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JCO Criticality Accident

We have compiled the following materials on the JCO criticality incident that occurred at Tokai Village on 30 September 1999. The term 'criticality accident' here refers to an accidentally induced nuclear chain reaction - potentially the most dangerous type of accident that could occur. Readers might also be interested to see our Nuclear Safety page to get a broader picture of how unsafe and untrustworthy the nuclear industry really is.

A selection of articles from our newsletter

Chronological Reports

JCO Chronology

JCO Publications

A selection of articles from our newsletter

An accident not to be forgotten: 10 Years have passed since the JCO Criticality Accident (NIT 132 September/October 2009)

JCO Criticality Accident: Book Review (NIT 128, Jan./Feb. 2009)
A Slow Death: 83 Days of Radiation Sickness is a translation of a Japanese book based on an NHK television documentary.

We Oppose Removal and Dismantling of Tokai Reactor (NIT 103 Nov./Dec. 2004)

JCO Criticality Accident: Five Years On (NIT 102 Sep/Oct 2004)

JCO 4th Anniversary (NIT 97 Sep/Oct 2003)

Ruling on JCO Accident (NIT 94 March/April 2003)

JCO Criticality Accident Three Years on: Questions Still Unanswered (NIT 91 Sep/Oct 2002)

Findings on JCO Accident (NIT 78 Jul/Aug 2000)

JCO Victims' Group (NIT 77 May/June 2000)

STA's dose evaluation of JCO accident (NIT 76 March/April 2000)

JCO Criticality Accident (NIT 75 Jan/Feb 2000)

JCO Criticality Accident: How Many Lessons will it Take? (NIT 74 Nov/Dec 1999)

See also back issues of our bi-monthly publication, Nuke Info Tokyo, for more articles.

Chronological Reports

Report[40] Exposure Dose According to STA's Report Released on 13 October, 2000
Report [39] Few Safety Improvements Seen Since JCO Accident
Report [38] STA Adds 229 to Its List of Exposed People Due to JCO Accident
Report [37] Six JCO Employees Arrested
Report [36] A Visit to Tokai-mura a Year After the JCO Accident
Report [35] Sep.30 2000 Japanese Nuclear Industry in the Aftermath of the JCO Accident
Report [34]Criticality Accident at Tokai-mura 1mg of uranium that shattered Japan's nuclear myth - Speech in Bonn
Report [33] Inquiry into the Responsibility of the Former PNC and STA
Report [32] Rushed Interim Report Plays Down the Accident
Report [31] Second Death from JCO Criticality Accident
Report [30] JCO to Lose Its License
Report [29] The Latest Data of Exposure
Report [28]Survivors of Tokai Victim to Receive Compensation!
Report [27]Anti-Nuke Candidate Elected At Tokai Village!!
Report [26]Rushed Final Report With No Substance
Report [25] In Condolence of the Criticality Accident Victim
Report [24] Uranium Solution in the Hose Collected:Missing Solution Found?
Report [23] CNIC Responds to IAEA Report
Report [22] Radioactive materials detected[2]
Report [21] CNIC Sets Up an Independent Investigation Committee on JCO Criticality Accident
Report [20] JCO accident further delays Japan's nuclear power plans
Report [19] Accident Investigation Committee Puts Out an Interim Report
Report [18] Information From Accident Investigation Committee Won't Be Made Public!
Report [17] DNA Damage Found in Eight People by Secretive Analysis
Report [16] STA Inspects Conversion Building on October 26th and 27th
Report [15] Calculation On The Scale Of The JCO Criticality Accident
Report [14] Department of Energy (DOE) members sent from America to check out JCO
Report [13] 20 Liters of Uranium Solution in the Precipitation Basin Missing!
Report [12] Experts Sent to Vienna to Report on the Accident
Report [11] Demand to STA & NSC
Report [10] Sample of the solution in the precipitation tank taken on Oct. 20
Report [9] IAEA inspectors
Report [8] Facility inspection
Report [7] Contaminated hose
Report [6] The second "Accident Investigation Committee"
Report [5] Radiation Was Indeed Leaking
Report [4] Radioactive materials detected[1]
Report [3] Worst Ever Nuclear Accident in Japanese History Was an Accident Waiting to Happen
Report [2] Conduct a thorough research and release complete data
Report [1] Accident is not over
CNIC's Statement on the Criticality Accident at  Tokai
Serious nuclear accident at Tokai - initial response 1
Worst Ever Accident Within Japan at Tokai, Ibaraki - initial response 2

Also see back issues of our bi-monthly publication, Nuke Information Tokyo, for more articles.


Citizens' Nuclear Information Center
Akebonobashi Co-op 2F-B, 8-5 Sumiyoshi-cho,
Shinjuku-ku, Tokyo, 162-0065, Japan