Humanity's uranium-238 inventory: A significant and enduring gamma-radiation liability

1. US Atomic Energy Commission. (1974). Environmental survey of the reprocessing and waste management portions of the LWR fuel cycle. (WASH-1248). Directorate of Licensing. (NUREG-0116). Available at https://www.nrc.gov/docs/ML1409/ML14091A203.pdf. US Atomic Energy Commission 1974 Environmental survey of the reprocessing and waste management portions of the LWR fuel cycle (WASH-1248). Directorate of Licensing. (NUREG-0116). Available at https://www.nrc.gov/docs/ML1409/ML14091A203.pdf. Search in Google Scholar

2. Svensk Kärnbränslehantering AB. (1999). SR-97 post-closure safety: Deep repository for spent nuclear fuel. Stockholm, Sweden: SKB. (Technical Report TR-99-06). Available at https://www.skb.com/publication/2488114/TR-99-06_vol1.pdf. Svensk Kärnbränslehantering AB 1999 SR-97 post-closure safety: Deep repository for spent nuclear fuel Stockholm, Sweden SKB (Technical Report TR-99-06). Available at https://www.skb.com/publication/2488114/TR-99-06_vol1.pdf. Search in Google Scholar

3. United Nations Scientific Committee on the Effects of Atomic Radiation. (2008). Sources and effects of ionizing radiation. UNSCEAR Report to the General Assembly with Scientific Annexes. (Vol. 1). United Nations. Available at https://www.unscear.org/unscear/en/publications/2008_1.html. United Nations Scientific Committee on the Effects of Atomic Radiation 2008 Sources and effects of ionizing radiation. UNSCEAR Report to the General Assembly with Scientific Annexes (Vol. 1). United Nations. Available at https://www.unscear.org/unscear/en/publications/2008_1.html. Search in Google Scholar

4. United Nations Scientific Committee on the Effects of Atomic Radiation. (2016). Sources and effects of ionizing radiation. Report to the General Assembly – Annex D. United Nations. Available at https://www.unscear.org/unscear/uploads/documents/publications/UNSCEAR_2016_Annex-D-CORR.pdf. United Nations Scientific Committee on the Effects of Atomic Radiation 2016 Sources and effects of ionizing radiation. Report to the General Assembly – Annex D United Nations. Available at https://www.unscear.org/unscear/uploads/documents/publications/UNSCEAR_2016_Annex-D-CORR.pdf. Search in Google Scholar

5. International Atomic Energy Agency. (2023). The environmental behaviour of uranium. Vienna: IAEA. (Technical Report no. 488). Available at https://www.iaea.org/publications/14688/the-environmental-behaviour-of-uranium. International Atomic Energy Agency 2023 The environmental behaviour of uranium Vienna IAEA (Technical Report no. 488). Available at https://www.iaea.org/publications/14688/the-environmental-behaviour-of-uranium. Search in Google Scholar

6. United Nations Scientific Committee on the Effects of Atomic Radiation. (2000). Report to the United Nations Scientific Committee on the Effects of Atomic Radiation. (Suppl. no. 46). United Nations. United Nations Scientific Committee on the Effects of Atomic Radiation 2000 Report to the United Nations Scientific Committee on the Effects of Atomic Radiation (Suppl. no. 46). United Nations. Search in Google Scholar

7. Burns, P. C., Ewing, R. C., & Navrotsky, A. (2012). Nuclear fuel in a reactor accident. Science, 335(6073), 1184–1188. DOI: 10.1126/science.1211285. BurnsP. C. EwingR. C. NavrotskyA. 2012 Nuclear fuel in a reactor accident Science 335 6073 1184 1188 10.1126/science.1211285 Open DOISearch in Google Scholar

8. Office of Radiation Programs. (1980). Draft environmental impact statement for remedial action standards for inactive uranium processing sites. Washington, D.C.: US Environmental Protection Agency. Available at https://nepis.epa.gov/Exe/ZyPDF.cgi/20015ZDF.PDF?Dockey=20015ZDF.PDF. Office of Radiation Programs 1980 Draft environmental impact statement for remedial action standards for inactive uranium processing sites Washington, D.C. US Environmental Protection Agency Available at https://nepis.epa.gov/Exe/ZyPDF.cgi/20015ZDF.PDF?Dockey=20015ZDF.PDF. Search in Google Scholar

9. International Commission on Radiological Protection. (2007). The 2007 Recommendations of the International Commission on Radiological Protection. ICRP Publication no. 103. Ann. ICRP, 37(2/4), 1–332. Available at https://www.icrp.org/publication.asp?id=ICRP%20Publication%20103. International Commission on Radiological Protection 2007 The 2007 Recommendations of the International Commission on Radiological Protection. ICRP Publication no. 103 Ann. ICRP 37 2/4 1 332 Available at https://www.icrp.org/publication.asp?id=ICRP%20Publication%20103. Search in Google Scholar

10. Pescatore, C. (2024). Beyond one million years: The intrinsic radiation hazard of high-level nuclear wastes. Nukleonika, 69(4), 215–224. DOI: 10.2478/nuka-2024-0029. PescatoreC. 2024 Beyond one million years: The intrinsic radiation hazard of high-level nuclear wastes Nukleonika 69 4 215 224 10.2478/nuka-2024-0029 Open DOISearch in Google Scholar

11. International Atomic Energy Agency. (n.d.). Depleted uranium. Vienna: IAEA. Available at https://www.iaea.org/topics/spent-fuel-management/depleted-uranium. International Atomic Energy Agency (n.d.). Depleted uranium Vienna IAEA Available at https://www.iaea.org/topics/spent-fuel-management/depleted-uranium. Search in Google Scholar

12. International Atomic Energy Agency. (1997). Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management. Vienna: IAEA. Available at https://www.iaea.org/topics/nuclear-safety-conventions/joint-convention-safety-spent-fuel-management-and-safety-radioactive-waste. International Atomic Energy Agency 1997 Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management Vienna IAEA Available at https://www.iaea.org/topics/nuclear-safety-conventions/joint-convention-safety-spent-fuel-management-and-safety-radioactive-waste. Search in Google Scholar

13. Nuclear Energy Agency. (2001). Management of depleted uranium. NEA. Available at https://www.oecdnea.org/upload/docs/application/pdf/2019-12/3035-management-depleted-uranium.pdf. Nuclear Energy Agency 2001 Management of depleted uranium NEA. Available at https://www.oecdnea.org/upload/docs/application/pdf/2019-12/3035-management-depleted-uranium.pdf. Search in Google Scholar

14. US Nuclear Regulatory Commission. (2023). Background information on depleted uranium. USNRC. Available at https://www.nrc.gov/waste/llw-disposal/decision-support/uw-streams/bg-info-du.html#current. US Nuclear Regulatory Commission 2023 Background information on depleted uranium USNRC. Available at https://www.nrc.gov/waste/llw-disposal/decision-support/uw-streams/bg-info-du.html#current. Search in Google Scholar

15. Sutherland, J. K. (2008). The nuclear reactor closed cycle. EFN – Environmentalists for NuclearTM. Available at https://www.ecolo.org/documents/documents_in_english/uran-closed-cycle-sutherl.pdf. SutherlandJ. K. 2008 The nuclear reactor closed cycle EFN – Environmentalists for NuclearTM. Available at https://www.ecolo.org/documents/documents_in_english/uran-closed-cycle-sutherl.pdf. Search in Google Scholar

16. United Nations Scientific Committee on the Effects of Atomic Radiation. (2024). Sources and effects of ionizing radiation. UNSCEAR 2024 Report to the General Assembly with Scientific Annexes. United Nations. United Nations Scientific Committee on the Effects of Atomic Radiation 2024 Sources and effects of ionizing radiation. UNSCEAR 2024 Report to the General Assembly with Scientific Annexes United Nations Search in Google Scholar

17. International Atomic Energy Agency. (2004). The long-term stabilization of uranium mill tailings. Vienna: IAEA. (TECDOC-1403). Available at https://www.iaea.org/publications/6670/the-long-terms-tabilization-of-uranium-mill-tailings. International Atomic Energy Agency 2004 The long-term stabilization of uranium mill tailings Vienna IAEA. (TECDOC-1403) Available at https://www.iaea.org/publications/6670/the-long-terms-tabilization-of-uranium-mill-tailings. Search in Google Scholar

18. Nuclear Energy Agency. (2014). Managing environmental and health impacts of uranium mining. Paris: OECD. (NEA no. 7062). Available at https://www.oecd-nea.org/jcms/pl_14766/managing-environmental-and-health-impacts-of-uranium-mining?details=true. Nuclear Energy Agency 2014 Managing environmental and health impacts of uranium mining Paris OECD (NEA no. 7062). Available at https://www.oecd-nea.org/jcms/pl_14766/managing-environmental-and-health-impacts-of-uranium-mining?details=true. Search in Google Scholar

19. United Nations Environment Programme. (2001). Depleted uranium in Kosovo: Post-conflict environmental assessment. UNEP. Available at https://www.unep.org/resources/report/depleted-uranium-kosovo-post-conflict-environmental-assessment. United Nations Environment Programme 2001 Depleted uranium in Kosovo: Post-conflict environmental assessment UNEP. Available at https://www.unep.org/resources/report/depleted-uranium-kosovo-post-conflict-environmental-assessment. Search in Google Scholar

20. United Nations Environment Programme. (2002). Depleted uranium in Serbia and Montenegro: Post-conflict environmental assessment. UNEP. Available at: https://www.unep.org/topics/disasters-and-conflicts/response-and-recovery/post-crisis-environmental-assessment/depleted. United Nations Environment Programme 2002 Depleted uranium in Serbia and Montenegro: Post-conflict environmental assessment UNEP. Available at: https://www.unep.org/topics/disasters-and-conflicts/response-and-recovery/post-crisis-environmental-assessment/depleted. Search in Google Scholar

21. International Atomic Energy Agency. (2003). Radiological conditions in areas of Kuwait with residues of depleted uranium. Vienna: IAEA. Available at https://www.iaea.org/publications/6880/radiological-conditions-in-areas-of-kuwait-with-residues-of-depleted-uranium. International Atomic Energy Agency 2003 Radiological conditions in areas of Kuwait with residues of depleted uranium Vienna IAEA Available at https://www.iaea.org/publications/6880/radiological-conditions-in-areas-of-kuwait-with-residues-of-depleted-uranium. Search in Google Scholar

22. International Coalition to Ban Uranium Weapons. (2007). Precaution in practice. ICBUW. Available at https://paxforpeace.nl/wp-content/uploads/sites/2/2020/11/986_icbuw-precaution-in-practice-1.pdf. International Coalition to Ban Uranium Weapons 2007 Precaution in practice ICBUW. Available at https://paxforpeace.nl/wp-content/uploads/sites/2/2020/11/986_icbuw-precaution-in-practice-1.pdf. Search in Google Scholar

23. Duraković, A. (2003). Undiagnosed illnesses and radioactive warfare. Croatian Medical Journal, 44(5), 520–532. Available at https://pubmed.ncbi.nlm.nih.gov/14515407/. DurakovićA. 2003 Undiagnosed illnesses and radioactive warfare Croatian Medical Journal 44 5 520 532 Available at https://pubmed.ncbi.nlm.nih.gov/14515407/. Search in Google Scholar

24. Chu, M. S. Y., & Bernard, E. A. (1991). Waste inventory and preliminary source term model for the greater confinement disposal site at the Nevada test site. Albuquerque: Sandia National Laboratories. (SAND-91-0170). Available at https://www.osti.gov/servlets/purl/613994-jGolcx/webviewable/. ChuM. S. Y. BernardE. A. 1991 Waste inventory and preliminary source term model for the greater confinement disposal site at the Nevada test site Albuquerque Sandia National Laboratories (SAND-91-0170). Available at https://www.osti.gov/servlets/purl/613994-jGolcx/webviewable/. Search in Google Scholar

25. US Department of Energy Nevada National Security Site. (September 2022). Environmental report summary 2021. Nevada National NNSS. (DOE/NV/03624—1517). Available at https://nnss.gov/wp-content/uploads/2023/04/Nevada-National-Security-Site-Environmental-Report-2021-Summary-Final.pdf. US Department of Energy Nevada National Security Site September 2022 Environmental report summary 2021 Nevada National NNSS. (DOE/NV/03624—1517). Available at https://nnss.gov/wp-content/uploads/2023/04/Nevada-National-Security-Site-Environmental-Report-2021-Summary-Final.pdf. Search in Google Scholar

26. International Atomic Energy Agency. (2009). Radiological conditions at the Semipalatinsk test site, Kazakhstan: Preliminary assessment and recommendations for further study. Vienna: IAEA. Available at https://www.iaea.org/publications/4741/radiological-conditions-at-the-semipalatinsk-test-site-kazakhstan. International Atomic Energy Agency 2009 Radiological conditions at the Semipalatinsk test site, Kazakhstan: Preliminary assessment and recommendations for further study Vienna IAEA Available at https://www.iaea.org/publications/4741/radiological-conditions-at-the-semipalatinsk-test-site-kazakhstan. Search in Google Scholar

27. International Atomic Energy Agency. (2004). Environmental contamination from uranium production facilities and their remediation. Vienna: IAEA. Available at https://www-pub.iaea.org/MTCD/Publications/PDF/Pub1228_web.pdf. International Atomic Energy Agency 2004 Environmental contamination from uranium production facilities and their remediation Vienna IAEA Available at https://www-pub.iaea.org/MTCD/Publications/PDF/Pub1228_web.pdf. Search in Google Scholar

28. International Atomic Energy Agency. (2012). Spent fuel performance assessment and research – Final report of a Coordinated Research Project (SPARII). Vienna: IAEA. (TECDOC-1680). Available at https://www-pub.iaea.org/MTCD/Publications/PDF/TE_1680_web.pdf. International Atomic Energy Agency 2012 Spent fuel performance assessment and research – Final report of a Coordinated Research Project (SPARII) Vienna IAEA (TECDOC-1680). Available at https://www-pub.iaea.org/MTCD/Publications/PDF/TE_1680_web.pdf. Search in Google Scholar

29. Khattak, M. A., Mahadi, M. Z. B., & Bahri, N. B. S. (2017). A review of nuclear spent fuel storage facilities. Journal of Advanced Research in Science, 29(1), 1–19. Available at https://www.akademiabaru.com/doc/ARSRV29_N1_P1_19.pdf. KhattakM. A. MahadiM. Z. B. BahriN. B. S. 2017 A review of nuclear spent fuel storage facilities Journal of Advanced Research in Science 29 1 1 19 Available at https://www.akademiabaru.com/doc/ARSRV29_N1_P1_19.pdf. Search in Google Scholar

30. Bevard, B., Mertyurek, U., Belles, R., & Scaglione, J. M. (2015). BWR Spent Nuclear Fuel Integrity Research and Development Survey for UKABWR Spent Fuel Interim Storage. OSTI. Available at https://www.osti.gov/servlets/purl/1234354. BevardB. MertyurekU. BellesR. ScaglioneJ. M. 2015 BWR Spent Nuclear Fuel Integrity Research and Development Survey for UKABWR Spent Fuel Interim Storage OSTI. Available at https://www.osti.gov/servlets/purl/1234354. Search in Google Scholar

31. Interagency Review Group on Nuclear Waste Management. (March 1979). Report to the President by the Interagency Review Group on Nuclear Waste Management. (DOE Report TID-29442/UC-70). Available at https://curie.pnnl.gov/system/files/Interagency_Review_Group_Report_MOL.19980625.0169.pdf. Interagency Review Group on Nuclear Waste Management March 1979 Report to the President by the Interagency Review Group on Nuclear Waste Management (DOE Report TID-29442/UC-70). Available at https://curie.pnnl.gov/system/files/Interagency_Review_Group_Report_MOL.19980625.0169.pdf. Search in Google Scholar

32. Linnaeus University. (2019). Workshop on Information and Memory for Future Decision Making: Radioactive Waste and Beyond, Stockholm, May 2019. Available at https://lnu.se/en/research/research-groups/unesco-chair-on-heritage-futures/information-memory/. Linnaeus University 2019 Workshop on Information and Memory for Future Decision Making: Radioactive Waste and Beyond, Stockholm, May 2019 Available at https://lnu.se/en/research/research-groups/unesco-chair-on-heritage-futures/information-memory/. Search in Google Scholar

33. Pescatore, C., & Palm, J. (2020). Preserving memory and information on heritage and on unwanted legacies – new tools for identifying sustainable strategies to prepare and support decision making by future generations. SCEaR Newsletter, 1, 4–14. Available at https://literaryartisticarchives-ica.org/wp-content/uploads/2020/07/scearnewsletter2020-1june30.pdf. PescatoreC. PalmJ. 2020 Preserving memory and information on heritage and on unwanted legacies – new tools for identifying sustainable strategies to prepare and support decision making by future generations SCEaR Newsletter 1 4 14 Available at https://literaryartisticarchives-ica.org/wp-content/uploads/2020/07/scearnewsletter2020-1june30.pdf. Search in Google Scholar

34. International Atomic Energy Agency, & Nuclear Energy Agency. (2022). Uranium 2022: Resources, production and demand (Red Book). Paris: OECD Publishing. Available at https://www.oecd-nea.org/jcms/pl_79960/uranium-2022-resources-production-and-demand?details=true. International Atomic Energy Agency, & Nuclear Energy Agency 2022 Uranium 2022: Resources, production and demand (Red Book) Paris OECD Publishing Available at https://www.oecd-nea.org/jcms/pl_79960/uranium-2022-resources-production-and-demand?details=true. Search in Google Scholar

35. International Atomic Energy Agency. (2022). Status and trends in spent fuel and radioactive waste management. Rev. 1. (Nuclear Energy Series no. NW-T-1.14). Vienna: IAEA. Available at https://www.iaea.org/publications/14739/status-and-trends-in-spent-fuel-and-radioactive-waste-management. International Atomic Energy Agency 2022 Status and trends in spent fuel and radioactive waste management. Rev. 1 (Nuclear Energy Series no. NW-T-1.14). Vienna: IAEA. Available at https://www.iaea.org/publications/14739/status-and-trends-in-spent-fuel-and-radioactive-waste-management. Search in Google Scholar

36. Hedin, A. (1997). How dangerous is spent fuel? Swedish Spent Fuel Management Company. (SKBTR-97-13). Available at https://www.skb.com/publication/13607. HedinA. 1997 How dangerous is spent fuel? Swedish Spent Fuel Management Company (SKBTR-97-13). Available at https://www.skb.com/publication/13607. Search in Google Scholar

37. Orano Mining. (n.d.). Après-mines France. https://www.orano.group/fr/l-expertise-nucleaire/de-lexploration-au-recyclage/producteur-d-uranium-dereference/apres-mines-france-orano-mining#. Orano Mining (n.d.). Après-mines France https://www.orano.group/fr/l-expertise-nucleaire/de-lexploration-au-recyclage/producteur-d-uranium-dereference/apres-mines-france-orano-mining#. Search in Google Scholar

38. Ballini, M., Chautard, C., Nos, J., & Phrommavanh, V. (2020). A multi-scalar study of the long-term reactivity of uranium mill tailings from Bellezane site (France). J. Environ. Manage., 271, 111050. Available at https://www.sciencedirect.com/science/article/pii/S0265931X19307647. BalliniM. ChautardC. NosJ. PhrommavanhV. 2020 A multi-scalar study of the long-term reactivity of uranium mill tailings from Bellezane site (France) J. Environ. Manage 271 111050 Available at https://www.sciencedirect.com/science/article/pii/S0265931X19307647. Search in Google Scholar

39. Djenbaev, B., Zholbolduev, B., Zhulmaliev, T., & Voisekhovich, O. (2015). Radioecological assessment of the uranium tailings in Tuyuk-Suu (Kyrgyzstan). Journal of Geological Sciences, 3(2), 89–97. Available at https://pdfs.semanticscholar.org/2dc1/555576dcded0097b521ee07ecb4f8c35c1bb.pdf. DjenbaevB. ZholbolduevB. ZhulmalievT. VoisekhovichO. 2015 Radioecological assessment of the uranium tailings in Tuyuk-Suu (Kyrgyzstan) Journal of Geological Sciences 3 2 89 97 Available at https://pdfs.semanticscholar.org/2dc1/555576dcded0097b521ee07ecb4f8c35c1bb.pdf. Search in Google Scholar

40. Carvalho, F. P., Madruga, M. J., Reis, M. C., & Alves, J. G. (2007). Radioactivity in the environment around past radium and uranium mining sites of Portugal. J. Environ. Radioact., 96(1/3), 39–46. Available at https://www.sciencedirect.com/science/article/pii/S0265931X07000665. CarvalhoF. P. MadrugaM. J. ReisM. C. AlvesJ. G. 2007 Radioactivity in the environment around past radium and uranium mining sites of Portugal J. Environ. Radioact 96 1/3 39 46 Available at https://www.sciencedirect.com/science/article/pii/S0265931X07000665. Search in Google Scholar

41. Lavrova, T., & Voitsekhovych, O. (2013). Radioecological assessment and remediation planning at the former uranium milling facilities at the Pridnieprovsky Chemical Plant in Ukraine. J. Environ. Radioact., 113, 35–43. Available at https://www.researchgate.net/publication/230741377_Radioecological_assessment_and_remediation_planning_at_the_former_uranium_milling_facilities_at_the_Pridnieprovsky_Chemical_Plant_in_Ukraine. LavrovaT. VoitsekhovychO. 2013 Radioecological assessment and remediation planning at the former uranium milling facilities at the Pridnieprovsky Chemical Plant in Ukraine J. Environ. Radioact 113 35 43 Available at https://www.researchgate.net/publication/230741377_Radioecological_assessment_and_remediation_planning_at_the_former_uranium_milling_facilities_at_the_Pridnieprovsky_Chemical_Plant_in_Ukraine. Search in Google Scholar

42. Wang, J., Liu, J., Chen, Y., Song, G., Chen, D., & Xiao, T. (2016). Technologically elevated natural radioactivity and assessment of dose to workers around a granitic uranium deposit area, China. J. Radioanal. Nucl. Chem., 309(3), 1331–1339. Available at https://link.springer.com/article/10.1007/s10967-016-4809-2. WangJ. LiuJ. ChenY. SongG. ChenD. XiaoT. 2016 Technologically elevated natural radioactivity and assessment of dose to workers around a granitic uranium deposit area, China J. Radioanal. Nucl. Chem 309 3 1331 1339 Available at https://link.springer.com/article/10.1007/s10967-016-4809-2. Search in Google Scholar

43. Carvalho, F. P. (2018). Uranium mining legacy and radiation protection. Radiation & Applications, 3(2), 130–134. Available at https://www.researchgate.net/publication/324157440_Uranium_Mining_Legacy_and_Radiation_Protection. CarvalhoF. P. 2018 Uranium mining legacy and radiation protection Radiation & Applications 3 2 130 134 Available at https://www.researchgate.net/publication/324157440_Uranium_Mining_Legacy_and_Radiation_Protection. Search in Google Scholar

44. Haywood, F. F., Christian, D. J., Ellis, B. S., Hubbard, H. M. Jr., Lorenzo, D., & Shinpaugh, W. H. (June 1980). Radiological survey of the inactive uraniummill tailings at Ambrosia Lake, New Mexico. Oak Ridge: Oak Ridge National Laboratory. (ORNL-5458). Available at https://doi.org/10.2172/5293415. HaywoodF. F. ChristianD. J. EllisB. S. HubbardH. M.Jr. LorenzoD. ShinpaughW. H. June 1980 Radiological survey of the inactive uraniummill tailings at Ambrosia Lake, New Mexico Oak Ridge Oak Ridge National Laboratory (ORNL-5458). Available at https://doi.org/10.2172/5293415. Search in Google Scholar

45. Swift, J., Hardin, J. M., & Calley, H. W. (January 1976). Potential radiological impact of airborne releases and direct gamma radiation to individuals living near inactive mill tailings piles. U.S. Environmental Protection Agency, Office of Radiation Programs. (EPA-520/1-76-001). Available at https://nepis.epa.gov/Exe/ZyPDF.cgi/910121O5.PDF?Dockey=910121O5.PDF. SwiftJ. HardinJ. M. CalleyH. W. January 1976 Potential radiological impact of airborne releases and direct gamma radiation to individuals living near inactive mill tailings piles U.S. Environmental Protection Agency, Office of Radiation Programs (EPA-520/1-76-001). Available at https://nepis.epa.gov/Exe/ZyPDF.cgi/910121O5.PDF?Dockey=910121O5.PDF. Search in Google Scholar

46. International Atomic Energy Agency. (2018). Meet Oklo, the Earth's two-billion-year-old only known natural nuclear reactor. Available at https://www.iaea.org/newscenter/news/meet-oklo-the-earths-two-billion-year-old-only-known-natural-nuclear-reactor. International Atomic Energy Agency 2018 Meet Oklo, the Earth's two-billion-year-old only known natural nuclear reactor Available at https://www.iaea.org/newscenter/news/meet-oklo-the-earths-two-billion-year-old-only-known-natural-nuclear-reactor. Search in Google Scholar