Late Japanese physicist stirred international opinion against nuclear weapons by presenting data on radiation exposure

by Kyosuke Mizukawa, Staff Writer

Yasushi Nishiwaki was a Japanese physicist who helped lay the foundation for the establishment of the Pugwash Conferences, an international organization of scientists who seek the abolition of nuclear arms. The Pugwash Conferences was awarded the Nobel Peace Prize in 1995 for its efforts to eliminate nuclear weapons. Buoyed by the national ban-the-bomb movement that swept Japan following the exposure of Japanese nationals to radioactive fallout from a hydrogen bomb test at Bikini Atoll, Dr. Nishiwaki took a stand against nuclear weapons and made scientific presentations in Europe on the damage caused by radiation. Newly-released materials are now casting further light on his achievements.

On March 1, 1954, the United States conducted a hydrogen bomb test, code named “Castle Bravo,” at Bikini Atoll in the Marshall Islands, located in the central Pacific Ocean. The crew members of a Japanese fishing boat, called the Daigo Fukuryu Maru (The Lucky Dragon No. 5), were exposed to radioactive fallout from the nuclear blast. Reading about the incident in a newspaper on March 16, Dr. Nishiwaki took a night train from Osaka to Yaizu, Shizuoka Prefecture. The following day, he began collecting substances from the boat and the crew members and measuring their radiation levels.

In July 1954, Dr. Nishiwaki started a tour of Europe, explaining the effects of radiation by showing his own and other Japanese scientists’ research data. A Norwegian newspaper for August 17, 1954 carried the article “Japanese scientist calls for suspension of nuclear tests in Pacific.” Newspapers in European nations wrote about the profound effects of the bomb, covering the health damage suffered by the crew of the fishing boat. Based on the report by Dr. Nishiwaki, Joseph Rotblat, a British physicist, realized that the hydrogen bomb used in the test was a “dirty bomb.” It is believed that Bertrand Russell, a British philosopher, had thought that radioactive contamination was not as serious as petroleum pollution until Dr. Rotblat told him about the grim consequences of radiation exposure. Mr. Russell was later a leading figure in the antinuclear movement.

Dr. Nishiwaki was born in Osaka and studied physics at Osaka Imperial University (today’s Osaka University). During World War II, he was involved in the “Ni-Go Project,” the Japanese Army’s effort to develop nuclear weapons. After the war, he studied radiation biophysics in the United States.

“His prompt action, in reporting the damage suffered by the Daigo Fukuryu Maru to the world, can be traced back to his mother,” said Masakatsu Yamazaki, an expert on the history of science and a professor emeritus at the Tokyo Institute of Technology. Dr. Yamazaki has been organizing materials connected to the work of the late Dr. Nishiwaki at the request of family members. Dr. Nishiwaki’s mother, Rika, began lending her support to female victims of the Hiroshima atomic bombing in 1953. Based in Osaka, she worked with Hiroshima citizens and took the lead in fundraising campaigns to cover the costs of treatment for the victim’s burn scars. To enable Dr. Nishiwaki to travel to Europe, members of signature drive groups in Osaka and businesses donated some two million yen.

Invited by Dr. Linus Pauling, an American scientist who called for a ban on nuclear tests, Dr. Nishiwaki visited the United States in 1959. He gave about 40 lectures on the damage caused by radiation from the atomic bombs. After serving as a professor at the Tokyo Institute of Technology, he moved to the International Atomic Energy Agency (IAEA) in Austria in 1968. After retiring from the IAEA, he taught at the University of Vienna, where he studied the risk of accidents at nuclear power plants. He spent his last years in the city of Osaka. According to members of his family, he looked distressed when an accident occurred, despite his repeated warnings, at the Fukushima No. 1 (Daiichi) nuclear power plant in March 2011. In the same month, he passed away at the age of 94.

Dr. Yamazaki will attend this year’s Pugwash International Conference, taking place in Nagasaki between November 1 and 5. He said, “I would like people to see, through Dr. Nishiwaki’s research, that this conference is based on the strong desire of Japanese scientists and citizens who have seen Hiroshima, Nagasaki, and Bikini.”

Major events connected to Dr. Yasushi Nishiwaki and the Pugwash Conferences

March 1, 1954: The United States conducts the “Castle Bravo” hydrogen bomb test at Bikini Atoll in the Marshall Islands in the central Pacific Ocean.

March 14: Twenty-three crew members of the Daigo Fukuryu Maru (The Lucky Dragon No. 5) return to port in Yaizu, Shizuoka Prefecture, after being exposed to radioactive fallout from the bomb test.

March 16: The Daigo Fukuryu Maru’s exposure to radioactive fallout is reported in the newspaper.

March 17: Yasushi Nishiwaki measures the radiation levels of the Daigo Fukuryu Maru at Yaizu Port. He writes a letter to the chairman of the U.S. Atomic Energy Commission and reports on the disaster.

March 18: Scientists from the University of Tokyo laboratory, headed by Dr. Kenjiro Kimura, begin analyzing the “ashes of death.” They identify about 30 different radioactive nuclides including uranium 237 by May.

May 1954: The Osaka Regional Liaison Office against the H-bomb is established. The group organizes lectures by Dr. Nishiwaki and holds signature drives calling for a ban on nuclear and hydrogen bombs.

July: Dr. Nishiwaki visits Europe and reports on the facts found by Japanese scientists about the radioactive fallout from the hydrogen bomb test, speaking at more than 20 places in 10 countries before returning to Japan in November.

August: Dr. Nishiwaki meets physicist Joseph Rotblat at a university in Belgium. Dr. Nishiwaki hands Dr. Rotblat a memo which contains research data on radioactive substances.

October: From Dr. Nishiwaki’s data on uranium 237 and others, Dr. Rotblat determines that the hydrogen bomb used in the “Castle Bravo” test is a “dirty bomb,” which produces an enormous amount of radioactive fallout.

December: Dr. Rotblat tells Bertrand Russell, a British philosopher, that the Castle Bravo bomb is a “dirty bomb.” Mr. Russell makes a statement through the British Broadcasting Corporation, warning of the great danger of hydrogen bombs to human life.

July 1955: Bertrand Russell, Albert Einstein, and nine other prominent people issue the Russell-Einstein Manifesto, a statement that calls for the elimination of nuclear weapons.

July 1957: Following the spirit of the manifesto, the first meeting of the Pugwash Conference is held in Canada. Dr. Hideki Yukawa and two other Japanese attend the conference.

(Originally published on October 29, 2015)