History Lessons I: Walter Grunden on Japan’s Nuclear Past

As we commemorate another anniversary of the nuclear attacks on Hiroshima and Nagasaki, VJ day and the Japanese surrender, yet another round of speculation has emerged about Japan’s wartime nuclear activities. This time, the charge is led by Bill Streifer, an internet “researcher and author” in a piece entitled Hungnam, North Korea: Delving into North Korea's Long Nuclear Past on DC Bureau, a website covering national security news.

For decades it has been well known that Japan conducted research toward the military application of nuclear energy during World War II. But some have attempted to push the story further, alleging that the Japanese also conducted extensive nuclear research in Korea and perhaps even succeeded in testing a nuclear weapon near the city of Hungnam in the closing days of the war.   This event, they argue, was since covered up by a “conspiracy of silence” perpetrated by the Japanese government, ostensibly in order to protect the image of Japan as victims of a nuclear attack when they, too, had all along secretly engaged in a nuclear arms “race”.

The primary advocate of this conspiratorial narrative has been Robert K. Wilcox, a free-lance journalist and screenwriter, who presented his case in Japan’s Secret War, first published in 1985. Since then, numerous others have cited the Wilcox book as a credible source and repeated the unsubstantiated claim of a nuclear test near Hungnam. The History Channel even got into the act with a documentary entitled “Japan’s Atomic Bomb.”   Such works have also raised the question about whether the Soviets and North Koreans benefited in any way from Japan’s wartime research.

The problem is that much of this work has not been done by historians but rather by motivated amateurs. To check the historical record, we contacted Walter Grunden at Bowling Green State University, who has done first-rate research on the issue including: “Hungnam and the Japanese Atomic Bomb: Recent Historiography of a Postwar Myth” and “Wartime Nuclear Weapons Research in Germany and Japan”. In addition, Prof. Grunden is the author of Secret Weapons & World War II .  Here we reproduce in two parts some of the core findings from Grunden’s review of this recent work; the entire essay—with extensive references to underlying sources--can be found on Prof. Grunden’s website. The bottom line: theories about a Japanese program, an actual test, and links to the Soviet and North Korean nuclear programs are simply false.

Walter Grunden

Historians have long known that both the Imperial Japanese Army and the Imperial Japanese Navy established programs for the military exploitation of nuclear fission during the war, the army’s “Ni-gō,” program and the navy’s “F-gō” program, both officially operational from May 1943. The two were ultimately merged toward the very end of the war. Allied bombing of Tokyo all but brought the army’s effort to an end. The navy program went forward but ultimately did not succeed.

The Korean connection came in part through the Japanese search for uranium. The Japan Nitrogenous Fertilizer Company (Nippon Chisso Hiryō, or Nitchitsu) set up operations in Korea during the 1920s and diversified into one of the major Japanese conglomerates operating there; another firm established by the firm’s founder Jun Noguchi, Chōsen Hydroelectric (Chōsen Suiden), developed over 1,000 megawatts of hydro power-generating capacity, powering both his own needs and others in the Northern half of the peninsula. Among the facilities developed by Noguchi were plants providing war-related materials in the Hungman area, including the production of ammonium, magnesium metal, explosives, nitrogen-enriched fertilizers and high-octane aviation fuel for the navy.

In the manufacture of these highly volatile chemicals, the electrolytic process yielded small amounts of “heavy water” (i.e. deuterium oxide) as a by-product. Long after the war, conspiracy theorists seized on the presence of heavy water at the so-called NZ plant as evidence of Japan’s “nuclear research” at Hungnam; Wilcox’s Japan’s Secret War cited above is exemplary of the genre. (1)   Heavy water can serve as a reactor moderator--a medium used to decrease the speed of fast neutrons sufficiently to cause more effective fission of uranium atoms—but is not the only material that can be used for the purpose; the US was working with graphite technology to the same ends. Yet the opportunity for a leap of faith is clear if you are looking for evidence of your priors. The Germans used heavy water in the construction of their nuclear reactors, they were producing heavy water in abundance at Vemork, and their electrolysis equipment there was powered by a huge hydroelectric generating plant. The Japanese must have been doing the same thing. QED.

But the dots do not connect so easily. First, there is no proof that the NZ factory was ever committed to producing heavy water on an industrial scale or specifically for nuclear research in Japan or Korea. Secondly, there is no evidence that Japanese scientists actually attempted to build a reactor. What is well documented in Japanese and U.S. sources is that both the Japanese army and navy made efforts to locate uranium-bearing ores in Korea. But again, making the effort does not mean that they were successful and there is in fact ample evidence that they weren't. Sometime late in the war, the navy allegedly acquired about 200 pounds of uranium oxide through the black market in Shanghai, but even if it had been of high grade, this amount still would not have been enough to produce an atomic bomb. (2)

Stephan Haggard

Despite the fact that there is little evidence with respect to these earlier efforts, allegations persist that Japan’s nuclear research efforts were moved to Korea in the last weeks or months of the war and that the Soviet Army might have benefited from them; Prof. Grunden takes up this issue in the next post.