Global InformationChernobyl disaster information
 | This article may be too long to read and navigate comfortably. When this tag was added, its readable prose size was 18,000 words. (September 2023) |
 Reactor 4 several months after the disaster. Reactor 3 can be seen behind the ventilation stack. | |
 | |
| Date | 26 April 1986 |
|---|---|
| Time | 01:23 MSD (UTC+04:00) |
| Location | Chernobyl Nuclear Power Plant, Pripyat, Chernobyl Raion, Kiev Oblast, Ukrainian SSR, Soviet Union(now Vyshhorod Raion, Kyiv Oblast, Ukraine) |
| Type | Nuclear and Radiation accident |
| Cause | Reactor design and operator error |
| Outcome | INES Level 7 (major accident) |
| Deaths | 2 killed by debris (including 1 missing) and 28 killed by acute radiation sickness. 15 terminal cases of thyroid cancer, with varying estimates of increased cancer mortality over subsequent decades (for more details, see Deaths due to the disaster) |
| Chernobyl disaster |
|---|
 |
The Chernobyl disaster[a] began on 26 April 1986 with the explosion of the No. 4 reactor of the Chernobyl Nuclear Power Plant, near the city of Pripyat in the north of the Ukrainian SSR, close to the border with the Byelorussian SSR, in the Soviet Union.[1] It is one of only two nuclear energy accidents rated at seven—the maximum severity—on the International Nuclear Event Scale, the other being the 2011 Fukushima nuclear accident in Japan. The initial emergency response and subsequent mitigation efforts involved more than 500,000 personnel and cost an estimated 18 billion roubles—roughly US$68 billion in 2019, adjusted for inflation.[2] It is considered the worst nuclear disaster in history.[3][4][5][6]
The accident occurred during a test of the steam turbine's ability to power the emergency feedwater pumps in the event of a simultaneous loss of external power and coolant pipe rupture. Following an accidental drop in reactor power to near-zero, the operators restarted the reactor in preparation for the turbine test with a prohibited control rod configuration. Upon successful completion of the test, the reactor was then shut down for maintenance. Due to a variety of factors, this action resulted in a power surge at the base of the reactor which brought about the rupture of reactor components and the loss of coolant. This process led to steam explosions and a meltdown, which destroyed the containment building. This was followed by a reactor core fire which lasted until 4 May 1986, during which airborne radioactive contaminants were spread throughout the USSR and Europe.[7][8] In response to the initial accident, a 10-kilometre (6.2 mi) radius exclusion zone was created 36 hours after the accident, from which approximately 49,000 people were evacuated, primarily from Pripyat. The exclusion zone was later increased to a radius of 30 kilometres (19 mi), from which an additional ~68,000 people were evacuated.[9]
Following the reactor explosion, which killed two engineers and severely burned two more, an emergency operation to put out the fires and stabilize the surviving reactor began, during which 237 workers were hospitalized, of whom 134 exhibited symptoms of acute radiation syndrome (ARS). Among those hospitalized, 28 died within the following three months. In the following 10 years, 14 more workers (9 of whom had been hospitalized with ARS) died of various causes mostly unrelated to radiation exposure.[10] 15 childhood thyroid cancer deaths were attributed to the disaster as of 2011[update].[11][12] A United Nations committee found that to date fewer than 100 deaths have resulted from the fallout.[13] Model predictions of the eventual total death toll in the coming decades vary. The most widely cited study conducted by the World Health Organization in 2006 predicted 9,000 cancer-related fatalities in Ukraine, Belarus and Russia.[14]
Following the disaster, Pripyat was abandoned and eventually replaced by the new purpose-built city of Slavutych. The Chernobyl Nuclear Power Plant sarcophagus was built by 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, this containment structure was only intended to last for 30 years, 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 aims to enable the removal of both the sarcophagus and the reactor debris while containing the radioactive materials inside. Clean-up is scheduled for completion by 2065.[15]
Cite error: There are <ref group=lower-alpha> tags or {{efn}} templates on this page, but the references will not show without a {{reflist|group=lower-alpha}} template or {{notelist}} template (see the help page).
- ^ "Accident of 1986". Chornobyl NPP. Retrieved 14 July 2022.
- ^ "Chernobyl: Assessment of Radiological and Health Impact, 2002 update; Chapter II – The release, dispersion and deposition of radionuclides" (PDF). OECD-NEA. 2002. Archived (PDF) from the original on 22 June 2015. Retrieved 3 June 2015.
- ^ "The Chornobyl Accident". United Nations Scientific Committee on the Effects of Atomic Radiation. Retrieved 19 September 2023.
- ^ "A Brief History of Nuclear Accidents Worldwide". www.ucsusa.org. 1 October 2013. Retrieved 19 September 2023.
- ^ Steinhauser, Georg; Brandl, Alexander; Johnson, Thomas E. (2014). "Comparison of the Chernobyl and Fukushima nuclear accidents: A review of the environmental impacts". Science of The Total Environment. 470–471: 800–817. doi:10.1016/j.scitotenv.2013.10.029.
- ^ Lallanilla, Marc; Geggel, Laura (18 April 2023). "Chernobyl: The world's worst nuclear disaster". livescience.com. Retrieved 19 September 2023.
- ^ McCall, Chris (April 2016). "Chernobyl disaster 30 years on: lessons not learned". The Lancet. 387 (10029): 1707–1708. doi:10.1016/s0140-6736(16)30304-x. ISSN 0140-6736. PMID 27116266. S2CID 39494685.
- ^ "Chernobyl-Born Radionuclides in Geological Environment". Groundwater Vulnerability. Special Publications. John Wiley & Sons, Inc. 2014. pp. 25–38. doi:10.1002/9781118962220.ch2. ISBN 978-1-118-96222-0.
- ^ Steadman, Philip; Hodgkinson, Simon (1990). Nuclear Disasters & The Built Environment: A Report to the Royal Institute. Butterworth Architecture. p. 55. ISBN 978-0-40850-061-6.
- ^ Wagemaker, G.; Guskova, A.K.; Bebeshko, V.G.; Griffiths, N.M.; Krishenko, N.A. (1996). "Clinically Observed Effects in Individuals Exposed to Radiation as a Result of the Chernobyl Accident". One Decade After Chernobyl: Summing up the Consequences of the Accident, Proceedings of an International Conference, Vienna.: 173–198.
- ^ "Chernobyl 25th anniversary – Frequently Asked Questions" (PDF). World Health Organization. 23 April 2011. Archived (PDF) from the original on 17 April 2012. Retrieved 14 April 2012.
- ^ "Chernobyl: the true scale of the accident". World Health Organization. 5 September 2005. Archived from the original on 25 February 2018. Retrieved 8 November 2018.
- ^ "UNSCEAR assessments of the Chernobyl accident". www.unscear.org. Archived from the original on 13 May 2011. Retrieved 13 September 2007.
- ^ "World Health Organization report explains the health impacts of the world's worst-ever civil nuclear accident". World Health Organization. 26 April 2006. Archived from the original on 4 April 2011. Retrieved 4 April 2011.
- ^ "Chernobyl nuclear power plant site to be cleared by 2065". Kyiv Post. 3 January 2010. Archived from the original on 5 October 2012.