Elephant's Foot (Chernobyl)

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Artur Korneyev's photo of the Elephant's Foot, 1996 Chernobyl Elephant's Foot.jpg
Artur Korneyev's photo of the Elephant's Foot, 1996

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. It is named for its wrinkly appearance, evocative of the foot of an elephant.

Contents

Discovered in December of the year of the disaster, it is located in a maintenance corridor below the remains of Reactor No. 4, though the visible "elephant's foot" is only a part of a larger mass. It is still an extremely radioactive object, though the danger has decreased over time due to the decay of its radioactive components. [1] [2]

Origin

The Elephant's Foot is a mass of black corium with many layers, resembling tree bark and glass. It was formed during the Chernobyl disaster in April 1986 from a lava-like mixture of molten core material that had escaped the reactor enclosure, materials from the reactor itself, and various structural components of the plant such as concrete and metal. [3] The Foot was later discovered in December 1986. 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) below ground level. [4] [5] 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. [5]

Composition

The Elephant's Foot is a solidified corium glass composed primarily of silicon dioxide, with traces of dissolved uranium, titanium, zirconium, magnesium and graphite. [1] [2] [6] [7] Over time, zircon crystals have started to form slowly within the mass as it cools, and crystalline uranium dioxide dendrites are growing quickly and breaking down repeatedly. [3] Despite the distribution of uranium-bearing particles not being uniform, the radioactivity of the mass is evenly distributed. [3] The mass was quite dense and unyielding to efforts to collect samples for analysis via a drill mounted on a remote-controlled trolley, and armor-piercing rounds fired from an AK-47 assault rifle were necessary to break off usable chunks. [5] [1] [2] By June 1998, the outer layers had started turning to dust and the mass had started to crack, as the radioactive components were starting to disintegrate to a point where the structural integrity of the glass was failing. [3] In 2021, the mass was described as having a consistency similar to sand. [8]

Radioactivity

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 significantly, and in 1996, the Elephant's Foot was briefly 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]

The Elephant's Foot gives off radiation mainly in the form of alpha particles. As of 2015, measurements of a piece taken from the Elephant's Foot indicated radioactivity levels of roughly 2,500 Bq (.0675 µCi). [3] While alpha radiation is ordinarily unable to penetrate the skin, it is the most damaging form of radiation when radioactive particles are inhaled or ingested, which has renewed concerns as samples of material from the meltdown (including the Elephant's Foot) turn to dust and become aerosols. [8]

See also

Notes

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

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References

  1. 1 2 3 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. 1 2 3 4 5 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. 1 2 3 4 5 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.
  4. ↑ Hill, Kyle (4 December 2013). "Chernobyl's Hot Mess, 'the Elephant's Foot', Is Still Lethal". Nautilus . ISSN   2372-1766.
  5. 1 2 3 R. F. Mould (2000). Chernobyl Record: The Definitive History of the Chernobyl Catastrophe. CRC Press. p. 130. ISBN   9781420034622.
  6. ↑ 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.
  7. ↑ Ann Larabee (2000). Decade of Disaster (illustrated ed.). University of Illinois Press. p.  50. ISBN   9780252068201.
  8. 1 2 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 (27 April 2014). "Chernobyl: Capping a Catastrophe". The New York Times . Retrieved 12 January 2024.
  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.

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