Medical history of Yutaka Yokokawa

Yutaka Yokokawa was the supervisor of both Ouchi and Shinohara. Commonly in medical documents, he is referred to as Patient C. In one document, I found him as Patient Y. but it is not common. Yokokawa was at his desk during the criticality however remained back in an attempt to contact radiation safety personnel. He was exposed to 2Gy. Other information about him is that he was a smoker, diabetic, depressed and afflicted by other psychological issues, his weight was between 70-75kg and his height was 177cm.

30/9/1999 (day of the accident): Yokokawa was transported to the National Institute of Radiological Sciences (NIRS) via helicopter and was nauseous. He was not transferred to another hospital. 

His main issue was diabetes, as during radiation exposure, the body produces sugar into the blood. Yokokawa was not responding to insulin and had hyperglycemia. His white blood cell count lessened. Yokokawa was placed in a sterile room to prevent infection. 

14/10: Yokokawa's white blood cell count declined. 

16/10: After a recovery, the white blood cell count declined again, as well as his platelet count.

17/10: Platelet transfusion. They dropped again. Yokokawa was moved into a more sterile room. 

20/10: Platelet transfusion.

23/10: Platelet transfusion.

27/10: Yokokawa's white blood cell count recovered to a healthy level.

November: Yokokawa had been emotionally drained, worrying about Ouchi and Shinohara and blaming himself for everything. It had an adverse effect on his treatment however he was still the most stable of the three. A psychologist from Chiba visited him for interviews and advised him to not watch the news as Tokaimura was the story of the year and everyone talked about it. Yokokawa was moved to a more public room.

Due to his smoking, the cells in his lungs died, releasing their fluid, and making breathing difficult. Yokokawa had hypoxia (low oxygen) and dealt with exhaustion and the inability to move. He also lost his hair but it came back eventually. The mucus of his mouth became fragile and sometimes Yokokawa accidentally knocked it out and thus he bled into his mouth, however that was not painful. Another area had a growth defect. That too did not bother him. His condition improved. 

20/12: Yokokawa was discharged. His hair was gradually returning and his white blood cell count was higher than ever. 

21/12: Yokokawa learnt about the death of Ouchi and cried all night.

Future: Yokokawa returned to NIRS in January, April, and November of 2000 as well as June of 2001 for two days each time to undergo treatments to make sure there were still no issues from radiation. Yokokawa would undergo treatments and examinations such as blood cell count, serum chemistry, hormones and tumor markers, analysis of lymphocytes, bone marrow tap, and urinalysis. He visited and ophthalmologist, dentist, cardiologist, and psychiatrist. In January of 2000 and June of 2001, due to diabetes Yokokawa suffered a retinal hemorrhage. His high blood pressure and diabetes became worse and so did his depression. He gained 8kg and had some skin defects.

As of the writing of this post on 31/8/2026, Yokokawa is still alive. I wish him good health.