Scientist immediately sought details from U.S. on 1954 Bikini H-bomb test


An exhibit at a U.S. nuclear testing museum tells the little-known story of a Japanese scientist in the 1950s who asked the United States in writing for information about how to help Japanese fishermen exposed to high-level radiation in a hydrogen bomb test at Bikini Atoll soon after the incident.

On March 17, 1954, biophysicist Yasushi Nishiwaki wrote a letter to the chief of what was then the U.S. Atomic Energy Commission. It was the day after the crew of the tuna boat Fukuryu Maru No. 5 was found to have been exposed to fallout from the March 1 nuclear test.

In the letter displayed at the Atomic Testing Museum in Nevada, Nishiwaki, an assistant professor at Osaka City University at the time, asked the commission for information on types of elements contained in the fallout and methods for decontamination. Nishiwaki, who became a professor emeritus at the University of Vienna, died last year at age 94.

“In order to minimize possible radiation injury and damage to human subjects in Japan, we need to know immediately in detail the possible types of radioactive elements contained in the radioactive contaminated material,” he wrote.

“If possible, please inform us as promptly and completely as possible and advise the best way to eliminate radioactive contamination and minimize radioactive injury in this case.”

The boat’s 23 crew members suffered nuclear fallout from the hydrogen bomb test while they were operating near the atoll. The boat returned to Yaizu, Shizuoka Prefecture, on March 14, 1954. Two days later the Yomiuri Shimbun reported the crew’s exposure to radioactive substances.

Nishiwaki took a night train from Osaka and reached Yaizu on the morning of March 17. He examined the radioactive substances that had adhered to the boat, crew and catch.

The study prompted Nishiwaki to quickly compose his letter. Written in English, the letter says that the Japanese boat “suffered a considerable amount of radioactive contamination and all the crew were identified to have suffered from radiation injuries.”

Nishiwaki said later he sent a number of letters to the U.S. seeking information on elements contained in the bomb but that his letters were ignored. Many Japanese scientists made similar complaints about a lack of information from the U.S. on the matter.

Masakatsu Yamazaki, a science historian at Tokyo Institute of Technology, said the letter shows Nishiwaki was without doubt the first to inform the U.S. of the human damage suffered as a result of the Bikini test.

Nishiwaki wrote the letter even before he confirmed that such elements as strontium and iodine were contained in the hydrogen bomb fallout, Yamazaki said.

Later in 1954, Nishiwaki visited Europe and handed the results of his research on health damage from radioactive materials suffered by the fishermen to British physicist Joseph Rotblat.

The following year Rotblat said the U.S. used a so-called dirty bomb in the Bikini test that scattered a massive amount of radioactive materials.