Chernobyl Nuclear Power Plant sarcophagus
{{Short description|Structure covering destroyed unit 4 at the Chernobyl Nuclear Power Plant}}
{{About|the original containment|the new containment in place since 2016|Chernobyl New Safe Confinement}}
{{Use dmy dates|date=March 2020}}
{{Infobox building
| name = Chernobyl Nuclear Power Plant Sarcophagus
| native_name = {{langx|uk|Укриття Чорнобильської АЕС}}
| image = Chernobylreactor 1.jpg
| caption = The sarcophagus in 2006. The tall chimney is an original part of the reactor building.
| location = Covering Reactor 4 of the Chernobyl Nuclear Power Plant, within the Chernobyl exclusion zone, near Pripyat
| location_town =
| location_country = Ukraine
| coordinates = {{coord|51.3896|30.0990|display=inline,title|format=dms}}
| start_date = June 1986
| completion_date = November 1986
| demolition_date =
| status = Deteriorated; succeeded by Chernobyl New Safe Confinement
| cost =
| references =
| map_type = Ukraine
| map_caption = Location in Ukraine
| building_type = Confinement shelter
| height =
| alternate_name = Chernobyl Nuclear Power Plant Shelter Structure
}}
The Chernobyl Nuclear Power Plant sarcophagus or Shelter Structure ({{langx|uk|Об'єкт "Укриття"|Ob'yekt "Ukryttya"}}, {{langx|ru|Объект «Укрытие»|Ob"yekt «Ukrytiye»}}) is a massive steel and concrete structure covering the nuclear reactor number 4 building of the Chernobyl Nuclear Power Plant. Built in the aftermath of the 1986 Chernobyl disaster, the sarcophagus was designed to limit radioactive contamination of the environment by encasing the most dangerous area and protecting it from climate exposure.{{cite web|url=http://www.chernobyl-international.com/about-chernobyl/chernobyl-sarcophagus.html|title=Chernobyl Sarcophagus|publisher=Chernobyl International|access-date=30 November 2010|url-status=dead|archive-url=https://web.archive.org/web/20141204145008/http://www.chernobyl-international.com/about-chernobyl/chernobyl-sarcophagus.html|archive-date=4 December 2014}} The sarcophagus locked in an estimated {{val|200|u=tons}} of radioactive lava-like corium, {{val|30|u=tons}} of highly contaminated dust and {{val|16|u=tons}} of uranium and plutonium.
Structurally, the sarcophagus is largely supported by the damaged reactor building. By 1996, the structure had deteriorated to the point where numerous stabilization measures were required. Internal radiation levels were estimated to be as high as {{val|10000|u=röntgens}} per hour in certain areas (normal background radiation in cities is usually around {{val|20|-|50|u=microröntgens}} per hour, and a lethal dose is {{val|500|u=röntgens}} over 5 hours).{{harvnb|Marples|1996|p=30}}. By 2017, the sarcophagus was surrounded by the New Safe Confinement structure, which is designed to protect the environment while the sarcophagus undergoes demolition and the nuclear cleanup continues. The reactor site is located within a large restricted area known as the Chernobyl Exclusion Zone.
The original Russian name is {{lang|ru|Объект "Укрытие"}} ({{transliteration|ru|Obyekt Ukrytiye}}),Code name given under the Soviet secrecy procedures. which means {{em|sheltering}} or {{em|covering}}, as opposed to sarcophagus.
Construction
File:IAEA 02790050 (5612554065).jpg
The design of the sarcophagus started on 20 May 1986, 24 days after the disaster. Subsequent construction lasted for 206 days, from June to late November of the same year. Due to high radiation levels, it was impossible to directly screw down the nuts and bolts or apply any direct welding to the sarcophagus, so this work was done remotely where possible. The seams of the sarcophagus, however, could not be fully sealed.
The entire construction process consisted of eight stages:
- Clearing and concreting of territory around reactor unit 4
- Erection of initial reinforced concrete protective walls around the perimeter
- Construction of separation walls between units 3 and 4
- Cascade wall construction
- Covering of the turbine hall
- Mounting of a high-rise buttress wall
- Erection of supports and installation of a reactor compartment covering
- The installation of a ventilation system.
More than {{convert|400000|m3}} of concrete and 7,300 tonnes of metal framework were used during the erection of the sarcophagus.{{harvnb|Ebel|1994|p=1}}. The building ultimately enclosed {{convert|740000|m3}} of heavily contaminated debris inside, together with contaminated soil.
On 2 October 1986 a Mil Mi-8 Helicopter crashed while engaged in cleanup operations.{{cite web |title=Mi-8 Helicopter crash incident |url=https://asn.flightsafety.org/wikibase/168706 |website=Flightsafety |access-date=26 October 2024}}
On 11 October 1986, the Soviet Governmental Commission accepted a report entitled: "Conclusion on Reliability and Durability of a Covering Constructions and Radiation Safety of Chernobyl NPP Unit 4 Reactor Compartment".{{cite news|url=http://www.chernobyl.by/shelter/33-sooruzhenie.html|script-title=ru:Объект "Укрытие": Сооружение|publisher =Chernobyl.by|access-date=2 December 2010|language=ru|newspaper=Чернобыль.by - Chernobyl.by }}{{Verify source|date=November 2016|reason=The link is broken, and the Cyrillic title is less than 1/4 the length of the English one. trans-title=, please?}}
The sarcophagus has over 60 bore holes to allow observation of the interior of the core.{{harvnb|Marples|Risovanny|1990|p=17}}. In many places the structure was designed to have ventilation shafts to allow some convection inside. Filtration systems have been put in place so that no radioactive material will escape through these holes.
Ongoing issues
File:4th block of the Chernobyl Nuclear Power Plant.jpg
The present shelter is constructed on top of the ruins of the reactor building. The "Mammoth Beam" that supports the roof of the shelter rests partly on the structurally unsound west wall of the reactor building that was damaged by the accident.See [http://video.google.co.uk/videoplay?docid=-5968506788418521112# BBC documentary] {{webarchive|url=https://web.archive.org/web/20120229235859/http://video.google.co.uk/videoplay?docid=-5968506788418521112%23|date=29 February 2012}}. The western end of the shelter roof is supported by a wall at a point designated axis 50. This wall is reinforced concrete and was cracked by the accident.
=Designed stabilisation steel structure=
The DSSS is a yellow steel object that has been placed next to the wrecked reactor; it is 63 meters (207 ft) tall and has a series of cantilevers that extend through the western buttress wall, and is intended to stabilize the sarcophagus.Nuclear Engineering International, July 2007, page 12. This was done because if the wall of the reactor building or the roof of the shelter were to collapse, then large amounts of radioactive dust and particles would be released directly into the atmosphere, resulting in a large new release of radioactivity into the environment. In December 2006 the "Designed Stabilisation Steel Structure" (DSSS) was extended until 50% of the roof load (about 400 tons) was transferred from the axis 50 wall to the DSSS.{{Citation needed|date=May 2009}}
=Upper biological shield=
A further threat to the shelter is the steel and concrete slab that formed the upper biological shield (UBS), situated above the reactor prior to the accident.{{Citation needed|date=May 2009}} This concrete slab was thrown upwards by the explosion in the reactor core and now rests at approximately 15° from vertical. The position of the upper bioshield is considered inherently unsafe, as only debris supports it in its nearly upright position. A collapse of the bioshield would further exacerbate the dust conditions in the shelter, possibly spreading some quantity of radioactive materials out of the shelter, and could damage the shelter itself. The UBS is a disk {{convert|17.7|meters}} in diameter, weighing 1000 tons. The shield is formally called Component E and nicknamed Elena. The twisted fuel bundles still attached to it are called Elena's hair.{{cite web|url=https://www.angelfire.com/extreme4/kiddofspeed/journal/glossary.html|title=Chernobyl Glossary|publisher=Angelfire.com|access-date=22 March 2010}}{{cite book |author=Larabee |first=Ann |url=https://archive.org/details/decadeofdisaster0000lara |title=Decade of disaster |publisher=University of Illinois Press |year=2000 |isbn=978-0-252-06820-1 |page=[https://archive.org/details/decadeofdisaster0000lara/page/50 50] |quote=corium silicate. |access-date=7 November 2019 |url-access=registration}}{{cite web|url=http://www.epa.gov/rpdweb00/rert/chernobyltour/blast_02.html|title=Chernobyl Tour|publisher=United States Environmental Protection Agency|date=28 June 2006|access-date=7 November 2019|archive-url=https://web.archive.org/web/20121025221557/http://www.epa.gov/rpdweb00/rert/chernobyltour/blast_02.html|archive-date=25 October 2012}}
Replacement
{{Main|Chernobyl New Safe Confinement}}
File:1121-Txernobylgo zentral nuklearrerako sarkofago berria-en.svg
On 22 December 1988, Soviet scientists announced that the sarcophagus would only last 20–30 years before requiring restorative maintenance work. In 1998, with the help of the European Bank for Reconstruction and Development, a conservation programme was completed that included securing the roof beams from collapsing. Nonetheless, the rain-induced corrosion of supporting beams still threatens the sarcophagus' integrity.{{cite web|url=http://www.greenpeace.org/international/en/campaigns/nuclear/nomorechernobyls/what-happened-in-chernobyl/|title=What happened in Chernobyl?|publisher =Greenpeace|access-date=30 November 2010}} It was revealed that the water is leaking through the sarcophagus via holes in its roof, becoming radioactively contaminated, and then seeping through the reactor's floor into the soil.
The Chernobyl New Safe Confinement, rolled into place in November 2016, allows for the dismantling of the sarcophagus and for radioactive material to be removed.{{cite web|url=https://www.rferl.org/a/inside-chernobyl-nuclear-power-plant-conferment-shelter-photo/29583945.html|title=Under The Shield: Inside Chernobyl's New Safe Confinement|website=RadioFreeEurope/RadioLiberty|date=6 November 2018 }}{{harvnb|Wood|2007|p=63}}. The containment was expected to cover the existing sarcophagus in 2015. However, delays and a €100 million funding gap caused a yearlong delay, before being moved into place in November 2016.
{{As of|2025|}}, the New Safe Confinement was completed and in operation; it was damaged by a drone attack in February 2025.{{Cite web |last=Edwards |first=Daria Tarasova-Markina, Tim Lister, Christian |date=2025-02-14 |title=Ukraine says Russia drone attack hits Chernobyl nuclear plant, radiation levels normal |url=https://edition.cnn.com/2025/02/14/europe/russia-ukraine-drones-chernobyl-intl-hnk |access-date=2025-03-08 |website=CNN |language=en}}{{Cite web |date=3 January 2017 |title=A vast new tomb for the most dangerous waste in the world |url=https://www.bbc.com/future/article/20170101-a-new-tomb-for-the-most-dangerous-disaster-site-in-the-world |access-date=8 March 2025 |website=BBC |language=en-GB}}
References
=Notes=
{{reflist}}
=Further reading=
- {{cite book|author1=Асмолов В. Г. |author2=Козлова Е. А. |url=http://elib.biblioatom.ru/text/asmolov_neokonchennaya-povest_2018/go,4/|title= Неоконченная повесть...|place=М.|year=2018|isbn=978-5-88777-064-2|ref=Асмолов, Козлова|language=ru}} Total pages: 336
- {{cite book |last=Ebel|first=Robert E.; Center for Strategic and International Studies (Washington, D.C.)| title = Chernobyl and its aftermath: a chronology of events|edition=1994|year=1994| publisher = CSIS| isbn= 978-0-89206-302-4}} Total pages: 43
- {{cite journal | last1=Marples |first1=David R. |last2=Risovanny |first2=Yuri |date=December 1990 |title=Revelations of a Chernobyl Insider |journal=Bulletin of the Atomic Scientists |volume=46 |issue=10 |pages=16–21 | doi=10.1080/00963402.1990.11459915 |bibcode=1990BuAtS..46j..16M |url=https://books.google.com/books?id=8AsAAAAAMBAJ&pg=PA16 |issn=0096-3402|url-access=subscription }}
- {{cite journal|last=Marples|first=David R.|date=May 1996|title=The Decade of Despair|journal=Bulletin of the Atomic Scientists|volume=52|issue=3|pages=20–31|doi=10.1080/00963402.1996.11456623|bibcode=1996BuAtS..52c..20M|url=https://books.google.com/books?id=xAwAAAAAMBAJ|issn=0096-3402|url-access=subscription}}
- {{cite book |last=Wood|first=Janet| title = Nuclear power: Volume 52 of Power engineer|edition=2007|year=2007| publisher = Institution of Engineering and Technology| isbn= 978-0-86341-668-2}} Total pages: 239
External links
- {{cite web |url=http://www.ebrd.com/downloads/research/factsheets/chernobyl25.pdf |title=Chernobyl 25 years on: New Safe Confinement and Spent Fuel Storage Facility |publisher=European Bank for Reconstruction & Development}}
{{Chernobyl disaster}}
Chernobyl Nuclear Power Plant Sarcophagus
Category:Energy infrastructure completed in 1986
Category:Buildings and structures in Pripyat