Elephant's Foot (Chernobyl)

The Elephant's Foot is the nickname given to a large mass of corium and other materials formed underneath the Chernobyl Nuclear Power Plant, near Pripyat, Ukraine, during the Chernobyl disaster of April 1986, notable for its extreme radioactivity. Discovered in December of that year, it is located in a maintenance corridor near the remains of Reactor No. 4. It is still an extremely radioactive object, though the danger has decreased over time due to the decay of its radioactive components.[1][2]

Artur Korneyev's photo of the Elephant's Foot, 1996

Origin
Main article: Chernobyl disaster

The Elephant's Foot is a mass of black corium with many layers, externally resembling tree bark and glass. It was formed during the Chernobyl disaster in April 1986 and discovered in December 1986. It is named for its wrinkly appearance, evocative of the foot of an elephant. It is one small part of a much larger mass that lies beneath Reactor No. 4 of the Chernobyl Nuclear Power Plant. The Elephant's Foot is located in Room 217/2, 15 metres (49 ft) to the southeast of the ruined reactor and 6 metres (20 ft) above ground level.[3][4] The material making up the Elephant's Foot had burnt through at least 2 metres (6.6 ft) of reinforced concrete, then flowed through pipes and fissures and down a hallway to reach its current location.[4]

Composition

The Elephant's Foot is composed primarily of silicon dioxide, with traces of uranium, titanium, zirconium, magnesium and graphite.[1][2][5][6] The mass is largely homogeneous,[7] though the depolymerized silicate glass contains occasional crystalline grains of zircon. These grains of zircon are not elongated, suggesting a moderate crystallization rate. While uranium dioxide dendrites grew quickly at high temperatures within the lava, the zircon began crystallization during slow cooling of the lava. Despite the distribution of uranium-bearing particles not being uniform, the radioactivity of the mass is evenly distributed.[7] The mass was quite dense and unyielding to a drill mounted on a remote-controlled trolley, but able to be damaged by armor-piercing rounds fired from an AK-47 assault rifle.[4][1][2] By June 1998, the outer layers had started turning to dust and the mass had started to crack.[7] In 2021, the mass was described as having a consistency similar to sand.[8]

Lethality

At the time of its discovery, about eight months after formation, radioactivity near the Elephant's Foot was approximately 8,000 to 10,000[9] roentgens, or 80 to 100 grays per hour,[2] delivering a 50/50 lethal dose of radiation (4.5 grays)[10] within five minutes.[2] Since that time the radiation intensity has declined enough that, in 1996, the Elephant's Foot was visited by the deputy director of the New Safe Confinement Project, Artur Korneyev,[lower-alpha 1] who took photographs using an automatic camera and a flashlight to illuminate the otherwise dark room.[12]

See also

Notes
  1. Korneyev was interviewed by The New York Times reporter Henry Fountain in 2014 in Slavutich, Ukraine, before his retirement.[11]

References
  1. Higginbotham, Adam (2019). Midnight in Chernobyl: The Untold Story of the World's Greatest Nuclear Disaster. Random House. p. 340. ISBN 9781473540828. The substance proved too hard for a drill mounted on a motorized trolley, ... Finally, a police marksman arrived and shot a fragment of the surface away with a rifle. The sample revealed that the Elephant's Foot was a solidified mass of silicon dioxide, titanium, zirconium, magnesium, and uranium ...
  2. United States Foreign Broadcast Information Service, ed. (1989). Daily Report: Soviet Union. The Service. p. 133. The radiation level near it was approximately 8,000 roentgens per hour in 1986. Even five minutes spent near the "foot" would have killed a man ... the substance failed to yield to a drill mounted on a special remote-controlled truck ... A skilled marksman ... fired armor-piercing bullets into it ... Analysis of the fragments obtained in this way showed that they consisted of 70–90% silicon dioxide (fused sand), 2–10% fuel particles, and, in addition, contained graphite (hence the black color), metal alloys, and so on ...
  3. Hill, Kyle (4 December 2013). "Chernobyl's Hot Mess, 'the Elephant's Foot', Is Still Lethal". Nautilus. ISSN 2372-1766.
  4. R. F. Mould (2000). Chernobyl Record: The Definitive History of the Chernobyl Catastrophe. CRC Press. p. 130. ISBN 9781420034622.
  5. Jaromir Kolejka, ed. (2002). Role of GIS in Lifting the Cloud Off Chernobyl. NATO Science: Earth and environmental sciences. Vol. 10 (illustrated ed.). Springer Science & Business Media. p. 72. ISBN 9781402007682.
  6. Ann Larabee (2000). Decade of Disaster (illustrated ed.). University of Illinois Press. p. 50. ISBN 9780252068201.
  7. Vlasova, Irina; Shiryaev, Andrey; Ogorodnikov, Boris; Burakov, Boris; Dolgopolova, Ekaterina; Senin, Roman; Averin, Alexey; Zubavichus, Yan; Kalmykov, Stepan (2015). "Radioactivity distribution in fuel-containing materials (Chernobyl "lava") and aerosols from the Chernobyl "Shelter"". Radiation Measurements. 83: 20–25. Bibcode:2015RadM...83...20V. doi:10.1016/j.radmeas.2015.06.005. ISSN 1350-4487.
  8. Stone, Richard (5 May 2021). "'It's like the embers in a barbecue pit.' Nuclear reactions are smoldering again at Chernobyl". Science. Archived from the original on 2021-05-12. Retrieved 12 May 2021.
  9. "The Elephant's Foot of the Chernobyl disaster, 1986 - Rare Historical Photos". Rare Historical Photos. 2014-07-02. Retrieved 2022-04-29.
  10. "Lethal Dose (LD)". US Nuclear Regulatory Commission. 21 March 2019. Retrieved 21 March 2019.
  11. Fountain, Henry; Daniels, William (27 April 2014). "Chernobyl: Capping a Catastrophe". The New York Times. Retrieved 21 March 2019.
  12. Goldenberg, Daniel (24 January 2016). "The Famous Photo of Chernobyl's Most Dangerous Radioactive Material Was a Selfie". Atlas Obscura. Retrieved 21 March 2019.

51.3892°N 30.09833°E / 51.3892; 30.09833

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