Hisashi Ouchi worked at the Japan Nuclear Fuel Conversion Company in Tokaimura, Japan. In 1999, after a fateful accident at Japan’s Tokaimura nuclear power plant Hisashi Ouchi lost most of his skin and began crying blood before his agony finally ended. When the incident at the Tokaimura power plant occurred, Hisashi was with two other guys, Masato Shinohara, 39, and Yutaka Yokokawa, 54. In Japan, at the Tokaimura thermal energy facility, Hisashi Ouchi worked as a lab specialist. His most well-known radiation accident exposed him to radiation at a level comparable to that of the nuclear weapon that was used to destroy Hiroshima. The book “A Slow Death: 83 Days of Radiation Illness” chronicles Hisashi Ouchi’s journey after the accident and the roughly 83 days he spent in the hospital after radiation exposure.

Birth Name

Hisashi Ouchi




An Operator and Technician at Nuclear Plan



Personal Life

Birthday / Date of Birth

Hisashi Ouchi was born in 1965, in Japan.


Hisashi Ouchi was died in 1999 at aged 35, in Japan.

Sun Sign



East Asian

He has Japanese ancestry.




His educational qualifications are unknown.

Family Details

  • Father – Unknown
  • Mother – Unknown
  • Siblings – Unknown

Marital Status



Girlfriend / Spouse

Hisashi Ouchi has dated –

Hisashi is married and the couple shares a young son together.

Physical Statistics


  • In feet – 5 feet 10 inches
  • In centimeters – 178 cm
  • In meters – 1.78 m


  • In Kilograms – 60 kg
  • In Pounds – 132 lbs

Body Build


Eye Color

Dark Brown

Hair Color

Dark Brown (Natural)

Shoe Size

He wears a size 11 (US) shoe.



Professional Statistics

Famous For

Hisashi became known as World’s Most Radioactive man, Japanese Radioactive and nuclear man. Ouchi is best known for the Accident at the 1999 Tokaimura Nuclear Power Plant. Scientists all over the world have always been very keen on the matter of radiation ever since it was discovered and used as a nuclear weapon.

Tokaimura Nuclear Incident

The Tokai nuclear plant earlier known as Japan Nuclear Plant was commissioned in the year 1988 and had the capacity to process up to 3 tonnes per year of uranium enriched up to 20% U-235. This type of Uranium was highly enriched uranium and it was a little higher than what is usually permissible. The procedure for nuclear fuel preparation for this plant was approved and it involved dissolving uranium oxide (U3O8) powder in nitric acid in a dissolution tank. Post completion of this process it becomes pure uranyl nitrate solution and is transferred to a storage column for mixing.

It is then transferred to a precipitation tank. It was this last process where Ouchi and his colleague Masato got affected by the radiation on that fateful day. The precipitation tank is surrounded by a water cooling jacket so that any extra heat generated by the exothermic chemical reaction is removed. The issue at this plant was that there was a major lapse in the overall process and there are three major problems that might have led to this accident.

The company had amended its standard operating procedure almost about three years back and did not seek permission from the regulatory authorities. Also, the operators were granted to ramp up the process by tipping the solution straight into the precipitation tank, which is against the protocol to be followed for the safety of everyone involved. There were no proper checks and balances in place for the amount tipped into the 100-liter precipitation tank. On September 30, 1999, Shinohara was pouring a uranyl nitrate solution into the mixing tank straight using a steel bucket.

Yokokawa was holding the funnel wherein liquid was poured by Shinohara. Eventually, Hisashi took over the task while Yokokawa went back to his desk. The reaction occurred in the mixing tank which led to an exothermic reaction. All the three men present there saw a blue flash of light and they immediately realized that there is something that went wrong terribly and tried to escape from the place as soon as possible. Ouchi went to the nearby changing room where he vomited and went unconscious.

83 Days in the Hospital

Hisashi Ouchi along with his two colleagues was initially admitted to the local hospital. They were later transferred to the National Institute of Radiological Sciences and finally, Hisashi Ouchi was relocated to the University of Tokyo Hospital. In this tragic incident, Hisashi Ouchi was right above the container when the accident happened, hence he absorbed most of the radiation. The radiation has completely destroyed his body.

He was immediately rushed to Tokyo Hospital for treatment. In the initial days, doctors noticed that he was doing somewhat fine and he was looking perfectly alright that even doctors were shocked. Hisashi Ouchi’s health started deteriorating and he suffered for 83 days. Finally, on 21st December 1999, he passed away due to multi-organ failure.

Some Lesser Known Facts About Hisashi Ouchi

  • Hisashi Born and brought up in Japan
  • In 1999, Ouchi was working at the Tokaimura nuclear power plant in Japan as a lab technician and he became popular ever since the radiation accident took place.
  • Ouchi was exposed to more radiation than a human being ever experienced before when the accident occurred at the Tokaimura Nuclear power plant. He fought for life for 83 days and succumbed to death because of multi-organ failure.
  • He along with his colleagues was mixing a batch of fuel at the JCO nuclear fuel processing plant. His colleague Yokokawa was sitting at a desk that was 13 feet away from the stainless steel container.
  • The uranium and exothermic chemical reaction that occurred in the process of generating energy from it led to a big blast that impacted 114 people in the plant.
  • Out of these 110 people have received lower doses and were unscathed by the accident whereas Hisashi Ouchi and his colleagues received high doses of radiation which resulted in 2 deaths. (Masato and Hisashi)


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