into the neutron-absorbing xenon-135 faster than the reduced [[neutron flux]] could "burn it off".<ref name="nf">{{cite web |url=http://nuclearfissionary.com/2010/03/03/what-happened-at-chernobyl/ |title=What Happened at Chernobyl? |access-date=12 January 2011 |website=Nuclear Fissionary |url-status=dead |archive-url=https://web.archive.org/web/20110714210818/http://nuclearfissionary.com/2010/03/03/what-happened-at-chernobyl/ |archive-date=14 July 2011 }}</ref> Xenon poisoning in this context made reactor control more difficult, but was a predictable and well-understood phenomenon during such a power reduction.

When the reactor power had decreased to approximately 500&nbsp;MW, the reactor power control was switched from LARlocal (Localautomatic Automatic Regulator)regulator to the Automaticautomatic Regulatorsregulators, in order to manually maintain the required power level.<ref name=insag7/>{{rp|11}}<ref name="auto">{{Harvard citation no brackets|Dyatlov|2003|chapter=4}}</ref> AR-1 then activated, removing all four of AR-1's control rods automatically, but AR-2 failed to activate due to an imbalance in its ionization chambers. In response, Toptunov reduced power to stabilize the Automaticautomatic Regulatorsregulators' ionization sensors. The result was a sudden power drop to an unintended near-[[shutdown (nuclear reactor)|shutdown]] state, with a power output of 30&nbsp;MW thermal or less. The exact circumstances that caused the power drop are unknown. Most reports attribute the power drop to Toptunov's error, but Dyatlov reported that it was due to a fault in the AR-2 system.<ref name=insag7/>{{rp|11}}

The reactor was now producing only 5% of the minimum initial power level prescribed for the test.<ref name=insag7/>{{rp|73}} This low reactivity inhibited the burn-off of xenon-135<ref name=insag7/>{{rp|6}} within the [[reactor core]] and hindered the rise of reactor power. To increase power, control-room personnel removed numerous control rods from the reactor.<ref>{{Harvard citation no brackets|Dyatlov|2003|p=31}}</ref> Several minutes elapsed before the reactor was restored to 160 &nbsp;MW at 00:39, at which point most control rods were at their upper limits, but the rod configuration was still within its normal operating limit, with Operational Reactivity Margin (ORM) equivalent to having more than 15 rods inserted. Over the next twenty minutes, reactor power would be increased further to 200&nbsp;MW.<ref name=insag7/>{{rp|73}}

The operation of the reactor at the low power level (and high poisoning level) was accompanied by unstable core temperatures and coolant flow, and, possibly, by instability of [[neutron flux]]. The control room received repeated emergency signals regarding the low levels in one half of the steam/water separator drums, with accompanying drum separator pressure warnings. In response, personnel triggered several rapid influxes of feedwater. [[Relief valve]]s opened to relieve excess steam into a [[Surface condenser|turbine condenser]].{{citation needed|date=April 2022}}

==== Reactor conditions priming the accident ====

When a power level of 200&nbsp;MW was reattained, preparation for the experiment continued, although the power level was much lower than the prescribed 700&nbsp;MW. As part of the test program, two additional main circulating (coolant) pumps were activated at 01:05. The increased coolant flow lowered the overall core temperature and reduced the existing steam voids in the core. Because water absorbs neutrons better than steam, the neutron flux and reactivity decreased. The operators responded by removing more manual control rods to maintain power.<ref name="OECD02-Ch1">{{cite web |url=https://www.oecd-nea.org/rp/reports/2003/nea3508-chernobyl.pdf |title=Chernobyl: Assessment of Radiological and Health Impact, 2002 update; Chapter I – The site and accident sequence |website=OECD-NEA |year=2002 |access-date=3 June 2015 |archive-url=https://web.archive.org/web/20150622010856/https://www.oecd-nea.org/rp/reports/2003/nea3508-chernobyl.pdf |archive-date=22 June 2015 |url-status=live }}</ref><ref>{{cite web |url=http://www.physiciansofchernobyl.org.ua/rus/books/Karpan.html |title=N. V. Karpan |website=Physicians of Chernobyl Association |language=ru |access-date=3 September 2013 |archive-url=https://web.archive.org/web/20120227033355/http://www.physiciansofchernobyl.org.ua/rus/books/Karpan.html |archive-date=27 February 2012 |url-status=live }}</ref> It was around this time that the number of control rods inserted in the reactor fell below the required value of 15. This was not apparent to the operators, because the RBMK did not have any instruments capable of calculating the inserted rod worth in real time.

The combined effect of these various actions was an extremely unstable reactor configuration. Nearly all of the 211 control rods had been extracted manually, and excessively high coolant flow rates throughmeant that the corewater meanthad thatless time to cool between trips through the coolantcore, wastherefore entering the reactor very close to the boiling point. Unlike other [[light-water reactor]] designs, the RBMK design at that time had a positive [[void coefficient]] of reactivity at lowtypical fuel powerburnup levels. This meant that the formation of steam bubbles (voids) from boiling cooling water intensified the nuclear chain reaction owing to voids having lower [[neutron absorption]] than water. UnbeknownstUnknown to the operators, the void coefficient was not counterbalanced by other reactivity effects in the given operating regime, meaning that any increase in boiling would produce more steam voids which further intensified the chain reaction, leading to a [[positive feedback]] loop. Given this characteristic, reactor No.&nbsp;4 was now at risk of a runaway increase in its core power with nothing to restrain it. The reactor was now very sensitive to the regenerative effect of steam voids on reactor power.<ref name=insag7/>{{rp|3,14}}

=== Accident ===

==== Test execution ====

[[File:RBMK Reaktor ChNPP-4.svg|thumb|upright=1.2.6|Plan view of reactor No. 4 core. The number on each control rod indicates the insertion depth in centimeters one minute prior to the disaster. <br />{{Color box|#0067ce|border=darkgray}} neutron detectors (12)<br />{{Color box|#00b150|border=darkgray}} control rods (167)<br />{{Color box|#fed800|border=darkgray}} short control rods from below reactor (32)<br />{{Color box|#de1700|border=darkgray}} automatic control rods (12)<br />{{Color box|#a5b5a4|border=darkgray}} pressure tubes with fuel rods (1661)]]

==== Reactor shutdown and power excursion ====

At 01:23:40, as recorded by the [[SKALA]] centralized control system, a [[scram]] (emergency shutdown) of the reactor was initiated<ref>{{Cite web|url=https://interestingengineering.com/chernobyl-a-timeline-of-the-worst-nuclear-accident-in-history|title=Chernobyl – A Timeline of The Worst Nuclear Accident in History|date=11 May 2019|website=interestingengineering.com|language=en-US|access-date=18 June 2019|archive-date=26 June 2019|archive-url=https://web.archive.org/web/20190626180547/https://interestingengineering.com/chernobyl-a-timeline-of-the-worst-nuclear-accident-in-history|url-status=live}}</ref> as the experiment was wrapping -up.<ref name="auto">{{Harvard citation no brackets|Dyatlov|2003|chapter=4}}.</ref> The scram was started when the AZ-5 button (also known as the EPS-5 button) of the reactor emergency protection system was pressed: this engaged the drive mechanism on all control rods to fully insert them, including the manual control rods that had been withdrawn earlier.

The personnel had already intended to shut down using the AZ-5 button in preparation for scheduled maintenance<ref>{{Harvard citation no brackets|Dyatlov|2003|chapter=1}}.</ref> and the scram likely preceded the sharp increase in power.<ref name=insag7/>{{rp|13}} However, the precise reason why the button was pressed when it was is not certain, as only the deceased Akimov and Toptunov partook inmade that decision, though the atmosphere in the control room was calm, ataccording thatto momenteyewitnesses.<ref>{{cite book |language=ru |chapter-url=http://rrc2.narod.ru/book/gl4.html |first=Anatoly |last=Dyatlov |author-link=Anatoly Dyatlov |title=Chernobyl. How did it happen? |chapter=4 |access-date=5 May 2005 |archive-date=16 May 2006 |archive-url=https://web.archive.org/web/20060516131842/http://rrc2.narod.ru/book/gl4.html |url-status=live }}</ref><ref>{{cite book |last1=Higginbotham |first1=Adam |title=[[Midnight in Chernobyl|Midnight in Chernobyl: the untold story of the world's greatest nuclear disaster]] |year= 2019 |publisher=Simon & Schuster |isbn=978-1-5011-3464-7 |edition=First Simon & Schuster hardcover |ref=higginbotham}}</ref>{{rp|85}} Meanwhile, theThe RBMK designers claim that the button had to have been pressed only after the reactor already began to self-destruct.<ref>{{cite book |languagelast1=ruAdamov |first1=E. O. |last1=Adamov |first2=Yu. M. |last2=Cherkashov |url=http://accidont.ru/book.html |title=Channel Nuclear Power Reactor RBMK |locationlast2=MoscowCherkashov |first2=Yu. M. |publisher=GUP NIKIET |year=2006 |isbn=978-5-98706-018-6 |edition=Hardcover |location=Moscow, Russia |language=ru |display-authors=etal |access-date=14 September 2009 |archive-url=https://web.archive.org/web/20090802042756/http://accidont.ru/book.html |archive-date=2 August 2009 |url-status=live }}</ref>{{rp|578}}

[[File:Chernobyl burning-aerial view of core.jpg|thumb|upright=1.4|Steam plumes continued to be generated days after the initial explosion<ref>{{cite news |url=https://www.theguardian.com/environment/gallery/2011/apr/26/chernobyl-nuclear-disaster-in-pictures |title=Chernobyl nuclear disaster – in pictures |last=Kostin |first=Igor |author-link=Igor Kostin |date=26 April 2011 |newspaper=[[The Guardian]] |access-date=8 November 2018 |archive-url=https://web.archive.org/web/20181108184910/https://www.theguardian.com/environment/gallery/2011/apr/26/chernobyl-nuclear-disaster-in-pictures |archive-date=8 November 2018 |url-status=live }}</ref>]]

A few seconds into the scram, a power spike did occuroccurred, and the core overheated, causing some of the [[fuel rod]]s to fracture. Some have speculated that this also blocked the control rod columns, jamming them at one-third insertion. Within three seconds the reactor output rose above 530&nbsp;MW.<ref name="MedvedevZ"/>{{rp|31}}

Instruments did not register the subsequent course of events; it was reconstructed through mathematical simulation. Per the simulation, theThe power spike would have caused an increase in fuel temperature and steam buildup, leading to a rapid increase in [[Vapor pressure|steam pressure]]. This caused the fuel cladding to fail, releasing the fuel elements into the coolant and rupturing the channels in which these elements were located.<ref>{{cite web |language=ru |url=http://www.reactors.narod.ru/pub/chern_2/chern_2.htm |title=Chernobyl as it was |website=narod.ru |access-date=29 April 2006 |archive-url=https://web.archive.org/web/20060517063327/http://www.reactors.narod.ru/pub/chern_2/chern_2.htm |archive-date=17 May 2006 |url-status=live }}</ref>

==== Steam explosionsExplosions ====

As the [[scram]] continued, the reactor output jumped to around 30,000&nbsp;MW thermal, 10 times its normal operational output, the indicated last reading on the power meter on the control panel. Some estimate the power spike may have gone 10 times higher than that. It was not possible to reconstruct the precise sequence of the processes that led to the destruction of the reactor and the power unit building, but a [[steam explosion]], like the explosion of a [[steam boiler]] from excess vapour pressure, appears to have been the next event. There is a general understanding that it was explosive steam pressure from the damaged fuel channels escaping into the reactor's exterior cooling structure that caused the explosion that destroyed the reactor casing, tearing off and blasting the upper plate called the upper biological shield,<ref name="interestingengineering.com">{{cite web |url=https://interestingengineering.com/chernobyl-a-timeline-of-the-worst-nuclear-accident-in-history |title=Chernobyl – A Timeline of The Worst Nuclear Accident in History |date=11 May 2019 |first=Marcia |last=Wendorf |work=Interesting Engineering |access-date=18 June 2019 |archive-date=26 June 2019 |archive-url=https://web.archive.org/web/20190626180547/https://interestingengineering.com/chernobyl-a-timeline-of-the-worst-nuclear-accident-in-history |url-status=live }}</ref> to which the entire reactor assembly is fastened, through the roof of the reactor building. This is believed to be the first explosion that many heard.<ref>{{cite book |languagelast=ruDavletbaev |first=R. I. |url=http://accidont.ru/Davlet.html |first=R.I. |last=Davletbaev |title=Last shift Chernobyl. Ten years later. Inevitability or chance? |location=Moscow |publisher=Energoatomizdat |year=1995 |isbn=978-5-283-03618-2 |location=Moscow, Russia |language=ru |access-date=30 November 2009 |archive-url=https://web.archive.org/web/20091224094453/http://accidont.ru/Davlet.html |archive-date=24 December 2009 |url-status=live }}</ref>{{rp|366}}

This explosion ruptured further fuel channels, as well as severing most of the coolant lines feeding the reactor chamber,. and asAs a result, the remaining coolant flashed to steam and escaped the reactor core. The total water loss combined with a high positive void coefficient further increased the reactor's thermal power.<ref name=insag7/>

A second, more powerful explosion occurred about two or three seconds after the first; this explosion dispersed the damaged core and effectively terminated the [[nuclear chain reaction]]. This explosion also compromised more of the reactor containment vessel and ejected hot lumps of graphite moderator. The ejected graphite and the demolished channels still in the remains of the reactor vessel caught fire on exposure to air, significantly contributing to the spread of [[radioactive fallout]] and the [[radioactive contamination|contamination]] of outlying areas.<ref name="OECD02-Ch1" />{{efn|Although most reports on the Chernobyl accident refer to a number of graphite fires, it is highly unlikely that the graphite itself burned. According to the [[General Atomics]] website:<ref>{{cite web |url=http://gt-mhr.ga.com/safety.php |title=Graphites |website=General Atomics |access-date=13 October 2016 |url-status=dead |archive-url=https://web.archive.org/web/20120717102758/http://gt-mhr.ga.com/safety.php |archive-date=17 July 2012 }}</ref> "It is often incorrectly assumed that the combustion behavior of graphite is similar to that of charcoal and coal. Numerous tests and calculations have shown that it is virtually impossible to burn high-purity, nuclear-grade graphites." On Chernobyl, the same source states: "Graphite played little or no role in the progression or consequences of the accident. The red glow observed during the Chernobyl accident was the expected color of luminescence for graphite at 700°C and not a large-scale graphite fire, as some have incorrectly assumed." Similarly, nuclear physicist Yevgeny Velikhov,<ref>{{cite web |url=http://news.bbc.co.uk/2/hi/europe/4918742.stm |title=The Chernobyl nightmare revisited |last=Mulvey |first=Stephen |date=18 April 2006 |website=BBC News |access-date=8 November 2018 |archive-url=https://web.archive.org/web/20181108185240/http://news.bbc.co.uk/2/hi/europe/4918742.stm |archive-date=8 November 2018 |url-status=live }}</ref> noted some two weeks after the accident, "Until now the possibility of a catastrophe really did exist: A great quantity of fuel and graphite of the reactor was in an [[incandescent]] state." That is, all the nuclear-[[decay heat]] that was generated inside the uranium fuel (heat that would normally be extracted by back-up coolant pumps, in an undamaged reactor) was instead responsible for making the fuel itself and any graphite in contact with it, glow red-hot. This is contrary to the often-cited interpretation, which is that the graphite was red-hot chiefly because it was chemically [[oxidizing]] with the air.}} The explosion is estimated to have had the [[TNT equivalent|power equivalent]] of 225&nbsp;tons of [[TNT]].<ref name="DeGeerNuclearJet">{{cite journal |doi=10.1080/00295450.2017.1384269 |date=November 2017 |journal=Nuclear Technology |title=A Nuclear Jet at Chernobyl Around 21:23:45 UTC on April 25, 1986 |volume=201 |pages=11–22 |first1=Lars-Erik |last1=De Geer |first2=Christer |last2=Persson |first3=Henning |last3=Rodhe |quote=|url=http://su.diva-portal.org/smash/get/diva2:1168987/FULLTEXT01 |doi-access=free |access-date=20 September 2019 |archive-date=21 July 2018 |archive-url=https://web.archive.org/web/20180721042656/http://su.diva-portal.org/smash/get/diva2:1168987/FULLTEXT01 |url-status=live }}</ref>

After the larger explosion, several employees at the power station went outside to get a clearer view of the extent of the damage. One such survivor, [[Individual involvement in the Chernobyl disaster#Aleksandr Yuvchenko|Alexander Yuvchenko]], recountssaid that once he stepped out and looked up towards the reactor hall, he saw a "very beautiful" laser-like beam of blue light caused by the [[ionized-air glow]] that appeared to be "flooding up into infinity".<ref name="Meyer">{{cite magazine |last1=Meyer |first1=C. M. |date=March 2007 |title=Chernobyl: what happened and why? |magazine=Energize |date=March 2007 |page=41 |url=http://www.eepublishers.co.za/images/upload/Meyer%20Chernobyl%205.pdf |location=Muldersdrift, South Africa |issn=1818-2127 |archive-url=https://web.archive.org/web/20131211073343/http://www.eepublishers.co.za/images/upload/Meyer%20Chernobyl%205.pdf |archive-date=11 December 2013 |magazine=Energize |location=Muldersdrift, South Africa |page=41 |issn=1818-2127}}</ref><ref name="Bond">{{cite magazine |last1=Bond |first1=Michael |title=Cheating Chernobyl |magazine=New Scientist |date=21 August 2004 |volume=183 |issue=2461 |page=46 |url=https://www.newscientist.com/article/mg18324615-300-cheating-chernobyl/ |url-access=subscription |issn=0262-4079 |access-date=5 August 2021 |archive-date=5 August 2021 |archive-url=https://web.archive.org/web/20210805065004/https://www.newscientist.com/article/mg18324615-300-cheating-chernobyl/ |url-status=live }}</ref>

Contrary to safety regulations, [[bitumen]], a combustible material, had been used in the construction of the roof of the reactor building and the turbine hall. Ejected material ignited at least five fires on the roof of the adjacent reactor No.&nbsp;3, which was still operating. It was imperative to put out those fires out and protect the cooling systems of reactor No.&nbsp;3.<ref name="MedvedevZ"/>{{rp|42}} Inside reactor No.&nbsp;3, the chief of the night shift, Yuri Bagdasarov, wanted to shut down the reactor immediately, but chief engineer Nikolai Fomin would not allow this. The operators were given [[respirator]]s and [[potassium iodide]] tablets and told to continue working. At 05:00, Bagdasarov made his own decision to shut down the reactor,<ref name="MedvedevZ"/>{{rp|44}} which was confirmed in writing by Dyatlov and Station Shift Supervisor Rogozhkin.

Anatoli Zakharov, a fireman stationed in Chernobyl since 1980, offered a different description in 2008: "I remember joking to the others, 'There must be an incredible amount of radiation here. We'll be lucky if we're all still alive in the morning.{{'"}}<ref name="nuclruss"/> He also stated, "Of course we knew! If we'd followed regulations, we would never have gone near the reactor. But it was a moral obligation—our duty. We were like [[kamikaze]]."<ref name="nuclruss">{{cite news |last=Higginbotham |first=Adam |lastdate=Higginbotham26 March 2006 |title=Chernobyl 20 years on |url=https://www.theguardian.com/world/2006/mar/26/nuclear.russia |title=Chernobyl 20 years on |newspaper=[[The Observer]] |date=26 March 2006 |accessurl-datestatus=22 March 2010 |location=Londonlive |archive-url=https://web.archive.org/web/20130830011011/http://www.theguardian.com/world/2006/mar/26/nuclear.russia |archive-date=30 August 2013 |urlaccess-statusdate=live22 March 2010 |newspaper=[[The Observer]] |location=London, England}}</ref>

The immediate priority was to extinguish fires on the roof of the station and the area around the building containing Reactor No.&nbsp;4 to protect No.&nbsp;3 and keep its core cooling systems intact. The fires were extinguished by 5:00, but many firefighters received high doses of radiation. The fire inside reactorReactor No.&nbsp;4 continued to burn until 10 May 1986; it is possible that well over half of the graphite burned out.<ref name="MedvedevZ"/>{{rp|73}}

From eyewitness accounts of the firefighters involved before they died (as reported on the [[Canadian Broadcasting Corporation|CBC]] television series ''[[Witness (TV series)|Witness]]''), one described his experience of the radiation as "tasting like metal", and feeling a sensation similar to that of [[paresthesia|pins and needles]] all over his face. This is consistent with the description given by [[Louis Slotin]], a [[Manhattan Project]] physicist who died days after a fatal radiation overdose from [[demon core#Second incident|a criticality accident]].<ref name="zeilig22">{{Cite journal |last=Zeilig |first=Martin |date=August–September 1995 |title=Louis Slotin And 'The Invisible Killer' |journal=The Beaver |volume=75 |issue=4 |pages=20–27 |url=http://www.mphpa.org/classic/FH/LA/Louis_Slotin_1.htm |access-date=28 April 2008 |url-status=dead |archive-url=https://web.archive.org/web/20080516101332/http://www.mphpa.org/classic/FH/LA/Louis_Slotin_1.htm |archive-date=16 May 2008 }}</ref> The explosion and fire threw hot particles of the [[nuclear fuel]] and more dangerous [[fission product]]s into the air. The residents of the surrounding area observed the radioactive cloud on the night of the explosion.

The nearby city of Pripyat was not immediately evacuated. Theand the townspeople, inwere thenot earlyalerted hours ofduring the morning, at 01:23 local time, went about their usual business, completely obliviousnight to what had just happened. However, within a few hours of the explosion, dozens of people fell ill. Later, they reported severe headaches and metallic tastes in their mouths, along with uncontrollable fits of coughing and vomiting.<ref name=TimeDisaster>{{cite book |title=Disasters that Shook the World |publisher=Time Home Entertainment |location=New York |year=2012 |isbn=978-1-60320-247-3}}</ref>{{better source needed|date=October 2018}} As the plant was run by authorities in Moscow, the government of Ukraine did not receive prompt information on the accident.<ref name="shevchenko">{{cite web |url=http://www.istpravda.com.ua/articles/2011/04/25/36971/ |script-title=uk:Валентина Шевченко: 'Провести демонстрацію 1 травня 1986–го наказали з Москви' |website=[[Ukrayinska Pravda|Istorychna Pravda]] |language=uk |date=25 April 2011 |access-date=20 August 2011 |url-status=dead |archive-url=https://web.archive.org/web/20160426221138/http://www.istpravda.com.ua/articles/2011/04/25/36971/ |archive-date=26 April 2016}}</ref>

[[Valentyna Shevchenko (politician)|Valentyna Shevchenko]], then Chairwoman of the Presidium of [[Verkhovna Rada]] of the Ukrainian SSR, recallssaid that Ukraine's acting Minister of Internal Affairs [[Vasyl Durdynets]] phoned her at work at 09:00 to report current affairs; only at the end of the conversation did he add that there had been a fire at the Chernobyl nuclear power plant, but it was extinguished and everything was fine. When Shevchenko asked "How are the people?", he replied that there was nothing to be concerned about: "Some are celebrating a wedding, others are gardening, and others are fishing in the [[Pripyat River]]".<ref name="shevchenko"/>

Shevchenko then spoke overby the phonetelephone to [[Volodymyr Shcherbytsky]], [[General Secretary of the Communist Party of Ukraine|general secretary of the Communist Party of Ukraine]] and ''de facto'' head of state, who said he anticipated a delegation of the state commission headed by [[Boris Shcherbina]], the deputy chairman of the [[Government of the Soviet Union|Council of Ministers of the USSR]].<ref name="shevchenko"/>

[[File:Chernobyl BW 2019 G28.jpg|thumb|Ruins of abandoned apartment buildinghouse in Chernobyl, 2019]]

A commission was established later in the day to investigate the accident. It was headed by [[Valery Legasov]], First Deputy Director of the Kurchatov Institute of Atomic Energy, and included leading nuclear specialist [[Evgeny Velikhov]], hydro-meteorologist [[Yuri Izrael]], radiologist Leonid Ilyin, and others. They flew to [[Boryspil International Airport]] and arrived at the power plant in the evening of 26 April.<ref name="shevchenko"/> By that time two people had already died and 52 were hospitalized. The delegation soon had ample evidence that the reactor was destroyed and extremely high levels of radiation had caused a number of cases of radiation exposure. In the early daylight hours of 27 April, approximately 36&nbsp;hours after the initial blast, they ordered the evacuation of Pripyat. Initially it was decided to evacuate the population for three days; later this was made permanent.<ref name="shevchenko"/>

By 11:00 on 27 April, buses had arrived in Pripyat to start the evacuation.<ref name="shevchenko"/> The evacuation began at 14:00. A translated excerpt of the evacuation announcement follows:

To expedite the evacuation, residents were told to bring only what was necessary, and that they would remain evacuated for approximately three days. As a result, most personal belongings were left behind, and remainresidents therewere only allowed to recover certain items after months had todaypassed. By 15:00, 53,000 people were evacuated to various villages of the [[Kyiv Oblast|Kiev region]].<ref name="shevchenko"/> The next day, talks began for evacuating people from the {{convert|10|km|adj=on}} zone.<ref name="shevchenko"/> Ten days after the accident, the evacuation area was expanded to {{convert|30|km}}.<ref name="MarplesSocialImpact">{{cite book |year=1988 |title=The Social Impact of the Chernobyl Disaster |url=https://archive.org/details/socialimpactof00marp |url-access=registration |location=New York |publisher=St Martin's Press |last=Marples |first=David R.|isbn=9780312024321 }}</ref>{{rp|115, 120–121}} The [[Chernobyl Nuclear Power Plant Exclusion Zone]] has remained ever since, although its shape has changed and its size has been expanded.

The surveying and detection of isolated fallout hotspots outside this zone over the following year eventually resulted in 135,000 long-term evacuees in total agreeing to be moved.<ref name="Nuclear Disasters pp 55"/> The years between 1986 and 2000 saw the near tripling in the total number of permanently resettled persons from the most severely contaminated areas to approximately 350,000.<ref>{{cite web |url=http://www.unicef.org/newsline/chernobylreport.pdf |title=Table 2.2 Number of people affected by the Chernobyl accident (to December 2000) |work=The Human Consequences of the Chernobyl Nuclear Accident |page=32 |publisher=UNDP and UNICEF |date=22 January 2002 |access-date=17 September 2010 |archive-url=https://web.archive.org/web/20170201120932/https://www.unicef.org/newsline/chernobylreport.pdf |archive-date=1 February 2017 |url-status=live }}</ref><ref>{{cite web |url=http://www.unicef.org/newsline/chernobylreport.pdf |title=Table 5.3: Evacuated and resettled people |work=The Human Consequences of the Chernobyl Nuclear Accident |page=66 |publisher=UNDP and UNICEF |date=22 January 2002 |access-date=17 September 2010 |archive-url=https://web.archive.org/web/20170201120932/https://www.unicef.org/newsline/chernobylreport.pdf |archive-date=1 February 2017 |url-status=live }}</ref>

[[File:SPOT-1-1986-05-01-Tchernobyl-PAN.jpg|thumb|upright=1.6|Picture taken by French satellite [[SPOT (satellite)|SPOT-1]] on 1 May 1986]]

Evacuation began one and a half days before the accident was publicly acknowledged by the Soviet Union. In the morning of 28 April, radiation levels set off alarms at the [[Forsmark Nuclear Power Plant]] in [[Sweden]],<ref>{{cite news |title=LIVING WITH CATASTROPHE |date=10 December 1995 |url=https://www.independent.co.uk/arts-entertainment/living-with-catastrophe-1524915.html |website=[[The Independent]] |access-date=8 February 2019 |archive-url=https://web.archive.org/web/20190423140441/https://www.independent.co.uk/arts-entertainment/living-with-catastrophe-1524915.html |archive-date=23 April 2019 |url-status=live }}</ref><ref name="Sveriges"/> over {{convert|1000|km}} from the Chernobyl Plant. Workers at Forsmark reported the case to the [[Swedish Radiation Safety Authority]], which determined that the radiation had originated elsewhere. That day, the Swedish government contacted the Soviet government to inquire about whether there had been a nuclear accident in the Soviet Union. The Soviets initially denied it,. and itIt was only after the Swedish government suggested they were about to file an official alert with the [[International Atomic Energy Agency]], that the Soviet government admitted that an accident had taken place at Chernobyl.<ref name="Sveriges">{{cite web |url=http://sverigesradio.se/sida/artikel.aspx?programid=2054&artikel=4468603 |title=25 years after Chernobyl, how Sweden found out |date=22 April 2011 |website=[[Sveriges Radio]] |access-date=8 November 2018 |archive-url=https://web.archive.org/web/20181109070828/https://sverigesradio.se/sida/artikel.aspx?programid=2054&artikel=4468603 |archive-date=9 November 2018 |url-status=live }}</ref>{{r|schmemann19860429}}

At first, the Soviets only conceded that a minor accident had occurred, but once they began evacuating more than 100,000 people, the full scale of the situation was realized by the global community.<ref>{{Cite journal|last=Baverstock|first=K.|date=26 April 2011|title=Chernobyl 25 years on|journal=BMJ|volume=342|issue=apr26 1|page=d2443|doi=10.1136/bmj.d2443|pmid=21521731|s2cid=12917536|issn=0959-8138}}</ref> At 21:02 the evening of 28 April, a 20-second announcement was read in the TV news programme ''[[Vremya]]'': "There has been an accident at the Chernobyl Nuclear Power Plant. One of the nuclear reactors was damaged. The effects of the accident are being remedied. Assistance has been provided for any affected people. An investigative commission has been set up."<ref name="GalleryTimeline">{{cite web |url=http://chernobylgallery.com/chernobyl-disaster/timeline/ |title=Timeline: A chronology of events surrounding the Chernobyl nuclear disaster |website=The Chernobyl Gallery |access-date=8 November 2018 |date=15 February 2013 |archive-url=https://web.archive.org/web/20150318013918/http://chernobylgallery.com/chernobyl-disaster/timeline/ |archive-date=18 March 2015 |url-status=live|quote='''28 April – Monday 09:30''' – Staff at the Forsmark Nuclear Power Plant, Sweden, detect a dangerous surge in radioactivity. Initially picked up when a routine check reveals that the soles shoes worn by a radiological safety engineer at the plant were radioactive. '''[28 April – Monday] 21:02''' – Moscow TV news announce that an accident has occurred at the Chornobyl Nuclear Power Plant.[...] '''[28 April – Monday] 23:00''' – A Danish nuclear research laboratory announces that an MCA (maximum credible accident) has occurred in the Chernobyl nuclear reactor. They mention a complete meltdown of one of the reactors and that all radioactivity has been released. }}</ref><ref name="vremya">{{YouTube|sC7n_QgJRks|Video footage of Chernobyl disaster on 28 April}} {{in lang|ru}}.</ref>

This was the entire announcement, and the first time the Soviet Union officially announced a nuclear accident. The [[Telegraph Agency of the Soviet Union]] (TASS) then discussed the [[Three Mile Island accident]] and other American nuclear accidents, which [[Serge Schmemann]] of ''The New York Times'' wrote was an example of the common Soviet tactic of [[whataboutism]]. The mention of a commission also indicated to observers the seriousness of the incident,<ref name="schmemann19860429">{{cite news |last=Schmemann |first=Serge |date=29 April 1986 |title=Soviet Announces Nuclear Accident at Electric Plant |page=A1 |newspaper=The New York Times |url=https://www.nytimes.com/learning/general/onthisday/big/0426.html |url-status=live |access-date=26 April 2014 |archive-url=https://web.archive.org/web/20140427011434/http://www.nytimes.com/learning/general/onthisday/big/0426.html |archive-date=27 April 2014}}</ref> and subsequent state radio broadcasts were replaced with classical music, which was a common method of preparing the public for an announcement of a tragedy in the USSR.<ref name="GalleryTimeline"/>

Around the same time, [[ABC News (United States)|ABC News]] released its report about the disaster.<ref>{{cite web |url=http://www.istpravda.com.ua/videos/2011/04/25/36966/ |title=1986: американський ТБ-сюжет про Чорнобиль. Порівняйте з радянським |work=Історична правда |date=25 April 2011 |language=uk |access-date=2 May 2011 |archive-url=https://web.archive.org/web/20110502133614/http://www.istpravda.com.ua/videos/2011/04/25/36966/ |archive-date=2 May 2011 |url-status=live }}</ref> Shevchenko was the first of the Ukrainian state top officials to arrive at the disaster site early on 28 April. There she spoke with members of medical staff and people, who were calm and hopeful that they could soon return to their homes. ShevchenkoShe returned home near midnight, stopping at a radiological checkpoint in Vilcha, one of the first that were set up soon after the accident.<ref name="shevchenko"/>

There was a notification from Moscow that there was no reason to postpone the 1 May [[International Workers' Day]] celebrations in Kiev. (including the annual parade), but onOn 30 April a meeting of the Political bureau of the Central Committee of the CPSU took place to discuss the plan for the upcoming celebration. Scientists were reporting that the radiological background level in Kiev was normal. At the meeting, which was finished at 18:00, itIt was decided to shorten celebrations from the regular three and a half to four hours to under two hours.<ref name="shevchenko"/>

Several buildings in Pripyat were officially kept open after the disaster to be used by workers still involved with the plant. These included the [[Jupiter (Factory)|Jupiter factory]] (which closed in 1996) and the [[Azure Swimming Pool]], used by the [[Chernobyl liquidators]] for recreation during the clean-up (which closed in 1998).

=== Core meltdown risk mitigation ===

[[File:Levels of radioactivity in the lava under the Chernobyl number four reactor 1986.svg|thumb|upright=2.4|Extremely high levels of radioactivity in the lava under the Chernobyl number four reactor in 1986]]

====Bubbler pools====

The smoldering graphite, fuel and other material above, at more than {{convert|1200|C|F}},<ref name=lava2>{{cite journal |doi=10.1134/S1087659609020126 |title=Behavior of melts in the UO2-SiO2 system in the liquid-liquid phase separation region |year=2009 |last1=Petrov |first1=Yu. B. |last2=Udalov |first2=Yu. P. |last3=Subrt |first3=J. |last4=Bakardjieva |first4=S. |last5=Sazavsky |first5=P. |last6=Kiselova |first6=M. |last7=Selucky |first7=P. |last8=Bezdicka |first8=P. |last9=Jorneau |first9=C. |last10=Piluso |first10=P. |journal=Glass Physics and Chemistry |volume=35 |issue=2 |pages=199–204|s2cid=135616447 }}</ref> started to burn through the reactor floor and mixed with molten concrete from the reactor lining, creating [[corium (nuclear reactor)|corium]], a radioactive semi-liquid material comparable to [[lava]].<ref name=Lava1>{{cite journal |doi=10.1134/S1066362208050131 |title=Formation and spread of Chernobyl lavas |year=2009 |last1=Bogatov |first1=S. A. |last2=Borovoi |first2=A. A. |last3=Lagunenko |first3=A. S. |last4=Pazukhin |first4=E. M. |last5=Strizhov |first5=V. F. |last6=Khvoshchinskii |first6=V. A. |journal=Radiochemistry |volume=50 |issue=6 |pages=650–654|s2cid=95752280 }}</ref><ref name=lava3>{{Cite news |last1=Journeau |first1=Christophe |last2=Boccaccio|first2=Eric|last3=Jégou|first3=Claude |last4=Piluso|first4=Pascal |last5=Cognet|first5=Gérard |title=Flow and Solidification of Corium in the VULCANO Facility |publisher=Commissariat à l'énergie atomique et aux énergies alternatives |series=Engineering case studies online|year=2001 |oclc=884784975|citeseerx=10.1.1.689.108 }}</ref> It was feared that if this mixture melted through the floor into the pool of water, the resulting steam production would further contaminate the area or even cause a steamanother explosion, ejecting more radioactive material from the reactor. It became necessary to drain the pool.<ref>{{cite book |last=Medvedev |first=Z. |yearurl=1990 |pages=[https://archive.org/details/legacyofchernoby00medv/page/58 58–59] |title=The Legacy of Chernobyl |url=https://archive.org/details/legacyofchernoby00medv |url-access=registration |publisher=W. W. Norton & CoCompany IncIncorporated |year=1990 |isbn=978-0-393-30814-3 |pages=[https://archive.org/details/legacyofchernoby00medv/page/58 58–59] |url-access=registration}}</ref> These fears ultimately proved unfounded, since corium began dripping harmlessly into the flooded bubbler pools before the water could be removed.<ref name="auto1">{{cite journal |last1=Checherov |first1=Konstantin |title=The Unpeaceful Atom of Chernobyl |journal=Person |date=2006 |issue=1}}</ref> The molten fuel hit the water and cooled into a light-brown ceramic pumice, whose low density allowed the substanceit to float on the water's surface.<ref>{{cite journal |last1name=Checherov |first1=Konstantin |title=The Unpeaceful Atom of Chernobyl |journal=Person |date=2006 |issue=1}}<"auto1"/ref>

Unaware of this fact, the government commission directed that the bubbler pools be drained by opening its [[sluice gates]]. The valves controlling it, however, were located in a flooded corridor in a subterranean annex adjacent to the reactor building. Volunteers in [[diving suit]]s and [[respirator]]s (for protection against radioactive [[aerosol]]s), and equipped with [[dosimeter]]s, entered the knee-deep radioactive water and managed to openopened the valves.<ref name="kramer">{{cite web |last1=Kramer |date=26 April 2016 |first1=Sarah |title=The amazing true story behind the Chernobyl 'suicide squad' that helped save Europe |url=http://www.businessinsider.com/chernobyl-volunteers-divers-nuclear-mission-2016-4 |website=[[Business Insider]] |access-date=7 October 2016 |archive-url=https://web.archive.org/web/20161009180156/http://www.businessinsider.com/chernobyl-volunteers-divers-nuclear-mission-2016-4 |archive-date=9 October 2016 |url-status=live }}</ref><ref name="mkru">{{cite web |last1=Samodelova |first1=Svetlana |script-title=ru:Белые пятна Чернобыля |url=http://www.mk.ru/politics/sng/2011/04/25/584047-belyie-pyatna-chernobyilya.html |website=Московский комсомолец |access-date=7 October 2016 |date=25 April 2011 |language=ru |archive-url=https://web.archive.org/web/20161009160659/http://www.mk.ru/politics/sng/2011/04/25/584047-belyie-pyatna-chernobyilya.html |archive-date=9 October 2016 |url-status=live }}</ref> These were the engineers [[Alexei Ananenko|Oleksiy Ananenko]] and [[Valeri Bezpalov]] (who knew where the valves were), accompanied by the shift supervisor [[Boris Baranov]].<ref name=divers2>{{cite news |date=15 May 1986 |title=Soviets Report Heroic Acts at Chernobyl Reactor With AM Chernobyl Nuclear Bjt |website=[[Associated Press]] |url=https://apnews.com/bfb4a0cf2479ee940116c74141e8a332 |access-date=26 April 2014 |archive-url=https://web.archive.org/web/20140429204527/http://www.apnewsarchive.com/1986/Soviet-Press-Reports-Heroic-Acts-at-Chernobyl-Reactor-With-AM-Chernobyl-Nuclear-Bjt/id-bfb4a0cf2479ee940116c74141e8a332 |archive-date=29 April 2014 |url-status=live }}</ref><ref>{{cite web |url=http://www.myslenedrevo.com.ua/uk/Sci/HistSources/Chornobyl/1986/05/16/ChernobylAdresMuzhestva.html |script-title=ru:Чернобыль: адрес мужества |trans-title=Chernobyl: the address of courage |last1=Zhukovsky |first1=Vladimir |last2=Itkin |first2=Vladimir |last3=Chernenko |first3=Lev |date=16 May 1986 |website=[[Telegraph Agency of the Soviet Union|TASS]] |language=ru |access-date=5 November 2018 |archive-url=https://web.archive.org/web/20181108224502/https://www.myslenedrevo.com.ua/uk/Sci/HistSources/Chornobyl/1986/05/16/ChernobylAdresMuzhestva.html |archive-date=8 November 2018 |url-status=live }}</ref><ref name="Chernobyl 1986, p.178">{{cite book |last=Hawkes |first=Nigel |title=Chernobyl: The End of the Nuclear Dream |date=1986 |page=178 |first=Nigel |last=Hawkes |display-authors=etal |location=London |publisher=Pan Books |isbn=978-0-330-29743-1 |location=London, England |page=178 |display-authors=etal}}</ref> AllNumerous media reports falsely suggested that all three men weredied awardedjust thedays [[Orderlater. ForIn Courage]]fact, byall [[Presidentthree ofsurvived Ukraine|Ukrainianand President]]were awarded the [[PetroOrder PoroshenkoFor Courage]] in May 2018.<ref>{{cite web | url=https://www.ukrinform.ru/rubric-society/2449795-prezident-vrucil-nagrady-geroamlikvidatoram-i-rabotnikam-caes.html | script-title=ru:Президент Петр Порошенко вручил государственные награды работникам Чернобыльской атомной электростанции и ликвидаторам последствий аварии на ЧАЭС. | trans-title=President Petro Poroshenko presented state awards to employees of the Chernobyl nuclear power plant and the liquidators of the consequences of the Chernobyl NPP accident. | language=ru | access-date=28 May 2019 | archive-url=https://web.archive.org/web/20190514115713/https://www.ukrinform.ru/rubric-society/2449795-prezident-vrucil-nagrady-geroamlikvidatoram-i-rabotnikam-caes.html | archive-date=14 May 2019 | url-status=liveusurped }}</ref><ref>{{cite web |url=http://www.souzchernobyl.org/?id=2440 |script-title=ru:Воспоминания старшего инженера-механика реакторного цеха №2 Алексея Ананенка |trans-title=Memoirs of the senior engineer-mechanic of reactor shop №2 Alexey Ananenko |website=Exposing the Chornobyl Myths |language=ru |access-date=8 November 2018 |archive-url=https://web.archive.org/web/20181108224413/http://www.souzchernobyl.org/?id=2440 |archive-date=8 November 2018 |url-status=dead }}</ref>

====Foundation protection measures====

Bolshov'sAs graphitean cooling platealternative, alongsidesubway thebuilders priorand nitrogen[[coal injection proposal,miner]]s were notdeployed usedto followingexcavate a tunnel below the dropreactor into aerialmake temperaturesroom andfor indicativea reportscooling thatsystem. theThe fuelfinal meltmakeshift haddesign stopped.for Itthe wascooling latersystem determinedwas thatto theincorporate fuela hadcoiled flowedformation threeof floors,pipes cooled with awater fewand cubiccovered meterson comingtop towith resta atthin groundthermally levelconductive graphite layer. The precautionarygraphite undergroundlayer channelwould withprevent itsthe activeconcrete above from melting. This graphite cooling plate layer was thereforeto deemedbe encapsulated between two concrete redundantlayers, aseach the{{convert|1|m}} fuelthick wasfor self-coolingstabilisation. TheThis excavationgraphite-concrete was"sandwich" thenwould simplybe filledsimilar within concreteconcept to strengthenlater the[[core foundationcatcher]]s belownow thepart of many nuclear reactor designs.<ref>{{cite newsweb|url=https://wwwpulitzercenter.nytimes.com/2011/03/23org/businessreporting/energycatch-environment/23chernobyl.htmlfalling-core-lessons-chernobyl-russian-nuclear-industry|title=AfterTo Chernobyl,Catch Russia'sa NuclearFalling IndustryCore: EmphasizesLessons Reactorof Safety|first=AndrewChernobyl E.|last=Kramerfor Russian Nuclear Industry|date=2218 MarchSeptember 20112012|newspaperwebsite=The New YorkPulitzer TimesCenter|access-date=29 June 2019|archive-date=29 June 2019|archive-url=https://web.archive.org/web/2019062903311920190629031621/https://wwwpulitzercenter.nytimes.comorg/2011reporting/03/23/business/energycatch-environment/23chernobyl.htmlfalling-core-lessons-chernobyl-russian-nuclear-industry|url-status=live}}</ref>

[[File:Chernobylreactor 1.jpg|thumb|upright=1.2|No. 4 reactor site in 2006 showing the [[Chernobyl Nuclear Power Plant sarcophagus|sarcophagus containment structure]]; Reactor No. 3 is to the left of the smoke stack]]

With the extinguishing of the open air reactor fire, the next step was to prevent the spread of contamination. This could be due to wind action which could carry away loose contamination, and byor birds which could land within the wreckage and then carry contamination elsewhere. In addition, rainwater could wash contamination away from the reactor area and into the sub-surface water table, where it could migrate outside the site area. Rainwater falling on the wreckage could also weakenaccelerate corrosion of steelwork in the remaining reactor structure by accelerating corrosion of steelwork. A further challenge was to reduce the large amount of emitted [[gamma ray|gamma radiation]], which was a hazard to the workforce operating the adjacent reactor No.&nbsp;3.{{citation needed|date=March 2021}}

The solution chosen was to enclose the wrecked reactor by the construction of a huge composite steel and concrete shelter, which became known as the "Sarcophagus". It had to be erected quickly and within the constraints of high levels of ambient gamma radiation. The design started on 20 May 1986, 24 days after the disaster, and construction was from June to late November.<ref>Ebel, Robert E.; Center for Strategic and International Studies (Washington, D.C.) (1994). ''Chernobyl and its aftermath: a chronology of events'' (1994 ed.). CSIS. {{ISBN|978-0-89206-302-4}}.</ref> This major construction project was carried out under the very difficult circumstances of high levels of radiation both from the core remnants and the deposited radioactive contamination around it.

The construction workers had to be protected from radiation, and techniques such as crane drivers working from lead-lined control cabins were employed. The construction work included erecting walls around the perimeter, clearing and surface concreting the surrounding ground to remove sources of radiation and to allow access for large construction machinery, constructing a thick radiation shielding wall to protect the workers in reactor No.&nbsp;3, fabricating a high-rise buttress to strengthen weak parts of the old structure, constructing an overall roof, and provisioning a [[Ventilation (architecture)|ventilation]] extract system to capture any airborne contamination arising within the shelter.{{citation needed|date=March 2021}}

====Investigations of the reactor condition====

During the construction of the sarcophagus, a scientific team, as part of an investigation dubbed "Complex Expedition", re-entered the reactor to locate and contain nuclear fuel to prevent another explosion. These scientists manually collected cold fuel rods, but great heat was still emanating from the core. Rates of radiation in different parts of the building were monitored by drilling holes into the reactor and inserting long metal detector tubes. The scientists were exposed to high levels of radiation and radioactive dust.<ref name="BBCContaining"/>

[[File:Médailles liquidateurs.jpg|thumb|upright=1.2|Soviet badge and medal awarded to [[Chernobyl liquidators]]]]

The official contaminated zones saw a massive clean-up effort lasting seven months.<ref name="MarplesSocialImpact"/>{{rp|177–183}} The official reason for such early, (and dangerous), decontamination efforts, rather than allowing time for natural decay, was that the land must be repopulated and brought back into cultivation. Within fifteen months 75% of the land was under cultivation, even though only a third of the evacuated villages were resettled. Defence forces must have done much of the work. Yet this land was of marginal agricultural value. According to historian David Marples, the administration had a psychological purpose for the clean-up: they wished to forestall panic regarding nuclear energy, and even to restart the Chernobyl power station.<ref name="MarplesSocialImpact"/>{{rp|78–79, 87, 192–193}}

Helicopters regularly sprayed large areas of contaminated land with "Barda", a sticky polymerizing fluid, designed to entrap radioactive dust.<ref>{{cite web |last=Belyaev |first=I. |title=Чернобыль – вахта смерти |trans-title=Chernobyl – Watch of Death |url=https://elib.biblioatom.ru/text/belyaev_chernobyl-vahta-smerti_2009/p58/?hl=%D0%B1%D0%B0%D1%80%D0%B4%D0%B0 |accessdate=2024-05-18 |work=Biblioatom |publisher=Rosatom |language=Ru}}</ref> Although a number of radioactive emergency vehicles were buried in trenches, many of the vehicles used by the liquidators, including the helicopters, still remained, as of 2018, parked in a field in the Chernobyl area. Scavengers have since removed many functioning, but highly radioactive, parts.<ref>{{cite news |url=http://news.bbc.co.uk/2/shared/spl/hi/pop_ups/06/in_pictures_chernobyl0s_silent_graveyards_/html/1.stm |title=Chernobyl's silent graveyards |date=20 April 2006 |website=BBC News |access-date=8 November 2018 |archive-url=https://web.archive.org/web/20181105043521/http://news.bbc.co.uk/2/shared/spl/hi/pop_ups/06/in_pictures_chernobyl0s_silent_graveyards_/html/1.stm |archive-date=5 November 2018 |url-status=live }}</ref> Liquidators worked under deplorable conditions, poorly informed and with poor protection. Many, if not most of them, exceeded radiation safety limits.<ref name="MarplesSocialImpact"/>{{rp|177–183}}<ref name="PetrynaLE">{{cite book |last=Petryna |first=Adriana |year=2002 |title=Life Exposed: Biological Citizens After Chernobyl |location=Princeton, NJ |publisher=Princeton University Press}}</ref>

Although it is difficult to compare releases between the Chernobyl accident andwith a deliberate [[air burst]] nuclear detonation, it hasis stillestimated beenthat estimatedChernobyl thatreleased about four hundred400 times more radioactive material was released from Chernobyl than by the combined [[Atomicatomic bombings of Hiroshima and Nagasaki|atomic bombing of Hiroshima and Nagasaki]] together. However, the Chernobyl accidentdisaster released only released about one -hundredth to one -thousandth of the total amount of radioactivity released during [[nuclear weapons testing]] at the height of the [[Cold War]]; the wide estimate being, due to thevarying differentisotope abundances of isotopes released.<ref>{{cite web |url=http://www.iaea.org/Publications/Booklets/Chernoten/facts.html |title=Facts: The accident was by far the most devastating in the history of nuclear power |website=International Atomic Energy Agency (IAEA) |date=21 September 1997 |access-date=20 August 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110805035908/http://www.iaea.org/Publications/Booklets/Chernoten/facts.html |archive-date=5 August 2011 }}</ref>

Contamination from the Chernobyl accident was scattered irregularly depending on weather conditions, much of it deposited on mountainous regions such as the [[Alps]], the [[Wales|Welsh]] mountains and the [[Scottish Highlands]], where [[Adiabatic process|adiabatic cooling]] caused radioactive rainfall. The resulting patches of contamination were often highly localized, and localized water-flows contributed to large variations in radioactivity over small areas. Sweden and [[Norway]] also received heavy fallout when the contaminated air collided with a cold front, bringing rain.<ref name="GouldFire">{{cite book |last=Gould |first=Peter |year=1990 |title=Fire In the Rain: The Dramatic Consequences of Chernobyl |location=Baltimore, MD |publisher=Johns Hopkins Press |year=1990 |location=Baltimore, Maryland}}</ref>{{rp|43–44, 78}} There was also [[Chernobyl groundwater contamination|groundwater contamination]].

Rain was deliberately [[Cloud seeding|seeded]] over {{convert|10,00010000|km2|sqmi}} of Belarus by the [[Soviet Air Force]] to remove radioactive particles from clouds heading toward highly populated areas. Heavy, black-coloured rain fell on the city of [[Gomel]].<ref>{{cite news |last=Gray |first=Richard |date=22 April 2007 |title=How we made the Chernobyl rain |url=https://www.telegraph.co.uk/news/worldnews/1549366/How-we-made-the-Chernobyl-rain.html |title=How we made the Chernobyl rain |last=Gray |first=Richard |date=22 April 2007 |newspaper=The Daily Telegraph |accessurl-datestatus=27 November 2009 |location=Londonlive |archive-url=https://web.archive.org/web/20091118194620/http://www.telegraph.co.uk/news/worldnews/1549366/How-we-made-the-Chernobyl-rain.html |archive-date=18 November 2009 |urlaccess-statusdate=live27 November 2009 |newspaper=The Daily Telegraph |location=London, England}}</ref> Reports from Soviet and Western scientists indicate that the Belarusian SSR received about 60% of the contamination that fell on the former Soviet Union. However, the 2006 TORCH report stated that up to half of the volatile particles had actually landed outside the former USSR area currently making up of Ukraine, Belarus, and Russia. An unconnected large area in [[Russian Soviet Federative Socialist Republic|Russian SFSR]] south of [[Bryansk]] was also contaminated, as were parts of northwestern [[Ukrainian Soviet Socialist Republic|Ukrainian SSR]]. Studies in surrounding countries indicate that more than one million people could have been affected by radiation.<ref name="WNA-Chernobyl">{{cite web |url=http://world-nuclear.org/info/Safety-and-Security/Safety-of-Plants/Chernobyl-Accident/ |title=Chernobyl Accident 1986 |date=April 2015 |website=[[World Nuclear Association]] |access-date=21 April 2015 |archive-url=https://web.archive.org/web/20150420143903/http://www.world-nuclear.org/info/safety-and-security/safety-of-plants/chernobyl-accident/ |archive-date=20 April 2015 |url-status=live }}</ref> 2016 data from a long-term monitoring program<ref>{{cite web |url=http://wwwzb1.fz-juelich.de/verlagextern1/redirect.asp?id_schriften=48598&URL_DMS=http://dmssrv.zb.kfa-juelich.de/w2p2/autologin1.asp?action=ExpDownload&Path=%5CPublic%20FZJ%5CPublikationen%5CSchriftenreihen%5CEnergie_Umwelt_342.pdf&online=online& |last1=Zoriy |first1=Pedro |last2=Dederichs |first2=Herbert |last3=Pillath |first3=Jürgen |last4=Heuel-Fabianek |first4=Burkhard |last5=Hill |first5=Peter |last6=Lennartz |first6=Reinhard |title=Long-term monitoring of radiation exposure of the population in radioactively contaminated areas of Belarus – The Korma Report II (1998–2015) |volume=342 |work=Schriften des Forschungszentrums Jülich: Reihe Energie & Umwelt / Energy & Environment |publisher=Forschungszentrum Jülich, Zentralbibliothek, Verlag |year=2016 |access-date=21 December 2016 }}{{Dead link|date=March 2022 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> showed a decrease in internal [[Ionizing radiation|radiation exposure]] of the inhabitants of a region in Belarus close to Gomel.

* An early estimate for total [[nuclear fuel]] material released to the environment was {{val|3|1.5}}%; this was later revised to {{val|3.5|0.5}}%. This corresponds to the atmospheric emission of {{convert|6|t|LT ST}} of fragmented fuel.<ref name="OECD1995">{{cite web |url=https://www.oecd-nea.org/rp/chernobyl/chernobyl-1995.pdf |title=Chernobyl, Ten Years On: Assessment of Radiological and Health Impact |year=1995 |website=OECD-NEA |access-date=3 June 2015 |archive-url=https://web.archive.org/web/20150622010906/https://www.oecd-nea.org/rp/chernobyl/chernobyl-1995.pdf |archive-date=22 June 2015 |url-status=live }}</ref>

In a 2007 paper, a robot sent into the reactorNo. itself4 reactor returned with samples of black, [[melanin]]-rich [[radiotrophic fungus|radiotrophic fungi]] that grow on the reactor's walls.<ref>{{cite web |url=https://www.sciencedaily.com/releases/2007/05/070522210932.htm |title='Radiation-Eating' Fungi Finding Could Trigger Recalculation Of Earth's Energy Balance And Help Feed Astronauts |date=23 May 2007 |website=Science Daily |access-date=8 November 2018 |archive-url=https://web.archive.org/web/20181108224505/https://www.sciencedaily.com/releases/2007/05/070522210932.htm |archive-date=8 November 2018}}</ref>

Of the 440,350 wild boar killed in the 2010 hunting season in Germany, approximately one thousand were contaminated with levels of radiation above the permitted limit of 600 becquerels of caesium per kilogram, of dry weight, due to residual radioactivity from Chernobyl.<ref>{{cite news |url=https://www.welt.de/wissenschaft/article12874184/Deutsche-Wildschweine-immer-noch-verstrahlt.html |title=25 Jahre Tschernobyl: Deutsche Wildschweine immer noch verstrahlt |trans-title=25 years of Chernobyl: German wild boars still contaminated |newspaper=[[Die Welt]] |language=de |date=18 March 2011 |access-date=20 August 2011 |archive-url=https://web.archive.org/web/20110831151558/http://www.welt.de/wissenschaft/article12874184/Deutsche-Wildschweine-immer-noch-verstrahlt.html |archive-date=31 August 2011 |url-status=live }}</ref> WhileBecause all''[[Elaphomyces]]'' animalfungal meat contains a natural level ofspecies [[potassium-40Bioaccumulation|bioaccumulate]] at aradiocaesium, similar levelboars of activity, with both wild and farm animals inthe [[ItalyBavarian Forest]] containingthat "415consume ±these 56"deer becquerelstruffles" kg−1are dw"contaminated ofat thathigher levels naturallythan occurringtheir gammaenvironment's emittersoil.<ref>{{citeCite journal |doilast1=10Steiner |first1=M.1016/j.foodcont |last2=Fielitz |first2=U.2012.07.038 |titledate=Radioactivity6 measurementsJune and2009 dosimetric|title=Deer evaluationTruffles in– meatThe ofDominant wildSource andof bredRadiocaesium animalsContamination inof centralWild ItalyBoar |journalurl=Foodhttps://www.radioprotection.org/articles/radiopro/abs/2009/05/radiopro44108/radiopro44108.html Control|journal=Radioprotection |volume=3044 |issue=5 |pages=272–279585–588 |yeardoi=201310.1051/radiopro/20095108 |via=[[EDP Sciences]] |doi-access=free}}</ref> Given that nuclear weapons release a higher ¹³⁵C/¹³⁷C ratio than nuclear reactors, the high ¹³⁵C content in these boars suggests that their radiological contamination can be largely attributed to the Soviet Union's nuclear weapons testing in Ukraine, which peaked during the late 1950s and early 1960s.<ref>{{Cite journal |last1=MeliStäger |first1=Maria AssuntaFelix |last2=CantaluppiZok |first2=ChiaraDorian |last3=DesideriSchiller |first3=DonatellaAnna-Katharina |last4=BenedettiFeng |first4=ClaudioBin |last5=FeduziSteinhauser |first5=LauraGeorg |last6date=Ceccotto30 August 2023 |first6title=FedericaDisproportionately High Contributions of 60 Year Old Weapons-137Cs Explain the Persistence of Radioactive Contamination in Bavarian Wild Boars |last7journal=Fasson[[Environmental Science & Technology]] |first7volume=Andrea57 |issue=36 |pages=13601–13611 |doi=10.1021/acs.est.3c03565 |pmid=37646445 |pmc=10501199 |bibcode=2023EnST...5713601S }}</ref>

====United Kingdom=Human impact ===

[[File:View of Chernobyl taken from Pripyat.JPG|thumb|upright=1.6|[[Pripyat]] lies abandoned with the Chernobyl facility visible in the distance]]

[[File:G radiation-level scale 01.png|thumb|right|upright=1.8| Radiation exposure to first responders at Chernobyl in comparison to a range of situations, from normal activities up to nuclear accident. Each step up the scale indicates a tenfold increase in radiation level.]]

====Acute radiation effects and immediate aftermath====

The only known, causal deaths from the accident involved plant workers in the plant and firefighters. The reactor explosion killed two engineers, and severely burned two28 others whodied werewithin amongthree themonths 237 workers hospitalized in the immediate aftermath. Of the hospitalized workers, 134 exhibited symptoms offrom [[acute radiation syndrome]], including one disputed case(ARS).<ref 28name=":5" of/> theSome hospitalizedsources workersreport dieda withintotal theinitial followingfatality threeof months31,<ref allname="Hallenbeck of1994 whom15" were/><ref hospitalizedname=":4">Mould for(2000), ARSp. and29. 26"The werenumber amongof the 56 patients hospitalized for burns. Among the fatalitiesdeaths in the acute phase (approximatelyfirst three months), all but one patient (with grade 2 ARS) were hospitalized for grade 3 or 4 ARS31."</ref> Sevenincluding outone ofadditional 22off-site patientsdeath withdue gradeto 3coronary ARSthrombosis survived.attributed Only one patient out of 21 with grade 4 ARSto survivedstress.<ref name=":5" />

Long term hazards such as caesium tends to accumulate in vital organs such as the heart,<ref name="KuchinskayaWeWill">{{cite thesis |last1=Kuchinskaya |first1=Olga |title='We will die and become science': the production of invisibility and public knowledge about Chernobyl radiation effects in Belarus |date=2007 |publisher=UCUniversity of California San Diego |url=https://escholarship.org/uc/item/9fb6527b |type=PhD Thesis |page=133 |access-date=14 July 2015 |archive-date=15 July 2015 |archive-url=https://web.archive.org/web/20150715075426/https://escholarship.org/uc/item/9fb6527b |url-status=live }}</ref> while strontium accumulates in bones and may thus be a risk to bone-marrow and [[lymphocyte]]s.<ref name="TORCH"/>{{rp|8}} Radiation is most damaging to cells that are actively dividing. In adult mammals cell division is slow, except in hair follicles, skin, bone marrow and the gastrointestinal tract, which is why vomiting and hair loss are common symptoms of acute radiation sickness.<ref name="MycioWormwood">{{cite book |title=Wormwood Forest: A Natural History of Chernobyl |url=https://archive.org/details/wormwoodforest00mary |url-access=registration |last=Mycio |first=Mary |year=2005 |location=Washington, D.C. |publisher=Joseph Henry Press |isbn=978-0-30910-309-1}}</ref>{{rp|42}}

TheNo [[Chernobylsignificant liquidators]],evidence essentiallyof anchanges all-malein [[civilthe defense]]prevalence emergencyof workforce,congenital wouldanomalies go onlinked to fatherthe normalaccident children,has withoutbeen an increasefound in developmental anomaliesBelarus or aUkraine. statisticallyIn significantSweden increaseand inFinland, thestudies frequenciesfound ofno [[germlineassociation mutation]]sbetween inradioactivity theirand [[offspring|progeny]]congenital malformations.<ref name=pmid15725606pmid8516187>{{cite journal |doi=10.10161111/j.mrgentox1365-3016.20041993.11tb00388.002x |pmid=157256068516187 |title=MicrosatelliteThe mutationsChernobyl showaccident, nocongenital increasesanomalies inand theother childrenreproductive of the Chernobyl liquidatorsoutcomes |journal=Mutation Research/Genetic ToxicologyPaediatric and EnvironmentalPerinatal MutagenesisEpidemiology |volume=5817 |issue=1–22 |pages=69–82121–151 |year=20051993 |last1=FuritsuLittle |first1=KatsumiJ.}}</ref> |last2=RyoLarger |first2=Harukostudies, |last3=Yeliseevasuch |first3=Klaudiyaas G.the |last4=ThuyEUROCAT |first4=Ledatabase, Thiassessed Thanhnearly |last5=Kawabataa |first5=Hiroakimillion |last6=Krupnovabirths |first6=Evelinaand V.found |last7=Trusovano |first7=Valentinaimpacts D.from |last8=Rzheutsky |first8=Valery AChernobyl. |last9=NakajimaResearchers |first9=Hirooconcluded |last10=Kartelthat |first10=Nikolaithe |last11=Nomurawidespread |first11=Taisei}}</ref>fear This normality is similarly seen inabout the childreneffects ofon theunborn survivorsfetuses ofwas thenot [[Goiânia accident]]justified.<ref name=pmid21712431>{{cite journal |doi=10.1093/mutageije/ger02828.5.941 |pmid=2171243110597995 |title=TheEvaluation effectof ofthe low-doseimpact exposureof Chernobyl on germlinethe microsatelliteprevalence mutationof ratescongenital anomalies in humans16 accidentallyregions exposedof toEurope. caesium-137EUROCAT inWorking GoianiaGroup |journal=MutagenesisInternational Journal of Epidemiology |volume=2628 |issue=5 |pages=651–655941–948 |year=20111999 |last1=CostaDolk |first1=E. O. AH. |last2=SilvaNichols |first2=D. d. M. e. |last3=Melo |first3=A. V. d. |last4=Godoy |first4=F. R. |last5=Nunes |first5=H. F. |last6=Pedrosa |first6=E. R. |last7=Flores |first7=B. C. |last8=Rodovalho |first8=R. G. |last9=Da Silva |first9=C. C. |last10=Da Cruz |first10=A. D.|doi-access=free }}</ref>

TwoThe anti-nuclear[[Chernobyl advocacyForum]] groupsrevealed havein publicized2004 non-peer-reviewedthat estimatesthyroid thatcancer includeamong mortalitychildren estimateswas forone thoseof whothe weremain exposedhealth toimpacts evenof smallerthe Chernobyl accident, due to amountsingestion of radiation.contaminated Thedairy [[Unionproducts ofand Concernedinhalation Scientistsof [[Iodine-131]]. (UCS)More calculatedthan that4,000 among the hundredscases of millionschildhood ofthyroid peoplecancer exposedwere worldwidereported, but there willwas beno anevidence eventualof 50,000increased excesssolid cancercancers cases,or resultingleukemia. inThe 25,000&nbsp;excessWHO's cancerRadiation Program reported nine deaths, excludingout of the 4,000 thyroid cancer cases.<ref name="ChernobylsLegacy">{{cite web |url=http://www.ucsusaiaea.org/newsPublications/press_releaseBooklets/Chernobyl/chernobyl-cancer-death-toll-0536.htmlpdf |title=Chernobyl's CancerLegacy: Death Toll Estimate More Than Six Times Higher Than the 4000 Frequently CitedHealth, AccordingEnvironmental toand aSocio-Economic New UCS AnalysisImpacts |access-date=2221 April 20112012 |website=[[UnionChernobyl of Concerned Scientists]]Forum |access-datepublisher=8 November 2018IAEA |url-status=dead |archive-url=https://web.archive.org/web/2011060203182920100215212227/http://www.ucsusaiaea.org/newsPublications/press_releaseBooklets/Chernobyl/chernobyl-cancer-death-toll-0536.htmlpdf |archive-date=215 JuneFebruary 20112010 |quote=The UCS analysis is based on radiological data provided by UNSCEAR, and is consistent with the findings of the Chernobyl Forum and other researchers.}}</ref> HoweverBy 2005, theseUNSCEAR calculationsreported arean based on a simple [[linear no-threshold model]] multiplication and the misapplicationexcess of theover [[collective dose]]6,000 whichthyroid thecancer [[Internationalcases Commissionamong onthose Radiological Protection]] (ICRP) states "should not be done"exposed as usingchildren theor collective dose isadolescents.<ref name="inappropriateChernobyl tohealth use in risk projectionseffects".<ref>{{cite bookweb |chapter-url=http://www.iaeaunscear.org/inisunscear/collectionen/NCLCollectionStore/_Public/46/092/46092732chernobyl.pdf |chapter=Imputability of html#Health Effects to Low-Dose Radiation Exposure Situations |last=González |first=Abel J. |page=5 |title=NuclearChernobyl Law inhealth Progresseffects |publisherwebsite=XXI AIDN/INLA Congress |location=Buenos Aires |date=2014UNSCEAR.org |access-date=823 NovemberMarch 2018 |archive-date=16 October 20162011 |archive-url=https://web.archive.org/web/2016101619314120110513235907/http://www.iaeaunscear.org/inisunscear/collectionen/NCLCollectionStore/_Public/46/092/46092732chernobyl.pdfhtml#Health |archive-date=13 May 2011 |url-status=live }}</ref>

InFred 2004Mettler, thea UNradiation collaborativeexpert, [[Chernobylestimated Forum]]9, revealed thyroid cancer among children to be one of the main health impacts from the000 Chernobyl accident. This is due to the ingestion of contaminated dairy products, along with the inhalation of the short-lived,related highlycancer radioactivedeaths isotopeworldwide, [[Iodine-131]]. Innoting that publication,while moresmall thanrelative 4,000&nbsp;cases of childhoodto thyroidnormal cancer wererisks, reported.the Itnumbers isare important to note that there was no evidence of an increaselarge in solidabsolute cancers or leukemia. It said that there was an increase in psychological problems among the affected populationterms.<ref name="ChernobylsLegacyMettler">{{cite webjournal |last=Mettler |first=Fred |url=http://www.iaea.org/Publications/BookletsMagazines/ChernobylBulletin/chernobylBull472/htmls/chernobyls_legacy2.pdfhtml |title=Chernobyl's Legacy: Health,|journal=IAEA EnvironmentalBulletin and|volume=47 Socio-Economic Impacts|number=2 |access-date=2120 AprilAugust 2012 |website=Chernobyl Forum |publisher=IAEA2011 |url-status=dead |archive-url=https://web.archive.org/web/2010021521222720110805035918/http://www.iaea.org/Publications/BookletsMagazines/ChernobylBulletin/Bull472/htmls/chernobylchernobyls_legacy2.pdfhtml |archive-date=155 FebruaryAugust 20102011 }}</ref> The WHO'sreport Radiationhighlighted Programthe risks to mental health from exaggerated radiation fears, reportednoting that labeling the 4,000affected casespopulation as "victims" contributed to a sense of thyroidhelplessness.<ref cancername="ChernobylsLegacy"/> resultedMettler inalso ninecommented deathsthat 20 years later, the population remained unsure about radiation effects, leading to harmful behaviors.<ref name="who.intMettler"/>

TheA Germanstudy affiliateby ofGreenpeace theestimated [[anti-nuclear]]10,000–200,000 energyadditional organizationdeaths in Belarus, Russia, and Ukraine from 1990 to 2004.<ref name="greenpeace2006">{{cite web |url=httpshttp://www.ippnwgreenpeace.euorg/eninternational/nuclear-energy-andGlobal/international/planet-security2/artikelreport/8f469763ccbfdf176d66611c425ad9b22006/4/why-nuclear-energy-is-not-an-answerchernobylhealthreport.htmlpdf |title=WhyThe nuclearChernobyl energyCatastrophe. isConsequences noton anHuman answer to global warmingHealth |access-dateyear=29 June 20192006 |first=Alex |last=Rosen |workwebsite=[[International Physicians for the Prevention of Nuclear War|IPPNWGreenpeace]] |archiveaccess-date=2915 JuneMarch 20192011 |archive-url=https://web.archive.org/web/2019062914084820110322033230/http://www.ippnwgreenpeace.euorg/eninternational/nuclear-energyGlobal/international/planet-and-security2/artikelreport/8f469763ccbfdf176d66611c425ad9b22006/why-nuclear-energy-is-not-an-answer4/chernobylhealthreport.htmlpdf |archive-date=22 March 2011 |url-status=live }}</ref> theThe ''[[Internationalreport was Physicianscriticized for therelying Preventionon ofnon-peer-reviewed Nuclearstudies, War]]''while suggestGregory that 10Härtl,000 peoplea areWHO affected by thyroid cancer as of 2006spokesman, andsuggested thatits 50,000&nbsp;casesconclusions arewere expectedideologically in the futuremotivated.<ref>{{citeCite webnews |titlelast1=20Hawley years|first1=Charles after|last2=Schmitt Chernobyl&nbsp;–|first2=Stefan The|title=Greenpeace ongoingvs. healththe effectsUnited |website=[[IPPNW]]Nations: |date=AprilThe 2006Chernobyl |access-date=24Body AprilCount 2006Controversy |url=http://www.ippnw-studentsspiegel.orgde/chernobylinternational/research0,1518,411864,00.html |urldate=18 April 2006 |work=[[Der Spiegel]] |access-statusdate=dead15 March 2011 |archive-url=https://web.archive.todayorg/20120629110109web/20110319065148/http://www.ippnw-studentsspiegel.orgde/chernobylinternational/research0,1518,411864,00.html |archive-date=2919 JuneMarch 20122011 |url-status=live }}</ref>

It is difficult to establish the total economic cost of the disaster. According to [[Mikhail Gorbachev]], the Soviet Union spent 18&nbsp;billion&nbsp;Rbls (the equivalent of US$2.5&nbsp;billion at that time, or ${{Formatprice|{{Inflation|US-GDP|2500000000|1986}}}} in today's dollars{{Inflation-fn|US-GDP}}) on containment and decontamination, virtually bankrupting itself.<ref name="GorbachevBoC">{{cite AV media |url=https://www.andanafilms.com/catalogueFiche.php?idFiche=255&rub=Toutes%20les%20fiches%20films |title=The battle of Chernobyl |date=2006 |publisher=Play Film / Discovery Channel |people=Johnson, Thomas (author/director)}} (see 1996 interview with Mikhail Gorbachev).</ref> In 2005, the total cost over 30&nbsp; years for Belarus which includes the monthly payments to liquidators, was estimated at US$235&nbsp;billion;.<ref name="ChernobylsLegacy"/> about ${{Formatprice|{{Inflation|US-GDP|235000000000|2005}}}} in today's dollars given inflation rates.{{Inflation-fn|US-GDP}} Gorbachev inlater Aprilwrote 2006 wrotethat "Thethe nuclear meltdown at Chernobyl 20 years ago this month, even more than my launch of [[perestroika]], ...was perhaps the real cause of the collapse of the Soviet Union."<ref>{{Cite web |last=Gorbachev, |first=Mikhail (21 April |date=2006). [https://www.japantimes.co.jp/opinion/2006/-04/-21/commentary/world-commentary/turning-point-at-chernobyl/#:~:text |title=MOSCOW%20%E2%80%94%20The%20nuclear%20meltdown%20at,Soviet%20Union%20five%20years%20later.&text=This%20would%20be%20in%20the,established%20in%20the%20Soviet%20Union "Turning Pointpoint at Chernobyl."] {{Webarchive|url=https://web.archive.org/web/20200805202658/https://www.japantimes.co.jp/opinion/2006/04/21/commentary/world-commentary/turning-point-at-chernobyl/#:~:text=MOSCOW%20%E2%80%94%20The%20nuclear%20meltdown%20at,Soviet%20Union%20five%20years%20later.&text=This%20would%20be%20in%20the,established%20in%20the%20Soviet%20Union |access-date=52024-05-24 August|website=The 2020 }} ''Japan Times''. Retrieved 19 October 2020.|language=en}}</ref>

Ongoing costs areremain well knownsignificant; in their 2003–2005 report, the [[The Chernobyl Forum]] stated that between five and seven percent of government spending in Ukraine is still related to Chernobyl, while in Belarus, more thanover $13&nbsp;billion is thought to have beenwas spent between 1991 and 2003, with 22% of national budget having been Chernobyl-related in 1991, falling to six percent by 2002.<ref name="ChernobylsLegacy" /> In 2018, Ukraine spent five to seven percent of its national budget on recovery activities related to the Chernobyl disaster.<ref name=":0">{{Cite web|url=https://news.un.org/en/story/2019/04/1037451|title=Chernobyl nuclear disaster-affected areas spring to life, 33 years on|date=26 April 2019|website=UN News|language=en|access-date=28 April 2019|archive-url=https://web.archive.org/web/20190428013533/https://news.un.org/en/story/2019/04/1037451|archive-date=28 April 2019|url-status=live}}</ref> OverallThe economic loss is estimated at $235&nbsp;billion in Belarus.<ref name=":0" /> Much of the current cost relates to the payment of Chernobyl-related social benefits to some seven million people across the three countries.<ref name="ChernobylsLegacy" />

A significant economic impact at the time was the removal of {{convert|784320|ha|acre|abbr=on}} of agricultural land and {{convert|694200|ha|acre|abbr=on}} of forest from production. While much of this has been returned to use, agricultural production costs have risen due to the need for special cultivation techniques, fertilizers and additives.<ref name="ChernobylsLegacy"/> Politically, the accident gavewas greatsignificant significance tofor the new Soviet policy of [[glasnost]],<ref name="ShlyGlasnost">{{cite journal |doi=10.1080/00139157.1992.9931445 |title=Chernobyl and Glasnost: The Effects of Secrecy on Health and Safety |year=1992 |last1=Shlyakhter |first1=Alexander |last2=Wilson |first2=Richard |journal=Environment: Science and Policy for Sustainable Development |volume=34 |issue=5 |page=25|bibcode=1992ESPSD..34e..25S }}</ref> and helped forge closer Soviet–US relations at the end of the Cold War, through bioscientific cooperation.<ref name="PetrynaLE"/>{{rp|44–48}} The disaster also became a key factor in the [[dissolution of the Soviet Union]] in 1991, and a major influence in shapingshaped the 'new' [[Eastern Europe]].<ref name="PetrynaLE"/>{{rp|20–21}} Gorbachev stated that "More than anything else, (Chernobyl) opened the possibility of much greater freedom of expression, to the point that the (Soviet) system as we knew it could no longer continue."<ref>{{Additionalcite citationweb |last=Gorbachev |first=Mikhail needed|date=July21 2019April 2006 |title=Turning point at Chernobyl |url=https://www.japantimes.co.jp/opinion/2006/04/21/commentary/world-commentary/turning-point-at-chernobyl/}}</ref>

[[File:Radiant Mayday-Demo after CHERNOBYL.jpg|thumb|Anti-nuclear protest after the Chernobyl disaster on [[international Workers' Day|May Day]], 1986 in [[West Berlin]]]]

The Chernobyl accident attracted a great deal of interest. Because of the distrust that many people{{who|date=June 2020}} had in the Soviet authorities, which engaged in a major cover-up of the disaster, a great deal of debate about the situation at the site occurred in the [[First World]] during the early days of the event. Because of defective intelligence based on satellite imagery, it was thought that unit number three had also had a dire accident.{{citation needed|date=May 2013}} Journalists mistrusted many professionals, and they in turn encouraged the public to mistrust them.<ref name="kasperson160"/>

[[File:Anti-Atom-Demo Berlin Potsdamer Platz 2011-03-26.jpg|thumb|Nuclear power protest in [[Berlin]], 2011]]

The accident also raised concerns about the cavalier [[safety culture]] in the Soviet nuclear power industry, slowing industry growth and forcing the Soviet government to become less secretive about its operating procedures.<ref name=Kagarlitsky>{{cite book |title=The New Detente: Rethinking East-West Relations |chapter=Perestroika: The Dialectic of Change |last=Kagarlitsky |first=Boris |editor1-last=Kaldor |editor1-first=Mary |editor1-link=Mary Kaldor |editor2-last=Holden |editor2-first=Gerald |editor3-last=Falk |editor3-first=Richard A. |editor3-link=Richard A. Falk |year=1989 |publisher=United Nations University Press |isbn=978-0-86091-962-9}}</ref>{{efn|"No one believed the first newspaper reports, which patently understated the scale of the catastrophe and often contradicted one another. The confidence of readers was re-established only after the press was allowed to examine the events in detail without the original censorship restrictions. The policy of openness ([[glasnost]]) and 'uncompromising criticism' of outmoded arrangements had been proclaimed at the 27th Congress (of the [[Communist Party of Soviet Union]]), but it was only in the tragic days following the Chernobyl disaster that glasnost began to change from an official slogan into an everyday practice. The truth about Chernobyl that eventually hit the newspapers opened the way to a more truthful examination of other social problems. More and more articles were written about drug abuse, crime, corruption and the mistakes of leaders of various ranks. A wave of 'bad news' swept over the readers in 1986–87, shaking the consciousness of society. Many were horrified to find out about the numerous calamities of which they had previously had no idea. It often seemed to people that there were many more outrages in the epoch of [[perestroika]] than before although, in fact, they had simply not been informed about them previously." Kagarlitsky 1989, pp.&nbsp;333–334.}} The government coverup of the Chernobyl disaster was a catalyst for [[glasnost]], which "paved the way for reforms leading to the Soviet collapse."<ref>{{cite news |title=Chernobyl cover-up a catalyst for glasnost |url=httphttps://www.nbcnews.com/id/12403612/ns/world_news-europe/t/chernobyl-cover-up-catalyst-glasnost/wbna12403612 |date=24 April 2006 |agency=Associated Press |website=[[NBC News]] |access-date=21 June 2015 |archive-url=https://web.archive.org/web/20150621102111/http://www.nbcnews.com/id/12403612/ns/world_news-europe/t/chernobyl-cover-up-catalyst-glasnost/ |archive-date=21 June 2015 |url-status=live }}</ref> Numerous structural and construction quality issues, as well as deviations from the original plant design, had been known to the KGB since at least 1973 and passed on to the [[Central Committee of the Communist Party of the Soviet Union|Central Committee]], which took no action and [[Classified information|classified]] the information.<ref>{{Cite web |urllast=http://euromaidanpress.com/Government Authorities or Not Fully Developed |date=12 June 2018/06/12/chernobyl-nuclear-plant-was-doomed-declassified-kgb-documents-reveal/ |title=Chornobyl nuclear disaster was tragedy in the making, declassified KGB files show {{!}} |lasturl=Developedhttp://euromaidanpress."|first=Government Authorities or Not Fully|date=com/2018/06/12 June 2018|website=Euromaidan Press|language=en/chernobyl-US|accessnuclear-date=18plant-was-doomed-declassified-kgb-documents-reveal/ June 2019|archiveurl-datestatus=18live June 2019|archive-url=https://web.archive.org/web/20190618120916/http://euromaidanpress.com/2018/06/12/chernobyl-nuclear-plant-was-doomed-declassified-kgb-documents-reveal/ |urlarchive-statusdate=live18 June 2019 |access-date=18 June 2019 |website=Euromaidan Press |language=en-US}}</ref>

In Italy, the Chernobyl accident was reflected in the outcome of the [[1987 Italian nuclear power referendum|1987 referendum]]. As a result of that referendum, Italy began phasing out its nuclear power plants in 1988, a decision that was effectively [[Nuclear power in Italy|reversed in 2008]]. A [[2011 Italian referendums#Nuclear power|2011 referendum]] reiterated Italians' strong objections to nuclear power, thus abrogating the government's 2008 decision.{{citation needed|date=April 2022}}

In Germany, the Chernobyl accident led to the creation of a [[German federal environment ministry|federal environment ministry]], after several states had already created such a post. The post has been held, among others, by [[Angela Merkel]] who would later become leader of the opposition and then chancellor. The German environmental minister was given the authority over reactor safety as well, a responsibility the current minister still holds today. The Chernobyl disaster is also credited with strengthening the [[anti-nuclear movement in Germany]], which culminated in the decision to [[Nuclear power phase-out#Germany|end the use of nuclear power]] made by the 1998–2005 Schröder government.<ref>Hanneke Brooymans. France, Germany: A tale of two nuclear nations, ''The Edmonton Journal'', 25 May 2009.</ref> A temporary reversal of this policy wasended in turn reverted afterwith the [[Fukushima nuclear disaster]].

In direct response to the Chernobyl disaster, a conference to create a [[Convention on Early Notification of a Nuclear Accident]] was called in 1986 by the [[International Atomic Energy Agency]]. The resulting treaty has bound signatory member statesmembers to provide notification of any [[nuclear and radiation accidents]] that occur within its jurisdiction that could affect other states, along with the [[Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency]].{{citation needed|date=April 2022}}

The Chernobyl disaster, along with the [[Challenger disaster|space shuttle ''Challenger'' disaster]], the [[Three Mile Island accident]], and the [[Bhopal disaster]] havehas been used together as a case studies, both by the US government and by third parties,study in research concerning the root causes of such disasters, such as sleep deprivation<ref>{{Cite journal |pmc = 2517096|year = 1988|last1 = Mitler|first1 = M. M.|title = Catastrophes, Sleep, and Public Policy: Consensus Report|journal = Sleep|volume = 11|issue = 1|pages = 100–109|last2 = Carskadon|first2 = M. A.|last3 = Czeisler|first3 = C. A.|last4 = Dement|first4 = W. C.|last5 = Dinges|first5 = D. F.|last6 = Graeber|first6 = R. C.|pmid = 3283909|doi = 10.1093/sleep/11.1.100}}</ref> and mismanagement.<ref>{{Cite web |url=https://www.bhopal.net/old_bhopal_web/bhopalnet/presscoverage/houstonchronicle/archive/19861203-challenger.html |title=Challenger disaster compared to Bhopal, Chernobyl, TMI |access-date=7 May 2019 |archive-url=https://web.archive.org/web/20190507075707/https://www.bhopal.net/old_bhopal_web/bhopalnet/presscoverage/houstonchronicle/archive/19861203-challenger.html |archive-date=7 May 2019 |url-status=live }}</ref>

=== CulturalIn impactpopular culture ===

The Chernobyl tragedy has inspired many artists across the world to create works of art, animation, video games, theatre and cinema about the disaster. The HBO series ''[[Chernobyl (miniseries)|Chernobyl]]'' and the book ''[[Voices from Chernobyl]]'' by the Ukrainian-Belarusian writer [[Svetlana Alexievich]] are two well-known works that talk about the catastrophe that destroyed millions of lives.<ref>{{Cite web |title=Exploring how Chernobyl impacted Ukrainian cultural heritage |date=13 October 2021 |url=https://www.clotmag.com/news/insight-exploring-how-chernobyl-impacted-ukrainian-cultural-heritage-part-2 |access-date=2022-04-29 April 2022 |language=en-GB}}</ref> The Ukrainian artist Roman Gumanyuk created a series of artworks called "Pripyat Lights, or Chernobyl shadows" that includes 30 oil paintings about the Chernobyl accident. The series of artwork was, exhibited at the National Fine Art Museum of Kyrgyzstan in [[Bishkek]], the [[A. Kasteyev State Museum of Arts|Kasteev State Museum of Arts]] of Kazakhstan in [[Almaty]], the Vashchenko Art Gallery of Gomel in [[Belarus]], and at the Museum of Chernobyl in Kharkiv in Ukraine in the years 2012–2013.<ref>{{Cite web |date=5 August 2018-08-05 |title=Paintings by artist Roman Gumanyuk |url=http://gumanyuk.com/#!/Gallery |access-date=2022-04-29 April 2022 |website= |archive-url=https://web.archive.org/web/20180805124316/http://gumanyuk.com/#!/Gallery |archive-date=5 August 2018 |url-status=dead}}</ref><ref>{{Cite web |date=2018-08-23 August 2018 |title=Series of artworks Pripyat Lights, or Chernobyl Shadows of artist Roman Gumanyuk |url=http://www.chernobylshadows.com/index.html |access-date=2022-04-29 April 2022 |website= |archive-url=https://web.archive.org/web/20180823224639/http://www.chernobylshadows.com/index.html |archive-date=23 August 2018 |url-status=dead}}</ref>

The video game [[S.T.A.L.K.E.R.: Shadow of Chernobyl|''S.T.A.L.K.E.R.: Shadows of Chernobyl'']] released by [[THQ]] in 2007, is a first-person shooter set in the [[Exclusion zone|Exclusion Zone]].<ref>{{Cite web |title=S.T.A.L.K.E.R.: Shadow of Chernobyl |url=https://www.stalker-game.com/en/?page=gameplay |access-date=2022-04-29 April 2022 |website=www.stalker-game.com}}</ref> A prequel called ''[[S.T.A.L.K.E.R.: Clear Sky]]'' was released in 2008 following with a sequel ''[[S.T.A.L.K.E.R.: Call of Pripyat]]'' released in 2010. Finally, the horror film ''[[Chernobyl Diaries]]'' released in 2012 is about six tourists that hire a tour guide to take them to the abandoned city of [[Pripyat]] where they discover they are not alone.<ref>{{Cite web |title=Chernobyl Diaries |url=https://www.boxofficemojo.com/release/rl1967883777/ |access-date=2022-04-29 April 2022 |website=Box Office Mojo}}</ref>

[[Filmmaking|Filmmakers]] have created documentaries that examine the aftermath of the disaster over the years. Documentaries like the [[Oscar-winning]] ''[[Chernobyl Heart]]'' released in 2003, explore how radiation affected people living in the area and information about the long-term side effects of radiation exposure over the years that include mental disabilities, physical disabilities, and [[genetic mutations]] after the disaster.<ref>{{Cite web |title=Chernobyl Heart (2003) {{!}} The Embryo Project Encyclopedia |url=https://embryo.asu.edu/pages/chernobyl-heart-2003 |access-date=2 May 2022-05-02 |website=embryo.asu.edu}}</ref> ''The Babushkas of Chernobyl'' released in (2015,) is a documentary that explores the story of theabout three women who decided to return to the exclusion zone after the disaster. In the documentary, the Babushkas show the polluted water, their food from radioactive gardens, and explain how they manage to survive in this exclusion zone despite the radioactive levels of it.<ref>{{Cite web |date=14 June 2017-06-14 |title=Review: 'The Babushkas of Chernobyl' |url=https://povmagazine.com/review-the-babushkas-of-chernobyl/ |access-date=2 May 2022-05-02 |website=POV Magazine |language=en-US}}</ref><ref>{{Cite web |title=Home |url=https://thebabushkasofchernobyl.com/ |access-date=2 May 2022-05-02 |website=The Babushkas of Chernobyl |language=en}}</ref> The documentary ''The Battle of Chernobyl'', released in (2006,) shows a rare original footage a day before the disaster in the city of Pripyat, then through different methods the documentary goes in depth on the chronological events that led to the explosion of the reactor No. 4 and the disaster response in which 50,000 men from [[Soviet Union]] engaged to liquidate the radioactivity of the damaged reactor.<ref>{{Cite web |title=The best documentaries about Chernobyl |url=https://guidedoc.tv/blog/the-best-documentaries-about-chernobyl/ |access-date=2 May 2022-05-02 |website=Guidedoc.tv |language=en}}</ref><ref>{{Citation |last=Johnson |first=Thomas |title=La bataille de Tchernobyl |url=https://www.imdb.com/title/tt1832484/ |series=Passé sous silence |access-date=2 May 2022-05-02|mode=cs1}}</ref> The critically acclaimed 2019 historical drama television miniseries ''[[Chernobyl (miniseries)|Chernobyl]]'' revolves around the disaster and the cleanup efforts that followed.

* {{Annotated link|ChernobylIndividual involvement in the (miniseries)|''Chernobyl'' (miniseries)disaster}}

* {{Annotated[[Consequences link|Individual involvement inof the Chernobyl disaster}} in France]]

{{Further|Bibliography of theUkrainian Post Stalinist Soviet Unionhistory#Chernobyl}}

* [https://web.archive.org/web/20190517230215/https://www.nationalgeographic.com/culture/topics/reference/chernobyl-disaster/ Chernobyl disaster facts and information], by [[National Geographic]]

[[Category:Man-madeINES disastersLevel in7 Belarusaccidents]]

[[Category:Man-made disasters in the Soviet Union]]

[[Category:INESSoviet Level 7 accidentscover-ups]]