The Most Radioactive Human In History

Short Introduction

Hisashi Ouchi was a nuclear power plant technician in Tokaimura, Japan, who suffered the highest level of radiation exposure of any human in history. In 1999, due to an obscene lack of safety measures and an abundance of fatal shortcuts, Ouchi and two other workers attempted to mix a new batch of fuel by hand. As a result, the room exploded with a blue flash and Ouchi was exposed to 17 sieverts of radiation. This left him with almost zero white blood cells, no immune system and caused his skin to melt. He passed away in December 1999 after 83 days of intense physical and mental suffering. The accident also caused the hospitalization of 610 people and the death of Ouchi's coworker, Masato Shinohara. The nuclear power plant in Tokaimura has not operated since the 2011 Tōhoku earthquake and tsunami.

How Hisashi Ouchi Became Most Radioactive Man In History

After a catastrophic nuclear accident at Japan’s Tokaimura nuclear power plant in 1999, Hisashi Ouchi, a 35-year-old nuclear power plant technician, became the most radioactive human in history. Ouchi was exposed to 17 sieverts of radiation, the highest recorded level for any human exposure, and suffered from a number of health complications, including skin melting and crying blood. His story reveals the dangerous negligence of the Japan Nuclear Fuel Conversion Co. (JCO) and the horrific consequences of radiation exposure.

Born in Japan in 1965, Hisashi Ouchi began working in the nuclear energy sector at a pivotal time for his country. With few natural resources and costly dependence on imported energy, Japan had begun developing nuclear power plants in the early 1960s and had opened its first commercial nuclear power plant four years before Ouchi’s birth. The Tokaimura power plant was located in the Ibaraki Prefecture northeast of Tokyo and employed one-third of the city’s population.

The accident occurred on the morning of Sept. 30, 1999, when Ouchi, his 29-year-old colleague Masato Shinohara, and their 54-year-old supervisor Yutaka Yokokawa attempted to mix a new batch of fuel without proper training or safety measures. Instead of using automatic pumps to mix 5.3 pounds of enriched uranium with nitric acid in a designated vessel, they used their hands to pour 35 pounds of it into steel buckets, causing the uranium to reach critical mass and the room to explode with a blue flash that confirmed a nuclear chain reaction had occurred.

Ouchi, Shinohara, and Yokokawa were all exposed to radiation, but Ouchi suffered the most. He was in immediate pain and had difficulty breathing, and by the time he arrived at the hospital, he had already vomited violently and fallen unconscious. His radiation burns covered his entire body, and his eyes were leaking blood. He had been exposed to more than seven sieverts of radiation, the fatal level, and had almost zero white blood cells and no immune response.

Doctors placed Ouchi in a special ward to prevent infection and assessed the damage to his internal organs. He underwent skin grafts and blood transfusions, and his sister donated stem cells to restore his blood-producing capabilities. Unfortunately, the stem cell transplants did not work, and Ouchi’s body could not rebuild itself due to his profuse radiation exposure. He cried for his mother and eventually suffered three heart attacks in one hour before his agony finally ended with a fourth cardiac arrest on December 21, 1999.

The Consequences of the Tokaimura Disaster

The aftermath of the Tokaimura disaster was devastating. The immediate evacuation of the nuclear power plant saw 310,000 villagers within six miles of the Tokai facility ordered to stay indoors for 24 hours. Over the next 10 days, 10,000 people were checked for radiation, with more than 600 people suffering minor levels. Ouchi’s colleague, Masato Shinohara, was exposed to 10 sieverts of radiation and spent seven months fighting for his life before succumbing to lung and liver failure. Yokokawa, the supervisor of the two deceased workers, suffered minor radiation sickness and was charged with negligence in October 2000. The company was ordered to pay $121 million to settle 6,875 compensation claims from affected locals.

The nuclear power plant in Tokaimura has not operated since the 2011 Tōhoku earthquake and tsunami. But the memory of Hisashi Ouchi’s suffering and death still looms large. Ouchi’s experience serves as a stark reminder of the dangerous consequences of radiation exposure and the importance of proper safety measures in the nuclear industry. Ouchi’s story is a tragic one, but his legacy can serve as a warning to future generations of the deadly risks associated with nuclear power.