Paul Kazuo Kuroda (1917–2001)

Paul Kazuo Kuroda, professor of chemistry at the University of Arkansas (UA) in Fayetteville (Washington County), brought international attention to scientific research in Arkansas by correctly predicting the presence of naturally occurring nuclear reactors nearly twenty years before the first discovery of a reactor of this kind in the Oklo Mines in the Republic of Gabon in west-central Africa.

Paul Kuroda was born on April 1, 1917, in Kurogi, Fukoka Prefecture, Kyushu, Japan, the only child of Kanjiro Kuroda—a school teacher, official at the Ministry of Education, and noted calligrapher—and Shige Kuroda. Kuroda earned BS and doctoral degrees in pure chemistry from Tokyo Imperial University (now the University of Tokyo) in 1939 and 1944, respectively. Upon completion of his doctorate, he earned an assistant professorship of chemistry at Tokyo Imperial University. He taught there until accepting a fellowship at the University of Minnesota in 1949. Kuroda became an assistant professor at the University of Arkansas in 1952 and was promoted to associate professor in 1955, the year he became an American citizen.

His initial scientific research proposal was “Trace Elements in Meteorites and the Age of the Solar System.” It was presented in 1954 but not published until 1956. Even then, it was largely not accepted, but it remained at the forefront of scientific topics because of its novelty.

After a brief time as an associate chemist at the Argonne National Laboratory in 1957, Kuroda returned to the University of Arkansas, where he taught, advised students, and conducted his research from 1960 until his retirement in 1987.

Kuroda married Loes Moren from The Hague, Netherlands, who held an MS in pharmacy from the University of Leiden. The Kurodas had three children.

Kuroda was the first researcher to calculate mathematically that Enrico Fermi’s reactor had the potential to operate in nature. He made the prediction of the existence of self-sustaining, naturally occurring nuclear reactors early in his career and continually researched this, despite negative speculation in the field of chemistry. He called it his life’s work. However, Kuroda later recalled, “Scientists were saying that if this idiot is an indication of the program at the University of Arkansas, there must be nothing there at all.”

Kuroda actively took to pinpointing locations of possible natural nuclear reactors, one of which he suspected was in Wisconsin. Nearly twenty years later, in 1972, the Atomic Energy Commission of France discovered ore with a lower than usual percentage of the Uranium-235 isotope. This discovery signaled to researchers that a naturally occurring reactor had existed at that location in the distant past, and Kuroda received widespread attention. When the Atomic Energy Commission of France traced ore to the Oklo Mines in the Republic of Gabon in west-central Africa, where the discovery of a naturally occurring nuclear reactor was made, Kuroda was further validated as a credible, leading researcher of chemistry. “These reactions could’ve been one of the most important factors in creating mountains and continents thousands of feet below the surface, possibly perpetually for about 1 million years,” Kuroda said.

“Paul Kuroda pops up spectacularly in the news with increasing frequency,” wrote the Intercom.“He has created a stir in nuclear circles more than once for his unorthodox research methods,” which included a method used to determine the age of the universe in a comparatively reversed process.

Kuroda was an active member of the American Chemical Society and chairman of the organization in 1960. Further involvement included membership in the American Association Advancement of Science, the American Geophysical Society, and the Sigma Xi Society, of which he served as chairman. Kuroda received the most highly esteemed science award in Japan, the award for pure chemistry, from the Japanese Chemical Society. He also received multiple awards from the American Chemical Society.

In 1963, Kuroda and one of his former graduate students from the University of Arkansas were among the sixteen American scientists to speak at the International Atomic Energy Agency Symposium on Radioactive Dating in Athens, Greece. There, he presented “Dating Methods Based on the Process of Nuclear Fission.” His research on various topics of chemistry was regularly funded by the Atomic Energy Commission, the U.S. Department of Energy, and the National Science Foundation. In 1979, he became the first Edgar Wertheim Distinguished Professor of Chemistry, and while at UA he authored or co-authored nearly 400 publications.

Kuroda retired from the University of Arkansas in 1987. He died on April 16, 2001, at his home in Las Vegas, Nevada.

After his death, it was reported that, before Kuroda left Japan following World War II, he was secretly given documents showing the Japanese army’s plans for building an atomic bomb (a relatively weak one). Kuroda had worked on the project as a research assistant. The documents were supposed to be destroyed, but he instead brought them to the United States and kept them for more than fifty years. After his death, his widow returned the documents to a research institute in Japan so they could aid in the study of Japan’s wartime history.

For additional information:
“Atomic Plans Returned to Japan.” BBC News, August 3, 2002. Online at http://news.bbc.co.uk/2/hi/asia-pacific/2170881.stm (accessed January 31, 2022).

Clark, James H. “The Last Laugh Is on Them.” Arkansas Alumnus (June 1973): 14–15.

Nichols, Bob. “Outstanding Faculty Awards.” Arkansas Alumnus (June 1963): 14–15.

“Paul K. Kuroda (1917–2001).” Meteoritics & Planetary Science 36 (2001): 1409–1410.

April M. Robertson
University of Arkansas, Fayetteville