Tokaimura Nuclear Disaster
Howard Jiang
Description of what happened
- Occurred on September 30, 1999
- When a fission reaction happening in the plant reached its point of criticality, the nuclear fission chain began to emit intense gamma and neutron radiation
- Almost immediately, a mass evacuation occurred, and shielding/other cautionary measures were taken to prevent the spread of the radiation.
Why did it occur?
- This was the plant's first batch of fuel for the specific reactor in three years
- Qualifications and training requirements were not met by the workers.
- The uranium was already mixed within the solution, making it difficult for the reaction to be stopped.
How can we prevent/protect?
- Make sure workers at nuclear power plants are well trained
- Have the ability to stop the reaction in case of another accident
- Overall, relatively good protection practices and cautionary measures were taken as/after the accident occurred.
Effects (ecological and human)
- Two of three workers at the plant who were exposed to high doses of radiation died
- Increase in radioactive substances found in surrounding wildlife and soil, but not signficant amounts
- Local radiation levels returned to normal within weeks
Hisashi Ouchi (cont.)
- Possibly exposed to the highest radiation ever by any human
- Kept alive for 83 days until he died
- The radiation caused his chromosomes to be destroyed and also caused his white blood cell count to almost reach zero.
Works Cited
Dudzinski, Ryan. The Tokaimura Criticality Accident of 1999. Stanford University, 1 Mar. 2017, large.stanford.edu/courses/2017/ph241/dudzinski1/.
“Hisashi Ouchi, the Victim of Beyond Fatal Radiation Kept Alive for 83 Days Against His Will.” Unbelievable Facts, 3 Dec. 2016, www.unbelievable-facts.com/2016/12/hisashi-ouchi.html.
“Tokaimura Criticality Accident 1999.” World Nuclear Association, World Nuclear Association, Oct. 2013, www.world-nuclear.org/information-library/safety-and-security/safety-of-plants/tokaimura-criticality-accident.aspx.