Hiroshima : 70 Years After the A-bombing

August 8: “Surveyed damage: horrendous”

Inside the small notebook with “Military: Top Secret” printed on the cover is a record of daily activities written with a fountain pen in a neat hand.

The writer, Tetsuzo Kitagawa, was a 37-year-old commander assigned to the Japanese Imperial Navy’s Technical Research Department in Tokyo. Before joining the navy, he　earned undergraduate and graduate degrees in science at Kyoto Imperial University and was doing research into neutrons, which had only recently been discovered.

According to his work log, Mr. Kitagawa received a phone call from the Ministry of the Navy just before noon on August 7 telling him that Hiroshima had been “hit by a special bomb” the day before.

He headed for the Navy Ministry, where he was assigned to a 10-member Navy survey team headed for Hiroshima that had been formed under secret orders from Mitsumasa Yonai, Minister of the Navy. The team took off from Haneda Airport at 4 p.m. in a special aircraft and arrived at the air station in Iwakuni, Yamaguchi Prefecture, at 7:30 p.m.

The Navy survey team entered bombed-out Hiroshima in the early morning on August 8. “Surveyed damage: horrendous,” Mr. Kitagawa wrote matter-of-factly. When his work log is compared against reports and letters he wrote later, the content of the survey becomes clear.

At the site of Hiroshima Castle, whose tower had collapsed, Mr. Kitagawa met up with the Kure Naval Arsenal survey team led by Capt. Matao Mitsui, and they joined forces. They tried to determine where the atomic bomb had exploded by referring to the direction in which buildings, power poles and trees had collapsed. In the afternoon they went to the village of Kameyama (now Kabe-cho, Asa Kita Ward), where cylindrical aluminum devices had been found attached to parachutes. They retrieved two of the wireless devices, and ascertained that they were intended to measure the shock wave generated by the blast.

The group from Tokyo returned there on August 9 after receiving word of a possible invasion by the Soviet Union. But in his entry for August 10 Mr. Kitagawa noted that he stayed behind to attend a meeting of a joint Army-Navy study group at the Hiroshima Army Ordnance Supply Depot.

The study group, which met at the Army Ordnance Supply Depot (now the site of Hiroshima University’s Kasumi Campus) under the auspices of the Imperial General Headquarters, determined that the bomb that had been dropped was an atomic bomb. Among those present were Yoshio Nishina of the Institute of Physical and Chemical Research (Riken), to which the army had delegated the task of researching the development of an atomic bomb, and Bunsaku Arakatsu, a professor at Kyoto University, which had received a similar assignment from the navy. The draft of the report to the Imperial General Headquarters was prepared by Seiichi Niizuma, an army staff officer. (The report was donated to the Hiroshima Peace Memorial Museum in 1994.)

In his diary Mr. Kitagawa wrote, “Went around the city with Mr. Niizuma collecting samples (on our own).” The two men departed for Kyoto on the night of August 10. Mr. Kitagawa returned to Tokyo on August 14 and began working on the report at the offices of the Imperial Japanese Navy Technical Department. The next day, the imperial rescript announcing the end of the war was issued. “Burned classified documents,” he wrote in his log.

But he did not burn his records related to the atomic bombing. His work log notes that he attended a meeting with people from Kyoto University on “F [fission] research” for the development of an atomic bomb on July 21. Mr. Kitagawa kept a report dated August 10 on the “survey of the destruction caused by the Hiroshima air raid” and a telegram sent to him on August 15 by Prof. Arakatsu, who had measured the beta rays emitted by the soil samples that he had brought back from Hiroshima. In the telegram he stated that he had determined that the “new type” of bomb dropped on Hiroshima was an atomic bomb.

After the war, Mr. Kitagawa worked on the development of safety engineering and invented a hydrogen sulfide detector tube. He also served as a professor at Yokohama National University. Mr. Kitagawa’s son Fujio, is president of Komyo Rikagaku Kogyo (headquartered in Kawasaki, Kanagawa Prefecture), which manufactures many gas detector tubes based on his father’s invention.

“He must have felt his involvement in research into the development of an atomic bomb was a black mark on his career,” Mr. Kitagawa said. “He didn’t say much about the survey, and he didn’t get a certificate [Atomic Bomb Survivor’s Certificate] either.” Nevertheless he preserved all of his records in a briefcase.

In 2004, prior to the opening of the Yamato Museum, Fujio donated his father’s records of the survey team’s work to the City of Kure. He kept his father’s work log, which included postwar entries about the family, and the letters his father had written to his mother. By that time, only copies of the originals remained.

Mr. Kitagawa had sent his wife Miwako, 34, back to her family home in Shiga Prefecture, where he believed she would be safer. In a letter he sent to her four days after the end of the war, he wrote emotionally of the terrible conditions in Hiroshima, saying, “The removal of the dead bodies hasn't been finished yet, so it is truly pitiable.” With regard to the new start that both he and Japan would make, he said, “The basics of science must permeate every aspect of daily life as part of the nation's culture.”

(Originally published on May 12, 2014)