Uploaded March 2026 | Updated September 2026, 3 weeks ago

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On September 30, 1999, the Tokaimura nuclear accident became the worst criticality accident in modern nuclear history. At a uranium processing facility in Japan, workers accidentally triggered a self-sustaining nuclear reaction while preparing fuel for an experimental reactor. One of the technicians, Hisashi Ouchi, received a massive radiation dose and spent 83 days in intensive medical care before his death. Over time, his story spread across the internet with misleading claims about what really happened. This [HALF-LIFE HISTORY] is the true story.

This video has been independently fact-checked by experts at the American Nuclear Society.

“A Slow Death 83 Days Of Radiation” by NHK TV Crew: archive.org/details/ASlowDeath83DaysOfRadiation/mode/2up

00:00 Intro
01:39 Critical Mistakes
06:20 Safe Geometry
10:22 Over-Reaction
13:26 “A Slow Death”
23:25 Human Factors Dominate
28:12 Patreon Supporters

SOURCES:
A Slow Death: 83 Days of Radiation Sickness. Translated by Maho Harada, Vertical, 2008. Internet Archive, archive.org/details/ASlowDeath83DaysOfRadiation/mode/2up. Accessed 10 Mar. 2026.

Tokaimura Nuclear Accident. Directed by NHK TV Crew, NHK (Japan Broadcasting Corporation), 2009. youtube.com/watch?v=ZWomuWd7-to

Davis, M. H. "The Japan Criticality Accident." National Republican, 2000, web.archive.org/web/20230429203013/nationalrep.org. Accessed 10 Mar. 2026. web.archive.org/web/20230429203013/http://nationalrep.org/2000/Japan%20Criticality%20Accident%20-%20Davis.pdf

International Atomic Energy Agency. Report on the Preliminary Fact Finding Mission Following the Accident at the Nuclear Fuel Processing Facility in Tokaimura, Japan. IAEA, 1999. IAEA Publications, www-pub.iaea.org/MTCD/publications/PDF/TOAC_web.pdf.

International Atomic Energy Agency. Report on the Preliminary Fact Finding Mission Following the Accident at the Nuclear Fuel Processing Facility in Tokaimura, Japan. IAEA, 1999. IAEA, www-ns.iaea.org/downloads/iec/tokaimura-report.pdf.

Ryan, Michael E. "The Tokaimura Accident." National Center for Case Study Teaching in Science, University at Buffalo, 25 June 2001. Internet Archive, web.archive.org/web/20190819091553/sciencecases.lib.buffalo.edu.

United States Nuclear Regulatory Commission. "Attachment 1: Review of the Tokai-mura Criticality Accident and Lessons Learned." SECY-00-0085, 12 Apr. 2000, nrc.gov/reading-rm/doc-collections/commission/secys/2000/secy2000-0085/attachment1.pdf.

Sokolov, Yuri. Human Errors Analysis and Safety Assessment in Industrial Facilities. Interim Report IR-05-003, International Institute for Applied Systems Analysis, Jan. 2005, pure.iiasa.ac.at/id/eprint/7832/1/IR-05-003.pdf.

Futami, Satoru. (2000). International Symposium on The Criticality Accident in Tokaimura: Medical Aspects of Radiation Emergency.

“The JCO Criticality Accident.” The Wall Street Journal, 30 Sept. 1999. Archive.ph, https://archive.ph/20230602144147/https://www.wsj.com/amp/articles/SB938689300261376572.

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